Anesthesia and Postoperative Respiratory Compromise Following Major Lower Extremity Surgery: Implications for Combat Casualties

Abstract

Care of military casualties requires not only assessment of patient, injury, and setting, but also the consequences of care decisions on other organ systems. In contemporary conflicts, pelviperineal and lower extremity trauma are common injuries, yet the optimal perioperative anesthetic and analgesic care remains unclear. Residual anesthesia and opioids can cause respiratory depression, specifically postoperative respiratory depression and opioid-induced respiratory depression. This observational study quantified and compared the incidences of respiratory depression following general anesthesia (GA) and spinal anesthesia (SA) for lower extremity surgery. Respiratory data were collected from 173 patients receiving either GA (n = 43) or SA (n = 130) via a bioimpedance-based respiratory volume monitor. Patients were further subdivided by postoperative opioid administration. The overall incidence of respiratory depression was significantly higher in the SA group (48/130 vs. 6/43, p = 0.004). These findings suggest that, while SA may be considered the safer alternative, it may in fact introduce confounding factors, which increase the risk of respiratory depression. Ensuring adequate respiratory status is particularly critical for the military population, as combat casualties are often monitored in understaffed environments following surgery. Using an SA strategy instead of GA may not prevent postoperative respiratory depression, and respiratory volume monitor monitoring may be useful to optimize care.