Atropine on the NCLEX
Atropine for symptomatic bradycardia: ACLS dosing, anticholinergic effects, and the glaucoma contraindication.
Atropine blocks the vagus nerve. Every effect and every contraindication follows from that one sentence.
Symptomatic bradycardia
First-line drug for symptomatic bradycardia: hypotension, altered mentation, chest pain, signs of poor perfusion. ACLS dose: 1 mg IV, repeat every 3-5 minutes to a maximum of 3 mg. A slow rate with a fine blood pressure and a clear head gets monitoring, not atropine. If atropine fails, next steps are transcutaneous pacing or a dopamine or epinephrine infusion.
Where it works poorly
Atropine speeds the SA node through the vagus. In high-degree AV blocks (Mobitz II, third-degree) the problem sits below the node, so atropine often does little. Move to pacing early. Transplanted hearts are denervated and do not respond.
Anticholinergic effects
The classic string: hot as a hare, dry as a bone, red as a beet, blind as a bat, mad as a hatter. Fever, dry mouth, flushing, blurred vision with dilated pupils, confusion. Add urinary retention, constipation, and tachycardia. In an elderly patient, expect the confusion and retention to show up in the question.
The glaucoma contraindication
Atropine dilates the pupil, which closes the drainage angle. Contraindicated in angle-closure (narrow-angle) glaucoma: it can trigger an acute attack with severe eye pain and vision loss. Caution also in BPH (retention) and tachyarrhythmias. In a true code, the arrest outranks the contraindication.
The other atropine job
Antidote for organophosphate poisoning and cholinergic crisis: the SLUDGE patient (salivation, lacrimation, urination, defecation, GI cramping, emesis) drowning in secretions. Here you dose to effect, titrating until secretions dry.
Frequently asked
HR 42, BP 128/76, alert and asymptomatic. Give atropine?
No. Treat symptomatic bradycardia, not a number. Monitor and look for a cause.
Why avoid atropine in narrow-angle glaucoma?
Pupil dilation blocks aqueous drainage and can precipitate an acute angle-closure attack.
Atropine fails in third-degree block. Next?
Transcutaneous pacing. Prepare it while atropine is being tried, since it usually will not fix an infranodal block.
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