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PubMed1990

Pulmonary membrane diffusing capacity and capillary blood volume in tropical eosinophilia.

Pulmonary membrane diffusing capacity (Dm) and pulmonary capillary blood volume (Vc) measurements were carried out in 21 patients with untreated tropical eosinophilia and 21 healthy controls matched for age, sex, height, and smoking habit. The mean single breath transfer factor (Dco) and the mean membrane diffusing capacity were significantly lower (p less than 0.001) in patients with tropical eosinophilia compared with control subjects. However, the mean capillary blood volume was not significantly different (p greater than 0.2). The positive correlations between Dm and transfer factor (r = 0.825), between Dm and effective alveolar volume (VA) (r = 0.721), and between Dco and VA (r = 0.774) were also highly significant (p less than 0.001) in study patients prior to treatment. These data suggest that reduction in single breath transfer factor in untreated tropical eosinophilia may be due to a reduction in membrane diffusing capacity, which in turn may be due to a reduction in area of membrane available for diffusion, as evidenced by the significantly reduced VA (p less than 0.001) in these patients. Since pulmonary capillary blood volume was normal, the pulmonary perfusion was within normal limits. Following three weeks of treatment with diethylcarbamazine citrate, although there was a significant rise in single breath transfer factor (p less than 0.001) and membrane diffusing capacity (p less than 0.05), both Dco (p less than 0.01) and Dm (p less than 0.01) continued to be significantly lower than those of control subjects. However, pulmonary capillary blood volume did not show any change (p greater than 0.2).

Adult↗
PubMed1989

Measurement of diffusing capacity in pulmonary embolism.

Pulmonary function tests were carried out in 20 consecutive patients with pulmonary embolism (PE), diagnosed on the basis of a positive ventilation-perfusion lung scan carried out within 72 h of admission. Changes in forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and arterial blood gas tensions were too variable to be helpful diagnostically. In contrast, transfer factor (diffusing capacity) of the lung (TLCO) was significantly reduced in all cases and, in spite of a period of anticoagulation, tended to remain subnormal during a follow-up period of up to 3 years. Lung scans, however, tended to return to normal within 3 months of the incident. Thus, a reduction of TLCO to below 75% of the predicted normal was found in all cases with abnormal lung scans and such measurements provide a useful and simple screening test for PE; a normal TLCO would effectively exclude such a diagnosis. The failure of TLCO to return to normal in the majority of cases suggests persistence of the underlying physiological defect, in spite of normalization of symptoms and lung scans following anticoagulation.

Adult↗
PubMed1991

The effects of D/Q and D/VA inequalities on pulmonary oxygen diffusing capacity estimates.

Bohr-integrated estimates of steady-state pulmonary diffusing capacity for oxygen (DLO2) were calculated using lung compartments with different VA/Q ratios. Compartmental diffusing capacity was distributed in proportion to either ventilation or blood flow. This method was applied to 115 gas exchange data sets previously collected from healthy human subjects during normoxic (PIO2 = 148 Torr) or acute hypoxic (PIO2 = 80 Torr) exercise. Ventilation-weighted estimates of oxygen diffusing capacity exceeded blood flow-weighted estimates by 10 and 78% during hypoxia and normoxia, respectively. While blood flow-weighted DLO2 estimates during heavy exercise were greater in hypoxia than in normoxia (mean +/- SEM of 87.1 +/- 4.4 vs 53.0 +/- 3.1 ml.min-1.Torr-1), ventilation-weighted estimates were not significantly different (93.2 +/- 5.5 vs 96.3 +/- 9.4 ml.min-1.Torr-1). These results show that the effect of D/Q inequality on DLO2 estimates is greater at higher levels of inspired oxygen. Furthermore, a D/Q mismatch of similar magnitude as the VA/Q mismatch that is observed during heavy exercise can account for a previously observed discrepancy between normoxic and hypoxic oxygen diffusing capacity estimates.

Humans↗
PubMed1996

[Diagnostic value of exercise diffusion capacity test on diffuse pulmonary fibrosis].

Diffusion capacity for carbon monoxide of the lung (DLCO) before-and-after exercise test and 5 routine pulmonary function tests were conducted in 16 patients with diffuse pulmonary fibrosis (DPF), 19 patients with interstitial pneumonia (IP), 17 patients with COPD, and 22 normal subjects. The data showed: in normal subjects the DLCO after exercise increased significantly compared with before (P < 0.001). But in DPF group the DLCO before exercise was below the normal range, and it went down further after exercise, the decreasing rate being 17.95% (P < 0.001). The DLCO in IP and COPD groups did not significantly change before and after the exercise. Two cases of interstitial pneumonia, who had a reduced DLCO after exercise, were followed up for 0.5-1.0 year, and both patients developed into DPF by that time. The results suggest that the DLCO measure before and after exercise test may have important value for DPF diagnosis, and a reduced DLCO after exercise test in IP patients may warn the development from IP into DPF.

Adult↗
PubMedDate not supplied

Rebreathing and single breath pulmonary CO diffusing capacity in man at rest and exercise studied by C18O isotope.

The pulmonary diffusing capacity for carbon monoxide, Dco, was estimated in normal subjects, using both a single breath technique (DcoSB) and a rebreathing technique (DcoRB). In order to measure CO by mass spectrometry, the stable isotope C(18)O was used. In three normal subjects Dco was measured at different lung volumes at rest, and at different levels of bicycle exercise. DcoRB was found on the average 30% higher than DcoSB when compared at the same mean lung volume, and both increased slightly during exercise. The advantages and drawbacks of the rebreathing method are critically discussed.

Acetylene↗
PubMed1987

[Lung diffusion capacity of pulmonary tuberculosis patients].

DLCO, DL/VA, Dm and Vc, lung volumes, capacities and values of a curve representing flux-forced expiration volume relationships were investigated in 159 patients with focal, infiltrative, disseminated and fibrocavernous tuberculosis. A decrease in DLCO was observed in half of the patients with disseminated and fibrocavernous tuberculosis and in less than one/fifth of the patients with focal and infiltrative tuberculosis. The leading factor of a decrease in DLCO in the patients with disseminated and fibrocavernous tuberculosis was the reduction of the lung respiratory surface resulting from a decrease in the effective alveolar volume; the leading factor in infiltrative tuberculosis was a decrease in alveolocapillary membrane permeability. In focal tuberculosis the importance of the above factors in DLCO reduction was approximately the same.

Adolescent↗
PubMed1980

Membrane diffusing capacity and pulmonary capillary volume in rheumatoid disease.

In some patients with rheumatoid disease gas transfer across the lungs is abnormal. We measured the membrane component of gas transfer (Dm) and pulmonary capillary volume (Vc) in 48 patients with rheumatoid arthritis and in 48 normal volunteers matched for age, sex, and smoking habits. Volunteers had normal chest radiographs and normal forced expiratory volume in one second and vital capacity. There were no significant differences between the rheumatoid and control groups for Dm. Mean Vc in rheumatoid male smokers (64.0 ml, SD 16.5) was significantly lower than in control male smokers (76.3 ml, SD 18.0 p less than 0.05). In rheumatoid female smokers mean Vc (43.4 ml, SD 13.3) was significantly lower than in rheumatoid female non-smokers (58.4 ml, SD 15.4 p less than 0.01). There was no significant difference between rheumatoid and control female non-smokers (mean Vc 58.4 ml and 60.7 ml respectively). Significant differences in Vc in terms of per cent predicted normal were found between patients receiving corticosteroids and those not receiving corticosteroids or penicillamine (p less than 0.02) and between patients with nodules and those without (p less than 0.05). Patients with persistently low transfer factor for five years had a significantly lower Vc (p less than 0.02). There was no consistent correlation between Dm and Vc and dynamic compliance or static recoil pressure. It appears that the abnormality of transfer factor in rheumatoid disease previously demonstrated is caused by reduction of Vc. It seems that involvement of pulmonary blood vessels occurs in patients with nodules and is suppressed by treatment with corticosteroids.

Arthritis, Rheumatoid↗
PubMed1999

Body position, membrane diffusing capacity and pulmonary capillary blood volume in chronic bronchitis and pulmonary emphysema.

BACKGROUND: The effect of body position on diffusing capacity and its components, membrane diffusing capacity (Dm) and pulmonary capillary blood volume (Vc), in patients with chronic obstructive pulmonary disease (COPD) has remained elusive. This study was designed to evaluate the effect of body position on diffusing capacity for carbon monoxide (DLco), Dm and Vc in male patients with chronic bronchitis and pulmonary emphysema. METHODS: Pulmonary function tests including spirometry and lung volume were assessed in the erect position, and DLco, Dm and Vc were measured in the erect and supine positions in a random order in 17 men with chronic bronchitis and 19 men with pulmonary emphysema. RESULTS: Spirometry results and lung volumes were comparable between both groups of patients; however, significantly lower values of DLco and Kco (DLco corrected by alveolar volume, VA) were observed in the emphysema than in the bronchitis group. In the bronchitis group, Kco and Vc were significantly higher in the supine than in the erect position, but Dm was significantly lower in the supine position. Alternation of body position did not significantly affect DLco and its components in the emphysema group. DLco, Kco and Vc in both the erect and supine positions were significantly higher in the bronchitis than in the emphysema group. Vc-SE (SE, the data in the supine minus those in the erect position) was also significantly higher in the bronchitis group. In the bronchitis group, DLco-SE was significantly correlated with Dm-SE and Vc-SE. However, Kco-SE was highly correlated with Dm-SE. In the emphysema group, DLco-SE and Kco-SE were highly correlated with Vc-SE only. CONCLUSIONS: An increase in Vc in the supine position may account for the postural effect on Kco in bronchitis patients. In patients with pulmonary emphysema, decreased DLco and an absence of postural effect on DLco and its components may be due to a widespread abnormality of the pulmonary capillary bed. These findings may be of value in elucidating the difference in mechanisms of impaired gas exchange between patients with chronic bronchitis and pulmonary emphysema.

Aged↗
PubMed1989

Gas exchange in the lung of a dasyurid marsupial: morphometric estimation of diffusion capacity and blood oxygen uptake kinetics.

Placental and marsupial mammals differ in the balance of their cardio-respiratory systems. To determine if differences also occur in lung structure, a morphometric study of the lungs of a dasyurid marsupial, Dasyuroides byrnei, was undertaken. The total lung volume was large, but a comparatively smaller proportion was devoted to gas exchange tissue. Eighty-seven percent of lung parenchyma was air space. The volume of capillary blood was lower than would be predicted on a body mass basis, but the hematocrit was high (55%). The rate of oxygen uptake by the blood of D. byrnei was not different from that of recent determinations on human blood. However, a large oxygen capacity resulted in a high theta O2. Morphometric data were used, with theta O2 calculated for D. byrnei, to estimate the pulmonary diffusion capacity. Mass specific DLO2 was high by comparison to those reported for placentals. The erythrocytes contributed 70% of the diffusion resistance to oxygen transfer, with the large theta O2 counteracting the low Vc. We conclude that, similarly to placentals, lung structure is unlikely to limit oxygen transport in this animal, although the structural emphasis appears to be geared towards maximising alveolar ventilation.

Animals↗
PubMed1992

Effects of body position and age on membrane diffusing capacity and pulmonary capillary blood volume.

The effects of body position and age on the membrane diffusing capacity (Dm), pulmonary capillary blood volume (Vc), and the single breath carbon monoxide diffusing capacity (Dco) were evaluated in the erect (sitting) and supine positions in 16 normal young men (under 40 years old, younger group) and in 13 older men (over 40 years old, older group). Dm and Vc were estimated by several measurements of the Dco at increasing alveolar oxygen tension (PAO2). The results showed that Dco, Dm, Vc, and Kco (Dco corrected by alveolar volume) decreased with age in both positions. The differences in Dco, VC, and Kco between the two positions (supine minus the erect position) also decreased with age. The mechanisms of the increases in Dco in the supine position remain to be explained but may be due to a change in pulmonary capillary shape from an elliptical (erect position) to a circular configuration (supine position) since Vc increased more than Dm on assuming the supine position. The findings may be of clinical importance since many physicians have attempted to utilize a reduction in the positional change in Dco as a potential marker of disease.

Adult↗
PubMed1996

Measurements of membrane diffusing capacity and pulmonary capillary blood volume in normal subjects and patients with mild emphysema.

OBJECTIVE: To establish predicted values of membrane diffusing capacity (Dm) and pulmonary capacity blood volume (Vc), to compare the predicted values from our equations with those for Caucasians, to determine whether there are changes initially in Dm or Vc in patients with mild emphysema. PATIENTS AND METHODS: Diffusing capacity for carbon monoxide (DLco), Dm and Vc were determined in 86 normal subjects and 16 patients using the single-breath diffusing capacity for carbon monoxide (DLcosB) with two different alveolar concentrations of oxygen. RESULTS: The predicted equations are as follows. For males, DLco (ml/min/mm Hg) = 0.37H-0.19A-27.8; Dm (ml/min/mm Hg) = 0.65H-0.24A-53.7; Vc(ml) = 0.88H-78.9. For females, DLco = 0.28H-22.7; Dm = 0.59H-53.6; Vc = 66.6-0.36A. DLco and Vc are lower in Chinese than Caucasians while Dm is similar in Chinese and Caucasians. Eleven of 16 patients had a low DLco (< 80% predicted value), 12 had a low Dm and 5 had a low Vc. Eight of 12 patients with a low Dm also had a low DLco, but in 4 the DLco was normal. Nine of 12 with low Dm had a normal Vc. CONCLUSIONS: This study provides prediction equations of Dm and Vc. Chinese have a low DLco because their Vc is lower than Caucasians. The DLco and Dm are abnormal in a comparable percentage of patients. In patients with mild emphysema, the Dm becomes abnormal before the Vc.

Adolescent↗
PubMed1985

Lung function studies of asbestos workers.

Pulmonary function tests have been conducted on 155 asbestos workers and 130 referents. It was found that the lung function impairment in asbestos workers is predominantly a restrictive ventilatory defect appearing even when radiographic changes are not detectable. There was, however, no evidence of airway obstruction. As the disease progressed, all the pulmonary function indices, including vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), maximal ventilation volume (MVV), total lung capacity (TLC), and pulmonary diffusing capacity (DLCO), were reduced dramatically, with the exception of FEV1.0/FVC(%). It is suggested that both radiographic examination and pulmonary function tests should be used as early detection measures of asbestos-induced lung disorders. VC, FVC, and FEV1.0 are the simplest, most reproducible, and most valid indices for the health surveillance of asbestos workers, while the FVC test is the most valuable for epidemiologic study. With stepwise regression analysis a quantitative relationship between dust exposure and pulmonary function was demonstrated. There was no significant difference in the small airway function of the exposed workers and the referents. Further study is needed to investigate the possibility of asbestos-induced small airway obstruction and to estimate the roles played by cigarette smoking and air pollution.

Adult↗
PubMed1977

Clinical pharmacologic and therapeutic studies of bleomycin given by continuous infusion.

The clinical toxicology, clinical pharmacology, and therapeutic effects of bleomycin given by continuous intravenous infusion were studied in patients with far-advanced unresectable cancer. The toxicity of bleomycin given by that schedule was qualitatively and quantitatively the same as when it was given by daily intravenous "push"; mucocutaneous toxicity occurred regularly after 7-11 days of infusion. Careful monitoring of pulmonary function revealed minor changes in Total Lung Capacity and Pulmonary Diffusion Capacity in nearly all patients; however, overt pulmonary toxicity occurred in only six patients (5%). 111Indium-labeled bleomycin was used to follow blood levels of bleomycin; it correlated well with the levels determined by microbiologic assay and could be measured at levels lower than could be determined by bioassay. Useful therapeutic responses were seen in a variety of tumors; 30% patients with very far-advanced carcinoma of the cervix demonstrated CR or PR, an incidence higher than has been seen with other regimens. Sixty-nine percent of patients with disseminated germ cell neoplasms of the testis, refractory to bleomycin given by conventional dose schedules, have attained partial remission through the continuous infusion of bleomycin.

Bleomycin↗