Which patients benefit from therapeutic hypothermia?
| Response from Scott D. Weingart, MD, RDMS
Assistant Professor; Director of Emergency Department Critical Care, Mount Sinai School of Medicine, New York, NY
Any patient with nontraumatic post-cardiac arrest who is sent to an intensive care unit would benefit from therapeutic hypothermia. This alludes to the 1 absolute exclusion criterion for therapeutic hypothermia: poor baseline status/advanced directives. Inclusion criteria can also be simplified: any patient not following commands (Glasgow Coma Scale motor < 6 ) is eligible. Although the absolute benefit and evidentiary basis are greatest for out of hospital (OOH) ventricular fibrillation, evidence is accumulating for all OOH rhythms.Preliminary data from the NYC Project Hypothermia initiative also support cooling all OOH rhythms (Freese J. Personal communication. Project Hypothermia Update. Greater NY Hospital Association. October 1, 2009.).Although no published data exist on arrests in the emergency department, small series support in-hospital cooling.A patient who is sent to a critical care setting should be given the best possible neurologic outcome.
When first starting a therapeutic hypothermia program, inexperienced practitioners may balk at inducing hypothermia in patients with hypotension or discontinue the process due to decompensation. However, rarely is hypothermia to blame for any deleterious changes in the patient's condition. The more likely culprits are the systemic inflammatory response syndrome (SIRS)-like hemodynamic changes of post-cardiac arrest syndrome, poor cardiac output from myocardial stunning, or the pathology that caused the original arrest.
If all rhythms brought in from the field are cooled, screening becomes relatively simple. The only challenge would be delineating what is poor baseline status. This question touches on the areas of ethics, palliative care, and the economics of our health system. A full discussion of these ethics would require an entire manuscript, but the first thing to consider is that therapeutic hypothermia will not make the patient's neurologic or daily living status any better than it was before the arrest. As a rule, if you would not have admitted the patient to an intensive care unit before the enrollment in a hypothermia protocol, then the patient should not receive the therapy. One rule of thumb is that if the patient is older than 75 years , has dementia, and cannot maintain activities of daily living, I do not initiate hypothermia.
At this point, therapies that show actual benefit in peri-arrest can be reduced to good chest compressions, rapid defibrillation, therapeutic hypothermia, and good supportive care in the post-arrest period. Any emergency department resuscitation should concentrate on these 4 elements. Although providing therapeutic hypothermia may seem daunting, expensive, and labor intensive, it is actually the provision of adequate supportive care that requires most of the resources. If good post-arrest critical care is provided in the emergency department, adding therapeutic hypothermia is relatively easy. With or without hypothermia, these patients require low-ratio nursing, constant physician assessment, invasive monitoring, hemodynamic support, and aggressive interventions. If a center cannot provide therapeutic hypothermia, it may be worth asking whether that center is the optimal destination for a patient after cardiac arrest.
Medscape Emergency Medicine © 2009 Medscape, LLC
Cite this: Scott D. Weingart. Therapeutic Hypothermia - Medscape - Dec 18, 2009.