HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplemental Videos All Versions of this Article: 106/6/1888    most recent 91526.2008v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Siew, M. L. Articles by Hooper, S. B. PubMed PubMed Citation Articles by Siew, M. L. Articles by Hooper, S. B.

Inspiration regulates the rate and temporal pattern of lung liquid clearance and lung aeration at birth

¹Department of Physiology, ²School of Physics, ³Monash Centre for Synchrotron Science, and ⁴Department of Biological Engineering, Monash University, Melbourne; ⁵The Division of Newborn Services, Royal Women's Hospital, Carlton, Victoria, Australia; and ⁶SPring-8, Japan Synchrotron Radiation Research Institute, Sayo, Hyogo, Japan

Submitted 24 November 2008 ; accepted in final form 31 March 2009

At birth, the initiation of pulmonary gas exchange is dependent on air entry into the lungs, and recent evidence indicates that pressures generated by inspiration may be involved. We have used simultaneous plethysmography and phase-contrast X-ray imaging to investigate the contribution of inspiration and expiratory braking maneuvers (EBMs) to lung aeration and the formation of a functional residual capacity (FRC) after birth. Near-term rabbit pups (n = 26) were delivered by cesarean section, placed in a water plethysmograph, and imaged during the initiation of spontaneous breathing. Breath-by-breath changes in lung gas volumes were measured using plethysmography and visualized using phase-contrast X-ray imaging. Pups rapidly (1–5 breaths) generate a FRC (16.2 ± 1.2 ml/kg) by inhaling a greater volume than they expire (by 2.9 ± 0.4 ml·kg^–1·breath^–1 over the first 5 breaths). As a result, 94.8 ± 1.4% of lung aeration occurred during inspiration over multiple breaths. The incidence of EBMs was rare early during lung aeration, with most (>80%) occurring after >80% of max FRC was achieved. Although EBMs were associated with an overall increase in FRC, 34.8 ± 5.3% of EBMs were associated with a decrease in FRC. We conclude that lung aeration is predominantly achieved by inspiratory efforts and that EBMs help to maintain FRC following its formation.

fetus; expiratory braking maneuvers