Vasopressors for cardiopulmonary resuscitation. Does pharmacological evidence support clinical practice?

Towards long-acting adrenaline for cardiopulmonary resuscitation: Production and characterization of a liposomal formulation

The use of adrenaline in cardiopulmonary resuscitation is a long-standing medical procedure, recommended by several international guidelines. However, its unspecific action on adrenergic receptors and the need for repeated administrations pose serious concerns about its safety, the balance between benefits and risks being still under debate. To address this issue, a sustained release nano-formulation of adrenaline was developed. Adrenaline was encapsulated into PEGylated, anionic liposomes by a pH-driven loading technique. Particular attention was devoted to the prevention of oxidation of adrenaline by optimizing the preparative process and including an optimal amount of antioxidants in the formulation. The vesicles obtained were then characterized for size, zeta-potential, and lamellarity, while their morphology was described by cryo-TEM. The controlled release properties were confirmed by two different in vitro release-testing methods, and the biocompatibility was assayed on human endothelial cells in vitro.

Can epinephrine therapy be detrimental to patients with hypertrophic cardiomyopathy with hypotension or cardiac arrest? A systematic review

Approximately 10% of sudden cardiac deaths among patients under 35 years of age is owing to hypertrophic cardiomyopathy (HCM)-related cardiac arrest (CA). CA is often associated with pre-arrest or peri-arrest hypotension and is treated by a set of interventions, including the administration of epinephrine. It is debated whether epinephrine increases or decreases survival to discharge following CA. HCM is associated with septal hypertrophy with a dynamic left ventricular outflow tract obstruction and impaired peripheral vasoconstriction in response to α1-adrenergic stimulation, both of which could cause epinephrine to have a different effect than in the general population. This systematic review of the literature aimed to investigate if patients with HCM in CA have a detrimental hemodynamic response to epinephrine. A literature search was performed in October 2016 using Medline (OVID), Embase (Elsevier), and Cochrane Library (Wiley). The initial search generated 2429 articles, of which 22 articles were found to meet inclusion criteria: four physiology studies, 13 case reports of hypotensive HCM patients, and five case reports of HCM patients in CA. The reviewed studies demonstrate that epinephrine effect varies in patients with HCM: in some cases, the expected hypertensive effect was obtained, but in others, a paradoxical hypotensive effect, or no effect, was observed. The probable mechanism of this effect is an increased left ventricular outflow tract obstruction. Other drugs were considered in several of these cases. In summary, the retrieved studies jointly suggest that patients with HCM may respond differently to epinephrine than patients without HCM. The suitability of epinephrine in HCM-associated CA is questionable.

Glucocorticoids as an emerging pharmacologic agent for cardiopulmonary resuscitation

Although cardiac arrest (CA) constitutes a major health problem with dismal prognosis, no specific drug therapy has been shown to improve survival to hospital discharge. CA causes adrenal insufficiency which is associated with poor outcome and increased mortality. Adrenal insufficiency may manifest as an inability to increase cortisol secretion during and after cardiopulmonary resuscitation (CPR). Several studies suggest that glucocorticoids during and after CPR seem to confer benefits with respect to return of spontaneous circulation (ROSC) rates and long term survival. They have beneficial hemodynamic effects that may favor their use during CPR and in the early post-resuscitation period. Moreover, they have anti-inflammatory and anti-apoptotic properties that improve organ function by reducing ischemia/reperfusion (I/R) injury. However, glucocorticoid supplementation has shown conflicting results with regard to survival to hospital discharge and neurological outcome. The purpose of this article is to review the pathophysiology of hypothalamic-pituitary-adrenal (HPA) axis during CPR. Furthermore, this article reviews the effects of glucocorticoids use during CRP and the post-resuscitation phase.

SERCA2a gene therapy in heart failure: an anti-arrhythmic positive inotrope

Therapeutic options that directly enhance cardiomyocyte contractility in chronic heart failure (HF) therapy are currently limited and do not improve prognosis. In fact, most positive inotropic agents, such as β-adrenoreceptor agonists and PDE inhibitors, which have been assessed in HF patients, cause increased mortality as a result of arrhythmia and sudden cardiac death. Cardiac sarcoplasmic reticulum Ca(2)(+) -ATPase2a (SERCA2a) is a key protein involved in sequestration of Ca(2)(+) into the sarcoplasmic reticulum (SR) during diastole. There is a reduction of SERCA2a protein level and function in HF, which has been successfully targeted via viral transfection of the SERCA2a gene into cardiac tissue in vivo. This has enhanced cardiac contractility and reduced mortality in several preclinical models of HF. Theoretical concerns have been raised regarding the possibility of arrhythmogenic adverse effects of SERCA2a gene therapy due to enhanced SR Ca(2)(+) load and induction of SR Ca(2)(+) leak as a result. Contrary to these concerns, SERCA2a gene therapy in a wide variety of preclinical models, including acute ischaemia/reperfusion, chronic pressure overload and chronic myocardial infarction, has resulted in a reduction in ventricular arrhythmias. The potential mechanisms for this unexpected beneficial effect, as well as mechanisms of enhancement of cardiac contractile function, are reviewed in this article.

Epinephrine in out-of-hospital cardiac arrest: A critical review

BACKGROUND

Epinephrine is recommended in advanced cardiac life support guidelines for use in adult cardiac arrest, and has been used in cardiopulmonary resuscitation since 1896. Yet, despite its long time use and incorporation into guidelines, epinephrine suffers from a paucity of evidence regarding its influence on survival. This critical review was conducted to address the knowledge deficit regarding epinephrine in out-of-hospital cardiac arrest and its effect on return of spontaneous circulation, survival to hospital discharge, and neurological performance.

METHODS

The EMBASE and MEDLINE (through the Pubmed interface) databases, and the Cochrane library were searched with the key words "epinephrine", "cardiac arrest" and variations of these terms. Original research studies concerning epinephrine use in adult, out-of-hospital cardiac arrest were selected for further review.

RESULTS

The search yielded nine eligible studies based on inclusion criteria. This includes five prospective cohort studies, one retrospective cohort study, one survival analysis, one case control study, and one RCT. The evidence clearly establishes an association between epinephrine and increased return of spontaneous circulation, the data were conflicting concerning survival to hospital discharge and neurological outcome.

CONCLUSIONS

The results of this review exhibit the paucity of evidence regarding the use of epinephrine in out of hospital cardiac arrest. There is currently insufficient evidence to support or reject its administration during resuscitation. Larger sample, placebo controlled, double blind, randomized control trials need to be performed to definitively establish the effect of epinephrine on both survival to hospital discharge and the neurological outcomes of treated patients.

Early adrenaline administration does not improve circulatory recovery during resuscitation from severe asphyxia in newborn piglets

AIM OF THE STUDY

To investigate the effects of early intravenous adrenaline administration on circulatory recovery, cerebral reoxygenation, and plasma catecholamine concentrations, after severe asphyxia-induced bradycardia and hypotension.

METHODS

One-day-old piglets were left in apnoea until heart rate and mean arterial pressure were less than 50 min(-1) and 25 mmHg, respectively. They randomly received adrenaline, 10 μgkg(-1) (n=16) or placebo (n=15) and were resuscitated with air ventilation and, when needed, closed-chest cardiac massage (CCCM). Eight not asphyxiated animals served as time controls.

RESULTS

CCCM was required in 13 piglets given adrenaline and in 13 given placebo. Time to return of spontaneous circulation was: 72 (66-85)s vs. 77 (64-178)s [median (quartile range)] (p=0.35). Time until cerebral regional oxygen saturation (CrSO(2)) had increased to 30% was 86 (79-152)s vs. 126 (88-309)s (p=0.30). The two groups did not differ significantly in CrSO(2), heart rate, arterial pressure, right common carotid artery blood flow, or number of survivors: 13 vs. 11 animals. Plasma concentration of adrenaline, 2.5 min after resuming ventilation, was 498 (268-868)nmoll(-1) vs. 114 (80-306)nmoll(-1) (p=0.01). Corresponding noradrenaline concentrations were 1799 (1058-4182)nmoll(-1)vs. 1385 (696-3118)nmoll(-1) (ns). In the time controls, the concentrations were 0.4 (0.2-0.6)nmoll(-1) of adrenaline and 1.8 (1.3-2.4)nmoll(-1) of noradrenaline.

CONCLUSION

The high endogenous catecholamine levels, especially those of noradrenaline, may explain why early administered adrenaline did not significantly improve resuscitation outcome.

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.

Cardiac arrest outside and inside hospital in a community: mechanisms behind the differences in outcome and outcome in relation to time of arrest

BACKGROUND

The aim was to compare characteristics and outcome after cardiac arrest where cardiopulmonary resuscitation was attempted outside and inside hospital over 12 years.

METHODS

All out-of-hospital cardiac arrests (OHCAs) in Göteborg between 1994 and 2006 and all in-hospital cardiac arrests (IHCAs) in 1 of the city's 2 hospitals for whom the rescue team was called between 1994 and 2006 were included in the survey.

RESULTS

The study included 2,984 cases of OHCA and 1,478 cases of IHCA. Patients with OHCA differed from those with an IHCA; they were younger, included fewer women, were less frequently found in ventricular fibrillation, and were treated later. If patients were found in a shockable rhythm, survival to 1 month/discharge was 18% after OHCA and 61% after IHCA (P < .0001). Corresponding values for a nonshockable rhythm were 3% and 21% (P < .0001). Survival was higher on daytime and weekdays as compared with nighttime and weekends after IHCA but not after OHCA. Among patients found in a shockable rhythm, a multivariate analysis considering age, gender, witnessed status, delay to defibrillation, time of day, day of week, and location showed that IHCA was associated with increased survival compared with OHCA (adjusted odds ratio 3.18, 95% CI 2.07-4.88).

CONCLUSION

Compared with OHCA, the survival of patients with IHCA increased 3-fold for shockable rhythm and 7-fold for nonshockable rhythm in our practice setting. If patients were found in a shockable rhythm, the higher survival after IHCA was only partly explained by a shorter treatment delay. The time and day of CA were associated with survival in IHCA but not OHCA.

Vasopressin and epinephrine in the treatment of cardiac arrest: an experimental study

BACKGROUND

Epinephrine remains the drug of choice for cardiopulmonary resuscitation. The aim of the present study is to assess whether the combination of vasopressin and epinephrine, given their different mechanisms of action, provides better results than epinephrine alone in cardiopulmonary resuscitation.

METHODS

Ventricular fibrillation was induced in 22 Landrace/Large-White piglets, which were left untreated for 8 minutes before attempted resuscitation with precordial compression, mechanical ventilation and electrical defibrillation. Animals were randomized into 2 groups during cardiopulmonary resuscitation: 11 animals who received saline as placebo (20 ml dilution, bolus) + epinephrine (0.02 mg/kg) (Epi group); and 11 animals who received vasopressin (0.4 IU/kg/20 ml dilution, bolus) + epinephrine (0.02 mg/kg) (Vaso-Epi group). Electrical defibrillation was attempted after 10 minutes of ventricular fibrillation.

RESULTS

Ten of 11 animals in the Vaso-Epi group restored spontaneous circulation in comparison to only 4 of 11 in the Epi group (p = 0.02). Aortic diastolic pressure, as well as, coronary perfusion pressure were significantly increased (p < 0.05) during cardiopulmonary resuscitation in the Vaso-Epi group.

CONCLUSION

The administration of vasopressin in combination with epinephrine during cardiopulmonary resuscitation results in a drastic improvement in the hemodynamic parameters necessary for the return of spontaneous circulation.