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Emergency and Acute Medicine – Barotrauma
Overview and Definitions
Barotrauma refers to tissue injury caused by expansion or contraction of gas within enclosed body spaces when ambient pressure changes. This process follows Boyle’s law, where pressure and volume are inversely related at constant temperature. As external pressure increases or decreases, gas volume correspondingly decreases or increases. Solid and liquid-filled spaces equalize pressure uniformly, whereas gas-filled cavities are vulnerable, with the greatest volume changes occurring near the surface.
Etiology And Pathophysiology
Tissue injury occurs when pressure in a gas-filled space fails to equalize with the surrounding environment. External air pockets in dive masks or suits may expand or contract. Paranasal sinus injury typically occurs during descent due to impaired pressure equalization through the nasal ostia, most commonly affecting the frontal sinus. External ear barotrauma results from blockage of the auditory canal, creating a vacuum. Middle ear barotrauma is the most frequent form, seen in approximately 30% of inexperienced and 10% of experienced divers, caused by inadequate eustachian tube function leading to increasing negative pressure across the tympanic membrane. Inner ear barotrauma occurs with rapid pressure changes during maneuvers such as Valsalva or Frenzel, potentially causing round or oval window rupture. Dental barotrauma results from trapped gas within or around teeth. Gastrointestinal barotrauma occurs during ascent as swallowed air expands. Pulmonary barotrauma arises during ascent when gas trapped in the lungs expands, leading to alveolar rupture, pneumomediastinum, pneumothorax, or arterial gas embolism. Patients with asthma or COPD are at higher risk due to altered lung compliance.
Clinical Features
Facial findings may include conjunctival hemorrhage, facial edema, and swelling from an occlusive dive mask. Extremities can develop localized edema and erythema from tight dive suits. Sinus involvement presents with congestion, pain, epistaxis, maxillary tooth pain, or cheek and lip numbness from trigeminal nerve involvement. External ear injury may progress from canal edema to hemorrhage and tearing. Middle ear barotrauma begins with a clogged sensation and increasing pain, potentially progressing to tympanic membrane rupture, with findings described by the Teed classification. Inner ear injury causes tinnitus, hearing loss, and vertigo, typically less severe than decompression illness. Dental barotrauma presents as severe tooth pain. Gastrointestinal involvement causes belching, flatulence, and abdominal distention. Pulmonary barotrauma manifests as chest pain, cough, hemoptysis, subcutaneous emphysema, pneumomediastinum, pneumothorax, dyspnea, and delayed neck fullness, dysphagia, or voice changes.
History And Examination
A detailed dive history is essential, focusing on timing of symptoms relative to ascent, descent, or delay after the dive. Physical examination should include careful inspection of the tympanic membranes, evaluation for subcutaneous emphysema of the neck or chest, lung examination for pneumothorax, and a focused neurologic assessment for imbalance or ataxia suggesting inner ear involvement.
Essential Evaluation
Diagnosis is primarily clinical and based on history and meticulous physical examination. Additional testing is guided by suspected complications.
Diagnostic Studies
Arterial blood gas analysis is indicated for pulmonary symptoms. Imaging may include sinus CT or plain radiographs, chest radiography for pulmonary barotrauma, and upright or decubitus abdominal films if free air is suspected from visceral rupture.
Differential Diagnosis
Consider decompression sickness, otitis media, otitis externa, and sinusitis.
Prehospital Care
In barotrauma related to descent, symptoms generally do not worsen once normal atmospheric pressure is restored unless rupture has occurred. If air evacuation is required, cabin pressure should be maintained at sea level or flight altitude kept below 1,000 feet to prevent symptom exacerbation.
Initial Stabilization And Emergency Management
Management follows standard airway, breathing, and circulation principles. Ill-appearing patients should receive 100% oxygen. Intubation may be required for significant cervical subcutaneous emphysema. Immediate needle thoracostomy is indicated for suspected tension pneumothorax.
Emergency Department Treatment
Intravenous access is established in unstable patients. Active bleeding from the ear or nose should be controlled. Tube thoracostomy is required for large pneumothoraces. Nasal or systemic decongestants are used for middle ear or sinus congestion. Antibiotics are indicated when tympanic membrane or sinus rupture is present, along with appropriate analgesia.
Medications
Amoxicillin may be used orally, with trimethoprim–sulfamethoxazole as an alternative. Oxymetazoline nasal spray may be given for short-term decongestion, and pseudoephedrine can be used systemically when appropriate.
Disposition And Follow-Up
Admission is required for pulmonary barotrauma and for inner ear barotrauma associated with round window rupture or severe vertigo. Most other cases may be discharged with close follow-up. Otolaryngology referral is recommended for tympanic membrane rupture or inner ear involvement.
Critical Clinical Insights And Common Errors
Patients presenting with barotrauma should be closely monitored for evolving decompression sickness. A thorough lung examination is essential to identify pneumothorax early. In cases of pulmonary barotrauma, any history of neurologic symptoms should raise concern for arterial gas embolism and prompt urgent evaluation.
Overview and Definitions
Barotrauma refers to tissue injury caused by expansion or contraction of gas within enclosed body spaces when ambient pressure changes. This process follows Boyle’s law, where pressure and volume are inversely related at constant temperature. As external pressure increases or decreases, gas volume correspondingly decreases or increases. Solid and liquid-filled spaces equalize pressure uniformly, whereas gas-filled cavities are vulnerable, with the greatest volume changes occurring near the surface.
Etiology And Pathophysiology
Tissue injury occurs when pressure in a gas-filled space fails to equalize with the surrounding environment. External air pockets in dive masks or suits may expand or contract. Paranasal sinus injury typically occurs during descent due to impaired pressure equalization through the nasal ostia, most commonly affecting the frontal sinus. External ear barotrauma results from blockage of the auditory canal, creating a vacuum. Middle ear barotrauma is the most frequent form, seen in approximately 30% of inexperienced and 10% of experienced divers, caused by inadequate eustachian tube function leading to increasing negative pressure across the tympanic membrane. Inner ear barotrauma occurs with rapid pressure changes during maneuvers such as Valsalva or Frenzel, potentially causing round or oval window rupture. Dental barotrauma results from trapped gas within or around teeth. Gastrointestinal barotrauma occurs during ascent as swallowed air expands. Pulmonary barotrauma arises during ascent when gas trapped in the lungs expands, leading to alveolar rupture, pneumomediastinum, pneumothorax, or arterial gas embolism. Patients with asthma or COPD are at higher risk due to altered lung compliance.
Clinical Features
Facial findings may include conjunctival hemorrhage, facial edema, and swelling from an occlusive dive mask. Extremities can develop localized edema and erythema from tight dive suits. Sinus involvement presents with congestion, pain, epistaxis, maxillary tooth pain, or cheek and lip numbness from trigeminal nerve involvement. External ear injury may progress from canal edema to hemorrhage and tearing. Middle ear barotrauma begins with a clogged sensation and increasing pain, potentially progressing to tympanic membrane rupture, with findings described by the Teed classification. Inner ear injury causes tinnitus, hearing loss, and vertigo, typically less severe than decompression illness. Dental barotrauma presents as severe tooth pain. Gastrointestinal involvement causes belching, flatulence, and abdominal distention. Pulmonary barotrauma manifests as chest pain, cough, hemoptysis, subcutaneous emphysema, pneumomediastinum, pneumothorax, dyspnea, and delayed neck fullness, dysphagia, or voice changes.
History And Examination
A detailed dive history is essential, focusing on timing of symptoms relative to ascent, descent, or delay after the dive. Physical examination should include careful inspection of the tympanic membranes, evaluation for subcutaneous emphysema of the neck or chest, lung examination for pneumothorax, and a focused neurologic assessment for imbalance or ataxia suggesting inner ear involvement.
Essential Evaluation
Diagnosis is primarily clinical and based on history and meticulous physical examination. Additional testing is guided by suspected complications.
Diagnostic Studies
Arterial blood gas analysis is indicated for pulmonary symptoms. Imaging may include sinus CT or plain radiographs, chest radiography for pulmonary barotrauma, and upright or decubitus abdominal films if free air is suspected from visceral rupture.
Differential Diagnosis
Consider decompression sickness, otitis media, otitis externa, and sinusitis.
Prehospital Care
In barotrauma related to descent, symptoms generally do not worsen once normal atmospheric pressure is restored unless rupture has occurred. If air evacuation is required, cabin pressure should be maintained at sea level or flight altitude kept below 1,000 feet to prevent symptom exacerbation.
Initial Stabilization And Emergency Management
Management follows standard airway, breathing, and circulation principles. Ill-appearing patients should receive 100% oxygen. Intubation may be required for significant cervical subcutaneous emphysema. Immediate needle thoracostomy is indicated for suspected tension pneumothorax.
Emergency Department Treatment
Intravenous access is established in unstable patients. Active bleeding from the ear or nose should be controlled. Tube thoracostomy is required for large pneumothoraces. Nasal or systemic decongestants are used for middle ear or sinus congestion. Antibiotics are indicated when tympanic membrane or sinus rupture is present, along with appropriate analgesia.
Medications
Amoxicillin may be used orally, with trimethoprim–sulfamethoxazole as an alternative. Oxymetazoline nasal spray may be given for short-term decongestion, and pseudoephedrine can be used systemically when appropriate.
Disposition And Follow-Up
Admission is required for pulmonary barotrauma and for inner ear barotrauma associated with round window rupture or severe vertigo. Most other cases may be discharged with close follow-up. Otolaryngology referral is recommended for tympanic membrane rupture or inner ear involvement.
Critical Clinical Insights And Common Errors
Patients presenting with barotrauma should be closely monitored for evolving decompression sickness. A thorough lung examination is essential to identify pneumothorax early. In cases of pulmonary barotrauma, any history of neurologic symptoms should raise concern for arterial gas embolism and prompt urgent evaluation.
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Emergency and Acute Medicine – Barbiturates Poisoning
Overview and Definitions
Barbiturates are sedative–hypnotic agents derived from barbituric acid that exert their effects by enhancing γ-aminobutyric acid (GABA) activity at the GABA-A receptor. At toxic concentrations, they directly open chloride channels, leading to profound CNS depression. Additional effects include inhibition of vascular smooth muscle tone and direct myocardial depression, which contribute to hypotension and shock. Poisoning may be intentional or accidental.
Etiology
Toxicity results from overdose of barbiturates, either intentional (suicide attempt) or unintentional due to medication error, drug interactions, or dose escalation.
Clinical Features
Central nervous system findings range from lethargy, slurred speech, incoordination, ataxia, and loss of reflexes to deep coma that can closely resemble brain death. Cardiovascular manifestations include hypotension and bradycardia. Respiratory depression and hypothermia are common. Ophthalmologic findings may include miosis, nystagmus, and dysconjugate gaze. Characteristic bullae, known as “barb blisters,” may develop, particularly after prolonged immobilization.
History and Examination
Assessment should focus on determining intent, including evidence of pill bottles, history of depression or suicidal ideation, and recent medication changes. Estimating the duration of unresponsiveness is important. Examination typically reveals CNS depression ranging from ataxia to coma, respiratory compromise, hypotension, bradycardia, hypothermia, abnormal eye movements, and skin bullae.
Essential Evaluation
Immediate assessment includes fingerstick glucose, continuous oxygen saturation monitoring, and blood pressure measurement. A critical caution is that barbiturate poisoning can mimic brain death; this diagnosis must not be made until drug effects are excluded.
Diagnostic Testing
Laboratory studies include electrolytes, BUN, creatinine, glucose, and anion gap assessment, along with urinalysis for myoglobin and crystalluria, creatine phosphokinase for rhabdomyolysis, and urine toxicology screening. Serum phenobarbital levels should be obtained when suspected, with acetaminophen and salicylate levels assessed in possible suicide attempts. Imaging may include noncontrast head CT for altered mental status and chest radiography if aspiration is suspected. Lumbar puncture is reserved for selected cases where CNS infection is a concern.
Differential Diagnosis
Consider other sedative–hypnotic intoxications including GHB, carbon monoxide poisoning, CNS infections, intracranial mass lesions, hypoglycemia, uremia, electrolyte disturbances such as hypermagnesemia, postictal states, hypothyroidism, hepatic failure, and primary psychiatric conditions.
Prehospital Care
Moderate to severe poisonings require paramedic transport. Airway protection with intubation is often necessary due to respiratory depression or loss of protective reflexes. Supplemental oxygen, IV access, and fluid boluses for hypotension should be initiated promptly.
Initial Stabilization and Emergency Management
Management priorities follow ABC principles. Severe toxicity frequently necessitates endotracheal intubation and mechanical ventilation. Hypotension should be treated with aggressive isotonic fluid resuscitation, typically 1–2 liters of normal saline, with vasopressors added if shock persists. Activated charcoal effectively binds barbiturates and reduces absorption.
Therapeutic Interventions
A single dose of activated charcoal is most effective if administered within one hour of ingestion, provided the airway is protected. Repeated-dose activated charcoal may be used as “gut dialysis” every 2–4 hours if bowel sounds are present. Hypothermia should be corrected with active rewarming. Refractory hypotension requires vasopressor support. Hyperkalemia from rhabdomyolysis should be treated with standard therapies. Phenobarbital levels should be rechecked within 2–4 hours to assess trends. Hemodialysis is indicated in cases of renal failure, prolonged coma, phenobarbital levels above 100 mg/dL, or refractory hypotension. Urinary alkalinization has no role.
Medications
Activated charcoal is given at 1 g/kg orally. Dopamine may be initiated at 5–10 μg/kg/min and titrated as needed, with norepinephrine as an alternative at 2–4 μg/min. Epinephrine may be used as second-line vasopressor therapy.
Disposition and Follow-Up
ICU admission is required for patients with coma, respiratory depression, hypotension, hypothermia, or rhabdomyolysis. Discharge may be considered after at least six hours of observation in asymptomatic patients with two consecutive subtoxic phenobarbital levels. Intentional overdoses mandate psychiatric evaluation, while unintentional cases require medication review and adjustment.
Key Clinical Insights and Common Errors
Profound hypothermia is common and requires accurate core temperature measurement. Rhabdomyolysis should be actively sought, especially in patients with prolonged immobilization. Barbiturate toxicity can cause extended coma, and clinicians must ensure complete drug clearance before considering a diagnosis of brain death.
Overview and Definitions
Barbiturates are sedative–hypnotic agents derived from barbituric acid that exert their effects by enhancing γ-aminobutyric acid (GABA) activity at the GABA-A receptor. At toxic concentrations, they directly open chloride channels, leading to profound CNS depression. Additional effects include inhibition of vascular smooth muscle tone and direct myocardial depression, which contribute to hypotension and shock. Poisoning may be intentional or accidental.
Etiology
Toxicity results from overdose of barbiturates, either intentional (suicide attempt) or unintentional due to medication error, drug interactions, or dose escalation.
Clinical Features
Central nervous system findings range from lethargy, slurred speech, incoordination, ataxia, and loss of reflexes to deep coma that can closely resemble brain death. Cardiovascular manifestations include hypotension and bradycardia. Respiratory depression and hypothermia are common. Ophthalmologic findings may include miosis, nystagmus, and dysconjugate gaze. Characteristic bullae, known as “barb blisters,” may develop, particularly after prolonged immobilization.
History and Examination
Assessment should focus on determining intent, including evidence of pill bottles, history of depression or suicidal ideation, and recent medication changes. Estimating the duration of unresponsiveness is important. Examination typically reveals CNS depression ranging from ataxia to coma, respiratory compromise, hypotension, bradycardia, hypothermia, abnormal eye movements, and skin bullae.
Essential Evaluation
Immediate assessment includes fingerstick glucose, continuous oxygen saturation monitoring, and blood pressure measurement. A critical caution is that barbiturate poisoning can mimic brain death; this diagnosis must not be made until drug effects are excluded.
Diagnostic Testing
Laboratory studies include electrolytes, BUN, creatinine, glucose, and anion gap assessment, along with urinalysis for myoglobin and crystalluria, creatine phosphokinase for rhabdomyolysis, and urine toxicology screening. Serum phenobarbital levels should be obtained when suspected, with acetaminophen and salicylate levels assessed in possible suicide attempts. Imaging may include noncontrast head CT for altered mental status and chest radiography if aspiration is suspected. Lumbar puncture is reserved for selected cases where CNS infection is a concern.
Differential Diagnosis
Consider other sedative–hypnotic intoxications including GHB, carbon monoxide poisoning, CNS infections, intracranial mass lesions, hypoglycemia, uremia, electrolyte disturbances such as hypermagnesemia, postictal states, hypothyroidism, hepatic failure, and primary psychiatric conditions.
Prehospital Care
Moderate to severe poisonings require paramedic transport. Airway protection with intubation is often necessary due to respiratory depression or loss of protective reflexes. Supplemental oxygen, IV access, and fluid boluses for hypotension should be initiated promptly.
Initial Stabilization and Emergency Management
Management priorities follow ABC principles. Severe toxicity frequently necessitates endotracheal intubation and mechanical ventilation. Hypotension should be treated with aggressive isotonic fluid resuscitation, typically 1–2 liters of normal saline, with vasopressors added if shock persists. Activated charcoal effectively binds barbiturates and reduces absorption.
Therapeutic Interventions
A single dose of activated charcoal is most effective if administered within one hour of ingestion, provided the airway is protected. Repeated-dose activated charcoal may be used as “gut dialysis” every 2–4 hours if bowel sounds are present. Hypothermia should be corrected with active rewarming. Refractory hypotension requires vasopressor support. Hyperkalemia from rhabdomyolysis should be treated with standard therapies. Phenobarbital levels should be rechecked within 2–4 hours to assess trends. Hemodialysis is indicated in cases of renal failure, prolonged coma, phenobarbital levels above 100 mg/dL, or refractory hypotension. Urinary alkalinization has no role.
Medications
Activated charcoal is given at 1 g/kg orally. Dopamine may be initiated at 5–10 μg/kg/min and titrated as needed, with norepinephrine as an alternative at 2–4 μg/min. Epinephrine may be used as second-line vasopressor therapy.
Disposition and Follow-Up
ICU admission is required for patients with coma, respiratory depression, hypotension, hypothermia, or rhabdomyolysis. Discharge may be considered after at least six hours of observation in asymptomatic patients with two consecutive subtoxic phenobarbital levels. Intentional overdoses mandate psychiatric evaluation, while unintentional cases require medication review and adjustment.
Key Clinical Insights and Common Errors
Profound hypothermia is common and requires accurate core temperature measurement. Rhabdomyolysis should be actively sought, especially in patients with prolonged immobilization. Barbiturate toxicity can cause extended coma, and clinicians must ensure complete drug clearance before considering a diagnosis of brain death.
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Emergency and Acute Medicine – Atrioventricular Blocks
Overview
Atrioventricular (AV) blocks represent impaired electrical conduction between the atria and ventricles at the level of the AV node or the His–Purkinje system. They are classified by severity and physiologic impact. First-degree AV block involves delayed AV nodal conduction without loss of ventricular beats and is generally benign, occurring in about 1.6% of healthy adults. Second-degree AV block is defined by intermittent failure of atrial impulses to conduct to the ventricles. Mobitz type I (Wenckebach) typically reflects AV nodal disease with progressive PR interval prolongation until a dropped QRS complex and is usually benign, though it may accompany inferior wall myocardial infarction. Mobitz type II reflects infranodal disease with fixed PR intervals and sudden dropped beats, carries a high risk of progression to complete heart block, and has a worse prognosis, particularly with acute myocardial infarction. Third-degree AV block, or complete heart block, is characterized by total AV dissociation with independent atrial and ventricular rhythms and is never benign. Symptoms are more severe when the block is distal in the conduction system. Toxin-induced complete block may resolve once the offending agent is removed.
Etiology And Risk Factors
AV block results from structural conduction system disease, increased refractory periods, or marked shortening of supraventricular cycle length. Inferior wall myocardial infarction commonly causes first-degree and Mobitz type I blocks that are often transient and benign, whereas anterior wall infarction is associated with Mobitz type II block and increased mortality due to ventricular arrhythmias and heart failure. Chronic coronary artery disease may cause fibrosis around the AV node. Drug-related causes include digoxin, beta-blockers, calcium channel blockers, amiodarone, procainamide, class IC antiarrhythmics, and clonidine. Other causes include congenital AV block, valvular disease, surgical trauma following coronary bypass or valve surgery, increased vagal tone, infectious etiologies such as Lyme disease, myocarditis, endocarditis, rheumatic fever, tuberculosis, syphilis, diphtheria, Chagas disease, and toxoplasmosis. Infiltrative and systemic diseases include sarcoidosis, amyloidosis, hemochromatosis, cardiomyopathy, collagen vascular disease, myxedema, hypothermia, and electrolyte disturbances, particularly hyperkalemia.
Pediatric Considerations
AV block occurs in children and is often asymptomatic, though neonatal mortality is highest. Causes include congenital heart disease, maternally acquired antibodies, and infectious myocarditis or rheumatic fever. Toxic ingestions must always be considered in children presenting with new conduction abnormalities.
Clinical Presentation
First-degree AV block is usually asymptomatic. Mobitz type I block may present with pulse irregularity. Mobitz type II and complete heart block commonly cause exercise intolerance, palpitations, chest pain, presyncope or syncope, dyspnea, orthopnea, and altered mental status. Physical findings range from no abnormalities in first-degree block to irregular pulse, hypotension, mental status changes, cyanosis, jugular venous distention, and pulmonary rales in high-grade blocks.
Diagnostic Evaluation
A 12-lead ECG is essential to classify the block and assess for ischemia. First-degree AV block shows a PR interval greater than 0.20 seconds. Mobitz type I demonstrates progressive PR prolongation with cyclic dropped QRS complexes, usually with a narrow QRS. Mobitz type II shows constant PR intervals with intermittent dropped ventricular beats and may have a wide QRS if infranodal. Third-degree block shows independent atrial and ventricular rhythms with fixed PP and RR intervals and variable PR intervals. QRS width depends on the level of the escape rhythm.
Adjunctive Testing
Laboratory studies should target reversible causes and include electrolytes, calcium, magnesium, cardiac enzymes—particularly in Mobitz type II and complete heart block—and digoxin levels when applicable. Chest radiography may reveal cardiomyopathy or heart failure. Echocardiography can identify structural or valvular disease.
Differential Diagnosis
Consider accelerated junctional rhythm, idioventricular rhythm, sinus bradycardia, and sinoatrial block.
Prehospital Management
Unstable patients with Mobitz type II or complete heart block require immediate transcutaneous pacing. Atropine should be avoided in Mobitz type II block and is contraindicated in complete heart block with a wide QRS, as it may worsen conduction. Measures should be taken to avoid increased vagal tone.
Initial Stabilization
Patients with hypoperfusion manifested by hypotension, chest pain, dyspnea, or altered mental status require immediate transcutaneous pacing. Atropine may be used for symptomatic sinus bradycardia or complete heart block with a narrow QRS complex.
Emergency Department Management
First-degree AV block requires no acute treatment; AV nodal blocking agents should be avoided, and evaluation for myocardial infarction, electrolyte abnormalities, or medication toxicity should be performed when indicated. Mobitz type I block usually needs no treatment; atropine may be given if symptomatic. Mobitz type II block requires temporary pacing, either transcutaneous or transvenous, and atropine should not be used. Complete heart block mandates emergent pacing; atropine may provide transient benefit only in narrow-QRS escape rhythms. If toxin-mediated, targeted therapy is required, including digoxin-specific antibodies for digoxin toxicity and glucagon or calcium for beta-blocker or calcium channel blocker overdose.
Medications
Atropine may be given at 0.5–1.0 mg IV every 5 minutes as needed, with pediatric dosing of 0.01–0.03 mg/kg. Digoxin-specific antibody dosing depends on serum level and body weight, with 10 vials often used empirically for severe toxicity. Glucagon is administered at 5–10 mg IV, and calcium chloride at 250–500 mg IV, with weight-based pediatric dosing.
Disposition And Follow-Up
Patients with Mobitz type II or complete heart block require admission to a monitored setting. Asymptomatic first-degree and Mobitz type I block patients may be discharged with outpatient cardiology follow-up.
Clinical Safety Insights
Prompt ECG acquisition in symptomatic patients is critical. Once high-grade AV block is identified, pacing must not be delayed. A thorough history, including medication and toxin exposure, is essential to identify reversible causes. Common errors include misinterpreting ECGs, failing to recognize high-grade block, delaying pacing, and not arranging timely cardiology consultation for permanent pacemaker evaluation.
Overview
Atrioventricular (AV) blocks represent impaired electrical conduction between the atria and ventricles at the level of the AV node or the His–Purkinje system. They are classified by severity and physiologic impact. First-degree AV block involves delayed AV nodal conduction without loss of ventricular beats and is generally benign, occurring in about 1.6% of healthy adults. Second-degree AV block is defined by intermittent failure of atrial impulses to conduct to the ventricles. Mobitz type I (Wenckebach) typically reflects AV nodal disease with progressive PR interval prolongation until a dropped QRS complex and is usually benign, though it may accompany inferior wall myocardial infarction. Mobitz type II reflects infranodal disease with fixed PR intervals and sudden dropped beats, carries a high risk of progression to complete heart block, and has a worse prognosis, particularly with acute myocardial infarction. Third-degree AV block, or complete heart block, is characterized by total AV dissociation with independent atrial and ventricular rhythms and is never benign. Symptoms are more severe when the block is distal in the conduction system. Toxin-induced complete block may resolve once the offending agent is removed.
Etiology And Risk Factors
AV block results from structural conduction system disease, increased refractory periods, or marked shortening of supraventricular cycle length. Inferior wall myocardial infarction commonly causes first-degree and Mobitz type I blocks that are often transient and benign, whereas anterior wall infarction is associated with Mobitz type II block and increased mortality due to ventricular arrhythmias and heart failure. Chronic coronary artery disease may cause fibrosis around the AV node. Drug-related causes include digoxin, beta-blockers, calcium channel blockers, amiodarone, procainamide, class IC antiarrhythmics, and clonidine. Other causes include congenital AV block, valvular disease, surgical trauma following coronary bypass or valve surgery, increased vagal tone, infectious etiologies such as Lyme disease, myocarditis, endocarditis, rheumatic fever, tuberculosis, syphilis, diphtheria, Chagas disease, and toxoplasmosis. Infiltrative and systemic diseases include sarcoidosis, amyloidosis, hemochromatosis, cardiomyopathy, collagen vascular disease, myxedema, hypothermia, and electrolyte disturbances, particularly hyperkalemia.
Pediatric Considerations
AV block occurs in children and is often asymptomatic, though neonatal mortality is highest. Causes include congenital heart disease, maternally acquired antibodies, and infectious myocarditis or rheumatic fever. Toxic ingestions must always be considered in children presenting with new conduction abnormalities.
Clinical Presentation
First-degree AV block is usually asymptomatic. Mobitz type I block may present with pulse irregularity. Mobitz type II and complete heart block commonly cause exercise intolerance, palpitations, chest pain, presyncope or syncope, dyspnea, orthopnea, and altered mental status. Physical findings range from no abnormalities in first-degree block to irregular pulse, hypotension, mental status changes, cyanosis, jugular venous distention, and pulmonary rales in high-grade blocks.
Diagnostic Evaluation
A 12-lead ECG is essential to classify the block and assess for ischemia. First-degree AV block shows a PR interval greater than 0.20 seconds. Mobitz type I demonstrates progressive PR prolongation with cyclic dropped QRS complexes, usually with a narrow QRS. Mobitz type II shows constant PR intervals with intermittent dropped ventricular beats and may have a wide QRS if infranodal. Third-degree block shows independent atrial and ventricular rhythms with fixed PP and RR intervals and variable PR intervals. QRS width depends on the level of the escape rhythm.
Adjunctive Testing
Laboratory studies should target reversible causes and include electrolytes, calcium, magnesium, cardiac enzymes—particularly in Mobitz type II and complete heart block—and digoxin levels when applicable. Chest radiography may reveal cardiomyopathy or heart failure. Echocardiography can identify structural or valvular disease.
Differential Diagnosis
Consider accelerated junctional rhythm, idioventricular rhythm, sinus bradycardia, and sinoatrial block.
Prehospital Management
Unstable patients with Mobitz type II or complete heart block require immediate transcutaneous pacing. Atropine should be avoided in Mobitz type II block and is contraindicated in complete heart block with a wide QRS, as it may worsen conduction. Measures should be taken to avoid increased vagal tone.
Initial Stabilization
Patients with hypoperfusion manifested by hypotension, chest pain, dyspnea, or altered mental status require immediate transcutaneous pacing. Atropine may be used for symptomatic sinus bradycardia or complete heart block with a narrow QRS complex.
Emergency Department Management
First-degree AV block requires no acute treatment; AV nodal blocking agents should be avoided, and evaluation for myocardial infarction, electrolyte abnormalities, or medication toxicity should be performed when indicated. Mobitz type I block usually needs no treatment; atropine may be given if symptomatic. Mobitz type II block requires temporary pacing, either transcutaneous or transvenous, and atropine should not be used. Complete heart block mandates emergent pacing; atropine may provide transient benefit only in narrow-QRS escape rhythms. If toxin-mediated, targeted therapy is required, including digoxin-specific antibodies for digoxin toxicity and glucagon or calcium for beta-blocker or calcium channel blocker overdose.
Medications
Atropine may be given at 0.5–1.0 mg IV every 5 minutes as needed, with pediatric dosing of 0.01–0.03 mg/kg. Digoxin-specific antibody dosing depends on serum level and body weight, with 10 vials often used empirically for severe toxicity. Glucagon is administered at 5–10 mg IV, and calcium chloride at 250–500 mg IV, with weight-based pediatric dosing.
Disposition And Follow-Up
Patients with Mobitz type II or complete heart block require admission to a monitored setting. Asymptomatic first-degree and Mobitz type I block patients may be discharged with outpatient cardiology follow-up.
Clinical Safety Insights
Prompt ECG acquisition in symptomatic patients is critical. Once high-grade AV block is identified, pacing must not be delayed. A thorough history, including medication and toxin exposure, is essential to identify reversible causes. Common errors include misinterpreting ECGs, failing to recognize high-grade block, delaying pacing, and not arranging timely cardiology consultation for permanent pacemaker evaluation.
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Emergency and Acute Medicine – Atrial Fibrillation
Clinical Overview
Atrial fibrillation is a dysrhythmia marked by chaotic atrial electrical activity without effective atrial contraction, caused by multiple reentrant wavelets within the atria. Atrial rates typically range from 350 to 600 beats per minute, resulting in loss of coordinated atrial systole, an irregularly irregular ventricular response, reduced cardiac output, and a significant risk of thromboembolism. It is the most common sustained clinical arrhythmia, with prevalence increasing with age and a higher incidence in men.
Etiology And Risk Factors
Atrial fibrillation commonly arises in the setting of systemic illness, including hypertension, hyperthyroidism, chronic lung disease, infection, pulmonary embolism, hypoxia, electrolyte abnormalities, obesity, thyroid disease, sympathomimetic drug use, and acute alcohol ingestion known as holiday heart syndrome. Cardiac causes include cardiomyopathy, coronary artery disease, valvular disease—particularly mitral pathology—pericarditis, sick sinus syndrome, myocardial contusion, congestive heart failure, and congenital heart disease. In some patients, atrial fibrillation is idiopathic, with no identifiable systemic or structural heart disease on clinical or echocardiographic evaluation.
Clinical Manifestations
Patients may present with palpitations or symptoms related to decreased cardiac output such as weakness, lightheadedness, syncope, hypotension, angina, pulmonary edema, altered mental status, peripheral edema, or a positive hepatojugular reflex. Thromboembolic complications may manifest as acute neurologic deficits or mesenteric ischemia. History should focus on symptom onset, duration, triggering factors, prior episodes, and known cardiac disease. Physical examination classically reveals an irregularly irregular pulse, absence of A waves in the jugular venous pulse, and a pulse deficit in which the apical rate exceeds the peripheral pulse rate at higher ventricular rates.
Initial Evaluation
Assessment begins with history and physical examination to determine hemodynamic stability and the need for immediate cardioversion, as well as estimating symptom duration relative to the 48-hour threshold. Electrocardiography is essential and demonstrates absent P waves replaced by fibrillatory waves with variable morphology and amplitude, an irregularly irregular R–R interval, absence of an isoelectric baseline, and a ventricular rate typically between 80 and 150 beats per minute. Rates exceeding 200 beats per minute with a wide and irregular QRS complex raise concern for an accessory pathway. QRS complexes are usually narrow unless functional aberrancy, preexisting bundle branch block, or preexcitation is present.
Diagnostic Studies
Laboratory testing includes a complete blood count, serum electrolytes, thyroid function tests, cardiac biomarkers when ischemia is suspected, digoxin level if applicable, anticoagulation parameters, and urine toxicology screening when indicated. Chest radiography may assist in evaluating heart failure or pulmonary pathology. Continuous ECG monitoring is required.
Differential Diagnosis
Important considerations include atrial flutter with variable atrioventricular block, multifocal atrial tachycardia, sinus rhythm with frequent premature atrial contractions, and atrial tachycardia with variable conduction.
Prehospital And Immediate Management
Initial care includes intravenous access, oxygen, cardiac monitoring, and prompt synchronized cardioversion in unstable patients. In the emergency department, unstable or life-threatening presentations such as myocardial infarction, pulmonary edema, or refractory heart failure require immediate synchronized electrical cardioversion. Biphasic cardioversion is preferred, starting at 100 joules, while monophasic shocks typically begin at 200 joules.
Rhythm And Rate Control Strategies
For symptom duration under 48 hours, cardioversion may be pursued with consideration of intravenous heparin beforehand. If symptoms exceed 48 hours, anticoagulation is required, transesophageal echocardiography should be performed to exclude atrial thrombus prior to cardioversion, and anticoagulation must continue for four weeks afterward unless emergent cardioversion is required for instability. Chemical cardioversion options include ibutilide, procainamide, flecainide, propafenone, and sotalol, selected based on comorbid conditions such as heart failure, left ventricular hypertrophy, or coronary disease, with careful monitoring for proarrhythmia.
In hemodynamically stable patients, rate control is often preferred when symptom duration exceeds 48 hours, as rhythm control offers no mortality advantage. Rate control is unnecessary if the ventricular rate is below 100 beats per minute or spontaneous conversion occurs. Calcium channel blockers, beta-blockers, or digoxin may be used, except in suspected accessory pathway syndromes such as Wolff–Parkinson–White, where atrioventricular nodal blockers are contraindicated. Procainamide or ibutilide, or electrical cardioversion, are preferred in these cases. Amiodarone may be considered for refractory atrial fibrillation and is the only agent with strong evidence supporting outpatient initiation.
Anticoagulation Considerations
Stroke risk is stratified using the CHADS₂ score, assigning one point each for heart failure, hypertension, age 75 years or older, and diabetes, and two points for prior stroke or transient ischemic attack. A score of zero supports aspirin therapy alone, a score of one allows either aspirin or adjusted-dose warfarin, and scores greater than one require warfarin with a target INR of 2 to 3. Annual stroke risk rises sharply with increasing score. Aspirin is reserved for low-risk patients or those with contraindications to anticoagulation.
Pharmacologic Therapy
Medications used include beta-blockers such as metoprolol, calcium channel blockers such as diltiazem or verapamil, digoxin, amiodarone, procainamide, ibutilide, flecainide, propafenone, sotalol, and anticoagulants including unfractionated heparin, low-molecular-weight heparin, warfarin, and aspirin. Several intravenous antiarrhythmics are not approved for use in the United States and must be administered cautiously with close monitoring.
Disposition And Follow-Up
Admission is indicated for unstable atrial fibrillation, inability to achieve rate control, high stroke risk, associated heart failure, or contributing medical conditions requiring inpatient care. Discharge may be appropriate for patients who convert to sinus rhythm with symptoms under 48 hours, those with chronic atrial fibrillation who achieve adequate rate control and anticoagulation, or new-onset atrial fibrillation with stable control and treatment initiation. Cardiology referral is recommended for outpatient cardioversion or electrophysiologic evaluation. Patients on warfarin require close INR monitoring and should return immediately for symptoms such as syncope, focal neurologic deficits, or visual or speech disturbances.
Key Clinical Insights And Safety Considerations
Synchronized cardioversion is mandatory in hemodynamically unstable atrial fibrillation. Rate and rhythm control should be individualized in stable patients. Misinterpretation of fibrillatory or U waves as P waves can lead to missed diagnosis. Atrioventricular nodal blocking agents must be avoided in atrial fibrillation with wide-complex tachycardia due to an accessory pathway, as they may precipitate ventricular fibrillation.
Clinical Overview
Atrial fibrillation is a dysrhythmia marked by chaotic atrial electrical activity without effective atrial contraction, caused by multiple reentrant wavelets within the atria. Atrial rates typically range from 350 to 600 beats per minute, resulting in loss of coordinated atrial systole, an irregularly irregular ventricular response, reduced cardiac output, and a significant risk of thromboembolism. It is the most common sustained clinical arrhythmia, with prevalence increasing with age and a higher incidence in men.
Etiology And Risk Factors
Atrial fibrillation commonly arises in the setting of systemic illness, including hypertension, hyperthyroidism, chronic lung disease, infection, pulmonary embolism, hypoxia, electrolyte abnormalities, obesity, thyroid disease, sympathomimetic drug use, and acute alcohol ingestion known as holiday heart syndrome. Cardiac causes include cardiomyopathy, coronary artery disease, valvular disease—particularly mitral pathology—pericarditis, sick sinus syndrome, myocardial contusion, congestive heart failure, and congenital heart disease. In some patients, atrial fibrillation is idiopathic, with no identifiable systemic or structural heart disease on clinical or echocardiographic evaluation.
Clinical Manifestations
Patients may present with palpitations or symptoms related to decreased cardiac output such as weakness, lightheadedness, syncope, hypotension, angina, pulmonary edema, altered mental status, peripheral edema, or a positive hepatojugular reflex. Thromboembolic complications may manifest as acute neurologic deficits or mesenteric ischemia. History should focus on symptom onset, duration, triggering factors, prior episodes, and known cardiac disease. Physical examination classically reveals an irregularly irregular pulse, absence of A waves in the jugular venous pulse, and a pulse deficit in which the apical rate exceeds the peripheral pulse rate at higher ventricular rates.
Initial Evaluation
Assessment begins with history and physical examination to determine hemodynamic stability and the need for immediate cardioversion, as well as estimating symptom duration relative to the 48-hour threshold. Electrocardiography is essential and demonstrates absent P waves replaced by fibrillatory waves with variable morphology and amplitude, an irregularly irregular R–R interval, absence of an isoelectric baseline, and a ventricular rate typically between 80 and 150 beats per minute. Rates exceeding 200 beats per minute with a wide and irregular QRS complex raise concern for an accessory pathway. QRS complexes are usually narrow unless functional aberrancy, preexisting bundle branch block, or preexcitation is present.
Diagnostic Studies
Laboratory testing includes a complete blood count, serum electrolytes, thyroid function tests, cardiac biomarkers when ischemia is suspected, digoxin level if applicable, anticoagulation parameters, and urine toxicology screening when indicated. Chest radiography may assist in evaluating heart failure or pulmonary pathology. Continuous ECG monitoring is required.
Differential Diagnosis
Important considerations include atrial flutter with variable atrioventricular block, multifocal atrial tachycardia, sinus rhythm with frequent premature atrial contractions, and atrial tachycardia with variable conduction.
Prehospital And Immediate Management
Initial care includes intravenous access, oxygen, cardiac monitoring, and prompt synchronized cardioversion in unstable patients. In the emergency department, unstable or life-threatening presentations such as myocardial infarction, pulmonary edema, or refractory heart failure require immediate synchronized electrical cardioversion. Biphasic cardioversion is preferred, starting at 100 joules, while monophasic shocks typically begin at 200 joules.
Rhythm And Rate Control Strategies
For symptom duration under 48 hours, cardioversion may be pursued with consideration of intravenous heparin beforehand. If symptoms exceed 48 hours, anticoagulation is required, transesophageal echocardiography should be performed to exclude atrial thrombus prior to cardioversion, and anticoagulation must continue for four weeks afterward unless emergent cardioversion is required for instability. Chemical cardioversion options include ibutilide, procainamide, flecainide, propafenone, and sotalol, selected based on comorbid conditions such as heart failure, left ventricular hypertrophy, or coronary disease, with careful monitoring for proarrhythmia.
In hemodynamically stable patients, rate control is often preferred when symptom duration exceeds 48 hours, as rhythm control offers no mortality advantage. Rate control is unnecessary if the ventricular rate is below 100 beats per minute or spontaneous conversion occurs. Calcium channel blockers, beta-blockers, or digoxin may be used, except in suspected accessory pathway syndromes such as Wolff–Parkinson–White, where atrioventricular nodal blockers are contraindicated. Procainamide or ibutilide, or electrical cardioversion, are preferred in these cases. Amiodarone may be considered for refractory atrial fibrillation and is the only agent with strong evidence supporting outpatient initiation.
Anticoagulation Considerations
Stroke risk is stratified using the CHADS₂ score, assigning one point each for heart failure, hypertension, age 75 years or older, and diabetes, and two points for prior stroke or transient ischemic attack. A score of zero supports aspirin therapy alone, a score of one allows either aspirin or adjusted-dose warfarin, and scores greater than one require warfarin with a target INR of 2 to 3. Annual stroke risk rises sharply with increasing score. Aspirin is reserved for low-risk patients or those with contraindications to anticoagulation.
Pharmacologic Therapy
Medications used include beta-blockers such as metoprolol, calcium channel blockers such as diltiazem or verapamil, digoxin, amiodarone, procainamide, ibutilide, flecainide, propafenone, sotalol, and anticoagulants including unfractionated heparin, low-molecular-weight heparin, warfarin, and aspirin. Several intravenous antiarrhythmics are not approved for use in the United States and must be administered cautiously with close monitoring.
Disposition And Follow-Up
Admission is indicated for unstable atrial fibrillation, inability to achieve rate control, high stroke risk, associated heart failure, or contributing medical conditions requiring inpatient care. Discharge may be appropriate for patients who convert to sinus rhythm with symptoms under 48 hours, those with chronic atrial fibrillation who achieve adequate rate control and anticoagulation, or new-onset atrial fibrillation with stable control and treatment initiation. Cardiology referral is recommended for outpatient cardioversion or electrophysiologic evaluation. Patients on warfarin require close INR monitoring and should return immediately for symptoms such as syncope, focal neurologic deficits, or visual or speech disturbances.
Key Clinical Insights And Safety Considerations
Synchronized cardioversion is mandatory in hemodynamically unstable atrial fibrillation. Rate and rhythm control should be individualized in stable patients. Misinterpretation of fibrillatory or U waves as P waves can lead to missed diagnosis. Atrioventricular nodal blocking agents must be avoided in atrial fibrillation with wide-complex tachycardia due to an accessory pathway, as they may precipitate ventricular fibrillation.
- Published on
Emergency and Acute Medicine – Babesiosis
Overview And Key Concepts
Babesiosis is a tick-borne infection caused by intraerythrocytic protozoa (Babesia spp.) that invade and lyse red blood cells. Illness ranges from asymptomatic infection to severe, life-threatening disease, largely determined by the Babesia species involved and the patient’s immune status. About half of infected children and roughly one-quarter of infected adults may have no symptoms. Mild to moderate illness typically occurs in immunocompetent patients, is often self-limited or responds to antibiotics, and has mortality usually under 5%. Severe disease is commonly defined by prolonged hospitalization (more than 2 weeks), ICU stay (more than 2 days), or death, and is strongly associated with immune compromise such as splenectomy, malignancy, HIV, hemoglobinopathies, or chronic heart, lung, or liver disease. Additional higher-risk groups include neonates, adults older than 50, and patients receiving immunosuppressive medications (including rituximab or anticytokine agents such as etanercept or infliximab). In immunosuppressed patients, mortality may reach about 21%. Complications occur in about half of hospitalized patients, most commonly ARDS and DIC, and may also include CHF, coma, liver failure, renal failure, and splenic rupture. In endemic areas, consider co-infection with other tick-borne illnesses—Lyme disease may present with an associated rash, and human granulocytic anaplasmosis may cause more protracted symptoms with leukopenia.
Causes And Pathophysiology
Human babesiosis is most often due to Babesia microti in the Northern and Midwestern United States (the most common cause in the US), Babesia divergens in Europe, and Babesia duncani on the northern Pacific coast of the US, with reported cases from Asia, Africa, Australia, and South America. Animal reservoirs include white-footed mice and white-tailed deer for B. microti, and cattle and rats for B. divergens. Transmission most commonly occurs via Ixodes ticks; these ticks require a blood meal at each life stage (larva, nymph, adult). Most human cases follow nymph bites in late spring through summer, though adult ticks can also transmit infection. After inoculation, protozoa enter the bloodstream, invade erythrocytes, mature and divide, then exit RBCs—leading to membrane injury, hemolysis, hemoglobinuria, and hemolytic anemia. Damaged RBCs become less deformable and are typically cleared by the spleen; asplenic patients cannot clear infected cells effectively and therefore develop more severe disease. RBC damage may also contribute to microvascular stasis and secondary ischemic injury to organs such as the liver, spleen, heart, kidney, or brain. Transmission can also occur through transfusion of RBCs or platelets; more than 150 transfusion-associated cases have been reported since 1979, with most occurring since 2000. B. microti is the most common transfusion-transmitted pathogen, and donors may have low-level parasitemia that is not visible on smear yet remains infectious; recipients are often immunocompromised or have significant comorbidities, increasing severity. In pediatrics, transmission can occur in utero or during delivery, with cases reported in very young infants (as young as 4 weeks).
Clinical Presentation And Assessment
Symptoms usually begin gradually with malaise and fatigue, along with fever that may reach 105°F (40.6°C), typically 1–4 weeks after a tick bite or 1–9 weeks after transfusion of contaminated blood products. Common symptoms include chills and sweats, headache, anorexia, nonproductive cough, arthralgia, and nausea. Less common features include vomiting, sore throat, abdominal pain, conjunctival injection, photophobia, weight loss, emotional lability, depression, and hyperesthesia. History should specifically address travel to or residence in an endemic region within the prior 2 months (especially spring and summer) and any blood product transfusion within the prior 6 months. Consider babesiosis in shock or sepsis-like presentations when this history is present, particularly if severe-disease risk factors exist. On exam, fever is the most frequent finding; hepatosplenomegaly, pharyngeal erythema, jaundice, and ocular findings (retinopathy with splinter hemorrhages or retinal infarcts) may be present. Rash can occur, including petechiae or ecchymosis; erythema chronicum migrans suggests concurrent Lyme disease. Severe illness may present with tachypnea, hypoxia, hypotension, and altered mental status.
Essential Diagnostic Approach
Diagnosis is primarily established by microscopy of a thin blood smear stained with Giemsa or Wright stain to identify Babesia organisms. If smears are negative, PCR testing can be used. If both microscopy and PCR are negative but suspicion persists, indirect immunofluorescent antibody testing may help by detecting babesial antigens.
Interpretation Of Tests
On microscopy, intraerythrocytic parasites may appear round, oval, or pear-shaped. A budding tetrad (“Maltese cross”) is diagnostic for babesiosis but is not commonly seen. The most typical appearance is intraerythrocytic round or oval (pyriform) ring forms with pale blue cytoplasm and a red-staining nucleus; extracellular parasites may be seen with high parasitemia. Parasitemia is often 1–10% but can be as high as 80%, and may be under 1% early in disease. Ring forms can resemble Plasmodium falciparum malaria, but babesiosis lacks pigment (hemozoin) deposits. PCR amplification of the babesial 18S rRNA gene is more sensitive than microscopy, may return within 24 hours, and is particularly useful when parasitemia is low. Serology via indirect immunofluorescent antibody testing can assist when microscopy and PCR are negative; IgM is usually detectable about 2 weeks after illness onset, IgG titers ≥1:256 suggest recent or active infection, and IgM titers ≥1:64 suggest acute infection. Common nonspecific laboratory abnormalities include hemolytic anemia (low hematocrit/hemoglobin, low haptoglobin, elevated reticulocyte count, elevated LDH, elevated total bilirubin), thrombocytopenia, elevated liver tests (alkaline phosphatase, transaminases, LDH, bilirubin), urinalysis abnormalities (hemoglobinuria and proteinuria), elevated BUN/creatinine suggesting renal impairment, and hyperkalemia from massive hemolysis.
Conditions To Consider
Important alternatives include malaria and other tick-borne illnesses such as Lyme disease, human granulocytic anaplasmosis, ehrlichiosis, Rocky Mountain spotted fever, Colorado tick fever, Q fever, tularemia, relapsing fever, and typhoid fever, as well as other causes of acute hemolytic anemia.
Initial Management And Emergency Care
Prehospital priorities include ensuring airway patency in respiratory distress, providing supplemental oxygen and ventilatory support as needed, and treating shock with IV access and an initial 0.9% normal saline bolus (500 mL in adults; 20 mL/kg in children). In the ED, provide airway and ventilatory support for acute respiratory distress, establish IV access in patients with severe disease or high-risk features, give IV fluids and vasopressors for shock when needed, and place severe cases on cardiac monitoring because cardiac ischemia and arrhythmias can occur. Use antipyretics for fever. Initiate antibiotic therapy in symptomatic patients after confirmation by smear microscopy or PCR.
Definitive Therapy And Medications
For mild to moderate disease, oral atovaquone plus azithromycin for 7–10 days is preferred. Clindamycin plus quinine is an effective alternative but frequently causes adverse effects (tinnitus, vertigo, gastroenteritis) and may require dose reduction or discontinuation in up to one-third of patients. For severe disease, IV clindamycin plus oral quinine for 7–10 days is recommended; IV quinine can be used but may provoke ventricular arrhythmias and requires QT monitoring. RBC exchange transfusion is indicated for parasitemia greater than 10%, hemoglobin less than 10 g/dL, or pulmonary, renal, or hepatic complications. Persistent or relapsing disease can occur in immunocompromised patients; treat for at least 6 weeks and continue therapy for 2 weeks after the last positive smear, using standard regimens. Asymptomatic infection generally does not require antibiotics unless parasitemia persists on smear for more than 3 months. Medication options include acetaminophen 500 mg PO q4–6h (children 10–15 mg/kg per dose; do not exceed 5 doses per 24 hours; adult max 4 g/day), atovaquone 750 mg PO BID for 7 days (children 20 mg/kg per dose; max 750 mg/dose), azithromycin 500 mg PO day 1 then 250 mg PO daily for 6 days (children 10 mg/kg day 1 max 500 mg, then 5 mg/kg daily max 250 mg), clindamycin 300–600 mg IV q6h or 600 mg PO q8h for 7–10 days (children 7–10 mg/kg q6–8h), ibuprofen 400 mg PO q6–8h PRN (children 20–40 mg/kg/day), and quinine 650 mg PO q8h for 7–10 days (children 25 mg/kg/day).
Disposition And Follow-Up Planning
Admit patients with parasitemia above 4%, severe anemia (hemoglobin under 10 g/dL), significant symptoms or complications, or those requiring exchange transfusion, including cases with respiratory distress, hypotension or shock, new renal insufficiency or hepatic failure, altered mental status, or severe hemolysis (jaundice or hematuria). Consider admission even if these are absent when severe-risk features are present; elevated alkaline phosphatase, elevated WBC count, and male sex have been associated with more severe outcomes. Patients with asymptomatic, mild, or moderate disease may be discharged if parasitemia is under 4%, the spleen is intact, the patient is immunocompetent, and oral medications are tolerated. Immunodeficient patients are at increased risk for persistent or relapsing disease and should be referred to infectious disease. Arrange follow-up with primary care or infectious disease to monitor parasitemia after completing antibiotics in symptomatic patients and at 3 months in asymptomatic patients.
Clinical Cautions And Common Errors
Babesiosis can be rapidly fatal in asplenic patients, so maintain a high index of suspicion in this group. Consider babesiosis as a cause of respiratory distress or shock in patients with relevant travel or exposure in endemic regions. Early in infection, blood smears may be negative because parasitemia can be very low, so negative microscopy does not exclude disease when clinical suspicion remains high.
Overview And Key Concepts
Babesiosis is a tick-borne infection caused by intraerythrocytic protozoa (Babesia spp.) that invade and lyse red blood cells. Illness ranges from asymptomatic infection to severe, life-threatening disease, largely determined by the Babesia species involved and the patient’s immune status. About half of infected children and roughly one-quarter of infected adults may have no symptoms. Mild to moderate illness typically occurs in immunocompetent patients, is often self-limited or responds to antibiotics, and has mortality usually under 5%. Severe disease is commonly defined by prolonged hospitalization (more than 2 weeks), ICU stay (more than 2 days), or death, and is strongly associated with immune compromise such as splenectomy, malignancy, HIV, hemoglobinopathies, or chronic heart, lung, or liver disease. Additional higher-risk groups include neonates, adults older than 50, and patients receiving immunosuppressive medications (including rituximab or anticytokine agents such as etanercept or infliximab). In immunosuppressed patients, mortality may reach about 21%. Complications occur in about half of hospitalized patients, most commonly ARDS and DIC, and may also include CHF, coma, liver failure, renal failure, and splenic rupture. In endemic areas, consider co-infection with other tick-borne illnesses—Lyme disease may present with an associated rash, and human granulocytic anaplasmosis may cause more protracted symptoms with leukopenia.
Causes And Pathophysiology
Human babesiosis is most often due to Babesia microti in the Northern and Midwestern United States (the most common cause in the US), Babesia divergens in Europe, and Babesia duncani on the northern Pacific coast of the US, with reported cases from Asia, Africa, Australia, and South America. Animal reservoirs include white-footed mice and white-tailed deer for B. microti, and cattle and rats for B. divergens. Transmission most commonly occurs via Ixodes ticks; these ticks require a blood meal at each life stage (larva, nymph, adult). Most human cases follow nymph bites in late spring through summer, though adult ticks can also transmit infection. After inoculation, protozoa enter the bloodstream, invade erythrocytes, mature and divide, then exit RBCs—leading to membrane injury, hemolysis, hemoglobinuria, and hemolytic anemia. Damaged RBCs become less deformable and are typically cleared by the spleen; asplenic patients cannot clear infected cells effectively and therefore develop more severe disease. RBC damage may also contribute to microvascular stasis and secondary ischemic injury to organs such as the liver, spleen, heart, kidney, or brain. Transmission can also occur through transfusion of RBCs or platelets; more than 150 transfusion-associated cases have been reported since 1979, with most occurring since 2000. B. microti is the most common transfusion-transmitted pathogen, and donors may have low-level parasitemia that is not visible on smear yet remains infectious; recipients are often immunocompromised or have significant comorbidities, increasing severity. In pediatrics, transmission can occur in utero or during delivery, with cases reported in very young infants (as young as 4 weeks).
Clinical Presentation And Assessment
Symptoms usually begin gradually with malaise and fatigue, along with fever that may reach 105°F (40.6°C), typically 1–4 weeks after a tick bite or 1–9 weeks after transfusion of contaminated blood products. Common symptoms include chills and sweats, headache, anorexia, nonproductive cough, arthralgia, and nausea. Less common features include vomiting, sore throat, abdominal pain, conjunctival injection, photophobia, weight loss, emotional lability, depression, and hyperesthesia. History should specifically address travel to or residence in an endemic region within the prior 2 months (especially spring and summer) and any blood product transfusion within the prior 6 months. Consider babesiosis in shock or sepsis-like presentations when this history is present, particularly if severe-disease risk factors exist. On exam, fever is the most frequent finding; hepatosplenomegaly, pharyngeal erythema, jaundice, and ocular findings (retinopathy with splinter hemorrhages or retinal infarcts) may be present. Rash can occur, including petechiae or ecchymosis; erythema chronicum migrans suggests concurrent Lyme disease. Severe illness may present with tachypnea, hypoxia, hypotension, and altered mental status.
Essential Diagnostic Approach
Diagnosis is primarily established by microscopy of a thin blood smear stained with Giemsa or Wright stain to identify Babesia organisms. If smears are negative, PCR testing can be used. If both microscopy and PCR are negative but suspicion persists, indirect immunofluorescent antibody testing may help by detecting babesial antigens.
Interpretation Of Tests
On microscopy, intraerythrocytic parasites may appear round, oval, or pear-shaped. A budding tetrad (“Maltese cross”) is diagnostic for babesiosis but is not commonly seen. The most typical appearance is intraerythrocytic round or oval (pyriform) ring forms with pale blue cytoplasm and a red-staining nucleus; extracellular parasites may be seen with high parasitemia. Parasitemia is often 1–10% but can be as high as 80%, and may be under 1% early in disease. Ring forms can resemble Plasmodium falciparum malaria, but babesiosis lacks pigment (hemozoin) deposits. PCR amplification of the babesial 18S rRNA gene is more sensitive than microscopy, may return within 24 hours, and is particularly useful when parasitemia is low. Serology via indirect immunofluorescent antibody testing can assist when microscopy and PCR are negative; IgM is usually detectable about 2 weeks after illness onset, IgG titers ≥1:256 suggest recent or active infection, and IgM titers ≥1:64 suggest acute infection. Common nonspecific laboratory abnormalities include hemolytic anemia (low hematocrit/hemoglobin, low haptoglobin, elevated reticulocyte count, elevated LDH, elevated total bilirubin), thrombocytopenia, elevated liver tests (alkaline phosphatase, transaminases, LDH, bilirubin), urinalysis abnormalities (hemoglobinuria and proteinuria), elevated BUN/creatinine suggesting renal impairment, and hyperkalemia from massive hemolysis.
Conditions To Consider
Important alternatives include malaria and other tick-borne illnesses such as Lyme disease, human granulocytic anaplasmosis, ehrlichiosis, Rocky Mountain spotted fever, Colorado tick fever, Q fever, tularemia, relapsing fever, and typhoid fever, as well as other causes of acute hemolytic anemia.
Initial Management And Emergency Care
Prehospital priorities include ensuring airway patency in respiratory distress, providing supplemental oxygen and ventilatory support as needed, and treating shock with IV access and an initial 0.9% normal saline bolus (500 mL in adults; 20 mL/kg in children). In the ED, provide airway and ventilatory support for acute respiratory distress, establish IV access in patients with severe disease or high-risk features, give IV fluids and vasopressors for shock when needed, and place severe cases on cardiac monitoring because cardiac ischemia and arrhythmias can occur. Use antipyretics for fever. Initiate antibiotic therapy in symptomatic patients after confirmation by smear microscopy or PCR.
Definitive Therapy And Medications
For mild to moderate disease, oral atovaquone plus azithromycin for 7–10 days is preferred. Clindamycin plus quinine is an effective alternative but frequently causes adverse effects (tinnitus, vertigo, gastroenteritis) and may require dose reduction or discontinuation in up to one-third of patients. For severe disease, IV clindamycin plus oral quinine for 7–10 days is recommended; IV quinine can be used but may provoke ventricular arrhythmias and requires QT monitoring. RBC exchange transfusion is indicated for parasitemia greater than 10%, hemoglobin less than 10 g/dL, or pulmonary, renal, or hepatic complications. Persistent or relapsing disease can occur in immunocompromised patients; treat for at least 6 weeks and continue therapy for 2 weeks after the last positive smear, using standard regimens. Asymptomatic infection generally does not require antibiotics unless parasitemia persists on smear for more than 3 months. Medication options include acetaminophen 500 mg PO q4–6h (children 10–15 mg/kg per dose; do not exceed 5 doses per 24 hours; adult max 4 g/day), atovaquone 750 mg PO BID for 7 days (children 20 mg/kg per dose; max 750 mg/dose), azithromycin 500 mg PO day 1 then 250 mg PO daily for 6 days (children 10 mg/kg day 1 max 500 mg, then 5 mg/kg daily max 250 mg), clindamycin 300–600 mg IV q6h or 600 mg PO q8h for 7–10 days (children 7–10 mg/kg q6–8h), ibuprofen 400 mg PO q6–8h PRN (children 20–40 mg/kg/day), and quinine 650 mg PO q8h for 7–10 days (children 25 mg/kg/day).
Disposition And Follow-Up Planning
Admit patients with parasitemia above 4%, severe anemia (hemoglobin under 10 g/dL), significant symptoms or complications, or those requiring exchange transfusion, including cases with respiratory distress, hypotension or shock, new renal insufficiency or hepatic failure, altered mental status, or severe hemolysis (jaundice or hematuria). Consider admission even if these are absent when severe-risk features are present; elevated alkaline phosphatase, elevated WBC count, and male sex have been associated with more severe outcomes. Patients with asymptomatic, mild, or moderate disease may be discharged if parasitemia is under 4%, the spleen is intact, the patient is immunocompetent, and oral medications are tolerated. Immunodeficient patients are at increased risk for persistent or relapsing disease and should be referred to infectious disease. Arrange follow-up with primary care or infectious disease to monitor parasitemia after completing antibiotics in symptomatic patients and at 3 months in asymptomatic patients.
Clinical Cautions And Common Errors
Babesiosis can be rapidly fatal in asplenic patients, so maintain a high index of suspicion in this group. Consider babesiosis as a cause of respiratory distress or shock in patients with relevant travel or exposure in endemic regions. Early in infection, blood smears may be negative because parasitemia can be very low, so negative microscopy does not exclude disease when clinical suspicion remains high.
- Published on
Emergency And Acute Medicine – Altered Mental Status
Foundational Overview
Altered mental status (AMS) results from dysfunction of the reticular activating system in the upper brainstem or from widespread involvement of one or both cerebral hemispheres. It represents a spectrum of impaired consciousness and cognition rather than a single diagnosis. Clinical states range from mild confusion to coma. Confusion reflects reduced clarity, coherence, and reasoning. Drowsiness describes difficulty maintaining alertness. Lethargy refers to globally depressed awareness despite apparent wakefulness. Stupor requires vigorous stimulation for arousal, while coma denotes complete unresponsiveness to stimuli. Delirium is characterized by an acute, fluctuating disturbance in attention and consciousness, often progressing rapidly.
Causative Categories
Hypoxic causes include severe pulmonary disease, anemia, shock, and intracardiac shunting, particularly in pediatric patients. Metabolic abnormalities are common and include hypoglycemia, hyperglycemia, diabetic ketoacidosis, electrolyte disturbances, renal failure, hepatic encephalopathy, acid–base disorders, dehydration, and vitamin deficiencies. Toxicologic causes encompass sedatives, narcotics, toxic alcohols, salicylates, anticonvulsants, psychotropics, carbon monoxide, cyanide, heavy metals, and drug withdrawal syndromes, especially alcohol and sedatives.
Infectious etiologies include urinary tract infection in the elderly, pneumonia, sepsis, meningitis, encephalitis, and brain abscess. Endocrine disorders such as myxedema coma, thyrotoxicosis, adrenal disease, and parathyroid disorders may contribute. Environmental exposures include hypothermia, heat stroke, high-altitude cerebral edema, neuroleptic malignant syndrome, and malignant hyperthermia. Vascular, neurologic, autoimmune, traumatic, psychiatric, and multifactorial causes—particularly in older adults—must also be considered.
Clinical Features And Examination Findings
Patients often present with confusion, inattention, memory impairment, and disorganized thinking. Impaired cognition may be evident through difficulty with orientation, recall, calculations, object naming, or serial tasks. Fever may suggest infection, drug toxicity, or endocrine disorders. Severe hypertension with bradycardia may indicate increased intracranial pressure. Hypotension raises concern for infection, toxins, or cardiac causes.
Eye movement abnormalities such as ocular bobbing or ocular dipping may point to brainstem or diffuse cortical injury. Pupillary reflexes are typically preserved in metabolic or toxic coma but may be abnormal with focal neurologic pathology. Additional focal findings include hemiparesis, aphasia, seizures, nuchal rigidity, and asterixis. A careful history from witnesses, family, or prehospital providers is essential, along with a comprehensive physical and neurologic examination.
Initial Diagnostic Assessment
Evaluation begins with bedside glucose testing, complete blood count, electrolytes, renal function tests, and toxicology screening. Additional studies may include coagulation testing, liver function tests, thyroid studies, ammonia levels, serum osmolarity, and arterial blood gas analysis. Blood and urine cultures are obtained when infection is suspected.
Neuroimaging with noncontrast head CT is essential to exclude hemorrhage or mass effect. Chest radiography may identify pneumonia. MRI is indicated when ischemic stroke or other intracranial pathology is suspected and may be deferred to inpatient evaluation. Lumbar puncture is warranted if the cause remains unclear after imaging and laboratory testing, with empiric antibiotics administered beforehand if meningitis is suspected. EEG is useful for suspected seizures or nonconvulsive status epilepticus.
Conditions To Differentiate
Locked-in syndrome presents with preserved consciousness but quadriplegia and mutism, with communication possible through eye movements. Psychogenic unresponsiveness includes conversion disorders, catatonia, malingering, and akinetic mutism. Dementia differs in that attention is often preserved early, with gradual cognitive decline rather than acute fluctuation.
Prehospital And Early Emergency Care
Initial management prioritizes airway protection, oxygenation, IV access, cardiac monitoring, and spinal immobilization when trauma is possible. The traditional “coma cocktail” includes dextrose, naloxone, and thiamine. A focused neurologic assessment, documentation of vital signs, and inspection for trauma or medical alert identifiers are essential. Empiric dextrose should not be delayed if glucose testing is unavailable, and glucose administration is safe prior to thiamine.
Emergency Department Management
Patients with undifferentiated AMS may require empiric broad-spectrum antibiotics with good cerebrospinal fluid penetration. Suspected toxic ingestions warrant targeted antidotal therapy. Temperature abnormalities should be corrected promptly. Definitive treatment focuses on identifying and reversing the underlying cause while providing supportive care.
Disposition And Ongoing Care
All patients with acute or persistent changes in mental status require hospital admission. Discharge may be appropriate for patients with transient, fully resolved causes such as treated hypoglycemia or uncomplicated drug intoxication without risk of delayed toxicity. Chronic AMS without deviation from baseline may also be managed outpatient. Follow-up should address the underlying etiology, including medication adjustment or substance use treatment when indicated.
Key Clinical Lessons And Common Errors
Always prioritize reversible causes such as hypoglycemia, opioid toxicity, and thiamine deficiency. Maintain a low threshold for neuroimaging in patients with unclear causes or focal neurologic deficits. Consider empiric antibiotics in febrile patients or when the etiology is uncertain. Delays in identifying treatable causes and failure to reassess evolving neurologic findings are frequent and avoidable pitfalls.
Foundational Overview
Altered mental status (AMS) results from dysfunction of the reticular activating system in the upper brainstem or from widespread involvement of one or both cerebral hemispheres. It represents a spectrum of impaired consciousness and cognition rather than a single diagnosis. Clinical states range from mild confusion to coma. Confusion reflects reduced clarity, coherence, and reasoning. Drowsiness describes difficulty maintaining alertness. Lethargy refers to globally depressed awareness despite apparent wakefulness. Stupor requires vigorous stimulation for arousal, while coma denotes complete unresponsiveness to stimuli. Delirium is characterized by an acute, fluctuating disturbance in attention and consciousness, often progressing rapidly.
Causative Categories
Hypoxic causes include severe pulmonary disease, anemia, shock, and intracardiac shunting, particularly in pediatric patients. Metabolic abnormalities are common and include hypoglycemia, hyperglycemia, diabetic ketoacidosis, electrolyte disturbances, renal failure, hepatic encephalopathy, acid–base disorders, dehydration, and vitamin deficiencies. Toxicologic causes encompass sedatives, narcotics, toxic alcohols, salicylates, anticonvulsants, psychotropics, carbon monoxide, cyanide, heavy metals, and drug withdrawal syndromes, especially alcohol and sedatives.
Infectious etiologies include urinary tract infection in the elderly, pneumonia, sepsis, meningitis, encephalitis, and brain abscess. Endocrine disorders such as myxedema coma, thyrotoxicosis, adrenal disease, and parathyroid disorders may contribute. Environmental exposures include hypothermia, heat stroke, high-altitude cerebral edema, neuroleptic malignant syndrome, and malignant hyperthermia. Vascular, neurologic, autoimmune, traumatic, psychiatric, and multifactorial causes—particularly in older adults—must also be considered.
Clinical Features And Examination Findings
Patients often present with confusion, inattention, memory impairment, and disorganized thinking. Impaired cognition may be evident through difficulty with orientation, recall, calculations, object naming, or serial tasks. Fever may suggest infection, drug toxicity, or endocrine disorders. Severe hypertension with bradycardia may indicate increased intracranial pressure. Hypotension raises concern for infection, toxins, or cardiac causes.
Eye movement abnormalities such as ocular bobbing or ocular dipping may point to brainstem or diffuse cortical injury. Pupillary reflexes are typically preserved in metabolic or toxic coma but may be abnormal with focal neurologic pathology. Additional focal findings include hemiparesis, aphasia, seizures, nuchal rigidity, and asterixis. A careful history from witnesses, family, or prehospital providers is essential, along with a comprehensive physical and neurologic examination.
Initial Diagnostic Assessment
Evaluation begins with bedside glucose testing, complete blood count, electrolytes, renal function tests, and toxicology screening. Additional studies may include coagulation testing, liver function tests, thyroid studies, ammonia levels, serum osmolarity, and arterial blood gas analysis. Blood and urine cultures are obtained when infection is suspected.
Neuroimaging with noncontrast head CT is essential to exclude hemorrhage or mass effect. Chest radiography may identify pneumonia. MRI is indicated when ischemic stroke or other intracranial pathology is suspected and may be deferred to inpatient evaluation. Lumbar puncture is warranted if the cause remains unclear after imaging and laboratory testing, with empiric antibiotics administered beforehand if meningitis is suspected. EEG is useful for suspected seizures or nonconvulsive status epilepticus.
Conditions To Differentiate
Locked-in syndrome presents with preserved consciousness but quadriplegia and mutism, with communication possible through eye movements. Psychogenic unresponsiveness includes conversion disorders, catatonia, malingering, and akinetic mutism. Dementia differs in that attention is often preserved early, with gradual cognitive decline rather than acute fluctuation.
Prehospital And Early Emergency Care
Initial management prioritizes airway protection, oxygenation, IV access, cardiac monitoring, and spinal immobilization when trauma is possible. The traditional “coma cocktail” includes dextrose, naloxone, and thiamine. A focused neurologic assessment, documentation of vital signs, and inspection for trauma or medical alert identifiers are essential. Empiric dextrose should not be delayed if glucose testing is unavailable, and glucose administration is safe prior to thiamine.
Emergency Department Management
Patients with undifferentiated AMS may require empiric broad-spectrum antibiotics with good cerebrospinal fluid penetration. Suspected toxic ingestions warrant targeted antidotal therapy. Temperature abnormalities should be corrected promptly. Definitive treatment focuses on identifying and reversing the underlying cause while providing supportive care.
Disposition And Ongoing Care
All patients with acute or persistent changes in mental status require hospital admission. Discharge may be appropriate for patients with transient, fully resolved causes such as treated hypoglycemia or uncomplicated drug intoxication without risk of delayed toxicity. Chronic AMS without deviation from baseline may also be managed outpatient. Follow-up should address the underlying etiology, including medication adjustment or substance use treatment when indicated.
Key Clinical Lessons And Common Errors
Always prioritize reversible causes such as hypoglycemia, opioid toxicity, and thiamine deficiency. Maintain a low threshold for neuroimaging in patients with unclear causes or focal neurologic deficits. Consider empiric antibiotics in febrile patients or when the etiology is uncertain. Delays in identifying treatable causes and failure to reassess evolving neurologic findings are frequent and avoidable pitfalls.
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Emergency and Acute Medicine – Airway Management
Overview
Airway management encompasses techniques used to ensure adequate oxygenation and ventilation in critically ill or injured patients. It is a core skill in emergency medicine and includes basic airway maneuvers, airway adjuncts, definitive intubation, and surgical airway access. The priority is oxygenation and ventilation rather than intubation alone.
Basic Airway Adjuncts
Oral and nasopharyngeal airways lift the tongue off the hypopharynx and facilitate bag-valve-mask ventilation. Oropharyngeal airways require an absent gag reflex, whereas nasopharyngeal airways may be used when the gag reflex is intact.
Rapid Sequence Intubation (RSI)
RSI is the preferred ED method for oral intubation because it minimizes aspiration risk and optimizes intubating conditions through rapid induction and paralysis. It is contraindicated when paralysis is unsafe or when a difficult airway is anticipated without a reliable rescue plan. A preformulated backup strategy is essential.
Awake and Assisted Intubation Techniques
Awake oral intubation uses sedation without paralysis and is indicated when neuromuscular blockade is contraindicated. Ketamine is commonly used, often with benzodiazepines. A gum elastic bougie is helpful when vocal cords are poorly visualized, with tracheal placement suggested by tactile contact with tracheal rings.
Alternative Airway Devices
Extraglottic devices are inserted blindly into the oropharynx for rapid airway control. Laryngeal mask airways form a seal around glottic structures but provide less aspiration protection than endotracheal tubes. Intubating LMAs allow endotracheal tube placement. Esophageal–tracheal tubes such as the Combitube or King LT ventilate the hypopharynx while occluding the esophagus.
Advanced Visualization Techniques
Video laryngoscopes and fiberoptic devices improve visualization of the airway and are useful in patients with anatomic limitations or cervical spine instability. These techniques are less effective when blood or secretions obscure the airway and are contraindicated when immediate airway control is required.
Nasotracheal Intubation
Nasotracheal intubation is useful when oral access is impaired, oral intubation fails, or paralysis is contraindicated. Absolute contraindication is apnea. Relative contraindications include anticoagulation, massive facial trauma, upper airway abscess, epiglottitis, and penetrating neck injury.
Surgical Airways
Cricothyrotomy is the definitive rescue airway for failed intubation and ventilation. It is indicated in crash airways, massive facial trauma, or complete upper airway obstruction. Percutaneous translaryngeal ventilation may provide temporary oxygenation while preparing for cricothyrotomy.
Indications for Airway Intervention
Airway intervention is required when patients cannot maintain or protect the airway, develop hypoxia or ventilatory failure, or are expected to deteriorate. Common indications include altered mental status, status epilepticus, severe trauma, and the need for controlled ventilation during procedures.
Airway Assessment
A difficult airway should be anticipated using structured assessment such as the LEMON approach, evaluating external anatomy, mouth opening, mandibular and thyromental distance, Mallampati class, obstruction, and neck mobility. Early recognition guides appropriate technique selection and backup planning.
Verification of Tube Placement
Direct visualization of the tube passing through the vocal cords is the gold standard. End-tidal CO₂ monitoring is the most reliable bedside confirmation. Auscultation, chest rise, tube condensation, and pulse oximetry trends are supportive but less reliable. Chest radiography confirms depth and complications but does not exclude esophageal intubation.
Emergency Department Management
RSI requires thorough preparation, preoxygenation, appropriate positioning, and rapid confirmation of tube placement. Adequate postintubation sedation and, if needed, continued paralysis are essential. Failed attempts require immediate transition to alternative airway devices or surgical airway access.
Disposition
Most intubated patients require ICU admission. Rarely, selected patients intubated briefly for airway protection or diagnostic procedures may be extubated in the ED after observation and discharged safely.
Pearls and Pitfalls
Failure to ventilate is immediately life-threatening. Always assess for a difficult airway and establish a backup plan before intervention. Prioritize oxygenation and ventilation over intubation, and escalate early to alternative or surgical airway techniques when standard approaches fail.
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Emergency and Acute Medicine – Alcoholic ketoacidosis
Basics description
Alcoholic ketoacidosis is caused by increased ketone body production resulting from dehydration due to nausea and vomiting with inhibition of antidiuretic hormone, leading to elevated stress hormone release and ketogenesis. Hepatic glycogen stores are depleted because of malnutrition or reduced carbohydrate intake. Ethanol metabolism increases the NADH/NAD ratio, promoting free fatty acid production and favoring β-hydroxybutyrate over acetoacetate as the predominant ketone.
Etiology
Alcoholic ketoacidosis typically occurs in malnourished chronic alcohol users following a recent episode of heavy alcohol consumption. Nausea, vomiting, or abdominal pain lead to abrupt cessation of alcohol intake. Presentation usually occurs within 12–72 hours.
Diagnosis signs and symptoms
Dehydration is common. Fever is usually absent unless infection is present. Tachycardia frequently occurs due to hypovolemia with orthostatic changes and concurrent alcohol withdrawal. Tachypnea is common, often with deep, rapid Kussmaul respirations. Nausea, vomiting, and abdominal pain are the most frequent symptoms and are usually diffuse with nonspecific tenderness; epigastric pain is common. Rebound tenderness, abdominal distension, and hypoactive bowel sounds are uncommon and should prompt evaluation for alternative pathology. Urine output is decreased due to hypovolemia. Mental status is typically minimally altered; significant alteration requires evaluation for head injury, cerebrovascular accident, intracranial hemorrhage, hypoglycemia, alcohol withdrawal, encephalopathy, or toxic ingestion. Visual disturbances may occur.
History often reveals chronic alcohol use with a recent binge followed by abrupt cessation. Physical examination commonly shows dehydration, ketotic breath odor, Kussmaul respirations, and palmar erythema.
Essential workup
An increased anion gap metabolic acidosis due to ketone accumulation should be identified. Toxic alcohol ingestion and other causes of anion gap metabolic acidosis must be excluded.
Diagnosis tests and interpretation
Laboratory findings demonstrate increased anion gap metabolic acidosis as the hallmark. Mixed acid–base disorders are common and may include respiratory alkalosis, metabolic alkalosis from vomiting, hyperchloremic acidosis, and mild lactic acidosis related to dehydration and ethanol metabolism. Severe lactic acidosis suggests alternative pathology such as hypoxia, seizures, or shock. Urine and serum nitroprusside tests are positive but underestimate severity because β-hydroxybutyrate predominates and is not detected; results may paradoxically increase during treatment. Electrolyte abnormalities include low bicarbonate, hypokalemia, hypocalcemia, hypophosphatemia, and hypomagnesemia. Glucose levels are usually normal or mildly elevated, though hypoglycemia may occur. Alcohol levels may be negative. BUN and creatinine are mildly elevated due to dehydration. CBC may show mild leukocytosis, anemia, and thrombocytopenia related to chronic alcohol use. Urinalysis shows ketonuria without glucosuria. Amylase and lipase may be elevated with pancreatitis. Liver enzymes may be mildly elevated. The osmolal gap may be increased; values greater than 20 mOsm/kg warrant evaluation for methanol or ethylene glycol ingestion, correcting for ethanol by dividing the ethanol level by 4.6.
Chest radiography is indicated if pneumonia is suspected. Abdominal imaging is considered for acute abdomen. CT of the head is required with trauma or unexplained altered mental status.
Differential diagnosis
Causes of elevated anion gap metabolic acidosis include alcoholic ketoacidosis, toxic ingestions, acetaminophen toxicity, fulminant hepatic failure, antiretroviral toxicity, toluene, methanol, metformin, uremia, diabetic ketoacidosis, paraldehyde, iron, isoniazid, lactic acidosis, ethylene glycol, salicylates, and starvation ketosis. Other considerations include hypovolemia from GI bleeding or sepsis and abdominal pain from pancreatitis, gastritis, hepatitis, perforated ulcer, alcohol withdrawal, viral illness, or bowel obstruction.
Treatment pre hospital
Provide supportive care with IV access, 0.9% normal saline, oxygen, and cardiac monitoring. Evaluate for toxic ingestion, diabetic history, and coexisting illness such as gastrointestinal bleeding.
Initial stabilization therapy
Initiate cardiac monitoring and supplemental oxygen. Administer naloxone, thiamine, and dextrose if mental status is altered. Begin IV normal saline with a 500 mL–1 L bolus and continue resuscitation as needed to promote renal ketone clearance.
Ed treatment procedures
Administer antiemetics and benzodiazepines for alcohol withdrawal. Begin dextrose-containing fluids such as D5NS, which resolve metabolic abnormalities more rapidly than saline alone by restoring glycogen stores and stimulating endogenous insulin. Avoid dextrose if significant hyperglycemia is present. Administer IV thiamine before glucose to prevent Wernicke encephalopathy. Sodium bicarbonate is rarely indicated and reserved for severe acidosis with cardiovascular compromise. Anticipate and correct electrolyte shifts, particularly hypokalemia, hypophosphatemia, and hypomagnesemia. Insulin is not indicated and may cause hypoglycemia.
Medication
Dextrose 50%: 25 g IV
Lorazepam: 2 mg IV, titrate to effect
Naloxone: 2 mg IV
Ondansetron: 4–8 mg IV
Prochlorperazine: 5–10 mg IV slowly
Promethazine: 12.5–25 mg IV
Thiamine: 100 mg IV
Follow up disposition
Admission is indicated for persistent metabolic acidosis, hypovolemia, ongoing vomiting, unclear abdominal pain, comorbid illness, or electrolyte abnormalities requiring monitoring. Many patients can be managed in an observation unit for 12–24 hours if tolerating oral intake, metabolic abnormalities resolve, and no additional illness is present.
Follow up recommendations
Provide counseling and referral for alcohol cessation.
Pearls and pitfalls
Aggressive volume resuscitation with dextrose-containing fluids is essential. Always administer thiamine before glucose. Monitor electrolytes and glucose closely. Evaluate unexplained elevated osmolal gaps. Continuous cardiac monitoring is required due to the risk of dysrhythmias, electrolyte disturbances, and alcoholic cardiomyopathy.
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Emergency and Acute Medicine – Alcohol Poisoning
BASICS DESCRIPTION
Alcohol is the most commonly abused recreational agent among emergency department patients. Alcohol is frequently associated with traumatic injuries.
ETIOLOGY
Alcohol intoxication: Directly depresses CNS function. Blood alcohol levels drop by 15–40 mg/dL/hr depending on individual variables and chronicity of alcohol use.
Alcohol withdrawal: Occurs in chronic alcohol abusers after partial or complete alcohol abstinence. May occur despite a serum alcohol level >100 mg/dL (e.g., “intoxicated”). Primarily due to loss of chronic CNS inhibition: profound CNS excitation with increased catecholamine release and adrenergic tone.
DIAGNOSIS SIGNS AND SYMPTOMS
Acute alcohol intoxication: CNS effects occur on a spectrum including relaxation, euphoria, sedation, memory loss, impaired judgment, ataxia, slurred speech, obtundation, or coma. May also cause GI upset.
Alcohol withdrawal syndrome:
Early or minor withdrawal: <8 hr after last drink—symptoms of hangover, headache, nausea />omiting. At 12 hr—mild tremors/anxiety, anorexia, nausea, vomiting, weakness, myalgias, vivid dreams/nightmares.
12–36 hr after last drink—irritability/agitation, tachycardia/HTN, tremors in hands and tongue.
24–48 hr—alcoholic hallucinosis with visual hallucinations most common (bug crawling) and auditory hallucinations (buzzing, clicks).
Alcohol withdrawal seizures: 8–12 hr after last drink; brief, spontaneously abating tonic–clonic activity; often precede delirium tremens (DTs).
Late or major withdrawal: ≥48 hr after last drink—DTs characterized by clouded consciousness, confusion, agitation/combativeness, tachycardia/HTN, hyperpyrexia, and diaphoresis.
History is often provided by EMS, family, or friends. Beware the “frequent flyer” in the ED, as other causes of AMS may coexist, including hepatic encephalopathy, postictal state, hypoglycemia, head injury, or intracranial bleeding.
Physical exam: Vital signs—acute intoxication usually normal or depressed; withdrawal usually elevated. Mental status—acute intoxication presents with somnolence or coma; withdrawal presents with hyperalert agitation. Signs of hepatic injury include jaundice, icterus, spider angiomata, asterixis, and hepatomegaly. Signs of malnutrition include alopecia, poor dentition, poor muscle mass, abdominal wasting, and temporal wasting.
ESSENTIAL WORKUP
Obtain accurate alcohol ingestion and abstinence history. Investigate life-threatening causes of seizures including hypoglycemia (rapid bedside glucose), intracranial hemorrhage, CNS infection, and electrolyte abnormalities. Evaluate for occult trauma. Monitor vital signs frequently; hyperthermia predicts poorer outcomes.
DIAGNOSTIC TESTS & INTERPRETATION
Labs: Alcohol level if abnormal mental status; urine toxicology for coingestants; electrolytes, BUN, creatinine, glucose; CBC; magnesium, calcium, phosphate; PT/INR if coagulopathy suspected; LFTs if liver disease suspected; ammonia if hepatic encephalopathy suspected; urinary ketones or serum acetone if alcoholic ketoacidosis suspected.
Imaging: CT head if mental status is disproportionate to alcohol level, head trauma suspected, focal neurologic findings, signs of increased ICP, new-onset seizure, or deterioration. EEG differentiates alcohol withdrawal seizures from epilepsy. Chest radiograph if aspiration or pneumonia suspected.
DIFFERENTIAL DIAGNOSIS
Acute intoxication: Hypoglycemia, CO₂ narcosis, mixed-drug overdose, ethylene glycol, methanol, isopropanol poisoning, hepatic encephalopathy, psychosis, severe vertigo, psychomotor seizure.
Withdrawal/seizures: Sedative–hypnotic withdrawal, carbon monoxide poisoning, isoniazid toxicity, amphetamines, anticholinergics, cocaine.
Secondary seizure disorders: Infection, meningitis, encephalitis, brain abscess, trauma, intracranial hemorrhage, CVA, tumor, anticonvulsant noncompliance, thyroid disease.
TREATMENT PRE HOSPITAL
Administer benzodiazepines for seizures. Give naloxone, oxygen, and dextrose for comatose patients. Intubate as needed for airway protection. Immobilize cervical spine if trauma suspected.
INITIAL STABILIZATION/THERAPY
Airway, breathing, circulation (ABCs). Evaluate cervical spine. Initiate IV rehydration with 0.9% NS, then D5 0.45 NS. Administer naloxone, thiamine, and glucose (or Accu-Chek) if altered mental status. Treat seizures with benzodiazepines, often requiring large doses.
Pediatric considerations: Young children have decreased hepatic glycogen reserves and may not mount an adequate glucose response. Rapid bedside glucose is essential; administer dextrose with D5 (10 mL/kg), D10 (5 mL/kg), or D25 (2 mL/kg) depending on age and size.
ED TREATMENT/PROCEDURES
Alcohol intoxication: IV rehydration and correction of electrolyte abnormalities including magnesium, potassium, folate, thiamine, and multivitamins.
Alcoholic ketoacidosis: Aggressive rehydration with D5 0.9 NS; exclude other causes of anion-gap metabolic acidosis.
Alcohol withdrawal syndrome: Use CIWA-Ar scale to assess severity and guide symptom-triggered therapy. Benzodiazepines are first-line; large, frequent doses may be required. Phenobarbital may be used for severe or refractory withdrawal. Propofol is indicated for intubated patients with refractory seizures. β-blockers and α-agonists may normalize vital signs but do not treat CNS complications. Phenytoin is not indicated unless seizures are unrelated to withdrawal.
MEDICATION
Dextrose: D50W 1 amp (50 mL or 25 g); peds D25W 2–4 mL/kg IV.
Diazepam: 5–10 mg IV q5–10 min until calm.
Lorazepam: 0.5–4 mg IV/IM q5–10 min until calm.
Naloxone: 0.4–2 mg IV/IM (peds 0.1 mg/kg).
Phenobarbital: 10–20 mg/kg IV loading dose.
Phenytoin: 15–18 mg/kg (max 25 mg/min); fosphenytoin 15–20 mgPE/kg.
Propofol: 25–75 µg/kg/min loading, then 5–50 µg/kg/min maintenance.
Thiamine: 100 mg IV/IM (peds 50 mg).
FOLLOW-UP DISPOSITION
Admission criteria: Uncontrolled seizures or withdrawal, hepatic failure, infection, dehydration, malnutrition, cardiovascular collapse, dysrhythmia, trauma, hallucinations, abnormal vital signs, severe agitation, Wernicke encephalopathy, confusion, or delirium.
Discharge criteria: Clinically sober and seizure-free for 6 hr with negative workup if first seizure.
FOLLOW-UP RECOMMENDATIONS
Substance abuse referral for patients with recurrent alcohol intoxication or use.
PEARLS AND PITFALLS
Do not attribute AMS solely to alcohol in chronic users. Serum alcohol should fall by 15–40 mg/dL/hr; lack of improvement warrants further evaluation. Inadequate benzodiazepine dosing is common—massive doses may be required. Hypoglycemia frequently mimics intoxication and is common in chronic alcoholics and children.
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Emergency and Acute Medicine – Agitation
Overview and Definition
Agitation is a state of extreme restlessness marked by increased verbal activity, motor activity, or both. It represents a broad clinical spectrum ranging from excessive talkativeness to aggressive, threatening, or violent behavior. Agitation may be the presenting feature of numerous medical (organic) or psychiatric (functional) conditions and therefore requires careful and systematic evaluation in the emergency setting.
Clinical Significance and Special Forms
Agitation varies widely in severity and includes life-threatening entities such as excited delirium syndrome. This condition is characterized by severe agitation, metabolic acidosis, and hyperadrenergic autonomic dysfunction, and is associated with a risk of sudden cardiac death, particularly following prolonged physical struggle or restraint. Early recognition and intervention are critical to reduce morbidity and mortality.
Epidemiology
Behavioral disturbances account for approximately 6% of all emergency department visits, translating to an estimated 1.7 million visits annually in the United States. Agitated patients frequently require significant ED resources and pose safety challenges for staff and other patients.
Etiology
Agitation has a wide differential diagnosis. Medical causes include infections such as meningitis, encephalitis, and sepsis-related delirium; metabolic disturbances including hypoglycemia, electrolyte abnormalities, renal or hepatic failure, and acid–base disorders; endocrine emergencies such as thyroid storm; pulmonary causes including hypoxia and hypercapnia; toxicologic causes such as intoxication or withdrawal states; and neurologic disorders including stroke, intracranial hemorrhage, postictal states, or brain tumors. Psychiatric causes include mood disorders (mania or agitated depression), psychotic disorders such as schizophrenia, and severe anxiety disorders.
History and Clinical Assessment
A detailed history and physical examination are essential in distinguishing organic from functional causes of agitation. The history of present illness alone has high sensitivity for detecting underlying medical illness in patients presenting with psychiatric symptoms. When the patient is unable to provide a reliable history, collateral information should be obtained from family, friends, emergency medical services, or caregivers. Key historical points include trauma, recent infection, medication use, substance exposure, psychiatric history, and neurologic symptoms.
Physical Examination
A comprehensive physical examination is mandatory. Abnormal vital signs should prompt an aggressive search for medical causes. Hyperthermia may suggest infection, neuroleptic malignant syndrome, serotonin syndrome, or excited delirium. A toxidrome-oriented examination should include pupillary size, skin findings, sweating patterns, and urinary retention. A focused but thorough neurologic examination is critical, as focal deficits mandate evaluation for structural or metabolic disease. Cognitive testing is particularly important, as impaired attention, memory, or orientation suggests delirium rather than a purely psychiatric disorder.
Diagnostic Evaluation
The extent of diagnostic testing should be guided by clinical suspicion. At a minimum, all agitated patients require a full set of vital signs, a complete physical and neurologic examination, and bedside blood glucose testing. Additional laboratory studies, imaging, or procedures should be tailored to suspected etiologies. Head CT imaging is indicated in patients with trauma or neurologic deficits, while lumbar puncture should be considered when CNS infection is suspected and no source is otherwise identified.
Prehospital and Initial Management
Prehospital providers should follow established protocols for physical and chemical restraint and provide advance notification to the receiving facility. Initial emergency department management focuses on airway, breathing, and circulation, with prompt treatment of any life-threatening conditions. Severely agitated patients may pose immediate danger and should be placed in a controlled environment, changed into hospital attire, and searched for weapons to ensure safety.
Management of Agitation
Treatment should be directed at the underlying cause whenever possible. Verbal de-escalation techniques are first-line therapy for mild to moderate agitation. When pharmacologic intervention is required, benzodiazepines are preferred for alcohol withdrawal, while antipsychotics are first-line for agitation due to primary psychiatric disorders. Combination therapy may be necessary for severe agitation. Physical restraints should be used only when necessary and always in conjunction with chemical sedation to minimize complications.
Disposition and Follow-Up
Disposition depends on the etiology and resolution of agitation. Admission is indicated when an underlying medical or psychiatric condition requires inpatient management. Discharge should be reserved for patients whose agitation has resolved and who can be safely managed as outpatients. Appropriate psychiatric or substance-use referrals should be arranged, and follow-up tailored to the underlying diagnosis.
Pearls and Pitfalls
Clinicians must maintain a high index of suspicion for medical causes of agitation, particularly in patients with new onset after age 45, abnormal vital signs, focal neurologic deficits, acute onset, visual hallucinations, or impaired cognition. Common pitfalls include failure to undress and search patients for weapons, inadequate sedation, prolonged or poorly monitored restraint use, and insufficient documentation of clinical decision-making and restraint justification.
