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

Abstract

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 12 min (95% confidence interval: 11–13 min) and LF greater than 33 min (95% confidence interval: 29–45 min), 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 40 min) in the setting of initial shockable cardiac rhythm is associated with greater than 1% survival with NF less than 18 min. 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.

Introduction

Sudden cardiac arrest accounts annually for 600,000 deaths in industrialized countries. Time to treatment is recognized as a main predictor of survival.¹ Duration of resuscitation efforts is widely recognized as a major determinant of survival after out-of-hospital cardiac arrest (OHCA). Duration of resuscitation may be defined as the sum of two distinct intervals: (1) no-flow ([NF]; interval from collapse to initiation of CPR) and (2) low-flow ([LF]; interval from start of cardiopulmonary resuscitation (CPR) to return of spontaneous circulation (ROSC) or termination of resuscitation).² Relatively few published studies have examined the impact of low-flow and no-flow intervals on clinical outcomes.1, 3, 4 However these two factors are widely recognized as the most important variables associated with long-term survival without sequelae.⁵ Two recent studies pointed out this correlation, based on nationwide registries.1, 3 The first study demonstrated a very robust correlation between the no-flow (NF) interval and survival status, with a rate of survival less than one percent when duration of no-flow exceeded 14 min.¹ In the second study, the authors suggested a strong association between duration of CPR (low-flow) and rate of ROSC with significant increase in survival when institutionally-imposed duration of CPR (low-flow) exceeded 30 min.³ The results were similar in the setting of in-hospital cardiac arrest.⁵ No systematic studies, however, have evaluated the impact of both NF and LF intervals in terms of survival without sequelae and the interaction of these two time parameters. In fact, one might anticipate that prognosis should be inversely proportional to LF and NF. Clinicians often feel helpless in assessing the appropriate length of resuscitation attempts when considering termination of efforts. Unfortunately, national and international guidelines have not adequately addressed this issue. European Resuscitation Council Guidelines for Resuscitation 2015 state that asystole for more than 20 min in the absence of a reversible cause and with ongoing advanced resuscitation constitutes a reasonable ground for stopping further resuscitation attempts.⁶ Other authors have opined that it is reasonable to stop resuscitation after a patient has been in asystole for more than 10 min, if there is no readily identified and reversible cause.⁷ A quantitative understanding of the relation between LF, NF and survival may help emergency response teams to evaluate the chance of survival knowing two values (NF, LF), aiding in the decision to terminate cardio-pulmonary resuscitation (CPR) or to implement other strategies, such as extracorporeal resuscitation (ECPR) and/or non-heart beating donor orientation (NHBD).8, 9

In the current study, our primary aim was to determine the association between survival without neurologic sequelae and values of NF and LF in the setting of witnessed OHCA of medical (non-traumatic) origin. A secondary aim was to determine the set of values of NF and LF in which CPR may be considered as futile.