Relation between chest compression rate and depth: the ENFONCE Study.

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.

Cardiopulmonary resuscitation duration and survival in out-of-hospital cardiac arrest patients.

AIM: Relationship between cardiopulmonary arrest and resuscitation (CPR) durations and survival after out-of-hospital cardiac arrest (OHCA) remain unclear. Our primary aim was to determine the association between survival without neurologic sequelae and cardiac arrest intervals in the setting of witnessed OHCA. METHODS: We analyzed 27,301 non-traumatic, witnessed OHCA patients in France included in the national registry from June 1, 2011 through December 1, 2015. We analyzed cardiac arrest intervals, designated as no-flow (NF; from collapse to start of CPR) and low-flow (LF; from start of CPR to cessation of resuscitation) in relation to 30-day survival without sequelae. We determined the influence of recognized prognostic factors (age, gender, initial rhythm, location of cardiac arrest) on this relation. RESULTS: For the entire cohort, the area delimited by a value of NF greater than 12min (95% confidence interval: 11-13min) and LF greater than 33min (95% confidence interval: 29-45min), yielded a probability of 30-day survival of less than 1%. These sets of values were greatly influenced by initial cardiac arrest rhythm, age, sex and location of cardiac arrest. Extended CPR duration (greater than 40min) in the setting of initial shockable cardiac rhythm is associated with greater than 1% survival with NF less than 18min. The NF interval was highly influential on the LF interval regardless of outcome, whether return of spontaneous circulation (p<0.001) or death (p<0.001). CONCLUSION: NF duration must be considered in determining CPR duration in OHCA patients. The knowledge of (NF, LF) curves as function of age, initial rhythm, location of cardiac arrest or gender may aid in decision-making vis-à-vis the termination of CPR or employment of advanced techniques.