Duty cycle of 33% increases cardiac output during cardiopulmonary resuscitation

Manual versus automatic chest compression devices for cardiopulmonary resuscitation under zero gravity (The MACCC - 0G STUDY)

INTRODUCTION

Cardiopulmonary resuscitation (CPR) in microgravity requires specific methods to counteract weightlessness. Automatic chest compression devices (ACCDs) could improve CPR in microgravity. We aimed to compare ACCDs versus manual CPR in microgravity simulated through parabolic flights.

METHODS

This prospective, open, controlled study compared 3 ACCDs (LUCAS 3©, AUTOPULSE©, EASYPULSE©) to manual CPR during the 66th CNES (Centre National d'Etudes Spatiales) parabolic flights campaign onboard the Novespace Air Zero-G A310 aircraft. Chest compression depths and rates were monitored by a Laerdal© Resusci-Ann-QCPR manikin.

RESULTS

The LUCAS 3© device had a median compression depth of 53.0 [53.0-54.0] mm, significantly higher than the EASYPULSE©, AUTOPULSE©, and Manual CPR (Handstand method), measured at 29.0 [26.0-32.0] mm, 29.0 [27.5-30.7] mm and 34.5 [29.6-43.3] mm, respectively (p value < 0.001). Compression rates were 101 [101-101], 100 [100-100] and 80 [80-80] compressions per minute (cpm) for the LUCAS 3©, EASYPULSE©, and AUTOPULSE©, respectively. Manual CPR provided a significantly higher compression rate with 115 [109-123] cpm (p value < 0.001).

CONCLUSION

Only LUCAS 3© provided effective CPR according to international guidelines. ACCDs should implement microgravity CPR algorithms.

Metrics of impulsiveness of manual chest compressions for out-of-hospital cardiopulmonary resuscitation

Aim

Propose new metrics of impulsiveness of manual chest compressions (CCs) that account for shape and duration, separate the characteristics of the compressive part of the CC cycle from those of the recoil part, and are uncorrelated to CC depth and rate.

Methods

We conducted a retrospective analysis of adult out-of-hospital cardiac arrest monitor-defibrillator recordings having CPR data. Specifically, episodes of adult patients with ≥ 1000 compressions free of leaning were examined. CCs were obtained from the depth signal of the valid episodes, and we calculated the novel metrics: compression area index (CAI), recoil area index (RAI), compression impulsiveness index (CII) and recoil impulsiveness index (RII). Generalized linear mixed-effects models and Jonckheere-Terpstra trend analyses were employed to measure differences between populations and trends, and the absolute value of Pearson's correlation coefficient | r | was used to report dependence between variables. Statistics are reported as median and interquartile range.

Results

We analyzed 982,340 CCs corresponding to 453 episodes, for which we calculated their CAI, RAI and duty cycle (DC). We analyzed the metrics for various populations: age, sex, any ROSC achieved and disposition, and found that CAI was significantly different according to patient disposition and RAI relative to age and sex (p < 0.05 ). None of the metrics was correlated strongly to depth or rate (| r | values of 0.22 or smaller), and all of them varied for CC series corresponding to the same rescuer over the course of resuscitation (p trend < 0.05 ). However, we observed that the metrics are not balanced, in that for any value of DC, CAI and RAI span almost their entire ranges.

Conclusion

The proposed metrics correctly and completely describe manual CC waveforms, improve upon the DC, since they depend on the signal waveform, and provide additional information to current indicators of quality CPR, depth and rate. Furthermore, they allow to differentiate the compressive and recoil parts of the CC cycle, reflecting influence of the rescuer (via CAI or CII) and of the biomechanics of the patient's chest (via RAI or RII). Thus, they have the potential to contribute to better understanding CPR dynamics and, eventually, to enhanced quality of CPR practice as additional indicators of proper manual CC technique.

The association of arterial blood pressure waveform-derived area duty cycle with intra-arrest hemodynamics and cardiac arrest outcomes

AIM

Develop a novel, physiology-based measurement of duty cycle (Arterial Blood Pressure-Area Duty Cycle [ABP-ADC]) and evaluate the association of ABP-ADC with intra-arrest hemodynamics and patient outcomes.

METHODS

This was a secondary retrospective study of prospectively collected data from the ICU-RESUS trial (NCT02837497). Invasive arterial waveform data were used to derive ABP-ADC. The primary exposure was ABP-ADC group (<30%; 30-35%; >35%). The primary outcome was systolic blood pressure (sBP). Secondary outcomes included intra-arrest physiologic goals, CPR quality targets, and patient outcomes. In an exploratory analysis, adjusted splines and receiver operating characteristic (ROC) curves were used to determine an optimal ABP-ADC associated with improved hemodynamics and outcomes using a multivariable model.

RESULTS

Of 1129 CPR events, 273 had evaluable arterial waveform data. Mean age is 2.9 years + 4.9 months. Mean ABP-ADC was 32.5% + 5.0%. In univariable analysis, higher ABP-ADC was associated with lower sBP (p < 0.01) and failing to achieve sBP targets (p < 0.01). Other intra-arrest physiologic parameters, quality metrics, and patient outcomes were similar across ABP-ADC groups. Using spline/ROC analysis and clinical judgement, the optimal ABP-ADC cut point was set at 33%. On multivariable analysis, sBP was significantly higher (point estimate 13.18 mmHg, CI95 5.30-21.07, p < 0.01) among patients with ABP-ADC < 33%. Other intra-arrest physiologic and patient outcomes were similar.

CONCLUSIONS

In this multicenter cohort, a lower ABP-ADC was associated with higher sBPs during CPR. Although ABP-ADC was not associated with outcomes, further studies are needed to define the interactions between CPR mechanics and intra arrest patient physiology.