Human brain temperature during anesthesia for intracranial operations

The intraventricular and rectal temperatures were registered in nine patients subjected to major surgery of the brain. Copper-constantan thermocouples were introduced into the lumen of an intraventricular catheter also used for perioperative monitoring of intracranial pressure. During anesthesia, the intraventricular temperature was higher than rectal temperature, the mean difference being 0.30 +/- 0.24 degrees C. No significant changes in intraventricular temperature were seen during different stages of the operations. It is concluded that during routine anesthesia rectal temperature can be relied on for a reasonable estimation of human brain temperature. It should be observed, however, that in the postoperative period, both rectal and intraventricular temperature rose considerably. In three patients, the intraventricular temperature rose as much as 2.5-4 degrees C, thus increasing the temperature gradient between rectum and brain. The relevance of these findings are discussed.