History
The history in patients with cyclic antidepressant (CA) poisoning may include either intentional or unintentional ingestion. Older children should be screened for suicidal ideation and prior self-harm. Onset of symptoms typically occurs within 2 hours, and major complications typically occur within the first 6 hours after exposure.
A history can be taken from the patient, if possible, witnesses, or family members. Details about the possible source of ingestion, past medical history, and co-ingestion of alcohol or illicit drugs should be elicited. [9] An attempt should be made to determine the specific agent ingested because the toxic profiles of different cyclic antidepressants may vary. For example, amoxapine is associated with a higher incidence of seizures, whereas maprotiline is more likely to be cardiotoxic. Both dothiepin (not available in the United States) and amitriptyline have been shown to have greater toxicity than the other cyclic antidepressants. [10]
Physical Examination
Physical examination findings relate to the antimuscarinic, cardiovascular, and central nervous system (CNS) effects of cyclic antidepressants. Antimuscarinic effects are typically the first to appear and should raise clinical suspicion of cyclic antidepressant overdose. One suggested aid to help identify and recall severe CA toxicity is the mnemonic "S-A-L-T" (ie, shock, altered mental status, long-QRS interval duration, terminal R wave in aVR). [3]
A targeted physical examination should assess the patient’s vital signs, and a brief neurologic assessment should include pupillary response and a gross motor and sensory examination. Classic symptoms of antimuscarinic syndrome include mydriasis, delirium, dry skin, fever, and flushing. Other antimuscarinic effects may include the following [9] :
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Xerostomia
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Blurred vision
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Urinary retention
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Hypoactive or absent bowel sounds
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Myoclonic twitching
Cardiorespiratory assessment and evaluation of the skin for temperature, moisture, and track marks can be done. Cardiovascular effects may include the following [9] :
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Sinus tachycardia
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Prolonged QRS and QT intervals
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Heart block
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Peripheral vasodilatation
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Hypotension
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Cardiogenic shock
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Ventricular dysrhythmias
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Asystole
CNS effects may include the following [9] :
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Drowsiness
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Extrapyramidal signs
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Rigidity
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Ophthalmoplegia
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Respiratory depression
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Seizure
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Coma
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Toxicity, antidepressant. ECG shows the terminal R wave in aVR and the widened QRS complex associated with tricyclic antidepressant (TCA) toxicity.
