A randomized trial of continuous versus interrupted chest compressions in out-of-hospital cardiac arrest: rationale for and design of the Resuscitation Outcomes Consortium Continuous Chest Compressions Trial

Time in therapeutic range for targeted temperature management and outcomes following out-of-hospital cardiac arrest

OBJECTIVE

For comatose survivors of out-of-hospital cardiac arrest (OHCA), current guidelines recommend targeted temperature management (TTM) with a goal temperature of 32 °C-36 °C for at least 24 h. We examined adherence to temperature targets, quantified as time-in-therapeutic range (TTR), and association of TTR with survival and neurologic outcomes.

METHODS

We conducted a retrospective cohort study of the Resuscitation Outcomes Consortium-Continuous Chest Compressions trial, including adults with OHCA who underwent TTM for >12 h. We imputed continuous temperatures between consecutive temperature measurements using the linear interpolation method and calculated TTR for multiple target temperatures. The association of TTR with survival to hospital discharge and favorable neurological outcome was evaluated using hierarchical regression models.

MAIN RESULTS

Among 2,637 patients (mean age 62.3 years, 29.9 % female), the median duration of TTR for TTM between 32 °C-36 °C was 23 (IQR: 21-24) hours with a median time outside therapeutic range of 0.9 (IQR: 0.0-4.2) hours. In risk-adjusted analyses, there was no association of TTR of 32 °C-36 °C with overall survival (OR 1.00 [95 % CI, 0.90-1.10]) or favorable neurologic outcome (1.02 [95 % CI, 0.90-1.14]). However, in assessments of TTR 33 °C-36 °C, there was a significant association with favorable neurologic survival (OR 1.12 [1.01-1.25]) but not overall survival (OR 1.04 [0.94-1.15]).

CONCLUSIONS

Among patients with OHCA who underwent TTM, we found variability in adherence to guideline-recommended treatment targets. Higher TTR was not associated with overall survival, but for certain temperature thresholds, TTR was associated with favorable neurologic outcome.

Emergency medical services employing intra-arrest transport less frequently for out-of-hospital cardiac arrest have higher survival and favorable neurological outcomes

BACKGROUND

There is substantial regional variation in out-of-hospital cardiac arrest (OHCA) survival. We investigated whether regional emergency medical services (EMS) intra-arrest transport (IAT) practices are associated with patient outcomes.

METHODS

We performed a secondary analysis of a multi-center North American clinical trial dataset, which enrolled EMS-treated adult OHCA cases from 49 regional population-based clusters. The exposure of interest was regional-level intra-arrest transport (IAT), calculated as the proportion of cases in each cluster transported to hospital prior to return of spontaneous circulation, examined as quartiles and as a continuous variable. Multilevel mixed-effects logistic regression modeling estimated the association between regional IAT with survival to hospital discharge and favorable neurologic status (modified Rankin Scale ≤ 3) at hospital discharge.

RESULTS

Of 26,148 subjects (median age 68 years; 36% female; 23% shockable initial rhythm) 2424 (9.3%), survived to hospital discharge and 1993 (7.6%) had favourable neurological outcomes. Across regional clusters, IAT ranged from 0.84% to 75% (quartiles <6.2%, 6.2-19.6%, 19.6-30.4%, and ≥30.4%). For each quartile, 13.3%, 7.9%, 7.4%, and 4.8% survived, and 10.4%, 7.8%, 7.4%, and 4.8% had favourable neurological status. Regional IAT (per 10% change) was associated with decreased probability of survival (AOR 0.86, 95% CI 0.82-0.91) and favorable neurological outcome (AOR 0.80, 95% CI 0.76-0.85).

CONCLUSION

Treatment within a region that utilizes IAT less frequently was associated with improved clinical outcomes at hospital discharge. These findings may account for some of the known regional variation in OHCA outcomes.

CPR compression strategy 30:2 is difficult to adhere to, but has better survival than continuous chest compressions when done correctly

BACKGROUND

A large, randomized trial showed no significant difference in survival to discharge between cardiopulmonary resuscitation (CPR) strategies of 30 compressions with pause for 2 ventilations per cycle (30:2) and continuous chest compression with asynchronous ventilations (CCC). Data from the same trial suggested that adherence to the intended CPR strategy was associated with significantly greater survival. We sought to determine the adherence rate with intended strategy and then explore the association of adherence with survival to discharge in the Resuscitation Outcomes Consortium (ROC).

METHODS

This secondary analysis of data from the ROC included three interventional trials and a prospective registry. We modified an automated software algorithm that classified care as 30:2 or CCC before intubation based on compression segment length (defined as the elapsed time from start of compressions to subsequent pause of ≥2 s), number of pauses per minute ≥2 s in length and chest compression fraction. Intended CPR strategy for individual agencies was based on study randomization (during trial phase) or local standard of care (during registry phase). We defined CPR delivered as adherent when its classification matched the intended strategy. We characterized adherence with intended strategy across trial and registry periods. We examined its association with survival to hospital discharge using multivariate logistic regression after adjustment for Utstein and other potential confounders. Effect modification with intended strategy was assessed through a multiplicative interaction term.

RESULTS

Included were 26,810 adults with out of hospital cardiac arrest, of which 10,942 had an intended strategy of 30:2 and 15,868 an intended strategy of CCC. The automated algorithm classified 12,276 cases as CCC, 7037 as 30:2 and left 7497 as unclassified. Adherence to intended strategy was 54.4%; this differed by intended strategy (58.6% for CCC vs 48.3% for 30:2). Overall adherence was less during the registry phase as compared to during the trial phase(s). The association between adherence and survival was modified by treatment arm (CCC OR: 0.72, 95% CI: 0.64-0.81 vs 30:2 OR: 1.05, 95% CI: 0.90-1.22; interaction p-value<0.01) after adjustment for known confounders.

CONCLUSION

For intended strategy CCC, survival was significantly lower, OR (95%CI) = 0.72 (0.64, 0.81), when adhered to while for intended strategy 30:2, survival was higher, OR (95%CI) = 1.05 (0.90, 1.22), when adhered to. Intended strategy of 30:2 had lower adherence rates than CCC possibly a result of being a more difficult strategy to administer.

Current evidence of survival benefit between chest-compression only versus standard cardiopulmonary resuscitation in out-of-hospital cardiac arrest : Updated systematic review and meta-analysis of randomized controlled trials with trial sequential analysis

BACKGROUND

Evidence to support a better cardiopulmonary resuscitation method between standard vs. continuous chest compression (STD-CPR vs. CCC-CPR) is lacking.

MATERIALS AND METHODS

Our systematic review followed PRISMA guidelines. We searched PubMed, ScienceDirect, EBSCOhost, and ProQuest database from 1985 to 26 September 2019 restricted to randomized controlled trial, human study, and English articles. Quality assessment of between-study heterogeneity and a trial sequential analysis (TSA) were conducted. We estimated overall significance with 80% power and adjusted Z values thresholds using O'Brien-Fleming α‑spending function. Required information size with 21% relative risk using the estimation between-group incidences provided from the median rate across trials was determined. Inconclusive TSA result will lead to size estimation of future RCT. Quality of evidence was analyzed using Grading of Recommendations Assessment, Development and Evaluation (GRADE) Handbook and TSA.

RESULTS

Based on three trials in OHCA with dispatcher-guided and bystander-initiated CPR, our meta-analysis favors CCC-CPR for survival to hospital discharge, compared to STD-CPR (RR [Risk Ratio] = 1.21[1.01-1.46], 95% CI, p = 0.68, I² = 0). However, current meta-analyses with 3031 patients appeared to be inconclusive. There is a significant risk of type 1 error and therefore, results are potentially false positive. It is estimated that a minimal of 4331 patients needed to deem a conclusive result and a total of 5894 patients with similar risk profile required to stabilize statistic results in future trials. Quality of evidence is downgraded to moderate due to serious imprecision based on TSA.

CONCLUSION

Based on these analyses, evidence is inadequate to conclude the superiority of one CPR method over the other. Further trials with larger numbers of patients are needed to deem a conclusive and stable meta-analysis.

Door-to-Targeted Temperature Management Initiation Time and Outcomes in Out-of-Hospital Cardiac Arrest: Insights From the Continuous Chest Compressions Trial

Background

Targeted temperature management (TTM) is a recommended treatment modality to improve neurological outcomes in patients with out‐of‐hospital cardiac arrest. The impact of the duration from hospital admission to TTM initiation (door‐to‐TTM; DTT) on clinical outcomes has not been well elucidated. We hypothesized that shorter DTT initiation intervals would be associated with improved survival with favorable neurological outcome.

Methods and Results

We performed a post hoc analysis of nontraumatic paramedic‐treated out‐of‐hospital cardiac arrests. The primary outcome was favorable neurological status at hospital discharge, with a secondary outcome of survival to discharge. We fit a logistic regression analysis to determine the association of early compared with delayed DTT, dichotomized by the median DTT duration, and outcomes. Of 3805 patients enrolled in the CCC (Continuous Chest Compressions) Trial in British Columbia, 570 were included in this analysis. There was substantial variation in DTT among patients receiving TTM. The median DTT duration was 122 minutes (interquartile range 35‐218). Favorable neurological outcomes in the early and delayed DTT groups were 48% and 38%, respectively. Compared with delayed DTT (interquartile range 167‐319 minutes), early DTT (interquartile range 20‐81 minutes) was associated with survival (adjusted odds ratio 1.56, 95% CI 1.02‐2.38) but not with favorable neurological outcomes (adjusted odds ratio 1.45, 95% CI, 0.94‐2.22) at hospital discharge.

Conclusions

There was wide variability in the initiation of TTM among comatose out‐of‐hospital cardiac arrest survivors. Initiation of TTM within 122 minutes of hospital admission was associated with improved survival. These results support in‐hospital efforts to achieve early DTT among out‐of‐hospital cardiac arrest patients admitted to the hospital.

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The association of scene-access delay and survival with favourable neurological status in patients with out-of-hospital cardiac arrest

BACKGROUND

Rapid emergency medical service (EMS) response after out-of-hospital cardiac arrest (OHCA) is a major determinant of survival, however this is typically measured until EMS vehicle arrival. We sought to investigate whether the interval from EMS vehicle arrival to patient attendance (curb-to-care interval [CTC]) was associated with patient outcomes.

METHODS

We performed a secondary analysis of the "CCC Trial" dataset, which includes EMS-treated adult non-traumatic OHCA. We fit an adjusted logistic regression model to estimate the association between CTC interval (divided into quartiles) and the primary outcome (survival with favourable neurologic status at hospital discharge; mRS ≤ 3). We described the CTC interval distribution among enrolling clusters.

RESULTS

We included 24,685 patients: median age was 68 (IQR 56-81), 23% had initial shockable rhythms, and 7.6% survived with favourable neurological status. Compared to the first quartile (≤62 s), longer CTC quartiles (63-115, 116-180, and ≥181 s) demonstrated the following associations with survival with favourable neurological status: adjusted odds ratios 0.95, 95% CI 0.83-1.09; 0.77, 95% CI 0.66-0.89; 0.66, 95% CI 0.56-0.77, respectively. Of the 49 study clusters, median CTC intervals ranged from 86 (IQR 58-130) to 179 s (IQR 112-256).

CONCLUSION

A lower CTC interval was associated with improved patient outcomes. These results demonstrate a wide range of access metrics within North America, and provide a rationale to create protocols to mitigate access obstacles. A 2-min CTC threshold may represent an appropriate target for quality improvement.

Gastric insufflation during cardiopulmonary resuscitation: A study in human cadavers

INTRODUCTION

Bag-valve-mask ventilation is the first-line ventilation method during cardiopulmonary resuscitation (CPR). Risks include excessive volume delivery and gastric insufflation, the latter increasing the risk of pneumonia. The efficacy of ventilation can also be reduced by airway closure. We hypothesized that continuous chest compression (CC) could limit the risk of gastric insufflation compared to the recommended 30:2 interrupted CC strategy. This experimental study was performed in human "Thiel" cadavers to assess the respective impact of discontinuous vs. continuous chest compressions on gastric insufflation and ventilation during CPR.

METHODS

The 30:2 interrupted CC technique was compared to continuous CC in 5 non-intubated cadavers over a 6 min-period. Flow and Airway Pressure were measured at the mask. A percutaneous gastrostomy allowed measuring the cumulative gastric insufflated volume. Two additional cadavers were equipped with esophageal and gastric catheters instead of the gastrostomy.

RESULTS

For the 7 cadavers studied (4 women) median age of death was 79 [74-84] years. After 6 min of CPR, the cumulative gastric insufflation measured in 5 cadavers was markedly reduced during continuous CC compared to the interrupted CC strategy: (1.0 [0.8-4.1] vs. 5.9 [4.0-5.6] L; p < 0.05) while expired minute ventilation was slightly higher during continuous than interrupted CC (1.9 [1.4-2.8] vs. 1.6 [1.1-2.7] L/min; P < 0.05). In 2 additional cadavers, the progressive rise in baseline gastric pressure was lower during continuous CC than interrupted CC (1 and 2 cmH₂O vs. 12 and 5.8 cmH₂O).

CONCLUSION

Continuous CC significantly reduces the volume of gas insufflated in the stomach compared to the recommended 30:2 interrupted CC strategy. Ventilation actually delivered to the lung is also slightly increased by the strategy.

Study Monitoring in Emergency Care Trials: Lessons from the Resuscitation Outcomes Consortium Continuous Chest Compressions Trial

OBJECTIVE

Clinical trial investigators often assemble internal study monitoring committees (SMCs) to measure individual or group adherence with trial performance benchmarks. We examined the processes and results of study monitoring in an international trial of out-of-hospital cardiac arrest.

METHODS

We studied SMC operations for the Resuscitation Outcomes Consortium (ROC) Continuous Chest Compressions (CCC) trial, which compared continuous with interrupted chest compressions upon survival after out-of-hospital cardiac arrest. The SMC defined trial performance benchmarks, which included compliance with the intervention, cardiopulmonary resuscitation (CPR) process data availability and timely data completion. Trial investigators received monthly performance reports. We determined rates of trial noncompliance and suspension from the trial.

RESULTS

ROC-CCC enrolled a total of 23,711 subjects in the primary analysis population. Across 113 enrolling agencies, the SMC monitored performance for a total 2,367 agency-months. Emergency medical services agencies were on probation for a total of 178 (7.5%) agency-months. Fifty-five agencies were placed on probation at least once, of which 78% improved their performance and were approved for continued participation in the trial. A total of 12 agencies were suspended from trial participation. Data monitoring resulted in high-quality CPR (mean chest compression fraction = 0.80), 87% CPR process availability and timely data completion (75th and 95th percentiles prehospital data = 22 and 57 days; hospital data = 58 and 118 days).

CONCLUSIONS

Study monitoring procedures may play an important role in ensuring the performance quality in acute care clinical trials.

A Local Sensitivity Analysis of the Trial of Continuous or Interrupted Chest Compressions during Cardiopulmonary Resuscitation: Is a Local Protocol Change Required?

Objective

The “Trial of Continuous (CCC) or Interrupted Chest Compressions (ICC) during Cardiopulmonary Resuscitation (CPR)” compared two CPR strategies for out-of-hospital cardiac arrest (OHCA). Although results were neutral, there was suggestion of benefit for ICC. However, nearly 50% of study patients had a protocol violation; regional variations may have played a role in protocol adherence and outcomes. We analyzed our British Colombia (BC) cohort to decide whether a protocol change from CCC to ICC was justified.

Methods

This was a post-hoc analysis of BC-enrolled study patients. The primary between-group comparison was favorable neurological outcome (modified Rankin scale ≤ 3) using intention-to-treat. Secondary analyses compared those treated per-protocol (adjusted) and the top compliant clusters (unadjusted). We classified protocol violations using a structured algorithm. We used logistic regression and computed the difference in probabilities using the marginal standardization method with bootstrapping to calculate confidence intervals.

Results

There were 3769 patients included, with a median age of 69 years (IQR: 56–80). There were protocol violations in 3.2% of those in the CCC group and 27% of those in the ICC group. In patients randomized to CCC or ICC, 11.2% and 10.8% (risk difference 0.42%; 95% CI -1.58, 2.41) had favorable neurological outcomes, respectively. In the per-protocol and top compliant clusters comparisons, risk differences were 0.25% (95% CI -1.70, 2.25) and 2.95% (95% CI -0.68, 6.58).

Conclusion

Our comparisons suggest that CCC may be the preferred strategy in our region and is likely not resulting in worse outcomes. Based on the original study and our local analysis, we found no compelling reasons to change our local strategy from CCC to ICC.

Prehospital sodium bicarbonate use could worsen long term survival with favorable neurological recovery among patients with out-of-hospital cardiac arrest

BACKGROUND

Sodium bicarbonate (SB) is widely used for resuscitation in out-of- hospital cardiac arrest (OHCA); however, its effect on long term outcomes is unclear.

METHODS

From 2005-2016, we prospectively conducted a province-wide population-based observational study including adult non-traumatic OHCA patients managed by paramedics. SB was administered by paramedics based on their clinical assessments. To examine the association of SB administration and survival and favorable neurological outcome to hospital discharge, defined as modified Rankin scale of 3 or less, we performed a multivariable logistic regression analysis: (1) within propensity score matched comparison groups, and; (2) within the full cohort with missing variables addressed by multiple imputation techniques.

RESULTS

Of 15 601 OHCA patients, 13,865 were included in this study with 5165 (37.3%) managed with SB. In the SB treated group, 118 (2.3%) patients survived and 62 (1.2%) had favorable neurological outcomes to hospital discharge, compared to 1699 (19.8%) and 831 (10.6%) in the non-SB treated group, respectively. In the 1:1 propensity matched cohort including 5638 OHCA patients, SB was associated with decreased probability of outcomes (adjusted OR for survival: 0.64, 95% CI 0.45-0.91, and adjusted OR for favorable neurological outcome: 0.59, 95% CI 0.39-0.88, respectively). The association remained consistent in the multiply imputed cohort (adjusted OR 0.48, 95 CI 0.36-0.64, and adjusted OR 0.54, 95% CI 0.38-0.76, respectively).

CONCLUSIONS

In OHCA patients, prehospital SB administration was associated with worse survival rate and neurological outcomes to hospital discharge.

Compression-to-ventilation ratio and incidence of rearrest-A secondary analysis of the ROC CCC trial

BACKGROUND

Previous work has demonstrated that when out-of-hospital cardiac arrest (OHCA) patients achieve return of spontaneous circulation (ROSC), but subsequently have another cardiac arrest prior to hospital arrival (rearrest), the probability of survival to hospital discharge is significantly decreased. Additionally, few modifiable factors for rearrest are known. We sought to examine the association between rearrest and compression-to-ventilation ratio during cardiopulmonary resuscitation (CPR) and to confirm the association between rearrest and outcomes.

HYPOTHESIS

Rearrest incidence would be similar between cases treated with 30:2 or continuous chest compression (CCC) CPR, but inversely related to survival and good neurological outcome.

METHODS

We conducted a secondary analysis of a large randomized-controlled trial of CCC versus 30:2 CPR for the treatment of OHCA between 2011 and 2015 among 8 sites of the Resuscitation OUTCOMES: Consortium (ROC). Patients were randomized through an emergency medical services (EMS) agency-level cluster randomization design to receive either 30:2 or CCC CPR. Case data were derived from prehospital patient care reports, digital defibrillator files, and hospital records. The primary analysis was an as-treated comparison of the proportion of patients with a rearrest for patients who received 30:2 versus those who received CCC. In addition, we assessed the association between rearrest and both survival to hospital discharge and favorable neurological outcome (Modified Rankin Score≤3) in patients with and without ROSC upon ED arrival using multivariable logistic regression adjusting for age, sex, initial rhythm and measures of CPR quality.

RESULTS

There were 14,109 analyzable cases that were determined to have definitively received either CCC or 30:2 CPR. Of these, 4713 had prehospital ROSC and 2040 (43.2%) had at least one rearrest. Incidence of rearrest was not significantly different between patients receiving CCC and 30:2 (44.1% vs 41.8%; adjusted OR: 1.01; 95% CI: 0.88, 1.16). Rearrest was significantly associated with lower survival (23.3% vs 36.9%; adjusted OR: 0.46; 95%CI: 0.36-0.51) and worse neurological outcome (19.4% vs 30.2%; adjusted OR: 0.46; 95%CI: 0.38, 0.55).

CONCLUSION

Rearrest occurrence was not significantly different between patients receiving CCC and 30:2, and was inversely associated with survival to hospital discharge and MRS.

Design and implementation of the Resuscitation Outcomes Consortium Pragmatic Airway Resuscitation Trial (PART)

Airway management is an important component of resuscitation from out-of-hospital cardiac arrest (OHCA). The optimal approach to advanced airway management is unknown. The Pragmatic Airway Resuscitation Trial (PART) will compare the effectiveness of endotracheal intubation (ETI) and Laryngeal Tube (LT) insertion upon 72-h survival in adult OHCA. Encompassing United States Emergency Medical Services agencies affiliated with the Resuscitation Outcomes Consortium (ROC), PART will use a cluster-crossover randomized design. Participating subjects will include adult, non-traumatic OHCA requiring bag-valve-mask ventilation. Trial interventions will include (1) initial airway management with ETI and (2) initial airway management with LT. The primary and secondary trial outcomes are 72-h survival and return of spontaneous circulation. Additional clinical outcomes will include airway management process and adverse events. The trial will enroll a total of 3000 subjects. Results of PART may guide the selection of advanced airway management strategies in OHCA.

EuReCa and international resuscitation registries

PURPOSE OF REVIEW

This review outlines knowledge on the epidemiology of out-of-hospital cardiac arrest (OHCA) internationally and the contribution that resuscitation registries make to OHCA research. The review focuses on recent advances in the European Cardiac Arrest Registry project, EuReCa.

RECENT FINDINGS

Although literature describing the epidemiology of OHCA has proliferated in recent years, a 2010 systematic review by Berdowski et al. remains a most important publication, allowing international comparison of OHCA incidence and outcome. Recent literature supports the view that resuscitation registers are excellent sources of data on OHCA. Notable publications describe geographic variation in incidence, improvements in survival and the utility of registers in the development of survival prediction models.

SUMMARY

Data from resuscitation registries are an invaluable source of information on the incidence, management and outcome of OHCA. Registries can be used to generate hypotheses for clinical research and registry data may even be used to facilitate clinical trials. To develop international research collaboration, registries must be based on the same dataset and definitions, and include descriptions of data collection methodologies and emergency medical service (EMS) configurations. If such standardization can be achieved, the possibility of an international resuscitation registry might be realized, leading to important OHCA research opportunities worldwide.

Trial of Continuous or Interrupted Chest Compressions during CPR

BACKGROUND

During cardiopulmonary resuscitation (CPR) in patients with out-of-hospital cardiac arrest, the interruption of manual chest compressions for rescue breathing reduces blood flow and possibly survival. We assessed whether outcomes after continuous compressions with positive-pressure ventilation differed from those after compressions that were interrupted for ventilations at a ratio of 30 compressions to two ventilations.

METHODS

This cluster-randomized trial with crossover included 114 emergency medical service (EMS) agencies. Adults with non-trauma-related cardiac arrest who were treated by EMS providers received continuous chest compressions (intervention group) or interrupted chest compressions (control group). The primary outcome was the rate of survival to hospital discharge. Secondary outcomes included the modified Rankin scale score (on a scale from 0 to 6, with a score of ≤3 indicating favorable neurologic function). CPR process was measured to assess compliance.

RESULTS

Of 23,711 patients included in the primary analysis, 12,653 were assigned to the intervention group and 11,058 to the control group. A total of 1129 of 12,613 patients with available data (9.0%) in the intervention group and 1072 of 11,035 with available data (9.7%) in the control group survived until discharge (difference, -0.7 percentage points; 95% confidence interval [CI], -1.5 to 0.1; P=0.07); 7.0% of the patients in the intervention group and 7.7% of those in the control group survived with favorable neurologic function at discharge (difference, -0.6 percentage points; 95% CI, -1.4 to 0.1, P=0.09). Hospital-free survival was significantly shorter in the intervention group than in the control group (mean difference, -0.2 days; 95% CI, -0.3 to -0.1; P=0.004).

CONCLUSIONS

In patients with out-of-hospital cardiac arrest, continuous chest compressions during CPR performed by EMS providers did not result in significantly higher rates of survival or favorable neurologic function than did interrupted chest compressions. (Funded by the National Heart, Lung, and Blood Institute and others; ROC CCC ClinicalTrials.gov number, NCT01372748.).