Introduction:
CPR guidelines recommend limits for rate and depth, and release (avoidance of leaning). Simultaneous compliance with all three recommendations is challenging, sustained compliance more so.
Hypothesis:
Compliance with rate, depth and release guidelines is limited, and will decline over the course of rescues.
Methods:
Acceleration and force signals were extracted from monitor/defibrillators equipped with CPR monitors in 248 adult cases of manual CPR during out-of-hospital resuscitations treated by Tualatin Valley Fire & Rescue (TVF&R, Tigard, OR) during 2016 and 2017. TVF&R personnel delivered continuous compression CPR with real-time feedback available for rate, depth and leaning. Depth was calculated from acceleration. Peak depth, release force, and rate were measured for each compression. Release with force exceeding 2.5 kg-f was counted as incomplete (leaning).
Results:
Cases included 1802 (1055-2683) (median, IQR) compressions (total 481,407 compressions). Compliance with all three recommendations was 25% initially, declining to 19% for the ends of the longest rescues (> 3000 compressions from 48 cases). Depth compliance and complete release varied relatively little (31-36%, 93-95% respectively) and irregularly over the course of resuscitation. Early, 45% of compressions were too shallow (< 50 mm), and 21% were too deep (> 60 mm). Depth exceptions shifted over the course of resuscitation (to 36%, 28% respectively). Rate compliance declined from 73% to 54%. Rates below 100 cpm were 9% initially, declining to 5%. Rates exceeding 120 cpm were 18% early on, but climbed to 41% towards the end of long resuscitations, accounting for most of the decline in compliance with guidelines.
Conclusions:
Compliance with all 3 recommendations for CPR compressions is challenging, and becomes more so as the chest changes in response to compressions. Most problematic is a steady increase in compression rates above 120 cpm.
Untangling superposed double layer and structural forces across confined nanoparticle suspensions
