Incidence of intraoperative hypotension in acute traumatic spinal cord injury and associated factors

OBJECTIVE The importance of maintaining mean arterial pressure (MAP) > 85 mm Hg for patients with acute spinal cord injury (SCI) is well documented, because systemic hypotension greatly increases the risk of secondary SCI. Current literature focuses on the ICU setting; however, there is a paucity of data describing the changes in MAP in the operating room (OR). In the present study, the authors investigated the incidence of intraoperative hypotension for patients with acute traumatic SCI as well as any associated factors that may have impacted these findings. METHODS This retrospective study was performed at a level 1 trauma center from 2015 to 2016. All patients with American Spinal Injury Association (ASIA) score A-D acute traumatic SCIs from C1 to L1 were identified. Those included underwent spinal instrumentation and/or laminectomy decompression. Associated factors investigated include the following: age, body mass index, trauma mechanism of injury, Injury Severity Score, level of SCI, ASIA score, hospital day of surgery, total OR time, need for laminectomy decompression, use of spinal fixation, surgical positioning, blood loss, use of blood products, length of hospital stay, length of ICU stay, and discharge disposition. Intraoperative minuteby-minute MAP recordings were used to determine time spent in various MAP ranges. RESULTS Thirty-two patients underwent a total of 33 operations. Relative to the total OR time, patients spent an average of 51.9% of their cumulative time with an MAP < 85 mm Hg. Furthermore, 100% of the study population recorded at least one MAP measurement < 85 mm Hg. These hypotensive episodes lasted a mean of 103 cumulative minutes per operative case. Analysis of associated factors demonstrated that fall mechanisms of injury led to a statistically significant increase in intraoperative hypotension compared to motor vehicle collisions/motorcycle collisions (p = 0.033). There were no significant differences in MAP recordings when analyzed according to all other associated factors studied. CONCLUSIONS This is the first study reporting the incidence of intraoperative hypotension for patients with acute traumatic SCIs, and the results demonstrated higher proportions of relative hypotension than previously reported in the ICU setting. Furthermore, the authors identified that every patient experienced at least one MAP below the target value, which was much greater than the initial hypothesis of 50%. Given the findings of this study, adherence to the MAP protocol intraoperatively needs to be improved to minimize the risk of secondary SCI and associated deleterious neurological outcomes.