Resuscitation Outcomes Consortium Sites Research Articles

Abstract 371: Using Defibrillator Bioimpedance Waveforms to Measure Ventilation During Continuous Chest Compression CPR

Introduction: For patients with out of hospital cardiac arrest, prompt return of circulation and ventilation is vitally important for survival. Techniques and devices have been developed to ensure emergency responders are providing high quality chest compression, but there has been little progress in the area of ventilation. Until an advanced airway is placed, there has been no practical way to measure ventilation. The aim of this study is to develop a method to measure ventilation during continuous chest compressions cardiopulmonary resuscitation (CPR) that can be used to monitor and improve quality of ventilation during out of hospital CPR. Hypothesis: Defibrillator transthoracic bioimpedance can be used to identify ventilation waveforms prior to placement of an advanced airway during continuous chest compressions CPR. Methods: We examined 391 patients’ defibrillator files from four Resuscitation Outcomes Consortium sites for the presence of waveforms that met previously developed criteria and were manually annotated. Criteria for an acceptable ventilation waveform were: waveform amplitude ≥0.5 Ohm and waveform duration ≥1 sec. We recorded the number of ventilations, return of spontaneous circulation, initial heart rhythm, and ventilation rates. Following annotation, 333 of the 391 patients’ files had the necessary intubation time recorded and an automated program precisely measured the amplitude and duration of each ventilation. We determined mean (±SD) waveform amplitude and duration of inflation and deflation pre and post airway placement. Significance was determined using Wilcoxon ranked sum test. Results: Comparing the pre and post airway measurements did not result in any significant differences, except in duration of inflation, which was 1.06 ± 0.41 sec and 1.11 ± 0.52 sec, respectively, (p <0.001). Ventilation waveforms had significantly lower amplitude and shorter duration during chest compressions than during pauses in compressions. Conclusion: Defibrillator transthoracic bioimpedance can be used to identify and monitor ventilations during continuous chest compressions CPR. Ventilation waveforms have lower amplitudes and shorter durations during chest compressions than during pauses in compressions.

Relationship Between Duration of Targeted Temperature Management, Ischemic Interval, and Good Functional Outcome From Out-of-Hospital Cardiac Arrest.

Tailoring hypothermia duration to ischemia duration may improve outcome from out-of-hospital cardiac arrest. We investigated the association between the hypothermia/ischemia ratio and functional outcome in a secondary analysis of data from the Resuscitation Outcomes Consortium Amiodarone, Lidocaine, or Placebo Study trial. Cohort study of out-of-hospital cardiac arrest patients screened for Resuscitation Outcomes Consortium-Amiodarone, Lidocaine, or Placebo Study. Multicenter study across North America. Adult, nontraumatic, out-of-hospital cardiac arrest patients screened for Resuscitation Outcomes Consortium-Amiodarone, Lidocaine, or Placebo Study who survived to hospital admission and received targeted temperature management between May 2012 and October 2015. Targeted temperature management in comatose survivors of out-of-hospital cardiac arrest. We defined hypothermia/ischemia ratio as total targeted temperature management time (initiation through rewarming) divided by calculated total ischemia time (approximate time of arrest [9-1-1 call or emergency medical services-witnessed] to return of spontaneous circulation). The primary outcome was hospital survival with good functional status (modified Rankin Score, 0-3) at hospital discharge. We fitted logistic regression models to estimate the association between hypothermia/ischemia ratio and the primary outcome, adjusting for demographics, arrest characteristics, and Resuscitation Outcomes Consortium enrolling site. A total of 3,429 patients were eligible for inclusion, of whom 36.2% were discharged with good functional outcome. Patients had a mean age of 62.0 years (SD, 15.8), with 69.7% male, and 58.0% receiving lay-rescuer cardiopulmonary resuscitation. Median time to return of spontaneous circulation was 21.1 minutes (interquartile range, 16.1-26.9), and median duration of targeted temperature management was 32.9 hours (interquartile range, 23.7-37.8). A total of 2,579 had complete data and were included in adjusted regression analyses. After adjustment for patient characteristics and Resuscitation Outcomes Consortium site, a greater hypothermia/ischemia ratio was associated with increased survival with good functional outcome (odds ratio, 2.01; 95% CI, 1.82-2.23). This relationship, however, appears to be primarily driven by time to return of spontaneous circulation in this patient cohort. Although a larger hypothermia/ischemia ratio was associated with good functional outcome after out-of-hospital cardiac arrest in this cohort, this association is primarily driven by duration of time to return of spontaneous circulation. Tailoring duration of targeted temperature management based on duration of time to return of spontaneous circulation or patient characteristics requires prospective study.

Hospital Variation in the Utilization and Implementation of Targeted Temperature Management in Out-of-Hospital Cardiac Arrest.

Background Targeted temperature management (TTM) for out-of-hospital cardiac arrest is associated with improved functional survival and is a class I recommendation in resuscitation guidelines. However, patterns of utilization of TTM and adherence to recommended TTM guidelines in contemporary practice are unknown. Methods and Results In a multicenter, prospective cohort of consecutive adults with non-traumatic out-of-hospital cardiac arrest in the Resuscitation Outcomes Consortium in 2012 to 2015, we identified all adults (≥18 years) who were potential candidates for TTM. Of 37 898 out-of-hospital cardiac arrest patients at 186 hospitals across 10 Resuscitation Outcomes Consortium sites, 8313 survived for ≥4 hours after hospital arrival, of which, 2878 (34.6%) received TTM. Mean age was 61.5 years and 36.3% were women. Median hospital rate of TTM use was 27% (interquartile range [IQR]: 14%, 45%), with an over 2-fold difference across sites after accounting for differences in presentation characteristics (median odds ratio, 2.10 [1.83-2.26]). Notably, TTM utilization decreased during the study period (57.5% [2012] to 26.5% [2015], P<0.001) including among shockable out-of-hospital cardiac arrest (73.4% to 46.3%, P<0.001). When administered, the median rate of deviation from one or more recommended practices was 60% (IQR: 40%, 78%). The median rate for delayed onset of TTM was 13% (IQR: 0%, 25%), varying by 70% for identical patients across 2 randomly chosen hospitals (median odds ratio 1.70 [1.39-1.97]). Similarly, the median rate for TTM <24 hours was 20% (IQR: 0%, 34%) and for achieved temperature <32°C was 18% (IQR: 0%, 39%), with marked variation across sites (median odds ratios of 1.44 [1.18-1.64] and 1.98 [1.62-2.31], respectively). Conclusions There has been a substantial decline in the utilization of TTM with significant variation in its real-world implementation. Further standardization of contemporary post-resuscitation practices, like TTM, is critical to ensure that their potential survival benefit is realized.

Association of Neighborhood Demographics With Out-of-Hospital Cardiac Arrest Treatment and Outcomes

We examined whether resuscitation care and outcomes vary by the racial composition of the neighborhood where out-of-hospital cardiac arrests (OHCAs) occur. To evaluate the association between bystander treatments (cardiopulmonary resuscitation and automatic external defibrillation) and timing of emergency medical services personnel on OHCA outcomes according to the racial composition of the neighborhood where the OHCA event occurred. This retrospective observational cohort study examined patients with OHCA from January 1, 2008, to December 31, 2011, using data from the Resuscitation Outcomes Consortium. Neighborhoods where OHCA occurred were classified by census tract, based on percentage of black residents: less than 25%, 25% to 50%, 51% to 75%, or more than 75%. Multilevel mixed-effects logistic regression modeling examined the association between racial composition of neighborhoods and OHCA survival, adjusting for patient, neighborhood, and treatment characteristics. Survival to discharge, return of spontaneous circulation on emergency department arrival, and favorable neurologic status at discharge. We examined 22 816 adult patients with nontraumatic OHCA at Resuscitation Outcomes Consortium sites in the United States. The median age of patients with OHCA was 64 years (interquartile range [IQR], 51-78). Compared with patients who experienced OHCA in neighborhoods with a lower proportion of black residents, those in neighborhoods with more than 75% black residents were slightly younger, were more frequently women, had lower rates of initial shockable rhythm, and less frequently experienced OHCA in a public location. The percentage of patients with OHCA receiving bystander cardiopulmonary resuscitation or a lay automatic external defibrillation was inversely associated with the percentage of black residents in neighborhoods. Compared with OHCA in predominantly white neighborhoods (<25% black), those with OHCA in mixed to majority black neighborhoods had lower adjusted survival rates to hospital discharge (25%-50% black: odds ratio, 0.76; 95% CI, 0.61-0.93; 51%-75% black: odds ratio, 0.67; 95% CI, 0.49-0.90; >75% black: odds ratio, 0.63; 95% CI, 0.50-0.79; P < .001). There was similar mortality risk for black and white patients with OHCA in each neighborhood racial quantile. When the primary model included geographic site, there was an attenuated nonsignificant association between racial composition in a neighborhood and survival. Those with OHCA in predominantly black neighborhoods had the lowest rates of bystander cardiopulmonary resuscitation and automatic external defibrillation use and significantly lower likelihood for survival compared with predominantly white neighborhoods. Improving bystander treatments in these neighborhoods may improve cardiac arrest survival.

Predicting Survival After Out-of-Hospital Cardiac Arrest: Role of the Utstein Data Elements

Survival after out-of-hospital cardiac arrest depends on the links in the chain of survival. The Utstein elements are designed to assess these links and provide the basis for comparing outcomes within and across communities. We assess whether these measures sufficiently predict survival and explain outcome differences. We used an observational, prospective data collection, case-series of adult persons with nontraumatic out-of-hospital cardiac arrest from December 1, 2005, through March 1, 2007, from the multisite, population-based Resuscitation Outcomes Consortium Epistry-Cardiac Arrest. We used logistic regression, receiver operating curves, and measures of variance to estimate the extent to which the Utstein elements predicted survival to hospital discharge and explained outcome variability overall and between 7 Resuscitation Outcomes Consortium sites. Analyses were conducted for all emergency medical services-treated cardiac arrests and for the subset of bystander-witnessed patient arrests because of presumed cardiac cause presenting with ventricular fibrillation or ventricular tachycardia. Survival was 7.8% overall (n=833/10,681) and varied from 4.6% to 14.7% across Resuscitation Outcomes Consortium sites. Among bystander-witnessed ventricular fibrillation or ventricular tachycardia, survival was 22.1% overall (n=323/1459) and varied from 12.5% to 41.0% across sites. The Utstein elements collectively predicted 72% of survival variability among all arrests and 40% of survival variability among bystander-witnessed ventricular fibrillation. The Utstein elements accounted for 43.6% of the between-site survival difference among all arrests and 22.3% of the between-site difference among the bystander-witnessed ventricular fibrillation subset. The Utstein elements predict survival but account for only a modest portion of outcome variability overall and between Resuscitation Outcomes Consortium sites. The results underscore the need for ongoing investigation to better understand characteristics that influence cardiac arrest survival.

The Random Dialing Survey as a Tool for Community Consultation for Research Involving the Emergency Medicine Exception From Informed Consent

In 1996, the Food and Drug Administration and the Department of Health and Human Services enacted rules allowing a narrow exception from informed consent for critically ill patients enrolled in emergency research. These include requirements for community consultation prior to trial implementation. Previous studies have noted difficulty in engaging the community. We seek to describe the experience with random dialing surveys as a tool for community consultation across 5 metropolitan regions in the United States. Random dialing surveys were used as part of the community consultation for an out-of-hospital clinical trial sponsored by the Resuscitation Outcomes Consortium. The survey method was designed to obtain a representative sample of the community according to population demographics and geography. Logistics of survey administration, role of the survey in community consultation, and survey results by population demographics are discussed. Random dialing surveys were conducted in 5 of 8 US Resuscitation Outcomes Consortium sites. Overall, 70% to 79% of respondents indicated they would be willing to be enrolled in this study. Support for the inclusion of children (aged 15 to 18 years) ranged from 52% to 71%. Respondents aged 18 to 34 years were more willing to participate in the trial than older age groups. Women and racial minorities were less likely to favor the inclusion of minors. Random dialing surveys provide an additional tool to engage the community and obtain a sample of the opinion of the population about research conducted under the emergency exception from informed consent regulations. Similar results were obtained across 5 diverse communities in the United States.