Assessment and prevention of shivering in patients with severe cerebral injury. A pilot study

Low body temperature is induced by surface cooling to reduce metabolic demands in patients with severe cerebral injury. Shivering, which increases energy expenditure, is a common effect of surface cooling. The aim of this pilot study was to investigate whether increased gradient between the set point and peripheral temperature is related to shivering and whether modifying the loss of body heat during surface cooling decreases the frequency of shivering. Seven cerebrally injured patients at a neurosurgical ICU were studied. Shivering, surface cooling and the temperature gradient measured as the tympanic and the tip toe temperatures were registered every 30 min. Shivering was assessed at three levels: no shivering, mild shivering and severe shivering. In four patients the arms and legs were covered with a cotton cloth for part of the observation time to modify the rate of heat loss. The temperature measurements were repeated in each patient between 13 and 42 times. Four patients out of seven shivered. There was a significant association between increased temperature gradient and shivering (P < 0.01). Modifying the rate of heat loss decreased the temperature gradient (P < 0.001). By simultaneously measuring the tympanic and tip toe temperatures it may be possible to detect shivering earlier and decrease its frequency by modifying the loss of body heat during surface cooling.