Toxicological, Environmental, and Psychiatric Emergencies
Toxidromes and antidotes
Candidates must recognize the classic toxidromes: anticholinergic (dry, flushed, hot, dilated pupils, delirium, urinary retention), cholinergic (salivation, lacrimation, urination, diarrhea, bronchospasm, bradycardia), sympathomimetic (tachycardia, hypertension, agitation, dilated pupils, sweating), opioid (pinpoint pupils, respiratory depression, decreased consciousness), and sedative-hypnotic (decreased consciousness with normal pupils and respirations). Know key antidotes: naloxone for opioids, acetylcysteine for acetaminophen, sodium bicarbonate for salicylates and tricyclic cardiotoxicity, calcium for hydrofluoric acid and calcium channel blocker overdose, glucagon and high-dose insulin for beta blocker overdose, and hydroxocobalamin for cyanide. Decontamination decisions depend on time and route; activated charcoal is not universal.
Environmental emergencies
Heat stroke is hyperthermia with central nervous system dysfunction; cooling is the priority and antipyretics do not work. Hypothermia requires gentle handling and rewarming; ventricular fibrillation can be refractory until rewarmed. Drowning care focuses on hypoxia and respiratory support. Electrical injury can cause deep tissue damage and dysrhythmia despite small surface wounds. Carbon monoxide poisoning presents with headache and confusion; treat with high-flow oxygen and consider hyperbaric therapy.
Psychiatric emergencies
Safety first: assess risk of harm to self or others, secure the environment, and use de-escalation before restraint. Medical causes of agitation must be excluded: hypoglycemia, hypoxia, head injury, sepsis, and intoxication or withdrawal. Alcohol withdrawal can progress to seizures and delirium tremens, which is a medical emergency.
Traps in questions
- Anticholinergic and sympathomimetic toxidromes both cause tachycardia and dilated pupils; sweating and bowel sounds help distinguish them.
- Naloxone may precipitate withdrawal; titrate to breathing, not to full alertness.
- Do not assume agitation is psychiatric without checking glucose and oxygen.
- Antipyretics are useless in heat stroke.
Rule of thumb
Treat the airway and breathing before the toxin. Worked example: an unresponsive patient with pinpoint pupils and a respiratory rate of 6 receives bag-mask ventilation and titrated naloxone.