What is the initial emergency department (ED) treatment for myasthenia gravis?

Updated: Sep 20, 2018
  • Author: William D Goldenberg, MD; Chief Editor: Andrew K Chang, MD, MS  more...
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Patients with myasthenia gravis who are in respiratory distress may be experiencing a myasthenic crisis or a cholinergic crisis. Before these possibilities can be differentiated, ensuring adequate ventilation and oxygenation is important. Patients with myasthenic crisis can develop apnea very suddenly, and they must be observed closely. Evidence of respiratory failure may be noted through ABG determination, pulmonary function tests, or pulse oximetry.

Airway maneuvers

Open the airway by suctioning secretions after positioning the jaw and tongue. Administer high-flow oxygen, and measure oxygen saturation by pulse oximetry. If respirations remain inadequate, ventilate by bag-valve mask while preparing to intubate. In the patient without an intact gag reflex, an oral airway may be placed.

Endotracheal intubation

Rapid sequence intubation should be modified, because depolarizing paralytic agents (eg, succinylcholine) have less predictable results in patients with myasthenia gravis. The relative lack of ACh receptors makes these patients relatively resistant to succinylcholine; therefore, higher doses must be used to induce paralysis. Once paralysis is achieved, it may be prolonged. [9]

A rapid-onset, nondepolarizing agent (ie, rocuronium, vecuronium) is the preferred paralytic agent for these patients. Although nondepolarizing agents delay the onset of paralysis, compared with succinylcholine, these medications do not result in unwanted prolonged paralysis. Following paralysis, intubation is accomplished as usual. ABG sampling guides ventilator settings.

Preliminary studies suggest that bilevel positive airway pressure (BiPAP) can prevent intubation in patients with myasthenic crisis without overt hypercapnia and should be considered in the patient who can be closely monitored. [9, 14] Hypercapnia present at the time of BiPAP initiation can predict failure and the need to proceed to endotracheal intubation. [15, 6]

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