Abstract P172: Perceived Exertion and Physiological Responses During Performance of Continuous Chest Compressions
Background: Minimizing chest compression (CC) interruptions improves cardiac arrest outcomes; yet, it is possible that rescuers are not capable of performing nearly continuous CC. The goal of the present study was to determine the effects of reducing CC interruption on the degree of rescuer physical exertion and perceived effort.
Methods: Thirty subjects (20 BLS and 10 ALS trained individuals) participated in a randomized crossover simulation study to measure the physical exertion required to perform continuous CC on a mannequin using a defibrillator (ZOLL Medical) in the standard (STD) mode (AED or manual) compared to a new mode, CPR Ready Charge (CRC), designed to limit interruptions in CC. Subjects worked in pairs with one operating the defibrillator and the other performing CC. Rescuers switched roles after every 2 CC intervals (interval=2 min CC, analysis, and shock if necessary) for a total of 4 intervals of CC per subject. Subjects rested a minimum of 30 minutes before crossing over to the trial with the other mode. Heart rate was measured using pulse oximetry. After each trial, subjects rated their perceived exertion using the Borg Scale (6=no exertion; 20=maximal exertion) as well as perceived pain (0=min; 10=max) for each of the 4 intervals in which they performed CC.
Results: Although less pause time was observed with the CRC mode (22.2±9.2 sec CRC vs. 56.0±13.1 STD, p<0.0001), heart rate was similar for each of the 4 CC intervals with the CRC and STD modes (interval 1: 116±17 bpm CRC vs. 109±14 bpm STD, p=0.1; interval 2: 116±14 vs. 113±12, p=0.2; interval 3: 109±20 vs. 116±15, p=0.2; interval 4: 123±16 vs. 120±12, p=0.3). Subjects reported a similar perceived exertion at each of the 4 CC intervals when using the CRC vs. STD mode (interval 1: 8.6±2.0 CRC vs. 8.5±1.9 STD, p=0.9; interval 2: 10.3±2.2 vs. 9.8±2.1, p=0.3; interval 3: 11.2±2.0 vs. 11.1±2.1, p=0.7; interval 4: 12.7±2.3 vs. 12.5±2.3, p=0.4). Pain rating was also similar at each of the 4 time points (interval 1: 0.9±1.4 CRC vs. 1.0±1.1 STD, p=0.8; interval 2: 1.6±1.6 vs. 1.6±1.6, p=0.9; interval 3: 2.2±1.6 vs. 2.4±1.6, p=0.7; interval 4=3.5±2.0 vs. 3.5±2.2, p=0.97).
Conclusions: Subjects are able to perform nearly continuous CC for at least 4 minutes without excessive physical exertion or perceived effort.