Temperature differences during sleep between fullterm and preterm neonates at matched post-conceptional ages.

OBJECTIVE

Altered physiologic behaviors during sleep have been described for healthy preterm neonates at post-conceptional fullterm ages. These differences may reflect brain dysmaturity as a result of conditions of prematurity. The present study examines if differences in state-specific temperature changes exist in a healthy preterm cohort as another expression of brain dysmaturity.

METHODS

Rectal and skin temperatures during sleep state transitions are reported in 59 asymptomatic post-conceptional age term infants, comparing 25 full term and 34 preterm infants. Three-hour 24-channel electroencephalogram (EEG)-sleep studies were recorded for each child. One of 4 sleep states were assigned for each of 7339 min, based on both cerebral and non-cerebral measures. For each study, average rectal and skin temperatures for each sleep state were calculated. Repeated measures MANOVA were performed using 4 explanatory variables, average skin and rectal temperatures and variance of rectal and skin temperatures, comparing preterm/fullterm status and 4 sleep states.

RESULTS

Rectal temperature differences between neonatal cohorts during specific sleep states were noted: F=8.58, P<0.0001. Significant differences were noted for both average and variance of rectal temperatures during all 4 sleep states with higher temperatures in the preterm group. For all neonates, both skin and rectal temperature differences were also noted among sleep states (F=4.22, P<0.0004). Differences were specifically noted between two specific EEG segments, mixed frequency active sleep and tracé alternant quiet sleep (P<0.0004).

CONCLUSIONS

In summary, significant differences in temperatures were noted across sleep state transitions for two neonatal cohorts, with higher average rectal temperatures in the preterm cohort. These findings highlight an altered measure of brain function during sleep in preterm infants affecting temperature regulation. This altered physiologic behavior reflects adaptation of the infant's brain function to conditions of prematurity which may contribute to vulnerabilities at older ages.