Prehospital and en route analgesic use in the combat setting: a prospectively designed, multicenter, observational study.

BACKGROUND Combat injuries result in acute, severe pain. Early use of analgesia after injury is known to be beneficial. Studies on prehospital analgesia in combat are limited and no prospectively designed study has reported the use of analgesics in the prehospital and en route care setting. Our objective was to describe the current use of prehospital analgesia in the combat setting. METHODS This prospectively designed, multicenter, observational, prehospital combat study was undertaken at medical treatment facilities (MTF) in Afghanistan between October 2012 and September 2013. It formed part of a larger study aimed at describing the use of lifesaving interventions in combat. On arrival at the MTF, trained on-site investigators enrolled eligible patients and completed standardized data capture forms, which included the name, dose, and route of administration of all prehospital analgesics, and the type of provider who administered the drug. Physiological data were retrospectively ascribed as soon as practicable. The study was prospectively approved by the Brooke Army Medical Center institutional review board. RESULTS Data were collected on 228 patients, with 305 analgesia administrations recorded. The predominant mechanism of injury was blast (50%), followed by penetrating (41%), and blunt (9%). The most common analgesic used was ketamine, followed by morphine. A combination of analgesics was given to 29% of patients; the most common combination was ketamine and morphine. Intravenous delivery was the most commonly used route (55%). Patients transported by the UK Medical Emergency Response Team (MERT) or U.S. Air Medical Evacuation (Dust-off) team were more likely to receive ketamine than those evacuated by U.S. Pararescue Jumpers (Pedro). Patients transported by Medical Emergency Response Team or Pedro were more likely to receive more than 1 drug. Patients who received only ketamine had a higher pulse rate (p<0.005) and lower systolic blood pressure (p=0.01) than other groups, and patients that received hydromorphone had a lower respiratory rate (p=0.04). CONCLUSIONS In our prospectively designed, multicenter, observational, prehospital combat study, ketamine was the most commonly used analgesic drug. The most frequently observed combination of drugs was ketamine and morphine. The intravenous route was used for 55% of drug administrations.