Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

What Can EMS Expect From 2014? #2 Prehospital Therapeutic Hypothermia


 

It was the sexy new EMS treatment.

The use of fluids for prehospital therapeutic hypothermia was rushed into protocols.

Now that we have evidence, was a mistake?

Some of us are now trying to defend the rush to treat before evidence.
 

CONCLUSIONS:
In unconscious survivors of out-of-hospital cardiac arrest of presumed cardiac cause, hypothermia at a targeted temperature of 33°C did not confer a benefit as compared with a targeted temperature of 36°C.
[1]

 

Cooler was not better in this study.

Patients were cooler, but outcomes were slightly worse for the cooler patients.

The difference was not statistically significant.
 

Conclusion and Relevance Although use of prehospital cooling reduced core temperature by hospital arrival and reduced the time to reach a temperature of 34°C, it did not improve survival or neurological status among patients resuscitated from prehospital VF or those without VF.[2]

 

Patients were cooler, but outcomes were again slightly worse for the cooled patients.

The difference was not statistically significant, but all measures trended toward worse with prehospital cooling.
 

There was one study that did trend toward improved outcomes for asystole/PEA (Pulseless Electrical Activity) patients, but the results were not statistically significant.
 

In the patients with a cardiac cause of the arrest, 8 of 47 patients (17%) who received pre-hospital cooling had a favorable outcome at hospital discharge compared with 3 of 43 (7%) in the hospital cooled group (p = .146).[3]

 

Maybe there will be some benefit shown for asystole/PEA patients with a larger study, but this is the most positive evidence and it is not statistically significant –

In other words, there is no evidence of benefit and no reason to use this treatment outside of a controlled trial.
 


 

CONCLUSIONS:
In adults who have been resuscitated from out-of-hospital cardiac arrest with an initial cardiac rhythm of ventricular fibrillation, paramedic cooling with a rapid infusion of large-volume, ice-cold intravenous fluid decreased core temperature at hospital arrival but was not shown to improve outcome at hospital discharge compared with cooling commenced in the hospital.
[4]

 

Patients were cooler, but once again outcomes were slightly worse for the cooled patients.

The difference was not statistically significant, but all measures trended toward worse with prehospital cooling.

There is a free editorial that is important to read accompanying this paper. There are possible explanations for the consistent failure to improve outcomes.
 

Swine studies show that ice-cold saline delivered during cardiac arrest reduces coronary perfusion pressure (CPP).4,5 Yannopolous et al4 found that iced saline reduced CPP during CPR from 24 mm Hg to only 4 mm Hg, an alarmingly low value that makes survival unlikely.[5]

 

We rushed to implement protocols to give fluids for prehospital therapeutic hypothermia.

Because of our failure to wait for evidence, we need to get rid of these protocols.

When will we learn to wait for evidence?

When will we put our patients’ health above our need to use the new and untested?

Footnotes:

[1] Targeted temperature management at 33°C versus 36°C after cardiac arrest.
Nielsen N, Wetterslev J, Cronberg T, Erlinge D, Gasche Y, Hassager C, Horn J, Hovdenes J, Kjaergaard J, Kuiper M, Pellis T, Stammet P, Wanscher M, Wise MP, Åneman A, Al-Subaie N, Boesgaard S, Bro-Jeppesen J, Brunetti I, Bugge JF, Hingston CD, Juffermans NP, Koopmans M, Køber L, Langørgen J, Lilja G, Møller JE, Rundgren M, Rylander C, Smid O, Werer C, Winkel P, Friberg H; TTM Trial Investigators.
N Engl J Med. 2013 Dec 5;369(23):2197-206. doi: 10.1056/NEJMoa1310519. Epub 2013 Nov 17.
PMID:24237006[PubMed – indexed for MEDLINE]

[2] Effect of Prehospital Induction of Mild Hypothermia on Survival and Neurological Status Among Adults With Cardiac Arrest: A Randomized Clinical Trial.
Kim F, Nichol G, Maynard C, Hallstrom A, Kudenchuk PJ, Rea T, Copass MK, Carlbom D, Deem S, Longstreth WT Jr, Olsufka M, Cobb LA.
JAMA. 2013 Nov 17. doi: 10.1001/jama.2013.282173. [Epub ahead of print]
PMID: 24240712 [PubMed – as supplied by publisher]

[3] Induction of prehospital therapeutic hypothermia after resuscitation from nonventricular fibrillation cardiac arrest*.
Bernard SA, Smith K, Cameron P, Masci K, Taylor DM, Cooper DJ, Kelly AM, Silvester W; Rapid Infusion of Cold Hartmanns Investigators.
Crit Care Med. 2012 Mar;40(3):747-53. doi: 10.1097/CCM.0b013e3182377038.
PMID: 22020244 [PubMed – indexed for MEDLINE]

[4] Induction of therapeutic hypothermia by paramedics after resuscitation from out-of-hospital ventricular fibrillation cardiac arrest: a randomized controlled trial.
Bernard SA, Smith K, Cameron P, Masci K, Taylor DM, Cooper DJ, Kelly AM, Silvester W; Rapid Infusion of Cold Hartmanns (RICH) Investigators.
Circulation. 2010 Aug 17;122(7):737-42. doi: 10.1161/CIRCULATIONAHA.109.906859. Epub 2010 Aug 2.
PMID: 20679551 [PubMed – indexed for MEDLINE]

Free Full Text from Circulation.

[5] Cooling heads and hearts versus cooling our heels.
Becker LB.
Circulation. 2010 Aug 17;122(7):679-81. doi: 10.1161/CIRCULATIONAHA.110.968222. Epub 2010 Aug 2. No abstract available.
PMID: 20679546 [PubMed – indexed for MEDLINE]

Free Full Text from Circulation.

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