Another One Bites the Dust (Part 2)

In Part 1 we talked about some of the improvements made to CPR guidelines over the years. In Part 2 we will discuss some of the modifications we may see formally implemented in the future. Some of these ideas may be reasonably incorporated into our current practice despite not being officially outlined. (And some ideas are ridiculous but fun to dream about).

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Introducing Impedance Threshold Devices

First, here is the best written explanation I’ve come across about what exactly an ITD does.

“Impedance Threshold Devices (ITD) have been given a Class IIa recommendation by the American Heart Association (AHA)… IDT’s are designed to aid rescuers in enhancing circulation for patients receiving assisted ventilation during CPR.

IDT’s, such as ResQPOD®, utilizes the interdependence of the respiratory and circulatory systems to create a negative pressure within the thorax during the release phase of CPR. This increase in negative pressure results in drawing more blood into the chest and increasing venous return to the heart. The improved blood return to the heart improves cardiac output on the subsequent compression.” 2

And here is a demonstration video of a ResQPOD being used on a pig…

Despite the neat! factor of this device, AHA cautions that, “Use of the impedance threshold device improved ROSC and short-term survival in adults with out-of-hospital cardiac arrest, but it has not improved long-term survival in patients with cardiac arrest.” That being said, as a pre-hospital provider, I wouldn’t mind getting my paws on one.

Perishock Pause Reduction

Perishock pauses are defined as pauses in chest compressions before and after defibrillatory shock. The relationship between perishock pauses and survival to hospital discharge has been documented by the ACP Journal Club. Here is what their writers had to say…

“[The study] included out-of-hospital cardiac arrest patients…who suffered arrest between December 2005 and June 2007, presented with a shockable rhythm (ventricular fibrillation or pulseless ventricular tachycardia), and had cardiopulmonary resuscitation process data for at least 1 shock (n=815). …. In an analysis adjusted for Utstein predictors of survival, the odds of survival were significantly lower for patients with preshock pause ≥20 seconds… and perishock pause ≥40 seconds… compared with patients with preshock pause <10 seconds and perishock pause <20 seconds. Postshock pause was not independently associated with a significant change in the odds of survival. Log-linear modeling depicted a decrease in survival to hospital discharge of 18% and 14% for every 5-second increase in both preshock and perishock pause interval (up to 40 and 50 seconds, respectively), with no significant association noted with changes in the postshock pause interval.” 3

The article concludes that, “In patients with cardiac arrest presenting in a shockable rhythm, longer perishock and preshock pauses were independently associated with a decrease in survival to hospital discharge. The impact of preshock pause on survival suggests that refinement of automatic defibrillator software and paramedic education to minimize preshock pause delays may have a significant impact on survival.” 4

A poignant study eh?

In regards to manual defib, Paramedic blogger Chris Kaiser makes a great suggestion on how to reduce lagtime in compressions.

    “I timed my monitor as it charged up to 360 joules during a routine test. It took 8.3 seconds to go from 0 to 360j…Charge the defibrillator before every scheduled pause in compressions whether you need it or not. That way, when you pause to switch compressors at the 1 or 2 minute mark you can take a quick look at the monitor to make your “Shock or No-Shock” decision, shock immediately if needed, and get right back on the chest. There is little danger in doing this, even though I’ll admit that it takes a bit of getting used to. Don’t make your patient’s heart and brain wait those 8.3 seconds, pre-charge the defib.” 5

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A similar technique can be done with automatic defib as well. Providers should pause compressions for analysis, then get back on the chest during charge, stop again to shock. To avoid the sort of accident I’m sure you are mentally envisioning by now, make it a rule that the person doing compressions is the ONLY person to touch the defib.

Kaiser also suggests using a “Pre-Clear.”

“[A “pre-clear”] is where personnel who aren’t the one person providing chest compressions are trained to clear themselves from touching the patient 10 seconds before compressions cease during a scheduled pause. This way, once the compressions stop a shock can be delivered without waiting the 3 seconds it takes to say “I’m clear. You’re clear. Everybody’s clear” and push the shock button.” 7

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Kaiser (what a smart guy!) provides us with yet another idea to reduce perishock pauses:

Don’t Check for a Pulse or Look at the Monitor after a Shock– just start pumping right away. Don’t waste time checking for a pulse or looking at the monitor after a defibrillation shock is given. This is an unnecessary 5-10 seconds that could be spent moving the patient’s blood. Check the pulse if you see a rhythm change during your next scheduled pause in compressions but don’t increase your post-shock pause by looking or feeling. Resist the urge. Use Waveform Capnography (ETCO2) to see when the heart starts pumping again, a Return of Spontaneous Circulaton (ROSC) makes the ETCO2 spike up significantly. You’ll know it when you see it. Also, if you’re not sure if there is a pulse or not, assume there isn’t and start pumping.” 9 Nicely said Kaiser. You can check out more of his awesome ideas on his blog…

More CPR For Everyone!

The Department of Emergency Medicine at the University of Pennsylvania found that, “Despite the fact that quality of CPR has been shown to correlate with improved patient outcomes, conventional training methods are often insufficient in enabling healthcare providers to deliver high-quality resuscitation care.” They suggest that “[u]se of simulation methods during resuscitation training can increase subsequent resuscitation quality. Additionally, automated feedback during resuscitation has been shown to improve CPR performance. Focused debriefing after resuscitation can improve CPR quality and increase initial resuscitation success.” 10 We should all try getting down and dirty with Resusci Annie a little more often!


Now for something a little ridiculous…

Suspended Animation (or cryogenics)

So what if we aren’t likely to see this in the pre-hospital settings of our lifetime? I can totally picture its vibrant success on the emergency hovercrafts of my great-great grand-nieces. Plus it’s just a “cool” innovation to chat about.

The practical application study of suspended animation was recently initiated by the University of Pennsylvania. “As part of the study, any gunshot or stabbing victim who comes to the hospital ER in cardiac arrest will first get standard treatment: open-chest manual manipulation to restart the heart. (Closed-chest CPR doesn’t work in someone who has lost massive amounts of blood.) If manual manipulation fails, the study team will go into “preservation” mode. They will thread a large catheter directly into the patient’s aorta, the main artery of the heart, and infuse a cold saline solution… The solution is 50 degrees Fahrenheit, about the same as very cold tap water. As it circulates, it will chill first the heart and brain and then the rest of the body, until the patient’s body temperature is also 50 degrees. The cool down will take 15 to 20 minutes, at which point the patient will have no blood, no breath, no movement or any other outward sign of life.” 12 Told you it was cool! 😉

“By putting patients literally into a state of suspended animation…the surgeons intend to preserve brain functioning long enough to close wounds that would otherwise be fatal.” 13

I can’t wait to see what happens with the trials! Like I mentioned, it’s not very likely that any of us will actually be doing this procedure in the back of an ambulance…but it’s definitely a rock hard scientific fist pump!

Now for fun….here is a video of two simultaneous cardiac arrests in the ER with totally different outcomes…

Have a fist pumping day!












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