Comparison of the hyperoxic test and the alternate breath test in infants. |
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Authors: | Belkacem Bouferrache Slavi Filtchev André Leke Michel Freville Jorge Gallego Claude Gaultier |
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Affiliation: | Unite de Recherches sur les Adaptations Physiologiques et Comportementales (EA 2088), School of Medicine, Amiens, France. urapc@libertysurf.fr |
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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. |
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