[Prolonged neuromuscular block after mivacurium injection]

Area of Science:

• Anesthesiology
• Pharmacology
• Biochemistry

Background:

• Mivacurium is a short-acting, non-depolarizing neuromuscular blocker metabolized by plasma cholinesterase.
• Reduced plasma cholinesterase activity can prolong the duration of action for mivacurium.
• Cholinesterase deficiency is an important consideration in patients receiving neuromuscular blocking agents.

Observation:

• A 69-year-old female with an unrecognized cholinesterase deficiency received intravenous mivacurium.
• The patient underwent a lumbar sympathectomy for lower limb arteriopathy.
• Prolonged neuromuscular blockade lasting 6 hours was observed post-administration.

Findings:

• Plasma cholinesterase concentrations were significantly low (540 and 610 UI.L-1).
• A low dibucaine number (16%) indicated a likely homozygous enzymatic deficiency.
• The prolonged block necessitated continued mechanical ventilation and sedation.

Implications:

• This case underscores the critical need for screening or awareness of cholinesterase deficiency before administering mivacurium.
• Anesthesiologists must be prepared for extended neuromuscular blockade in susceptible patients.
• Understanding enzymatic variations is crucial for optimizing patient safety and anesthetic management.