Introduction: Aeromedical helicopters and fixed wing aircraft are used across Canada to transfer patients to definitive care. Given height limitation in aeromedical transport, CPR performance can be affected. An adapted manual compression technique has been proposed by H. Koch (pron. Cook) that uses the elbow to compress the sternum rather than the conventional hand. This preliminary study evaluated the quality of Koch compressions versus conventional bimanual compressions. Methods: Paramedics (5), registered nurses (3) and a physician (1) were recruited. Each participant performed a 2 minute cycle of each technique, were randomized to determine which technique was performed first, and rested 5 minutes between compression cycles. A Resusci Anne SkillReporter manikin atop a stretcher in a BK117 helicopter was used. The compressors performed without feedback or prompting. Outcomes include compression rate, depth, recoil, and fatigue. Results: The mean conventional compression rate was (bpm) 118 +/− 13 versus 111 +/− 10 in the Koch scenario (p=0.02) (target 100 to 120). Mean conventional compression depth (mm) was 44 +/− 9 versus 49 +/− 7 in the Koch scenario (p=0.01) (target 50 to 60). The mean percentage of compressions with complete release in the conventional scenario was 86 +/− 20 versus 84 +/− 22 in the Koch scenario (p=0.9) (target 100%). Using a Modified Borg Scale of 1 to 10, mean provider fatigue after conventional CPR was 7 (+/− 1.6) versus 3 (+/− 1.2) using Koch technique (p<0.001). On average, Koch technique improved the percentage of compressions at target rate by 26%, the percentage at correct depth by 9%, overall compression quality score by 13% and were more less fatiguing. Conclusion: Using an elbow in a height-restricted environment improved compression depth and reduced provider fatigue. From our limited data, Koch compressions appear to improve compression quality. Further study and external validation are required.