# 5262
Yep, that’s me - circa 1976 with my (now museum piece) LifePak 5 (and an almost full head of hair).
While I try not to tell paramedic `war stories’, or go out of my way to make this blog about me, every once in awhile I can’t resist throwing in a personal anecdote.
In August of 1974 I was among the first 36 D.O.T. paramedic graduates in the state of Florida. With portable defibrillators, IVs, Cardiac meds, and radio telemetry on board - everyone expected us to start saving lives left and right.
And while our `saves’ went up, they didn’t go up as dramatically as many hoped.
Sure, we had some great saves - particularly among younger patients, drowning victims, and trauma.
But overall, our cardiac arrest success rate was dismal. Perhaps now, after all these years, we may have a better clue why.
First, a quickie lesson in heart attacks and EKGs (the readout of the electrical activity of the heart).
In a cardiac arrest, the patient is pulseless, usually non-breathing, and unable to circulate oxygenated blood to the brain and other organs. Death follows generally in 4 to 10 minutes.
But not all pulseless arrests are created equal.
This is bad.
(Ventricular Tachycardia)
This is very bad
(Ventricular Fibrillation)
And this is worst of all.
(Asystole)
The first two rhythms strips are considered `shockable’ arrhythmias. The heart may not be beating, but there is still some (albeit, chaotic) electrical activity going on.
Applying an electrical shock promptly enough can often restore NSR (normal sinus rhythm) to a stopped heart.
But despite what you may have seen in the movies, and on television, you can shock an asystolic (flatlined) heart all day long without much hope of success.
There are some cardiac meds that can (rarely) convert asystole to fibrillation, but defibrillation alone is generally futile.
Yesterday the NIH announced a study comparing the type of cardiac arrests experienced by people at home verses people who collapsed in public.
And the results are fascinating. At least to an old EMT-II like myself.
First, some excerpts from the press release, then a link to the NEJM study, after which I’ll be back with a little more.
Shockable cardiac arrests are more common in public than home
Comprehensive NIH study helps explain discrepancy in survival rates between cardiac arrests in public and at home
Cardiac arrests that can be treated by electric stimulation, also known as shockable arrests, were found at a higher frequency in public settings than in the home, according to a National Institutes of Health-funded study appearing in the Jan. 27 issue of the New England Journal of Medicine.
The study compared home and public cardiac arrests under various scenarios. For example, the study considered whether bystanders or emergency medical services (EMS) personnel witnessed the cardiac arrest, and whether the person experiencing the arrest received treatment with an automatic external defibrillator (AED).
In every scenario, a higher percentage of public cardiac arrests were classified as ventricular tachycardia (VT) or ventricular fibrillation (VF), the types of abnormal heart rhythms that can be treated by electric shock.
More than one-third of the people who had a cardiac arrest in public and were treated with an AED survived. This is a significant improvement over the roughly 8 percent national average of cardiac arrest survival. In comparison, the overall survival for home-occurring cardiac arrests treated with an AED was 12 percent.
Ventricular Tachyarrhythmias after Cardiac Arrest in Public versus at Home
Myron L. Weisfeldt, M.D., Siobhan Everson-Stewart, Ph.D., Colleen Sitlani, M.S., Thomas Rea, M.D., Tom P. Aufderheide, M.D., Dianne L. Atkins, M.D., Blair Bigham, M.Sc., Steven C. Brooks, M.D., M.H.Sc., Christopher Foerster, M.Sc., Randal Gray, M.A.Ed., Joseph P. Ornato, M.D., Judy Powell, B.S.N., Peter J. Kudenchuk, M.D., and Laurie J. Morrison, M.D. for the Resuscitation Outcomes Consortium (ROC) Investigators
N Engl J Med 2011; 364:313-321January 27, 2011
Like all studies, there are limitations to this one.
Some assumptions regarding the arrhythmias of successfully cardioverted arrest victims using AEDs (which only shock when they detect VT or VF) had to be made in lieu of actual EKG strips.
Likewise, home heart attacks (where AEDs are less likely to be found, or the patient’s collapse witnessed) may have started with VT or VF and progressed to asystole by the time rescuers with their EKGs arrived.
But even when you take these items into account, it appears that cardiac arrests that occur in public are far more likely to be a `shockable’ (VT or VF) rhythm than those that occur in the home.
This likely has more to do with the age, and physical condition of the patient, than the actual location. Those who are able to be out and about are probably in somewhat better overall health than those who are house bound.
All of which points out the benefits of putting more AEDs in public places, and promoting lay person CPR and AED training.
The authors of this NEJM report conclude:
Conclusions
Regardless of whether out-of-hospital cardiac arrests are witnessed by EMS personnel or bystanders and whether AEDs are applied by bystanders, the proportion of arrests with initial ventricular fibrillation or pulseless ventricular tachycardia is much greater in public settings than at home. The incremental value of resuscitation strategies, such as the ready availability of an AED, may be related to the place where the arrest occurs. (Funded by the National Heart, Lung, and Blood Institute and others.)
For more on the recent changes to bystander CPR, you may wish to visit these recent blogs.
CPR As A Requirement For High School Graduation
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