David T. Travis

Manual vs. integrated automatic load-distributing band CPR with equal survival after out of hospital cardiac arrest. The randomized CIRC trial

OBJECTIVE To compare integrated automated load distributing band CPR (iA-CPR) with high-quality manual CPR (M-CPR) to determine equivalence, superiority, or inferiority in survival to hospital discharge. METHODS Between March 5, 2009 and January 11, 2011 a randomized, unblinded, controlled group sequential trial of adult out-of-hospital cardiac arrests of presumed cardiac origin was conducted at three US and two European sites. After EMS providers initiated manual compressions patients were randomized to receive either iA-CPR or M-CPR. Patient follow-up was until all patients were discharged alive or died. The primary outcome, survival to hospital discharge, was analyzed adjusting for covariates, (age, witnessed arrest, initial cardiac rhythm, enrollment site) and interim analyses. CPR quality and protocol adherence were monitored (CPR fraction) electronically throughout the trial. RESULTS Of 4753 randomized patients, 522 (11.0%) met post enrollment exclusion criteria. Therefore, 2099 (49.6%) received iA-CPR and 2132 (50.4%) M-CPR. Sustained ROSC (emergency department admittance), 24h survival and hospital discharge (unknown for 12 cases) for iA-CPR compared to M-CPR were 600 (28.6%) vs. 689 (32.3%), 456 (21.8%) vs. 532 (25.0%), 196 (9.4%) vs. 233 (11.0%) patients, respectively. The adjusted odds ratio of survival to hospital discharge for iA-CPR compared to M-CPR, was 1.06 (95% CI 0.83-1.37), meeting the criteria for equivalence. The 20 min CPR fraction was 80.4% for iA-CPR and 80.2% for M-CPR. CONCLUSION Compared to high-quality M-CPR, iA-CPR resulted in statistically equivalent survival to hospital discharge.

Pre-shock chest compression pause effects on termination of ventricular fibrillation/tachycardia and return of organized rhythm within mechanical and manual cardiopulmonary resuscitation☆

BACKGROUND Shorter manual chest compression pauses prior to defibrillation attempts is reported to improve the defibrillation success rate. Mechanical load-distributing band (LDB-) CPR enables shocks without compression pause. We studied pre-shock pause and termination of ventricular fibrillation/pulseless ventricular tachycardia 5s post-shock (TOF) and return of organized rhythm (ROOR) with LDB and manual (M-) CPR. METHODS In a secondary analysis from the Circulation Improving Resuscitation Care trial, patients with initial shockable rhythm and interpretable post-shock rhythms were included. Pre-shock rhythm, pause duration (if any), and post-shock rhythm were obtained for each shock. Associations between TOF/ROOR and pre-shock pause duration, including no pause shocks with LDB-CPR, were analyzed with Chi-square test. A p-value <0.05 was considered statistically significant. RESULTS For TOF and ROOR analyses we included 417 LDB-CPR patients with 1476 and 1438 shocks, and 495 M-CPR patients with 1839 and 1796 shocks, respectively. For first shocks with LDB-CPR, pre-shock pause was associated with TOF (p=0.049) with lowest TOF (77%) for shocks given without pre-shock compression pause. This association was not significant when all shocks were included (p=0.07) and not for ROOR. With M-CPR there were no significant associations between shock-related chest compression pause duration and TOF or ROOR. CONCLUSION For first shocks with LDB-CPR, termination of fibrillation was associated with pre-shock pause duration. There was no association for the rate of return of organized rhythm. For M-CPR, where no shocks were given during continuous chest compressions, there were no associations between pre-shock pause duration and TOF or ROOR.

Why do some studies find that CPR fraction is not a predictor of survival

INTRODUCTION An 80% chest compression fraction (CCF) during resuscitation is recommended. However, heterogeneous results in CCF studies were found during the 2015 Consensus on Science (CoS), which may be because chest compressions are stopped for a wide variety of reasons including providing lifesaving care, provider distraction, fatigue, confusion, and inability to perform lifesaving skills efficiently. OBJECTIVE The effect of confounding variables on CCF to predict cardiac arrest survival. METHODS A secondary analysis of emergency medical services (EMS) treated out-of-hospital cardiac arrest (OHCA) patients who received manual compressions. CCF (percent of time patients received compressions) was determined from electronic defibrillator files. Two Sample Wilcoxon Rank Sum or regression determined a statistical association between CCF and age, gender, bystander CPR, public location, witnessed arrest, shockable rhythm, resuscitation duration, study site, and number of shocks. Univariate and multivariate logistic regressions were used to determine CCF effect on survival. RESULTS Of 2132 patients with manual compressions 1997 had complete data. Shockable rhythm (p<0.001), public location (p<0.004), treatment duration (p<0.001), and number of shocks (p<0.001) were associated with lower CCF. Univariate logistic regression found that CCF was inversely associated with survival (OR 0.07; 95% CI 0.01-0.36). Multivariate regression controlling for factors associated with survival and/or CCF found that increasing CCF was associated with survival (OR 6.34; 95% CI 1.02-39.5). CONCLUSION CCF cannot be looked at in isolation as a predictor of survival, but in the context of other resuscitation activities. When controlling for the effects of other resuscitation activities, a higher CCF is predictive of survival. This may explain the heterogeneity of findings during the CoS review.

Minimizing pre-shock chest compression pauses in a cardiopulmonary resuscitation cycle by performing an earlier rhythm analysis☆

BACKGROUND Guidelines recommend 2min of CPR after defibrillation attempts followed by ECG analysis during chest compression pause. This pause may reduce the likelihood of return of spontaneous circulation (ROSC) and survival. We have evaluated the possibility of analysing the rhythm earlier in the CPR cycle in an attempt to replace immediate pre-shock rhythm analysis. METHODS AND RESULTS The randomized Circulation Improving Resuscitation Care (CIRC) trial included patients with out of hospital cardiac arrest of presumed cardiac aetiology. Defibrillator data were used to categorize ECG rhythms as shockable or non-shockable 1min post-shock and immediately before next shock. ROSC was determined from end-tidal CO2, transthoracic impedance (TTI), and patient records. TTI was used to identify chest compressions. Artefact free ECGs were categorized during periods without chest compressions. Episodes without ECG or TTI data or with undeterminable ECG rhythm were excluded. Data were analyzed using descriptive statistics. Of 1657 patients who received 3409 analysable shocks, the rhythm was shockable in 1529 (44.9%) cases 1min post-shock, 13 (0.9%) of which were no longer shockable immediately prior to next possible shock. Of these, three had converted to asystole, seven to PEA and three to ROSC. CONCLUSION While a shockable rhythm 1min post-shock was present also immediately before next possible defibrillation attempt in most cases, three patients had ROSC. Studies are needed to document if moving the pre-shock rhythm analysis will increase shocks delivered to organized rhythms, and if it will increase shock success and survival.

Defibrillation success during different phases of the mechanical chest compression cycle

INTRODUCTION Animal studies indicate higher termination of VF/VT (TOF) rates after shocks delivered during the decompression phase of the compression cycle for manual and mechanical CPR. We investigated TOF for shocks delivered in different compression cycle phases during load distributing band (LDB) mechanical CPR in the CIRC trial. METHODS Shocks were retrospectively categorized as delivered during the compression, decompression, or relaxation phase of LDB compressions using transthoracic impedance data. Shocks delivered when the LDB device was paused, were used as controls. The first shock and the first up-to-three shocks (first shocks plus shocks two and three if given) from patients with initial VF/VT and LDB CPR prior to shock were grouped according to compression cycle phase. TOF rates for these groups versus the control group were analyzed using logistic regression for first shocks and the general estimating equations (GEE) model for the up-to-three shocks. Adjustments were made for bystander CPR, witnessed arrest, defibrillator shock energy and transthoracic impedance. RESULTS Among 244 first shocks and 685 up-to-three shocks TOF success rates were lower (p<0.05 and p<0.02) for shocks given during the compression phase (72% and 71% respectively) than for control shocks given during compression pauses (86% and 82% respectively). Decompression and relaxation phase shocks had TOF rates not different from the controls. CONCLUSION Shocks delivered in the compression phase of LDB chest compressions had lower TOF rates than shocks delivered while pausing the LDB device. More research is needed to see how defibrillation during chest compressions affect ROSC and survival.

Chest compression duration influences outcome between integrated load-distributing band and manual CPR during cardiac arrest

The Circulation Improving Resuscitation Care (CIRC) Trial found equivalent survival in adult out‐of‐hospital cardiac arrest (OHCA) patients who received integrated load‐distributing band CPR (iA‐CPR) compared to manual CPR (M‐CPR). We hypothesized that as chest compression duration increased, iA‐CPR provided a survival benefit when compared to M‐CPR.

Observed survival benefit of mild therapeutic hypothermia reanalysing the Circulation Improving Resuscitation Care trial

Mild therapeutic hypothermia is argued being beneficial for outcome after cardiac arrest.