Association of intraoperative cerebral and muscular tissue oxygen saturation with postoperative complications and length of hospital stay after major spine surgery: an observational study.

BACKGROUND.: Compromised tissue oxygenation is one of the root causes of dysfunction of various organs and postoperative complications. Oxygenation of different tissue beds may follow different patterns of change during physiological derangement. METHODS.: Patients undergoing elective major posterior spine surgery participated in this prospective observational study. Cerebral tissue oxygen saturation (SctO 2 ) was monitored on the upper forehead and muscular tissue oxygen saturation (SmtO 2 ) on the lower leg. The associations of various oxygenation indices with postoperative composite complications and length of hospital stay (LOH) were investigated. RESULTS.: The number of composite complications per patient was 3  (2) while the LOH was 6 (3) days (n = 102). Multiple SmtO 2 indices (maximum, minimum, mean, median, and area under curve (AUC)) were associated with composite complications (univariate analysis, P  < 0.05). No SctO 2 indices were associated with complications. Multiple SmtO 2 indices (maximum, mean, median, and AUC) showed differences ( P  < 0.05) between patients with composite complications ≤3 and >3, respectively. SmtO 2 standard deviation, AUC, and AUC weighted, and SctO 2 standard deviation, were associated with LOH (univariate analysis, P  < 0.05). Two SmtO 2 indices (AUC and AUC weighted), showed differences ( P  < 0.05) between the patients with an LOH ≤6 and >6 days, respectively. SmtO 2 , but not SctO 2 , indices improved the adjusted R 2 for composite complications (+54.0%, P  = 0.0001) and LOH (+19.0%, P  = 0.02) based on multiple linear models. CONCLUSIONS.: Muscular tissue oxygenation has a stronger association with postoperative complications and length of hospital stay than cerebral tissue oxygenation after major spine surgery.