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Emergency And Acute Medicine – Poisoning, Antidotes
Antidote therapy is used in specific toxicologic emergencies and should be administered in conjunction with supportive care and consultation with a poison control center or medical toxicologist when appropriate.
N-acetylcysteine (NAC) is indicated for acetaminophen overdose. It is most effective when given within the first 8 hours after ingestion. Common adverse effects include unpleasant odor, nausea, and vomiting. Oral dosing consists of 140 mg/kg followed by 70 mg/kg every 4 hours for 17 doses. Intravenous dosing includes 150 mg/kg in 200 mL D5W over 60 minutes, then 50 mg/kg in 500 mL D5W over 4 hours, followed by 100 mg/kg in 1,000 mL D5W over 16 hours. In pediatric patients, IV fluid volumes must be reduced to avoid fluid overload and hyponatremia.
Atropine is used for bradycardia due to drugs and for organophosphate insecticide poisoning. Caution is advised in myasthenia gravis, narrow-angle glaucoma, hypertension, coronary ischemia, and urinary obstruction. Adult dose is 1–2 mg IV. Pediatric dose is 0.02 mg/kg IV (minimum 0.1 mg). Large repeated doses may be required in organophosphate poisoning.
Benztropine (Cogentin) is indicated for acute dystonic reactions. It should be used cautiously in carbamate exposure, myasthenia gravis, narrow-angle glaucoma, hypertension, coronary ischemia, and urinary obstruction. Adult dosing is 1–2 mg IV for acute reactions or orally for prevention. Pediatric dose is 0.02 mg/kg IV or PO.
Benzodiazepines are indicated for agitation, stimulant toxicity, and seizures. Respiratory and CNS depression are potential adverse effects. Midazolam dosing is 1 mg IV or IM every 2–3 minutes as needed in adults, and 0.1 mg/kg IV or IM in children. Diazepam dosing is 2–5 mg IV or IM in adults (repeat in 10–15 minutes) and 0.1 mg/kg IV or IM in pediatrics.
Sodium bicarbonate is used for tricyclic antidepressant poisoning, metabolic acidosis, and urinary alkalinization. Adverse effects include congestive heart failure, excessive alkalosis, and hypokalemia. For serum alkalinization, give 1 mEq/kg IV push. For urine alkalinization, administer 100–150 mEq in 1 L D5W at 2–3 mL/kg/hour IV with a urine pH goal of 7–8.
Black widow spider antivenin (Latrodectus mactans) is indicated for severe hypertension and muscle spasms not relieved by analgesics and muscle relaxants, and may be considered in young children, elderly patients, and pregnant women with threatened abortion. It is equine-derived and may cause immediate hypersensitivity or delayed serum sickness. Dose is 1–2 vials IM or slow IV over 15–30 minutes; dilute one vial in 50 mL saline for IV use.
Botulinum antitoxin (trivalent A, B, E) is indicated in clinical botulism before onset of paralysis. It binds only free toxin and is not used for infant botulism. It is equine-derived with risk of hypersensitivity. Administer 1–2 vials IV every 4 hours for 4–5 doses after reconstitution.
Calcium is indicated for hyperkalemia with cardiac toxicity, hydrofluoric acid burns, calcium channel blocker overdose, and citrate, oxalate, or phosphate poisoning. Avoid in digoxin toxicity and hypercalcemia. Adult dose is 5–10 mL of 10% calcium chloride or 10–20 mL of 10% calcium gluconate IV. Pediatric dose is 0.1–0.2 mL/kg of 10% calcium chloride or 0.2–0.3 mL/kg of 10% calcium gluconate IV.
Calcium EDTA is used for lead and certain heavy metal toxicities. It may cause nephrotoxicity and other adverse effects. Dose is 1 g/m²/day IV over 8–12 hours for 5 days, with repeat cycles guided by blood lead levels.
Cyanide poisoning can be treated with a cyanide antidote kit or hydroxocobalamin. The cyanide kit includes amyl nitrite (inhaled until IV access is established), sodium nitrite (300 mg IV in adults; 0.3 mL/kg of 3% solution in children), and sodium thiosulfate (12.5 g IV in adults; 50 mg/kg in children). Hydroxocobalamin is given as 5 g IV over 15 minutes in adults, repeatable once; suggested pediatric dose is 70 mg/kg IV.
Dantrolene is indicated for malignant hyperthermia, neuroleptic malignant syndrome, serotonin syndrome, and severe muscle rigidity. Dose is 1–2 mg/kg IV bolus, repeated every 10–15 minutes as needed, maximum 10 mg/kg.
Deferoxamine treats iron toxicity. It should not be used for more than 24 hours due to risk of delayed ARDS. Dose is 10–15 mg/kg/hour IV, increased in severe cases.
Digoxin-specific antibody fragments (Digibind) are used in digoxin or digitoxin toxicity. One vial (40 mg) binds 0.6 mg digoxin. Dose estimation is based on serum level and patient weight, with typical dosing of 10–20 vials in acute overdose and 4–6 vials in chronic toxicity.
Dimercaprol (BAL) is indicated for arsenic, gold, mercury, and severe lead toxicity with encephalopathy. Dose is 3 mg/kg IM every 4 hours for 2 days, then every 12 hours for 7 days.
Flumazenil reverses benzodiazepine effects but is contraindicated in tricyclic antidepressant overdose and may precipitate seizures or withdrawal. Adult dose is 0.2 mg IV slow push, repeated every 2–3 minutes up to 1 mg. Pediatric dose is 0.01–0.05 mg/kg IV.
Fomepizole is used for methanol and ethylene glycol toxicity. Dose is 15 mg/kg IV loading, then 10 mg/kg every 12 hours for four doses, then 15 mg/kg every 12 hours thereafter.
Glucagon is used for β-blocker or calcium channel blocker overdose with bradycardia or hypotension. Adult dose is 5–10 mg IV over 1 minute; pediatric dose is 0.15 mg/kg IV.
High-dose insulin with glucose is used in severe calcium channel blocker overdose or hyperkalemia refractory to other therapy. Close glucose monitoring is required.
Naloxone (Narcan) reverses opioid toxicity. Adult dose is 0.4–2 mg IV or IM, repeat up to 10 mg. Pediatric dose is 0.1 mg/kg IV or IM. Acute withdrawal and agitation may occur.
Octreotide treats sulfonylurea-induced hypoglycemia. Adult dose is 50 micrograms subcutaneously every 6 hours. Pediatric dose is 4–5 micrograms/kg/day divided every 6 hours.
Pralidoxime (2-PAM) is used in organophosphate toxicity in conjunction with atropine. Adult dose is 1–2 g IV over 15 minutes, repeat as needed. Pediatric dose is 25–50 mg/kg over 15 minutes.
Protamine reverses heparin anticoagulation. Dose is 1 mg per 100 IU of heparin administered, given slowly IV.
Pyridoxine (vitamin B6) is used for isoniazid-induced seizures. If ingestion amount is unknown, give 5 g IV in adults or 1 g in children.
Vitamin K (phytonadione) reverses warfarin anticoagulation. Dose ranges from 2–10 mg PO or slow IV, repeat as needed based on INR.
Hyperbaric oxygen is indicated for severe carbon monoxide poisoning.
Many antivenins, including those for coral snake and rattlesnake envenomation, are animal-derived and carry risk of hypersensitivity and serum sickness. Premedication and close monitoring are required.
Antidote therapy should always accompany appropriate supportive care, monitoring, and consultation with poison control.
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Emergency And Acute Medicine – Poisoning
Poisoning may be intentional or unintentional. Any patient presenting with an unexplained change in mental status should be evaluated for possible intoxication or overdose. Intentional poisoning may be related to depression, suicide attempts, homicide, or recreational drug abuse. Unintentional poisoning commonly occurs in children and may result from accidental ingestion, therapeutic errors such as double dosing, or recreational experimentation. In pediatric patients, most accidental ingestions occur in children aged 1–5 years. A history that is inconsistent or suspicious should raise concern for possible child abuse.
Clinical presentation varies depending on the substance involved. Neurologic findings may include lethargy, agitation, coma, hallucinations, or seizures. Respiratory effects may range from tachypnea to bradypnea or apnea, with possible inability to protect the airway. Cardiovascular manifestations include dysrhythmias and conduction abnormalities. Vital sign abnormalities may include hyperthermia or hypothermia, tachycardia or bradycardia, and hypertension or hypotension.
Recognition of toxidromes can guide management. Anticholinergic toxicity presents with altered mental status, dry skin and mucous membranes, fixed dilated pupils, tachycardia, hyperthermia, flushing, and urinary retention. Cholinergic toxicity presents with excessive secretions including salivation, lacrimation, urination, diaphoresis, miosis, bronchospasm, and wheezing. Opiate toxicity is characterized by central nervous system and respiratory depression with miosis. Sympathomimetic toxicity presents with CNS excitation, seizures, tachycardia, hypertension, and diaphoresis.
Initial evaluation requires complete vital signs including core temperature and a thorough physical examination, paying attention to pupils, skin findings, and unusual odors. Laboratory testing typically includes electrolytes, BUN, creatinine, and glucose. Calculation of the anion gap (normal 8–12) is essential when metabolic acidosis is suspected. Elevated anion gap metabolic acidosis can be remembered using the mnemonic “A CAT MUD PILES,” which includes causes such as alcoholic ketoacidosis, cyanide, carbon monoxide, salicylates, methanol, uremia, diabetic ketoacidosis, iron, lactic acidosis, and ethylene glycol. Serum osmol gap should be calculated when toxic alcohol ingestion is suspected. The calculated osmolality is 2(Na⁺) + glucose/18 + BUN/2.8 + ethanol/4.6 (if ethanol in mg/dL). An osmol gap greater than 10 suggests substances remembered by the mnemonic “ME DIE A”: methanol, ethanol, diuretics (mannitol, glycerin, sorbitol), isopropyl alcohol, ethylene glycol, and acetone. A normal osmol gap does not completely exclude toxic alcohol ingestion. Additional testing may include pregnancy testing, acetaminophen level in suicidal ingestions, toxicology screening, ECG for conduction abnormalities or QRS/QT prolongation, head CT for unexplained altered mental status, and chest radiograph if aspiration is suspected.
The differential diagnosis for altered mental status includes intracranial mass or hemorrhage, infection or sepsis, endocrine abnormalities, hypothermia, hypoxia, metabolic disturbances, and psychogenic causes. These must always be considered alongside toxicologic causes.
Pre-hospital management includes searching the scene for clues such as pill bottles or drug paraphernalia and transporting all medications for identification. Uncooperative patients may require restraint for safety. Comorbid trauma, medical illness, or environmental exposures should be considered. Activated charcoal may be administered pre-hospital in selected cases if transport time is prolonged.
Initial stabilization in the emergency department follows standard ABC principles. Endotracheal intubation is performed as needed for airway protection, oxygenation, and ventilation. Supplemental oxygen, pulse oximetry, cardiac monitoring, and IV access are established. Hypotension is treated with intravenous 0.9% normal saline boluses and vasopressors if persistent. Bradycardia may require atropine or pacing. In patients with altered mental status, administration of thiamine, dextrose (after checking glucose), and naloxone is appropriate.
Decontamination strategies depend on the timing and substance ingested. Orogastric lavage may be considered within one hour of potentially lethal ingestion without a known antidote, provided the airway is protected. Activated charcoal is most effective within a few hours of ingestion and is contraindicated in caustic ingestions, unprotected airways, or bowel obstruction. Charcoal does not effectively bind metals (iron, lithium), alcohols, or potassium. Whole-bowel irrigation with polyethylene glycol solution may be used for sustained-release preparations, iron or lithium ingestion, and body packers, but is contraindicated in bowel obstruction, perforation, or hypotension.
Enhanced elimination techniques include multiple-dose activated charcoal for drugs such as theophylline, carbamazepine, and phenobarbital. Urinary alkalinization is used for salicylates and phenobarbital. Hemodialysis is indicated for lithium, salicylates, theophylline, toxic alcohols, and valproate in selected cases. Seizures are treated initially with benzodiazepines such as diazepam or lorazepam. Persistent seizures may require phenobarbital. Phenytoin is generally not effective for toxicologic seizures unless related to epilepsy or status epilepticus of other etiology.
Specific antidotes are used when appropriate. Examples include N-acetylcysteine for acetaminophen toxicity, physostigmine for severe anticholinergic toxicity, flumazenil for selected benzodiazepine overdoses, glucagon for β-blocker toxicity, calcium and insulin for calcium-channel blocker overdose, oxygen or hyperbaric oxygen for carbon monoxide, vitamin K for warfarin toxicity, hydroxocobalamin or cyanide antidote kit for cyanide, digoxin-specific antibody fragments for digoxin toxicity, fomepizole or ethanol for methanol and ethylene glycol, deferoxamine for iron, pyridoxine for isoniazid, methylene blue for methemoglobinemia, naloxone for opioid toxicity, atropine and pralidoxime for organophosphates, and sodium bicarbonate for tricyclic antidepressant toxicity.
Admission is required for patients with altered mental status, cardiopulmonary instability, suicidal intent, significant laboratory abnormalities, or risk of delayed decompensation. Discharge may be considered for patients who are psychiatrically cleared, detoxified, hemodynamically stable, and medically safe. Accidental poisonings require prevention counseling, while intentional poisonings require psychiatric evaluation. Substance abuse referral should be considered when appropriate. In pregnancy, treatment of the mother is generally the best treatment for the fetus.
Clinicians must avoid overlooking non-toxicologic causes of altered mental status and should not rely solely on urine drug screens, as these test for a limited number of substances and may produce false-positive or false-negative results.
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Emergency And Acute Medicine – Pneumothorax
Pneumothorax is defined as the presence of free air within the intrapleural space. Spontaneous pneumothorax occurs due to atraumatic rupture of an alveolus, bronchiole, or subpleural bleb. Primary spontaneous pneumothorax accounts for approximately two-thirds of cases and occurs in patients without known underlying lung disease, typically young, tall, thin individuals aged 20–40 years. Risk factors include smoking, family history, Marfan syndrome, homocystinuria, and thoracic endometriosis. Secondary spontaneous pneumothorax occurs in the presence of underlying pulmonary pathology. Tension pneumothorax is a life-threatening form in which air enters the pleural space and becomes trapped through a “ball-valve” mechanism, leading to increased intrapleural pressure, decreased venous return, reduced cardiac output, mediastinal shift, ventilation–perfusion mismatch, and hypoxemia.
Secondary pneumothorax may result from airway diseases such as chronic obstructive pulmonary disease (COPD), asthma, and cystic fibrosis; infections including necrotizing bacterial pneumonia, tuberculosis, fungal pneumonia, and Pneumocystis jirovecii infection; neoplasms; interstitial lung diseases such as sarcoidosis and idiopathic pulmonary fibrosis; lymphangiomyomatosis; tuberous sclerosis; pneumoconioses; connective tissue diseases; pulmonary infarction; endometriosis; blunt or penetrating chest trauma; and iatrogenic causes such as central line placement or other vascular access procedures.
Symptoms typically correlate with the size of the pneumothorax. Patients often present with sudden-onset, sharp, pleuritic chest pain on the affected side and shortness of breath. Some may report a dull ache in delayed presentations. Cough, malaise, or minimal symptoms may occur in small pneumothoraces. On examination, patients may have tachypnea and asymmetric decreased breath sounds with hyperresonance to percussion on the affected side. Simple spontaneous pneumothoraces usually have heart rates under 120 bpm. In tension pneumothorax, findings may include hypotension, tachycardia greater than 120 bpm, diaphoresis, cyanosis, jugular venous distention, tracheal deviation away from the affected side, and cardiovascular collapse.
Imaging is central to diagnosis. However, in hemodynamically unstable patients with strong clinical suspicion of tension pneumothorax, chest decompression must not be delayed for imaging. Upright chest radiography is the standard initial test and demonstrates absence of lung markings beyond a visible visceral pleural line. Additional findings may include mediastinal shift, the deep sulcus sign (particularly in supine trauma patients), inversion of the diaphragm, or displacement of the anterior junction line. Expiratory films do not significantly increase diagnostic yield. Chest CT is highly sensitive for small pneumothoraces but is rarely necessary for routine diagnosis. Point-of-care ultrasound is increasingly used; absence of lung sliding and comet-tail artifacts, along with characteristic M-mode findings, strongly suggests pneumothorax and may be more sensitive than chest radiography in experienced hands. ECG may show nonspecific changes and is often obtained to exclude cardiac causes of chest pain.
Initial stabilization includes cardiac monitoring, pulse oximetry, 100% oxygen via nonrebreather mask, and intravenous access. Unstable patients with suspected tension pneumothorax require immediate needle thoracostomy followed by tube thoracostomy. Needle decompression is performed using a 14–18 gauge angiocatheter in the second intercostal space at the midclavicular line or the fourth or fifth intercostal space at the anterior axillary line. Standard angiocatheters may be too short in larger patients; longer catheters may be required.
Management depends on size and clinical stability. Small primary spontaneous pneumothoraces with less than 15% lung collapse and no respiratory or cardiovascular compromise may be observed with 100% oxygen for 4–6 hours, followed by repeat chest radiography. Simple aspiration using an 8F catheter with a three-way stopcock may be attempted for 15–30% collapse or enlarging small pneumothoraces. Air is aspirated until resistance is met or up to 3 liters have been removed. If imaging confirms resolution, the catheter can be removed and the patient discharged with follow-up. A second aspiration may be attempted if the first fails. A Heimlich valve may be used for persistent but stable pneumothoraces with less than 30% collapse after failed aspiration. Suction at 20 cm H₂O may be applied if necessary.
Tube thoracostomy is indicated for tension pneumothorax, traumatic pneumothorax, pneumothorax in patients requiring positive-pressure ventilation, pneumothorax with greater than 30% collapse, most secondary pneumothoraces, or definitive management after needle decompression. Small-caliber tubes (7–14F) are appropriate for primary spontaneous pneumothorax, whereas larger tubes (20–28F) are used for secondary pneumothorax or when pleural fluid or mechanical ventilation is anticipated. All side holes must remain within the thoracic cavity to prevent air leak. The tube is connected to a water-seal device or Heimlich valve in stable patients without effusion. Complications include intercostal vessel bleeding, tube kinking or clogging, malposition, and re-expansion pulmonary edema, which requires supportive care.
Local anesthesia with 1% lidocaine with epinephrine (maximum 7 mg/kg up to 500 mg) is used for procedures, and procedural sedation may be considered in stable patients. Antibiotics are not indicated for clean procedures.
Admission is required for tension pneumothorax or any patient requiring chest tube placement. Stable patients with small pneumothoraces managed conservatively or with successful aspiration may be discharged with close follow-up at 24 hours and one week, including repeat chest radiographs. Patients must receive clear instructions to return immediately for recurrent chest pain or dyspnea. Persistent failure of lung re-expansion at one week warrants cardiothoracic surgery consultation.
Timely recognition and decompression of tension pneumothorax are critical to prevent rapid hemodynamic compromise. Proper tube placement and awareness of associated injuries, including mediastinal or esophageal pathology when pneumomediastinum is present, are essential to avoid complications.
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Emergency And Acute Medicine – Pneumomediastinum
Pneumomediastinum refers to the presence of free air within the mediastinum. It may arise from the esophagus, lungs, or bronchial tree and can occur spontaneously (primary pneumomediastinum) or secondary to trauma, instrumentation, surgery, infection, or barotrauma. Spontaneous pneumomediastinum results from increased intra-alveolar pressure with subsequent alveolar rupture, allowing air to dissect along bronchovascular sheaths toward the hilum and into the mediastinum. Air may then track into fascial planes of the neck, producing subcutaneous emphysema. This condition is most common in young males and often follows Valsalva maneuvers such as forceful vomiting, coughing, strenuous exercise, labor, or inhalational drug use. Secondary pneumomediastinum may result from thoracic trauma, positive-pressure ventilation, esophageal rupture, or mediastinal infection. Tension pneumomediastinum is rare but life-threatening and may occur in ventilated patients.
Chest pain is the most common presenting symptom and is typically sharp, pleuritic, retrosternal, and sometimes radiates to the back or arms. Dyspnea is common. Patients may report neck pain, throat discomfort, dysphagia, or a sensation of neck swelling due to air tracking into cervical tissues. Subcutaneous emphysema is frequently found in the supraclavicular region and anterior neck. Dysphonia or hoarseness may occur. Hamman crunch, a precordial crunching sound synchronous with the heartbeat and best heard in the left lateral decubitus position, is pathognomonic but uncommon. In suspected esophageal rupture, Meckler triad of vomiting, lower chest pain, and cervical subcutaneous emphysema should raise immediate concern.
Evaluation must focus on excluding secondary causes, particularly esophageal rupture. Chest radiography is the most valuable initial test and should include a lateral view, as mediastinal air may be missed on a standard posteroanterior film. Radiographic findings may include mediastinal air outlining cardiac borders, subcutaneous emphysema, the continuous diaphragm sign, or the spinnaker sail sign in pediatric patients. Up to one-third of cases may have a normal chest radiograph. Chest CT is the imaging modality of choice when suspicion remains high despite a negative radiograph and is more sensitive for small air collections and associated pathology. If esophageal rupture is suspected, a water-soluble contrast esophagram is indicated. Laboratory studies are generally not diagnostic but should include CBC if mediastinitis is a concern.
Management depends on the underlying cause. Spontaneous pneumomediastinum is usually benign and self-limited, resolving within several days. Treatment consists of oxygen supplementation, analgesia, rest, and reassurance. High-flow oxygen may accelerate reabsorption of mediastinal air. Oral intake should be withheld if an esophageal source is suspected until diagnostic evaluation is complete. Secondary pneumomediastinum requires directed therapy toward the underlying condition, such as management of asthma exacerbation, diabetic ketoacidosis, trauma, or esophageal injury. Broad-spectrum antibiotics are indicated if mediastinitis is suspected. Tube thoracostomy is reserved for associated significant pneumothorax, and pericardiocentesis is indicated only in tension pneumopericardium with hemodynamic compromise.
Admission is warranted for secondary pneumomediastinum, suspected esophageal rupture, associated pneumothorax, abnormal vital signs, significant comorbidities, or unreliable follow-up. Patients with uncomplicated spontaneous pneumomediastinum, stable vital signs, no pneumothorax, and symptom improvement after observation may be discharged with close outpatient follow-up. Recurrent cases may require cardiothoracic evaluation.
Clinicians must maintain a high index of suspicion in patients with chest pain, dyspnea, and neck swelling, particularly in the setting of vomiting, asthma exacerbation, or inhalational drug use. Although often benign, failure to exclude esophageal rupture or other serious secondary causes can result in significant morbidity and mortality.
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Emergency And Acute Medicine – Pneumocystis Pneumonia
Pneumocystis pneumonia, commonly referred to as PCP, is caused by Pneumocystis jirovecii and remains the most common opportunistic infection in patients with HIV, particularly when the CD4 count is less than 200 cells/mm³. Although previously known as Pneumocystis carinii pneumonia, the organism is now classified as a fungus. Transmission is believed to occur via the respiratory aerosol route. Organisms colonize the respiratory tract, cysts rupture, and trophozoites proliferate within the alveoli, producing a characteristic foamy exudate that interferes with gas exchange. Most cases likely represent reactivation of latent infection, although person-to-person transmission has been suggested. PCP also occurs in patients with impaired cellular immunity due to cancer, chronic corticosteroid therapy, organ transplantation, or malnutrition. In children, infection tends to be more severe.
The clinical presentation is typically subacute. Up to 7% of patients may initially be asymptomatic. Patients often report fever, nonproductive or minimally productive cough, and progressive dyspnea. In HIV-positive patients, symptoms may develop gradually over weeks to months, whereas in non–HIV immunocompromised hosts the course may progress over days. Dyspnea on exertion with exercise-induced oxygen desaturation is common. Associated symptoms include chills, fatigue, weight loss, and chest discomfort. Patients receiving inhaled pentamidine prophylaxis may present with milder pulmonary symptoms but have a higher incidence of pneumothorax and extrapulmonary disease. On examination, tachypnea and tachycardia are common, and lung auscultation may reveal crackles or rhonchi, although findings can be minimal relative to the degree of hypoxemia.
Essential evaluation includes complete blood count, electrolytes, arterial blood gas, lactate dehydrogenase (LDH), blood cultures, and chest imaging. Arterial blood gas analysis should be obtained in all suspected cases to calculate the alveolar–arterial gradient, which is usually elevated. Adjunctive corticosteroids are indicated when the A–a gradient exceeds 35 mm Hg or the PaO₂ is less than 70 mm Hg. LDH is often elevated in HIV-associated PCP and higher levels may correlate with worse prognosis, though it is nonspecific. Chest radiography classically demonstrates bilateral interstitial or diffuse alveolar infiltrates. However, up to 25% of patients may have a normal radiograph early in the disease. Atypical findings include lobar infiltrates, cysts, pneumothoraces, pleural effusions, or nodular infiltrates. High-resolution CT is highly sensitive and typically shows patchy ground-glass opacities.
Definitive diagnosis requires identification of Pneumocystis organisms in respiratory specimens. Induced sputum examination has high specificity but variable sensitivity depending on specimen quality and laboratory expertise, and it is less sensitive in non–HIV patients or those on pentamidine prophylaxis. Bronchoalveolar lavage is recommended when induced sputum is nondiagnostic and clinical suspicion remains high, with sensitivity approaching 80–100%.
Initial management follows airway, breathing, and circulation principles. Supplemental oxygen should be administered, escalating from nasal cannula to nonrebreather mask as needed. Endotracheal intubation is required for refractory hypoxemia or hypercapnic respiratory failure. Intravenous fluids should be given for hypotension or dehydration. Empiric antimicrobial therapy should be initiated promptly when PCP is suspected. Intravenous trimethoprim–sulfamethoxazole is the first-line therapy and should be continued for 21 days. Intravenous pentamidine is an alternative for patients intolerant of first-line therapy. Oral therapy may be appropriate in mild cases. Alternative regimens include trimethoprim–dapsone, clindamycin–primaquine, or atovaquone. Adjunctive corticosteroids must be started within the first 72 hours in patients with significant hypoxemia to reduce mortality and the risk of respiratory failure. Suspected PCP patients should be isolated from other immunocompromised individuals.
Admission is indicated for moderate to severe disease, defined by hypoxemia or elevated A–a gradient, inability to tolerate oral medications, or unreliable follow-up. Intensive monitoring is required for patients with respiratory compromise. Selected patients with mild disease, stable oxygenation, and reliable follow-up may be managed as outpatients. Close follow-up with an infectious disease specialist is essential.
PCP should always be considered in immunocompromised patients presenting with dyspnea and diffuse infiltrates, particularly those with HIV or suspected undiagnosed HIV infection. Well-appearing patients with unexpectedly low oxygen saturation are at higher risk for rapid deterioration. Clinicians must also consider coexisting infections such as tuberculosis or atypical bacterial pneumonia in this population.
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Emergency And Acute Medicine – Plant Poisoning
Plant exposure is one of the most common reasons for contacting a poison center, and the majority of cases involve unintentional ingestion in children younger than 6 years. Accurate identification of the ingested plant is critical whenever possible, as toxicity varies widely depending on species and toxin class. Plants may produce toxicity through anticholinergic compounds, cardiac glycosides, nicotine-like alkaloids, cyanogenic compounds, calcium oxalate crystals, pyrrolizidine alkaloids, sodium channel activators, or toxalbumins.
Plants with anticholinergic properties such as jimson weed and deadly nightshade act as competitive antagonists at muscarinic receptors and produce the classic toxidrome of dry, warm, flushed skin, urinary retention, absent bowel sounds, and agitated delirium. Plants containing cardiac glycosides such as foxglove and oleander inhibit the sodium–potassium ATPase pump and cause digoxin-like toxicity, including gastrointestinal symptoms, bradycardia, tachydysrhythmias, and hyperkalemia. Nicotine-like alkaloid–containing plants such as tobacco and poison hemlock stimulate nicotinic receptors, leading to hypertension and tachycardia early, followed by bradycardia, muscle weakness, and respiratory failure in severe cases.
Cyanogenic plants such as apricot, cherry, and cassava are metabolized to cyanide and interfere with cellular respiration, causing abdominal pain, altered mental status, lactic acidosis, seizures, cardiovascular collapse, and multiorgan failure. Calcium oxalate–containing plants such as dumb cane and philodendron release microscopic crystals that cause immediate burning pain, oral swelling, and potential airway compromise; ocular exposure results in keratoconjunctivitis. Pyrrolizidine alkaloid–containing plants may cause acute hepatitis and, with chronic exposure, hepatic veno-occlusive disease. Sodium channel–activating plants such as aconite and rhododendron may produce gastrointestinal symptoms, bradycardia with atrioventricular block, tachydysrhythmias, seizures, and cardiovascular instability. Toxalbumin-containing plants such as castor bean interfere with ribosomal function and can cause severe systemic toxicity depending on route and dose.
In pediatric patients, lip, tongue, and oropharyngeal irritation is common, especially with calcium oxalate plants, and airway compromise is a concern. Children often ingest concentrated plant parts such as seeds or berries, which increases toxicity risk. Even small amounts of certain plants, such as yellow oleander leaves or jimson weed seeds, may be life-threatening.
Diagnosis is primarily clinical and depends on history, plant identification, and toxidrome recognition. Laboratory evaluation may include electrolytes, renal function, glucose, liver function tests, and blood gas analysis for acid–base status. Digoxin levels should be obtained in suspected cardiac glycoside poisoning. Lactate measurement is useful in suspected cyanogenic toxicity. Electrocardiography is essential in patients with suspected cardiotoxic plant ingestion.
Prehospital care focuses on airway, breathing, and circulation. Syrup of ipecac is not recommended. Plant material should be collected in a paper bag for identification.
Emergency department management is largely supportive. Airway protection and cardiac monitoring are priorities. Intravenous fluids should be administered for dehydration or hypotension, with vasopressors initiated if fluid resuscitation fails. Anticholinergic agitation is treated with benzodiazepines, and physostigmine may be considered for severe delirium. Cardiac glycoside toxicity with significant bradycardia, tachydysrhythmias, or hyperkalemia warrants digoxin-specific antibody fragments. Cyanogenic toxicity with severe lactic acidosis or hemodynamic instability should be treated with hydroxocobalamin or a cyanide antidote kit. Atropine is indicated for bradycardia associated with sodium channel–active plant toxins. Calcium oxalate exposures are managed with irrigation, analgesia, and airway monitoring. Toxalbumin and pyrrolizidine alkaloid exposures require supportive care and specialist consultation.
Patients require admission if they develop dysrhythmias, refractory hypotension, altered mental status, intractable vomiting, metabolic acidosis, or evidence of end-organ damage. Children should be admitted with a lower threshold due to smaller lethal doses and less specific symptoms. Patients may be discharged if they return to baseline mental status, tolerate oral intake, demonstrate stable cardiac function, and have no anticipated delayed toxicity.
Death from unintentional plant ingestion is rare, but intentional ingestion, misuse of herbal preparations, or consumption of highly toxic species can be fatal. Early recognition of toxidromes and consultation with poison control or a medical toxicologist are essential to optimize outcomes.
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Emergency And Acute Medicine – Pneumonia in Adults
Pneumonia in adults is an acute infection of the lung parenchyma and is the seventh leading cause of death and the leading infectious cause of mortality in the United States. Mortality is highest in elderly patients and those with chronic heart, lung, liver, or kidney disease, diabetes mellitus, alcoholism, malignancy, asplenia, immunosuppression, or recent antimicrobial use. Pneumonia is classified by source as community-acquired (CAP), healthcare-associated (HCAP), hospital-acquired (HAP), or ventilator-associated (VAP), and by presentation as typical or atypical. Complications include bacteremia, sepsis, lung abscess, empyema, and respiratory failure.
The most common cause of community-acquired pneumonia is Streptococcus pneumoniae. Other typical CAP pathogens include Haemophilus influenzae, Klebsiella pneumoniae, Moraxella catarrhalis, Streptococcus pyogenes, and Staphylococcus aureus. Atypical CAP pathogens include Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, and respiratory viruses. Healthcare- and hospital-associated pneumonias are more commonly caused by gram-negative organisms such as Pseudomonas and Stenotrophomonas, as well as methicillin-resistant Staphylococcus aureus (MRSA). Immunocompromised patients are at risk for organisms such as Mycobacterium tuberculosis and Pneumocystis jirovecii. Aspiration pneumonia may involve chemical pneumonitis with or without oral and gastric anaerobes.
Typical pneumonia presents with acute onset of fever, chills, rigors, productive cough, dyspnea, and pleuritic chest pain. Atypical pneumonia has a more subacute onset with a viral prodrome, nonproductive cough, low-grade fever, headache, myalgias, and malaise, often without pleuritic pain or rigors. On examination, patients may demonstrate tachypnea, tachycardia, hypoxia, and fever. Lung findings can include dullness to percussion, increased tactile fremitus, egophony, rales, rhonchi, or decreased breath sounds, although pneumonia may be present without classic consolidation findings. Elderly patients frequently present atypically, sometimes with confusion or functional decline as the primary symptom.
Diagnosis is based on clinical findings supported by imaging. Laboratory evaluation generally includes a complete blood count and serum chemistry panel. Blood and sputum cultures are typically reserved for ICU patients. Urine antigen testing for S. pneumoniae and Legionella may be helpful in select cases. Lactate levels may assist in identifying sepsis. Chest radiography is the primary imaging modality and may demonstrate consolidation, air bronchograms, interstitial infiltrates, pleural effusion, empyema, or cavitation. Radiographic findings are nonspecific for particular pathogens. Imaging may be deferred in young, healthy patients treated empirically as outpatients, and a negative radiograph does not exclude pneumonia if clinical suspicion is high.
Initial management includes supplemental oxygen, IV access, fluid resuscitation when indicated, cardiac monitoring, bronchodilators if bronchospasm is present, and airway management in cases of severe respiratory distress. Empiric antibiotic therapy should follow established guidelines. Previously healthy outpatients may receive azithromycin or doxycycline. Patients with significant comorbidities should receive a β-lactam plus macrolide combination or a respiratory fluoroquinolone alone. Inpatients not requiring ICU care may receive a β-lactam plus macrolide or a respiratory fluoroquinolone. ICU patients should receive a β-lactam plus either a macrolide or respiratory fluoroquinolone, with additional coverage for Pseudomonas or MRSA when risk factors are present. Aspiration pneumonia may require anaerobic coverage such as clindamycin or metronidazole. Prompt antibiotic administration is critical in ill-appearing patients.
Disposition decisions are guided by clinical judgment and validated tools such as the CURB-65 score and the Pneumonia Severity Index. CURB-65 evaluates confusion, elevated BUN, respiratory rate ≥30, hypotension, and age ≥65. Scores of 0–1 generally support outpatient management, while higher scores favor admission and possible ICU care. Admission is also indicated for unstable vital signs, hypoxia, significant comorbidities, failure of outpatient therapy, or inability to ensure follow-up. Discharge may be appropriate for patients younger than 65 without comorbidities, with normal vital signs and reliable follow-up within 72 hours.
Clinicians must avoid delays in antibiotic initiation in critically ill patients and remain vigilant for pneumonia in those presenting with presumed exacerbations of chronic lung disease. Tuberculosis and HIV risk factors should always be assessed. Elderly and immunocompromised patients may lack classic symptoms, making a high index of suspicion essential for timely diagnosis and management.
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KembaraXtra -Medicine- Emergency and Acute Medicine – Perforated Viscus
A perforated viscus is a full-thickness disruption of a hollow abdominal organ that allows gastrointestinal contents to spill into the peritoneal cavity. This results in chemical and bacterial peritonitis, leading rapidly to systemic inflammatory response and potential septic shock. Perforation may occur from ulceration, inflammation, obstruction, ischemia, trauma, or iatrogenic injury. It is a surgical emergency requiring rapid recognition and intervention.
The most common cause is perforated peptic ulcer disease, frequently associated with NSAID use or Helicobacter pylori infection. Other causes include small bowel ischemia, inflammatory bowel disease, neoplasms, foreign bodies, diverticular disease, appendicitis, penetrating or blunt abdominal trauma, endoscopic procedures, and radiation enteritis or proctitis. In pediatric patients, trauma is the most common cause, particularly in neonates after difficult delivery, nonaccidental trauma, motor vehicle collisions, or falls. The jejunum is a common rupture site in children.
Patients typically present with sudden, severe abdominal pain that is initially localized but rapidly becomes diffuse as peritonitis develops. Examination reveals rigidity, guarding, rebound tenderness, and absent bowel sounds. Systemic findings may include fever, tachycardia, tachypnea, and hypotension. In advanced cases, patients may present in hypovolemic or septic shock. Elderly patients often have atypical presentations with less pronounced pain, minimal guarding, absence of leukocytosis, altered mental status, hypothermia, or blunted tachycardia due to medications or comorbidities.
The essential initial study is an upright chest radiograph to detect pneumoperitoneum. After the patient has been upright for 5–10 minutes, as little as 1–2 mL of free air may be visualized under the diaphragm. Sensitivity ranges from 50% to 85%. A left lateral decubitus abdominal radiograph may be more sensitive than a supine film. The double wall (Rigler) sign, in which both the mucosal and serosal surfaces of bowel are visible, suggests free intraperitoneal air. Abdominal CT is highly sensitive for detecting small amounts of free air and is indicated when clinical suspicion remains high despite normal plain films.
Laboratory evaluation includes CBC, electrolytes, renal function, glucose, liver function tests, coagulation profile, urinalysis, lipase, arterial blood gas, and lactate. Leukocytosis and elevated lactate support the diagnosis but are not required. Type and cross-match should be performed in unstable patients. ECG may be necessary to exclude cardiac causes of abdominal pain. In pregnant patients, ectopic pregnancy must be excluded.
Management begins with aggressive resuscitation following trauma and sepsis principles. Hypotension and tachycardia are treated with rapid infusion of 0.9% normal saline, typically 500 mL to 1 L boluses in adults, repeated as needed. Pediatric patients receive 20 mL/kg boluses. Vasopressors may be required if fluids are insufficient. Nasogastric decompression and Foley catheter placement are recommended. Broad-spectrum intravenous antibiotics must be administered promptly to cover enteric gram-negative bacilli, gram-positive cocci, and anaerobes. Appropriate regimens include a carbapenem, piperacillin–tazobactam, or a third- or fourth-generation cephalosporin combined with metronidazole. Analgesia should be provided without delaying surgical consultation.
Immediate surgical consultation is mandatory for all suspected or confirmed cases. Imaging should not delay operative intervention in unstable patients. Discharge is not appropriate, as perforated viscus is a surgical emergency requiring admission and definitive management. Early recognition, prompt antibiotic therapy, aggressive resuscitation, and urgent surgical intervention are critical to reducing morbidity and mortality.
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KembaraXtra -Medicine- Emergency and Acute Medicine – Pemphigus
Pemphigus is a rare, IgG-mediated autoimmune blistering disorder of the skin and mucous membranes characterized by loss of keratinocyte cell-to-cell adhesion (acantholysis). The term is derived from the Greek word for “bubble” or blister. It most commonly affects older adults, with a median age of 71 years, and has a slight female predominance. Although rare, it can occur in neonates, children, and adolescents. If untreated, mortality historically reached 60–90%, but with modern therapy this has decreased to approximately 5%. Mortality is highest in patients with extensive mucocutaneous involvement.
There are three major subtypes. Pemphigus vulgaris accounts for 70–80% of cases and is the most serious form, with deeper mucocutaneous involvement. Up to 70% of patients initially present with painful oral lesions before cutaneous involvement develops. Autoantibodies are directed against desmoglein (Dsg) 1 and 3. Pemphigus foliaceus is more superficial, limited primarily to the skin, and associated with antibodies to Dsg1 only; oral lesions are uncommon and prognosis is generally better. Paraneoplastic pemphigus is often severe and associated with lymphoreticular malignancies. Endemic pemphigus foliaceus (fogo selvagem) is reported most commonly in South America and may be associated with environmental triggers such as insect bites.
The pathogenesis involves IgG autoantibodies targeting desmosomal cadherins (desmoglein 1 and 3) on keratinocytes. This immune attack results in acantholysis, cytoskeletal disruption, and apoptosis, leading to intraepidermal blister formation. Genetic predisposition is associated with certain HLA haplotypes, including DR4 and DRw6. Drug-induced pemphigus-like reactions have been reported with agents such as penicillamine, captopril, rifampin, piroxicam, and phenobarbital.
Clinically, patients present with flaccid bullae that rupture easily, leaving painful erosions with shreds of detached epithelium. Mucosal involvement, especially painful oral erosions, is common in pemphigus vulgaris and may precede skin findings. Lesions may spread to the scalp, chest, axillae, and groin. Crusted erosions, exfoliative plaques, and postinflammatory hyperpigmentation are common. The Nikolsky sign—epidermal separation with lateral pressure—is characteristic but not highly sensitive or specific. Without treatment, lesions persist and may lead to dehydration, malnutrition, infection, or sepsis.
Diagnosis is suspected clinically but requires confirmation with skin biopsy and direct immunofluorescence testing, which demonstrate intraepidermal blistering and intercellular IgG deposition. Serum antibody titers (indirect immunofluorescence or ELISA) may correlate with disease activity but are not typically obtained in the emergency setting. The differential diagnosis includes bullous pemphigoid, toxic epidermal necrolysis, dermatitis herpetiformis, erythema multiforme, lupus erythematosus, herpes simplex infection, and other blistering or erosive dermatoses.
Emergency management depends on severity. Mild-to-moderate disease may be managed with oral prednisone and urgent dermatology follow-up. Systemic corticosteroids remain the cornerstone of therapy. Severe disease may require high-dose corticosteroids, pulse intravenous methylprednisolone, or admission for plasmapheresis. Adjuvant immunosuppressive therapies such as azathioprine, mycophenolate, cyclophosphamide, cyclosporine, IV immunoglobulin, or rituximab may be added in refractory cases. Patients presenting with hypotension or sepsis require aggressive fluid resuscitation, broad-spectrum antibiotics if infection is suspected, and stress-dose steroids in those on chronic corticosteroids.
Admission is indicated for first-time presentations requiring biopsy and diagnostic confirmation, extensive mucocutaneous involvement, intractable pain, secondary infection, or signs of systemic compromise. ICU or burn unit admission may be necessary in cases of shock, sepsis, or large body surface involvement requiring intensive wound care. Patients with mild disease who are stable may be discharged with prompt dermatology follow-up.
Key clinical principles include recognizing early mucosal involvement, understanding that long-term immunosuppression is often required, and maintaining vigilance for complications such as adrenal crisis, severe infection, or steroid-induced metabolic derangements. Early diagnosis and coordinated dermatologic management significantly improve outcomes.
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KembaraXtra -Medicine- Emergency and Acute Medicine – Pericarditis
Pericarditis is inflammation, infection, or infiltration of the pericardial sac surrounding the heart. A pericardial effusion may or may not be present. Acute pericarditis has a rapid onset and may be complicated by cardiac tamponade if significant fluid accumulates. Constrictive pericarditis results from chronic inflammation leading to thickening, fibrosis, and adherence of the pericardium to the myocardium, impairing diastolic filling.
The most common cause is idiopathic, presumed viral in many cases. Viral etiologies include coxsackievirus, echovirus, adenovirus, Epstein–Barr virus, cytomegalovirus, hepatitis B, HIV, and others. Bacterial causes include tuberculosis, staphylococcal and streptococcal species, Haemophilus, Salmonella, and Legionella. Fungal, parasitic, neoplastic, uremic, autoimmune, post–myocardial infarction (Dressler syndrome), radiation, trauma, postpericardiotomy, aortic dissection, myxedema, pancreatitis, inflammatory bowel disease, amyloidosis, and drug-induced causes are also recognized.
Chest pain is the hallmark symptom. It is typically sharp, pleuritic, and substernal, worsened by lying supine or coughing, and improved by sitting up or leaning forward. Pain may radiate to the trapezius ridge due to phrenic nerve irritation. Associated symptoms include fever, mild dyspnea, cough, hoarseness, nausea, and anorexia. A history of recent viral illness, autoimmune disease, malignancy, or prior pericarditis episodes is common.
On examination, tachycardia and tachypnea may be present. A pericardial friction rub is highly specific and best heard at the lower left sternal border, often accentuated when the patient leans forward. The classic rub is triphasic, with presystolic, systolic, and early diastolic components, though any combination may be heard. If a significant effusion develops, features of cardiac tamponade may appear, including hypotension, jugular venous distention, and muffled heart sounds. Pulsus paradoxus may be present. Constrictive pericarditis produces signs of right- and left-sided heart failure such as peripheral edema, ascites, hepatic congestion, and pulmonary edema.
Electrocardiography typically demonstrates four classic stages. Stage 1 shows diffuse concave ST elevation with PR depression, except in aVR and V1. Stage 2 reveals normalization of ST and PR segments with T-wave flattening. Stage 3 shows diffuse T-wave inversion. Stage 4 reflects normalization of T waves. Electrical alternans suggests a significant effusion. Cardiac enzymes may be mildly elevated in myopericarditis but are useful to distinguish from acute myocardial infarction.
Laboratory studies may show leukocytosis and elevated inflammatory markers such as ESR and C-reactive protein. Chest radiograph is usually normal unless more than 250 mL of fluid has accumulated, in which case cardiomegaly may be visible. Echocardiography is the diagnostic modality of choice for detecting pericardial effusion and can identify even small fluid collections. CT scanning can detect pericardial thickening or calcifications, particularly in constrictive pericarditis. Pericardiocentesis is reserved for diagnostic clarification or therapeutic relief in tamponade.
Initial management follows standard airway, breathing, and circulation principles. Emergent pericardiocentesis is indicated in hemodynamically unstable patients with tamponade. Most cases of idiopathic or viral pericarditis are treated with nonsteroidal anti-inflammatory drugs. Ibuprofen or aspirin are commonly used and may be tapered gradually to reduce recurrence. Colchicine is recommended in combination with NSAIDs to decrease recurrence rates and may be continued for approximately three months. Corticosteroids are reserved for refractory cases, autoimmune causes, or when NSAIDs are contraindicated, as they are associated with higher recurrence rates. Bacterial pericarditis requires urgent IV antibiotics and drainage. Uremic pericarditis requires intensified dialysis. Neoplastic pericarditis is managed in conjunction with oncology.
Patients with hemodynamic instability, cardiac tamponade, malignant arrhythmias, large effusions, anticoagulation use, high fever, immunosuppression, trauma, malignancy, or suspected bacterial etiology require hospital admission, often to a monitored or intensive care setting. Stable patients with mild symptoms and no high-risk features may be managed as outpatients with close follow-up.
The classic presentation includes a recent viral illness followed by sharp, positional chest pain and a friction rub. Distinguishing pericarditis from acute myocardial infarction and other causes of chest pain is critical. NSAIDs remain the cornerstone of therapy, and most patients improve within two weeks with appropriate treatment.
