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This Article Full Text Full Text (PDF) All Versions of this Article: 582/2/767    most recent jphysiol.2007.133405v1 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 Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Glénet, S. N. Articles by Guénard, H. J. P. Search for Related Content PubMed PubMed Citation Articles by Glénet, S. N. Articles by Guénard, H. J. P. Related Collections Respiratory

¹ Laboratoire de Physiologie, Université Victor Segalen Bordeaux II, CHU de Bordeaux, 33760, Bordeaux Cedex, France
² Laboratoire des Adaptations Physiologiques aux Activités Physiques, Faculté des Sciences du Sport Poitiers, UPRES-EA 3813, France
³ Service de réanimation médical, CHU de Bordeaux, France

Using simultaneous nitric oxide and carbon monoxide lung transfer measurements (T_LNO and T_LCO), the membrane transfer capacity (D_m) and capillary lung volume (V_c) as well as the dimensionless ratio T_LNO/T_LCO can be calculated. The significance of this ratio is yet unclear. Theoretically, the T_LNO/T_LCO ratio should be inversely related to the product of both lung alveolar capillary membrane (µ) and blood sheet thicknesses (K). NO and CO transfers were measured in healthy subjects in various conditions likely to be associated with changes in K and/or µ. Experimentally, deflation of the lung from 7.4 to 4.8 l decreased the T_LNO/T_LCO ratio from 4.9 to 4.2 (n = 25) which was consistent mainly with a thickening of the blood sheet. Compared with continuous negative pressure breathing, continuous positive pressure breathing increased this ratio suggesting a thinning of the capillary sheet. It was also observed with 12 healthy subjects that slight haemodilution that may thicken the blood sheet decreased the T_LNO/T_LCO ratio from 4.85 to 4.52. In conclusion, the T_LNO/T_LCO ratio is related to the thickness of the alveolar blood barrier. This ratio provides novel information for the analysis of the diffusion properties.

(Received 26 March 2007; accepted after revision 30 April 2007; first published online 10 May 2007)
Corresponding author H. Guénard: Laboratoire de Physiologie, Université Victor Segalen, 146 Rue Léo Saignat, 33076 Bordeaux Cedex, France. Email: herve.guenard{at}labphysio.u-bordeaux2.fr

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