Dr Ian Drennan

Ian Drennan has a PhD in clinical medicine from the University of Toronto with a focus on resuscitation sciences. He works as an Advanced Care Paramedic with York Region Paramedic Services and an instructor with Sunnybrook Centre for Prehospital Medicine. Ian also holds a part-time faculty position in the health sciences department at Georgian College. His thesis is focused on the development of clinical prediction rules and the treatment of out-of-hospital cardiac arrest patients. Other research interests include clinical aspects of prehospital care including community paramedicine, trauma, and sepsis. He is experienced in research methodology in systematic reviews, observational research through the use of large epidemiologic datasets, and randomized controlled trials in the prehospital setting. Ian has received funding from the Canadian Institute of Health Research (CIHR) and the Heart and Stroke Foundation of Canada, and is the past recipient of a 2014 Young Investigator Award from the American Heart Association. In addition to his PhD work, Ian is a member of a number of committees related to paramedic practice and research. He currently sits as a member of the International Liaison Committee of Resuscitation (ILCOR) Advanced Life Support (ALS) taskforce. and a writing group member for the 2015 and 2020 American Heart Association Guidelines for CPR and ECC. Ian can be reached at ian.drennan@sunnybrook.ca . Follow Ian on Twitter @IanR_Drennan. View his research on PubMed, ResearchGate or ResearcherID

We’ve optimized and delivered high performance resuscitation, incorporated the best evidence-based medicine, but our patient is still in a refractory ventricular fibrillation. What, if any, options do we have next?

Currently, we continue to shock every 2 minutes and administer more antiarrhythmics and epinephrine until we pronounce or transport. Researchers at Sunnybrook Health Science Centre in Toronto, Canada, are conducting a randomized controlled trial with paramedic services in Ontario to examine double sequential external defibrillation (DSED) as an additional intervention to help patients in refractory shockable rhythms. The DOuble Sequential External Defibrillation for Refractory Ventricular Fibrillation (DOSE VF) RCT (clinicaltrials.gov: NCT04080986)

There are several theories that suggest why double sequential defibrillation and/or vector change defibrillation may be effective.

1. Energy theory: increased energy delivery allows for defibrillation of a critical mass of myocardium terminating the refractory VF.
2. Setting up theory: the first shock reduces the threshold and results in a more successful second shock.
3. Multiple vector theory: change in pads (or additional pads) changes the energy vector defibrillating parts of myocardium not adequately defibrillated in standard position.

The initial phase of the DOSE VF RCT was conducted as a pilot study, that enrolled approximately 150 patients. Since the study is ongoing, the main outcome (survival to hospital discharge) cannot be reported, however the pilot determined DSED to be feasible and safe.

Interestingly, the early data from the pilot study shows that the rates of VF termination and ROSC were quite a bit higher in the groups that got double sequential defibrillation and those that got vector change, compared to those that got standard (anterolateral pad placement) treatment.