Flow limitation in normal infants: a new method to obtain forced
expiratory maneuvers from raised lung volumes.
Feher, Andre, Robert Castile, Robert Tepper, Jeff Kisling, Connie
Angeliccio, Dave Filbrun, Robert Flucke.
Departments of Pediatrics: Indiana University Medical Center,
Indianapolis, IN. 46223, and Ohio State University, Columbus, OH.
43205
APStracts 3:0083A, 1996.
Forced expiratory maneuvers generated by rapid thoracic compression
(RTC) have been used to assess airway function in infants. It remains
unclear whether flow limitation(FL) can be achieved in healthy
infants, since low pressure transmission across the chest wall and
inspiratory effort may limit the maximum transpulmonary pressure
developed during the maneuver. We have found that several rapid
inflations to a lung volume set at an airway pressure of 30 cmH2O
(V30) briefly inhibits respiratory effort and allows forced
expiration to proceed from V30 to residual volume(RV). We used a
water-filled esophageal catheter to measure iso-volume pressure flow
(IVPF) curves in seven healthy infants (3-33 months). Forced vital
capacity(FVC) was defined as the volume between V30 and RV. Pressure
transmission between the compression jacket and the esophagus
decreased with decreasing lung volume and averaged 60% and 37%, at
50% and 75% expired FVC, respectively. Subjects demonstrated plateaus
in their IVPF curves at 50%FVC and lower lung volumes. We conclude
that this new methodology enables forced expiratory maneuvers to
achieve flow limitation in healthy infants over at least the lower
portion of their lung volume.
Received 16 November 1995; accepted in final form 18 January
1996.
APS Manuscript Number A1202-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96