Atropine

The influence of atropine is most noticeable in healthy young adults in whom vagal tone is considerable. In infancy and old age, even large doses may fail to accelerate the heart.

Uses:
Asystole
EMD or PEA with ventricular rate <60/min
Sinus bradycardia – will increase BP as a result
Reversal of muscarinic effects of anticholinesterases (neostigmine)
Organophosphate poisoning

Contraindications:
Complete heart block
Tachycardia

Administration:
• Bradycardia: 0.3–1 mg IV bolus, up to 3 mg (total vagolytic dose), may be diluted with WFI
• Asystole: 3 mg IV bolus, once only
• EMD or PEA with ventricular rate <60/min: 3 mg IV bolus, once only
• Reversal of muscarinic effects of anticholinesterase: 1.2 mg for every 2.5 mg neostigmine
• Organophosphate poisoning: 1–2 mg initially, then further 1–2mg every 30 min PRN

How not to use atropine:
Slow IV injection of doses <0.3 mg (bradycardia caused by medullary vagal stimulation)

Adverse effects:
Drowsiness, confusion
Dry mouth
Blurred vision
Urinary retention
Tachycardia
Pyrexia (suppression of sweating)
Atrial arrhythmias and atrioventricular dissociation (without significant cardiovascular symptoms)
Dose >5 mg results in restlessness and excitation, hallucinations, delirium and coma

Cautions:
Elderly (↑ CNS side-effects)
Child with pyrexia (further ↑ temperature)
Acute myocardial ischaemia or MI (tachycardia may cause worsening)
Prostatic hypertrophy–urinary retention (unless patient’s bladder catheterised)
Paradoxically, bradycardia may occur at low doses (<0.3 mg)
Acute-angle glaucoma (further ↑ IOP)
Pregnancy (foetal tachycardia)