A review of chest compression interruptions during out-of-hospital cardiac arrest and strategies for the future

Artificial intelligence-based evaluation of carotid artery compressibility via point-of-care ultrasound in determining the return of spontaneous circulation during cardiopulmonary resuscitation

AIM

This study introduces RealCAC-Net, an artificial intelligence (AI) system, to quantify carotid artery compressibility (CAC) and determine the return of spontaneous circulation (ROSC) during cardiopulmonary resuscitation.

METHODS

A prospective study based on data from a South Korean emergency department from 2022 to 2023 investigated carotid artery compressibility in adult patients with cardiac arrest using a novel AI model, RealCAC-Net. The data comprised 11,958 training images from 161 cases and 15,080 test images from 134 cases. RealCAC-Net processes images in three steps: TransUNet-based segmentation, the carotid artery compressibility measurement algorithm for improved segmentation and CAC calculation, and CAC-based classification from 0 (indicating a circular shape) to 1 (indicating high compression). The accuracy of the ROSC classification model was tested using metrics such as the dice similarity coefficient, intersection-over-union, precision, recall, and F1 score.

RESULTS

RealCAC-Net, which applied the carotid artery compressibility measurement algorithm, performed better than the baseline model in cross-validation, with an average dice similarity coefficient of 0.90, an intersection-over-union of 0.84, and a classification accuracy of 0.96. The test set achieved a classification accuracy of 0.96 and an F1 score of 0.97, demonstrating its efficacy in accurately identifying ROSC in cardiac arrest situations.

CONCLUSIONS

RealCAC-Net enabled precise CAC quantification for ROSC determination during cardiopulmonary resuscitation. Future research should integrate this AI-enhanced ultrasound approach to revolutionize emergency care.

Intentional interruptions during compression only CPR: A scoping review

Introduction

Out of hospital cardiac arrest (OHCA) remains one of the main causes of death among industrialized countries. The initiation of cardiopulmonary resuscitation (CPR) by laypeople before the arrival of emergency medical services improves survival. Mouth-to-mouth ventilation may constitute a hindering factor to start bystander CPR, while during continuous chest compressions (CCC) CPR quality decreases rapidly. The aim of this scoping review is to examine the existing literature on strategies that investigate the inclusion of intentional pauses during compression-only resuscitation (CO-CPR) to improve the performance in the context of single lay rescuer OHCA.

Methods

The protocol of this Scoping review was prospectively registered in Open Science Framework (https://osf.io/rvn8j). A systematic search of PubMed, Scopus, EMBASE, CINAHL was performed.

Results

Six articles were included. All studies were carried out on simulation manikins and involved a total of 1214 subjects. One study had a multicenter design. Three studies were randomized controlled simulation trials, the rest were prospective randomized crossover studies. The tested protocols were heterogeneous and compared CCC to CO-CPR with intentional interruptions of various length. The most common primary outcome was compressions depth. Compression rate, rescuers' perceived exertion and composite outcomes were also evaluated. Compressions depth and perceived exertion improved in most study groups while compression rate and chest compression fraction remained within guidelines indications.

Conclusions

In simulation studies, the inclusion of intentional interruptions during CO-CPR within the specific scenario of single rescuer bystander CPR during OHCA may improve the rate of compressions with correct depth and lower rate of perceived exertion. Further high-quality research and feasibility and safety of protocols incorporating intentional interruptions during CO-CPR may be justified.

Cardiac Rhythm Changes During Transfer from the Emergency Medical Service to the Emergency Department: A Retrospective Tertiary Single-Center Analysis on Prevalence and Outcomes

BACKGROUND

Out-of-hospital cardiac arrest (OHCA) is a leading cause of death worldwide. Cardiac rhythms of OHCA patients can change during transportation and transfer from emergency medical services (EMS) to the emergency department (ED).

OBJECTIVE

Our objective was to study the prevalence of cardiac rhythm changes during transfer from the EMS to the ED in OHCA patients and the possible association with clinical outcomes.

METHODS

We retrospectively studied adult OHCA patients admitted to the ED between January 2017 and December 2019. The primary outcome was the incidence of cardiac rhythm changes during transfer from EMS to the ED. Secondary outcomes were: ED survival, intensive care unit survival, hospital survival, and maximum Glasgow Coma Scale score during admission.

RESULTS

We included 625 patients, of whom there were 49 (7.8%) in the rhythm change group and 576 in the no rhythm change group. ED survival was significantly lower in the rhythm change group (26.5%) vs. the no rhythm change group (78.5%, p < 0.01).

CONCLUSION

Cardiac rhythm changes can occur in OHCA patients during transfer from EMS to the ED. Our results showed some evidence that these changes are associated with a lower ED survival.

Development of an automatic device performing chest compression and external defibrillation: An animal-based pilot study

BACKGROUND

Automatic chest compression devices (ACCDs) can promote high-quality cardiopulmonary resuscitation (CPR) and are widely used worldwide. Early application of automated external defibrillators (AEDs) along with high-quality CPR is crucial for favorable outcomes in patients with cardiac arrest. Here, we developed an automated CPR (A-CPR) apparatus that combines ACCD and AED and evaluated its performance in a pilot animal-based study.

METHODS

Eleven pigs (n = 5, A-CPR group; n = 6, ACCD CPR and AED [conventional CPR (C-CPR)] group) were enrolled in this study. After 2 min observation without any treatment following ventricular fibrillation induction, CPR with a 30:2 compression/ventilation ratio was performed for 6 min, mimicking basic life support (BLS). A-CPR or C-CPR was applied immediately after BLS, and resuscitation including chest compression and defibrillation, was performed following a voice prompt from the A-CPR device or AED. Hemodynamic parameters, including aortic pressure, right atrial pressure, coronary perfusion pressure, carotid blood flow, and end-tidal carbon dioxide, were monitored during resuscitation. Time variables, including time to start rhythm analysis, time to charge, time to defibrillate, and time to subsequent chest compression, were also measured.

RESULTS

There were no differences in baseline characteristics, except for arterial carbon dioxide pressure (39 in A-CPR vs. 33 in C-CPR, p = 0.034), between the two groups. There were no differences in hemodynamic parameters between the groups. However, time to charge (28.9 ± 5.6 s, A-CPR group; 47.2 ± 12.4 s, C-CPR group), time to defibrillate (29.1 ± 7.2 s, A-CPR group; 50.5 ± 12.3 s, C-CPR group), and time to subsequent chest compression (32.4 ± 6.3 s, A-CPR group; 56.3 ± 10.7 s, C-CPR group) were shorter in the A-CPR group than in the C-CPR group (p = 0.015, 0.034 and 0.02 respectively).

CONCLUSIONS

A-CPR can provide effective chest compressions and defibrillation, thereby shortening the time required for defibrillation.

Impact of Ultrasonography on Chest Compression Fraction and Survival in Patients with Out-of-hospital Cardiac Arrest

INTRODUCTION

Whether ultrasonography (US) contributes to delays in chest compressions and hence a negative impact on survival is uncertain. In this study we aimed to investigate the impact of US on chest compression fraction (CCF) and patient survival.

METHODS

We retrospectively analyzed video recordings of the resuscitation process in a convenience sample of adult patients with non-traumatic, out-of-hospital cardiac arrest. Patients receiving US once or more during resuscitation were categorized as the US group, while the patients who did not receive US were categorized as the non-US group. The primary outcome was CCF, and the secondary outcomes were the rates of return of spontaneous circulation (ROSC), survival to admission and discharge, and survival to discharge with a favorable neurological outcome between the two groups. We also evaluated the individual pause duration and the percentage of prolonged pauses associated with US.

RESULTS

A total of 236 patients with 3,386 pauses were included. Of these patients, 190 received US and 284 pauses were related to US. Longer resuscitation duration was observed in the US group (median, 30.3 vs 9.7 minutes, P<.001). The US group had comparable CCF (93.0% vs 94.3%, P=0.29) with the non-US group. Although the non-US group had a better rate of ROSC (36% vs 52%, P=0.04), the rates of survival to admission (36% vs 48%, P=0.13), survival to discharge (11% vs 15%, P=0.37), and survival with favorable neurological outcome (5% vs 9%, P=0.23) did not differ between the two groups. The pause duration of pulse checks with US was longer than pulse checks alone (median, 8 vs 6 seconds, P=0.02). The percentage of prolonged pauses was similar between the two groups (16% vs 14%, P=0.49).

CONCLUSION

When compared to the non-ultrasound group, patients receiving US had comparable chest compression fractions and rates of survival to admission and discharge, and survival to discharge with a favorable neurological outcome. The individual pause was lengthened related to US. However, patients without US had a shorter resuscitation duration and a better rate of ROSC. The trend toward poorer results in the US group was possibly due to confounding variables and nonprobability sampling. It should be better investigated in further randomized studies.

Pre-charging the defibrillator before rhythm analysis reduces hands-off time in patients with out-of-hospital cardiac arrest with shockable rhythm

AIM

To evaluate the effect of pre-charging the defibrillator before rhythm analysis on hands-off time in patients suffering from out-of-hospital cardiac arrest with shockable rhythm.

METHODS

Pre-charging was implemented in the Emergency Medical Service in the Central Denmark Region in June 2018. Training consisted of hands-on simulation scenarios, e-learning material, and written instructions. Data were extracted from the Danish Cardiac Arrest Registry for a 14-month period spanning the implementation of pre-charging. Patients having received at least one shock were included. Transthoracic impedance data were analysed. We recorded hands-off time and peri-shock pauses for all defibrillation procedures and the total hands-off fraction for all cardiac arrests.

RESULTS

Impedance and outcome data were available for 178 patients. 523 defibrillation procedures were analysed. The pre-charge method was associated with shorter median hands-off time per defibrillation procedure (7.6 (IQR 5.8-9.9) vs. 12.6 (IQR 10-16.4) seconds, p < 0.001) but longer pre-shock pause (4 (IQR 2.7-6.1) vs 1.7 (IQR 1.2-3) seconds, p < 0.001) when compared to the current guideline-recommended defibrillation method. The total hands-off fraction per cardiac arrest was reduced after implementation of the pre-charge method (16.5% vs. 20.4%, p = 0.003). No increase in shocks to non-shockable rhythms or personnel was registered. Patients who received only pre-charge defibrillations had an increased odds ratio of return of spontaneous circulation (aOR 2.91; 95%CI 1.09-7.8, p = 0.03).

CONCLUSION

Pre-charging the defibrillator reduced hands-off time during defibrillation procedures, reduces the total hands-off fraction and may be associated with increased return of spontaneous circulation in out-of-hospital cardiac arrest with shockable rhythm.

The effect of high-dose intramuscular epinephrine on the recovery of spontaneous circulation in an asphyxia-induced cardiac arrest rat model

BACKGROUND

Obtaining vascular access can be challenging during resuscitation following cardiac arrest, and it is particularly difficult and time-consuming in paediatric patients. We aimed to compare the efficacy of high-dose intramuscular (IM) versus intravascular (IV) epinephrine administration with regard to the return of spontaneous circulation (ROSC) in an asphyxia-induced cardiac arrest rat model.

METHODS

Forty-five male Sprague-Dawley rats were used for these experiments. Cardiac arrest was induced by asphyxia, and defined as a decline in mean arterial pressure (MAP) to 20 mmHg. After asphyxia-induced cardiac arrest, the rats were randomly allocated into one of 3 groups (control saline group, IV epinephrine group, and IM epinephrine group). After 540 s of cardiac arrest, cardiopulmonary resuscitation was performed, and IV saline (0.01 cc/kg), IV (0.01 mg/kg, 1:100,000) epinephrine or IM (0.05 mg/kg, 1:100,000) epinephrine was administered. ROSC was defined as the achievement of an MAP above 40 mmHg for more than 1 minute. Rates of ROSC, haemodynamics, and arterial blood gas analysis were serially observed.

RESULTS

The ROSC rate (61.5%) of the IM epinephrine group was less than that in the IV epinephrine group (100%) but was higher than that of the control saline group (15.4%) (log-rank test). There were no differences in MAP between the two groups, but HR in the IM epinephrine group (beta coefficient = 1.02) decreased to a lesser extent than that in the IV epinephrine group with time.

CONCLUSIONS

IM epinephrine induced better ROSC rates compared to the control saline group in asphyxia-induced cardiac arrest, but not compared to IV epinephrine. The IM route of epinephrine administration may be a promising option in an asphyxia-induced cardiac arrest.

Enhancing CPR During Transition From Prehospital to Emergency Department: A QI Initiative

BACKGROUND AND OBJECTIVES

High-quality cardiopulmonary resuscitation (CPR) increases the likelihood of survival of pediatric out-of-hospital cardiac arrest (OHCA). Maintenance of high-quality CPR during transition of care between prehospital and pediatric emergency department (PED) providers is challenging. Our objective for this initiative was to minimize pauses in compressions, in alignment with American Heart Association recommendations, for patients with OHCA during the handoffs from prehospital to PED providers. We aimed to decrease interruptions in compressions during the first 2 minutes of PED care from 17 seconds (baseline data) to 10 seconds over 12 months. Our secondary aims were to decrease the length of the longest pause in compressions to <10 seconds and eliminate encounters in which time to defibrillator pad placement was >120 seconds.

METHODS

Our multidisciplinary team outlined our theory for improvement and designed interventions aimed at key drivers. Interventions included specific roles and responsibilities, CPR handoff choreography, and empowerment of frontline providers. Data were abstracted from video recordings of patients with OHCA receiving manual CPR on arrival.

RESULTS

We analyzed 33 encounters between March 2018 and July 2019. We decreased total interruptions from 17 to 12 seconds during the first 2 minutes and decreased the time of the longest single pause from 14 to 7 seconds. We saw a decrease in variability of time to defibrillator pad placement.

CONCLUSIONS

Implementation of a quality improvement initiative involving CPR transition choreography resulted in decreased interruptions in compressions and decreased variability of time to defibrillator pad placement.

Comparison of standard and over-the-head method of chest compressions during cardiopulmonary resuscitation - a simulation study

Background

Maintaining highly effective cardiopulmonary resuscitation (CPR) can be particularly difficult when artificial ventilation using a bag-valve-mask device, combined with chest compression have to be carried out by one person. The aim of the study is to compare the quality of CPR conducted by one paramedic using chest compression from the patient’s side with compression conducted from the ‘over-the-head’ position.

Methods

The subject of the study were two methods of CPR – ‘standard’ (STD) and ‘over-the-head’ (OTH). The STD method consisted of cycles of 30 chest compressions from the patient’s side, and two attempts at artificial ventilation after moving round to behind the patient’s head. In the OTH method, both compressions and ventilations were conducted from behind the patient’s head.

Results

Both CPR methods were conducted by 38 paramedics working in medical response teams. Statistical analysis was conducted on the data collected, giving the following results: the average time of the interruptions between compression cycles (STD 9.184 s, OTH 7.316 s, p < 0.001); the depth of compression 50–60 mm (STD 50.65%, OTH 60.22%, p < 0.001); the rate of compression 100–120/min. (STD 46.39%, OTH 53.78%, p < 0.001); complete chest wall recoil (STD 84.54%, OTH 91.46%, p < 0.001); correct hand position (STD 99.32%, OTH method 99.66%, p < 0.001). A statistically significant difference was demonstrated in the results to the benefit of the OTH method in the above parameters. The remaining parameters showed no significant differences in comparison to reference values.

Conclusions

The higher quality of CPR in the simulated research using the OTH method by a single person justifies the use of this method in a wider range of emergency interventions.

Retrospective cohort study of hospital variation in airway management during in-hospital cardiac arrest and the association with patient survival: insights from Get With The Guidelines-Resuscitation

IMPORTANCE

The optimal approach to airway management during in-hospital cardiac arrest is unknown.

OBJECTIVE

To describe hospital-level variation in endotracheal intubation during cardiopulmonary resuscitation (CPR) for in-hospital cardiac arrest and the association between hospital use of endotracheal intubation and arrest survival.

DESIGN, SETTING, PARTICIPANTS

Retrospective cohort study of adult patients suffering in-hospital cardiac arrest at Get With The Guidelines-Resuscitation participating hospitals between January, 2000, and December, 2016. Hospitals were categorized into quartiles based on the proportion of in-hospital cardiac arrest patients managed with endotracheal intubation during CPR. Risk-adjusted mixed models with random intercepts were created to assess the association between hospital quartile of in-hospital arrests managed with endotracheal intubation during CPR and survival to hospital discharge.

EXPOSURE

Hospital rate of endotracheal intubation during CPR for in-hospital arrest MAIN OUTCOMES AND MEASURES: Survival to hospital discharge RESULTS: Among 155,252 patients suffering in-hospital cardiac arrest at 656 hospitals, 69.7% of patients received endotracheal intubation during CPR and overall survival to discharge was 24.8%. At the hospital level, the median rate of endotracheal intubation use was 71.2% (interquartile range, 63.6 to 78.1%; range, 26.6 to 100%). We found a strong inverse association between hospital rate of endotracheal intubation and survival to discharge (risk-adjusted odds ratio comparing highest intubation quartile vs. lowest intubation quartile, 0.81; 95% confidence interval (CI), 0.74 to 0.90; p value < .001). This association was modified by the presence of respiratory failure prior to arrest (p for interaction < .001), and stratified analyses demonstrated lower patient survival at hospitals with higher rates of endotracheal intubation was limited to patients without respiratory failure prior to cardiac arrest.

CONCLUSION

In a national sample of patients suffering IHCA, the use of endotracheal intubation during CPR varied across hospitals. We found a strong inverse association between hospital use of endotracheal intubation during CPR and survival to discharge, but this association was confined to patients without respiratory failure prior to arrest. Identifying the optimal approach to airway management for in-hospital cardiac arrest may have a significant impact on patient survival.

Manikin study showed that counting inflation breaths out loud improved the speed of resuming chest compressions during two-person paediatric cardiopulmonary resuscitation

AIM

We investigated whether counting inflation breaths out loud during cardiopulmonary resuscitation (CPR) led to an earlier resumption of chest compressions.

METHODS

In this randomised controlled manikin simulation study, conducted from February 2015 to April 2015, 32 fourth-year Korean medical students, equally divided into study and control groups, performed 10 cycles of 15:2 CPR while administering inflation breaths using a bag mask. The first study participant counted the number of inflation breaths out loud, and the second study participant was told to perform chest compressions as soon as they heard their colleague say two. The control group did not count out loud. The groups were blinded to the study outcomes and put in separate rooms.

RESULTS

The median chest compression interruption time was shorter in the study group than the control group (40 vs 46 seconds, p < 0.01, r = 0.70), and the median chest compression fraction (CCF) was higher (68 vs 62%, p < 0.01, r = 0.71). Other quality outcomes related chest compressions and ventilation did not differ between the groups.

CONCLUSION

Counting the number of inflation breaths out loud was a simple method that improved the speed of resuming chest compressions and increased CCFs in 15:2 CPR.

Safety and applicability of a pre-stage public access ventilator for trained laypersons: a proof of principle study

BACKGROUND

Contemporary resuscitation guidelines for basic life support recommend an immediate onset of cardiac compressions in case of cardiac arrest followed by rescue breaths. Effective ventilation is often omitted due to fear of doing harm and fear of infectious diseases. In order to improve ventilation a pre-stage of an automatic respirator was developed for use by laypersons.

METHODS

Fifty-two healthy volunteers were ventilated by means of a prototype respirator via a full-face mask in a pilot study. The pre-stage public access ventilator (PAV) consisted of a low-cost self-designed turbine, with sensors for differential pressure, flow, FO₂, FCO₂ and 3-axis acceleration measurement. Sensor outputs were used to control the respirator and to recognize conditions relevant for efficiency of ventilation and patients' safety. Different respiratory manoeuvres were applied: a) pressure controlled ventilation (PCV), b) PCV with controlled leakage and c) PCV with simulated airway occlusion. Sensor signals were analysed to detect leakage and airway occlusion. Detection based upon sensor signals was compared with evaluation based on clinical observation and additional parameters such as exhaled CO₂.

RESULTS

Pressure controlled ventilation could be realized in all volunteers. Leakage was recognized with 93.5% sensitivity and 93.5% specificity. Simulated airway occlusion was detected with 91.8% sensitivity and 91.7% specificity.

CONCLUSION

The pre-stage PAV was able to detect potential complications relevant for patients' safety such as leakage and airway occlusion in a proof of principle study. Prospectively, this device provides a respectable basis for the development of an automatic emergency respirator and may help to improve bystander resuscitation.

European cardiovascular nurses’ and allied professionals’ knowledge and practical skills regarding cardiopulmonary resuscitation

Purpose:

Cardiopulmonary resuscitation (CPR) remains a cornerstone in the treatment of cardiac arrest, and is directly linked to survival rates. Nurses are often first responders and need to be skilled in the performance of cardiopulmonary resuscitation. As cardiopulmonary resuscitation skills deteriorate rapidly, the purpose of this study was to investigate whether there was an association between participants’ cardiopulmonary resuscitation training and their practical cardiopulmonary resuscitation test results.

Methods:

This comparative study was conducted at the 2014 EuroHeartCare meeting in Stavanger ( n=133) and the 2008 Spring Meeting on Cardiovascular Nursing in Malmö ( n=85). Participants performed cardiopulmonary resuscitation for three consecutive minutes CPR training manikins from Laerdal Medical®. Data were collected with a questionnaire on demographics and participants’ level of cardiopulmonary resuscitation training.

Results:

Most participants were female (78%) nurses (91%) from Nordic countries (77%), whose main role was in nursing practice (63%), and 71% had more than 11 years’ experience ( n=218). Participants who conducted cardiopulmonary resuscitation training once a year or more ( n=154) performed better regarding ventilation volume than those who trained less (859 ml vs. 1111 ml, p=0.002). Those who had cardiopulmonary resuscitation training offered at their workplace ( n=161) also performed better regarding ventilation volume (889 ml vs. 1081 ml, p=0.003) and compression rate per minute (100 vs. 91, p=0.04) than those who had not.

Conclusion:

Our study indicates a positive association between participants’ performance on the practical cardiopulmonary resuscitation test and the frequency of cardiopulmonary resuscitation training and whether cardiopulmonary resuscitation training was offered in the workplace. Large ventilation volumes were the most common error at both measuring points.

Team Size and Stretching-Exercise Effects on Simulated Chest Compression Performance and Exertion

Introduction

Investigators conducted a prospective experimental study to evaluate the effect of team size and recovery exercises on individual providers’ compression quality and exertion. Investigators hypothesized that 1) larger teams would perform higher quality compressions with less exertion per provider when compared to smaller teams; and 2) brief stretching and breathing exercises during rest periods would sustain compressor performance and mitigate fatigue.

Methods

In Phase I, a volunteer cohort of pre-clinical medical students performed four minutes of continuous compressions on a Resusci-Anne manikin to gauge the spectrum of compressor performance in the subject population. Compression rate, depth, and chest recoil were measured. In Phase II, the highest-performing Phase I subjects were placed into 2-, 3-, and/or 4-compressor teams; 2-compressor teams were assigned either to control group (no recovery exercises) or intervention group (recovery exercises during rest). All Phase II teams participated in 20-minute simulations with compressor rotation every two minutes. Investigators recorded compression quality and real-time heart rate data, and calculated caloric expenditure from contact heart rate monitor measurements using validated physiologic formulas.

Results

Phase I subjects delivered compressions that were 24.9% (IQR1–3: [0.5%–74.1%]) correct with a median rate of 112.0 (IQR1–3: [103.5–124.9]) compressions per minute and depth of 47.2 (IQR1–3: [35.7–55.2]) mm. In their first rotations, all Phase II subjects delivered compressions of similar quality and correctness (p=0.09). Bivariate analyses of 2-, 3-, and 4-compressor teams’ subject compression characteristics by subsequent rotation did not identify significant differences within or across teams. On multivariate analyses, only subjects in 2-compressor teams exhibited significantly lower compression rates (control subjects; p<0.01), diminished chest release (intervention subjects; p=0.03), and greater exertion over successive rotations (both control [p≤0.03] and intervention [p≤0.02] subjects).

Conclusion

During simulated resuscitations, 2-compressor teams exhibited increased levels of exertion relative to 3- and 4-compressor teams for comparable compression delivery. Stretching and breathing exercises intended to assist with compressor recovery exhibited mixed effects on compression performance and subject exertion.

Impact of a feedback device on chest compression quality during extended manikin CPR: a randomized crossover study

PURPOSES

Chest compressions require physical effort leading to increased fatigue and rapid degradation in the quality of cardiopulmonary resuscitation overtime. Despite harmful effect of interrupting chest compressions, current guidelines recommend that rescuers switch every 2 minutes. The impact on the quality of chest compressions during extended cardiopulmonary resuscitation has yet to be assessed.

BASIC PROCEDURES

We conducted randomized crossover study on manikin (ResusciAnne; Laerdal). After randomization, 60 professional emergency rescuers performed 2 × 10 minutes of continuous chest compressions with and without a feedback device (CPRmeter). Efficient compression rate (primary outcome) was defined as the frequency target reached along with depth and leaning at the same time (recorded continuously).

MAIN FINDINGS

The 10-minute mean efficient compression rate was significantly better in the feedback group: 42% vs 21% (P< .001). There was no significant difference between the first (43%) and the tenth minute (36%; P= .068) with feedback. Conversely, a significant difference was evident from the second minute without feedback (35% initially vs 27%; P< .001). The efficient compression rate difference with and without feedback was significant every minute, from the second minute onwards. CPRmeter feedback significantly improved chest compression depth from the first minute, leaning from the second minute and rate from the third minute.

PRINCIPAL CONCLUSIONS

A real-time feedback device delivers longer effective, steadier chest compressions over time. An extrapolation of these results from simulation may allow rescuer switches to be carried out beyond the currently recommended 2 minutes when a feedback device is used.

Comparison of chest compression interruption times across 2 automated devices: a randomized, crossover simulation study

OBJECTIVE

The goal of this study was to compare chest compression interruption times required to apply, adjust, and remove 2 different automated chest compression (ACC) devices using the same evaluation protocol.

METHODS

Twenty-nine registered nurses and respiratory therapists used 2 ACC devices in separate resuscitation scenarios involving a patient manikin simulating a 45-year-old man in cardiac arrest in his intensive care unit room. Device presentation was randomized, with half of the participants using LUCAS 2 in the first scenario and the other half using AutoPulse in the first scenario.

RESULTS

The mean chest compression interruption time to apply the ACC device to the patient was significantly shorter for AutoPulse (mean [M] = 31.6 ± 8.44) than for LUCAS 2 (M = 39.1 ± 11.20; t(28) = 3.65, P = .001). The mean chest compression interruption time to remove the ACC device from the patient and resume manual compressions was also significantly shorter for AutoPulse (M = 6.5 ± 3.65) than for LUCAS 2 (M = 10.1 ± 3.97; t(26) = 3.36, P = .002). There was no difference in the mean chest compression interruption time to adjust the position of the ACC device on the patient between AutoPulse (M = 14.3 ± 5.24) and LUCAS 2 (M = 12.5 ± 3.89; t(23) = -1.45, P = .162).

CONCLUSIONS

The results of this study trended in favor of AutoPulse. However, the interruption in chest compression to apply either device to the patient was notably longer than the maximum interruption time recommended by the American Heart Association.

Association Between Chest Compression Interruptions and Clinical Outcomes of Ventricular Fibrillation Out-of-Hospital Cardiac Arrest

BACKGROUND

Minimizing pauses in chest compressions during cardiopulmonary resuscitation is a focus of current guidelines. Prior analyses found that prolonged pauses for defibrillation (perishock pauses) are associated with worse survival. We analyzed resuscitations to characterize the association between pauses for all reasons and both ventricular fibrillation termination and patient survival.

METHODS AND RESULTS

In 319 patients with ventricular tachycardia/fibrillation out-of-hospital cardiac arrest, we analyzed recordings from all defibrillators used during resuscitation and measured durations of all cardiopulmonary resuscitation pauses. Median durations were 32 seconds (25th and 75th percentile, 22 and 52 seconds) for the longest pause for any reason, 23 seconds (25th and 75th percentile, 14 and 34 seconds) for the longest perishock pause, and 24 seconds (25th and 75th percentile, 11 and 38 seconds) for the longest nonshock pause. Multivariable regression models showed lower odds for survival per 5-second increase in the longest overall pause (odds ratio, 0.89; 95% confidence interval, 0.83-0.95), longest perishock pause (odds ratio, 0.85; 95% confidence interval, 0.77-0.93), and longest nonshock pause (odds ratio, 0.83; 95% confidence interval, 0.75-0.91). In 36% of cases, the longest pause was a nonshock pause; this subgroup had lower survival than the group in whom the longest pause was a perishock pause (27% versus 44%, respectively; P<0.01) despite a higher chest compression fraction. Preshock pauses were 8 seconds (25th and 75th percentile, 4 and 17 seconds) for shocks that terminated ventricular fibrillation and 7 seconds (25th and 75th percentile, 4 and 13 seconds) for shocks that did not (P=0.18).

CONCLUSIONS

Prolonged pauses have a negative association with survival not explained by chest compression fraction or decreased ventricular fibrillation termination rate. Ventricular fibrillation termination was not the mechanism linking pause duration and survival. Strategies shortening the longest pauses may improve outcome.

Systematic review of the mechanisms driving effective blood flow during adult CPR

BACKGROUND

High quality chest compressions is the most significant factor related to improved short-term and long-term outcome in cardiac arrest. However, considerable controversy exists over the mechanisms involved in driving blood flow.

OBJECTIVES

The aim of this systematic review is to elucidate major mechanisms involved in effective compression-mediated blood flow during adult cardiopulmonary resuscitation (CPR).

DESIGN AND SETTING

Systematic review of studies identified from the bibliographic databases of PubMed/Medline, Cochrane, and Scopus.

SELECTION CRITERIA

All human and animal studies including information on the responsible mechanisms of compression-related blood flow.

DATA COLLECTION AND ANALYSIS

Two reviewers (MG, TX) independently screened all potentially relevant titles and abstracts for eligibility, by using a standardized data-worksheet.

MAIN RESULTS

Forty seven studies met the inclusion criteria. Because of the heterogeneity in outcome measures, quantitative synthesis of evidence was not feasible. Evidence was critically synthesized in order to answer the review questions, taking into account study heterogeneity and validity. The number of included studies per category is as follows: blood flow during chest compression, nine studies; blood flow during chest decompression, six studies; effect of chest compression on cerebral blood flow, eight studies; active compression-decompression CPR, 14 studies; and effect of ventilation on compression-related blood flow, 13 studies.

CONCLUSION

The evidence so far is inconclusive regarding the major responsible mechanism in compression-related blood flow. Although both 'cardiac pump' and 'thoracic pump' have a key role, the effect of each mechanism is highly depended on other resuscitation parameters, such as positive pressure ventilation and compression depth.