title: A method of assessing ventilatory responses to chemoreceptor stimulation in infants.
abstract: Various methods of assessing infant chemoreceptor responses have been reported in the literature. However, equipment dead space, trigeminal stimulation and inherent respiratory variability may have affected the results. A method is presented which attempts to reduce the effect of these factors and thereby isolate the chemoreceptor response. Inspiratory gas was delivered into a lightweight face mask with a pliable rim, minimal dead space and a connected pneumotachograph. Ventilatory data were computed breath by breath. Computer-controlled electromagnetic valves allowed instantaneous switching between air and different gas mixtures, repeated in a randomized sequence. In 18 healthy term neonates, the mask increased ventilation by 12% (95% confidence interval 6-18%), measured by calibrated strain-gauge bands. The effect on respiratory frequency and tidal volume differed significantly between sleep states. Neonates were challenged with short-lasting hyperoxia, mild hypoxia, rebreathing and mild hypercapnia. Coherent averaging of several ventilatory responses from each sleep state reduced the variability while maintaining a high time-resolution.
authors.affiliation: Institute of Physiology, University of Oslo, Norway. signe.sovik@basalmed.uio.no
authors.forename: S
authors.initials: S
authors.lastname: Søvik
authors.forename: M
authors.initials: M
authors.lastname: Eriksen
authors.forename: K
authors.initials: K
authors.lastname: Lossius
authors.forename: J
authors.initials: J
authors.lastname: Grøgaard
authors.forename: L
authors.initials: L
authors.lastname: Walløe
mesh_terms: D000704:Analysis of Variance; D002628:Chemoreceptor Cells / Q000502:physiology*; D004867:Equipment Design; D005740:Gases; D006801:Humans; D007231:Infant, Newborn; D010812:Physical Stimulation / Q000295:instrumentation; D012119:Respiration; D012134:Respiratory Protective Devices; D012895:Sleep, REM / Q000502:physiology; D013997:Time Factors; D014276:Trigeminal Nerve / Q000502:physiology*
chemical_list: D005740:Gases