Measurement of ventilatory system resistance in infants and young children.
The mechanics of the ventilatory system were studied in 29 sleeping infants and young children by the analysis of a passive expiration following an end-inspiratory airway occlusion ('single breath' method). The ventilatory system time constant (tau rs) to compliance ratio yielded the value of ventilatory system resistance (Rrs). The calculated ventilatory system compliance correlated well with the slope of the quasi static pressure-volume curve (r = 0.97). The allometric relationship between Rrs and height (Rrs = 81.9.10(3).Ht (cm)-1.76, r = -0.82) is in agreement with forced oscillation measurements during the first year of life (Wohl et al., 1969). tau rs was found to increase significantly over the first months of life (P less than 0.01).
Laboratoire d'Explorations Fonctionnelles Pédiatriques, Hôpital d'Enfants, Vandoeuvre-lès-Nancy, France.
F
F
Marchal
P
P
Haouzi
C
C
Gallina
J P
JP
Crance
D000403:Airway Resistance; D001696:Biomechanical Phenomena; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008168:Lung / Q000502:physiology*; D008170:Lung Compliance; D008176:Lung Volume Measurements; D008297:Male; D008954:Models, Biological; D011312:Pressure; D013997:Time Factors