Chillin’
As neurologists, we are often called upon to give an opinion regarding the prognosis of patients
who have suffered a cardiac arrest. Fortunately, the AAN has an excellent position paper to help guide
such evaluations. i Our opinions are requested regarding the possibility of withdrawing of medical care
if it would be considered futile, but how often are we asked to provide management input into those
patients who have suffered from a cardiopulmonary arrest? A recent review of the topic of therapeutic
hypothermia published in the New England Journal of Medicineii piqued my interest regarding how
often and by which service this modality was being employed in clinical practice.
The article reports that there are about 400,000 out of hospital cardiac arrests per year in the
U.S. Resuscitation is attempted on about 100,000 of these and about 40,000 patients survive to be
admitted to the hospital. The effects of such global ischemia are now termed the “post-cardiac arrest
syndrome. As you would expect, this carries a poor prognosis with only about a third of these surviving
to hospital discharge. The most devastating manifestations of this syndrome are neurologic, so any
means available to mitigate CNS damage may have great potential benefits.
Two trials published in 2002 provided convincing evidence of the efficacy of targeted
temperature management. An Australian trial with 77 patients showed a 49% survival with favorable
neurological outcome in the treated group compared to only 26% of the normothermia group. A
European trial involving 275 patients showed a difference of 55% vs. 39% of favorable neurological
recovery in the treated group.
The treatment protocol calls for rapid core body temperature cooling- to be done within ten
hours of a pulseless cardiac arrest in patients who are hemodynamically stable after resuscitation but
remain comatose. Cooling methods may vary, but frequently entail such low technology modalities as
the use of ice packs or cooling pads. Another means of cooling uses the infusion of cold (4 degrees C)
Lactated Ringers – 30cc/Kg (usually about 2 liters). Patients must be intubated and provided with
sedation, analgesia and be paralyzed to prevent shivering. The article has a protocol consisting of :
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Midazolam 0.15 mg per kilogram per hour
Fentanyl 2.5 microgram per kilogram bolus and 2.5 microgram per kilogram hourly infusion
Rocuronium (paralytic) at 0.5 mg per kilogram bolus and 0.5 mg per kilogram per hour after
The desired temperature is between 32 and 34 and ideally should be maintained for 24 hours.
Rewarming should be done slowly- at about 0.3 to 0.5 degrees C per hour.
The AAN Guidelines for predicting survival after cardiac arrest may no longer apply after the
hypothermia protocol has been completed. Given the dismal prognosis after out of hospital (or even in
hospital) cardiac arrest, it would seem like routinely using targeted temperature management is
preferable. How often is this type of protocol used in your facility? Who decides?
i
Widjicks EFM, Hijdra A, Young GB et al. Practice parameter:predicition of outcome in comatose survivors after
cardiopulmaonary resucscitation (an evidence-based review): report of the Quality Standards Subcommittee of the
American Academy of Neurology. Neurology 2006; 67: 203-210
ii
Holzer,M. Targeted Temperature Management for Comatose Survivors of Cardiac Arrest. NEJM 2010; 363:12561264