A new technique to generate and assess forced expiration from raised lung volume in infants

Turner, D.J., Stick, S.M., Lesouef, K.L., Sly, P.D. and LeSouef, P.N. (1995) A new technique to generate and assess forced expiration from raised lung volume in infants. American Journal of Respiratory and Critical Care Medicine, 151 5: 1441-1450.

Author Turner, D.J.
Stick, S.M.
Lesouef, K.L.
Sly, P.D.
LeSouef, P.N.
Title A new technique to generate and assess forced expiration from raised lung volume in infants
Journal name American Journal of Respiratory and Critical Care Medicine   Check publisher's open access policy
ISSN 1073-449X
1535-4970
Publication date 1995-05-01
Sub-type Article (original research)
Open Access Status Not Open Access
Volume 151
Issue 5
Start page 1441
End page 1450
Total pages 10
Place of publication New York, NY, United States
Publisher American Thoracic Society
Language eng
Formatted abstract
We have developed a new technique that allows assessment of infant lung function over an extended volume range. The lungs are rapidly inflated to a predetermined inflation pressure (PP) using a modified diaphragm pump. Forced expiratory flow-volume (FEFV) curves are then generated from raised lung volumes using an inflatable plastic jacket. We studied 26 normal infants with a median age of 14 mo (range, 3 to 23 too). FEFV curves were obtained in each infant from end-tidal inspiration and from lung volumes set by a range of PP (15 to 20 cm H2O). Mean (SE) volume above FRC was 107 ml (9 ml), and mean forced expiratory time was 0.73 s (0.05 s) at end-tidal inspiration. Both measurements increased progressively with increases in PP to 251 ml (13 ml) and 1.04 s (0.06 s), respectively, at 20 cm H2O PP (p < 0.0001). Mean intrasubject coefficient of variation was 15.5% (95% confidence interval, 12 to 19%) for maximal flow at FRC, but it was less than 6% (95% Cl, 4 to 8%) for forced expiratory volume-time (FEV(t)) measurements at all levels of PP. Twenty-seven recurrently wheezy infants with a median age of 13 mo (range, 6 to 18 too) were subsequently studied using a PP of 17.5 cm H2O. Wheezy infants had a lower V̇maxFRC [mean (1.39 ml/s/cm) and 95% Cl (1.15 to 1.63 ml/s/cm)] than did normal infants (1.78, ml/s/cm; Cl, 1.51 to 2.05) (p < 0.05). FEV1 measurements were all lower in wheezy infants than in normals infants: mean FEV0.5, 1.86 ml/cm (Cl, 1.73 to 1.98) and 2.31 ml/cm (Cl, 2.15 to 2.48), respectively (p < 0.0001); FEV0.75, 2.20 ml/cm (Cl, 2.07 to 2.32) and 2.72 ml/cm (Cl, 2.52 to 2.91), respectively (p < 0.0001); FEV1.0, 2.42 ml/cm (Cl, 2.26 to 2.58) and 2.84 ml/cm (Cl, 2.63 to 3.06), respectively (p < 0.005). The Cl values of each FEV1 measurement did not overlap between the wheezy and normal groups; however, the Cl values of V̇maxFRC overlapped markedly. In addition, FEV1 parameters showed greater sensitivity in detecting reduced lung function (71 to 89%) than did V̇maxFRC parameters (56%). We conclude that (1) FEV1 measurements derived from a lung volume set by a standardized pressure are more reproducible than flow measurements in the tidal volume range; (2) FEV1 measurements are significantly lower in wheezy infants than in normal infants, show less overlap than flow measurements in the tidal volume range, and therefore are better able to separate the two populations.
Keyword Respiratory illnesses
Flow
Responsiveness
Newborn
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Medicine Publications
 
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