Effect of prethymectomy plasma exchange on postoperative respiratory function in myasthenia gravis.

The effect of prethymectomy plasma exchange on postoperative mechanical ventilation requirement and length of stay in the intensive care unit were studied retrospectively in 37 patients with myasthenia gravis. We found a significantly decreased time on mechanical ventilation (mean 1.02 +/- 0.40 versus 3.43 +/- 0.60 days) and a shorter stay in the intensive care unit (mean 3.09 +/- 0.99 versus 5.15 +/- 0.66 days) for 11 patients with respiratory weakness who were treated with preoperative plasma exchange compared with 26 patients who did not receive plasma exchange. Patients with respiratory weakness who received prethymectomy plasma exchange required less time on mechanical ventilation (mean 1.02 +/- 0.40 versus 2.73 +/- 0.88 days) and a shorter stay in the intensive care unit (mean 3.09 +/- 0.99 versus 4.46 +/- 1.08 days) than those patients without respiratory weakness who did not receive plasma exchange. Eleven patients met the criteria for plasma exchange but did not receive it. They required significantly more time on mechanical ventilation (mean 4.43 +/- 0.94 versus 1.02 +/- 0.40 days) and in the intensive care unit (mean 6.09 +/- 0.86 versus 3.09 +/- 0.99 days) than patients who received plasma exchange. Our results indicate that patients with severe forms of myasthenia gravis treated with prethymectomy plasma exchange require less mechanical ventilation and less time in the intensive care unit postoperatively.