The Poisoned Patient

Definitions

• Poisoning: toxic exposure causing symptoms, usually unintentional.
• Overdose: usually intentional toxic exposure, including suicide attempts and recreational drug misuse.

Epidemiology

The highest-risk groups are children age 1–5 and the elderly.

Toxic exposure at age 6–12 is unusual → consider possible psychiatric/social concerns.

Emergency stabilization

Always prioritize:

1. Airway.
2. Breathing.
3. Circulation.

Then assess vitals, glucose, ECG, and labs; consider antidotes and decontamination.

“Coma cocktail”: the classic USMLE concept

For unexplained altered mental status: naloxone, thiamine, and dextrose (if hypoglycemic).

Think “loss of airway or ventilation.”

Common causes:

• Opioids → respiratory depression.
• Organophosphates → bronchorrhea.
• Corrosives → airway edema.
• Seizures (isoniazid, theophylline).
• Pulmonary edema.
• Severe CNS depression.

Basic labs

• CBC.
• CMP.
• Ethanol level.
• Acetaminophen level.
• Salicylate level.
• Coagulation studies.
• Drug screen.

ABG versus VBG

The handout favors ABG over VBG, especially for salicylates, carbon monoxide, and severe poisoning.

TCA overdose

Classic findings: wide QRS, arrhythmias, and a terminal R wave in aVR.

Treatment: sodium bicarbonate.

Digoxin toxicity

Can cause AV block, junctional rhythm, and ventricular arrhythmias.

Treatment: digoxin immune Fab.

Cocaine

Can cause MI, ST elevation/depression, and tachyarrhythmias.

Diphenhydramine and antihistamines

Can cause tachycardia, an anticholinergic toxidrome, and QT prolongation.

Opioid

Classic triad: CNS depression, respiratory depression, and pinpoint pupils.

Treatment: naloxone.

Anticholinergic

“Hot as a hare, blind as a bat…”

Findings: dry skin, mydriasis, urinary retention, delirium, and tachycardia.

Causes: diphenhydramine, TCAs, and atropine.

Cholinergic — organophosphates

SLUDGE:

• Salivation.
• Lacrimation.
• Urination.
• Diarrhea.
• GI upset.
• Emesis.

Plus: bronchorrhea and miosis.

Treatment: atropine and pralidoxime.

Sympathomimetic

Causes: cocaine and amphetamines.

Findings: tachycardia, hypertension, diaphoresis, mydriasis, and agitation.

Works best within 1 hour of ingestion.

Dose: adults 25–100 g; children 0.5–1 g/kg.

Contraindications

Do not give with:

• Caustic ingestion.
• An unprotected airway.
• Bowel obstruction.
• Hydrocarbon ingestion with aspiration risk.

Rarely used now.

Possible indications: massive life-threatening ingestion within approximately 1 hour.

Contraindications: caustics, hydrocarbons, and an unprotected airway.

Mnemonic: ME SALT

• Methanol.
• Ethylene glycol.
• Salicylates.
• Alcohols (toxic).
• Lithium.
• Theophylline.

Acetaminophen

Most common cause of acute liver failure.

• Antidote: N-acetylcysteine (NAC).
• Lab: AST/ALT elevation.
• Use the Rumack–Matthew nomogram.

Salicylate toxicity

Symptoms: tinnitus, tachypnea, and fever.

Acid-base pattern: mixed respiratory alkalosis + metabolic acidosis.

Treatment: sodium bicarbonate; dialysis if severe.

Avoid intubation if possible unless necessary, because worsening acidosis can occur.

Carbon monoxide

Symptoms: headache, cherry-red skin (rare), and flu-like illness.

Diagnosis: carboxyhemoglobin level.

Treatment: 100% oxygen; hyperbaric oxygen if severe.

Calcium channel blocker overdose

The handout identifies this as the most common cardiovascular drug overdose death.

Findings: bradycardia, hypotension, and hyperglycemia.

Treatment: calcium, high-dose insulin therapy, and vasopressors.

1. Remove contaminated clothing.
2. Brush off dry powders.
3. Irrigate copiously.

Drug packets usually contain cocaine or heroin.

Complications: bowel obstruction; packet rupture → massive overdose.

Management: surgery if rupture or obstruction.

USMLE pearls

• Wide QRS overdose → think TCA.
• Hypoglycemia + altered mental status → give dextrose.
• Alcoholic/confused patient → give thiamine before glucose.
• Organophosphates cause wet patients.
• Anticholinergics cause dry patients.
• Activated charcoal is ineffective for iron, lithium, and alcohols.
• Calcium channel blocker overdose → hyperglycemia.
• Salicylates cause a mixed acid-base disorder.
• Opioid overdose kills via respiratory depression.

One-minute board review

Sick poisoned patient approach:

1. ABCs.
2. Glucose.
3. ECG.
4. Acetaminophen/salicylate levels.
5. Identify the toxidrome.
6. Give an antidote if available.
7. Consider charcoal/dialysis when indicated.