Abstract 261: Assessment of Area Duty Cycle in Manual Chest Compressions During Out-of-Hospital Cardiopulmonary Resuscitation

Abstract

Introduction: To be compliant with resuscitation guidelines, chest compressions (CCs) should be provided at a rate between 100 and 120 min -1 and a depth between 50 and 60mm during cardiopulmonary resuscitation (CPR). However, two manual CCs coincident in rate (the inverse of duration) and depth can show very different compression waveforms (left figure: the narrower CC depicted in blue suggests a higher impulse compression/decompression pattern). We hypothesized that area duty cycle (ADC) could characterize the narrowness of manual CCs. Objective: To assess the ADC of manual CCs during out-of-hospital CPR and its relationship with rate and depth. Methods: We collected electronic recordings containing compression signals from Philips HeartStart MRx monitor-defibrillators used in 30 patients during out-of-hospital CPR. ADC was defined as the ratio between the area under the compression curve (dashed area in the right figure) and the total area of the compression cycle with maximum depth (area of the red box). For each CC, we annotated the compression duration T c , the area under the depth curve A, and the maximum compression depth D. ADC was computed as 100·A/T c ·D (%). The linear relationship of ADC with compression rate and depth was assessed. Results: A total of 66,971 CCs were annotated. Medians (5 th -95 th percentiles) for compression rate, depth and ADC were 109.9 min -1 (93.8, 133), 46.5 mm (30.1, 61.7), and 41.9% (32.1, 49.5), respectively. ADC showed a very low correlation with rate and depth, favoring ADC’s independence. For every 10 min -1 increase in rate, ADC increased 0.16%. For every 10 mm increase in depth, ADC decreased 0.5%. Conclusions: ADC metric could be used for characterizing the narrowness of manual CCs, independently of depth and rate. This finding could contribute to improve understanding of manual CPR dynamics and their influence on patient’s outcome.