Brain Temperature Discriminates Between Neonates with Damaged, Hypoperfused, and Normal Brains

Abstract

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 degree 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 degree C in normal neonates, 0.16 +/- 0.4 degree C in infants with cerebral damage, and ranged from 0.9 to 1.2 degree 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved reproducibility of MRS regional brain thermometry by ‘amplitude‐weighted combination’

“…Infant studies have reported T rec $ 0.58C greater than abdominal skin temperature (35) and head core temperature approximately 0.78C greater than oesophageal temperature (36). In our study, infant abdominal skin temperature was 36.5-37.58C, suggesting a head core temperature approximately 1.08C higher and compatible with T AWC .…”

Methodological investigation of measuring nasopharyngeal temperature as noninvasive brain temperature analogue in the neonate

“…In small animals the temperature beneath the temporalis muscle has been found to closely reflect the brain core temperature. In two human newborns with external drainage the temperature gradient between the intraventricular space and the head skin has been found to differ less than 1.5 C [5]. Consequently it seems justified to use epidural temperature as a measure of changes in brain temperature for comparing various other body temperatures.…”

“…itored indirectly by means of nasopharyngeal temperature (T nasoph ) differs from other body core temperatures with considerable differences in the presence of various diseases [4,5] and induced hypothermia [6,7]. Apart from highly sophisticated techniques such as magnetic resonance spectroscopy [8] and microwave thermography [9], temperature measurements at the tympanic membrane [10], meatus accusticus [11], insulated temple [12], forehead [5,13], nasopharynx [14], esophagus (T esoph ), bladder, and rectum (T rectum ) [15] have been proposed for the noninvasive monitoring of a temperature analogue of the brain.…”

“…Apart from highly sophisticated techniques such as magnetic resonance spectroscopy [8] and microwave thermography [9], temperature measurements at the tympanic membrane [10], meatus accusticus [11], insulated temple [12], forehead [5,13], nasopharynx [14], esophagus (T esoph ), bladder, and rectum (T rectum ) [15] have been proposed for the noninvasive monitoring of a temperature analogue of the brain. Most of the existing data are from studies in adult patients and are partly conflicting: Jugular bulb and esophageal and rectal temperatures are only poorly related to invasively measured brain temperature in adult neurointensive care patients [4,16,17].…”

Innate Hypothermia after Hypoxic Ischaemic Delivery

“…A full characterisation of the phenomenon would require the use of calorimetry to quantify the heat transfer to the environment. The greatest challenge is to identify a relationship between thermal maladaptation and encephalopathy following HI delivery [37]. …”