[Prediction of the need for postoperative mechanical ventilation in myasthenia gravis patients]

The prediction of the need for postoperative mechanical ventilation in 23 myasthenia gravis patients, who had undergone thymectomy from January 1983 to December 1989, was evaluated. Five patients who had needed postoperative mechanical ventilation over 24 hours were compared with the patients in whom the tracheal tubes had been uneventfully extubated within 24 hours postoperatively. In this study, 47.8%, 78.3%, 91.3% of the patients were correctly predicted using the scoring systems proposed by Leventhal et al., Makii et al. and Kimura et al., respectively. The product of %VC by FEV1.0% was proposed in this study for the prediction of the need of postoperative mechanical ventilation in patients with myasthenia gravis. If the product is less than 8,300, the patient is expected to need postoperative mechanical ventilation. Nineteen patients out of 23 cases (82.6%) were predicted correctly by this value. Only one patient, who had been predicted to be in no need, was actually ventilated for 3 days. In conclusion, the product of %VC by FEV1.0% is a simple and practical method of predicting whether a patient with myasthenia gravis undergoing thymectomy requires postoperative mechanical ventilation or not.