Spontaneous ventilation thoracoscopic thymectomy without muscle relaxant for myasthenia gravis: Comparison with "standard" thoracoscopic thymectomy

Abstract

Objectives: Myasthenia gravis (MG) benefits from thymectomy. However, its unpredictable response to muscle relaxants and volatile anesthetic agents may result in muscle weakness and subsequently in postoperative myasthenic crisis. The aim of this study was to determine the surgical outcomes after spontaneous ventilation compared with conventional intubated video-assisted thoracoscopic thymectomy (spontaneous-ventilation video-assisted thoracic thymectomy [SV-VATT] vs intubated video-assisted thoracic thymectomy) in patients with MG.

Methods: Data from all minimally invasive thymectomy procedures performed at our institute between January 2009 and June 2016 were collected. Patient characteristics, perioperative results, and treatment outcomes between SV-VATT (group 1) and the intubated video-assisted thoracic thymectomy (group 2) groups were compared. Furthermore, a propensity score-matching analysis was generated to control for selection bias due to nonrandom group assignment in a 1:1 manner.

Results: Thirty-six patients were included in group 1 and 68 in group 2. Matching of patients according to propensity score resulted in a cohort that consisted of 27 patients in both groups. Patients had similar clinical characteristics in both groups. Operating time (P = .07) and lowest pulse oxygen saturation (P = .09) between the procedures were comparable after matching, but peak CO₂ level at the end of expiration was significantly greater in group 1 both before and after matching (P < .01). Moreover, the incidence of postoperative myasthenic crisis and postoperative prolonged tracheal intubation was lower in group 1. The postoperative pain visual analog scale score (P < .01) and the length of hospital stay (P = .03) were shorter in group 1.

Conclusions: SV-VATT is a feasible procedure in patients with MG. It might be beneficial by reducing postoperative myasthenic crisis and postoperative prolonged tracheal intubation. Further prospective research is needed.

Keywords: myasthenia gravis; spontaneous ventilation; video-assisted thoracoscopic thymectomy.