Recurrence of ventricular fibrillation in out-of-hospital cardiac arrest: Clinical evidence and underlying ionic mechanisms.

Defibrillation remains the optimal therapy for terminating ventricular fibrillation (VF) in out-of-hospital cardiac arrest (OHCA) patients, with reported shock success rates of ∼90%. A key persistent challenge, however, is the high rate of VF recurrence (∼50-80%) seen during post-shock cardiopulmonary resuscitation (CPR). Studies have shown that the incidence and time spent in recurrent VF are negatively associated with neurologically-intact survival. Recurrent VF also results in the administration of extra shocks at escalating energy levels, which can cause cardiac dysfunction. Unfortunately, the mechanisms underlying recurrent VF remain poorly understood. In particular, the role of chest-compressions (CC) administered during CPR in mediating recurrent VF remains controversial. In this review, we first summarize the available clinical evidence for refibrillation occurring during CPR in OHCA patients, including the postulated contribution of CC and non-CC related pathways. Next, we examine experimental studies highlighting how CC can re-induce VF via direct mechano-electric feedback. We postulate the ionic mechanisms involved by comparison with similar phenomena seen in commotio cordis. Subsequently, the hypothesized contribution of partial cardiac reperfusion (either as a result of CC or CC independent organized rhythm) in re-initiating VF in a globally ischaemic heart is examined. An overview of the proposed ionic mechanisms contributing to VF recurrence in OHCA during CPR from a cellular level to the whole heart is outlined. Possible therapeutic implications of the proposed mechanistic theories for VF recurrence in OHCA are briefly discussed.

Higher resuscitation guideline adherence in paramedics with use of real-time ventilation feedback during simulated out-of-hospital cardiac arrest: A randomised controlled trial.

OBJECTIVES: To investigate whether real-time ventilation feedback would improve provider adherence to ventilation guidelines. DESIGN: Non-blinded randomised controlled simulation trial. SETTING: One Emergency Medical Service trust in Copenhagen. PARTICIPANTS: 32 ambulance crews consisting of 64 on-duty basic or advanced life support paramedics from Copenhagen Emergency Medical Service. INTERVENTION: Participant exposure to real-time ventilation feedback during simulated out-of-hospital cardiac arrest. MAIN OUTCOME MEASURES: The primary outcome was ventilation quality, defined as ventilation guideline-adherence to ventilation rate (8-10 bpm) and tidal volume (500-600 ml) delivered simultaneously. RESULTS: The intervention group performed ventilations in adherence with ventilation guideline recommendations for 75.3% (Interquartile range (IQR) 66.2%-82.9%) of delivered ventilations, compared to 22.1% (IQR 0%-44.0%) provided by the control group. When controlling for participant covariates, adherence to ventilation guidelines was 44.7% higher in participants receiving ventilation feedback. Analysed separately, the intervention group performed a ventilation guideline-compliant rate in 97.4% (IQR 97.1%-100%) of delivered ventilations, versus 66.7% (IQR 40.9%-77.9%) for the control group. For tidal volume compliance, the intervention group reached 77.5% (IQR 64.9%-83.8%) of ventilations within target compared to 53.4% (IQR 8.4%-66.7%) delivered by the control group. CONCLUSIONS: Real-time ventilation feedback increased guideline compliance for both ventilation rate and tidal volume (combined and as individual parameters) in a simulated OHCA setting. Real-time feedback has the potential to improve manual ventilation quality and may allow providers to avoid harmful hyperventilation.

Corrigendum to "Higher resuscitation guideline adherence in paramedics with use of real-time ventilation feedback during simulated out-of-hospital cardiac arrest: A randomised controlled trial" [Resuscitation Plus 5 (2021) 100082].

[This corrects the article DOI: 10.1016/j.resplu.2021.100082.].

Effect of Amplitude Spectral Area on Termination of Fibrillation and Outcomes in Pediatric Cardiac Arrest.

Background Amplitude spectral area (AMSA) predicts termination of fibrillation (TOF) with return of spontaneous circulation (ROSC) and survival in adults but has not been studied in pediatric cardiac arrest. We characterized AMSA during pediatric cardiac arrest from a Pediatric Resuscitation Quality Collaborative and hypothesized that AMSA would be associated with TOF and ROSC. Methods and Results Children aged <18 years with cardiac arrest and ventricular fibrillation were studied. AMSA was calculated for 2 seconds before shock and averaged for each subject (AMSA-avg). TOF was defined as termination of ventricular fibrillation 10 seconds after defibrillation to any non-ventricular fibrillation rhythm. ROSC was defined as >20 minutes without chest compressions. Univariate and multivariable logistic regression analyses controlling for weight, current, and illness category were performed. Primary end points were TOF and ROSC. Secondary end points were 24-hour survival and survival to discharge. Between 2015 and 2019, 50 children from 14 hospitals with 111 shocks were identified. In univariate analyses AMSA was not associated with TOF and AMS-Aavg was not associated with ROSC. Multivariable logistic regression showed no association between AMSA and TOF but controlling for defibrillation average current and illness category, there was a trend to significant association between AMSA-avg and ROSC (odds ratio, 1.10 [1.00‒1.22] P=0.058). There was no significant association between AMSA-avg and 24-hour survival or survival to hospital discharge. Conclusions In pediatric patients, AMSA was not associated with TOF, whereas AMSA-avg had a trend to significance for association in ROSC, but not 24-hour survival or survival to hospital discharge. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02708134.

Real-Time Cardiopulmonary Resuscitation Feedback and Targeted Training Improve Chest Compression Performance in a Cohort of International Healthcare Providers.

BACKGROUND: Optimal cardiopulmonary resuscitation (CPR) performance is the foundation of successful cardiac arrest resuscitation. However, health care providers perform inadequate compressions. Better training techniques and real-time CPR feedback may improve compression performance. OBJECTIVE: We sought to evaluate the impact of a targeted training program combined with real-time defibrillator CPR feedback on chest compression performance in an international cohort of health care providers. METHODS: Physicians, nurses, respiratory therapists, and technicians from 6 hospitals in 5 countries (Taiwan, Singapore, China, Bahrain, and Kuwait) participated in a standardized resuscitation workshop. Chest compression was measured before and after didactics and activation of CPR feedback. Compressions were performed for 1 min on standard CPR manikins placed on a hospital bed and backboard and measured using ZOLL R Series defibrillators. The percentage of compressions meeting target values for depth and rate were compared before and after the workshop and activation of real-time CPR feedback. No depth maximum was defined to allow for mattress compression. RESULTS: Chest compressions were more likely to meet targets for depth (71-95%, odds ratio [OR] 8.61 [95% confidence interval {CI} 4.42-16.77], p < 0.001), rate (41-81%, OR 6.4 [95% CI 4.2-9.8], p < 0.001), and both depth and rate (5-42%, OR 2.4 [95% CI 6.7-22.9], p < 0.001) after the workshop and activation of real-time CPR feedback. CONCLUSIONS: A targeted training intervention combined with real-time CPR feedback improved chest compression performance among health care providers from various countries.

Chest compression release velocity factors during out-of-hospital cardiac resuscitation.

BACKGROUND: Higher chest compression release velocity (CCRV) has been associated with better outcomes after out-of-hospital cardiac arrest (OHCA), and patient factors have been associated with variations in chest wall compliance and compressibility. We evaluated whether patient sex, age, weight, and time in resuscitation were associated with CCRV during pre-hospital resuscitation from OHCA. METHODS: Observational study of prospectively collected OHCA quality improvement data in two suburban EMS agencies in Arizona between 10/1/2008 and 12/31/2016. Subject-level mean CCRV during the first 10 min of compressions was correlated with categorical variables by the Wilcoxon rank-sum test and with continuous variables by the Spearman's rank correlation coefficient. Generalized estimating equation and linear mixed-effect models were used to study the trend of CCRV over time. RESULTS: During the study period, 2535 adult OHCA cases were treated. After exclusion criteria, 1140 cases remained for analysis. Median duration of recorded compressions was 8.70 min during the first 10 min of CPR. An overall decline in CCRV was observed even after adjusting for compression depth. The subject-level mean CCRV was higher for minutes 0-5 than for minutes 5-10 (mean 347.9 mm/s vs. 339.0 mm/s, 95% CI of the difference -12.4 to -5.4, p < 0.0001). Males exhibited a greater mean CCRV compared to females [344.4 mm/s (IQR 307.3-384.6) vs. 331.5 mm/s (IQR 285.3-385.5), p = 0.013]. Mean CCRV was negatively correlated with age and positively correlated with patient weight. CONCLUSION: CCRV declines significantly over the course of resuscitation. Patient characteristics including male sex, younger age, and increased weight were associated with a higher CCRV.

The impact of real-time chest compression feedback increases with application of the 2015 guidelines.

BACKGROUND: Cardiac arrest survival depends upon chest compression quality. Real-time audiovisual feedback may improve compression guideline adherence, particularly with the more specific 2015 guidelines. METHODS: Subjects included healthcare providers from multiple U.S. hospitals. Compression rate and depth were recorded using standard manikins and real-time audiovisual feedback defibrillators (ZOLL R Series). Subjects were enrolled before (n = 756) and after (n = 995) release of the 2015 guidelines, which define narrower compression targets. Subjects performed 2 min of continuous compressions before and after activation of feedback. The percentage of compressions meeting appropriate rate/depth targets was determined before and after release of the 2015 guidelines. RESULTS: An increase in compression guideline adherence was observed with use of feedback before [68.7% to 96.3%, p < .001] and after [16.6% to 94.1%, p < .001] release of the 2015 guidelines. The proportion of subjects requiring feedback to achieve adherence was higher for the 2015 guidelines [28.6% vs. 78.5%, OR 9.12, 95% CI 7.33-11.35, p < .001]. CONCLUSIONS: The use of real-time audiovisual feedback increases adherence to chest compression guidelines, particularly with application of the narrower 2015 guidelines targets for compression depth and rate.

Quantification of ventilation volumes produced by compressions during emergency department cardiopulmonary resuscitation.

BACKGROUND: Clinical investigations have shown improved outcomes with primary compression cardiopulmonary resuscitation strategies. It is unclear whether this is a result of passive ventilation via chest compressions, a low requirement for any ventilation during the early aspect of resuscitation or avoidance of inadvertent over-ventilation. OBJECTIVES: To quantify whether chest compressions with guideline-compliant depth (>2 in) produce measurable and substantial ventilation volumes during emergency department resuscitation of out-of-hospital cardiac arrest. METHODS: This was a prospective, convenience sampling of adult non-traumatic out-of-hospital cardiac arrest patients receiving on-going cardiopulmonary resuscitation in an academic emergency department from June 1, 2011 to July 30, 2013. Cardiopulmonary resuscitation quality files were analyzed using R-Series defibrillator/monitors (ZOLL Medical) and ventilation data were measured using a Non-Invasive Cardiac Output monitor (Philips/Respironics, Wallingford, CT). RESULTS: cardiopulmonary resuscitation quality data were analyzed from 21 patients (17 males, median age 59). The median compression depth was 2.2 in (IQR = 1.9, 2.5) and the median chest compression fraction was 88.4% (IQR = 82.2, 94.1). We were able to discern 580 ventilations that occurred during compressions. The median passive tidal volume recorded during compressions was 7.5 ml (IQR 3.5, 12.6). While the highest volume recorded was 45.8 ml, 81% of the measured tidal volumes were <20 ml. CONCLUSION: Ventilation volume measurements during emergency department cardiopulmonary resuscitation after out-of-hospital cardiac arrest suggest that chest compressions alone, even those meeting current guideline recommendations for depth, do not provide physiologically significant tidal volumes.

Characterization of Pediatric In-Hospital Cardiopulmonary Resuscitation Quality Metrics Across an International Resuscitation Collaborative.

OBJECTIVES: Pediatric in-hospital cardiac arrest cardiopulmonary resuscitation quality metrics have been reported in few children less than 8 years. Our objective was to characterize chest compression fraction, rate, depth, and compliance with 2015 American Heart Association guidelines across multiple pediatric hospitals. DESIGN: Retrospective observational study of data from a multicenter resuscitation quality collaborative from October 2015 to April 2017. SETTING: Twelve pediatric hospitals across United States, Canada, and Europe. PATIENTS: In-hospital cardiac arrest patients (age < 18 yr) with quantitative cardiopulmonary resuscitation data recordings. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: There were 112 events yielding 2,046 evaluable 60-second epochs of cardiopulmonary resuscitation (196,669 chest compression). Event cardiopulmonary resuscitation metric summaries (median [interquartile range]) by age: less than 1 year (38/112): chest compression fraction 0.88 (0.61-0.98), chest compression rate 119/min (110-129), and chest compression depth 2.3 cm (1.9-3.0 cm); for 1 to less than 8 years (42/112): chest compression fraction 0.94 (0.79-1.00), chest compression rate 117/min (110-124), and chest compression depth 3.8 cm (2.9-4.6 cm); for 8 to less than 18 years (32/112): chest compression fraction 0.94 (0.85-1.00), chest compression rate 117/min (110-123), chest compression depth 5.5 cm (4.0-6.5 cm). "Compliance" with guideline targets for 60-second chest compression "epochs" was predefined: chest compression fraction greater than 0.80, chest compression rate 100-120/min, and chest compression depth: greater than or equal to 3.4 cm in less than 1 year, greater than or equal to 4.4 cm in 1 to less than 8 years, and 4.5 to less than 6.6 cm in 8 to less than 18 years. Proportion of less than 1 year, 1 to less than 8 years, and 8 to less than 18 years events with greater than or equal to 60% of 60-second epochs meeting compliance (respectively): chest compression fraction was 53%, 81%, and 78%; chest compression rate was 32%, 50%, and 63%; chest compression depth was 13%, 19%, and 44%. For all events combined, total compliance (meeting all three guideline targets) was 10% (11/112). CONCLUSIONS: Across an international pediatric resuscitation collaborative, we characterized the landscape of pediatric in-hospital cardiac arrest chest compression quality metrics and found that they often do not meet 2015 American Heart Association guidelines. Guideline compliance for rate and depth in children less than 18 years is poor, with the greatest difficulty in achieving chest compression depth targets in younger children.

Cardiac rhythm analysis during ongoing cardiopulmonary resuscitation using the Analysis During Compressions with Fast Reconfirmation technology.

BACKGROUND: Pauses in chest compressions (CCs) have a negative association with survival from cardiac arrest. Electrocardiographic (ECG) rhythm analysis and defibrillator charging are significant contributors to CC pauses. OBJECTIVE: Accuracy of the Analysis During Compressions with Fast Reconfirmation (ADC-FR) algorithm, which features automated rhythm analysis and charging during CCs to reduce CC pauses, was retrospectively determined in a large database of ECGs from 2701 patients with out-of-hospital cardiac arrest. METHODS: The ADC-FR algorithm generated a total of 7264 advisories, of which 3575 were randomly assigned to a development data set and 3689 to a test data set. With ADC-FR, a high-pass digital filter is used to remove CC artifacts, while the underlying ECG rhythm is automatically interpreted. When CCs are paused at the end of the 2-minute cardiopulmonary resuscitation interval, a 3-second reconfirmation analysis is performed using the artifact-free ECG to confirm the shock/no-shock advisory. The sensitivity and specificity of the ADC-FR algorithm in correctly identifying shockable/nonshockable rhythms during CCs were calculated. RESULTS: In both data sets, the accuracy of the ADC-FR algorithm for each ECG rhythm exceeded the recommended performance goals, which apply to a standard artifact-free ECG analysis. Sensitivity and specificity were 97% and 99%, respectively, for the development data set and 95% and 99% for the test data set. CONCLUSION: The ADC-FR algorithm is highly accurate in discriminating shockable and nonshockable rhythms and can be used to reduce CC pauses.

Chest compression release velocity: Association with survival and favorable neurologic outcome after out-of-hospital cardiac arrest.

PURPOSE: We evaluated the association between chest compression release velocity (CCRV) and outcomes after out-of-hospital cardiac arrest (OHCA). MATERIALS AND METHODS: CPR quality was measured using a defibrillator with accelerometer-based technology (E Series, ZOLL Medical) during OHCA resuscitations by 2 EMS agencies in Arizona between 10/2008 and 06/2013. All non-EMS-witnessed adult (≥ 18 years) arrests of presumed cardiac etiology were included. The association between mean CCRV (assessed as an appropriate measure of central tendency) and both survival to hospital discharge and neurologic outcome (Cerebral Performance Category score = 1 or 2) was analyzed using multivariable logistic regression to control for known and potential confounders and multiple imputation to account for missing data. RESULTS: 981 OHCAs (median age 68 years, 65% male, 11% survival to discharge) were analyzed with 232 (24%) missing CPR quality data. All-rhythms survival varied significantly with CCRV [fast (≥ 400 mm/s) = 18/79 (23%); moderate (300-399.9 mm/s) = 50/416 (12%); slow (<300 mm/s) 17/255 (7%); p < 0.001], as did favorable neurologic outcome [fast = 14/79 (18%); moderate = 43/415 (10%); slow = 11/255 (4%); p < 0.001]. Fast CCRV was associated with increased survival compared to slow [adjusted odds ratio (aOR) 4.17 (95% CI: 1.61, 10.82) and moderate CCRV [aOR 3.08 (1.39, 6.83)]. Fast CCRV was also associated with improved favorable neurologic outcome compared to slow [4.51 (1.57, 12.98)]. There was a 5.2% increase in the adjusted odds of survival for each 10mm/s increase in CCRV [aOR 1.052 (1.001, 1.105)]. CONCLUSION: CCRV was independently associated with improved survival and favorable neurologic outcome at hospital discharge after adult OHCA.

Amplitude-spectral area and chest compression release velocity independently predict hospital discharge and good neurological outcome in ventricular fibrillation out-of-hospital cardiac arrest.

OBJECTIVE: In out-of-hospital cardiac arrest (OHCA) with ventricular fibrillation (VF) the frequency-based waveform characteristic, amplitude-spectral area (AMSA) is associated with hospital discharge and good neurological outcome, yet AMSA is also known to increase in response to chest compressions (CC). In addition to rate and depth, well performed CC provides good chest recoil without leaning, reflected in the release velocity (RV). We hypothesized that AMSA is associated with hospital discharge and good neurological outcome independent of CC quality. METHODS: OHCA patients (age ≥ 18), with initial rhythm of VF from an Utstein-Style database were analyzed. AMSA was measured prior to each shock, and averaged for each subject (AMSA-avg). Primary endpoint was hospital discharge and secondary endpoint was a good neurological outcome. Univariate and stepwise multivariable logistic regression, and receiver-operator-characteristic (ROC) analyses were performed. Factors analyzed were age, sex, witnessed status, time from dispatch to monitor/defibrillator application, number of shocks, first shock AMSA (AMSA1), AMSA-avg, averaged pre-shock pause, CC rate, depth, and RV. RESULTS: 140 subjects were analyzed. Hospital discharge was 31% and with good neurological outcome in 24% (77% of those discharged). AMSA-avg (p < 0.001), RV (p = 0.002), and age (p = 0.029) were independently associated with hospital discharge, with a non-significant trend for witnessed status (p = 0.069), with AUC = 0.846 for the multivariate model. For good neurological outcome, AMSA-avg (p = 0.001) and RV (p = 0.001) remained independently significant, with AUC = 0.782. CONCLUSION: In OHCA with an initial rhythm of VF, AMSA-avg and CC RV are both highly and independently associated with hospital discharge and good neurological outcome.

Measuring and improving cardiopulmonary resuscitation quality inside the emergency department.

AIM OF STUDY: To evaluate CPR quality during cardiac resuscitation attempts in an urban emergency department (ED) and determine the influence of the combination of scenario-based training, real-time audiovisual feedback (RTAVF), and post-event debriefing on CPR quality. METHODS: CPR quality was recorded using an R Series monitor-defibrillator (ZOLL Medical) during the treatment of adult cardiac arrest patients. Phase 1 (P1; 11/01/2010-11/15/2012) was an observation period of CPR quality. Phase 2 (P2; 11/15/2012-11/08/2013) was after a 60-min psychomotor skills CPR training and included RTAVF and post-event debriefing. RESULTS: A total of 52 cardiac arrest patients were treated in P1 (median age 56 yrs, 63.5% male) and 49 in P2 (age 60 yrs, 83.7% male). Chest compression (CC) depth increased from 46.7 ± 3.8mm in P1 to 61.6 ± 2.8mm in P2 (p < 0.001), with the percentage of CC ≥ 51 mm increasing from 30.6% in P1 to 87.4% in P2 (p < 0.001). CC release velocity increased from 314 ± 25 mm/s in P1 to 442 ± 20 mm/s in P2 (p < 0.001). No significant differences were identified in CC fraction (84.3% P1 vs. 88.4% P2, p = 0.1), CC rate (125 ± 3 cpm P1 vs. 125 ± 3 cpm P2, p = 0.7), or pre-shock pause (9.7s P1 vs. 5.9s P2, p = 0.5), though CC fraction and pre-shock pause were within guideline recommendations. CONCLUSION: Implementation of the bundle of scenario-based training, real-time audiovisual CPR feedback, and post-event debriefing was associated with improved CPR quality and compliance with CPR guidelines in this urban teaching emergency department.

The association between chest compression release velocity and outcomes from out-of-hospital cardiac arrest.

BACKGROUND: Previous studies have demonstrated significant relationships between cardiopulmonary resuscitation (CPR) quality metrics and survival to hospital discharge from out-of-hospital cardiac arrest (OHCA). Recently, it has been suggested that a new metric, chest compression release velocity (CCRV), may be associated with improved survival from OHCA. METHODS AND RESULTS: We performed a retrospective review of all treated adult OHCA occurring over a two year period beginning January 1, 2012. CPR metrics were abstracted from accelerometer measurements during each resuscitation. Multivariable regression analysis was used to examine the impact of CCRV on survival to hospital discharge. Secondary outcome measures were the impact of CCRV on return of spontaneous circulation (ROSC) and neurologically intact survival (MRS ≤ 3). Among 1800 treated OHCA, 1137 met inclusion criteria. The median (IQR) age was 71.6 (60.6, 82.3) with 724 (64%) being male. The median (IQR) CCRV (mm/s) amongst 96 survivors was 334.5 (300.0, 383.2) compared to 304.0 (262.6, 354.1) in 1041 non survivors (p < 0.001). When adjusted for Utstein variables, the odds of survival to hospital discharge for each 10 mm/s increase in CCRV was 1.02 (95% CI: 0.98, 1.06). Similarly the odds of ROSC and neurologically intact survival were 1.01 (95% CI: 0.99, 1.03) and 1.02 (95% CI: 0.98, 1.06), respectively. CONCLUSIONS: When adjusted for Utstein variables, CCRV was not significantly associated with outcomes from OHCA. Further research in other EMS systems is required to clarify the potential impact of this variable on OHCA survival.

Association of amplitude spectral area of the ventricular fibrillation waveform with survival of out-of-hospital ventricular fibrillation cardiac arrest.

BACKGROUND: Previous investigations of out-of-hospital cardiac arrest (OHCA) have shown that the waveform characteristic amplitude spectral area (AMSA) can predict successful defibrillation and return of spontaneous circulation (ROSC) but has not been studied previously for survival. OBJECTIVES: To determine whether AMSA computed from the ventricular fibrillation (VF) waveform is associated with pre-hospital ROSC, hospital admission, and hospital discharge. METHODS: Adults with witnessed OHCA and an initial rhythm of VF from an Utstein style database were studied. AMSA was measured prior to each shock and averaged for each subject (AMSA-avg). Factors such as age, sex, number of shocks, time from dispatch to monitor/defibrillator application, first shock AMSA, and AMSA-avg that could predict pre-hospital ROSC, hospital admission, and hospital discharge were analyzed by logistic regression. RESULTS: Eighty-nine subjects (mean age 62 ± 15 years) with a total of 286 shocks were analyzed. AMSA-avg was associated with pre-hospital ROSC (p = 0.003); a threshold of 20.9 mV-Hz had a 95% sensitivity and a 43.4% specificity. Additionally, AMSA-avg was associated with hospital admission (p < 0.001); a threshold of 21 mV-Hz had a 95% sensitivity and a 54% specificity and with hospital discharge (p < 0.001); a threshold of 25.6 mV-Hz had a 95% sensitivity and a 53% specificity. First-shock AMSA was also predictive of pre-hospital ROSC, hospital admission, and discharge. Time from dispatch to monitor/defibrillator application was associated with hospital admission (p = 0.034) but not pre-hospital ROSC or hospital discharge. CONCLUSIONS: AMSA is highly associated with pre-hospital ROSC, survival to hospital admission, and hospital discharge in witnessed VF OHCA. Future studies are needed to determine whether AMSA computed during resuscitation can identify patients for whom continuing current resuscitation efforts would likely be futile.

Resumption of chest compressions after successful defibrillation and risk for recurrence of ventricular fibrillation in out-of-hospital cardiac arrest.

BACKGROUND: Prior investigation of out-of-hospital cardiac arrest has raised the concern that ventricular fibrillation (VF) recurrence may be triggered by chest compression (CC) resumption. We investigated predictors of VF recurrence after defibrillation, including timing of CC resumption. METHODS AND RESULTS: Patients with witnessed out-of-hospital cardiac arrest and initial rhythm of VF from an Utstein-style database were analyzed. For each shock that defibrillated VF, CC resumption and VF recurrence times were determined. Shocks were classified according to postshock rhythm. Factors (age, sex, time from dispatch to monitor/defibrillator application, and CC resumption) that could predict VF recurrence were analyzed. CC resumption was categorized into groups: CC1, 1 to 5 seconds; CC2, 6 to 10 seconds; CC3, 11 to 30 seconds; and CC4, >30 seconds. Eighty-eight subjects were analyzed, with a total of 285 shocks, with 226 shocks that achieved asystole (n=102), organized rhythm (n=120), or monomorphic ventricular tachycardia (n=4). After a successful shock, CC resumption occurred at a median (interquartile range) of 8 (5-18) seconds. VF recurred after 166 shocks (74%) and recurred within 30 seconds in 69 shocks. There was no significant relationship between VF recurrence and factors analyzed including CC resumption time, nor stratified by postshock rhythm. The hazard ratios (HRs) for VF recurrence within 30 seconds for later CC groups (CC2, CC3, and CC4) relative to early CC resumption (CC1) were as follows: HR(CC2)=1.05 (P=0.9); HR(CC3)=1.75 (P=0.1); and HR(CC4)=0.67 (P=0.4). CONCLUSIONS: VF recurrence within 30 seconds of a defibrillatory shock was not dependent on timing of CC resumption in patients with witnessed arrest and initial rhythm of VF.

Chest compression depth and survival in out-of-hospital cardiac arrest.

AIM: Outcomes from out-of-hospital cardiac arrest (OHCA) may improve if rescuers perform chest compressions (CCs) deeper than the previous recommendation of 38-51mm and consistent with the 2010 AHA Guideline recommendation of at least 51mm. The aim of this study was to assess the relationship between CC depth and OHCA survival. METHODS: Prospective analysis of CC depth and outcomes in consecutive adult OHCA of presumed cardiac etiology from two EMS agencies participating in comprehensive CPR quality improvement initiatives. ANALYSIS: Multivariable logistic regression to calculate adjusted odds ratios (aORs) for survival to hospital discharge and favorable functional outcome. RESULTS: Among 593 OHCAs, 136 patients (22.9%) achieved return of spontaneous circulation, 63 patients (10.6%) survived and 50 had favorable functional outcome (8.4%). Mean CC depth was 49.8±11.0mm and mean CC rate was 113.9±18.1CCmin(-1). Mean depth was significantly deeper in survivors (53.6mm, 95% CI: 50.5-56.7) than non-survivors (48.8mm, 95% CI: 47.6-50.0). Each 5mm increase in mean CC depth significantly increased the odds of survival and survival with favorable functional outcome: aORs were 1.29 (95% CI 1.00-1.65) and 1.30 (95% CI 1.00-1.70) respectively. CONCLUSION: Deeper chest compressions were associated with improved survival and functional outcome following OHCA. Our results suggest that adhering to the 2010 AHA Guideline-recommended depth of at least 51mm could improve outcomes for victims of OHCA.

The influence of scenario-based training and real-time audiovisual feedback on out-of-hospital cardiopulmonary resuscitation quality and survival from out-of-hospital cardiac arrest.

STUDY OBJECTIVE: We assess whether an initiative to optimize out-of-hospital provider cardiopulmonary resuscitation (CPR) quality is associated with improved CPR quality and increased survival from out-of-hospital cardiac arrest. METHODS: This was a before-after study of consecutive adult out-of-hospital cardiac arrest. Data were obtained from out-of-hospital forms and defibrillators. Phase 1 included 18 months with real-time audiovisual feedback disabled (October 2008 to March 2010). Phase 2 included 16 months (May 2010 to September 2011) after scenario-based training of 373 professional rescuers and real-time audiovisual feedback enabled. The effect of interventions on survival to hospital discharge was assessed with multivariable logistic regression. Multiple imputation of missing data was used to analyze the effect of interventions on CPR quality. RESULTS: Analysis included 484 out-of-hospital cardiac arrest patients (phase 1 232; phase 2 252). Median age was 68 years (interquartile range 56-79); 66.5% were men. CPR quality measures improved significantly from phase 1 to phase 2: Mean chest compression rate decreased from 128 to 106 chest compressions per minute (difference -23 chest compressions; 95% confidence interval [CI] -26 to -19 chest compressions); mean chest compression depth increased from 1.78 to 2.15 inches (difference 0.38 inches; 95% CI 0.28 to 0.47 inches); median chest compression fraction increased from 66.2% to 83.7% (difference 17.6%; 95% CI 15.0% to 20.1%); median preshock pause decreased from 26.9 to 15.5 seconds (difference -11.4 seconds; 95% CI -15.7 to -7.2 seconds), and mean ventilation rate decreased from 11.7 to 9.5/minute (difference -2.2/minute; 95% CI -3.9 to -0.5/minute). All-rhythms survival increased from phase 1 to phase 2 (20/231, 8.7% versus 35/252, 13.9%; difference 5.2%; 95% CI -0.4% to 10.8%), with an adjusted odds ratio of 2.72 (95% CI 1.15 to 6.41), controlling for initial rhythm, witnessed arrest, age, minimally interrupted cardiac resuscitation protocol compliance, and provision of therapeutic hypothermia. Witnessed arrests/shockable rhythms survival was 26.3% (15/57) for phase 1 and 55.6% (20/36) for phase 2 (difference 29.2%; 95% CI 9.4% to 49.1%). CONCLUSION: Implementation of resuscitation training combined with real-time audiovisual feedback was independently associated with improved CPR quality, an increase in survival, and favorable functional outcomes after out-of-hospital cardiac arrest.

CPR variability during ground ambulance transport of patients in cardiac arrest.

AIM OF STUDY: High-quality CPR is associated with improved outcomes from out-of-hospital cardiac arrest (OHCA). The purpose of this investigation was to compare the quality of CPR provided at the prehospital scene, during ambulance transport, and during the early minutes in the emergency department (ED). METHODS: A prospective observational review of consecutive adult patients with non-traumatic OHCA was conducted between September 2008 and February 2010. Patients with initiation of prehospital CPR were included as part of a statewide cardiac resuscitation quality improvement program. A monitor-defibrillator with accelerometer-based CPR measurement capability (E-series, ZOLL Medical) was utilized. CPR quality measures included variability in chest compression (CC) depth and rate, mean depth and rate, and the CC fraction. Variability of CC was defined as the mean of minute-to-minute standard deviation in CC depth or rate. CC fraction was defined as the percent of time that CPR was being performed when appropriate throughout resuscitation. RESULTS: Fifty-seven adult patients with OHCA had electronic CPR data recorded at the scene, in the ambulance, and upon arrival in the ED. Across time periods, there was increased variability in CC depth (scene: 0.20 in.; transport: 0.26 in.; ED: 0.31 in., P<0.01) and rate (scene: 18.2 CC min(-1); transport: 26.1 CC min(-1); ED: 26.3 CC min(-1), P<0.01). The mean CC depth, rate, and the CC fraction did not differ significantly between groups. CONCLUSIONS: There was increased CC variability from the prehospital scene to the ED though there was no difference in mean CC depth, rate, or in CC fraction. The clinical significance of CC variability remains to be determined.