title: Ventilatory response to a hyperoxic test is related to the frequency of short apneic episodes in late preterm neonates.
abstract: Chemoreception is frequently involved in the processes underlying apnea in premature infants. Apnea could result from a decrease in carotid body effectiveness. However, increased carotid body activity could also initiate apnea through hypocapnia following hyperventilation when the receptors are stimulated. The aim of this study was to analyze the relationship between carotid body effectiveness and short apneic episodes in older preterm neonates. Carotid body effectiveness was assessed at thermoneutrality in 36 premature neonates (2.07 +/- 0.26 kg) by performing a 30-s hyperoxic test during sleep, the oxygen inhalation involving a ventilation decrease. Blood O(2) saturation (Sp(o2)) and ventilatory parameters were monitored before and during the hyperoxic test. Short episodes of apnea (frequency and mean duration) were recorded during the morning's 3-h interfeeding interval. Pretest Sp(o2) was not related to any of the measured respiratory parameters. A higher frequency of short apneic episodes was linked to a greater ventilation decrease in response to the hyperoxic test (rho = -0.32; p = 0.01). Increased carotid body response is correlated with greater apneic episodes frequency, even in the absence of concomitant oxygen desaturation. Fetal or early postnatal hypoxemia could have increased peripheral chemoreceptor activity, which could initiate a "overshoot/undershoot" situation, which in turn could induce a critical P(o2)/P(co2) combination and apnea.
authors.affiliation: Dysrégulations Métaboliques Acquises et Génétiques (EA3901), Medical Faculty, University of Picardy, 80036 Amiens, France. virginie.cardot@etud.u-picardie.fr
authors.forename: Virginie
authors.initials: V
authors.lastname: Cardot
authors.forename: Karen
authors.initials: K
authors.lastname: Chardon
authors.forename: Pierre
authors.initials: P
authors.lastname: Tourneux
authors.forename: Sandrine
authors.initials: S
authors.lastname: Micallef
authors.forename: Erwan
authors.initials: E
authors.lastname: Stéphan
authors.forename: André
authors.initials: A
authors.lastname: Léké
authors.forename: Véronique
authors.initials: V
authors.lastname: Bach
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Libert
authors.forename: Frédéric
authors.initials: F
authors.lastname: Telliez
mesh_terms: D002344:Carotid Body / Q000378:metabolism / Q000503:physiopathology*; D025461:Feedback, Physiological; D005865:Gestational Age; D006801:Humans; D018496:Hyperoxia / Q000097:blood / Q000503:physiopathology*; D007231:Infant, Newborn; D007234:Infant, Premature; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D012123:Pulmonary Ventilation; D012129:Respiratory Function Tests; D012890:Sleep; D012891:Sleep Apnea Syndromes / Q000097:blood / Q000503:physiopathology*; D013997:Time Factors