Peripheral chemoresponses of infants measured by a minimally invasive method utilizing two-breath alternations in Fl,02.
The aim of this study was to develop a minimally invasive and reliable method for measuring peripheral chemoresponsiveness to oxygen in infants, and to establish baseline data from normal infants at 12 weeks of age. Two-breath alternations in fractional inspired oxygen (FI,O2), switching between 0.42 to 0.00 were given for 2 min periods via a face mask (held close to the face but without contact) to 18 healthy infants during quiet sleep. End-tidal oxygen concentrations alternated between 21 and 11%. Instantaneous minute ventilation (V'E) and its components tidal volume (VT), respiratory frequency (fR) inspiratory and expiratory times (tI and tE), inspiratory flow (VT/tT), and inspiratory duty cycle (tI/ttot) were measured by respiratory inductance plethysmography. Two-breath alternations in each of the ventilatory components were matched with the corresponding alternating end-tidal oxygen record and compared with contiguous pre- and post-test data obtained in control periods of air breathing. Alternations in all ventilatory components except fR changed significantly during FI,O2 alternations; VT 26%, tE-8%, VT/tI 18%, tI/ttot 11% and V'E 28% of baseline values. Within and between infant variances are reported for the individual components of ventilation. Differences among infants were best detected by alternations in V'E; within infant variance 76, between infant variance 171. We conclude that the test described is a safe, reliable and relatively easily applied method of measuring peripheral chemoresponsiveness, which is suitable for clinical application in infancy.
Thomas
D A
DA
Dept of Child Health, University of Leicester, Leicester Royal Infirmary, UK.
Poole
K
K
McArdle
E K
EK
Beardsmore
C S
CS
Goodenough
P C
PC
Thompson
J
J
Simpson
H
H
D000704:Analysis of Variance; D001944:Breath Tests / Q000379:methods; D002628:Chemoreceptor Cells / Q000502:physiology; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D010991:Plethysmography; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology*; D012119:Respiration / Q000502:physiology; D012129:Respiratory Function Tests; D012680:Sensitivity and Specificity