González-Otero DM, Russell JK, Ruiz R, et al. - Researchers examined how the maximum velocities during compression and recoil phases are associated with compression depth and rate in manual cardiopulmonary resuscitation (CPR). Compression instances were determined in out-of-hospital cardiac arrest recordings using custom Matlab programs. The analysis revealed a high correlation of compression and recoil velocities (CV and RV) with compression depth and compression and recoil times, respectively. Total and effective compression and recoil durations were noted to have an inverse relation with the compression rate. RV values were similar among compressions; this was observed regardless of whether compressions were compliant with recommended depth and rate. Conversely, compressions having the same depth and rate, but presenting very distinct compression waveforms, differed in RV values.