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Correspondence to Dr Robert J Hoffman; [email protected]
KEY POINTS
Recognition of toxidromes is useful in evaluation and management of poisoning.
History narrows the list of possible exposures.
Vital signs and physical examination allow initial prognostication for many poisonings.
Initial management should focus on stabilisation, decontamination and supportive care.
Most poisonings require only basic laboratory investigations.
A poison centre or a medical toxicologist can provide valuable management advice;www.ToxBase.org is a useful UK National Poison Information Service reference.
Background
The term toxidrome, a portmanteau of the words ‘toxicologic’ and ‘syndrome’, describes a distinct pattern of effects of poisoning. Well-defined toxidromes are the opioid, anticholinergic, cholinergic and sympathomimetic. An additionally described toxidrome is the GABAergic as noted in table 1. These are named for the receptor agonist or antagonist activity causing their specific pattern of clinical effects.
Table 1Toxidromes
| Toxidrome | Example agent | VS effects | Clinical findings | Antidote |
| Opioid | Fentanyl | T: – or ↓ BP: – or ↓ HR: – or ↓ RR: ↓ | CNS: somnolence Pupils: miosis Skin: – Misc: pulmonary oedema | Naloxone |
| Sympathomimetic | Cocaine | T: ↑ BP: ↑ HR: ↑ RR: – to ↑ | CNS: excitation Pupils: mydriasis Skin: diaphoretic, flushed Misc: tremor | None |
| Anticholinergic | Diphenhydramine | T: ↑ BP: ↑ HR: ↑ RR: – or ↑ | CNS: delirium Pupils: mydriasis Skin: dry, flushed Misc: urinary retention, ↓ bowel sounds | Physostigmine |
| Cholinergic | Organophosphates | T: – BP: – HR: ↓ RR: ↑ | CNS: delirium PNS: weakness Pupils: miosis Skin: diaphoretic Misc: DUMBELS | Atropine |
| Pralidoxime | ||||
| GABAergic | Diazepam | T: – BP: – HR: – RR: – | CNS: somnolence, coma Pupils: variable Skin: – Misc: – | Flumazenil |
↑, increased; ↓, decreased; –, no change; BP, blood pressure; CNS, central nervous system; DUMBELS, diarrhoea, urination, miosis, bradycardia/bronchorrhoea/bronchospasm, emesis, lacrimation, salivation; HR, heart rate; Misc, miscellaneous; PNS, peripheral nervous system; RR, respiratory rate; T, temperature; VS, vital sign.
A review of toxidromes is typically included in the fundamental teaching of clinical toxicology.1 Understanding toxidromes provides insight to toxicodynamics, which are the effects a toxin exerts on patients, typically at the receptor level. In this review, toxidromes and the initial assessment and general approach to management of acute poisoning are discussed. This article details the receptor-level effects of the poisoning, key clinical signs and symptoms and the role antidotes play in treatment....