The rapid-fire presentation on targeted temperature management at the AHA Resuscitation Science Symposium from four world-class clinicians and researchers was challenging to follow. The key takeaways may be limited by my capability to follow and grasp the content at the high-level at which it was presented.
ORLANDO, Fla. — Resuscitation scientists discussed the role of therapeutic hypothermia at the American Heart Association’s Scientific Sessions 2015.
Targeted temperature management (TTM), though no longer recommended for prehospital initiation in the 2015 AHA CPR guidelines, still has a role in post-cardiac arrest patient care. The AHA gave its highest recommendation for the use of targeted temperature management for all comatose ROSC patients in the range of 32 C to 36 C.
In the first half of the session the presenters, Maaret Castre’n, M.D., Ph.D., Helsinki University Hospital, and Jesper Kjaergaard, M.D., Ph.D., Copenhagen University Hospital, made arguments for a specific temperature target, 33 C or 36 C, and which is better. Dozens of articles, which compared patient outcomes after cooling to 33 C or 36 C, were rapidly cited by Castre’n and Kjaergaard.
Kjetil Sunde, Oslo University Hospital, the third presenter, discussed the importance of individualized care with an added emphasis on the effect of outcomes with many examples from animal studies. Sunde described how reperfusion injury occurs during post-cardiac arrest syndrome. Hypothermia inhibits or lowers the risk of those injuries and in the animal models mentioned the time to therapeutic hypothermia initiation is important.
Trauma surgeon Eilen Bulger, University of Washington, was the fourth presenter. Bulger discussed the applicability of TTM for isolated trauma, specifically traumatic brain injury, and multisystems trauma. For most trauma patients hypothermia is a significant clinical concern and complication to treatment. Inducing hypothermia may be an option, as part of a clinical bundle, for some types of trauma patients.
Memorable quotes on targeted temperature management
“What is clear is that in the TTM trial which compared two temperature targets, 33 C vs. 36 C, is that the only difference was the temperatures. There was very similar survival in both groups.”
- Jesper Kjaergaard
“What matters (for cardiac arrest survivors) is cognitive function and quality of life.”
- Kjetil Sunde
“Spontaneous hypothermia is associated with shock. Therapeutic hypothermia is controlled as part of a treatment bundle.”
- Eileen Bulger
Key takeaways on targeted temperature management
TTM is an important part of post-cardiac arrest care for comatose patients. Here are my five takeaways from the panel presentation.
1. 36 C or 33 C?
The efficacy for patients appears to be similar. Cooling was the hottest topic at the Resuscitation Science Symposium. Expect more research in the years ahead.
2. Temperature control
Once the patient is cooled in the hospital, maintenance within the targeted temperature range is important.
3. Prehospital cooling
For now, initiation of therapeutic hypothermia happens in the hospital. Like all areas of medicine, TTM is dynamic. The initiation of cooling — where and when — may change as more is known through research. Research on TTM depth of cooling, duration and rewarming is underway in several locations around the world.
4. Reperfusion injury
The severity or degree of reperfusion injury depends on the cardiac arrest cause, time from arrest to CPR, the quality of CPR, time to defib/ROSC and post-arrest hemodynamics. Because of this variability the post-arrest care needs to be individualized to the patient.
5. Therapeutic hypothermia for trauma patients
Application of therapeutic hypothermia for isolated and multisystems trauma patients has been studied. The initial studies on adult TBI have not shown a difference in functional outcomes and several studies were stopped early. A pediatric study found worse functional outcomes in cooled patients.
There is very little data on cooling patients with spinal cord injury. More research is needed on the effect of local or systemic cooling.
Animal studies support rapid induction of deep hypothermia following traumatic cardiac arrest.
Final thought on TTM
There is value for EMS providers to know and understand, at least on some level, the interventions that are provided to cardiac arrest survivors by other health care providers. Many treatments that were once only in the domain of physicians — closed chest cardiac massage and defibrillation — are now expected to be performed rapidly and capably — hands-only CPR and AED use — by laypersons.
