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.