Objective: To determine the incidence and risk factors for postoperative respiratory complications (PORCs) in myasthenia gravis (MG) patients.
Material and Method: Patients who underwent thymectomy at Siriraj Hospital between 2010 and 2014 were retrospectively analyzed. PORCs were defined as 1 delayed extubation (i.e., failed extubationin the operating theater, planned remain intubation); 2 ventilator support requirement (re-intubation or non-invasive positive pressure ventilation) within 24 hours after extubation. Patients’ characteristics and perioperative data were recorded and analyzed.
Results: Among 134 MG patients, 9.7% developed PORCs. As for risk of PORCs, univariate analysis identified preoperative pyridostigmine consumption (OR 3.82, 95% CI 1.12 to 13.07, p = 0.03), preoperative plasmapheresis (OR 10.82, 95% CI 1.39 to 84.46, p = 0.02), and prolonged operation (OR 1.02, 95% CI 1.00 to 1.03, p = 0.03) were risk factors for PORCs. Multivariate analysis identified preoperative pyridostigmine consumption (OR 6.37, 95% CI 1.32 to 30.88, p = 0.02) and Osserman class III (OR 5.44, 95% CI 1.02 to 24.63, p = 0.04) as predictors of PORCs.
Conclusion: MG patients who receive preoperative pyridostigmine alone and those at Osserman class III should be especially monitored for respiratory complications after thymectomy.

Keywords: Myasthenia gravis, Thymectomy, Respiratory Complications, Risk factors