Combination pharmacotherapy improves neurological outcome after asphyxial cardiac arrest

Pharmacological Approach for Neuroprotection After Cardiac Arrest-A Narrative Review of Current Therapies and Future Neuroprotective Cocktail

Cardiac arrest (CA) results in global ischemia-reperfusion injury damaging tissues in the whole body. The landscape of therapeutic interventions in resuscitation medicine has evolved from focusing solely on achieving return of circulation to now exploring options to mitigate brain injury and preserve brain function after CA. CA pathology includes mitochondrial damage and endoplasmic reticulum stress response, increased generation of reactive oxygen species, neuroinflammation, and neuronal excitotoxic death. Current non-pharmacologic therapies, such as therapeutic hypothermia and extracorporeal cardiopulmonary resuscitation, have shown benefits in protecting against ischemic brain injury and improving neurological outcomes post-CA, yet their application is difficult to institute ubiquitously. The current preclinical pharmacopeia to address CA and the resulting brain injury utilizes drugs that often target singular pathways and have been difficult to translate from the bench to the clinic. Furthermore, the limited combination therapies that have been attempted have shown mixed effects in conferring neuroprotection and improving survival post-CA. The global scale of CA damage and its resultant brain injury necessitates the future of CA interventions to simultaneously target multiple pathways and alleviate the hemodynamic, mitochondrial, metabolic, oxidative, and inflammatory processes in the brain. This narrative review seeks to highlight the current field of post-CA neuroprotective pharmaceutical therapies, both singular and combination, and discuss the use of an extensive multi-drug cocktail therapy as a novel approach to treat CA-mediated dysregulation of multiple pathways, enhancing survival, and neuroprotection.

Chest Compressions in the Delivery Room

Annually, an estimated 13–26 million newborns need respiratory support and 2–3 million newborns need extensive resuscitation, defined as chest compression and 100% oxygen with or without epinephrine in the delivery room. Despite such care, there is a high incidence of mortality and neurologic morbidity. The poor prognosis associated with receiving chest compression alone or with medications in the delivery room raises questions as to whether improved cardiopulmonary resuscitation methods specifically tailored to the newborn could improve outcomes. This review discusses the current recommendations, mode of action, different compression to ventilation ratios, continuous chest compression with asynchronous ventilations, chest compression and sustained inflation optimal depth, and oxygen concentration during cardiopulmonary resuscitation.

Evidence for vasopressors during cardiopulmonary resuscitation in newborn infants

An estimated 0.1% of term infants and up to 15% of preterm infants (2-3 million worldwide) need extensive resuscitation, defined as chest compression and 100% oxygen with or without epinephrine in the delivery room. Despite these interventions, infants receiving extensive resuscitation in the DR have a high incidence of mortality and neurologic morbidity. Successful resuscitation from neonatal cardiac arrest requires the delivery of high-quality chest compression using the most effective vasopressor with the optimal dose, timing, and route of administration during CPR. Current neonatal resuscitation guidelines recommend administration of epinephrine once CPR has started at a dose of 0.01-0.03 mg/kg preferably given intravenously, with repeated doses every 3-5 min until return of spontaneous circulation. This review examines the current evidence for epinephrine and alternative vasopressors during neonatal cardiopulmonary resuscitation.

Prehospital intravenous epinephrine may boost survival of patients with traumatic cardiac arrest: a retrospective cohort study

BACKGROUND

Prehospital resuscitation for patients with major trauma emphasizes a load-and-go principle. For traumatic cardiac arrest (TCA) patients, the administration of vasopressors remains under debate. This study evaluated the effectiveness of epinephrine in the prehospital setting for patients with TCA.

METHODS

We conducted a retrospective cohort study using a prospectively collected registry for out-of-hospital cardiac arrest in Taipei. Enrollees were ≥18 years of age with TCA. Patients with signs of obvious death like decapitation or rigor mortis were excluded. Patients were grouped according to prehospital administration, or lack thereof, of epinephrine. Outcomes were sustained (≥2 h) recovery of spontaneous circulation (ROSC) and survival to discharge. A subgroup analysis was performed by stratified total prehospital time.

RESULTS

From June 1 2010 to May 31 2013, 514 cases were enrolled. Epinephrine was administered in 43 (8.4%) cases. Among all patients, sustained ROSC and survival to discharge was 101 (19.6%) and 20 (3.9%), respectively. The epinephrine group versus the non-epinephrine group had higher sustained ROSC (41.9% vs. 17.6%, p < 0.01) and survival to discharge (14.0% vs. 3.0%, p < 0.01). The adjusted odds ratios (ORs) of epinephrine effect were 2.24 (95% confidence interval (CI) 1.05-4.81) on sustained ROSC, and 2.94 (95% CI 0.85-10.15) on survival to discharge. Subgroup analysis showed increased ORs of epinephrine effect on sustained ROSC with a longer prehospital time.

CONCLUSION

Among adult patients with TCA in an Asian metropolitan area, administration of epinephrine in the prehospital setting was associated with increased short-term survival, especially for those with a longer prehospital time.

The pathophysiologies of asphyxial vs dysrhythmic cardiac arrest: implications for resuscitation and post-event management

BACKGROUND

Cardiac arrest is not a uniform condition and significant heterogeneity exists within all victims with regard to the cause of cardiac arrest. Primary cardiac (dysrhythmic) and asphyxial causes together are responsible for most cases of cardiac arrest at all age groups. The purpose of this article is to review the pathophysiologic differences between dysrhythmic and asphyxial cardiac arrest in the prearrest period, during the no-flow state, and after successful cardiopulmonary resuscitation.

METHODS

The electronic databases of PubMed/Medline, Scopus, and Cochrane were searched for relevant literature and studies.

RESULTS/DISCUSSION

Significant differences exist between dysrhythmic and asphyxial cardiac arrest regarding their pathophysiologic pathways and affect consequently the postresuscitation period. Laboratory data indicate that asphyxial cardiac arrest leads to more widespread postresuscitation brain damage compared with dysrhythmic cardiac arrest. Regarding postresuscitation myocardial dysfunction, few studies have addressed a comparison of the 2 conditions with controversial results.

CONCLUSIONS

Asphyxial cardiac arrest differs significantly from dysrhythmic cardiac arrest with regard to pathophysiologic mechanisms, neuropathologic damage, postresuscitation organ dysfunction, and response to therapy. Both conditions should be considered and treated in a different manner.

Intraarrest rhythms and rhythm conversion in asphyxial cardiac arrest

OBJECTIVES

The objective was to analyze the cardiac arrest rhythms presenting during asphyxial cardiac arrest (ACA).

METHODS

Asphyxial cardiac arrest was induced in 30 Landrace large white piglets, aged 12 to 15 weeks and with a mean (±SD) weight of 20 (±2) kg. After the onset of cardiac arrest, the animals were left untreated for 4 minutes, after which cardiopulmonary resuscitation was commenced. Heart rhythms were monitored from the onset of asphyxia until return of spontaneous circulation or death.

RESULTS

After endotracheal tube clamping and prior to cardiac arrest, normal sinus rhythm was noted in 14 animals, atrial fibrillation in two animals, Mobitz II atrioventricular block in 10 animals, and third-degree atrioventricular block in four animals. At the onset of cardiac arrest, seven animals had ventricular fibrillation (VF), two had asystole, and 21 had pulseless electrical activity (PEA). During the 4-minute period of untreated arrest, however, significant changes in the monitored rhythm were noted; at the end of the fourth minute, 19 animals had VF, two animals had asystole, and nine animals had PEA.

CONCLUSIONS

The most common rhythm after 4 minutes of untreated ACA was VF, while in 57% of animals, PEA was spontaneously converted to VF during the cardiac arrest interval.

Levosimendan Improves Neurological Outcome in a Swine Model of Asphyxial Cardiac Arrest

BACKGROUND

In asphyxial cardiac arrest, the severe hypoxic stress complicates the resuscitation efforts and results in poor neurological outcomes. Our aim was to assess the effects of levosimendan on a swine model of asphyxial cardiac arrest.

METHODS

Asphyxial cardiac arrest was induced in 20 Landrace/Large White piglets, which were subsequently left untreated for four minutes. The animals were randomised to receive adrenaline alone (n=10, Group A) and adrenaline plus levosimendan (n=10, Group B). All animals were resuscitated according to the 2010 European Resuscitation Council guidelines. Haemodynamic variables were measured before arrest, during arrest and resuscitation, and during the first 30 minutes after return of spontaneous circulation (ROSC), while survival and neurologic alertness score were measured 24 hours later.

RESULTS

Return of spontaneous circulation was achieved in six animals (60%) from Group A and nine animals (90%) from Group B (p=0.303). During the first minute of cardiopulmonary resuscitation, coronary perfusion pressure was significantly higher in Group B (p=0.046), but there was no significant difference at subsequent time points until ROSC. Although six animals (60%) from each group survived after 24 hours (p=1.000), neurologic examination was significantly better in the animals of Group B (p<0.01).

CONCLUSIONS

The addition of levosimendan to adrenaline improved coronary perfusion pressure immediately after the onset of cardiopulmonary resuscitation and resulted in better 24-hour neurological outcome.

Adrenaline, terlipressin, and corticoids versus adrenaline in the treatment of experimental pediatric asphyxial cardiac arrest

OBJECTIVE

To analyze if treatment with adrenaline (epinephrine) plus terlipressin plus corticoids achieves higher return of spontaneous circulation than adrenaline in an experimental infant animal model of asphyxial cardiac arrest.

DESIGN

Prospective randomized animal study.

SETTING

Experimental department in a University Hospital.

SUBJECTS

Forty-nine piglets were studied.

INTERVENTIONS

Cardiac arrest was induced by at least 10 minutes of removal of mechanical ventilation and was followed by manual external chest compressions and mechanical ventilation. After 3 minutes of resuscitation, piglets that did not achieve return of spontaneous circulation were randomized to two groups: adrenaline 0.02 mg kg every 3 minutes (20 animals) and adrenaline 0.02 mg kg every 3 minutes plus terlipressin 20 μg kg every 6 minutes plus hydrocortisone 30 mg kg one dose (22 animals). Resuscitation was discontinued when return of spontaneous circulation was achieved or after 24 minutes.

MEASUREMENT AND MAIN RESULTS

Return of spontaneous circulation was achieved in 14 piglets (28.5%), 14.2% with only cardiac massage and ventilation. Return of spontaneous circulation was achieved in 25% of piglets treated with adrenaline and in 9.1% of those treated with adrenaline plus terlipressin plus hydrocortisone (p = 0.167). Return of spontaneous circulation was achieved in 45.4% of animals with pulseless electric activity, 20% with asystole, and 0% with ventricular fibrillation (p = 0.037). Shorter duration of cardiac arrest, higher mean blood pressure and EtCO2 and lower PaCO2 before resuscitation, and higher mean blood pressure during resuscitation were associated with higher return of spontaneous circulation.

CONCLUSIONS

Treatment with adrenaline plus terlipressin plus corticoids does not achieve higher return of spontaneous circulation than that with adrenaline in an infant animal model of asphyxial cardiac arrest.

Adrenaline increases blood-brain-barrier permeability after haemorrhagic cardiac arrest in immature pigs

BACKGROUND

Adrenaline (ADR) and vasopressin (VAS) are used as vasopressors during cardiopulmonary resuscitation. Data regarding their effects on blood-brain barrier (BBB) integrity and neuronal damage are lacking. We hypothesised that VAS given during cardiopulmonary resuscitation (CPR) after haemorrhagic circulatory arrest will preserve BBB integrity better than ADR.

METHODS

Twenty-one anaesthetised sexually immature male piglets (with a weight of 24.3 ± 1.3 kg) were bled 35% via femoral artery to a mean arterial blood pressure of 25 mmHg in the period of 15 min. Afterwards, the piglets were subjected to 8 min of untreated ventricular fibrillation followed by 15 min of open-chest CPR. At 9 min of circulatory arrest, piglets received amiodarone 1.0 mg/kg and hypertonic-hyperoncotic solution 4 ml/kg infusions for 20 min. At the same time, VAS 0.4 U/kg was given intravenously to the VAS group (n = 9) while the ADR group received ADR 20 μg/kg (n = 12). Internal defibrillation was attempted from 11 min of cardiac arrest to achieve restoration of spontaneous circulation. The experiment was terminated 3 h after resuscitation.

RESULTS

The intracranial pressure (ICP) in the post-resuscitation phase was significantly greater in ADR group than in VAS group. VAS group piglets exhibited a significantly smaller BBB disruption compared with ADR group. Cerebral pressure reactivity index showed that cerebral blood flow autoregulation was also better preserved in VAS group.

CONCLUSIONS

Resuscitation with ADR as compared with VAS after haemorrhagic circulatory arrest increased the ICP and impaired cerebrovascular autoregulation more profoundly, as well as exerted an increased BBB disruption though no significant difference in neuronal injury was observed.

Erythropoietin administration facilitates return of spontaneous circulation and improves survival in a pig model of cardiac arrest

BACKGROUND

In addition to its role in the endogenous control of erythropoiesis, recombinant human erythropoietin (rh-EPO) has been shown to exert tissue protective properties in various experimental models. However, its role in the cardiac arrest (CA) setting has not yet been adequately investigated.

AIM

The aim of this study is to examine the effect of rh-EPO in a pig model of ventricular fibrillation (VF)-induced CA.

METHODS

Ventricular fibrillation was electrically induced in 20 piglets and maintained untreated for 8 minutes before attempting resuscitation. Animals were randomized to receive rh-EPO (5000 IU/kg, erythropoietin [EPO] group, n = 10) immediately before the initiation of chest compressions or to receive 0.9% Sodium chloride solution instead (control group, n = 10).

RESULTS

Compared with the control, the EPO group had higher rates of return of spontaneous circulation (ROSC) (100% vs 60%, P = .011) and higher 48-hour survival (100% vs 40%, P = .001). Diastolic aortic pressure and coronary perfusion pressure during cardiopulmonary resuscitation were significantly higher in the EPO group compared with the control group. Erythropoietin-treated animals required fewer number of shocks in comparison with animals that received normal saline (P = .04). Furthermore, the neurologic alertness score was higher in the EPO group compared with that of the control group at 24 (P = .004) and 48 hours (P = .021).

CONCLUSION

Administration of rh-EPO in a pig model of VF-induced CA just before reperfusion facilitates ROSC and improves survival rates as well as hemodynamic variables.

Efficacy of vasopressin during cardio-pulmonary resuscitation in adult patients: a meta-analysis

BACKGROUND

Experimental and animal studies suggested that vasopressin may have a favorable survival profile during CPR. This meta-analysis aimed to determine the efficacy of vasopressin in adult cardiac patients.

METHODOLOGY

Meta-analysis of randomized control trials (RCTs) comparing the efficacy of vasopressin containing regimen during CPR in adult cardiac arrest population with an epinephrine only regimen.

RESULTS

A total of 6120 patients from 10 RCTs were included in this meta-analysis. Vasopressin use during CPR has no beneficial impact in an unselected population in ROSC [OR 1.19, 95% CI 0.93, 1.52], survival to hospital discharge [OR 1.13, 95% CI 0.89, 1.43], survival to hospital admission [OR 1.12, 95% CI 0.99, 1.27] and favorable neurological outcome [OR 1.02, 95% CI 0.75, 1.38]. ROSC in "in-hospital" cardiac arrest setting [OR 2.20, 95% CI 1.08, 4.47] is higher patients receiving vasopressin. Subgroup analyses revealed equal or higher chance of ROSC [OR 2.15, 95% CI 1.00, 4.61], higher possibility of survival to hospital discharge [OR 2.39, 95% CI 1.34, 4.27] and favorable neurological outcome [OR 2.58, 95% CI 1.39, 4.79] when vasopressin was used as repeated boluses of 4-5 times titrating desired effects during CPR.

CONCLUSION

ROSC in "in-hospital" cardiac arrest patients is significantly better when vasopressin was used. A subgroup analysis of this meta-analysis found that ROSC, survival to hospital admission and discharge and favorable neurological outcome may be better when vasopressin was used as repeated boluses of 4-5 times titrated to desired effects; however, overall no beneficial effect was noted in unselected cardiac arrest population.

Research in human resuscitation: what we learn from animals

AIM

It was not until the 18th century that scientists throughout Europe established humane societies to develop resuscitation techniques and to keep registries of successful and unsuccessful cases. Since then, the science and art of cardiopulmonary resuscitation have flourished, multiple international organizations were found, and guidelines are proposed every 5 years in an everlasting attempt to improve the outcome of cardiac arrest victims. The aim of this article is to present the role of animal models in resuscitation research.

METHODS

A comprehensive search in PubMed, CINAHL, Cochrane Library, and Scopus databases was performed.

RESULTS

Mice, rats, and swine have been established as experimental models for conducting resuscitation research. The choice of the animal model is not a simple task, as there are multiple parameters that have to be considered when designing an experiment.

CONCLUSION

Animal models are used extensively in resuscitation research and possess a central role in the effort towards a better understanding of the underlying mechanisms. However, experimental results should always be cautiously extrapolated in humans.