The Poisoned Patient

General Principles

  • Patients who present to the hospital with an overdose or toxic exposure can be challenging for the clinician. This section will review the general approach to the poisoned or potentially poisoned patient. Specific toxins will be discussed in the sections that follow.
  • When managing the poisoned patient, prioritize basic supportive care measures, including airway protection and support of respiration and circulation.

Definition

  • A toxidrome, or toxic syndrome, is a constellation of clinical examination findings that assists in the diagnosis and treatment of the patient who presents following an exposure to an unknown agent.
  • The toxidromes are generally defined by vital signs, pupillary diameter, skin and mucous membrane findings, and mental status. In certain cases, bowel and bladder function may also be relevant. See Table 28-1.
Table 28-1: Toxidromes


Vital
Signs


Physical Exam Character­istics






ToxidromeMechanism/PharmacologyHRBPTempRRMental StatusPupilsSkin/Mucous MembranesMotor ActivityReflexesGI MotilityCommon AgentsPearls
Sympathomi­meticα and β adrenergic stimulation through increased secretion, impaired reuptake, or direct effect of an agent↑↑↔ to ↑↔Excited ± deliriumDilatedDiaphoretic/flushedIncreased voluntary movement (psychomotor agitation)↔↔ to ↓ (with local GI exposure such as body “stuffers”)Cocaine, amphetamines, synthetic cathinones (“bath salts”), vasopressors, bupropionEffective and timely management of excited delirium is potentially lifesaving. The combination of metabolic acidosis, physical restraint impairing effective ventilation, and chemical sedation impairing respiratory drive is dangerous
CholinergicProximate effects on stimulation of ACh-mediated postsynaptic muscarinic receptors. Delayed effects on stimulation of presynaptic ACh-mediated nicotinic receptors↓↔↔ to ↓↓Depressed or obtundedSmall/
pinpointExcess oral/respiratory secretionsOverall, decreased. Fasciculations/seizures possible↓↑ (diarrhea, urinary incontinence)Nerve agents, organophosphate/carbamate pesticides, carbamate pharmaceuticals (e.g., neostigmine)Early treatment of the “killer Bs,” bradycardia, bronchorrhea, and associated respiratory impairment with atropine is imperative for nerve agent/pesticide poisoning
AnticholinergicInhibition of postsynaptic muscarinic receptors↑↔ to ↑↑↔Agitation with delirium, hallucinations, picking at surroundingsDilatedDry (lack of axillary moisture)Overall, decreased. Often fighting/picking at surroundings↔↓ (decreased bowel sounds, urinary retention)First-generation antihistamines, tricyclic antidepressants, jimson weed, atropine, scopolamine, hyoscyamineSome cases may present with delirium absent other physical findings, “central anticholinergic syndrome”
OpioidStimulation of μ-opioid receptors↔ to ↓ (depending on degree of respiratory depression)↔↔ to ↓↓↓Depressed or obtundedSmall/
pinpoint↔Decreased↔↓ (constipation with chronic use)Opiates (morphine, codeine, diacetylmorphine [heroin]); opioids (fentanyl, oxycodone, hydrocodone, hydromorphone)
SympatholyticStimulation of imidazoline receptors or in some cases alpha-2 agonism↓↓↔ to ↓↓Depressed or obtundedSmall/
pinpoint↔Decreased↔↔ to ↓Imidazolines (e.g., oxymetazoline, dexmedetomidine, clonidine)

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