Plasma endothelin-1 level at the onset of ischemic ventricular fibrillation predicts resuscitation outcome

Comparing anesthesia with isoflurane and fentanyl/fluanisone/midazolam in a rat model of cardiac arrest

Only one in ten patients survives cardiac arrest (CA), underscoring the need to improve CA management. Isoflurane has shown cardio- and neuroprotective effects in animal models of ischemia-reperfusion injury. Therefore, the beneficial effect of isoflurane should be tested in an experimental CA model. We hypothesize that isoflurane anesthesia improves short-term outcome following resuscitation from CA compared with a subcutaneous fentanyl/fluanisone/midazolam anesthesia. Male Sprague-Dawley rats were randomized to anesthesia with isoflurane ( n = 11) or fentanyl/fluanisone/midazolam ( n = 11). After 10 min of asphyxial CA, animals were resuscitated by mechanical chest compressions, ventilations, and epinephrine and observed for 30 min. Hemodynamics, including coronary perfusion pressure, systemic O2 consumption, and arterial blood gases, were recorded throughout the study. Plasma samples for endothelin-1 and cathecolamines were drawn before and after CA. Compared with fentanyl/fluanisone/midazolam anesthesia, isoflurane resulted in a shorter time to return of spontaneous circulation (ROSC), less use of epinephrine, increased coronary perfusion pressure during cardiopulmonary resusitation, higher mean arterial pressure post-ROSC, increased plasma levels of endothelin-1, and decreased levels of epinephrine. The choice of anesthesia did not affect ROSC rate or systemic O2 consumption. Isoflurane reduces time to ROSC, increases coronary perfusion pressure, and improves hemodynamic function, all of which are important parameters in CA models.

NEW & NOTEWORTHY The preconditioning effect of volatile anesthetics in studies of ischemia-reperfusion injury has been demonstrated in several studies. This study shows the importance of anesthesia in experimental cardiac arrest studies as isoflurane raised coronary perfusion pressure during resuscitation, reduced time to return of spontaneous circulation, and increased arterial blood pressure in the post-cardiac arrest period. These effects on key outcome measures in cardiac arrest research are important in the interpretation of results from animal studies.

High Serum Tumor Necrosis Factor Levels in the Early Post-Cardiac Arrest Period Are Associated with Poor Short-Term Survival in a Swine Model of Ventricular Fibrillation

Most resuscitated victims of out-of-hospital cardiac arrest who survive to hospital expire due to the postresuscitation syndrome. This syndrome is characterized by a sepsis-like proinflammatory state. The objective of this investigation was to determine whether a relationship exists between the rise of tumor necrosis factor (TNF), a proinflammatory cytokine, following return of spontaneous circulation (ROSC), and early postarrest survival in a clinically relevant animal model of spontaneous ventricular fibrillation (VF). Mixed-breed Yorkshire swine (n = 20), weighing 39 ± 5 kg, were anesthetized and catheters placed in the right atrium and left ventricle/ascending aorta for continuous pressure monitoring. VF was induced by occluding the left anterior descending coronary artery with an angioplasty balloon. After 7 min of untreated VF, advanced life support resuscitation attempts were made for up to 20 min. Animals achieving ROSC were monitored for 3 h and fluid and pressor support was administered as needed. TNF levels were measured before VF and at 0, 15, and 30 min after ROSC using quantitative sandwich enzyme-linked immunosorbent assay. Twelve (60%) animals experienced early death, expiring during the 3 hour postarrest period (9 pulseless electrical activity, 2 VF, and 1 asystole). The TNF level at 15 min post-ROSC was significantly associated with death within the first 3 h post-ROSC with a univariate odds ratio of 1.4 [95% confidence interval (CI) 1.05-2.2, P = 0.01]. Using a cutoff TNF level of 525 pg/mL at 15 min post-ROSC had 100% negative predictive value (95% CI 0%-37%) and 67% positive predictive value (95% CI 35%-90%) for early death with a hazard ratio of 6.6 (95% CI 1.9-23.5). TNF increases shortly after ROSC and is predictive of early death. Early identification of resuscitated victims at greatest risk for hemodynamic collapse and recurrent arrest might facilitate the use of early hospital-based interventions to decrease the likelihood of a poor outcome.

1H NMR-metabolomics: can they be a useful tool in our understanding of cardiac arrest?

OBJECTIVE

This review focuses on the presentation of the emerging technology of metabolomics, a promising tool for the detection of identifying the unrevealed biological pathways that lead to cardiac arrest.

DATA SOURCES

The electronic bases of PubMed, Scopus, and EMBASE were searched. Research terms were identified using the MESH database and were combined thereafter. Initial search terms were "cardiac arrest", "cardiopulmonary resuscitation", "post-cardiac arrest syndrome" combined with "metabolomics".

RESULTS

Metabolomics allow the monitoring of hundreds of metabolites from tissues or body fluids and already influence research in the field of cardiac metabolism. This approach has elucidated several pathophysiological mechanisms and identified profiles of metabolic changes that can be used to follow the disease processes occurring in the peri-arrest period. This can be achieved through leveraging the strengths of unbiased metabolome-wide scans, which include thousands of final downstream products of gene transcription, enzyme activity and metabolic products of extraneously administered substances, in order to identify a metabolomic fingerprint associated with an increased risk of cardiac arrest.

CONCLUSION

Although this technology is still under development, metabolomics is a promising tool for elucidating biological pathways and discovering clinical biomarkers, strengthening the efforts for optimizing both the prevention and treatment of cardiac arrest.

Endothelin-1 attenuates the hemodynamic response to exogenous epinephrine in a porcine ischemic ventricular fibrillation cardiac arrest model

Endothelin-1 (ET-1) increases in the ischemically induced ventricular fibrillation (VF) swine model of cardiac arrest and affects outcome by potentially attenuating the hemodynamic response to epinephrine. Fifty-one swine underwent percutaneous left anterior descending occlusion. Seven minutes postonset of ischemic VF, cardiopulmonary resuscitation (CPR) was initiated. If VF persisted after 3 shocks, 1 mg of epinephrine was given. ET-1 (collected at baseline and every 5 min until VF onset) was assayed with ELISA. Bayesian multivariate logistic regression analysis compared peak ET-1 levels with the binary outcome of a positive coronary perfusion pressure response of >20 mmHg following epinephrine. Sixteen animals (31%) failed to achieve a positive response. Restoration of spontaneous circulation (ROSC) was observed in 1/16 (6.3%) of epinephrine nonresponders and 20/35 (57.1%) of epinephrine responders (P = 0.0006). The median peak ET-1 level was 2.71 pg/mL [interquartile range (IQR) 1.06-4.40] in nonresponders and 1.69 pg/mL (IQR 0.99-2.35) in responders. ET-1 levels were inversely associated with epinephrine response with a median posterior odds ratio (OR) of a coronary perfusion pressure response of 0.72 (95% confidence interval [CI] 0.48-1.06) for each one-unit increase in ET-1 and a probability that the associated OR is <1 of 0.95. Peak ET-1 levels predict a lack of a hemodynamic response to epinephrine during treatment of cardiac arrest during ischemic VF.

Epinephrine in resuscitation: curse or cure?

The use of epinephrine during cardiac arrest has been advocated for decades and forms an integral part of the published guidelines. Its efficacy is supported by animal data, but human trial evidence is lacking. This is partly attributable to disparities in trial methodology. Epinephrine’s pharmacologic and physiologic effects include an increase in coronary perfusion pressure that is key to successful resuscitation. One possible explanation for the lack of epinephrine’s demonstrated efficacy in human trials of out-of-hospital cardiac arrest is the delay in its administration. A potential solution may be intraosseus epinephrine, which can be administered quicker. More importantly, it is the quality of the basic life support, early and uninterrupted chest compressions, early defibrillation and postresuscitation care that will provide the best chance of neurologically intact survival.