Estimation of Chest Compression Rate and Detection of Hands-off Intervals During Resuscitation With Automated External Defibrillators

Quality of chest compressions (CCs) is key for patient's survival to cardiac arrest. Incorporating real-time feedback on CC rate in automated external defibrillators (AEDs) could enhance CC quality. The aim of the study was to design a method for detecting CC pauses and computing CC rate using the transthoracic impedance (TI) signal acquired from the AED defibrillation pads. We collected 35 AED recordings from a database property of Emergentziak-Osakidetza (Basque Country, Spain). Using the ECG and TI signals, a CC pause was annotated when CCs were interrupted for more than 3 s. The algorithm estimates the CC rate from the autocorrelation of 2-s consecutive TI intervals. The algorithm reported a sensitivity (Se) and a positive predictive value (PPV) in the detection of CC pauses of 97.64%/92.48%. Reliable CC rates were obtained with a Se/PPV of 99.03%/98.61%. Unreliable CC rates were reported only in 0.9% of the cases. A method based on the autocorrelation of the TI signal allows reliable detection of CC pauses and estimation of CC rates, enhancing current AED functionality.