Tehran University Medical Journal

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Background: Respiratory failure and crisis is one of major complications of thymectomy in myasthenia gravis patients. There are different medication regimes for preparing these patients for surgery and reducing post-operative side effects. The goal of this study is to compare respiratory complications of oral vs. Parenteral preoperative administration of anticholinesterase agents for thymectomy in myasthenia gravis patients.
Methods: This randomized controlled trial included 101 patients in class IIA or IIB of myasthenia gravis according to the Osserman classification system. The control group fasted for eight hours before surgery and oral anticholines-terase agents were replaced with parenteral ones. The case group also fasted for 8 hours before surgery, but pyridostigmine was continued at its usual dose until the time of operation and the last dose was given to patients with a small amount of water in the operating room on the operating bed.
Results: There was no statistically meaningful difference between the two groups in terms of age, sex and pathologic findings. In comparison, the mean hospital stay for the case group was 3.98 days and 6.34 for the control group (p value = 0.003). There were eight cases of respiratory crisis or failure (16%) in the control group but only 1 case (2%) was observed in case group (p value = 0.014). Only one patient in the case group required re-intubation after the surgery however, six patients in control group were re-intubated (p value = 0.053). Plasmapheresis was required for five patients in the control group and one patient in the case group (p value = 0.098). Tracheostomy was performed on two patients in the control group to accommodate prolonged intubation, but none of the case group required this procedure.
Conclusion: This study shows that continuing oral anticholinesterase agents up to the time of operation, with the last dose at the operative theater, lowers the incidence of postoperative myasthenia crisis and respiratory failure, need for plasmapheresis and shortens the hospital stay. This method may also decrease the need for re-intubation, mechanical ventilation and tracheostomy, thus decreasing the chance of death resulting from complications of the thymectomy.