Respiratory and metabolic ultradian (40 min<period<6h) variations in normal premature infants periodically fed through a gastric tube.

: Oxygen consumption (VO2) and carbon dioxide emission (VCO2) have been continuously recorded for 24 consecutive hours in 7 premature infants with a range of gestational age of 29-31 weeks at birth, and placed in incubators within a thermal neutral limit. These infants, submitted to continuous light, were fed every 3-4h through a gastric tube which was left in their stomachs throughout the whole experiment. Variance and spectral analyses performed on VCO2 values sampled on the recordings every 10 min showed ultradian variations, in the 40 min-6 h period range, which represent 20 and even 40% of the mean level. Moreover 5 out of the 7 premature infants show ultradian VCO2, VO2 and respiratory quotient rhythms related to feeding frequency.