The intraoperative administration of ketamine to burned U.S. service members does not increase the incidence of post-traumatic stress disorder.

Aim: Patients with severe burns typically undergo multiple surgeries, and ketamine is often used as part of the multimodal anesthetic regimen during such surgeries. The anesthetic ketamine is an N-methyl-D-aspartate receptor antagonist that also provides analgesia at subanesthetic doses, but the psychoactive side effects of ketamine have caused concern about its potential psychological effects on a combat-wounded population. Post-traumatic stress disorder (PTSD) affects approximately 30% of burned U.S. service members injured in Operation Iraqi Freedom/Operation Enduring Freedom. A preliminary analysis by our research group reported that patients who received perioperative ketamine had a significantly lower prevalence of PTSD than those injured service members who did not receive ketamine. We have now expanded this research to examine the relationship between ketamine and PTSD development in a much larger population. Methods: A retrospective analysis on data from service members being treated for burns at the San Antonio Military Medical Center was conducted. Collected data included drugs received, injury severity score (ISS), total body surface area (TBSA) burned, length of hospital stay (LOS), number of intensive care unit days, number of surgeries, and PTSD Checklist-Military (PCL-M) scores and administration dates. Subjects were grouped based on intraoperative receipt of ketamine, and the groups were compared. The groups were binary for ketamine (yes or no), and dose of ketamine administered was not included in data analyses. Propensity score matching based on ISS and TBSA was performed to control for individual differences in burn severity. Results: Two hundred eighty-nine burned U.S. service members received the PCL-M at least 30 days after injury. Of these subjects, 189 received intraoperative ketamine, and 100 did not. Despite significantly greater injuries, as evidenced by significantly higher TBSA burned and ISS (p < 0.01), patients who received ketamine did not screen positive for PTSD at a different rate than those patients who did not (24% vs. 26.98%, p = 0.582). Patients receiving intraoperative ketamine also underwent a significantly greater number of surgeries, spent more time in the hospital, spent more days in the ICU, and received more morphine equivalent units (p < 0.0001). Propensity score matching based on ISS and TBSA resulted in a total subject number of 130. In the matched samples, subjects who received ketamine still underwent significantly more surgeries and experienced longer hospital stays (p < 0.0001). Again, there was no statistically significant difference in the incidence of a positive screen for PTSD based upon the receipt of ketamine (28% vs. 26.15%, p = 0.843). Conclusions: Ketamine is often used in burn patients to reduce opioid usage and decrease the hemodynamic and respiratory side effects. Although this study does not show a benefit of ketamine on PTSD development that was identified in previous work with a smaller sample number, it does support the conclusion that ketamine does not increase PTSD development in burned service members.