Esmolol for cardioprotection during resuscitation with adrenaline in an ischaemic porcine cardiac arrest model

Extracorporeal cardiopulmonary resuscitation: a comparison of two experimental approaches and systematic review of experimental models

BACKGROUND

In patients requiring extracorporeal cardiopulmonary resuscitation (ECPR), there is a need for studies to assess the potential benefits of therapeutic interventions to improve survival and reduce hypoxic-ischemic brain injuries. However, conducting human studies may be challenging. This study aimed to describe two experimental models developed in our laboratory and to conduct a systematic review of existing animal models of ECPR reported in the literature.

RESULTS

In our experiments, pigs were subjected to 12 min (model 1) or 5 min (model 2) of untreated ventricular fibrillation, followed by 18 min (model 1) or 25 min (model 2) of conventional cardiopulmonary resuscitation. Results showed severe distributive shock, decreased brain oxygen pressure and increased intracranial pressure, with model 1 displaying more pronounced brain perfusion impairment. A systematic review of 52 studies, mostly conducted on pigs, revealed heterogeneity in cardiac arrest induction methods, cardiopulmonary resuscitation strategies, and evaluated outcomes.

CONCLUSIONS

This review emphasizes the significant impact of no-flow and low-flow durations on brain injury severity following ECPR. However, the diversity in experimental models hinders direct comparisons, urging the standardization of ECPR models to enhance consistency and comparability across studies.

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

OBJECTIVE

To systematically review the evidence and devise clinical recommendations on advanced life support (ALS) in dogs and cats and to identify critical knowledge gaps.

DESIGN

Standardized, systematic evaluation of literature pertinent to ALS following Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Prioritized questions were each reviewed by Evidence Evaluators, and findings were reconciled by ALS Domain Chairs and Reassessment Campaign on Veterinary Resuscitation (RECOVER) Co-Chairs to arrive at treatment recommendations commensurate to quality of evidence, risk: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

Seventeen questions pertaining to vascular access, vasopressors in shockable and nonshockable rhythms, anticholinergics, defibrillation, antiarrhythmics, and adjunct drug therapy as well as open-chest CPR were reviewed. Of the 33 treatment recommendations formulated, 6 recommendations addressed the management of patients with nonshockable arrest rhythms, 10 addressed shockable rhythms, and 6 provided guidance on open-chest CPR. We recommend against high-dose epinephrine even after prolonged CPR and suggest that atropine, when indicated, is used only once. In animals with a shockable rhythm in which initial defibrillation was unsuccessful, we recommend doubling the defibrillator dose once and suggest vasopressin (or epinephrine if vasopressin is not available), esmolol, lidocaine in dogs, and/or amiodarone in cats.

CONCLUSIONS

These updated RECOVER ALS guidelines clarify the approach to refractory shockable rhythms and prolonged CPR. Very low quality of evidence due to absence of clinical data in dogs and cats continues to compromise the certainty with which recommendations can be made.

Cardiac Arrest in Pigs With 48 hours of Post-Resuscitation Care Induced by 2 Methods of Myocardial Infarction: A Methodological Description

Background

Systematic reviews have disclosed a lack of clinically relevant cardiac arrest animal models. The aim of this study was to develop a cardiac arrest model in pigs encompassing relevant cardiac arrest characteristics and clinically relevant post‐resuscitation care.

Methods and Results

We used 2 methods of myocardial infarction in conjunction with cardiac arrest. One group (n=7) had a continuous coronary occlusion, while another group (n=11) underwent balloon‐deflation during arrest and resuscitation with re‐inflation after return of spontaneous circulation. A sham group was included (n=6). All groups underwent 48 hours of intensive care including 24 hours of targeted temperature management. Pigs underwent invasive hemodynamic monitoring. Left ventricular function was assessed by pressure‐volume measurements. The proportion of pigs with return of spontaneous circulation was 43% in the continuous infarction group and 64% in the deflation‐reinflation group. In the continuous infarction group 29% survived the entire protocol while 55% survived in the deflation‐reinflation group. Both cardiac arrest groups needed vasopressor and inotropic support and pressure‐volume measurements showed cardiac dysfunction. During rewarming, systemic vascular resistance decreased in both cardiac arrest groups. Median [25%;75%] troponin‐I 48 hours after return of spontaneous circulation, was 88 973 ng/L [53 124;99 740] in the continuous infarction group, 19 661 ng/L [10 871;23 209] in the deflation‐reinflation group, and 1973 ng/L [1117;1995] in the sham group.

Conclusions

This article describes a cardiac arrest pig model with myocardial infarction, targeted temperature management, and clinically relevant post‐cardiac arrest care. We demonstrate 2 methods of inducing myocardial ischemia with cardiac arrest resulting in post‐cardiac arrest organ injury including cardiac dysfunction and cerebral injury.

The Efficacy and Safety of Esmolol for Septic Shock: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Purpose: The meta-analysis aims to identify whether septic shock patients can benefit from esmolol.

Materials and Methods: The relevant studies from MEDLINE, Cochrane Library, Embase were searched by two independent investigators using a variety of keywords. Stata software (version 12.0, Stata Corp LP, College Station, TX, United States)was used for statistical analysis.

Results: A total of 14 studies were identified and incorporated into the meta-analysis. For overall analysis, the treatment of esmolol was associated with decreased 28-day mortality (RR = 0.66, 95% CI = 0.56–0.77, p < 0.001). Meanwhile, our analysis found that, esmolol could decrease HR (SMD: −1.70; 95% CI: [−2.24−(−1.17)], cTnI (SMD: −1.61; 95% CI: [−2.06−(−1.16)] compared with standard treatment. No significant differences between the two groups were found in MAP, Lac, CI, and SVI.

Conclusion: The findings of this meta-analysis intend to demonstrate that septic shock patients with high heart beats rate might be benefit from esmolol treatment despite enough fluid resuscitation. While, dependent on the study published, with the further development of septic shock, the positive impact of esmolol varies. The appropriate heart rate change interval cannot be confirmed, further high-quality and large-scale RCTs should be performed to verify it and screening more suitable heart rate levels.

Systematic Review Registration: CRD42021239513

Esmolol during cardiopulmonary resuscitation reduces neurological injury in a porcine model of cardiac arrest

Primary vasopressor efficacy of epinephrine during cardiopulmonary resuscitation (CPR) is due to its α-adrenergic effects. However, epinephrine plays β1-adrenergic actions, which increasing myocardial oxygen consumption may lead to refractory ventricular fibrillation (VF) and poor outcome. Effects of a single dose of esmolol in addition to epinephrine during CPR were investigated in a porcine model of VF with an underlying acute myocardial infarction. VF was ischemically induced in 16 pigs and left untreated for 12 min. During CPR, animals were randomized to receive epinephrine (30 µg/kg) with either esmolol (0.5 mg/kg) or saline (control). Pigs were then observed up to 96 h. Coronary perfusion pressure increased during CPR in the esmolol group compared to control (47 ± 21 vs. 24 ± 10 mmHg at min 5, p < 0.05). In both groups, 7 animals were successfully resuscitated and 4 survived up to 96 h. No significant differences were observed between groups in the total number of defibrillations delivered prior to final resuscitation. Brain histology demonstrated reductions in cortical neuronal degeneration/necrosis (score 0.3 ± 0.5 vs. 1.3 ± 0.5, p < 0.05) and hippocampal microglial activation (6 ± 3 vs. 22 ± 4%, p < 0.01) in the esmolol group compared to control. Lower circulating levels of neuron specific enolase were measured in esmolol animals compared to controls (2[1-3] vs. 21[16-52] ng/mL, p < 0.01). In this preclinical model, β1-blockade during CPR did not facilitate VF termination but provided neuroprotection.

Esmolol in the management of pre-hospital refractory ventricular fibrillation: A systematic review and meta-analysis

BACKGROUND

Esmolol has been proposed as a viable adjunctive therapy for pre-hospital refractory ventricular fibrillation/pulseless ventricular tachycardia (VF/pVT).

OBJECTIVES

We performed a systematic review and meta-analysis to assess the effectiveness of esmolol on pre-hospital refractory VF/pVT, compared with standard of care.

METHODS

MEDLINE, Embase, Scopus, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched for eligible studies. Two investigators independently extracted relevant data and assessed the methodological quality of each included study using the ROBINS-I tool. The quality of evidence for summary estimates was assessed according to GRADE guidelines. Pooled risk ratios (RRs) with 95% confidence intervals (CIs) for each outcome of interest were calculated.

RESULTS

The search yielded 3253 unique records, of which two studies were found to be in accordance with the research purpose, totaling 66 patients, of whom 33.3% (n = 22) received esmolol. Additional evidence was provided in the paper but was not relevant to the analysis and was therefore not included. Esmolol was likely associated with an increased rate of survival to discharge (RR 2.82, 95% CI 1.01-7.93, p = 0.05) (GRADE: Very low) and survival with favorable neurological outcome (RR 3.44, 95% CI 1.11-10.67, p = 0.03) (GRADE: Very low). Similar results were found for return of spontaneous circulation (ROSC) (RR 2.63, 95% CI 1.37-5.07, p = 0.004) (GRADE: Very low) and survival to intensive care unit (ICU)/hospital admission (RR 2.63, 95% CI 1.37-5.07, p = 0.004) (GRADE: Very low).

CONCLUSION

The effectiveness of esmolol for refractory VF/pVT remains unclear. Trial sequential analysis (TSA) indicates that the evidence is inconclusive and that further trials are required in order to reach a conclusion. Therefore, it is imperative to continue to accumulate evidence in order to obtain a higher level of scientific evidence.