'No significant improvement': new study
Research recently published in the journal Resuscitation has examined the effectiveness of Double Sequential Defibrillation (DSD) in cardiac arrest management across Aotearoa New Zealand, finding the technique did not demonstrate a significant improvement in survival rates.
DSD is a new approach to cardiac arrest used when standard treatment isn’t working. It involves delivering two rapid shocks from two defibrillators, with pads placed in different positions on the chest, to attempt to restart the heart when it remains in a life-threatening rhythm despite multiple attempts.
A study in Canada showed survival rates increased when DSD was used, but this study - Implementation of double sequential defibrillation (DSD): an Aotearoa New Zealand observational study - was unable to replicate those results.
In 2023, Aotearoa New Zealand became one of the first countries in the world to introduce DSD into routine ambulance care. That created a rare opportunity to examine how this promising but still uncertain treatment works in real-world practice, says Associate Professor Bridget Dicker, lead author on the new paper.
Dicker, who is Head of Department – Paramedicine at AUT, says DSD was introduced because cardiac arrest that doesn’t respond to usual treatment is one of the most challenging situations first responders face.
"There’s been a lot of international interest, but very little evidence on how it actually performs in day-to-day care.”
The national study analysed more than 1,400 cardiac arrest cases before and after DSD was introduced, including comparisons between patients who did and did not receive the treatment.
The findings highlight just how complex these cases are, Dicker says.
“What we’re seeing is that DSD is often used in the sickest patients, those who haven’t responded to anything else. That makes it difficult to tell whether the treatment itself is making a difference, or whether it’s simply being used as a last resort.”
The study also suggests that timing may matter, with later use of DSD linked to poorer outcomes, although this likely reflects the challenges of treating patients whose hearts have remained stopped for longer.
“This is not the end of the story for DSD, far from it,” Dicker says. “It’s still a promising approach, but we need to better understand when to use it and which patients are most likely to benefit.”
Cardiac arrest is when the heart suddenly stops beating. Without immediate treatment, it is fatal within minutes. The greatest gains in survival continue to come from early recognition, bystander CPR, and rapid community defibrillation, making these the cornerstones of any effective cardiac arrest response.
Useful links
- A new emergency procedure for cardiac arrests aims to save more lives – here’s how it works
- Bridget Dicker’s academic staff profile
- Paramedicine at AUT
- Implementation of double sequential defibrillation (DSD): an Aotearoa New Zealand observational study
- Defibrillation Strategies for Refractory Ventricular Fibrillation – New England Journalism of Medicine
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