clinical presentation

copied shamelessly from LITFL

CVS – dry mucous membranes, tachycardia, hypertension → hypotension → arrhythmia; postural hypotension, dehydration
CNS – nystagmus, dizziness, agitation, ↓ LOC/coma, seizures, clonus, tremor, hypereflexia, pupillary dilation, blurred vision
GI – N+V, abdominal pain, dry mouth, ileus
METABOLIC – severe metabolic acidosis, fever, hypokalaemia
GU – urinary retention
SKIN – flushed

pathophysiology

anticholinergic effects
inhibition of catecholamine reuptake (initial increase in sympathetic tone -> prolonged decrease)
profound alpha-adrenergic blockade
sodium channel blockade → cardiotoxicity and CNS effects

ecg changes

Prolonged PR interval
Wide QRS
QT prolongation
terminal R wave >3mm in aVR

management

airway/breathing

A/B: if you have to tube, ventilate with a higher MV

circulation

Sodium bicarb if broad QRS - 50 mmol
Hypotension may be fluid refractory

disability

Seizures - treat with benzodiazepine
- avoid phenytoin
Agitation - benzodiazepine, e.g. midazolam (preferred for children) or diazepam (adults)

exposure

aim for pH 7.5-7.55
cooling - especially if body temp >38.5

toxic doses (Toxbase)


TCA or related	Adults
Amitriptyline	3 mg/kg
Amoxapine - discontinued in the UK	Any amount
Clomipramine	4 mg/kg
Desipramine	3 mg/kg
Dosulepin (Dothiepin)	3 mg/kg
Doxepin	4 mg/kg
Imipramine	4 mg/kg
Lofepramine	4.5 mg/kg
Loxapine	1 mg/kg
Maprotiline - discontinued in the UK	3 mg/kg
Nortriptyline	2.5 mg/kg
Opipramol - not available in the UK	6 mg/kg
Trimipramine	5 mg/kg

#pharmacology #toxicology

sources/links