The client is scheduled for a Tensilon test to check for Myasthenia Gravis. Which medication should be kept available during the test?

Appeared in: DHS Staff Nurse - 2018 (Shift-2nd)

Explanation

The Tensilon test uses edrophonium, a short-acting cholinesterase inhibitor, which increases acetylcholine levels at nerve junctions.
An excess of acetylcholine can cause a life-threatening 'cholinergic crisis,' characterized by severe bradycardia, bronchospasm, and hypotension.
Atropine sulphate is an anticholinergic drug that acts as a specific antidote by blocking the muscarinic effects of acetylcholine.
It is a critical safety measure to have atropine at the bedside to immediately reverse a cholinergic crisis if it occurs during the test.

Option B: Furosemide is a loop diuretic used to remove excess fluid from the body (e.g., in heart failure or edema). It has no effect on acetylcholine or its receptors.
Option C: Prostigmin (neostigmine) is also a cholinesterase inhibitor, similar to edrophonium but longer-acting. Administering it would worsen a cholinergic crisis by further increasing acetylcholine levels.
Option D: Promethazine is an antihistamine with antiemetic and sedative properties. It does not counteract the effects of a cholinergic crisis.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Pharmacological management and safety protocols for the Tensilon (edrophonium) test as background academic context rather than a clinical decision trigger.
The nurse's primary safety responsibility before a Tensilon test is to ensure that atropine and resuscitation equipment are immediately available at the patient's bedside.
Continuous monitoring of vital signs (heart rate, blood pressure, respiratory rate, and oxygen saturation) is critical during and immediately after the test to detect signs of a cholinergic crisis.
What if? If the patient's muscle weakness suddenly worsens and they become bradycardic after receiving edrophonium, it indicates a cholinergic crisis. The nurse's priority action is to administer the standby atropine as ordered and provide respiratory support.

How to Approach the Question

First, identify the procedure mentioned in the question: the Tensilon test.
Recall the drug used for this test (edrophonium) and its pharmacological class (short-acting cholinesterase inhibitor).
Consider the mechanism of action: it increases acetylcholine. The primary risk is an excess of this neurotransmitter, leading to a 'cholinergic crisis'.
The question asks for the safety medication that should be available. This means you need to identify the antidote for a cholinergic crisis.
Evaluate the options: Atropine is a classic anticholinergic drug used to block the effects of acetylcholine. The other options are a diuretic, another cholinesterase inhibitor, and an antihistamine, none of which are antidotes for a cholinergic crisis.

Concept Tested & Keywords

Concept Tested: Pharmacological management and safety protocols for the Tensilon (edrophonium) test.
Stem keywords: Tensilon test, Myasthenia Gravis, medication
Lead-in keywords: Which medication
Negative lead-in flag: false

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E6 Pharmacology Nursing Lilley 11e Part 2 p. 17-19

E6 Pharmacology Katzung 16e p. 183-185

Practise the full DHS Staff Nurse - 2018 (Shift-2nd)

Attempt every question from this paper in a timed mock, then review the full solution for each one.