Final answer:
In a cholinergic crisis associated with myasthenia gravis, a nurse should administer Atropine to manage the symptoms by reversing the excessive muscarinic effects of acetylcholine.
Step-by-step explanation:
A nurse in the emergency department who is caring for a client with myasthenia gravis in a cholinergic crisis should plan to administer Atropine. Myasthenia gravis is an autoimmune disorder where antibodies block acetylcholine receptors, causing muscle weakness. In a cholinergic crisis, there is an excess accumulation of acetylcholine due to an overdose of acetylcholinesterase inhibitors such as pyridostigmine or neostigmine. Atropine is used as an anticholinergic medication to reverse the muscarinic effects of excessive acetylcholine levels, thereby managing the symptoms of a cholinergic crisis.