A new method for the performance of external chest compressions during hypogravity simulation

Area of Science:

• Space Medicine
• Emergency Medicine
• Physiology

Background:

• Current UK resuscitation guidelines recommend external chest compression (ECC) depths of 50-60 mm.
• Achieving adequate ECC depth in hypogravity presents a challenge for cardiopulmonary resuscitation (CPR).
• The novel 'Mackaill-Russomano' (MR CPR) method was developed to address this challenge.

Purpose of the Study:

• To evaluate the effectiveness of the MR CPR method in simulating hypogravity environments.
• To assess ECC depth and rate adherence to 2015 UK guidelines under simulated lunar and Martian gravity.
• To compare the MR CPR method with standard CPR techniques in varying gravitational conditions.

Main Methods:

• Ten participants performed sets of 30 ECCs under controlled conditions, including 1G (control) and simulated hypogravity (0.38Gz and 0.17Gz).
• Simulations utilized a body suspension device with counterweights and included conditions with and without braces, and the MR CPR method.
• The MR CPR method involved straddling a mannequin for stabilization.
• Measurements included ECC depth, rate, arm flexion angle, and heart rate.

Main Results:

• The MR CPR method achieved mean ECC depths of 54.1 mm (with braces) and 50.5 mm (without braces) at 0.38Gz, meeting guideline targets.
• At 0.17Gz, ECC depths were below the 50 mm guideline (47.5 mm with braces, 47.4 mm without) using the MR CPR method.
• In the terrestrial position, ECCs were more effective without braces (49.4 mm at 0.38Gz) compared to with braces (48.5 mm at 0.38Gz).
• Arm flexion increased significantly, while heart rate remained stable compared to the control.

Conclusions:

• The MR CPR method successfully achieved 2015 UK resuscitation guideline ECC depths at 0.38Gz, with no significant difference between using braces or not.
• ECC effectiveness in the terrestrial position was better without braces.
• Achieving target ECC depth was not possible at 0.17Gz due to the significant reduction in effective body weight, highlighting limitations in lower gravity environments.