Myasthenia gravis is an autoimmune disease of the neuromuscular junction, most commonly due to antibodies attacking acetylcholine receptors in the postsynaptic membrane. Up to 30% of patients with myasthenia gravis will experience a myasthenic crisis during their disease course. If rapid sequence intubation is indicated, the unique characteristics of this patient population must be considered in the event use of a paralytic is necessary. All paralytic agents can be expected to last significantly longer, and an unpredictable response may be seen with depolarizing agents - therefore non-depolarizing agents are preferred in this population.

Non-Depolarizing Agents (Rocuronium, Vecuronium)

• MG patients have increased sensitivity to non-depolarizing agents and require lower doses than typically used
• It is reasonable to dose non-depolarizing agents at one-half the standard dose used. For example, rocuronium would be dosed at 0.5-0.6 mg/kg instead of the standard 1-1.2 mg/kg

Depolarizing Agents (Succinylcholine)

• MG patients have decreased expression of normal acetylcholine receptors which are required for depolarizing agents to work effectively and require higher doses than typically used
• Succinylcholine is typically dosed at 1.5-2.0 mg/kg (roughly double the dose used in other patient populations)

 

References

Roper J, Fleming ME, Long B, Koyfman A. Myasthenia Gravis and Crisis: Evaluation and Management in the Emergency Department. J Emerg Med. 2017;53(6):843-853.

 

Abel, Mark, and James B Eisenkraft. “Anesthetic implications of myasthenia gravis.” The Mount Sinai journal of medicine, New York vol. 69,1-2 (2002): 31-7.