17.15: Toxidromes: Clinical Features

Toxidromes are specific patterns of symptoms resulting from toxic substance exposure. They help in the identification and treatment of poisoning. The symptoms of each toxidrome group indicate poisoning by a certain class of chemicals or drugs.

1. Sympathomimetic: Stimulates the sympathetic nervous system. Symptoms include agitation, increased heart rate (HR), blood pressure (BP), respiratory rate (RR), temperature, and pupil size. Drugs like cocaine and amphetamines, along with tremors and diaphoresis, can cause such symptoms.

2. Anticholinergic: Blocks acetylcholine, leading to symptoms such as delirium, increased HR, BP, RR, temperature, and pupil size. Examples are diphenhydramine and atropine, which can also cause ileus and flushing.

3. Cholinergic: Overstimulates the parasympathetic nervous system. Symptoms include somnolence, coma, decreased pupil size, increased salivation, lacrimation, urination, defecation, gastric cramping, emesis (SLUDGE), and muscle twitching (fasciculation). Organophosphates are a common cause.

4. Opioid: Activates opioid receptors, leading to somnolence, coma, decreased HR, BP, RR, and pupil size. Heroin and oxycodone are typical opioids.

5. Sedative-hypnotic: Depresses central nervous system activity, causing somnolence, coma, and decreased HR, BP, and RR. Benzodiazepines and barbiturates are examples.

6. Salicylate: Results from aspirin overdose, leading to confusion, increased HR, BP, RR, and temperature, with symptoms like diaphoresis and vomiting.

7. Calcium channel blocker: Affects cardiac function, leading to decreased HR and BP. Verapamil is an example.

Recognizing these patterns is critical for healthcare providers to manage poisoning effectively.

Toxidromes are distinct symptom patterns signaling drug or chemical overdose. Their recognition enables rapid diagnosis and treatment.

The most common toxidromes are anticholinergic, cholinergic, opioid, sympathomimetic, sedative and hypnotic.

Anticholinergic toxidrome results from muscarinic receptor inhibition and parasympathetic suppression causing dry flushed skin, hyperthermia, mydriasis, delirium, and reduced intestinal motility.

Cholinergic agents inhibit acetylcholinesterase, causing acetylcholine accumulation and muscarinic overstimulation.

Cholinergic toxidrome causes somnolence, coma, miosis, excessive salivation, diarrhea, gastric cramping, emesis, and muscle twitching.

Opioid overdose suppresses the CNS, typically causing miosis, respiratory depression, bradycardia, and reduced gut motility.

Next, sympathomimetic toxidrome results from sympathetic stimulation, leading to agitation, hypertension, tachycardia, mydriasis, tremors, sweating, and hyperthermia.

Sedatives and hypnotics cause drowsiness, respiratory depression, and diminished reflexes.