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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↗
PubMed1980

Pulmonary diffusing capacity and its components (DM and Vc) in young, healthy smokers.

We have studied the diffusing capacity and its components (DM and Vc) in two groups of 9 males, healthy, smokers and nonsmokers, with similar age, biometric characteristics and spirographic values. Also, BT was not different between the two groups, because the smokers were asked to stop smoking 12 h before the test. Our data showed that TF and DM are significantly lower in smokers than in nonsmokers (p less than 0.005 and less than 0.01, respectively, while Vc was not different between the two groups and confirm that Vc is influenced by COhb level.

Adult↗
PubMed1975

Morphometric estimation of pulmonary diffusion capacity. VII. The normal Guinea pig lung.

A study of 15 normal adult guinea pig lungs fixed by instillation of fixatives via the airways is described. The morphological appearance of the guinea pig lung is similar to that of other mammals apart from quantitative differences in the mass of connective tissue in the alveolar-capillary barrier whose mean thickness was estimated at 1.59 mum. Lung volume, alveolar volume, capillary volume and the surface areas of alveoli and capillaries are shown to be linearly related to body weight. Analysis of the morphometric diffusion capacities of the alveolar-capillary membrane and of the lung shows that these are also linearly related to body weight. For a mean body weight of 429 g the lung volume was 13 ml, the alveolar surface 0.91 m2, the capillary volume 1.5 ml, the harmonic mean barrier thickness 0.42 mum, and DL 2.13 ml/min.mm Hg. These parameters are compared with those of other mammalian species and discussed in the context of normal activity levels as a probable important adaptive factor determining the size of the gas exchange apparatus.

Animals↗
PubMed1981

Design of the mammalian respiratory system. IV Morphometric estimation of pulmonary diffusing capacity; critical evaluation of new sampling method.

The quality of morphometric data obtained by stereological methods depends on the sampling scheme adopted. In the light of recent advances in sampling theory for stereology a sampling strategy has been developed which differs significantly from that used in previous studies. It operates with a cascade of four sampling levels and adopts the principle of A-weighted sampling, a method that should eliminate bias and possibly yield smaller variances. This method is described and discussed in detail. When compared with the old simpler sampling approach it is found that the new method (1) is at least as efficient and (2) that the estimates of morphometric parameters obtained by this method are similar to the data generated by the old method.

Animals↗
PubMed1981

Pulmonary diffusing capacity and physical working capacity in swimmers and non-swimmers during growth.

We measured physical working capacity at a heart rate of 170 bpm (PWC170) and diffusing capacity for carbon monoxide (DLCO) in two groups of children ranging in age from 9 to 17 years. One group was formed of highly trained competitive swimmers and the other of age, sex and size matched untrained counterparts. Bicycle ergometry was used to establish PWC170. The DLCO was measured at rest (DLCO rest) and while pedalling at 170 bpm (DLCO ex). The PWC 170, DLCO rest and DLCO ex were significantly higher in swimmers than in non-swimmers. Repeated measurements in the same subjects show that individual increases in DLCO rest and DLCO ex were result of both growth and training.

Adolescent↗
PubMed1990

Pulmonary diffusing capacity in left ventricular dysfunction.

The purpose of this study was to determine whether there are any consistent spirometric or Dsb findings in patients with LV dysfunction characterized by a clinical diagnosis of CHF and an EF less than 40 percent. We performed spirometry and Dsb in 34 patients, and found that EF correlated only with Dsb. When we separated the patients into those with rales and those without, Dsb correlated strongly with EF only in those with rales. There was no correlation with other spirometric values. Mean Dsb percent predicted was significantly lower in patients with rales despite similar mean EF. Only two of 23 patients without rales had a reduced Dsb while only one of 11 with rales had a normal Dsb. We conclude that Dsb is a good predictor of clinically evident heart failure. When rales are absent, Dsb should be normal in patients with LV dysfunction; when present, Dsb will be diminished in proportion to the EF.

Aged↗
PubMed1983

Maximal oxygen consumption and pulmonary diffusing capacity: a direct comparison of physiologic and morphometric measurements in canids.

The purpose of this study was to check the validity of the morphometric model for estimating physiological conductances for gases, DL. We make a direct comparison between the lung's conductance for carbon monoxide, measured physiologically using the single breath method, DLCO (sb), and that measured morphometrically using the previously published model, DLCO(mm). We also make a direct comparison between the maximum rate of oxygen uptake by the lung during exercise, VO2max, and the lung's conductance for oxygen DLO2(mm). We made these measurements on four species of canids (foxes, coyotes, dogs and wolves). We find a direct proportionality between morphometric and physiologic DLCO measurements, the morphometric being consistently larger by a factor of two. We also find that both DLCO and DLO2 increase more steeply with body mass than VO2max, the difference between the allometric slopes being the same as we had found previously in a wide range of mammalian species ranging from 2 g to 700 kg, although the slopes themselves were different. We conclude that the discordant scaling of DLO2 and VO2max with respect to body mass is not an artifact of the model for calculating DLO2 from morphometric data.

Animals↗
PubMedDate not supplied

Pulmonary diffusing capacity for carbon monoxide in simple coal workers' pneumoconiosis.

The lung diffusing capacity for carbon monoxide (DLCO single-breath) and its two components, the capillary blood volume (Vc) and the diffusing capacity of the membrane (DMCO) were measured at rest in 43 miners and 141 control subjects, the values in whom enabled reference formulae to be established; in 30 control subjects and in the majority of the miners these indices were measured during exercise. The main results are as follows: the diffusion indices are on average slightly decreased in simple coal workers' pneumoconiosis; both DMCO and Vc contribute to the lowering of DLCO, at rest and during exercise; individually Vc is more often significantly altered than DMCO; on effort the percentage increase of DLCO is normal in coal miners; the data during exercise suggest that smoking habit contributes more to lowering DLCO than does pneumoconiosis itself; lastly the diffusion indices are lower in miners with "pin-head" than those with micronodular opacities: this tendency is more pronounced during exercise. These findings are discussed.

Adult↗