Question

A patient was administered a muscle relaxant and subsequently developed erythema, facial flushing, and hypotension. Which drug is most likely responsible for these symptoms?

• A. Cisatracurium
• B. Atracurium
• C. Rocuronium
• D. Vecuronium

Hint:

Atracurium can cause histamine release, leading to flushing, erythema and hypotension.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The patient displays signs of histamine release: flushing, redness, and a drop in blood pressure.
We must identify which non-depolarizing muscle relaxant is classically associated with direct mast cell degranulation and histamine release.
Step 2: Detailed Explanation:

Histamine Release in Anesthesia: Several anesthetic drugs can cause a non-immunologic (direct) release of histamine from mast cells. This typically presents as transient flushing, tachycardia, and hypotension.

High-Risk Muscle Relaxants: Among the neuromuscular blockers, the benzylisoquinolinium group has the highest propensity for this. Atracurium and mivacurium are the primary culprits.

Low-Risk Muscle Relaxants:

Cisatracurium: Although it is an isomer of atracurium, it is highly potent and is administered in smaller doses that do not trigger significant histamine release.

Aminosteroids (Rocuronium/Vecuronium): These drugs have a different chemical structure and are not typically associated with spontaneous histamine release.


Clinical Significance of Atracurium: While atracurium is useful due to its organ-independent (Hofmann) elimination, its histamine-releasing potential means it should be used with caution in asthmatics or hemodynamically unstable patients.

Comparing Options: Atracurium is the classic answer for drug-induced flushing and hypotension in this category of drugs.

Step 3: Final Answer:
Atracurium is well-known for causing dose-related direct histamine release, leading to flushing and hypotension.