Influence of Chest Compressions on Circulation during the Peri-Cardiac Arrest Period in Porcine Models

A hands-free carotid Doppler can identify spontaneous circulation without interrupting cardiopulmonary resuscitation: an animal study

BACKGROUND

Identifying spontaneous circulation during cardiopulmonary resuscitation (CPR) is challenging. Current methods, which involve intermittent and time-consuming pulse checks, necessitate pauses in chest compressions. This issue is problematic in both in-hospital cardiac arrest and out-of-hospital cardiac arrest situations, where resources for identifying circulation during CPR may be limited. The fraction of chest compression plays a pivotal role in improving survival rates. To address this challenge, we evaluated a newly developed hands-free, continuous carotid Doppler system (RescueDoppler), designed to identify spontaneous circulation during chest compressions. In our study, we utilized a porcine model of cardiac arrest to investigate sequences of ventricular fibrillation, followed by defibrillation, and monitoring for the return of spontaneous circulation during chest compressions with the carotid Doppler system. We explored both manual compressions at 100 and 50 compressions per minute and mechanical compressions. To estimate the detection rate (i.e., sensitivity), we employed a logistic mixed model with animal identity as random effect.

RESULTS

Offline analysis of Doppler color M-mode and spectral display successfully identified spontaneous circulation during chest compressions in all compression models. Spontaneous circulation was detected in 51 of 59 sequences, yielding an expected sensitivity of 98% with a 95% confidence interval of 59% to 99%.

CONCLUSION

The RescueDoppler, a continuous hands-free carotid Doppler system, demonstrates an expected sensitivity of 98% for identifying spontaneous circulation during both manual and mechanical chest compressions. Clinical studies are needed to further validate these findings.

2024 RECOVER Guidelines: Basic Life Support. Evidence and knowledge gap analysis with treatment recommendations for small animal CPR

OBJECTIVE

To systematically review evidence and devise treatment recommendations for basic life support (BLS) in dogs and cats and to identify critical knowledge gaps.

DESIGN

Standardized, systematic evaluation of literature pertinent to BLS following Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Prioritized questions were each reviewed by 2 Evidence Evaluators, and findings were reconciled by BLS Domain Chairs and Reassessment Campaign on Veterinary Resuscitation (RECOVER) Co-Chairs to arrive at treatment recommendations commensurate to quality of evidence, risk to benefit relationship, and clinical feasibility. This process was implemented using an Evidence Profile Worksheet for each question that included an introduction, consensus on science, treatment recommendations, justification for these recommendations, and important knowledge gaps. A draft of these worksheets was distributed to veterinary professionals for comment for 4 weeks prior to finalization.

SETTING

Transdisciplinary, international collaboration in university, specialty, and emergency practice.

RESULTS

Twenty questions regarding animal position, chest compression point and technique, ventilation strategies, as well as the duration of CPR cycles and chest compression pauses were examined, and 32 treatment recommendations were formulated. Out of these, 25 addressed chest compressions and 7 informed ventilation during CPR. The recommendations were founded predominantly on very low quality of evidence and expert opinion. These new treatment recommendations continue to emphasize the critical importance of high-quality, uninterrupted chest compressions, with a modification suggested for the chest compression technique in wide-chested dogs. When intubation is not possible, bag-mask ventilation using a tight-fitting facemask with oxygen supplementation is recommended rather than mouth-to-nose ventilation.

CONCLUSIONS

These updated RECOVER BLS treatment recommendations emphasize continuous chest compressions, conformation-specific chest compression techniques, and ventilation for all animals. Very low quality of evidence due to absence of clinical data in dogs and cats consistently compromised the certainty of recommendations, emphasizing the need for more veterinary research in this area.

Volumetric Capnography Monitoring and Effects of Epinephrine on Volume of Carbon Dioxide Elimination during Resuscitation after Cardiac Arrest in a Swine Pediatric Ventricular Fibrillatory Arrest

The aim of this study was to examine the use of volumetric capnography monitoring to assess cardiopulmonary resuscitation (CPR) effectiveness by correlating it with cardiac output (CO), and to evaluate the effect of epinephrine boluses on both end-tidal carbon dioxide (EtCO 2 ) and the volume of CO 2 elimination (VCO 2 ) in a swine ventricular fibrillation cardiac arrest model. Planned secondary analysis of data collected to investigate the use of noninvasive monitors in a pediatric swine ventricular fibrillation cardiac arrest model was performed. Twenty-eight ventricular fibrillatory arrests with open cardiac massage were conducted. During CPR, EtCO 2 and VCO 2 had strong correlation with CO, measured as a percentage of baseline pulmonary blood flow, with correlation coefficients of 0.83 ( p  < 0.001) and 0.53 ( p  = 0.018), respectively. However, both EtCO 2 and VCO 2 had weak and nonsignificant correlation with diastolic blood pressure during CPR 0.30 ( p  = 0.484) (95% confidence interval [CI], -0.51-0.83) and 0.25 ( p  = 0.566) (95% CI, -0.55-0.81), respectively. EtCO 2 and VCO 2 increased significantly after the first epinephrine bolus without significant change in CO. The correlations between EtCO 2 and VCO 2 and CO were weak 0.20 ( p  = 0.646) (95% CI, -0.59-0.79), and 0.27 ( p  = 0.543) (95% CI, -0.54-0.82) following epinephrine boluses. Continuous EtCO 2 and VCO 2 monitoring are potentially useful metrics to ensure effective CPR. However, transient epinephrine administration by boluses might confound the use of EtCO 2 and VCO 2 to guide chest compression.

Identification of return of spontaneous circulation during cardiopulmonary resuscitation via pulse oximetry in a porcine animal cardiac arrest model

In this prospective study we investigated whether the pulse oximetry plethysmographic waveform (POP) could be used to identify return of spontaneous circulation (ROSC) during cardio-pulmonary resuscitation (CPR). Tweleve pigs (28 ± 2 kg) were randomly assigned to two groups: Group I (non-arrested with compressions) (n = 6); Group II (arrested with CPR and defibrillation) (n = 6). Hemodynamic parameters and POP were collected and analyzed. POP was analyzed using both a time domain method and a frequency domain method. In Group I, when compressions were carried out on subjects with a spontaneous circulation, a hybrid fluctuation or "envelope" phenomenon appeared in the time domain method and a "double" or "fusion" peak appeared in the frequency domain method. In Group II, after the period of ventricular fibrillation was induced, the POP waveform disappeared. With compressions, POP showed a regular compression wave. After defibrillation, ROSC, and continued compressions, a hybrid fluctuation or "envelope" phenomenon appeared in the time domain method and a "double" or "fusion" peak appeared in the frequency domain method, similar to Group I. Analysis of POP using the time and frequency domain methods could be used to identify ROSC during CPR.