Chest diameter measurement in pediatric patients for chest compression feedback calibration

Adequate compression depth is a main quality parameter during cardiopulmonary resuscitation (CPR). Current CPR feedback devices can guide adult target depth which is fixed between 5 and 6 cm. For pediatric patients, conversely, target depth should be one third of the antero-posterior diameter of the chest. The aim of this study was to develop an algorithm to estimate chest diameter in pediatric patients using accelerometers. Using a tri-axial accelerometer, we measured the accelerations generated when moving the sensor from the floor to five different heights that simulated chest diameter. Five volunteers generated two records each per height. A total of fifty records were acquired. Chest diameter was measured by discrete integration of the z-axis acceleration signal. Velocity signal was band-pass filtered before computing the displacement signal. Chest diameter was identified as the displacement value at the instant in which the movement finished. Median (P25, P75) unsigned absolute and relative errors were 0.9 cm (0.3, 1.9) and 9.2 % (2.5, 14.6), respectively. Error in estimation of pediatric target compression depth was below 6.5 mm in 75 % of the cases. The proposed algorithm could be used to calibrate target chest compression depth in CPR feedback devices to be adapted for pediatric patients