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Results for “Pulmonary Diffusing Capacity”

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At least 109 records · Page 6Linked to original sources
PubMed1990

Pulmonary diffusing capacity in adult cystic fibrosis: reduced positional changes are partially reversed by hyperoxia.

In seated adult cystic fibrosis (CF) patients, vascular recruitment of the relatively normal regions of the pulmonary circulation could occur in response to vascular destruction or hypoxia elsewhere in the pulmonary vasculature, thus limiting overall reductions in the single breath CO diffusing capacity (DLcoSB) with advancing disease. The purpose of this study was to determine the extent to which pulmonary capillary recruitment limits reductions in DLcoSB in seated adult cystic fibrosis patients, to define the role of hypoxia, and to develop strategies to improve detection of diffusion abnormalities in this disease. In normal subjects and adult CF patients breathing room air, and in a subgroup, after breathing both 40% and 100% O2 for 20 min, we measured changes (compared to sitting) in the three equation DLcoSB by changing transvascular pressure either with 15 degrees head down position (15 degrees HD), or with high negative inspiratory pressure (HNIP). In CF patients breathing room air, the changes in DLcoSB with both 15 degrees HD and HNIP were significantly smaller (p less than 0.01) than in controls and the positional changes correlated with the degree of airway obstruction. Although CF patients had no significant positional changes in diffusional resistance (1/DLcoSB) breathing room air, the positional changes in 1/DLcoSB after breathing 100% O2 for 20 min were similar in magnitude to the positional changes in normal subjects. We conclude that compensatory pulmonary capillary recruitment occurs in the relatively normal regions of the pulmonary vasculature breathing room air in the resting seated position in CF patients, thus minimizing reductions in DLcoSB in the seated position. This accounts for reduced responses of DLcoSB to both position and HNIP. The improved positional changes in 1/DLcoSB breathing hyperoxic gas mixtures in CF patients suggests that the vascular recruitment breathing room air is partly due to hypoxic vasoconstriction rather than due solely to fixed pathological changes in the pulmonary vasculature.

Adolescent↗
PubMed1975

Influence of body position on pulmonary diffusing capacity in yound and old men.

Steady-state diffusing capacity (DLCOSS2), studied in healthy nonsmokers, was significantly higher in five old men when seated than when supine, but was unchanged in five young men. However, "corrected" for the increased ventilation, it decreased in the young--but not in the old--when erect compared with when supine. The change of DLCOSS2 in the young during the first 20 min when seated was related to a change of the fractional dead space ventilation (VD/VT)mThe old showed less venous admixture when seated than when supine, whereas VD/VT and regional ventilation-perfusion index of the lung bases was the same in both positions. The decrease in venous admixture was probably due to the closing capacity (CC) being less than the functional residual capacity (FRC) when seated. The elimination of closed off regions when seated made more pulmonary capillaries available for diffusion.

Adult↗
PubMedDate not supplied

[Pulmonary diffusing capacity in patients with chronic renal failure treated by hemodialysis].

Forty-eight patients with chronic renal insufficiency (CRI) receiving hemodialysis (24 males and 24 females) aged 17-62 underwent bicycle exercise to measure diffuse capacity of the lungs (DCL) before and after the test. DCL components (membraneous and blood volume in pulmonary capillaries, Vc) were defined in 33 out of 48 patients. DCL appeared to reduce significantly (up to 65 +/- 2%) at the expense of Vc fall to 51 +/- 4.5% and membraneous component decline, to 65 +/- 4%. DCL depended on severity of anemia, hemodialysis efficiency, electrolyte metabolism activity and CRI gravity. Performance status in CRI patients is limited by DCL value responsible for maximal oxygen consumption under exercise being independent on duration and type of hemodialysis.

Adolescent↗