To cool or not to cool, that is the question.

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Since November 2013 the management of therapeutic hypothermia or what it is called now Target Temperature Management (TTM) has become a bit controversial. Previously, it was widely accepted to cool patients post cardiac arrest to  a temperature between 32-34 degrees for 24h to protect neurology and reduce the reperfusion injury. I was suggested that this temperature should be achieved as soon as it was practically possible with minimum side effects that could easily be managed under Intensive Care conditions. Obvious medical devices companies produced a number of expensive products to cope with the demand of this recommendations. Hospitals invested heavily in the purchase of cooling devices which could range from expensive ice packs to all singing all dancing liquid coolant devices. Also a cheaper option gained strength which was the infusion of cool normal saline from the fridge which shown to produce the desired effect. On November 2013 and just after the last European Resuscitation Council conference in Krakow, where we told “cooling just do it”, two articles hit the resuscitation front pages suggesting that TTM was not all as good as we though. Kim F. et al (2013) compared the induction of therapeutic hypothermia with 2L of normal saline after Return of Spontaneous Circulation (ROSC) in out of hospital cardiac arrest compared with those whom TTM was delayed until the arrival to hospital. The conclusion was survival rates did nor differ from these groups but pulmonary oedema and re arrest was more frequent on those cooled with this method, (there it goes our cheap option). The second study is even more revealing. Nielsen N. et all (2013) did not find any significant different on survival and neurological outcomes when comparing cooling between 33 and 36 degrees post cardiac arrest. One could possibly think that this is good news, 36 degrees is easily achievable, no need for risky rewarming face after TTM and no more expensive cooling systems to be purchased. However during the last few years it has been the general feeling that the 33 degrees has been successful, professionals from critical care services have been sharing stories of wonder recoveries after prolong down times after TTM. Yes it is true that electrolytes seems to derange more with this method but this easily corrected. It is true that we have to continue expending on the TTM management, but we have already done most of the investment. The obvious explanation could be that as soon as you avoid hypothermia post cardiac arrest the temperature is not that important. The other question is, do we have enough evidence to discard the original TTM? I will encourage the Resuscitation Council UK to use the data collected on the National Cardiac Arrest Audit (NCAA) to give us some direction. Long story short and without getting too deep into things we are still cooling at 33 degrees awaiting for some final statement to standardise treatment.


About the Author:

Resuscitation Officer, with a Nursing background and experience in emergency services.

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