Episode 38: Breathing beyond the block: Myasthenia gravis feat. dr. shorok hassan, dr. danielle langan, and emily roff, oms-iv
Takeaways:
Myasthenia gravis is an autoimmune disease affecting acetylcholine receptors on skeletal muscle. It causes fatigable skeletal muscle weakness. Myasthenic crisis is a life-threatening condition where the respiratory muscles are involved, leading to respiratory failure and often to intubation.
Cholinergic crisis is often on the differential diagnosis list for myasthenic crisis. It’s caused by increased acetylcholine, often due to excess acetylcholinesterase inhibition. It causes fasciculation of skeletal muscles, as well as parasympathetic symptoms like bradycardia, miosis, and “wet and drippy” symptoms (diaphoresis, vomiting, diarrhea etc).
The decision to intubate these patients is ultimately a clinical one. If they are in respiratory distress, intubate!
When you go to intubate these patients, do NOT reach for succinylcholine! Myasthenia gravis patients are often resistant to it at the normal doses. Reach for the non-depolarizing rocuronium instead, and cut the usual dose in half. A full dose will prolong the paralytic effects, so make sure you have some sugammadex in case you need to reverse it. Know what you’re getting into with these medications so you can make the best choice!
VC and NIF values:
Normal VC: 50-60 mL/kg
Normal NIF: more negative than -60 cm H2O
-60 to -30 cm H2O indicates mild weakness, and 0 to -30 indicates severe weakness.
Medications that can trigger myasthenic crisis:
See attached image below.
Resources:
Narayanaswami P, Sanders DB, Wolfe G, et al. International Consensus Guidance for Management of Myasthenia Gravis. Neurology. 2021;96(3):114-122. doi:10.1212/WNL.0000000000011124
Nickson C. Myasthenia Gravis. Life in the Fast Lane • LITFL. January 5, 2019. Accessed January 16, 2026. https://litfl.com/myasthenia-gravis/
Farkas J. Myasthenia gravis & myasthenic crisis. EMCrit Project. Accessed January 16, 2026. https://emcrit.org/ibcc/myasthenia/
Bird SJ, Levine JM. Myasthenic crisis - UpToDate. UpToDate. July 21, 2025. Accessed January 16, 2026. https://www-uptodate-com.nyit.idm.oclc.org/contents/myasthenic-crisis?search=myasthenic%20crisis&source=search_result&selectedTitle=1~31&usage_type=default&display_rank=1
Hager HH, Patel P, Burns B. Succinylcholine Chloride. In: StatPearls. StatPearls Publishing; 2025. Accessed January 16, 2026. http://www.ncbi.nlm.nih.gov/books/NBK499984/
David S, Sharma S. Vital Capacity. In: StatPearls. StatPearls Publishing; 2025. Accessed January 16, 2026. http://www.ncbi.nlm.nih.gov/books/NBK541099/
Caro D. Neuromuscular blocking agents (NMBAs) for rapid sequence intubation in adults for emergency medicine and critical care - UpToDate. UpToDate. Accessed January 19, 2026. https://www-uptodate-com.nyit.idm.oclc.org/contents/neuromuscular-blocking-agents-nmbas-for-rapid-sequence-intubation-in-adults-for-emergency-medicine-and-critical-care?sectionName=NMBAs%20FOR%20MYASTHENIA%20GRAVIS&search=myasthenic%20crisis&topicRef=5125&anchor=H21936012&source=see_link#H21936012
