Michael J. Kellum

Analysis of amplitude spectral area and slope to predict defibrillation in out of hospital cardiac arrest due to ventricular fibrillation (VF) according to VF type: Recurrent versus shock-resistant☆

BACKGROUND In out-of-hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF), VF may recur during resuscitation (recurrent VF) or fail to defibrillate (shock-resistant VF). While retrospective studies have suggested that amplitude spectral area (AMSA) and slope predict defibrillation, it is unknown whether the predictive power is influenced by VF type. We hypothesized that in witnessed OHCA with initial rhythm of VF that the utility for AMSA and slope to predict defibrillation would differ between shock-resistant and recurrent VF. METHODS AMSA and slope were measured immediately prior to each shock. For second or later shocks, VF was classified as recurrent or shock-resistant. Cardiac arrest was classified according to whether the majority of shocks were for recurrent VF or shock-resistant VF. RESULTS 44 patients received 98 shocks for recurrent VF and 96 shocks for shock-resistant VF; 24 patients achieved ROSC in the field. AMSA and slope were higher in recurrent VF compared to shock-resistant VF (AMSA: 28.8±13.1 vs 15.2±8.6 mVHz, P<0.001, and slope: 2.9±1.4 vs 1.4±1.0 mVs(-1), P=0.001). Recurrent VF was more likely to defibrillate than shock-resistant VF (P<0.001). AMSA and slope predicted defibrillation in shock-resistant VF (P<0.001 for both AMSA and slope) but not in recurrent VF. Recurrent VF predominated in 79% of patients that achieved ROSC compared to 55% that did not (P=0.10). CONCLUSIONS In witnessed OHCA with VF as initial rhythm, recurrent VF is associated with higher values of AMSA and slope and is likely to re-defibrillate. However, when VF is shock-resistant, AMSA and slope are highly predictive of defibrillation.

Compression-only cardiopulmonary resuscitation for bystanders and first responders.

Purpose of reviewThe current resuscitation guidelines consider ventilation and chest compression essential components of resuscitation and therefore only one methodology, standard cardiopulmonary resuscitation, is explicitly recommended for the treatment of both respiratory and cardiac arrests. Pathophysiological and experimental observations argue that this generalization results in suboptimal treatment for victims of cardiac arrest. Recent findingsFor more than a decade animal studies have demonstrated that assisted ventilation is not essential during the initial treatment of a fibrillatory arrest; but only in the last year have these results been confirmed in humans. These new observations come from a handful of systems utilizing cardiocerebral resuscitation in their prehospital resuscitation of adult victims of presumed cardiac arrest. They have all demonstrated a dramatic increase in survival. Recent data also indicate that survival is significantly increased when laypersons perform chest-compression-only cardiopulmonary resuscitation. SummaryThe current resuscitation guidelines regarding the prehospital treatment of victims of adult cardiac arrest should be modified to explicitly permit the use of continuous-chest-compression cardiopulmonary resuscitation.

Advancing resuscitation science.

Purpose of reviewTo describe an alternative approach for improving survival of patients with out-of-hospital cardiac arrest (OHCA). The survival of patients with OHCA has been poor and relatively unchanged for decades in spite of recurrent national and international guidelines. Although there are exceptions, many thought and continue to think that any change in the guidelines for cardiopulmonary resuscitation should be based on randomized controlled trials in humans. However, many factors, including the need for informed consent, the marked variability of patients, and the variability of the type and quality of bystander and advanced resuscitation efforts, all make such studies problematic. Thus, potentially life-saving procedures are often withheld for decades, resulting in unnecessary loss of life. Recent findingsMany improvements in public health conditions have been made using models of continuous quality improvement. When applied to resuscitation science, once baseline data are obtained, changes based on reliable experimental findings are instituted and outcomes measured. This approach has now been shown to result in significant improvement in neurologically intact survival of patients with OHCA. SummaryFollowing this model, we found significant improvement in survival of patients with a witnessed OHCA primary cardiac arrest.

Improving performance of emergency medical services personnel during resuscitation of cardiac arrest patients: the McMAID approach.

Purpose of reviewThe article presents the method we developed to improve emergency medical service personnel training. Recent findingsFollowing the introduction of new prehospital protocol for emergency medical services that initially dramatically improved survival of patients with witnessed out-of-hospital cardiac arrest, we found that without an adequate training and retraining program, survival rates decreased. A new training methodology called McMAID was developed to improve the quality of the resuscitation effort. SummaryIt is possible to train personnel to routinely execute an organized resuscitation if the approach to training is modified.