Selected controversies in cardiopulmonary resuscitation

Effect of sodium bicarbonate on functional outcome in patients with out-of-hospital cardiac arrest: a post-hoc analysis of a French and North-American dataset

BACKGROUND AND IMPORTANCE

No large randomised controlled trial has assessed the potential benefits on neurologic outcomes of prehospital sodium bicarbonate administration in patients with nontraumatic out-of-hospital cardiac arrest (OHCA).

OBJECTIVE

To obtain information of assistance in designing a randomised controlled trial of bicarbonate therapy after OHCA in specific patient subgroups.

DESIGN

We conducted two, separate, simultaneous, retrospective studies of two distinct, unlinked datasets.

SETTING AND PARTICIPANTS

One dataset was a French nationwide population-based registry (RéAC Registry, French dataset) and the other was a randomised controlled trial comparing continuous to interrupted chest compressions in North America (ROC-CCC trial, North-American dataset).

INTERVENTION

We investigated whether prehospital bicarbonate administration was associated with better neurologic outcomes.

OUTCOME MEASURES AND ANALYSES

The main outcome measure was the functional outcome at hospital discharge. To adjust for potential confounders, we conducted a nested propensity-score-matched analysis with inverse probability-of-treatment weighting.

MAIN RESULTS

In the French dataset, of the 54 807 patients, 1234 (2.2%) received sodium bicarbonate and 450 were matched. After propensity-score matching, sodium bicarbonate was not associated with a higher likelihood of favourable functional outcomes on day 30 [adjusted odds ratio (aOR), 0.912; 95% confidence interval (95%CI), 0.501-1.655]. In the North-American dataset, of the 23 711 included patients, 4902 (20.6%) received sodium bicarbonate and 1238 were matched. After propensity-score matching, sodium bicarbonate was associated with a lower likelihood of favourable functional outcomes at hospital discharge (aOR, 0.45; 95% CI, 0.34-0.58).

CONCLUSION

In patients with OHCA, prehospital sodium bicarbonate administration was not associated with neurologic outcomes in a French dataset and was associated with worse neurologic outcomes in a North-American dataset. Given the considerable variability in sodium bicarbonate use by different prehospital care systems and the potential resuscitation-time bias in the present study, a large randomised clinical trial targeting specific patient subgroups may be needed to determine whether sodium bicarbonate has a role in the prehospital management of prolonged OHCA.

Sodium bicarbonate on severe metabolic acidosis during prolonged cardiopulmonary resuscitation: a double-blind, randomized, placebo-controlled pilot study

Background

Sodium bicarbonate administration during cardiopulmonary resuscitation (CPR) is controversial. Current guidelines recommend sodium bicarbonate injection in patients with existing metabolic acidosis, but clinical trials, particularly, those involving patients with acidosis, are limited. We aimed to evaluate the efficacy of sodium bicarbonate administration in out-of-hospital cardiac arrest (OHCA) patients with severe metabolic acidosis during prolonged CPR.

Methods

Prospective, double-blind, randomized placebo-controlled pilot trial was conducted between January 2015 and December 2015, at a single center emergency department (ED). After 10 minutes of CPR, patients who failed to achieve return of spontaneous circulation (ROSC) and with severe metabolic acidosis (pH<7.1 or bicarbonate <10 mEq/L) were enrolled. Sodium bicarbonate (n=25) or normal saline (n=25) were administered. The primary end point was sustained ROSC. The secondary end points were the change of acidosis and good neurologic survival.

Results

Sodium bicarbonate group had significant effect on pH (6.99 vs. 6.90, P=0.038) and bicarbonate levels (21.0 vs. 8.0 mEq/L, P=0.007). However, no significant differences showed between sodium bicarbonate and placebo groups in sustained ROSC (4.0% vs. 16.0%, P=0.349) or good neurologic survival at 1 month (0.0% vs. 4.0%, P=1.000).

Conclusions

The use of sodium bicarbonate improved acid-base status, but did not improve the rate of ROSC and good neurologic survival. We could not draw a conclusion, but our pilot data could be used to design a larger trial to verify the efficacy of sodium bicarbonate.

Trial Registration

NCT02303548 (http://www.ClinicalTrials.gov).

Resuscitation Outcomes Consortium-Amiodarone, Lidocaine or Placebo Study (ROC-ALPS): Rationale and methodology behind an out-of-hospital cardiac arrest antiarrhythmic drug trial

BACKGROUND

Despite their wide use, whether antiarrhythmic drugs improve survival after out-of-hospital cardiac arrest (OHCA) is not known. The ROC-ALPS is evaluating the effectiveness of these drugs for OHCA due to shock-refractory ventricular fibrillation or pulseless ventricular tachycardia (VF/VT).

METHODS

ALPS will randomize 3,000 adults across North America with nontraumatic OHCA, persistent or recurring VF/VT after ≥1 shock, and established vascular access to receive up to 450 mg amiodarone, 180 mg lidocaine, or placebo in the field using a double-blind protocol, along with standard resuscitation measures. The designated target population is all eligible randomized recipients of any dose of ALPS drug whose initial OHCA rhythm was VF/VT. A safety analysis includes all randomized patients regardless of their eligibility, initial arrhythmia, or actual receipt of ALPS drug. The primary outcome of ALPS is survival to hospital discharge; a secondary outcome is functional survival at discharge assessed as a modified Rankin Scale score ≤3.

RESULTS

The principal aim of ALPS is to determine if survival is improved by amiodarone compared with placebo; secondary aim is to determine if survival is improved by lidocaine vs placebo and/or by amiodarone vs lidocaine. Prioritizing comparisons in this manner acknowledges where differences in outcome are most expected based on existing knowledge. Each aim also represents a clinically relevant comparison between treatments that is worth investigating.

CONCLUSIONS

Results from ALPS will provide important information about the choice and value of antiarrhythmic therapies for VF/VT arrest with direct implications for resuscitation guidelines and clinical practice.

Vasopressin improves outcome in out-of-hospital cardiopulmonary resuscitation of ventricular fibrillation and pulseless ventricular tachycardia: a observational cohort study

INTRODUCTION

An increasing body of evidence from laboratory and clinical studies suggests that vasopressin may represent a promising alternative vasopressor for use during cardiac arrest and resuscitation. Current guidelines for cardiopulmonary resuscitation recommend the use of adrenaline (epinephrine), with vasopressin considered only as a secondary option because of limited clinical data.

METHOD

The present study was conducted in a prehospital setting and included patients with ventricular fibrillation or pulseless ventricular tachycardia undergoing one of three treatments: group I patients received only adrenaline 1 mg every 3 minutes; group II patients received one intravenous dose of arginine vasopressin (40 IU) after three doses of 1 mg epinephrine; and patients in group III received vasopressin 40 IU as first-line therapy. The cause of cardiac arrest (myocardial infarction or other cause) was established for each patient in hospital.

RESULTS

A total of 109 patients who suffered nontraumatic cardiac arrest were included in the study. The rates of restoration of spontaneous circulation and subsequent hospital admission were higher in vasopressin-treated groups (23/53 [45%] in group I, 19/31 [61%] in group II and 17/27 [63%] in group III). There were also higher 24-hour survival rates among vasopressin-treated patients (P < 0.05), and more vasopressin-treated patients were discharged from hospital (10/51 [20%] in group I, 8/31 [26%] in group II and 7/27 [26%] group III; P = 0.21). Especially in the subgroup of patients with myocardial infarction as the underlying cause of cardiac arrest, the hospital discharge rate was significantly higher in vasopressin-treated patients (P < 0.05). Among patients who were discharged from hospital, we found no significant differences in neurological status between groups.

CONCLUSION

The greater 24-hour survival rate in vasopressin-treated patients suggests that consideration of combined vasopressin and adrenaline is warranted for the treatment of refractory ventricular fibrillation or pulseless ventricular tachycardia. This is especially the case for those patients with myocardial infarction, for whom vasopressin treatment is also associated with a higher hospital discharge rate.

Prehospital management of cardiac arrest: how useful are vasopressor and antiarrhythmic drugs?

Out-of-hospital resuscitation protocols for patients suffering cardiac arrest have historically included cardiopulmonary resuscitation, defibrillation, and rapid transport to a hospital. For many years, use of drugs to improve myocardial perfusion or to correct arrhythmias that occur during cardiac arrest has been part of prehospital efforts to revive patients in ventricular tachycardia or ventricular fibrillation. Use of some of these drugs, however, may be based more on tradition than on well-documented evidence of efficacy. The authors reviewed pertinent data on the vasopressors epinephrine and vasopressin and the antiarrhythmics amiodarone and lidocaine to evaluate the usefulness of these drugs in cardiac arrest. They found little clinical data supporting the prehospital use of lidocaine in cardiac arrest, and despite a great deal of laboratory and clinical data addressing the efficacy of epinephrine, there is no large, randomized, controlled clinical trial supporting its use. Data on amiodarone and vasopressin support the use of these drugs in out-of-hospital resuscitation efforts.