Changes in Respiratory Condition After Thymectomy for Patients with Myasthenia Gravis

Background: Anesthesia without muscle relaxants has been reported to be effective for early extubation after thymectomy, but postoperative respiratory status of the patients has not been studied intensively.

Methods: Fifty-two consecutive patients undergoing thymectomies for myasthenia gravis (MG) were evaluated.

Results: Forty-two (81%) of the 52 patients were extubated in the operating room, and 49 (94%) patients were extubated within 24 hours. However, 6 (12%) patients required subsequent reintubation for respiratory support. There was a sudden increase in the respiratory rate (RR) and PaCO(2). The mean value of the increase in PaCO(2) at the time of reintubation was 23 mmHg (12-58 mmHg). The mean value of the increase in RR above the preoperative level at the time of reintubation was 16/min (7-30/min). In univariate analysis, vital capacity (VC), %VC, the preoperative pyridostigmine dose and the duration of surgery correlated with reintubation, but with multivariate analyses, the pyridostigmine dose was the only significant factor related to reintubation.

Conclusion: The patients who received at least or more than 240 mg of pyridostigmine should be monitored carefully after tracheal extubation.