Abstract 343: Chest Compression Compliance With Guidelines Declines Over the Course of Rescues

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.

Estimation of Die Release Force of mboxJIS-ADC12 Aluminum Alloy Die Castings Manufactured Through High-Pressure Die Casting via Computer Simulation

A method for the estimation of the die release force of die castings of JIS-ADC12 aluminum alloy manufactured through high-pressure die casting was examined. The die release force was evaluated by the strain in the axial direction of the extrusion pin when releasing the die castings. In this research, it was assumed that the factors that influenced the die release force were the thermal deformation of the die and die castings and the reaction layer of Al and Fe generated during the solidification process in the die. These factors in the resistance of the die release were evaluated by the friction coefficient. The die and die castings temperature in the die release process were simulated, and calculation results were mapped onto an FE model, and a coupled analysis of the thermal structure was performed. The calculated value of the mold release force was approximately the same as the actual value, and the friction coefficient was estimated to be approximately 0.5.