A patient received atropine intravenously before surgery

Question

The recovery room nurse notes that the patient is delirious upon awakening, has a heart rate of 96 beats per minute, a respiratory rate of 22 breaths per minute, and a blood pressure of 110/78 mm Hg. The nurse notifies the anesthesiologist, who will order:
a. activated charcoal to minimize intestinal absorption of the antimuscarinic agent.
b. an acetylcholinesterase inhibitor to compete with the antimuscarinic agent at receptors.
c. an antipsychotic medication to treat the patient's central nervous system symptoms.
d. ipratropium bromide (Atrovent) to counter the respiratory effects of the antimuscarinic agent.

Answer 1

ANS: B
This patient is showing signs of antimuscarinic toxicity, caused by the atropine given during surgery. The most effective antidote is physostigmine, which inhibits acetylcholinesterase, allowing acetylcholine to build up at cholinergic junctions and compete with the antimuscarinic agent for receptor binding. Activated charcoal is only useful if an antimuscarinic agent has been ingested, because it impedes absorption from the GI tract. Because this patient's psychotic symptoms are caused by an antimuscarinic agent, physostigmine should be given to treat the cause; an antipsychotic medication would only treat the symptom. Ipratropium bromide is an antimuscarinic agent and would only compound the effects. This patient's respiratory rate is only mildly elevated.