Influence of thermal drive on central sleep apnea in the preterm neonate.
BACKGROUND
The incidence of apnea in neonates depends on a number of factors, including sleep state and thermoregulation.


OBJECTIVE
To assess the role of thermal drive (body heat loss [BHL]) in the mechanisms underlying short episodes of central apnea during active and quiet sleep in neonates.


METHODS
Twenty-two neonates (postconceptional age: 36.3 +/- 0.9 weeks) were exposed at thermoneutral (incubator temperature: 32.5 degrees C), warm (34.2 degrees C), and cool (30.4 degrees C) conditions during 3 consecutive morning naps. Oxygen consumption (VO2), skin and rectal temperatures, and central apnea were scored during active sleep and quiet sleep. The thermal drive was expressed as BHL calculated using indirect partitional calorimetry.


RESULTS
As expected, apnea occurred more frequently in active sleep than in quiet sleep (P < 0.001). The frequency of apnea in active sleep was higher in the warm condition (P < 0.05). In contrast, apnea episodes were less frequent (P < 0.05) and shorter (P < 0.05) for cool exposure, during which VO2 and rectal temperature increased. The frequency (P < 0.001, r2 = 0.31), mean (P < 0.05, r2 = 0.06), and maximum (P < 0.001, r2 = 0.19) durations of apnea were correlated with the BHL: the greater the BHL (body cooling), the less frequent and the shorter the apnea episodes. In contrast, no relationship between apnea and mean skin or rectal temperature was observed.


CONCLUSIONS
Apneic events were more closely related to BHL than to body temperatures. In cool exposure, the decreases in the duration and frequency of apneic episodes suggest that these events depend on the metabolic drive (which is proportional to energy expenditure).
Tourneux
Pierre
P
PériTox (EA 3901-UM INERIS), Faculty of Medicine, Jules Verne University of Picardy, Amiens, France. tourneux.pierre@chu-amiens.fr
Cardot
Virginie
V
Museux
Nathanaëlle
N
Chardon
Karen
K
Léké
André
A
Telliez
Frédéric
F
Libert
Jean-Pierre
JP
Bach
Véronique
V
D001831:Body Temperature; D001833:Body Temperature Regulation / Q000502:physiology; D005260:Female; D006801:Humans; D007186:Incubators, Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D012890:Sleep / Q000502:physiology; D020182:Sleep Apnea, Central / Q000628:therapy*