A patient with myasthenia gravis is scheduled for elective surgery under general anaesthesia requiring muscle relaxation. The anaesthetist plans to use a non-depolarising neuromuscular blocking agent. Which of the following best describes the expected response of this patient to a standard intubating dose of vecuronium?
- A Increased sensitivity, requiring approximately 50 percent of standard dose ✓
- B Normal sensitivity, standard dosing appropriate
- C Resistance, requiring approximately double the standard dose
- D Paradoxical excitation and rigidity
Correct answer: A. Increased sensitivity, requiring approximately 50 percent of standard dose
Explanation
Myasthenia gravis is characterised by a reduced number of functional postsynaptic acetylcholine receptors at the neuromuscular junction. Non-depolarising agents compete for these receptors, so patients with MG are markedly sensitive to them. Standard doses of vecuronium would produce profound and prolonged blockade. The dose should be reduced to approximately one-third to one-half of the normal dose, with careful monitoring using a peripheral nerve stimulator.
Reference: Stoelting's Anaesthesia and Co-existing Disease, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.