Is initial rhythm in OHCA a predictor of preceding no flow time? Implications for bystander response and ECPR candidacy evaluation

doi:10.1016/j.resuscitation.2018.05.002

Resuscitation

Volume 128, July 2018, Pages 88-92

https://doi.org/10.1016/j.resuscitation.2018.05.002 Get rights and content

Abstract

Objective

Shockable cardiac rhythms are associated with improved outcomes among out-of-hospital cardiac arrests (OHCA). Initial cardiac rhythm may also be predictive of a short preceding no-flow duration. We examined the relationship between no-flow duration and initial cardiac rhythm, which may demonstrate the urgency in rescuer response and assist with candidacy evaluation for extracorporeal-cardiopulmonary resuscitation (ECPR).

Methods

We examined consecutive adult OHCA’s identified by a prospective registry in British Columbia (2005–2016). We included those with witnessed OHCA but no bystander CPR. The variable of interest was no-flow duration, defined as time from 9-1-1 call to EMS arrival. We fit an adjusted logistic regression model to estimate the association of no-flow duration and initial cardiac rhythm. Among those with shockable initial rhythms, we calculated the cumulative proportion with no-flow durations under incremental time cut-offs.

Results

Of 26 621 EMS-treated OHCA’s, 2532 were included. Overall survival was 13.8%, and 34% had initial shockable rhythms. The probability of having an initial shockable rhythm decreased with increasing no-flow durations (adjusted OR 0.88 per minute, 95% CI 0.85–0.91). Among those found with initial shockable rhythms, 94% (95% CI 92–96%) had a no-flow time under 10 min.

Conclusion

The odds of a shockable initial rhythm declined with each additional minute of no-flow time, highlighting the importance of early access to defibrillation. Among those with initial shockable rhythms, the preceding no-flow duration was highly likely to be under 10 min, which may inform decisions about ECPR candidacy among select patients with unwitnessed arrests.

Introduction

Non-traumatic out-of-hospital cardiac arrest (OHCA) is a common health concern, affecting in approximately 325 000 and 40 000 people in the USA and Canada per year respectively [1,2]. Of EMS-treated OHCA, survival to hospital discharge range between 5–19% in North America [3]. Although historical details of events prior to cardiac arrests are often limited, several characteristics have been found to be independent predictors of good outcomes at hospital discharge, with the presence of ventricular fibrillation at initial rhythm evaluation typically demonstrating the strongest association [[1], [2], [3], [4], [5], [6]]. Ventricular fibrillation (VF), which is treatable with defibrillation, eventually degrades into non-shockable rhythms without intervention [7,8], and thus rescuer assessment and intervention prior to this rhythm change may be critical to patient outcomes.

Extracorporeal cardiopulmonary resuscitation (ECPR), can be used as a rescue therapy for OHCAs refractory to conventional management [9]. Due to its resource intensive nature, deployment is typically limited these to those deemed to have the best chances of successful outcomes [10]. Witnessed arrests are associated with improved outcomes in patients treated with conventional resuscitation [11], presumably due to shorter “no-flow” durations (the time with no organ perfusion, measured from the time of cardiac arrest to commencement of chest compressions) [12]. Unwitnessed arrests are often deemed ineligible for ECPR clinical protocols as the no-flow duration is unknown [[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21]]. However, the presence of an initial shockable rhythm may be an indicator of a short no-flow duration, regardless of whether the arrest was witnessed. If so, this may have implications for otherwise suitable ECPR candidates with initial shockable rhythms who are excluded based on the arrest being unwitnessed.

For these reasons, we sought to determine the relationship between no-flow duration and initial cardiac rhythm. We examined a cohort of patients with witnessed arrests and no bystander resuscitation, a population for which we could calculate the no-flow duration. These analyses may be helpful: (1) in demonstrating the urgency in rescuer response for OHCAs; and (2) in candidacy evaluation for ECPR among those with initial shockable rhythms but unknown no-flow durations (due to unwitnessed status).

Section snippets

Study setting

This study took place within the province of British Columbia (B.C.). The cardiac arrest registry in B.C., as part of the Resuscitation Outcomes Consortium [22], prospectively enrols consecutive EMS-assessed non-traumatic OHCAs within the four metropolitan regions in BC (Greater Victoria and Nanaimo, Greater Vancouver, the Fraser Valley, and Kelowna/Kamloops) collectively containing 3.3 million citizens (three quarters of the province’s population) [23]. The institutional ethics review boards

Characteristics of study subjects

Of 26 621 consecutive EMS-assessed cases of OHCA in the study period, we included 2 532 in this study (Fig. 1).

Main results

Patient characteristics are shown in Table 1. The median age was 72 (IQR 58–81), 69% were male, 19% occurred in a public place, and 837 (34%) had initial shockable rhythms. The median time no-flow duration was 6.5 min (IQR 5.1–8.2; 90%ile 10.4; Fig. 2). Survival was 27.9% and 6.9% among those with initial shockable rhythms and non-shockable rhythms, respectively.

Fig. 3 shows the

Discussion

We examined a cohort of patients with known no-flow durations (those with witnessed arrests and no bystander resuscitation) in order to investigate the association between no-flow duration and initial cardiac rhythm. Our data indicates that the odds of an initial shockable rhythm in an OHCA victim declines with increasing no-flow duration. Further, we found that in patients with initial shockable cardiac rhythms (whether or not ROSC is achieved), one can be very confident that the no-flow

Conclusion

The likelihood of an initial shockable cardiac rhythm declines with each additional minute of no-flow time, highlighting the importance of early access to defibrillation, which may be achieved though community Public Access Defibrillation programs with early bystander and EMS response. Among those found with initial shockable cardiac rhythms without preceding bystander resuscitation, it is highly likely that the no-flow time was less than 10 min, which may assist in ECPR candidacy evaluation

Funding

None.

Conflicts of interest

None.

Acknowledgements

None.

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LE arrival before EMS and ensuring both CPR and AED application is associated with significantly improved functional survival in OHCA patients not already receiving bystander CPR.
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Citation Excerpt :
As the response time and bystander CPR rate were unchanged in Western societies, the decreasing incidence of shockable rhythm could be attributed to improving coronary artery disease care and anti-arrhythmic management.24 However, certain studies have shown that bystander CPR can mitigate the rapid deterioration from a shockable rhythm to a non-shockable rhythm.13,14 Therefore, the increasing incidence of shockable rhythms over time in our study can be attributed to the increase in the bystander CPR rate, which could be attributed to the implementation of the DACPR bundle programs and improved public understanding of the advantages of early hands-only CPR.
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Clinical paperIs initial rhythm in OHCA a predictor of preceding no flow time? Implications for bystander response and ECPR candidacy evaluation

Abstract

Objective

Methods

Results

Conclusion

Introduction

Section snippets

Study setting

Characteristics of study subjects

Main results

Discussion

Conclusion

Funding

Conflicts of interest

Acknowledgements

Resuscitation

Resuscitation

Int J Cardiol

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Ann Emerg Med

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Clinical paper
Is initial rhythm in OHCA a predictor of preceding no flow time? Implications for bystander response and ECPR candidacy evaluation