Innovative Cardiac Arrest Treatment in New Zealand Holds Promise : ScienceAlert

Aotearoa New Zealand has become the second nation worldwide, following Canada, to roll out a revolutionary procedure for cardiac arrest patients beginning in January. This significant advancement is known as “double sequential external defibrillation” (DSED) and is anticipated to reshape emergency response protocols while enhancing survival odds for certain cases.

Outcomes for cardiac arrest survival are significantly dependent on prompt and efficient resuscitation efforts. The heart’s muscle walls are normally stimulated by electrical impulses to contract in a synchronized manner.

However, when these electrical rhythms are disrupted, the result can be ineffectual and irregular heartbeats or a complete cessation, thus leading to cardiac arrest.

Defibrillation is a fundamental resuscitation technique. It works by delivering a potent electric shock to the heart to halt the abnormal electrical activity, enabling the heart to reinstate its usual rhythm.

The effectiveness of a defibrillation relies on the type of underlying heart rhythm issue and the correct placement of the defibrillation pads that administer the shock. The new procedure introduces a second choice when standard positioning fails to work efficiently.

Implementing Twin Defibrillators

In traditional defibrillation practices, one pad is applied below the right side of the chest near the collarbone, and the other pad under the left armpit. The process consists of administering shocks at two-minute intervals.

Swift defibrillation can substantially enhance the odds of surviving a cardiac arrest. Yet about 20% of patients suffering from cardiac arrest due to “ventricular fibrillation” or “pulseless ventricular tachycardia” are unresponsive to standard defibrillation techniques. These conditions involve irregular ventricular heart activity.

DSED presents a groundbreaking approach, administering rapid consecutive shocks through two defibrillators with pads placed in distinct locations—one on the chest’s front and side, the other across the front and back.

An operator simultaneously activates the defibrillators sequentially, moving one hand from the first device to the second. A pivotal randomised trial conducted in Canada demonstrated that DSED could potentially more than double the survival probability for patients with ventricular fibrillation or pulseless ventricular tachycardia who do not respond to regular shocks.

The introduction of a second shock is believed to enhance the chance of eradicating the lingering abnormal electrical activity, thereby directing more energy to the heart via a different passageway closer to the heart’s left ventricle.

Evidence for the Effectiveness of DSED

Analyses of New Zealand ambulance records from 2020 to 2023 noted approximately 1,390 individuals who might benefit from innovative defibrillation techniques. The survival rate within this subset is currently a mere 14%.

In light of the promising potential of DSED to significantly elevate survival rates for these patients, the National Ambulance Sector Clinical Working Group has revised the emergency medical services clinical procedures and guidelines.

According to these updated guidelines, if ventricular fibrillation or pulseless ventricular tachycardia persists after administering two standard defibrillation shocks, the DSED approach should be applied. This requires the availability of two defibrillators as well as relevant training for staff in this new method.

While powerful, the evidence supporting DSED until now stemmed mainly from theoretical understanding and a number of limited observational studies. The experiment in Canada marked the first head-to-head comparison between DSED and the standard protocol.

Within a pool of 261 patients, the survival rate under the DSED strategy was 30.4%, in contrast to a 13.3% survival rate when traditional resuscitation protocols were followed.

The trial’s design reduced the interference of confounding variables, instilling confidence that the improvement in survival was directly due to the defibrillation method rather than disparities in regional resources or training.

This research also supports prior theoretical and clinical data, although the study goals were partially hindered by early termination due to the COVID-19 pandemic, consequently recruiting less than half of the intended sample size.

Yet, facing these limitations, a renowned international panel of resuscitation advisors updated its recommendations in 2023 following the trial data, advising (with caution) that emergency medical services should contemplate DSED for patients with ventricular fibrillation or pulseless ventricular tachycardia unresponsive to standard interventions.

Preparation and Rollout

Despite the nascent state of the evidence, adopting DSED by New Zealand’s emergency services carries implications beyond national patient care. This is a crucial move towards enhancing the global understanding of optimal resuscitation tactics.

Adapting a procedure from research settings to real-world applications is always tricky. However, the decision to amend practices for patients with a low survival rate under current treatments was made after thoroughly evaluating the evidence at hand.

Prior to DSED utilization, emergency medical workers must undertake compulsory training, education, and simulation exercises. The success of the implementation is closely observed to gauge its influence.

Hospitals and emergency units have been made aware of the procedural changes and have been provided with opportunities for inquiry and feedback. In line with the change, St John’s ambulance service will execute case assessments alongside broader monitoring to maintain patient safety as a priority.

There is cautious optimism among the medical community that this alteration in cardiac arrest management will yield positive effects on patient survival outcomes in New Zealand.

Vinuli Withanarachchie, PhD candidate, College of Health, Massey University; Bridget Dicker, Associate Professor of Paramedicine, Auckland University of Technology, and Sarah Maessen, Research Associate, Auckland University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.