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PubMed1981

Allometric analysis of the morphometric pulmonary diffusing capacity in dogs.

The lung volume, the morphometrically determined alveolar and capillary surface area, and the capillary volume of 27 dogs (weight 2.65-57 kg) all were linearly correlated with body weight. The thickness of the air-blood barrier increased only slightly with increasing body size. The structural diffusing capacity, containing these parameters, was used to estimate the gas exchange capabilities of the lung and was also found to scale in direct proportion to body size. This coincides with reports on physiologically estimated diffusing capacity but is obviously different from the interspecies slope for metabolism which scales to the 3/4 power of body weight.

Animals↗
PubMed1980

The effects of acute ethanol ingestion on pulmonary diffusing capacity.

Single breath diffusing capacities for carbon monoxide (DLco) were measured in 12 normal supine subjects before and after ingestion of 15 to 30 ml of 95 percent ethanol (ETOH) to determine if alcohol could acutely change the DLco. Both DLco and specific DLco (DLco/alveolar volume) were significantly decreased 90 minutes after the ingestion of alcohol. This change may be due to a direct effect of alcohol on the alveolar capillary interface by possibly interfering with a carbon monoxide carrier molecule. Another plausible explanation for the reduced diffusing capacity after ingestion of alcohol may be redistribution of blood from the lung to the periphery secondary to the hemodynamic effects of alcohol.

Adult↗
PubMed1991

Factors affecting variations in pulmonary diffusing capacity resulting from postural changes.

The relation of postural changes to the diffusing capacity of the lung for carbon monoxide (DLCO) was investigated in 12 normal nonsmokers in order to evaluate the influence of body position on several components of lung resistance to gas diffusion. The well-known increase in CO diffusing capacity in the supine position was obtained only for data corrected for alveolar volume (KCO: 6.18 +/- 0.75 vs. 5.45 +/- 0.67 ml/min/mm Hg/l; p less than 0.005). Moreover, only the membrane component (Dm) increased significantly in supine subjects (KDm = 2.81 +/- 1.32 vs. 1.82 +/- 0.54 ml/min/mm Hg/l; p less than 0.05), the increase in capillary blood volume (Vc) being not significant (KVc = 12.54 +/- 4.22 vs. 11.17 +/- 3.79 ml/l; NS). These data could be interpreted as a demonstration of a more homogeneously distributed ventilation with respect to diffusion surface in healthy young people in a supine position. The amount of surface available for diffusion seems therefore to be a limiting factor to gas flow across the lungs in these subjects. Thus a straightforward attribution of posturally influenced changes in CO diffusing capacity exclusively to factors affecting Vc is not recommended, particularly in pathological conditions, if information about variation in distribution of ventilation is unavailable.

Adult↗
PubMed1976

Single-breath pulmonary diffusing capacity. Reference values and application in connective tissue diseases and in various lung diseases.

1.1. Diffusing capacity of the lungs was measured by using a Mark 4 Resparameter. The single-breath diffusing capacity (D) for carbon monoxide was found to be dependent on the lung volume (VA) during the breath-hold. The same applied to D/VA and to the time constant (tau) for carbon monoxide uptake. This confirms the theoretical considerations and the results of other investigators. This effect should be taken into account especially when making serial determinations of D on the same subject. 1.2. The repeatability of the method was found to be reasonably good; the coefficient of variation was about 4% in normal subjects, as well as in a series of patients with rheumatoid arthritis. 1.3. The effect of the correction for haemoglobin concentration was calculated and tabulated for a set of possible values of DM/Vc and haemoglobin. This correction did not reduce the scatter of D values in normal subjects, but it was adopted for clinical use for theoretical reasons. Caution in its use and interpretation of the correction is emphasized. 2.1. Healthy males and females, 20-69 years of age, were examined to establish reference values for the D measurement. Multiple linear regression equations were calculated stepwise, and equations based on age and height were then used in the clinical prediction equations. Similarly, prediction equations were calculated for clinical spirometry. 2.2. The prediction equations were compared with some published reference values. The equations provide a basis for the evaluation of the effect of various factors, such as age and smoking, in different populations. 3.1. Respiratory function, clinical symptoms and chest x-ray findings were examined in patients with connective tissue diseases. Three different investigations were thus formed: a) consecutive patients (free of lung disease other than that possibly due to a connective tissue disease) with definite rheumatoid arthritis (RA, 21 cases), systemic lupus erythematosus (SLE, 18 cases) or scleroderma (SCL, 6 cases) were subjected to detailed tests. b) 129 patients from the Rheumatism Foundation Hospital, Heinola, Finland, were subjected to measurement of diffusing capacity and vital capacity in addition to chest radiography and routine clinical assessment c) the histological findings on 12 patients subjected to a needle biopsy of the lung in order to exclude other conditions were compared with the results of diffusing capacity and x-ray examinations. 3.2. Restrictive impairment of the respiratory function was the general finding in all of these groups. The reduction in diffusing capacity was out of proportion to the reduction in lung volume, however, in most cases with abnormally low values. Low D values were encountered in about half of the RA and SLE and in all of the SCL patients in group a, and in 13% of the "average" RA patients studied in Heinola. The typical histological finding in patients with reduced D was a thickening of the alveolar wall...

Adult↗
PubMed1978

[Influence of blood hemoglobin concentration on pulmonary diffusing capacity in man].

CO transfer factor for lungs (TLCO) was measured by a steady state method in 83 subjects (haemoglobin concentration from 60 to 270 g.l-1). TLCO was related with height (T), age (A) and with logarithm of haemoglobin concentration for a non negligeable part : TLCO = 15.45 log Hb + 33.1 T -- 0.06 A -- 51.8. The interest of this relation is discussed.

Adult↗
PubMed1991

Failure of vasoldilator infusion to alter pulmonary diffusing capacity in systemic sclerosis.

PURPOSE: Patients with systemic sclerosis (SSc) do not exhibit a normal increase in the diffusing capacity for carbon monoxide (DLCO) on assuming the supine position. We sought to determine whether a potent prostacyclin derivative and vasodilator, iloprost, would reverse this defect. PATIENTS AND METHODS: Fourteen patients with SSc were enrolled in a randomized, double-blind, placebo-controlled study of iloprost. Patients were tested before and during 3 days of iloprost or placebo infusion with both upright and supine pulmonary function studies. RESULTS: The results of baseline pulmonary function studies including DLCO were not significantly altered by iloprost. Furthermore, iloprost did not alter the abnormal postural DLCO response. CONCLUSION: These results suggest that the pulmonary vascular defects seen in this group of patients are not a consequence of reversible pulmonary vasospasm.

Adult↗