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This Article Full Text Full Text (PDF) All Versions of this Article: 105/2/685    most recent 90328.2008v1 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 Zosky, G. R. Articles by Hantos, Z. PubMed PubMed Citation Articles by Zosky, G. R. Articles by Hantos, Z.

The bimodal quasi-static and dynamic elastance of the murine lung

¹Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Subiaco, Western Australia; ²Department of Medical Informatics and Engineering, University of Szeged, Szeged, Hungary; and ³Department of Intensive Care and Neonatology, University Children's Hospital, Zurich, Switzerland

Submitted 26 February 2008 ; accepted in final form 11 June 2008

The double sigmoidal nature of the mouse pressure-volume (PV) curve is well recognized but largely ignored. This study systematically examined the effect of inflating the mouse lung to 40 cm H₂O transrespiratory pressure (P_rs) in vivo. Adult BALB/c mice were anesthetized, tracheostomized, and mechanically ventilated. Thoracic gas volume was calculated using plethysmography and electrical stimulation of the intercostal muscles. Lung mechanics were tracked during inflation-deflation maneuvers using a modification of the forced oscillation technique. Inflation beyond 20 cm H₂O caused a shift in subsequent PV curves with an increase in slope of the inflation limb and an increase in lung volume at 20 cm H₂O. There was an overall decrease in tissue elastance and a fundamental change in its volume dependence. This apparent "softening" of the lung could be recovered by partial degassing of the lung or applying a negative transrespiratory pressure such that lung volume decreased below functional residual capacity. Allowing the lung to spontaneously recover revealed that the lung required 1 h of mechanical ventilation to return to the original state. We propose a number of possible mechanisms for these observations and suggest that they are most likely explained by the unfolding of alveolar septa and the subsequent redistribution of the fluid lining the alveoli at high transrespiratory pressure.

mouse; pressure-volume curve; total lung capacity; forced oscillation technique; lung softening