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CASS: What a Registry Reveals About Cardiac Arrest in Victoria

A well-done cardiac arrest registry can tell you so much more than just who’s surviving. The one they have in Victoria, Australia, has informed copious research that’s helping improve bystander CPR rates and other essential aspects of resuscitation.

Prof. Karen Smith, PhD, outlined some of that Thursday at the Cardiac Arrest Survival Summit in Seattle. Smith is an epidemiologist, director of the Center for Research and Evaluation at Ambulance Victoria, and an adjunct professor at Monash University. She’s also chair of VACAR, the Victorian Ambulance Cardiac Arrest Registry.

Now two decades old, VACAR collects data on all cardiac arrests in the state and has amassed around 110,000 cases. It includes more than 300 variables, Utstein elements and more, and discharge data from more than 100 participating hospitals. In 2010 it added a 12-month follow-up question regarding survivors’ quality of life—one of few registries to collect such data. New fields look at high-performance CPR (compression fraction, pauses, rate and depth), call-takers (time to recognition, time to hands-on-chest instructions), and bystanders (relationship to victim, medical qualifications).

The incidence of cardiac arrest in Victoria is increasing in rural areas and relatively stable in the cities (around 70% of the state’s 6.4 million residents live in Melbourne). But since initiation of VACAR, CPR rates have improved from 59% to 76% in all cases, 48% to 62% in bystander-witnessed cases, and 28% to 39% among bystander-witnessed victims who were resuscitated.

With bystander CPR in Victoria, overall resuscitation is 31%. Without, it’s 23%. With it, 14% are discharged from hospitals alive. Without it, just 4%. Your adjusted odds of survival in Victoria, Smith said, are threefold greater with bystander CPR.

You can’t manage what you can’t measure, and data like this can inform and facilitate tracking of initiatives to drive improvement, the impact of implemented programs, locations to prioritize, and individual medic exposure and skills maintenance. VACAR has enabled CPR-specific research to examine areas of high incidence and low bystander assistance, call-taker instructions and language, barriers to CPR, who’s delivering bystander CPR, its impact on responders, and the impact of public-access defibrillation programs.

Smith summarized a number of studies of specific aspects of bystander CPR conducted using VACAR data. Among them, researchers looking at those areas of high OHCA incidence but low bystander CPR rates identified a threefold difference in the former among local government areas and a 25% variation in the latter. Those patterns persisted over time, validating the use of retrospective data for registry studies.

What drove those variations? Unsurprisingly, predictors of higher OHCA incidence included proportion of the population over age 65, socioeconomic status, education level, and prevalence of smoking. Bystander CPR rates were solid, from 63% to 73%, but only population density emerged as predictive. Comparing areas of high and low bystander rates found, not surprisingly, an association between rates and training.

Barriers to performing CPR fell into three areas: procedural (e.g., language issues, landline phones not near victims), CPR knowledge (skills deficit, feeling it won’t help), and personal (barriers such as physical limitations or panic). Simplifying dispatch instructions made a difference: Changing telephone instructions to giving 400 compressions before any rescue breaths improved both bystander CPR rates and victim survival.

Language matters. Other investigators found dispatchers receiving qualified responses to the question “Are they breathing?” (e.g., “Yes, but…” as in agonal respirations) typically coded those answers as simple yeses. And when prompting bystanders to perform CPR, dispatchers fared better with directions (i.e., “We’re going to,” “We need to”) than requests (“Would you,” “Are you willing”).

Data also showed the value of public access defibrillation. When OHCA patients’ first shocks were delivered by Ambulance Victoria staff, 51% were resuscitated and 30% discharged alive. When that shock came from first responders, the numbers improved to 68% and 36%. And when it came from a public AED, 56% of recipients were discharged alive. Those shocked via PAD also did better than those shocked by EMS in 12-month quality-of-life measures such as living at home without care and returning to work.

For more from VACAR, see https://www.ambulance.vic.gov.au/about-us/research/research-publications/.

John Erich is the senior editor of EMS World.

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