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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 – 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 – Ankle Fracture/Dislocation
Basics – Description
Common mechanisms and injury patterns of the ankle include inversion, eversion, external rotation, combined mechanisms (e.g., Maisonneuve fracture), and inversion with dorsiflexion (snowboarder’s fracture). These mechanisms result in predictable patterns of malleolar, fibular, syndesmotic, or talar injuries. Most ankle fractures involve the malleoli and are common in young males and women aged 50–70 years. Risk factors include cigarette use and elevated BMI. Pediatric ankle fractures frequently involve the physis and may result in growth disturbances.
Diagnosis – Signs And Symptoms
Patients typically present with a history of trauma, ankle pain, swelling, deformity, and inability to bear weight. Soft tissue swelling, ecchymosis, skin tenting, or blanching may be present. Neurovascular compromise should be assessed carefully, including capillary refill and dorsalis pedis/posterior tibial pulses. A detailed history should determine the position of the ankle at injury, ability to bear weight afterward, and any audible “pop” or “snap.”
Physical Examination
The Ottawa Ankle Rules are highly sensitive for determining the need for imaging and are reliable in children older than 5 years. Examination should include inspection of the skin, assessment of distal neurovascular status, palpation of the proximal fibula when indicated, and evaluation of motor and sensory function.
Diagnosis – Tests And Interpretation
Radiographs should include AP, lateral, and mortise views, with additional tibia/fibula views if a Maisonneuve fracture is suspected. Post-reduction imaging is required for unstable fractures or dislocations. CT or MRI may be used to further evaluate tibial plafond or ligamentous injury
Treatment
Prehospital Care
Immobilize the ankle to limit pain, bleeding, and further injury. Avoid traction devices and do not attempt reduction of protruding bone.
Initial Stabilization And Therapy
Non–weight bearing, ice, compression, and elevation are essential.
ED Treatment And Procedures
All ankle fractures and dislocations require orthopedic referral. Open fractures require antibiotics, tetanus prophylaxis, and emergent consultation. Closed dislocations should be reduced promptly and immobilized with appropriate splinting. Stable injuries may be managed conservatively, while unstable injuries often require operative fixation.
Medications
Analgesics are the mainstay for closed fractures. Procedural sedation may be required for reductions. Open fractures require IV antibiotics and tetanus prophylaxis.
Follow-Up And Disposition
Unstable fractures, open injuries, dislocations, or neurovascular compromise require admission. Stable, nondisplaced fractures may be discharged with splinting and close orthopedic follow-up.
Key Clinical Insights And Common Errors
When reducing a dislocated ankle, partial flexion of the knee helps relax the Achilles tendon and decreases resistance during manipulation. Careful examination is necessary to differentiate ankle fractures from subtalar injuries, as subtalar dislocations are uncommon and often difficult to reduce. Clinicians should remain vigilant for associated injuries, including trauma to the lumbar spine, hip, tibia, fibula—especially the proximal fibular neck—and the foot, which may otherwise be overlooked.
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Emergency And Acute Medicine – Alkalosis
Core Overview
Alkalosis refers to disorders in which blood pH is elevated above normal. This may occur due to excessive loss of carbon dioxide from hyperventilation (respiratory alkalosis) or from an increase in serum bicarbonate concentration (metabolic alkalosis). Respiratory alkalosis results from increased alveolar ventilation leading to reduced PaCO₂, commonly triggered by hypoxemia, metabolic acidosis, or direct stimulation of central or peripheral chemoreceptors. It is rarely life-threatening and typically occurs with pH values below 7.50.
Metabolic alkalosis develops when hydrogen ions are lost or bicarbonate is gained. Persistence requires impaired renal excretion of bicarbonate, often due to volume depletion, electrolyte abnormalities, or hormonal influences. Severe alkalemia carries high mortality, particularly when pH exceeds 7.55–7.65.
Underlying Causes
Respiratory alkalosis may arise from central nervous system conditions such as anxiety, pain, fever, stroke, infection, or intracranial lesions. Hypoxemia from altitude exposure, anemia, or pulmonary shunting is a frequent trigger. Drugs and hormones including salicylates, catecholamines, nicotine, progesterone, pregnancy, and hyperthyroidism may also contribute. Thoracic conditions such as pulmonary embolism, pneumonia, pneumothorax, sepsis, hepatic failure, and heat exhaustion are additional causes.
Metabolic alkalosis is commonly due to gastrointestinal hydrogen loss from vomiting, nasogastric suction, bulimia, or chloride-losing diarrhea. Renal losses occur with diuretics, mineralocorticoid excess, post-hypercapnia states, and inherited tubulopathies such as Bartter or Gitelman syndromes. Other mechanisms include intracellular hydrogen shifts, extracellular volume contraction, bicarbonate administration, and massive transfusions.
Clinical Manifestations
Symptoms result from reduced cerebral blood flow, electrolyte disturbances, and the underlying disease process. Neuromuscular irritability due to hypocalcemia is common and may present with weakness, myalgias, tetany, paresthesias, carpal–pedal spasm, seizures, or altered mental status. Cardiac arrhythmias may occur in association with hypokalemia. Signs of dehydration, hypoxemia, and neuromuscular excitability such as Chvostek or Trousseau signs may be present.
Initial Evaluation
Assessment begins with serum electrolytes demonstrating elevated bicarbonate in metabolic alkalosis and evaluation for hypokalemia or hypocalcemia. Renal function testing helps identify dehydration or renal failure. Blood gas analysis confirms alkalemia and distinguishes respiratory from metabolic causes. Expected compensatory responses should be calculated to detect mixed acid–base disorders. Measurement of urine chloride is essential in metabolic alkalosis to differentiate saline-responsive from saline-resistant causes.
Diagnostic Studies
Additional laboratory testing may include glucose, ionized calcium, magnesium, pregnancy testing, and targeted studies based on clinical suspicion such as CBC, cultures, liver function tests, aspirin levels, toxicology screening, renin, aldosterone, cortisol, and thyroid studies. Imaging with chest radiography may reveal pulmonary or cardiac pathology. Electrocardiography is useful for identifying conduction abnormalities related to electrolyte disturbances.
Conditions To Consider
Respiratory alkalosis requires exclusion of organic pathology before diagnosing anxiety-related hyperventilation. Metabolic alkalosis may be categorized as saline responsive (e.g., gastric losses, diuretics, post-hypercapnia states) or saline resistant (e.g., hyperaldosteronism, Cushing syndrome, inherited renal disorders, exogenous alkali exposure).
Emergency Management Principles
Initial stabilization focuses on airway, breathing, and circulation with oxygen, IV access, and cardiac monitoring. Altered mental status warrants administration of glucose, thiamine, and naloxone as indicated.
Respiratory alkalosis is managed by treating the underlying cause, with cautious use of anxiolytics when appropriate.
Management of metabolic alkalosis depends on urine chloride. Volume-depleted patients benefit from isotonic saline and potassium repletion. Saline-resistant cases require treatment of the underlying endocrine or renal disorder, potassium supplementation, aldosterone antagonists, or acetazolamide. Severe refractory alkalosis may rarely require dilute hydrochloric acid infusion or hemodialysis.
Pharmacologic Therapy
Therapeutic agents may include dextrose for hypoglycemia, potassium supplementation, naloxone, thiamine, acetazolamide, spironolactone, antiemetics, and proton pump inhibitors. Dilute hydrochloric acid infusion is reserved for life-threatening alkalemia and must be administered via a central line with close monitoring.
Disposition And Follow-Up
Hospital admission is required for severe alkalemia, altered mental status, dysrhythmias, significant electrolyte abnormalities, hemodynamic instability, or serious underlying disease. ICU care is indicated for pH values greater than 7.55. Patients may be discharged once alkalosis resolves and contributing factors are corrected.
Key Clinical Insights And Common Errors
Respiratory alkalosis is driven by increased minute ventilation resulting in low PaCO₂ and elevated pH. Metabolic alkalosis typically reflects increased bicarbonate retention due to volume, potassium, or chloride depletion. Contraction alkalosis occurs with extracellular fluid loss concentrating serum bicarbonate. Mixed acid–base disorders should be suspected when pH appears normal despite abnormal PaCO₂ or bicarbonate, or when compensatory responses are inappropriate.
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Emergency And Acute Medicine – Amebiasis
Core Overview
Amebiasis is an invasive parasitic infection with both intestinal and extraintestinal manifestations. It is endemic worldwide, particularly in regions with poor sanitation. High-risk populations include travelers to or immigrants from endemic areas, institutionalized individuals, men who have sex with men, individuals engaging in oral–anal sexual practices, and those with HIV infection. Severe disease and complications are more likely in immunocompromised patients, pregnant or postpartum individuals, those at extremes of age, and patients with malnutrition or malignancy.
Causative Organism And Transmission
The disease is caused by Entamoeba histolytica, an anaerobic, nonflagellated protozoan. Humans are the sole reservoir. Transmission occurs via the fecal–oral route, leading to invasive colitis after ingestion. Extraintestinal spread occurs hematogenously.
Clinical Manifestations
Intestinal disease typically presents 1 week to 1 month after exposure. Most cases involve acute nondysenteric colitis with afebrile diarrhea and minimal abdominal findings. Classic dysentery presents with bloody, mucoid diarrhea, abdominal pain, tenesmus, and weight loss, with fever being uncommon. Fulminant colitis manifests with severe toxicity, rigid abdomen, high risk of perforation, and mortality exceeding 40%. Toxic megacolon presents with profuse diarrhea, fever, abdominal distension, and peritonitis, often associated with corticosteroid use. Chronic complications include ameboma, amebic strictures, and chronic colitis.
Extraintestinal disease most commonly involves amebic liver abscess, typically a solitary lesion in the right lobe. Patients present with fever, right upper quadrant pain, hepatomegaly, and minimal diarrhea. Complications include rupture into pleural, peritoneal, or pericardial spaces. Rare manifestations include brain, lung, splenic, perinephric, genital, and cutaneous amebiasis.
History And Physical Examination
A careful exposure history and assessment of risk factors are essential. Physical examination should focus on identifying signs of dehydration, peritonitis, sepsis, shock, abdominal masses, or hepatomegaly. Digital rectal examination frequently reveals gross or occult blood.
Diagnostic Evaluation
Stool PCR is the diagnostic gold standard with near-perfect sensitivity and specificity. Stool antigen testing and serology are valuable adjuncts, particularly in suspected liver abscess where stool studies may be negative. Stool microscopy is no longer recommended due to poor sensitivity. Laboratory findings may include leukocytosis, elevated alkaline phosphatase and ALT in liver abscess, and electrolyte abnormalities from dehydration.
Imaging with abdominal ultrasound or CT is used to identify liver abscesses and assess rupture risk. Colonoscopy with biopsy provides definitive diagnosis for colitis, dysentery, ameboma, and strictures. Fine-needle aspiration of liver abscess is reserved for diagnostic uncertainty or treatment failure.
Conditions To Differentiate
Intestinal amebiasis must be distinguished from enteroinvasive bacterial infections, inflammatory bowel disease, ischemic colitis, malignancy, pancreatitis, and bowel obstruction. Liver abscess should be differentiated from bacterial abscess, echinococcal cyst, tuberculosis, malignancy, and cholecystitis. Cutaneous disease may mimic carcinoma or sexually transmitted infections.
Initial Stabilization And Supportive Care
Management begins with airway, breathing, and circulation assessment. Intravenous isotonic fluids are indicated for dehydration or shock. Antidiarrheal agents should be avoided. Electrolyte abnormalities must be corrected promptly.
Definitive Emergency Department Management
Systemic therapy with metronidazole or tinidazole is first-line for invasive disease. All patients must receive subsequent luminal therapy to eradicate intestinal colonization. Luminal agents should never be used alone. If stool and serology are negative but suspicion remains high, gastroenterology consultation and repeat testing are warranted. Surgical intervention is required for toxic megacolon, perforation, or refractory disease. Liver abscesses may require drainage if large, left-sided, ruptured, or unresponsive to medical therapy.
Special Population Considerations
In pregnancy, metronidazole should be used cautiously in the first trimester but not withheld in life-threatening disease. Certain agents, including tinidazole and tetracycline, are contraindicated. Pediatric patients are at higher risk for fulminant colitis and require careful monitoring.
Disposition And Follow-Up
Hospital admission is indicated for patients with shock, sepsis, peritonitis, severe dehydration, electrolyte imbalance, fulminant colitis, bowel obstruction, extraintestinal abscesses, or failure of outpatient therapy. Discharge may be appropriate for stable patients with mild disease who can tolerate oral therapy. Follow-up with gastroenterology or infectious disease is recommended within one week.
Key Clinical Lessons And Common Errors
Avoid antidiarrheal medications in suspected amebiasis. Always treat with both a systemic amebicide and a luminal agent unless contraindicated. Maintain vigilance for high-mortality complications such as fulminant colitis and extraintestinal disease, as delayed recognition significantly worsens outcomes.
Core Overview
Amebiasis is an invasive parasitic infection with both intestinal and extraintestinal manifestations. It is endemic worldwide, particularly in regions with poor sanitation. High-risk populations include travelers to or immigrants from endemic areas, institutionalized individuals, men who have sex with men, individuals engaging in oral–anal sexual practices, and those with HIV infection. Severe disease and complications are more likely in immunocompromised patients, pregnant or postpartum individuals, those at extremes of age, and patients with malnutrition or malignancy.
Causative Organism And Transmission
The disease is caused by Entamoeba histolytica, an anaerobic, nonflagellated protozoan. Humans are the sole reservoir. Transmission occurs via the fecal–oral route, leading to invasive colitis after ingestion. Extraintestinal spread occurs hematogenously.
Clinical Manifestations
Intestinal disease typically presents 1 week to 1 month after exposure. Most cases involve acute nondysenteric colitis with afebrile diarrhea and minimal abdominal findings. Classic dysentery presents with bloody, mucoid diarrhea, abdominal pain, tenesmus, and weight loss, with fever being uncommon. Fulminant colitis manifests with severe toxicity, rigid abdomen, high risk of perforation, and mortality exceeding 40%. Toxic megacolon presents with profuse diarrhea, fever, abdominal distension, and peritonitis, often associated with corticosteroid use. Chronic complications include ameboma, amebic strictures, and chronic colitis.
Extraintestinal disease most commonly involves amebic liver abscess, typically a solitary lesion in the right lobe. Patients present with fever, right upper quadrant pain, hepatomegaly, and minimal diarrhea. Complications include rupture into pleural, peritoneal, or pericardial spaces. Rare manifestations include brain, lung, splenic, perinephric, genital, and cutaneous amebiasis.
History And Physical Examination
A careful exposure history and assessment of risk factors are essential. Physical examination should focus on identifying signs of dehydration, peritonitis, sepsis, shock, abdominal masses, or hepatomegaly. Digital rectal examination frequently reveals gross or occult blood.
Diagnostic Evaluation
Stool PCR is the diagnostic gold standard with near-perfect sensitivity and specificity. Stool antigen testing and serology are valuable adjuncts, particularly in suspected liver abscess where stool studies may be negative. Stool microscopy is no longer recommended due to poor sensitivity. Laboratory findings may include leukocytosis, elevated alkaline phosphatase and ALT in liver abscess, and electrolyte abnormalities from dehydration.
Imaging with abdominal ultrasound or CT is used to identify liver abscesses and assess rupture risk. Colonoscopy with biopsy provides definitive diagnosis for colitis, dysentery, ameboma, and strictures. Fine-needle aspiration of liver abscess is reserved for diagnostic uncertainty or treatment failure.
Conditions To Differentiate
Intestinal amebiasis must be distinguished from enteroinvasive bacterial infections, inflammatory bowel disease, ischemic colitis, malignancy, pancreatitis, and bowel obstruction. Liver abscess should be differentiated from bacterial abscess, echinococcal cyst, tuberculosis, malignancy, and cholecystitis. Cutaneous disease may mimic carcinoma or sexually transmitted infections.
Initial Stabilization And Supportive Care
Management begins with airway, breathing, and circulation assessment. Intravenous isotonic fluids are indicated for dehydration or shock. Antidiarrheal agents should be avoided. Electrolyte abnormalities must be corrected promptly.
Definitive Emergency Department Management
Systemic therapy with metronidazole or tinidazole is first-line for invasive disease. All patients must receive subsequent luminal therapy to eradicate intestinal colonization. Luminal agents should never be used alone. If stool and serology are negative but suspicion remains high, gastroenterology consultation and repeat testing are warranted. Surgical intervention is required for toxic megacolon, perforation, or refractory disease. Liver abscesses may require drainage if large, left-sided, ruptured, or unresponsive to medical therapy.
Special Population Considerations
In pregnancy, metronidazole should be used cautiously in the first trimester but not withheld in life-threatening disease. Certain agents, including tinidazole and tetracycline, are contraindicated. Pediatric patients are at higher risk for fulminant colitis and require careful monitoring.
Disposition And Follow-Up
Hospital admission is indicated for patients with shock, sepsis, peritonitis, severe dehydration, electrolyte imbalance, fulminant colitis, bowel obstruction, extraintestinal abscesses, or failure of outpatient therapy. Discharge may be appropriate for stable patients with mild disease who can tolerate oral therapy. Follow-up with gastroenterology or infectious disease is recommended within one week.
Key Clinical Lessons And Common Errors
Avoid antidiarrheal medications in suspected amebiasis. Always treat with both a systemic amebicide and a luminal agent unless contraindicated. Maintain vigilance for high-mortality complications such as fulminant colitis and extraintestinal disease, as delayed recognition significantly worsens outcomes.
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Emergency And Acute Medicine – Angioedema
Core Description
Angioedema is a nonpruritic, well-demarcated, nonpitting swelling of the deeper dermis and subcutaneous tissues caused by increased vascular permeability. It results from inflammatory mediator release, either mast cell mediated or kinin mediated through bradykinin and complement pathways. Unlike urticaria, angioedema affects deeper tissues with fewer mast cells and nerve endings, leading to minimal itching. In addition to the skin, angioedema may involve the gastrointestinal tract and upper airway, and it may occur with or without associated urticaria.
Pathophysiologic Mechanisms
Hereditary and acquired forms of angioedema are related to quantitative or functional deficiencies of C1 esterase inhibitor (C1-INH), resulting in unregulated bradykinin activity. Hereditary angioedema is an autosomal dominant disorder with multiple genetic variants, while acquired forms are associated with lymphoproliferative or autoimmune disease. Angiotensin-converting enzyme inhibitor–related angioedema is common in emergency settings and may occur early or years after initiation of therapy.
Underlying Causes
Kinin-mediated etiologies include hereditary angioedema, acquired C1-INH deficiency, and ACE inhibitor–associated reactions. Mast cell–mediated causes include food allergies, medication reactions, insect stings, and physical triggers such as exercise, temperature changes, or trauma. Idiopathic recurrent angioedema and autoimmune-associated forms are also recognized.
Clinical Features
Patients typically present with sudden, asymmetric swelling of the lips, eyelids, face, tongue, or extremities. Lesions are large, nonpitting, and nonpruritic. Abdominal involvement may cause severe pain, nausea, vomiting, or diarrhea. Airway involvement involving the pharynx or larynx is the most dangerous manifestation and may progress rapidly. Attacks of hereditary angioedema are notably not associated with urticaria or itching.
History And Physical Assessment
A careful history should assess family history, recurrent episodes, recent medication use (especially ACE inhibitors), food exposures, and prior similar events. Emotional stress or minor trauma may precipitate attacks. Physical examination focuses on identifying airway compromise, facial and oropharyngeal swelling, and abdominal tenderness. Lesions typically spare gravity-dependent areas.
Diagnostic Approach
Angioedema is primarily a clinical diagnosis. A family history may be absent, as new mutations account for a significant proportion of hereditary cases. Laboratory testing may support the diagnosis but is not required acutely.
Laboratory And Specialized Testing
Basic studies may include a complete blood count and inflammatory markers. Complement levels such as C4 are often reduced during attacks in hereditary and acquired forms. Measurement of C1-INH levels and function confirms hereditary angioedema but is rarely available in the emergency department. Skin biopsy is rarely required.
Differential Considerations
Conditions that may mimic angioedema include superior vena cava syndrome, heart failure, nephrotic syndrome, facial cellulitis, contact dermatitis, autoimmune connective tissue diseases, hypothyroidism, and facial lymphedema.
Emergency Management Principles
Early airway protection is the priority in all cases. Intravenous access and close monitoring are essential. Epinephrine, antihistamines, and corticosteroids are commonly used when mast cell–mediated angioedema is suspected, though response may be limited in bradykinin-mediated disease. Early intubation should be strongly considered if there is progressive airway involvement.
Targeted Therapy
Hereditary and acquired angioedema may require C1-INH replacement, bradykinin receptor antagonists, or kallikrein inhibitors. Fresh frozen plasma may be used when specific agents are unavailable, though caution is advised. ACE inhibitor–induced angioedema requires immediate discontinuation of the offending drug.
Disposition And Follow-Up
Patients with airway involvement or persistent systemic symptoms require admission and monitored care. Those with mild, nonprogressive symptoms may be discharged after observation with antihistamines, steroids, and clear return precautions. Referral to an allergist or immunologist is recommended for recurrent, hereditary, or unexplained cases.
Clinical Pearls And Pitfalls
Airway compromise can evolve rapidly and unpredictably, necessitating early intervention. Standard allergic therapies may be ineffective in bradykinin-mediated angioedema. Recognition of hereditary angioedema and ACE inhibitor–related cases is critical to avoid delayed or ineffective treatment.
Core Description
Angioedema is a nonpruritic, well-demarcated, nonpitting swelling of the deeper dermis and subcutaneous tissues caused by increased vascular permeability. It results from inflammatory mediator release, either mast cell mediated or kinin mediated through bradykinin and complement pathways. Unlike urticaria, angioedema affects deeper tissues with fewer mast cells and nerve endings, leading to minimal itching. In addition to the skin, angioedema may involve the gastrointestinal tract and upper airway, and it may occur with or without associated urticaria.
Pathophysiologic Mechanisms
Hereditary and acquired forms of angioedema are related to quantitative or functional deficiencies of C1 esterase inhibitor (C1-INH), resulting in unregulated bradykinin activity. Hereditary angioedema is an autosomal dominant disorder with multiple genetic variants, while acquired forms are associated with lymphoproliferative or autoimmune disease. Angiotensin-converting enzyme inhibitor–related angioedema is common in emergency settings and may occur early or years after initiation of therapy.
Underlying Causes
Kinin-mediated etiologies include hereditary angioedema, acquired C1-INH deficiency, and ACE inhibitor–associated reactions. Mast cell–mediated causes include food allergies, medication reactions, insect stings, and physical triggers such as exercise, temperature changes, or trauma. Idiopathic recurrent angioedema and autoimmune-associated forms are also recognized.
Clinical Features
Patients typically present with sudden, asymmetric swelling of the lips, eyelids, face, tongue, or extremities. Lesions are large, nonpitting, and nonpruritic. Abdominal involvement may cause severe pain, nausea, vomiting, or diarrhea. Airway involvement involving the pharynx or larynx is the most dangerous manifestation and may progress rapidly. Attacks of hereditary angioedema are notably not associated with urticaria or itching.
History And Physical Assessment
A careful history should assess family history, recurrent episodes, recent medication use (especially ACE inhibitors), food exposures, and prior similar events. Emotional stress or minor trauma may precipitate attacks. Physical examination focuses on identifying airway compromise, facial and oropharyngeal swelling, and abdominal tenderness. Lesions typically spare gravity-dependent areas.
Diagnostic Approach
Angioedema is primarily a clinical diagnosis. A family history may be absent, as new mutations account for a significant proportion of hereditary cases. Laboratory testing may support the diagnosis but is not required acutely.
Laboratory And Specialized Testing
Basic studies may include a complete blood count and inflammatory markers. Complement levels such as C4 are often reduced during attacks in hereditary and acquired forms. Measurement of C1-INH levels and function confirms hereditary angioedema but is rarely available in the emergency department. Skin biopsy is rarely required.
Differential Considerations
Conditions that may mimic angioedema include superior vena cava syndrome, heart failure, nephrotic syndrome, facial cellulitis, contact dermatitis, autoimmune connective tissue diseases, hypothyroidism, and facial lymphedema.
Emergency Management Principles
Early airway protection is the priority in all cases. Intravenous access and close monitoring are essential. Epinephrine, antihistamines, and corticosteroids are commonly used when mast cell–mediated angioedema is suspected, though response may be limited in bradykinin-mediated disease. Early intubation should be strongly considered if there is progressive airway involvement.
Targeted Therapy
Hereditary and acquired angioedema may require C1-INH replacement, bradykinin receptor antagonists, or kallikrein inhibitors. Fresh frozen plasma may be used when specific agents are unavailable, though caution is advised. ACE inhibitor–induced angioedema requires immediate discontinuation of the offending drug.
Disposition And Follow-Up
Patients with airway involvement or persistent systemic symptoms require admission and monitored care. Those with mild, nonprogressive symptoms may be discharged after observation with antihistamines, steroids, and clear return precautions. Referral to an allergist or immunologist is recommended for recurrent, hereditary, or unexplained cases.
Clinical Pearls And Pitfalls
Airway compromise can evolve rapidly and unpredictably, necessitating early intervention. Standard allergic therapies may be ineffective in bradykinin-mediated angioedema. Recognition of hereditary angioedema and ACE inhibitor–related cases is critical to avoid delayed or ineffective treatment.
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Emergency And Acute Medicine – Anaphylaxis
Clinical Overview
Anaphylaxis is an acute, life-threatening systemic hypersensitivity reaction that develops rapidly after exposure to an antigen in a sensitized individual. It represents a form of distributive shock caused by widespread mediator release, leading to vasodilation, increased vascular permeability, smooth-muscle contraction, and excessive glandular secretion. These physiologic changes result in reduced systemic vascular resistance, decreased venous return and cardiac output, and intravascular volume depletion. Anaphylaxis accounts for hundreds of deaths annually in the United States and thousands of emergency department visits each month.
Underlying Causes
IgE-mediated reactions are most commonly triggered by antibiotics (particularly penicillins), insect venoms, foods such as peanuts, shellfish, and tree nuts, latex, vaccines, and monoclonal antibody therapies. Non–IgE-mediated reactions may occur with iodine-based contrast agents, opiates, and vancomycin.
Special Considerations In Children: Food allergens—especially milk, egg, wheat, soy, and peanuts—are the most frequent triggers, and even trace exposures may provoke severe reactions.
Clinical Manifestations
Symptoms typically begin within minutes of antigen exposure. Skin and mucosal involvement is present in the vast majority of cases, with urticaria, erythema, pruritus, and angioedema being common. Patients may report an early sense of impending doom. Respiratory findings range from nasal congestion to bronchospasm and upper airway edema. Cardiovascular involvement may include hypotension, arrhythmias, or myocardial ischemia. Gastrointestinal symptoms such as nausea, vomiting, and diarrhea may occur, along with ocular irritation, neurologic symptoms including seizures, and, rarely, hematologic abnormalities such as coagulopathy.
Key Historical Features
Diagnosis is clinical. A focused history should identify prior allergic reactions, known triggers, and recent exposures to foods, medications, or environmental allergens.
Physical Examination Focus
Findings usually involve two or more organ systems, commonly the skin, respiratory tract, gastrointestinal tract, or cardiovascular system. Airway compromise or hypotension may not be present initially but can develop rapidly.
Essential Clinical Assessment
Anaphylaxis is diagnosed on clinical grounds, and early recognition is critical. Ancillary testing should not delay treatment. ECG monitoring is advised in patients with cardiac history, ischemic symptoms, or advanced age.
Diagnostic Evaluation
Laboratory studies are generally not useful in the acute setting. Serum tryptase levels may aid retrospective confirmation. Chest radiography may show hyperinflation in cases with bronchospasm.
Alternative Diagnoses To Consider
Conditions that may mimic anaphylaxis include pulmonary embolism, acute coronary syndromes, asthma, airway obstruction, vasovagal syncope, hereditary angioedema, systemic mastocytosis, hypoglycemia, carcinoid syndrome, and foreign body aspiration.
Prehospital Care Principles
Early airway assessment, oxygen supplementation, IV access, and continuous monitoring are essential. Intramuscular epinephrine should be administered promptly, even before IV access is obtained. Progressive laryngeal edema may necessitate early airway intervention.
Immediate Stabilization Measures
Airway protection and adequate ventilation take priority. Orotracheal intubation is preferred when airway compromise is anticipated. Advanced airway techniques may be required in the presence of significant edema. Epinephrine may be administered via IM, IV, or endotracheal routes, along with aggressive fluid resuscitation.
Emergency Department Management
Continuous cardiac and vital-sign monitoring is required. Persistent bronchospasm is treated with inhaled β2-agonists. Hypotension is addressed with IV fluids and vasopressors if needed. Antihistamines reduce histamine-mediated effects, corticosteroids help prevent biphasic reactions, and glucagon is indicated for epinephrine-resistant anaphylaxis in patients taking β-blockers.
Pharmacologic Therapy
First-line therapy includes intramuscular epinephrine, H1 antihistamines, corticosteroids, and inhaled bronchodilators. Second-line agents include racemic epinephrine, H2 blockers, and glucagon when indicated. Special caution is required in patients receiving β-blockers.
Disposition Planning
Patients requiring intubation or ongoing respiratory or hemodynamic support should be admitted to an intensive care setting. Those with persistent or severe reactions warrant inpatient observation due to the risk of biphasic reactions. Patients with complete symptom resolution may be discharged after a period of observation.
Post-Discharge Follow-Up
All patients should receive early outpatient follow-up, ideally with an allergist. Education regarding trigger avoidance and prescription of self-injectable epinephrine are essential. Patients should be instructed on proper auto-injector use and advised to carry it at all times.
Clinical Pearls And Pitfalls
Delayed recognition of anaphylaxis can result in rapid airway compromise and cardiovascular collapse. Early administration of epinephrine is the single most critical intervention. Patients with a prior history of anaphylaxis require education on avoidance strategies and prompt self-treatment to prevent fatal outcomes.
Clinical Overview
Anaphylaxis is an acute, life-threatening systemic hypersensitivity reaction that develops rapidly after exposure to an antigen in a sensitized individual. It represents a form of distributive shock caused by widespread mediator release, leading to vasodilation, increased vascular permeability, smooth-muscle contraction, and excessive glandular secretion. These physiologic changes result in reduced systemic vascular resistance, decreased venous return and cardiac output, and intravascular volume depletion. Anaphylaxis accounts for hundreds of deaths annually in the United States and thousands of emergency department visits each month.
Underlying Causes
IgE-mediated reactions are most commonly triggered by antibiotics (particularly penicillins), insect venoms, foods such as peanuts, shellfish, and tree nuts, latex, vaccines, and monoclonal antibody therapies. Non–IgE-mediated reactions may occur with iodine-based contrast agents, opiates, and vancomycin.
Special Considerations In Children: Food allergens—especially milk, egg, wheat, soy, and peanuts—are the most frequent triggers, and even trace exposures may provoke severe reactions.
Clinical Manifestations
Symptoms typically begin within minutes of antigen exposure. Skin and mucosal involvement is present in the vast majority of cases, with urticaria, erythema, pruritus, and angioedema being common. Patients may report an early sense of impending doom. Respiratory findings range from nasal congestion to bronchospasm and upper airway edema. Cardiovascular involvement may include hypotension, arrhythmias, or myocardial ischemia. Gastrointestinal symptoms such as nausea, vomiting, and diarrhea may occur, along with ocular irritation, neurologic symptoms including seizures, and, rarely, hematologic abnormalities such as coagulopathy.
Key Historical Features
Diagnosis is clinical. A focused history should identify prior allergic reactions, known triggers, and recent exposures to foods, medications, or environmental allergens.
Physical Examination Focus
Findings usually involve two or more organ systems, commonly the skin, respiratory tract, gastrointestinal tract, or cardiovascular system. Airway compromise or hypotension may not be present initially but can develop rapidly.
Essential Clinical Assessment
Anaphylaxis is diagnosed on clinical grounds, and early recognition is critical. Ancillary testing should not delay treatment. ECG monitoring is advised in patients with cardiac history, ischemic symptoms, or advanced age.
Diagnostic Evaluation
Laboratory studies are generally not useful in the acute setting. Serum tryptase levels may aid retrospective confirmation. Chest radiography may show hyperinflation in cases with bronchospasm.
Alternative Diagnoses To Consider
Conditions that may mimic anaphylaxis include pulmonary embolism, acute coronary syndromes, asthma, airway obstruction, vasovagal syncope, hereditary angioedema, systemic mastocytosis, hypoglycemia, carcinoid syndrome, and foreign body aspiration.
Prehospital Care Principles
Early airway assessment, oxygen supplementation, IV access, and continuous monitoring are essential. Intramuscular epinephrine should be administered promptly, even before IV access is obtained. Progressive laryngeal edema may necessitate early airway intervention.
Immediate Stabilization Measures
Airway protection and adequate ventilation take priority. Orotracheal intubation is preferred when airway compromise is anticipated. Advanced airway techniques may be required in the presence of significant edema. Epinephrine may be administered via IM, IV, or endotracheal routes, along with aggressive fluid resuscitation.
Emergency Department Management
Continuous cardiac and vital-sign monitoring is required. Persistent bronchospasm is treated with inhaled β2-agonists. Hypotension is addressed with IV fluids and vasopressors if needed. Antihistamines reduce histamine-mediated effects, corticosteroids help prevent biphasic reactions, and glucagon is indicated for epinephrine-resistant anaphylaxis in patients taking β-blockers.
Pharmacologic Therapy
First-line therapy includes intramuscular epinephrine, H1 antihistamines, corticosteroids, and inhaled bronchodilators. Second-line agents include racemic epinephrine, H2 blockers, and glucagon when indicated. Special caution is required in patients receiving β-blockers.
Disposition Planning
Patients requiring intubation or ongoing respiratory or hemodynamic support should be admitted to an intensive care setting. Those with persistent or severe reactions warrant inpatient observation due to the risk of biphasic reactions. Patients with complete symptom resolution may be discharged after a period of observation.
Post-Discharge Follow-Up
All patients should receive early outpatient follow-up, ideally with an allergist. Education regarding trigger avoidance and prescription of self-injectable epinephrine are essential. Patients should be instructed on proper auto-injector use and advised to carry it at all times.
Clinical Pearls And Pitfalls
Delayed recognition of anaphylaxis can result in rapid airway compromise and cardiovascular collapse. Early administration of epinephrine is the single most critical intervention. Patients with a prior history of anaphylaxis require education on avoidance strategies and prompt self-treatment to prevent fatal outcomes.
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Emergency And Acute Medicine – Anemia
Core Definition
Anemia refers to a reduction below normal in total red blood cell (RBC) mass. It is most commonly identified by decreased hemoglobin concentration, hematocrit, or RBC count. Normal reference values vary with age, sex, altitude, and physiologic state. Because hemoglobin and hematocrit reflect concentrations, values may fall due to reduced RBC mass or increased plasma volume. Importantly, anemia is never a normal variant and always signifies an underlying disorder or deficiency that requires evaluation.
Causative Mechanisms
The most common cause of anemia is excessive blood loss, including trauma, gastrointestinal hemorrhage, and menstruation. Increased RBC destruction (hemolysis) may occur due to hypersplenism, autoimmune processes, mechanical injury, toxins, infections, or inherited membrane and enzyme defects. Reduced RBC production results from impaired bone marrow function or deficiencies and is commonly classified by RBC size into microcytic, macrocytic, or normocytic patterns.
Clinical Presentation
Symptoms depend on the severity, chronicity, and speed of onset. Acute anemia may produce hypovolemia, whereas chronic mild anemia may be asymptomatic. Common complaints include fatigue, reduced exercise tolerance, dyspnea on exertion, chest pain, syncope, and signs of bleeding. Physical findings may include pallor, tachycardia, murmurs, orthostatic hypotension, jaundice, splenomegaly, neurologic deficits, or nail and skin changes that reflect the underlying cause.
Initial Evaluation
A focused history should assess bleeding, chronic disease, nutritional status, medication use, and family history. Vital signs and orthostatic measurements are essential. The primary goals are to determine whether anemia is due to blood loss, hemolysis, or impaired RBC production and to assess hemodynamic stability.
Laboratory Assessment
Initial testing includes a complete blood count with RBC indices, reticulocyte count, and peripheral smear. Reticulocyte response helps distinguish between underproduction and increased destruction or loss. Additional studies may include iron studies, vitamin B12 and folate levels, renal function tests, hemolysis markers, stool occult blood testing, and specialized assays such as hemoglobin electrophoresis when indicated.
Diagnostic Considerations
Patterns of anemia guide further evaluation. Microcytic anemia suggests iron deficiency or thalassemia; macrocytic anemia raises concern for vitamin deficiencies, liver disease, or marrow disorders; normocytic anemia may indicate acute blood loss, chronic disease, renal failure, or marrow suppression. Bone marrow biopsy is reserved for selected cases involving suspected marrow pathology.
Differential Diagnoses
Important considerations include acute blood loss, anemia of chronic disease, hemolysis, malignancy, nutritional deficiencies, bone marrow failure, and dilutional anemia. Age-specific factors apply in pediatric, pregnant, and elderly populations.
Emergency Management
Immediate treatment is dictated by severity and stability. Patients with ongoing hemorrhage or hemodynamic compromise require airway support, oxygen, IV access, crystalloid resuscitation, and transfusion when indicated. Most chronic anemias identified in the emergency department do not require urgent intervention.
Definitive Therapy
Management targets the underlying cause. Iron supplementation is used for iron deficiency, erythropoietin for renal failure–associated anemia, corticosteroids or immunosuppression for autoimmune hemolysis, vitamin replacement for nutritional deficiencies, and disease-specific therapies for hematologic malignancies or hemoglobinopathies.
Disposition And Follow-Up
Admission is required for unstable patients, those with symptomatic or severe anemia, ongoing blood loss, or need for transfusion. Stable patients may be discharged with clear outpatient follow-up for diagnostic evaluation and treatment. Newly diagnosed anemia always warrants further investigation.
Clinical Insights And Common Errors
Anemia is a sign, not a diagnosis, and its cause must be identified. Life-threatening cases require rapid correction, while most emergency department presentations represent chronic disease. Failure to recognize occult bleeding or hemolysis and assuming anemia is benign are frequent pitfalls.
Core Definition
Anemia refers to a reduction below normal in total red blood cell (RBC) mass. It is most commonly identified by decreased hemoglobin concentration, hematocrit, or RBC count. Normal reference values vary with age, sex, altitude, and physiologic state. Because hemoglobin and hematocrit reflect concentrations, values may fall due to reduced RBC mass or increased plasma volume. Importantly, anemia is never a normal variant and always signifies an underlying disorder or deficiency that requires evaluation.
Causative Mechanisms
The most common cause of anemia is excessive blood loss, including trauma, gastrointestinal hemorrhage, and menstruation. Increased RBC destruction (hemolysis) may occur due to hypersplenism, autoimmune processes, mechanical injury, toxins, infections, or inherited membrane and enzyme defects. Reduced RBC production results from impaired bone marrow function or deficiencies and is commonly classified by RBC size into microcytic, macrocytic, or normocytic patterns.
Clinical Presentation
Symptoms depend on the severity, chronicity, and speed of onset. Acute anemia may produce hypovolemia, whereas chronic mild anemia may be asymptomatic. Common complaints include fatigue, reduced exercise tolerance, dyspnea on exertion, chest pain, syncope, and signs of bleeding. Physical findings may include pallor, tachycardia, murmurs, orthostatic hypotension, jaundice, splenomegaly, neurologic deficits, or nail and skin changes that reflect the underlying cause.
Initial Evaluation
A focused history should assess bleeding, chronic disease, nutritional status, medication use, and family history. Vital signs and orthostatic measurements are essential. The primary goals are to determine whether anemia is due to blood loss, hemolysis, or impaired RBC production and to assess hemodynamic stability.
Laboratory Assessment
Initial testing includes a complete blood count with RBC indices, reticulocyte count, and peripheral smear. Reticulocyte response helps distinguish between underproduction and increased destruction or loss. Additional studies may include iron studies, vitamin B12 and folate levels, renal function tests, hemolysis markers, stool occult blood testing, and specialized assays such as hemoglobin electrophoresis when indicated.
Diagnostic Considerations
Patterns of anemia guide further evaluation. Microcytic anemia suggests iron deficiency or thalassemia; macrocytic anemia raises concern for vitamin deficiencies, liver disease, or marrow disorders; normocytic anemia may indicate acute blood loss, chronic disease, renal failure, or marrow suppression. Bone marrow biopsy is reserved for selected cases involving suspected marrow pathology.
Differential Diagnoses
Important considerations include acute blood loss, anemia of chronic disease, hemolysis, malignancy, nutritional deficiencies, bone marrow failure, and dilutional anemia. Age-specific factors apply in pediatric, pregnant, and elderly populations.
Emergency Management
Immediate treatment is dictated by severity and stability. Patients with ongoing hemorrhage or hemodynamic compromise require airway support, oxygen, IV access, crystalloid resuscitation, and transfusion when indicated. Most chronic anemias identified in the emergency department do not require urgent intervention.
Definitive Therapy
Management targets the underlying cause. Iron supplementation is used for iron deficiency, erythropoietin for renal failure–associated anemia, corticosteroids or immunosuppression for autoimmune hemolysis, vitamin replacement for nutritional deficiencies, and disease-specific therapies for hematologic malignancies or hemoglobinopathies.
Disposition And Follow-Up
Admission is required for unstable patients, those with symptomatic or severe anemia, ongoing blood loss, or need for transfusion. Stable patients may be discharged with clear outpatient follow-up for diagnostic evaluation and treatment. Newly diagnosed anemia always warrants further investigation.
Clinical Insights And Common Errors
Anemia is a sign, not a diagnosis, and its cause must be identified. Life-threatening cases require rapid correction, while most emergency department presentations represent chronic disease. Failure to recognize occult bleeding or hemolysis and assuming anemia is benign are frequent pitfalls.
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Emergency And Acute Medicine – Amphetamine Poisoning
Core Overview
Amphetamine toxicity results from increased release of norepinephrine, dopamine, and serotonin, reduced catecholamine reuptake, and direct stimulation of α- and β-adrenergic receptors. These effects lead to a classic sympathomimetic toxidrome that can range from mild agitation to life-threatening hyperthermia, cardiovascular collapse, and multiorgan failure.
Underlying Causes
Amphetamine poisoning may occur from prescription stimulants such as amphetamine, dextroamphetamine, methamphetamine, methylphenidate, phentermine, and related agents. Illicit or “designer” drugs include methamphetamine (“crystal,” “ice,” “crank”), MDMA (“ecstasy”), MDA, methcathinone, and mephedrone, sometimes sold as “bath salts.” These substances are often synthesized in clandestine laboratories and may be smoked, injected, or insufflated, leading to rapid onset and prolonged toxicity.
Clinical Features
Central nervous system findings include agitation, delirium, hyperactivity, tremors, mydriasis, headache, hyperreflexia, seizures, status epilepticus, and coma. Psychiatric manifestations include euphoria, anxiety, aggression, hallucinations, and compulsive behaviors. Cardiovascular effects include tachycardia, hypertensive crisis, dysrhythmias, and potential cardiovascular collapse. Systemic complications include hyperthermia, diaphoresis, rhabdomyolysis, myoglobinuria, acute renal failure, disseminated intravascular coagulation, and anorexia.
History And Physical Examination
History should establish the substance used, dose, timing, route of exposure, and possible coingestions. Symptoms suggesting end-organ injury such as chest pain, dyspnea, headache, confusion, or vomiting should be sought. Physical examination commonly reveals agitation, tachycardia, diaphoresis, and mydriasis. Severe intoxication may present with hyperthermia, hypertensive crisis, seizures, hypotension, or respiratory distress. Careful evaluation for trauma, infection, focal neurologic deficits, cardiac murmurs, pneumothorax, and soft-tissue infections is essential.
Essential Emergency Evaluation
Vital signs must be closely monitored, with core temperature measurement required if hyperthermia is suspected. A temperature greater than 40°C is an ominous sign and mandates immediate intervention. Continuous cardiac monitoring and ECG assessment are essential to detect ischemia or dysrhythmias.
Diagnostic Testing
Laboratory evaluation includes electrolytes, glucose, BUN, creatinine, creatine phosphokinase, urinalysis for blood and myoglobin, and coagulation studies if DIC is suspected. Hyperkalemia and acidosis may accompany rhabdomyolysis and renal failure. Urine toxicology screening may identify coingestants, although some synthetic stimulants may not be detected. Aspirin and acetaminophen levels should be obtained if intentional overdose is possible. Imaging includes chest radiography for pulmonary edema or ARDS and head CT for altered mental status, focal deficits, or severe headache.
Conditions To Differentiate
Important alternative diagnoses include sepsis, thyroid storm, serotonin syndrome, neuroleptic malignant syndrome, pheochromocytoma, subarachnoid hemorrhage, cocaine toxicity, ethanol or sedative withdrawal, anticholinergic toxicity, and other causes of seizures or hypertensive emergencies.
Emergency Department Management
Prehospital care focuses on safety, IV access, and prevention of self-injury. Initial stabilization prioritizes airway, breathing, and circulation, IV fluid resuscitation, cardiac monitoring, and administration of naloxone, glucose, and thiamine if mental status is altered. Activated charcoal may be used early, and whole-bowel irrigation is indicated for body packers. Benzodiazepines are first-line therapy for agitation, seizures, and hypertension related to catecholamine excess. Severe hypertension may require α-blockade with phentolamine or vasodilators such as nitroprusside; β-blockers should be avoided. Hyperthermia requires aggressive sedation, active cooling, and paralysis with nondepolarizing agents if necessary. Rhabdomyolysis is treated with IV fluids to maintain adequate urine output, and dialysis is considered for renal failure or refractory hyperkalemia.
Disposition And Follow-Up
Admission is required for patients with hyperthermia, persistent altered mental status, hypertensive crisis, seizures, rhabdomyolysis, or ongoing tachycardia. Asymptomatic patients who remain stable after observation may be discharged. Referral for substance use treatment, detoxification, and rehabilitation should be arranged when appropriate.
Key Clinical Lessons And Common Errors
Severe amphetamine toxicity carries high morbidity and mortality if hyperthermia and agitation are not rapidly controlled. Core temperature monitoring is critical, and aggressive sedation with benzodiazepines plus active cooling is lifesaving. Rhabdomyolysis and hyperkalemia must be anticipated and treated early. Physical restraints should be minimized when possible, as they may worsen hyperthermia and acidosis. Benzodiazepines remain the cornerstone of treatment for symptomatic methamphetamine and amphetamine intoxication.
Core Overview
Amphetamine toxicity results from increased release of norepinephrine, dopamine, and serotonin, reduced catecholamine reuptake, and direct stimulation of α- and β-adrenergic receptors. These effects lead to a classic sympathomimetic toxidrome that can range from mild agitation to life-threatening hyperthermia, cardiovascular collapse, and multiorgan failure.
Underlying Causes
Amphetamine poisoning may occur from prescription stimulants such as amphetamine, dextroamphetamine, methamphetamine, methylphenidate, phentermine, and related agents. Illicit or “designer” drugs include methamphetamine (“crystal,” “ice,” “crank”), MDMA (“ecstasy”), MDA, methcathinone, and mephedrone, sometimes sold as “bath salts.” These substances are often synthesized in clandestine laboratories and may be smoked, injected, or insufflated, leading to rapid onset and prolonged toxicity.
Clinical Features
Central nervous system findings include agitation, delirium, hyperactivity, tremors, mydriasis, headache, hyperreflexia, seizures, status epilepticus, and coma. Psychiatric manifestations include euphoria, anxiety, aggression, hallucinations, and compulsive behaviors. Cardiovascular effects include tachycardia, hypertensive crisis, dysrhythmias, and potential cardiovascular collapse. Systemic complications include hyperthermia, diaphoresis, rhabdomyolysis, myoglobinuria, acute renal failure, disseminated intravascular coagulation, and anorexia.
History And Physical Examination
History should establish the substance used, dose, timing, route of exposure, and possible coingestions. Symptoms suggesting end-organ injury such as chest pain, dyspnea, headache, confusion, or vomiting should be sought. Physical examination commonly reveals agitation, tachycardia, diaphoresis, and mydriasis. Severe intoxication may present with hyperthermia, hypertensive crisis, seizures, hypotension, or respiratory distress. Careful evaluation for trauma, infection, focal neurologic deficits, cardiac murmurs, pneumothorax, and soft-tissue infections is essential.
Essential Emergency Evaluation
Vital signs must be closely monitored, with core temperature measurement required if hyperthermia is suspected. A temperature greater than 40°C is an ominous sign and mandates immediate intervention. Continuous cardiac monitoring and ECG assessment are essential to detect ischemia or dysrhythmias.
Diagnostic Testing
Laboratory evaluation includes electrolytes, glucose, BUN, creatinine, creatine phosphokinase, urinalysis for blood and myoglobin, and coagulation studies if DIC is suspected. Hyperkalemia and acidosis may accompany rhabdomyolysis and renal failure. Urine toxicology screening may identify coingestants, although some synthetic stimulants may not be detected. Aspirin and acetaminophen levels should be obtained if intentional overdose is possible. Imaging includes chest radiography for pulmonary edema or ARDS and head CT for altered mental status, focal deficits, or severe headache.
Conditions To Differentiate
Important alternative diagnoses include sepsis, thyroid storm, serotonin syndrome, neuroleptic malignant syndrome, pheochromocytoma, subarachnoid hemorrhage, cocaine toxicity, ethanol or sedative withdrawal, anticholinergic toxicity, and other causes of seizures or hypertensive emergencies.
Emergency Department Management
Prehospital care focuses on safety, IV access, and prevention of self-injury. Initial stabilization prioritizes airway, breathing, and circulation, IV fluid resuscitation, cardiac monitoring, and administration of naloxone, glucose, and thiamine if mental status is altered. Activated charcoal may be used early, and whole-bowel irrigation is indicated for body packers. Benzodiazepines are first-line therapy for agitation, seizures, and hypertension related to catecholamine excess. Severe hypertension may require α-blockade with phentolamine or vasodilators such as nitroprusside; β-blockers should be avoided. Hyperthermia requires aggressive sedation, active cooling, and paralysis with nondepolarizing agents if necessary. Rhabdomyolysis is treated with IV fluids to maintain adequate urine output, and dialysis is considered for renal failure or refractory hyperkalemia.
Disposition And Follow-Up
Admission is required for patients with hyperthermia, persistent altered mental status, hypertensive crisis, seizures, rhabdomyolysis, or ongoing tachycardia. Asymptomatic patients who remain stable after observation may be discharged. Referral for substance use treatment, detoxification, and rehabilitation should be arranged when appropriate.
Key Clinical Lessons And Common Errors
Severe amphetamine toxicity carries high morbidity and mortality if hyperthermia and agitation are not rapidly controlled. Core temperature monitoring is critical, and aggressive sedation with benzodiazepines plus active cooling is lifesaving. Rhabdomyolysis and hyperkalemia must be anticipated and treated early. Physical restraints should be minimized when possible, as they may worsen hyperthermia and acidosis. Benzodiazepines remain the cornerstone of treatment for symptomatic methamphetamine and amphetamine intoxication.
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Emergency And Acute Medicine – Amenorrhea
Core Overview
Amenorrhea refers to the absence of menstruation. Primary amenorrhea is defined as the absence of spontaneous uterine bleeding by age 16 years or within 5 years of breast development, which normally begins by age 13. Secondary amenorrhea is the absence of uterine bleeding for 3 months in a woman with previously regular menses or for 9 months in a woman with prior oligomenorrhea. Secondary amenorrhea is more common, and pregnancy is the most frequent cause encountered in emergency care.
Underlying Causes
Primary amenorrhea is most commonly due to gonadal failure, hypothalamic–pituitary disorders, chromosomal abnormalities, structural abnormalities such as imperforate hymen, or conditions such as Turner syndrome. Secondary amenorrhea is frequently related to pregnancy, lactation, or the postpartum state. Other causes include Asherman syndrome, dysfunction of the hypothalamic–pituitary–ovarian axis, polycystic ovarian syndrome, endocrinopathies, extremes of body weight, intense physical exercise, medications, autoimmune disease, ovarian failure, and menopause.
Clinical Features
History should focus on age at menarche, menstrual pattern, sexual activity, exercise habits, weight change, chronic illness, medication use, prior chemotherapy or CNS radiation, family history, and infertility. Physical examination may reveal signs of low estrogen such as atrophic vaginal mucosa and mood changes, or signs of hyperandrogenism including truncal obesity, hirsutism, acne, and male-pattern baldness. Thyroid examination, pelvic or genital examination, and Tanner staging are essential components of assessment.
Essential Emergency Evaluation
A pregnancy test is mandatory in all patients presenting with amenorrhea. If pregnancy testing is negative and the patient is otherwise stable, no additional emergent testing is typically required in the emergency department.
Diagnostic Testing
If pregnancy is excluded, further laboratory evaluation such as TSH, prolactin, LH, and FSH can be deferred to outpatient follow-up with gynecology or primary care. Imaging is not required emergently unless there is concern for ectopic pregnancy or another acute process based on the patient’s presentation. No diagnostic procedures are typically required in the emergency setting.
Conditions To Differentiate
Pregnancy must always be excluded first, including ectopic pregnancy when clinically suspected.
Emergency Department Management
Prehospital care is supportive. If amenorrhea is related to pregnancy, management should follow pregnancy-specific protocols. In the emergency department, treatment consists primarily of reassurance, patient education, and appropriate referral for outpatient evaluation.
Disposition And Follow-Up
Admission is not required unless there is concern for ectopic pregnancy or another emergent condition. Most patients can be safely discharged with referral to gynecology. Follow-up with a gynecologist is recommended for definitive evaluation and management.
Key Clinical Lessons And Common Errors
Pregnancy is the most important and common cause of amenorrhea in the emergency department and must always be ruled out. Urine pregnancy testing may yield false-negative results in dilute urine or early pregnancy, and serum testing should be considered when clinical suspicion is high, particularly for ectopic pregnancy. Eating disorders such as anorexia nervosa should be considered, especially in adolescents presenting with amenorrhea.
Core Overview
Amenorrhea refers to the absence of menstruation. Primary amenorrhea is defined as the absence of spontaneous uterine bleeding by age 16 years or within 5 years of breast development, which normally begins by age 13. Secondary amenorrhea is the absence of uterine bleeding for 3 months in a woman with previously regular menses or for 9 months in a woman with prior oligomenorrhea. Secondary amenorrhea is more common, and pregnancy is the most frequent cause encountered in emergency care.
Underlying Causes
Primary amenorrhea is most commonly due to gonadal failure, hypothalamic–pituitary disorders, chromosomal abnormalities, structural abnormalities such as imperforate hymen, or conditions such as Turner syndrome. Secondary amenorrhea is frequently related to pregnancy, lactation, or the postpartum state. Other causes include Asherman syndrome, dysfunction of the hypothalamic–pituitary–ovarian axis, polycystic ovarian syndrome, endocrinopathies, extremes of body weight, intense physical exercise, medications, autoimmune disease, ovarian failure, and menopause.
Clinical Features
History should focus on age at menarche, menstrual pattern, sexual activity, exercise habits, weight change, chronic illness, medication use, prior chemotherapy or CNS radiation, family history, and infertility. Physical examination may reveal signs of low estrogen such as atrophic vaginal mucosa and mood changes, or signs of hyperandrogenism including truncal obesity, hirsutism, acne, and male-pattern baldness. Thyroid examination, pelvic or genital examination, and Tanner staging are essential components of assessment.
Essential Emergency Evaluation
A pregnancy test is mandatory in all patients presenting with amenorrhea. If pregnancy testing is negative and the patient is otherwise stable, no additional emergent testing is typically required in the emergency department.
Diagnostic Testing
If pregnancy is excluded, further laboratory evaluation such as TSH, prolactin, LH, and FSH can be deferred to outpatient follow-up with gynecology or primary care. Imaging is not required emergently unless there is concern for ectopic pregnancy or another acute process based on the patient’s presentation. No diagnostic procedures are typically required in the emergency setting.
Conditions To Differentiate
Pregnancy must always be excluded first, including ectopic pregnancy when clinically suspected.
Emergency Department Management
Prehospital care is supportive. If amenorrhea is related to pregnancy, management should follow pregnancy-specific protocols. In the emergency department, treatment consists primarily of reassurance, patient education, and appropriate referral for outpatient evaluation.
Disposition And Follow-Up
Admission is not required unless there is concern for ectopic pregnancy or another emergent condition. Most patients can be safely discharged with referral to gynecology. Follow-up with a gynecologist is recommended for definitive evaluation and management.
Key Clinical Lessons And Common Errors
Pregnancy is the most important and common cause of amenorrhea in the emergency department and must always be ruled out. Urine pregnancy testing may yield false-negative results in dilute urine or early pregnancy, and serum testing should be considered when clinical suspicion is high, particularly for ectopic pregnancy. Eating disorders such as anorexia nervosa should be considered, especially in adolescents presenting with amenorrhea.
