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

doi:10.1016/j.resuscitation.2021.05.027

Resuscitation

Volume 165, August 2021, Pages 31-37

https://doi.org/10.1016/j.resuscitation.2021.05.027 Get rights and content

Abstract

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.

Introduction

Survival rates from out-of-hospital cardiac arrest (OHCA) remain poor,1, 2, 3 creating both a challenge and a significant opportunity for improvement. Current consensus is that high quality cardiopulmonary resuscitation (CPR) comprised of adequate chest compressions with minimal interruptions is important to increase chances of survival after OHCA⁴. Previous studies have focused on the association of outcomes with CPR with regards to compression rate, depth and fraction5, 6, 7, 8, 9 as well as perishock pause, but none have focused on additional metrics that classify care based on compression and ventilation patterns.

Strategies promoted to increase the quality of CPR have included changes in recommended compression to ventilation ratios. The Resuscitation Outcomes Consortium’s (ROC) Trial of Interrupted vs Continuous Compressions (ROC-CCC) did not detect a significant difference in the primary outcome of survival to discharge between two ventilation strategies: the AHA recommended strategy of 30 compressions with a pause for two ventilations (30:2) versus a strategy of continuous compressions (CCC) with asynchronous ventilation given without a pause.¹⁰ However, adherence to intended CPR technique may be an important neglected predictor of success. In the same trial, patients resuscitated with CPR performed with measurably good adherence to either the CCC or 30:2 protocol showed significantly higher survival than patients resuscitated with strategy that deviated from the intended protocol. Consistency and adherence to protocol can serve as a broad signal of overall team dynamics, which along with system performance monitoring and quality oversight are associated with improved outcomes.¹¹

We previously developed an automated software algorithm that uses the length of compression segments (stop minus start times) and the pattern of compression pauses (defined as ≥2 s) to classify treatment as either 30:2, CCC, or Unclassified (i.e. – not fitting either strategy).¹² We have since refined this algorithm after review of unclassified cases in ROC-CCC to better represent and distinguish between the two strategies. In this study, we used this modified algorithm to address two aims: a) Is adherence to an intended strategy associated with improved outcomes? b) How is adherence to an intended strategy affected by the presence or absence of an interventional trial?

Section snippets

Setting and design

This is a retrospective analysis of OOHCA patients enrolled in the Resuscitation Outcomes Consortium (ROC) between 201 1-2 017. During this time, patients were enrolled in either concurrent ROC-CCC and the Amiodarone, Lidocaine, or Placebo Study (ROC-ALPS)¹³ trials, a Registry or the Pragmatic Airway Resuscitation Trial (PART).¹⁴ Institutional Review Boards of participating institutions approved the parent studies under federal Exception from Informed Consent rules (21 CFR 50.24).

For this

Results

Of the 26,810 patients who were included in this analysis 10,942 (40.8%) had an intended CPR strategy of 30:2 and 15,868 (59.2%) had an intended CPR strategy of CCC. Across the two intended compression strategies, patients significantly differed in witness status and bystander CPR status (both p < 0.05, Table 2). Expectedly, patients with intended CCC strategy had higher mean CCF (0.87 vs 0.80), higher median compression segment length (83.2 s vs 42.8 s) and lower number of pauses per minute

Discussion

Our analysis demonstrates that when adhered to, intended strategy CCC had significantly lower survival OR (95%CI) = 0.72 (0.64, 0.81) while intended strategy 30:2 had higher survival, OR (95%CI) = 1.05 (0.90, 1.22). Although unadjusted survival rates were not significantly different between the two intended CPR strategies (both 9.9%), when considered in context of adherence (a potential reflection of quality care), survival differed according to adherence to the intended CPR strategy.

While

Conclusion

Conflicts of interest

Robert Schmicker, Peter Kudenchuk, Jim Christenson, Christian Vaillancourt, Henry Wang and Mohamud Daya reported no conflicts.

Tom Aufderheide is the site Principal Investigator of the Milwaukee site for the ROC grant.

Ahamed Idris has research grants from the National Institutes of Health and the Center for Disease Control and Prevention. He is an unpaid volunteer of the American Heart Association National Emergency Cardiovascular Care Committee and an unpaid volunteer of the Clinical Advisory

Access to data and data analysis

Robert Schmicker had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

CRediT authorship contribution statement

All authors have made substantial contributions to all of the following: (1) the conception and design of the study, or acquisition of data, or analysis and interpretation of data, (2) drafting the article or revising it critically for important intellectual content, (3) final approval of the version to be submitted. RHS takes responsibility for the article as a whole.

Acknowledgements

This study was supported by grant 5R21HL145423-02 from National Heart Lung and Blood Institute. The Resuscitation Outcomes Consortium institutions participating in the studies were supported by a series of cooperative agreements from the NHLBI, including 5U01 HL077863 (University of Washington Data Coordinating Center), HL077866 (Medical College of Wisconsin), HL077867 (University of Washington), HL077871 (University of Pittsburgh), HL077873 (Oregon Health and Science University), HL077881

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Cardiopulmonary Resuscitation: The Importance of the Basics
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Continuous compression with asynchronous ventilation improves CPR prognosis? A meta-analysis from human and animal studies
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Citation Excerpt :
This study was also included in our review. Although continuous compression with asynchronous ventilation did not show obvious advantages, a secondary analysis from another clinical study still supported that more frequent pauses for breaths were associated with better outcomes during CPR [38]. With the longer time of cardiac arrest, tissue storage oxygen was exhausted, and even irreversible damage was caused.
The cardiopulmonary resuscitation (CPR) compression to ventilation strategy remains controversial. We conducted a meta-analysis to compare the outcomes between continuous chest compressions CPR with asynchronous ventilation (CCC-CPR) and interrupted chest compressions CPR with synchronous ventilation (ICC-CPR) in cardiac arrest.
PubMed, Web of Science, Embase, MEDLINE (Ovid/LWW) and the Cochrane Libraries were searched up from inception to July 31, 2022. Human and animal studies comparing CCC-CPR versus ICC-CPR were included. Outcome variables were return of spontaneous circulation (ROSC), time to ROSC, survival to discharge, 1-month survival, survival at 4 h, good neurological function, mean arterial pressure (MAP) and other clinical parameters. Jadad Scale and Newcastle-Ottawa Scale were used to assess the study quality and risk of bias.
The systematic search identified eight studies on humans and twelve studies on animal trials. There were no significant differences in ROSC (odd ratios [OR] 1.07; 95% confidence interval [CI]: 0.86–1.32; P = 0.55), survival to hospital discharge (OR 1.04; 95%CI 0.77–1.42; P = 0.79), 1-month survival (OR 1.07; 95%CI 0.84–1.36; P = 0.57), and good neurological outcome (OR 0.92; 95%CI 0.84–1.01, P = 0.09) between CCC-CPR and ICC-CPR in human studies. In animal trials, CCC-CPR had significantly higher rate of ROSC (OR = 1.81; 95% CI: 0.94–3.49; P = 0.07), survival at 4 h (OR 2.57; 95% CI: 1.16–5.72; P = 0.02) and MAP (mean difference [MD] 0.79, 95% CI: 0.04–1.53; P = 0.04), even though no significant differences in ROSC time, arterial potential of hydrogen (pH) and partial tension of carbon dioxide (PaCO2).
CCC-CPR did not show superiority in human outcomes compared with ICC-CPR, but its effect value was significantly increased in animal experiments. We should take the positive outcomes from animals and apply them to human models, and more physiological mechanisms need to be confirmed in CPR patients with different compression-ventilation strategies to improve the prognosis of cardiac arrest.
The association of race with CPR quality following out-of-hospital cardiac arrest
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Citation Excerpt :
In this study, 59% of black patients were treated by agencies with 30:2 as their intended strategy. Our previous research showed that a higher rate of noncompliance to 30:2 is associated with lower survival19 while several studies have shown higher compliance to rate is associated with improved survival.16 Along with no differences in depth or pre-shock pause compliance, these counteracting effects could be a major reason why we observed no survival difference between white and black patients in this cohort.21
Previous studies have shown racial disparities in outcomes after out-of-hospital cardiac arrest. Although several treatment factors may account for these differences, there is limited information regarding differences in CPR quality and its effect on survival in underrepresented racial populations.
We conducted a secondary analysis of data from patients enrolled in the Pragmatic Airway Resuscitation Trial (PART). We calculated compliance rates with AHA 2015 high quality CPR metrics as well as compliance to intended CPR strategy (30:2 or continuous chest compression) based on the protocol in place for the first responding EMS agency. The primary analysis used general estimating equations logistic regression to examine differences between black and white patients based on EMS-assessed race after adjustment for potential confounders. Sensitivity analyses examined differences using alternate race definitions.
There were 3004 patients enrolled in PART of which 1734 had > 2 minutes of recorded CPR data and an EMS-assessed race (1003 white, 555 black, 176 other). Black patients had higher adjusted odds of compression rate compliance (OR: 1.36, 95% CI: 1.02–1.81) and lower adjusted odds of intended CPR strategy compliance (OR: 0.78, 95% CI: 0.63–0.98) compared to white patients. Of 974 transported to the hospital, there was no difference in compliance metric estimates based on ED-reported race.
Compression rate compliance was higher in black patients however compliance with intended strategy was lower based on EMS-assessed race. The remaining metrics showed no difference suggesting that CPR quality differences are not important contributors to the observed outcome disparities by race.
Intentional interruptions during compression only CPR: A way to increase adherence to CPR and compressions’ quality?
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“Head Up CPR” Is Not Ready for Widespread Adoption
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Bag-Valve-Mask Ventilation and Survival From Out-of-Hospital Cardiac Arrest: A Multicenter Study
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Clinical paperCPR compression strategy 30:2 is difficult to adhere to, but has better survival than continuous chest compressions when done correctly

Abstract

Background

Methods

Results

Conclusion

Introduction

Section snippets

Setting and design

Results

Discussion

Conclusion

Conflicts of interest

Access to data and data analysis

CRediT authorship contribution statement

Acknowledgements

Resuscitation

Resuscitation

Resuscitation

Resuscitation

Resuscitation

Resuscitation

Resuscitation

2014 Cardiac Arrest Registry to Enhance Survival (CARES) National Summary Report

Regional variation in out-of-hospital cardiac arrest incidence and outcome

JAMA

Part 5: Adult Basic Life Support and Cardiopulmonary Resuscitation Quality: 2015 American Heart Association Guidelines Update for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

Circulation

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