Prehospital Therapeutic Hypothermia- Suspended

This past week our Regional Medical Advisory Committee voted unanimously to suspend our prehospital therapeutic hypothermia guidelines in light of two recent studies.

The first, Effect of prehospital induction of mild hypothermia on survival and neurological status among adults with cardiac arrest: a randomized clinical trial, published in the January 2014 Journal of the American Medical Association, showed that while there was no difference in neurologically intact survival between those patients who were cooled prehospitally and those who were cooled in the hospital, those who were cooled prehospitally were more likely to rearrest and more likely to suffer side effects such as pulmonary edema.

The second study, Targeted Temperature Management at 33 degrees C versus 36 degrees C, published in the December 2013 New England Journal of Medicine, showed that there was no difference in survival between those patients who were cooled to 33 degrees Centigrade and those who were kept normothermic at 36 C.

It is now speculated that it was not necessarily cooling patients that was leading to improvements in survival, but keeping them from getting a fever that is likely the reason for better outcomes.

We have been cooling patients in the field in our area for about five years, but we have lacked any real ability to track our resuscitation rates, much less factor in hypothermia. Some services have been doing it, others partially, others not at all. When i was in the suburban contract town, we carried chilled saline in a cooler. In the city, we have been making do with ice packs and Versed if the BP is okay. In place of ice packs, I have often raided refrigerators for frozen vegetables. I don’t know if we saved any lives or not. Many of our area services and hospitals are joining the CARES registry so hopefully we will be better able to track our cardiac arrest outcomes in the future.

Bottom line for us. Cooling may not be all it has been cracked up to be. The evidence has yet to show a benefit to starting cooling in the field versus waiting to start it in the hospital. And while there is no evidence of benefit to starting cooling prehospitally, there is now evidence of harm. Thus, with that evidence of harm, we are suspending the procedure until there is good evidence of benefit.

I would like to say that we apply this approach to every medication or intervention that we use. We don’t, but we are making strides. Many are aware that there is no evidence that epinephrine improves functional neurological outcomes in cardiac arrest. And that the preponderance of the evidence suggests it may actually cause harm. Given its strong foothold in ACLS, we were unprepared to act to banish epinephrine, but we did vote to alter our epinephrine dosing during cardiac arrest from 1 mg every 3-5 minutes, to 1 mg every 5 minutes.


  • wwohl says:

    I didn’t notice in your article where your from. I think many readers are evaluating this information in different ways. While I agree that many organizations could likely get away with waiting until we hit the ED door, those that have 30+ minute transport times from the ED may not feel the same.

    Theres so many factors to consider when evaluating the efficacy of something like this. When we look at outcomes, we have to remember that a lot happens after we hand off to the ED staff. Very frequently, hypothermia therapy falls low on the priority scale for the ED staff. Even if we cool them, do they stay cool?

    Lets think about how EMS cools these patients too. When we consider the risk for pulmonary edema, we have to remember that our primary method is to bolus these patients with 2L + of chilled cystalloids. Also remember, this patient that we are overvolumizing has a stunned heart and is likely in some degree of cardiogenic shock or soon will be once the eli wears off.

    Id love to see your research and data and Id love to see what CARES has come up with. But there is a lot of documented evidence of the benefits to hypothermia therapy and I’m hard pressed to pull it from EMS completely when Ive seen substandard performance by ED to staff to implement it. What we need to consider is how to fix the risks of pulmonary edema by cooling the patients without massive fluid infusions. As far as an increased likelihood to arrest, well how to we measure that against the non cooled patients?

    New ACLS guidelines and mechanical CPR devices are rewarding more resuscitations than ever. But this growth in resuscitations are in the regions with extended downtimes who are likely acidotic and very likely to rearrest anyways..

    • medicscribe says:

      Thanks for the thoughtful comments.

      The evidence seems to be saying that the reason patients may be doing better is not because EMS is starting the cooling or even that the patients are getting cooled later in the hospital, but that the patients are being prevented from getting post arrest fever in the ICU.

      With all the new emphasis on CPR and all the new gizmos and procedures, sometimes it is hard to tell what is making the difference. But so far, the only evidence (outside of individual service data) of what happens prehospitally that makes a difference in functional outcomes are good CPR and defibrillation. Advanced airways, ACLS drugs, CPR machines and now prehospital hypothermia seem not to matter at least in the major published studies. Whether or not it will turn out that prehospital hypothermia for patients from rural areas will be a better or worse thing remains to be seen. I read somewhere, and am not certain who said it, but I agree, that based on the evidence we have now, prehospital therapeutic hypothermia should be reserved for services participating in approved research studies, and not for routine use. I would love to see those studies done.

      Thanks again for the comments,


  • Gary Shoemaker says:

    What agency stopped the hypothermia?

  • Kevin Franklin says:

    Kevin Franklin Induced therapeutic hypothermia is like any other medication or treatment we do with patients, whether it is on an EMS unit, in an ED, ICU or a general med floor. The difference I have seen over the past 20 years I have been involved is that often a service or unit will decide to initiate treatment/drug x without either understanding it completely or doing all of the steps necessary for its safety/efficacy in a given population. ITH is in the same ballpark as there are a number of studies that have shown significant benefit from it, whether this was preventing hyperthemia itself or related to actual hypothermia. The key finding with almost all successful studies I have looked at up to this point is that the researchers and clinicians performed all of the steps involved. For ITH this includes evaluating a patient for the standard inclusion/exclusion criteria and determining first if the patient is stable enough for the procedure. Next, and an absolute must in any study, is to evaluate the core temperature of the potential patient to see where they are at. Frequently patient will already be hypothermic because of the nature of cardiac arrest and the resuscitation process. Cooling these patients further below 32C is a known factor in worsening outcomes. Next is the easy part, applying whatever successful cooling measure you have in place. There are many that work but the key with all of them is that you must cool the patient effectively, monitor and provide necessary intervention during the process and continue to care which includes of course treatment for cardiogenic shock if necessary (though if present initially this is a contraindication). You then have to have a system setup that continues what you have started since warm to cold to warm to cold wreaks havoc on the patients body systems and often will worsen outcomes. Finally you absolutely have to have a way to follow your patients and their outcomes so that you know what is happening and whether your treatments or beneficial or not. I say all this as I have been a paramedic for 20+ years, an ED and ICU nurse for a a decade and a flight nurse for the past 8 years. So I have real time clinical background. In addition I have numerous degrees and experience in research so understand the research component. To me, all of those whom perform ITH without following these steps are being no more responsible then when we drove everyone emergency status to the hospital, regardless of their condition. So please, don’t stop doing the right things for your patients but also stop doing things that you either dont’ understand completely or don’t have the right tools or follow through to perform safely. EMS is a professional level of care and we need to uphold to that. Thanks. Kevin

  • John says:

    I understand your concern. My problem is with the EMS study. If you look closely the EMS group was given a paralytic and the group not cooled was not.

    That in of itself throws a red flag because both groups were not treated the same way. Also, paralytics inherently cause hypotension, so I would deduct that re-arrest is going to be more common.

    I do agree that temperature is probably the goal and not having a fever, but this study just showed there was no benefit to cooling, but there was also no harm.

    Just some thoughts.

  • Bob Sullivan says:

    I am excited that this level of research is being applied to EMS protocols. However, while post-arrest cooling does not appear to be as effective as we first thought, I would like to see the results of the intra-arrest cooling trials before pulling it off the trucks. A higher rate of ROSC was found in one of abstracts in the last Prehospital Emergency Care for patients who were cooled during resuscitation. If there’s anything here, I imagine it would be difficult to put cooling back into protocols after removing it.

  • Duke Powell says:

    Just from my experience as an EMS provider at a Level I Trauma Center:

    The biggest weaknesses in these studies are the seemingly inability of the EMS provider to follow the proticol.

  • Larry McCarter says:

    This has been a very interesting thread on TH. I find it disappointing that agencies are pulling their prehospital TH protocols just yet. I believe there are many plausible reasons why it may not appear to work – some listed above – cooling below 32C, overloading the lungs, etc., and not necessarily the TH itself. The bottom line though is that 75% of our ROSC patients that we deliver to the hospital, die in the hospital. What do they die from? Brain injury. And most of that occurs AFTER ROSC (“reperfusion injury”). TH can stop most of these damaging effects if applied appropriately and EARLY.

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