Circadian variation on oxygen consumption in preterm infants.
OBJECTIVE
We investigated the diurnal variation in oxygen consumption to determine the optimal time periods of calorimetry in preterm infants.


METHODS
Oxygen consumption (VO(2)) was measured continuously for 24 h using indirect calorimetry. Twenty-two premature infants with gestational age of 27-31 (31+/-1.7) weeks were enrolled in the study. Heart rate, respiratory rate, oxygen saturation, skin and rectal temperature and physical activity were monitored continuously.


RESULTS
The averaged values of VO(2) showed a significant pattern (P<0.0001) of circadian rhythm with a peak in the afternoon and a nadir during the night with significantly differences between the mean VO(2) values. A circadian variation of VO(2) was found in more than 80% of preterm infants and was unrelated to gestational age, physical activity or environmental stress. The infants spent 90.4% of their time sleeping.


CONCLUSIONS
These findings indicate the possible existence of an endogenous circadian rhythm of VO(2) in preterm infants beginning shortly after birth. Day-night variations of VO(2) should be considered when VO(2) values are extrapolated from short measurement periods to prevent overestimation of values.
Bauer
Jacqueline
J
Department of Pediatrics, University Hospital of Muenster, Muenster, Germany. Jacqueline.Bauer@ukmuenster.de
Janecke
Andreas
A
Gerss
Joachim
J
Masjosthusmann
Katja
K
Werner
Claudius
C
Hoffmann
Georg
G
D002153:Calorimetry, Indirect; D002940:Circadian Rhythm; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000378:metabolism*; D010101:Oxygen Consumption