The hyperoxic test in infants reinvestigated.

The hyperoxic test (HT) examines peripheral chemoreceptor function (PCF) by measuring the decrease in ventilation (V E) after 100% O(2) inhalation. A 30-s HT has been previously used in infants with calculation of the ventilatory response (VR) as the mean percentage change in V E during HT as compared with normoxia. However, it has been shown that during hyperoxia V E rises secondarily after the initial drop because of loss of PCF.

Reproducibility of the alternating breath test of fractional inspired O2 in infants.

We conducted a reproducibility study of the alternating breath test (ABT) for assessing peripheral chemoreceptor function in infants. The ABT delivers a rapid hypoxic stimulus to the peripheral chemoreceptors with breath-by-breath alternations of the inspired O2 fraction. The reproducibility of the ABT performed on a single occasion has not been extensively studied in infants.