Magnesium sulfate in the treatment of refractory ventricular fibrillation in the prehospital setting

The role of magnesium in cardiac arrest

Cardiac arrest is a leading cause of death globally. Only 25.8% of in-hospital and 33.5% of out-of-hospital individuals who achieve spontaneous circulation following cardiac arrest survive to leave the hospital. Respiratory failure and acute coronary syndrome are the two most common etiologies of cardiac arrest. Effort has been made to improve the outcomes of individuals resuscitated from cardiac arrest. Magnesium is an ion that is critical to the function of all cells and organs. It is often overlooked in everyday clinical practice. At present, there have only been a small number of reviews discussing the role of magnesium in cardiac arrest. In this review, for the first time, we provide a comprehensive overview of magnesium research in cardiac arrest focusing on the effects of magnesium on the occurrence and prognosis of cardiac arrest, as well as in the two main diseases causing cardiac arrest, respiratory failure and acute coronary syndrome. The current findings support the view that magnesium disorder is associated with increased risk of cardiac arrest as well as respiratory failure and acute coronary syndrome.

The Pharmacologic Management of Cardiac Arrest

The effectiveness of pharmacologic management of cardiac arrest patients is widely debated; however, several studies published in the past 5 years have begun to clarify some of these issues. This article covers the current state of evidence for the effectiveness of the vasopressor epinephrine and the combination of vasopressin-steroids-epinephrine and antiarrhythmic medications amiodarone and lidocaine and reviews the role of other medications such as calcium, sodium bicarbonate, magnesium, and atropine in cardiac arrest care. We additionally review the role of β-blockers for refractory pulseless ventricular tachycardia/ventricular fibrillation and thrombolytics in undifferentiated cardiac arrest and suspected fatal pulmonary embolism.

2023 American Heart Association Focused Update on Adult Advanced Cardiovascular Life Support: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

Cardiac arrest is common and deadly, affecting up to 700 000 people in the United States annually. Advanced cardiac life support measures are commonly used to improve outcomes. This "2023 American Heart Association Focused Update on Adult Advanced Cardiovascular Life Support" summarizes the most recent published evidence for and recommendations on the use of medications, temperature management, percutaneous coronary angiography, extracorporeal cardiopulmonary resuscitation, and seizure management in this population. We discuss the lack of data in recent cardiac arrest literature that limits our ability to evaluate diversity, equity, and inclusion in this population. Last, we consider how the cardiac arrest population may make up an important pool of organ donors for those awaiting organ transplantation.

Bicarbonate, calcium, and magnesium for in-hospital cardiac arrest - An instrumental variable analysis

INTRODUCTION

Bicarbonate, calcium, and magnesium are commonly used during in-hospital cardiac arrest. Whether these drugs are associated with survival in cardiac arrest patients is uncertain.

METHODS

This was an observational study using data from the Get With The Guidelines registry. Adult patients with an in-hospital cardiac arrest between January 2008 and December 2021 were included. An instrumental variable approach was used based on hospital preferences for bicarbonate, calcium, and magnesium, respectively. The primary outcome was survival to hospital discharge.

RESULTS

A total of 319,230 patients were included. The median age was 66 years, 59% patients were male, and 85% patients presented with a non-shockable rhythm. Bicarbonate was administered in 58% patients, calcium in 33% patients, and magnesium in 10% patients. When considering drug use in the previous cardiac arrest patient at a given hospital as an instrument, the absolute difference in survival to hospital discharge was estimated at -14.2% (95% CI, -19.9 to -8.6) for bicarbonate, -3.0% (95% CI, -8.6 to 2.6) for calcium, and 10.7% (95% CI, -0.8 to 22.2) for magnesium as compared to no drug. When considering the proportion of drug use within the past year at a given hospital as an instrument, the confidence intervals were very wide, making the results difficult to interpret.

CONCLUSIONS

In this analysis, the results for bicarbonate, calcium, and magnesium were inconclusive due to wide confidence intervals and inconsistencies in estimates across instrumental variables. Randomized trials are needed to investigate the effect of these drugs on patient outcomes.

The Pharmacologic Management of Cardiac Arrest

The effectiveness of pharmacologic management of cardiac arrest patients is widely debated; however, several studies published in the past 5 years have begun to clarify some of these issues. This article covers the current state of evidence for the effectiveness of the vasopressor epinephrine and the combination of vasopressin-steroids-epinephrine and antiarrhythmic medications amiodarone and lidocaine and reviews the role of other medications such as calcium, sodium bicarbonate, magnesium, and atropine in cardiac arrest care. We additionally review the role of β-blockers for refractory pulseless ventricular tachycardia/ventricular fibrillation and thrombolytics in undifferentiated cardiac arrest and suspected fatal pulmonary embolism.

The first case series analysis on efficacy of esmolol injection for in-hospital cardiac arrest patients with refractory shockable rhythms in China

Background: This study assessed the effects of esmolol injection in patients with in-hospital cardiac arrest (IHCA) with refractory ventricular fibrillation (VF)/pulseless ventricular tachycardia (pVT).

Methods: From January 2018 to December 2021, 29 patients with IHCA with refractory shockable rhythm were retrospectively reviewed. Esmolol was administered after advanced cardiovascular life support (ACLS)-directed procedures, and outcomes were assessed.

Results: Among the 29 cases, the rates of sustained return of spontaneous circulation (ROSC), 24-h ROSC, and 72-h ROSC were 79%, 62%, and 59%, respectively. Of those patients, 59% ultimately survived to discharge. Four patients with cardiac insufficiency died. The duration from CA to esmolol infusion was significantly shorter for patients in the survival group (SG) than for patients in the dead group (DG) (12 min, IQR: 8.5–19.5 vs. 23.5 min, IQR: 14.4–27 min; p = 0.013). Of those patients, 76% (22 of 29) started esmolol administration after the second dose of amiodarone. No significant difference was observed in the survival rate between this group and groups administered an esmolol bolus simultaneously or before the second dose of amiodarone (43% vs. 64%, p = 0.403). Of those patients, 31% (9 of 29) were administered an esmolol bolus for defibrillation attempts ≤ 5, while the remaining 69% of patients received an esmolol injection after the fifth defibrillation attempt. No significant differences were observed in the rates of ≥ 24-h ROSC (67% vs. 60%, p = 0.73), ≥ 72-h ROSC (67% vs. 55%, p = 0.56), and survival to hospital discharge (67% vs. 55%, p = 0.56) between the groups administered an esmolol bolus for defibrillation attempts ≤ 5 and defibrillation attempts > 5.

Conclusion: IHCA patients with refractory shockable rhythms receiving esmolol bolus exhibited a high chance of sustained ROSC and survival to hospital discharge. Patients with end-stage heart failure tended to have attenuated benefits from beta-blockers. Further large-scale, prospective studies are necessary to determine the effects of esmolol in patients with IHCA with refractory shockable rhythms.

Successful treatment of prolonged refractory ventricular fibrillation in an anesthetized dog

OBJECTIVE

To describe a case of successful return of spontaneous circulation in an anesthetized dog that developed spontaneous ventricular fibrillation during CPR that was refractory to multiple defibrillation attempts by utilizing pharmacological antiarrhythmic therapy.

CASE SUMMARY

Cardiopulmonary arrest occurred during surgical preparation in a 1-year-old German Shepherd Dog under general anesthesia for fluoroscopic implantation of an Amplatz canine duct occluder for treatment of a patent ductus arteriosus. Pulseless electrical activity was initially diagnosed, and resuscitative efforts were immediately initiated, including basic cardiac life support, discontinuation of anesthesia with administration of reversal agents, and low-dose epinephrine administration (0.01 mg/kg, IV). After 10 minutes of CPR, the patient developed ventricular fibrillation and single-dose monophasic defibrillation attempts of escalating energy were performed. Despite these efforts, return of spontaneous circulation was unable to be achieved. However, administration of magnesium sulfate (20 mg/kg, IV) along with an additional single monophasic defibrillation attempt was successful in achieving return of spontaneous circulation.

NEW OR UNIQUE INFORMATION PROVIDED

Under current advanced cardiac life support guidelines, the best resuscitation strategy for refractory ventricular fibrillation, in which the arrhythmia persists despite multiple defibrillation attempts, remains unclear. This is especially true for veterinary patients, where refractory ventricular fibrillation is an uncommon cardiac arrest rhythm. Although guidelines for the use of antiarrhythmic therapy during cardiac arrest are well established in human medicine, evidence-based guidelines to support best practices in companion animals do not exist due to sparse data gathered through experimental studies. Only a few case reports describe successful return of spontaneous circulation following prolonged ventricular fibrillation in clinical veterinary patients. Although the use of magnesium sulfate as an antiarrhythmic agent during refractory ventricular fibrillation has been previously reported in people, this is the first case to our knowledge of refractory ventricular fibrillation in a dog that responded to magnesium sulfate.

Comparing Drugs for Out-of-hospital, Shock-refractory Cardiac Arrest: Systematic Review and Network Meta-analysis of Randomized Controlled Trials

INTRODUCTION

The benefit of medications used in out-of-hospital, shock-refractory cardiac arrest remains controversial. This study aims to compare the treatment outcomes of medications for out-of-hospital, shock-refractory ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT).

METHODS

The inclusion criteria were randomized controlled trials of participants older than eight years old who had atraumatic, out-of-hospital, shock-refractory VF/pVT in which at least one studied group received a medication. We conducted a database search on October 28, 2019, that included PubMed, Scopus, Web of Science, CINAHL Complete, and Cochrane CENTRAL. Citations of relevant meta-analyses were also searched. We performed frequentist network meta-analysis (NMA) to combine the comparisons. The outcomes were analyzed by using odds ratios (OR) and compared to placebo. The primary outcome was survival to hospital discharge. The secondary outcomes included the return of spontaneous circulation (ROSC), survival to hospital admission, and the neurological outcome at discharge. We ranked all outcomes using surface under the cumulative ranking score.

RESULTS

We included 18 studies with 6,582 participants. The NMA of 20 comparisons included 12 medications and placebo. Only norepinephrine showed a significant increase of ROSC (OR = 8.91, 95% confidence interval [CI], 1.88-42.29). Amiodarone significantly improved survival to hospital admission (OR = 1.53, 95% CI, 1.01-2.32). The ROSC and survival-to-hospital admission data were significantly heterogeneous with the I2 of 55.1% and 59.1%, respectively. This NMA satisfied the assumption of transitivity.

CONCLUSION

No medication was associated with improved survival to hospital discharge from out-of-hospital, shock-refractory cardiac arrest. For the secondary outcomes, norepinephrine was associated with improved ROSC and amiodarone was associated with an increased likelihood of survival to hospital admission in the NMA.

2018 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations Summary

The International Liaison Committee on Resuscitation has initiated a continuous review of new, peer-reviewed, published cardiopulmonary resuscitation science. This is the second annual summary of International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations that includes the most recent cardiopulmonary resuscitation science reviewed by the International Liaison Committee on Resuscitation. This summary addresses the role of antiarrhythmic drugs in adults and children and includes the Advanced Life Support Task Force and Pediatric Task Force consensus statements, which summarize the most recent published evidence and an assessment of the quality of the evidence based on Grading of Recommendations, Assessment, Development, and Evaluation criteria. The statements include consensus treatment recommendations approved by members of the relevant task forces. Insights into the deliberations of each task force are provided in the Values and Preferences and Task Force Insights sections. Finally, the task force members have listed the top knowledge gaps for further research.

2018 American Heart Association Focused Update on Advanced Cardiovascular Life Support Use of Antiarrhythmic Drugs During and Immediately After Cardiac Arrest: An Update to the American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

Antiarrhythmic medications are commonly administered during and immediately after a ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest. However, it is unclear whether these medications improve patient outcomes. This 2018 American Heart Association focused update on advanced cardiovascular life support guidelines summarizes the most recent published evidence for and recommendations on the use of antiarrhythmic drugs during and immediately after shock-refractory ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest. This article includes the revised recommendation that providers may consider either amiodarone or lidocaine to treat shock-refractory ventricular fibrillation/pulseless ventricular tachycardia cardiac arrest.

Drugs in Out-of-Hospital Cardiac Arrest

Managing out-of-hospital cardiac arrest involves unique challenges, including delays in the initiation of advanced interventions and a limited number of trained personnel on scene. Recent out-of-hospital randomized controlled trials, systematic reviews, and metaanalyses provide key insights into what interventions are best proven to positively impact patient outcomes from out-of-hospital cardiac arrest. We review the literature on medications used in out-of-hospital cardiac arrest and summarize evidence-based guidelines from the American Heart Association that form the basis for most emergency medical services cardiac arrest protocols across the United States.

Refractory Out of Hospital Cardiac Arrest

Refractory out of hospital cardiac arrest is a common problem that is associated with poor overall survival rates and neurological outcomes. There are various definitions that have been used but the most accepted one is cardiac arrest that requires more than 10 minutes of Cardiopulmonary Resuscitation (CPR) efforts or more than 3 defibrillation attempts. There have been different pharmacologic and non-pharmacologic therapies that were studied in these patients. None of the antiarrhythmic or vasopressor medications have been consistently shown to improve survival or neurological outcomes in this subset of patients. This has led to the introduction of various devices aimed at improving outcomes such as mechanical CPR devices, Extracorporeal Cardiopulmonary Resuscitation (ECPR), targeted temperature management and early invasive approach. There is accumulating evidence that there seems to be an improvement in outcomes when these devices are used in refractory cardiac arrest patients. But none of these devices have been shown to improve outcomes when used in isolation. This underscores the importance of systematic approach to these complex patients and using these therapies in combination. There has been a paradigm shift in the approach to these patients. Instead of repeated and prolonged CPR attempts in the field, it is suggested that these patients need to be moved to cardiac arrest centers with a mechanical CPR device in place, so a percutaneous Extracorporeal Membrane Oxygenator (ECMO) can be placed to “buy” time for other therapies such as therapeutic hypothermia and early coronary angiography followed by intervention as indicated. Careful selection of patients who might potentially benefit from this approach is critical to the success of these programs.

Effectiveness of antiarrhythmic drugs for shockable cardiac arrest: A systematic review

PURPOSE

The purpose of this systematic review is to provide up-to-date evidence on effectiveness of antiarrhythmic drugs for shockable cardiac arrest to help inform the 2018 International Liaison Committee on Resuscitation Consensus on Science with Treatment Recommendations.

METHODS

A search was conducted in electronic databases Medline, Embase, and Cochrane Library from inception to August 15, 2017.

RESULTS

Of the 9371 citations reviewed, a total of 14 RCTs and 17 observational studies met our inclusion criteria for adult population and only 1 observational study for pediatric population. Based on RCT level evidence for adult population, none of the anti-arrhythmic drugs showed any difference in effect compared with placebo, or with other anti-arrhythmic drugs for the critical outcomes of survival to hospital discharge and discharge with good neurological function. For the outcome of return of spontaneous circulation, the results showed a significant increase for lidocaine compared with placebo (RR = 1.16; 95% CI, 1.03-1.29, p = 0.01).

CONCLUSION

The high level evidence supporting the use of antiarrhythmic drugs during CPR for shockable cardiac arrest is limited and showed no benefit for critical outcomes of survival at hospital discharge, survival with favorable neurological function and long-term survival. Future high quality research is needed to confirm these findings and also to evaluate the role of administering antiarrhythmic drugs in children with shockable cardiac arrest, and in adults immediately after ROSC.

Does Intravenous Magnesium Benefit Patients of Cardiac Arrest? a Meta-Analysis

Objective

Evidence shows that magnesium has anti-arrhythmic roles. However, clinical trials suggest that there are conflicting outcomes of cardiac arrest patients given magnesium. The study aimed to examine the effects of magnesium sulfate therapy on cardiac arrest patients using a meta-analysis.

Methods

We searched the MEDLINE (1966-July 2011), OVID (1980-July 2011), EMBASE (1980-July 2011), Chinese bio-medical literature & retrieval system (1978-July 2011), Chinese medical current contents (1995-July 2011), and Chinese medical academic conference (1994-July 2011). Studies were included if (1) the study design was a randomised controlled trial (RCT); (2) the study population included cardiac arrest patients who received cardiopulmonary resuscitation and either intravenous magnesium or placebo (0.9% normal saline); (3) the study provided data on return of spontaneous circulation (ROSC) and survival to hospital discharge. Relative risk (RR) and 95% confidence interval (CI) were used to pool the effect.

Results

The study included six RCTs with a total of 531 participants from cardiac arrest. The pooled data demonstrated that ROSC and hospital discharge rates in patients treated with magnesium were 35.5% (95% CI=29.7%-41.3%) and 10.4% (95% CI=6.7%-14.1%) compared with placebo (ROSC rate: 31.3%, 95% CI=25.8%-36.8%; hospital discharge rate: 8.5%, 95% CI=5.2%-11.8%). Administration of intravenous magnesium sulfate could not significantly increase ROSC (RR=1.14, 95% CI=0.91-1.43, P=0.26) and survival to hospital discharge (RR=1.22, 95% CI=0.74-2.02, P=0.43) compared with placebo.

Conclusions

Administration of magnesium sulfate does not improve ROSC and survival to hospital discharge in patients of cardiac arrest.

Amiodarone, lidocaine, magnesium or placebo in shock refractory ventricular arrhythmia: A Bayesian network meta-analysis

Recent evidence challenges, the superiority of amiodarone, compared to other anti-arrhythmic medications, as the agent of choice in pulseless ventricular tachycardia (VT) or ventricular fibrillation (VF). We conducted Bayesian network and traditional meta-analyses to investigate the relative efficacies of amiodarone, lidocaine, magnesium (MgSO4) and placebo as treatments for pulseless VT or VF. Eleven studies [5200 patients, 7 randomized trials (4, 611 patients) and 4 non-randomized studies (589 patients)], were included in this meta-analysis. The search was conducted, from 1981 to February 2017, using MEDLINE, EMBASE and The Cochrane Library. Estimates were reported as odds ratio (OR) with 95% Credible Interval (CrI). Markov chain Monte Carlo (MCMC) modeling was used to estimate the relative ranking probability of each treatment group based on surface under cumulative ranking curve (SUCRA). Bayesian analysis demonstrated that lidocaine had superior effects on survival to hospital discharge, compared to amiodarone (OR, 2.18, 95% Cr.I 1.26-3.13), MgSO4 (OR, 2.03, 95% Cr.I 0.74-4.82) and placebo (OR, 2.42, 95% Cr.I 1.39-3.54). There were no statistical differences among treatment groups regarding survival to hospital admission/24 h (hrs) and return of spontaneous circulation (ROSC). Probability analysis revealed that lidocaine was the most effective therapy for survival to hospital discharge (SUCRA, 97%). We conclude that lidocaine may be the most effective anti-arrhythmic agent for survival to hospital discharge in patients with pulseless VT or VF.

The use of therapeutic magnesium for neuroprotection during global cerebral ischemia associated with cardiac arrest and cardiac surgery in adults: a systematic review

BACKGROUND

Global cerebral ischemia occurs due to reduced blood supply to the brain. This is commonly caused by a cessation of myocardial activity associated with cardiac arrest and cardiac surgery. Survival is not the only important outcome because neurological dysfunction impacts on quality of life, reducing independent living. Magnesium has been identified as a potential neuroprotective agent; however, its role in this context is not yet clear.

OBJECTIVES

The objective of this review was to present the best currently available evidence related to the neuroprotective effects of magnesium during a period of global cerebral ischemia in adults with cardiac arrest or cardiac surgery.

INCLUSION CRITERIA TYPES OF PARTICIPANTS

The current review considered adults aged over 18 years who were at risk of global cerebral ischemia associated with cardiac arrest or cardiac surgery. Studies of patients with existing neurological deficits or under the age of 18 years were excluded from the review.

TYPES OF INTERVENTION(S)/PHENOMENA OF INTEREST

The intervention of interest was magnesium administered in doses of at least of 2 g compared to placebo to adult patients within 24 hours of cardiac arrest or cardiac surgery.

TYPES OF STUDIES

The current review considered experimental designs including randomized controlled trials, non-randomized controlled trials and quasi-experimental designs.

OUTCOMES

The outcome of interest were neurological recovery post-cardiac arrest or cardiac surgery, as measured by objective scales, such as but not limited to, cerebral performance category, brain stem reflexes, Glasgow Coma Score and independent living or dependent living status. To enable assessment of the available data, neuroprotection was examined by breaking down neurological outcomes into three domains - functional neurological outcomes, neurophysiological outcomes and neuropsychological outcomes.

SEARCH STRATEGY

The search strategy aimed to find both published and unpublished studies between January 1980 and August 2014, utilizing the Joanna Briggs Institute (JBI) three-step search strategy. Databases searched included PubMed, Embase, CINAHL, Cochrane Central Register of Controlled Trials, Australian Clinical Trials Register, Australian and New Zealand Clinical Trials Register, Clinical Trials, European Clinical Trials Register and ISRCTN Registry.

METHODOLOGICAL QUALITY

The studies included in this review were of moderate-to-good-quality randomized controlled trials. Studies included measured neurological outcome using functional neurological assessment, neuropsychiatric assessment or neurophysiological assessment.

DATA EXTRACTION

Data were extracted using standardized templates provided by the JBI Meta-analysis of Statistics Assessment and Review Instrument software.

DATA SYNTHESIS

Quantitative data were, where possible, pooled in statistical meta-analysis using Review Manager 5.3 (The Nordic Cochrane Centre, Cochrane; Copenhagen, Denmark). Where statistical pooling was not possible, the findings were presented in narrative form, including tables and figures, to aid in data presentation, where appropriate.

RESULTS

Seven studies with a total of 1164 participants were included in this review. Neurological outcome was categorized into three domains: functional neurological, neurophysiological and neuropsychological outcomes. Meta-analysis of three studies assessing the neuroprotective properties of magnesium administration post cardiac arrest found improved functional neurological outcome (odds ratio 0.44; 95% confidence interval 0.24-0.81).

CONCLUSION

Magnesium may improve functional neurological outcome in patients who suffer global cerebral ischemia associated with cardiac surgery and cardiac arrest. Magnesium does not decrease neuropsychological decline.Further testing of neurological outcomes in the domains of functional outcomes, neurophysiological markers and neuropsychological tests are required to further understanding of the neuroprotective effects of magnesium. Suitable dosing regimens should be investigated prior to introduction into clinical practice. Further research is required to investigate the optimal magnesium dose.

[Which drugs are useful during resuscitation? Which are not?]

INTRODUCTION

Cardiopulmonary resuscitation represents a therapeutic challenge. Evidence-based guidelines, which were updated in 2015, give detailed advice on how to treat the patient.

METHODS

Basic life support consists of cardiopulmonary resuscitation (30 chest compressions interrupted briefly to provide to 2 ventilations) and, if ventricular tachyarrhythmia is present, urgent cardiac defibrillation. Administration of drugs is one of the aspects of advanced life support. Vasopressors (adrenaline, vasopressin) aim to optimize coronary and cerebral perfusion. Antiarrhythmic drugs (amiodarone or lidocaine, when amiodarone is not available) are given during cardiac arrest to treat specific cardiac arrhythmias, mainly ventricular fibrillation and ventricular tachycardia.

CONCLUSION

However, even in current guidelines, there is growing ambivalence towards drug treatment in the setting of cardiopulmonary resuscitation. This is mainly due to a paucity of robust clinical data. Most of the studies that have addressed the efficacy and safety of drugs during resuscitation are observational studies; however, a few small randomized controlled studies also exist. Recently, two large randomized controlled studies addressing the efficacy and safety of adrenaline versus placebo and amiodarone or lidocaine versus placebo have started. Both are currently recruiting patients. The hope is that the results of these studies will help to better define the role of drugs administered during cardiopulmonary resuscitation.

Pharmacotherapy Considerations for the Management of Advanced Cardiac Life Support

Health care providers should be aware of the pharmacotherapy considerations in the American Heart Association's guidelines for advanced cardiac life support (ACLS). Current evidence does not suggest a reduction in mortality with ACLS medications; however, these medications can improve return of spontaneous circulation. Proper agent selection and dosing are imperative to maximize benefit and minimize harm. The latest guideline update included major changes to the ventricular fibrillation/pulseless ventricular tachycardia and pulseless electrical activity/asystole algorithms, which providers should adopt. It is critical that providers be prepared for post-code management. Health care professionals should remain abreast of changing evidence and guidelines.

Antiarrhythmia drugs for cardiac arrest: a systemic review and meta-analysis

INTRODUCTION

Antiarrhythmia agents have been used in the treatment of cardiac arrest, and we aimed to review the relevant clinical controlled trials to assess the effects of antiarrhythmics during cardiopulmonary resuscitation.

METHODS

We searched databases including Cochrane Central Register of Controlled Trials; MEDLINE, and EMBASE. Clinical controlled trials that addressed the effects of antiarrhythmics (including amiodarone, lidocaine, magnesium, and other new potassium-channel blockers) on the outcomes of cardiac arrest were included. Data were collected independently by two authors. The risk ratio of each outcome was collected, and meta-analysis was used for data synthesis if appropriate. Heterogeneity was assessed with the χ² test and the I² test.

RESULTS

Ten randomized controlled trials and seven observational trials were identified. Amiodarone (relative risk (RR), 0.82; 95% confidence interval (CI), 0.54 to 1.24), lidocaine (RR, 2.26; 95% CI, 0.93 to 5.52), magnesium (RR, 0.82; 95% CI, 0.54 to 1.24) and nifekalant were not shown to improve the survival to hospital discharge compared with placebo, but amiodarone, lidocaine, and nifekalant were shown to be beneficial to initial resuscitation, assessed by the rate of return of spontaneous circulation and survival to hospital admission, with amiodarone being superior to lidocaine (RR, 1.28; 95% CI, 0.57 to 2.86) and nifekalant (RR, 0.50; 95% CI, 0.19 to 1.31). Bretylium and sotalol were not shown to be beneficial.

CONCLUSIONS

Our review suggests that when administered during resuscitation, antiarrhythmia agents might not improve the survival to hospital discharge, but they might be beneficial to initial resuscitation. This is consistent with the AHA 2010 guidelines for resuscitation and cardiovascular emergency, but more studies with good methodologic quality and large numbers of patients are still needed to make further assessment.

Clinical trials in cardiac arrest and subarachnoid hemorrhage: lessons from the past and ideas for the future

Introduction. Elevated intracranial pressure that occurs at the time of cerebral aneurysm rupture can lead to inadequate cerebral blood flow, which may mimic the brain injury cascade that occurs after cardiac arrest. Insights from clinical trials in cardiac arrest may provide direction for future early brain injury research after subarachnoid hemorrhage (SAH). Methods. A search of PubMed from 1980 to 2012 and clinicaltrials.gov was conducted to identify published and ongoing randomized clinical trials in aneurysmal SAH and cardiac arrest patients. Only English, adult, human studies with primary or secondary mortality or neurological outcomes were included. Results. A total of 142 trials (82 SAH, 60 cardiac arrest) met the review criteria (103 published, 39 ongoing). The majority of both published and ongoing SAH trials focus on delayed secondary insults after SAH (70%), while 100% of cardiac arrest trials tested interventions within the first few hours of ictus. No SAH trials addressing treatment of early brain injury were identified. Twenty-nine percent of SAH and 13% of cardiac arrest trials showed outcome benefit, though there is no overlap mechanistically. Conclusions. Clinical trials in SAH assessing acute brain injury are warranted and successful interventions identified by the cardiac arrest literature may be reasonable targets of the study.

Biochemical profile and outcomes in trauma patients subjected to open cardiopulmonary resuscitation: a prospective observational pilot study

BACKGROUND

The predictive factors to regain a heartbeat following emergency department resuscitative thoracotomy (EDT) for trauma are poorly understood. The objective of the present study was to prospectively assess the electrolyte profile, coagulation parameters, and acid-base status from intracardiac blood samples in trauma patients subjected to open cardiopulmonary resuscitation (CPR) in the presence of established cardiac arrest.

METHODS

All patients who underwent EDT following trauma were considered for inclusion. Prior to the injection of any resuscitative medications, a sample of intracardiac blood from the right ventricle was obtained for analysis.

RESULTS

During the study period, a total of 22 patients had intracardiac blood samples obtained and were eligible for analysis. Twelve patients never regained cardiac activity, and 10 patients transiently regained a heartbeat for a mean of 51 ± 69 min, but ultimately died. Some 91 % (20/22) of patients presented with severe acidosis (pH < 7.20). The pCO(2) was <45 mmHg in 68 % (15/22) of patients, and the pO(2) level was >75 mmHg in 77 % (17/22) of patients. Patients who never regained cardiac activity had a significantly higher lactate level than those with a return of cardiac rhythm (17.1 ± 2.6 vs. 10.6 ± 4.9 mmol/L, p = 0.018). The sodium and potassium levels were higher for those who never regained a rhythm than for those who did regain a pulse (sodium: 155 ± 14 vs. 147 ± 9 mmol/L, p = 0.094; potassium: 6.0 ± 1.1 vs. 4.6 ± 1.0 mmol/L, p = 0.014). Severe hyperkalemia (potassium > 5.5 mmol/L) occurred significantly more often in patients who did not regain a heart beat (p = 0.030). Coagulopathy (INR > 1.2 and/or prothrombin time >15 s and/or platelet count <100,000/μL) was noted in 96 % of patients.

CONCLUSIONS

Most patients undergoing open CPR have normal blood gas levels. Severe lactic acidosis, hyperkalemia, and hypernatremia are associated with decreased probability for return of cardiac function. Calcium and magnesium levels were not significantly different between the two groups, making the therapeutic role of these electrolytes very questionable.

Current pharmacological advances in the treatment of cardiac arrest

Cardiac arrest is defined as the sudden cessation of spontaneous ventilation and circulation. Within 15 seconds of cardiac arrest, the patient loses consciousness, electroencephalogram becomes flat after 30 seconds, pupils dilate fully after 60 seconds, and cerebral damage takes place within 90–300 seconds. It is essential to act immediately as irreversible damage can occur in a short time. Cardiopulmonary resuscitation (CPR) is an attempt to restore spontaneous circulation through a broad range of interventions which are early defibrillation, high-quality and uninterrupted chest compressions, advanced airway interventions, and pharmacological interventions. Drugs should be considered only after initial shocks have been delivered (when indicated) and chest compressions and ventilation have been started. During cardiopulmonary resuscitation, no specific drug therapy has been shown to improve survival to hospital discharge after cardiac arrest, and only few drugs have a proven benefit for short-term survival. This paper reviews current pharmacological treatment of cardiac arrest. There are three groups of drugs relevant to the management of cardiac arrest: vasopressors, antiarrhythmics, and other drugs such as sodium bicarbonate, calcium, magnesium, atropine, fibrinolytic drugs, and corticosteroids.

The use of antiarrhythmic drugs for adult cardiac arrest: a systematic review

AIMS

In adult cardiac arrest, antiarrhythmic drugs are frequently utilized in acute management and legions of medical providers have memorized the dosage and timing of administration. However, data supporting their use is limited and is the focus of this comprehensive review.

METHODS

Databases including PubMed, Cochrane Library (including Cochrane database for systematic reviews and Cochrane Central Register of Controlled Trials), Embase, and AHA EndNote Master Library were systematically searched. Further references were gathered from cross-references from articles and reviews as well as forward search using SCOPUS and Google scholar. The inclusion criteria for this review included human studies of adult cardiac arrest and anti-arrhythmic agents, peer-review. Excluded were review articles, case series and case reports.

RESULTS

Of 185 articles found, only 25 studies met the inclusion criteria for further review. Of these, 9 were randomised controlled trials. Nearly all trials solely evaluated Ventricular Tachycardia (VT) and Ventricular Fibrillation (VF), and excluded Pulseless Electrical Activity (PEA) and asystole. In VT/VF patients, amiodarone improved survival to hospital admission, but not to hospital discharge when compared to lidocaine in two randomized controlled trials.

CONCLUSION

Amiodarone may be considered for those who have refractory VT/VF, defined as VT/VF not terminated by defibrillation, or VT/VF recurrence in out of hospital cardiac arrest or in-hospital cardiac arrest. There is inadequate evidence to support or refute the use of lidocaine and other antiarrythmic agents in the same settings.

Part 8: adult advanced cardiovascular life support: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care

The goal of therapy for bradycardia or tachycardia is to rapidly identify and treat patients who are hemodynamically unstable or symptomatic due to the arrhythmia. Drugs or, when appropriate, pacing may be used to control unstable or symptomatic bradycardia. Cardioversion or drugs or both may be used to control unstable or symptomatic tachycardia. ACLS providers should closely monitor stable patients pending expert consultation and should be prepared to aggressively treat those with evidence of decompensation.