Therapeutic Hypothermia

Mild hypothermia may suppress chemical reactions associated with reperfusion injury post- arrest. Therapeutic hypothermia was in vogue up until recent years where more recent evidence has shown prevention of hyperpyrexia to be associated with better outcomes.

Guidelines have shifted towards supporting targeted temperature management rather than therapeutic hypothermia. TTM aims to maintain temperature between 32-36 degrees Celsius. TTM should be initiated immediately post-ROSC in all patients who remain comatose, regardless of initial rhythm. These measures should be maintained for at least 24 hours.

It is likely that it is the prevention of pyrexia, rather than cooling per se, which leads to outcome differences in the post-arrest patient.

Local preference and guidelines should be followed for exact temperature target but in all cases, pyrexia should be avoided.

Pyrexia must be avoided post-cardiac arrest. It is common in the first 48 hours and the risk of a poor neurological outcome increases with each degree rise over 37^oC. [4]

The Advanced Life Support Task Force of the International Liaison Committee on Resuscitation (ILCOR) have recommended that the term Targeted Temperature Management (TTM) replace the historic term Therapeutic Hypothermia.

ILCOR recommend:

1. Maintain a constant, target temperature between 32-36 degrees centrigrade for those patients in whom temperature control is used
2. TTM is recommended for adults after OHCA with an initial shockable rhythm who remain unresponsive after ROSC
3. TTM is suggested for adults after OHCA with an initial non shockable rhythm who remain unresponsive after ROSC
4. TTM is suggested for adults after IHCA with any initial rhythm who remain unresponsive after ROSC
5. If TTM is used, it is suggested that the duration is at least 24 hours

Most ITU clinicians in the UK now use 36 degrees centigrade as the TTM post cardiac arrest.