title: Comparison of the hyperoxic test and the alternate breath test in infants.
abstract: Peripheral chemoreceptor function has been tested using either the hyperoxic test (HT), which decreases minute ventilation (V E) by causing physiologic chemodenervation, or the alternate breath test (ABT), which induces V E alternations by delivering rapid hypoxic stimuli through breath-by-breath alternations in fractional inspired O(2) between normoxia (0.21) and hypoxia (0.15). No previous studies have compared ventilatory responses to both tests in the same infants. We hypothesized that the V E decrease during HT would be significantly related to V E alternations during ABT. Eighteen infants (postnatal age 21 +/- 14 d) underwent two 30-s HTs and two ABTs (quiet sleep, face mask, and pneumotachograph; mass spectrometry measurement of inspired and expired O(2) and CO(2) fractions; and breath-by-breath analysis). The tests were done in random order. Decreases in V E and mean inspiratory flow (tidal volume over inspiratory time, VT/TI) during HTs were significantly correlated to their respective percentage coefficients of alternation during ABTs (r = 0.69 and 0.70, respectively, p < 0.01). Principal components analysis showed that the V E and VT/TI decreases during HTs were due chiefly to a fall in VT, whereas V E and VT/TI alternations were ascribable to alternations in both VT and TI. Intraindividual coefficients of variation of V E changes were significantly lower during HTs than during ABTs. We conclude that (1) ventilatory responses to HT and ABT are significantly correlated despite differences in the mechanisms of the V E changes; (2) the better reproducibility of the V E response to HT as compared with ABT may be an advantage in clinical practice.
authors.affiliation: Unite de Recherches sur les Adaptations Physiologiques et Comportementales (EA 2088), School of Medicine, Amiens, France. urapc@libertysurf.fr
authors.forename: Belkacem
authors.initials: B
authors.lastname: Bouferrache
authors.forename: Slavi
authors.initials: S
authors.lastname: Filtchev
authors.forename: André
authors.initials: A
authors.lastname: Leke
authors.forename: Michel
authors.initials: M
authors.lastname: Freville
authors.forename: Jorge
authors.initials: J
authors.lastname: Gallego
authors.forename: Claude
authors.initials: C
authors.lastname: Gaultier
mesh_terms: D001944:Breath Tests; D002628:Chemoreceptor Cells / Q000503:physiopathology*; D006801:Humans; D018496:Hyperoxia / Q000503:physiopathology*; D007223:Infant; D007231:Infant, Newborn; D007321:Inspiratory Reserve Volume / Q000502:physiology; D025341:Principal Component Analysis; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012123:Pulmonary Ventilation / Q000502:physiology*; D011897:Random Allocation; D015203:Reproducibility of Results; D013990:Tidal Volume / Q000502:physiology