Relation between chest compression rate and depth: the ENFONCE Study

Abstract

Introduction: Chest compressions are the cornerstone of cardiopulmonary resuscitation. The recent International Liaison Committee on Resuscitation guidelines recommend increasing the rate and the depth of chest compressions, to 100-120/min and 5-6 cm, based on theoretical arguments and observational studies. We hypothesized that an increased chest compressions rate could decrease chest compressions depth.

Methods: Operators were asked to perform continuous chest compressions on a mannequin. Chest compressions rate and depth were collected. The ratio of chest compressions compliance to the guidelines, that is rate 100-120/min and depth 5-6 cm, was calculated.

Results: In total 951 sequences of chest compressions were studied. Median chest compressions rate: 114 (104-130)/min. Median chest compressions depth: 4.5 (3.4-5.3) cm. Correlation between rate and depth: low (R2 = 0.12). Chest compressions in compliance with the recommended rate: 434 (46%). Rate >120/min in 285 (30%) cases and <100/min in 223 (23%) cases. Chest compressions in compliance with the recommended depth: 286 (30%). Depth >6 cm in 50 (5%) cases and <5 cm in 621 (65%) cases. Finally, chest compressions were in compliance with the guidelines for both rate and depth in 141 (15%) cases. The ratio of chest compressions in compliance with the recommended depth significantly decreased with the increase of the rate: 40% for a rate <100/min, 32% for a rate in the target (100-120/min) and 18% for a rate >100/min (P < 0.0001).

Discussion: The ratio of chest compressions in compliance with the recommended rate and depth was as low as 15%. The rate of chest compressions in compliance with the recommended depth significantly decreased when the chest compressions rate increased. To reach both recommended rate and depth seems illusive.