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Myasthenia gravis and postop ventilation

The requirement for post-op mechanical ventilation in myasthenia gravis patients is based on multiple factors including perioperative risk factors as well as pre-operative health. The following are factors described to be indicative of higher likelihood for post-op mechanical ventilation requirements following a thymectomy (1):

  • Duration of myasthenia gravis (>6 years)
  • Concomitant chronic lung disease
  • Large doses of pyridostigmine maintenance (>750mg/day)
  • Low vital capacity on PFTs (<2.9L)

More recently, additional factors have been thought to also increase chances of post-op mechanical ventilation, including (2):

  • Positivity for anti-acetylcholine antibodies
  • Low vital capacity (<2.9 L)
  • CT scan imaging showing a thymoma
  • Pre-op history of a prior myasthenic crisis

Interestingly, this study did not show any statistically significant effect of duration of myasthenia gravis or pre-op pyridostigmine dosage with regards to post-op ventilation requirements.


  1. S.R. Leventhal, F.K. Orkin, R.A. Hirsh. Prediction of the need for postoperative mechanical ventilation in myasthenia gravis. Anesthesiology, 53 (1980), pp. 26-30 PubMed Link
  2. Chigurupati, Keerthi, et al. “Criteria for Postoperative Mechanical Ventilation After Thymectomy in Patients With Myasthenia Gravis: A Retrospective Analysis.” Journal of Cardiothoracic and Vascular Anesthesia, vol. 32, no. 1, Feb. 2018, pp. 325–330. PubMed Link