The benefits of therapeutic hypothermia in a comatose pt after arrest?

[thatoneguyRN]

Hello all you critical care nursing peoples,

I had a patient try to go meet Jesus on me the other night. Witnessed cardiac arrest, we got him back within a few minutes, and they were following commands before I put them back under with some propofol as they was emergently re-intubated.

The charge nurse said he did not meet criteria for cooling as he we had a good neuro exam before he was sedated--he was following commands. I have done some research and found that there is good evidence that therapeutic hypothermia improves outcomes for pts with unwitnessed arrests, but not so much on witnessed and not a lot on the reasons why, and as the rest of my night was spent checking and re-checking labs, supplementing electrolytes like it was going out of style and generally being busy. I didn't get to ask.

So my question is do any of you have the reasons behind why we cool comatose post-arrest pts after return of ROSC? Is it to protect the brain/heart tissue by lowering metabolic/oxygen demand or is there some other cool (heh, heh) reason? Gracias in advance.

[Anna Flaxis, BSN, RN]

My understanding is that most of the data is from out of hospital arrests, and that in-hospital arrests are not well studied.

There are a lot of pathophysiological processes that occur as a result of the insult to the body of even just a few minutes of inadequate perfusion that therapeutic hypothermia is intended to address, but yes, the primary reason is improved neurological outcome.

[JSBSN]

We do therapeutic hypothermia quite a bit in our unit. We mostly do it on out of hospital WITNESSED arrests. Those that were unwittnessed have had little success because no one knows how long the patient was down before resuscitation efforts were started. We have also done therapeutic hypothermia on in-hospital arrest patients as well, but generally these patients are MORE sick (because they are already in the hospital of course) and again may not have quite as good outcomes. It works best on those with witnessed arrests because generally CPR is started earlier and there is a rough idea of how long they were down.

Our protocol is specifically for vtach/vfib arrest. The problem with trying to use it on a patient who has PEA is that PEA is usually caused by something else going on (sepsis, metabolic problems, kindey failure, shock, etc) that makes it more dangerous to cool them.

The REASON for cooling is that it slows down metabolism and preserves brain function. Nothing can be done about the initial hypoxic event, but the SECONDAY injury (reperfusion injury, free radical damage, edema) can be limited by cooling them.

We had a 29 year old patient who was down for approx 20 minutes WITHOUT CPR. We used our arctic sun machines and treated him with therapeutic hypothermia. He was even posturing for a day or so. He ended up going on CRRT and needed an oscilator for ARDS. He walked out of the hospital 3 weeks later completely neurologically intact!!! He's still doing great and back to work a couple months later.

[thatoneguyRN]

Interesting, and thanks. It does make sense that it would be for witnessed arrests and the piece about preventing reperfusion injury is fascinating. I will have to look into that.

Also part of why we didn't cool may have been that my patient along with following commands converted into PEA...oh joy, and then we got ROSC after the secondary temp pacer kicked in, with some help from epi and good old quality CPR. The temp/perm did not seem to be doing it. One sick patient, but I am encouraged by your story JSBSN, I hope this patient does equally as well.

[Anna Flaxis, BSN, RN]

The charge nurse said he did not meet criteria for cooling as he we had a good neuro exam before he was sedated--he was following commands. I have done some research and found that there is good evidence that therapeutic hypothermia improves outcomes for pts with unwitnessed arrests, but not so much on witnessed

Just re-read your post. Your charge nurse had a valid point that since the patient was not comatose following ROSC, that would disqualify him from therapeutic hypothermia (assuming his GCS was >8), at least I would think so. Also, the evidence showing improved outcomes is primarily on *witnessed* out of hospital VT/VF arrests. JSBSN is correct that PEA arrests do not have significantly improved outcomes with therapeutic hypothermia.

[thatoneguyRN]

I think I got my witnessed and unwitnessed wires crossed. The article I looked at was for witnessed arrests as you guys pointed out. It makes sense.

[Esme12, ASN, BSN, RN]

Interesting, and thanks. It does make sense that it would be for witnessed arrests and the piece about preventing reperfusion injury is fascinating. I will have to look into that.

Also part of why we didn't cool may have been that my patient along with following commands converted into PEA...oh joy, and then we got ROSC after the secondary temp pacer kicked in, with some help from epi and good old quality CPR. The temp/perm did not seem to be doing it. One sick patient, but I am encouraged by your story JSBSN, I hope this patient does equally as well.

Simply put they just weren't hypoxic long enough to fit criteria.

[StayLost, BSN, RN]

Therapeutic hypothermia is NOT recommended for patients who suffered an UNwitnessed arrest. This is because the length of down-time is important to determine if a patient is a candidate, simply because it's not effective after a certain amount of time.

The main way it works is by decreasing metabolic needs, decreases catecholamine release, and decreases apoptosis- brain cell suicide :)

[AwesomeManRN]

If he was following commands post arrest, he does not need hypothermia. Hypothermia is only indicated in pts who are unresponsive post arrest. The anoxic injury was not significant enough to have any benefit from hypothermia. Side note- recent study shows that hypothermia has no clinical improvement over preventing hyperthermia post arrest.