Bjorshol CA, Sunde K, Myklebust H, et al. Decay in chest compression quality due to fatigue is rare during prolonged advanced life support in a manikin model. Scand J Trauma Resusc Emerg Med 19(1): 46, Aug 9, 2011.
The aim of this study was to measure chest compression decay during simulated advanced life support (ALS) in a cardiac arrest manikin model. Methods—19 paramedic teams, each consisting of three paramedics, performed ALS for 12 minutes with the same paramedic providing all chest compressions. The patient was a resuscitation manikin found in ventricular fibrillation (VF). The first shock terminated the VF, and the patient remained in pulseless electrical activity (PEA) throughout the scenario. Average chest compression depth and rate was measured each minute for 12 minutes and divided into three groups based on chest compression quality: good (compression depth greater than or equal to 40 mm, compression rate 100–120/minute for each minute of CPR), bad (initial compression depth less than 40 mm, initial compression rate less than 100 or greater than 120/minute) or decay (change from good to bad during the 12 minutes). Changes in no-flow ratio (NFR, defined as the time without chest compressions divided by the total time of the ALS scenario) over time was also measured.
Results—Based on compression depth, 5 (26%), 9 (47%) and 5 (26%) were good, bad and with decay, respectively. Only one paramedic experienced decay within the first two minutes. Based on compression rate, 6 (32%), 6 (32%) and 7 (37%) were good, bad and with decay, respectively. NFR was 22% in both the 1–3 and 4–6 minute periods, respectively, but decreased to 14% in the 7–9 minute period (P=0.002) and to 10% in the 10–12 minute period (P < 0.001). Conclusions—In this simulated cardiac arrest manikin study, only half of the providers achieved guideline recommended compression depth during prolonged ALS. Large inter-individual differences in chest compression quality were already present from the initiation of CPR. Chest compression decay and thereby fatigue within the first two minutes was rare.
We all know the value of high-quality CPR in the treatment of patients in cardiac arrest. Components of optimal CPR include correct depth and rate, full chest recoil, and minimal interruptions. To combat fatigue, CPR guidelines recommend changing the person performing chest compressions every two minutes. However, the process of switching compressors introduces interruptions that have been shown to substantially increase the hands-off time (no-flow ratio), so this is better avoided if possible.
This study involved experienced (average 8.5 years) paramedics. The ones who performed excellent CPR continued to do so—even after 12 minutes. Decline in performance was only seen in those paramedics who started off with inadequate (slow and/or shallow) compressions. Further research will establish how to increase CPR proficiency and, once that is achieved, what constitutes a reasonable change-over time. For now, this study suggests that an EMS system initiative to improving training—so that everyone who might do CPR can perform optimal chest compressions—may be more effective than switching compressors every two minutes.
Angelo Salvucci, Jr., MD, FACEP, is medical director for the Santa Barbara County and Ventura County (CA) EMS agencies and a member of EMS World's editorial advisory board.