BRAIN TEMPERATURE DISCRIMINATES BETWEEN NEONATES WITH DAMAGED, HYPOPERFUSED, AND NORMAL BRAINS

Brain temperature depends on the balance of cerebral heat production and heat loss via cerebral circulation and head surface. We investigated whether brain temperature and heat loss via the head surface differed in neonates with abnormal cerebral metabolism or circulation. We measured the core temperature of the head noninvasively by the zero-gradient method, skin temperature of the head, the heat flux from the head, and esophageal and operative environmental temperature in seven healthy neonates, seven neonates with cerebral damage, and two neonates with cerebral hypoperfusion caused by an incurable congenital heart disease. Cerebral blood flow velocity in the anterior cerebral artery and systemic blood pressure were also measured. Brain temperature profile was measured in two premature infants with external ventricular drainage. Core temperature of the head, considered to represent brain temperature, was up to 1.5-degrees-C higher in infants with cerebral hypoperfusion than in normal neonates. The core temperature of the head was higher than the esophageal temperature in all except two infants with the most severe cerebral damage. The difference between core temperature of the head and esophageal temperature was 0.72 +/- 0.12-degrees-C in normal neonates, 0.16 +/- 0.4-degrees-C in infants with cerebral damage, and ranged from 0.9 to 1.2-degrees-C in infants with cerebral hypoperfusion. The relationship of core of the head to esophageal temperature discriminated between all 16 newborn infants according to their brain pathologic condition, except one infant with a mild ischemic-hypoxic encephalopathy. In conclusion, brain temperature depends on cerebral perfusion and level of brain injury. The relationship of brain to esophageal temperature could be used to monitor cerebral perfusion and metabolism of patients at low cost.