In this edition of PTM Journal Club explore the impact of bag-valve-mask ventilation as well as the use of lidocaine and/or amiodarone on the survivability of out-of-hospital cardiac arrest.
Bag-Valve-Mask Ventilation and Survival From Out-of-Hospital Cardiac Arrest: A Multicenter Study
Background and Objectives
Around 60,000 out-of-hospital cardiac arrests (OHCA) occur in Canada each year, which equates to one every nine minutes. Multiple large-scale observational and experimental studies have informed CPR guidelines on the best practices for delivering chest compressions; however, this skill alone does not generate sufficient tidal volume for gas exchange. Adjuncts to delivering adequate ventilation include using a BVM device to provide enough volume to achieve a visible chest rise. Ventilation metrics have not been investigated because there have been no methods to measure ventilation in a pre-hospital setting. The objectives of this study were to determine the incidence of bioimpedance-detected ventilation waveforms in 30:2 CPR during BVM ventilation and to assess the association of ventilation with outcomes from OHCAs.
Methods
The authors studied patients with an out-of-hospital cardiac arrest from six sites of the Resuscitation Outcomes Consortium (ROC) CCC (Continuous Compressions versus Standard CPR in Patients with Out-of-Hospital Cardiac Arrest) trial. They analyzed patients assigned to the 30:2 CPR arm with ≥2 minutes of thoracic bioimpedance signal recorded with a cardiac defibrillator. Detectable ventilation waveforms were defined as having a bioimpedance amplitude ≥0.5 Ω (corresponding to ≥250 mL) and a duration ≥1 s. They compared the incidence of ventilation and outcomes in 2 groups:
- Patients with ventilation waveforms in <50% of pauses
- Patients with ventilation waveforms in ≥50% of pauses
The primary outcome was survival to hospital discharge. Secondary outcomes were ROSC at any time, pre-hospital ROSC, ROSC on arrival at the emergency department, survival to hospital admission, and survival with a favourable neurological outcome (modified Rankin Scale score ≤3) at hospital discharge.
Authors’ Conclusions
Lung inflation occurs infrequently with BVM ventilation during pre-hospital resuscitation with 30:2 CPR for OHCAs. Ventilation with measurable lung inflation in ≥50% of pauses was associated with increased rates of ROSC and survival with a favourable neurological outcome.
Limitations
This study was a retrospective secondary analysis of the well-known parent study, ROC CCC. Although a well-conducted study, the data was only from two devices as several brands either did not have bioimpedance or the recording was of insufficient quality. Further, patient characteristics, including a high BMI, may affect bioimpedance amplitude and the detection of ventilation waveforms.
Bottom Line
This study demonstrates the importance of providing adequate ventilation with a BVM device to improve cardiac arrest outcomes. All emergency care providers need to be proficient in this skill, as most ventilations in this study were ineffective. Future prospective studies on ventilation strategies during cardiac arrest will help guide care provided in the pre-hospital setting.
Full Citation
Survival by time-to-administration of amiodarone, lidocaine, or placebo in shock-refractory out-of-hospital cardiac arrest
Background and Objectives
Out-of-hospital cardiac arrests are a leading cause of mortality, with more than 80,000 patients having an initial shockable rhythm (VF/pVT). Current ACLS guidelines have either amiodarone or lidocaine as options for antiarrhythmics during shockable cardiac arrests. However, the optimal timing of antiarrhythmics is lacking, and administration timing can vary widely. The objectives of this study were to evaluate if early antiarrhythmic administration was associated with higher survival and survival with a favourable neurologic outcome for patients with shockable OHCAs compared to a normal saline placebo.
Methods
This is a secondary analysis of the 10-site, 55-EMS-agency double-blind randomized controlled amiodarone, lidocaine, or placebo (ALPS trial). The researchers included patients with initial shockable rhythms who received amiodarone, lidocaine, or placebo before achieving ROSC. They performed logistic regression analyses evaluating survival to hospital discharge as the primary outcome, and the secondary outcomes included survival to admission and functional survival (modified Rankin scale score ≤ 3). Further, they evaluated the samples stratified by early (<8 min) and late administration groups (≥8 min). They compared outcomes for amiodarone and lidocaine compared to placebo and adjusted for potential confounders.
Authors’ Conclusions
Early administration of amiodarone, particularly within 8 minutes, is associated with increased survival to admission, survival to discharge, and functional survival compared to placebo in patients with an initial shockable rhythm.
Limitations
This study was a secondary analysis of the ALPS trial, which was not designed to study the effects of medication timing. There is possible selection bias as the patients enrolled could have had little chance of survival. The dataset contains a small amount of IO delivery of medication, which affects the impact of antiarrhythmic efficacy. The ALPS data set does not have information on certain potential confounding factors (i.e. CPR fraction/pauses, patient comorbidities, etc.). The authors could not adjust for clustering by agency or site as this data was not available in the ALPS data set (cannot evaluate if further timing stratification resulted in differences across the sites).
Bottom Line
Patients who received amiodarone within 8 minutes or with initial epinephrine had greater survival rates with favourable neurological outcomes. Future prospective studies to determine if amiodarone, given earlier than in the current ACLS algorithm, improves patient outcomes.
Full Citation
For more content like this, check-out other PTM Journal Club recaps, by clicking HERE.
