Myasthenia gravis (MG) is an autoimmune disease that is characterized by muscle weakness and fatigue. The role of the thymus in MG has been suggested by the evidence that 10% to 15% of patients present with a thymoma and at least 60% with thymus hyperplasia or dysplasia.Beneficial effects of thymectomy in patients with MG have been described in 40% to 90%.Few studies have looked at the incidence of reintubation (not just within 24 hours after extubation), the factors associated with reintubation, and patient outcome.

Premature extubation may lead to hypercarbia, hypoxemia, pulmonary hypertension, right heart failure, and myocardial ischemia. Additionally, it subjects the patient to the physical risks of reintubation, including esophageal intubation, laryngeal trauma, and pulmonary aspiration. The purpose of the present study was to determine the incidence of reintubation, the variables associated with reintubation, and patient outcome

Inclusion was based on the availability of all the following possible predictive pre-operative variables: age, gender, weight, height, body mass index, diabetes, creatinine, duration of MG, severity of MG (based on Osserman's classification), pathological type of MG, history of myasthenic crisis, dose of pyridostigmine, use of a steroid hormone, and use of an immunosuppressant.operative variables: postoperative pulmonary infection, total duration of hospital stay, duration of ICU stay, and duration of postoperative hospital stay. Variables were collected by research assistants and maintained in a computer database.

Inclusion Criteria:

• younger than 75 years
• absence of heart failure as the primary indication for mechanical ventilation •Acute Physiology and Chronic Health Evaluation (APACHE) II score less than 12 points on day of extubation
• body mass index less than 30

Exclusion Criteria:

•preoperative moderate-to-severe chronic obstructive pulmonary disease

patients with myasthenia gravis undergoing thymectomy