Multivariate determinants of the need for postoperative ventilation in myasthenia gravis.

PURPOSE: Following transsternal thymectomy, up to 50% of patients may require postoperative ventilation. The aim of this study was to identify the variables most useful in predicting the myasthenic patient who needs postoperative mechanical ventilation.
METHODS: We applied multivariate discriminant analysis to preoperative physical, historical, laboratory and intraoperative data of 51 myasthenic patients who underwent transcervical-transsternal thymectomy to select those variables most useful in predicting the postoperative need for mechanical ventilation. The receiver operating characteristic (ROC) curve was also used to describe the discrimination abilities and to explore the trade-offs between sensitivity and specificity of the model.
RESULTS: Discriminant analysis identified seven risk factors that correlated with the need for postoperative ventilation: FVC, FEF25-75%, MEF50% and their percentages of the predicted values, as well as, sex. The model correctly predicted the actual ventilatory outcome in 88.2% of patients. The area under the ROC curve verified that our model correctly predicted the actual ventilatory outcome with a probability of 88.2%.
CONCLUSIONS: This model can be used for predicting the need for postoperative mechanical ventilation in myasthenia gravis patients.