Abstract
Although current practice guidelines do recommend sedation/analgesia (with or without paralytics to prevent shivering), there is no evidence that one method is superior to another. Chamorro et al. (2010) published a systematic review that describes the variability in choices of drugs and dosages utilized in 68 intensive care units in a variety of countries. Midazolam and propofol were the most commonly used sedatives, and fentanyl and morphine were the most popular analgesics.
Polderman and Herold (2009) state in their review article that the available evidence supports the use of sedation and analgesia in the successful application of TH. They suggest as well that shivering can be controlled with sedation, anesthetics, and opiates in addition to other drugs and counter-rewarming methods. This review also includes a description of earlier animal data showing no neuroprotective effect if TH was carried out without sedation/analgesia, possibly due to an aggravated stress response. No human data are available to support this.
Many standard order sets supporting TH protocols call for the sedation/analgesic most commonly used and available in that particular institution. For example, one protocol advocates the use of both a sedative and analgesic: fentanyl and lorazepam are popular combinations, and propofol might be used in place of lorazepam. If shivering is controlled with the methods described above, one could evaluate the patient's discomfort with the Richmond agitation-sedation scale or the hospital's preferred pain/sedation assessment tool.
If, however, paralytics are employed to control shivering, some institutions find the bispectral index (BIS) device very useful, targeting a BIS value of 40–60 to monitor and guide sedation.
From a practical standpoint, most caregivers would be uncomfortable using a TH protocol in which the possibility of a patient's discomfort is not addressed. And while it is true that the administration of sedation/analgesia may prolong the “waking up” phase, we want to provide the absolute best care to the patient, minimizing the adverse effects of this promising therapy. Continued exploration and validation of new sedation protocols will provide the evidence that will allow us to provide that best practice.