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PubMed1982

Regional diffusing capacity in normal lungs during a slow exhalation.

From an analysis of carbon monoxide uptake and xenon-133 distribution after two bolus inhalations of these gases, we calculated regional diffusing capacity in the upper and lower volume halves of the lungs during the middle 60% of an exhaled vital capacity in five seated normal subjects. We found that the regional diffusing capacity of the upper half of the lungs was 11.6 +/- 4.2 (mean +/- SD) ml.min-1.Torr-1 and that the regional diffusing capacity of the lower half of the lungs was 24.4 +/- 2.4 ml.min-1.Torr-1 after 25% of the vital capacity had been exhaled. These values remained relatively constant as lung volume decreased from 25 to 75% of the exhaled vital capacity. Diffusing capacity in the upper half of the lungs ranged from 9.4 to 12.4 ml.min-1.Torr-1 during exhalation, and in the lower half of the lungs from 21.0 to 28.6 ml.min-1.Torr-1 during exhalation. These results suggest that total lung diffusing capacity remains relatively constant over this midrange of lung volumes and that this occurs because the regional diffusing capacities in both the upper and lower halves of the lungs remain relatively constant.

Adult↗
PubMed1990

Determination of lung capillary blood volume and membrane diffusing capacity in patients with COLD using the NO-CO method.

Lung capillary blood volume (Qc) and the membrane diffusing capacity (Dm) can both be determined from the combined measurement of nitric oxide (NO) and carbon monoxide (CO) transfers using the single-breath method. In ten healthy subjects, no differences was observed between the values of transfer factor of the lungs for carbon monoxide (TLCO) recovered after a 3 s or 9 s breath-holding time (tBH). The NO-CO method could thus be used with a short tBH and a low fraction of inspired nitric oxide (FINO) (8 ppm). However, in ten patients with chronic obstructive lung disease (COLD), the values of both transfer factor of the lungs for nitric oxide (TLNO) and TLCO were underestimated by around 20% at a short tBH (3 s). In COLD patients, the NO-CO method therefore requires a longer tBH and a higher inspired fraction of NO (30 ppm) than in healthy subjects. Similar values of Dm and Qc were obtained using the NO-CO method and the two-step conventional method, at two levels of the oxygenation. The former method gave less scatter. Furthermore, TLNO is independent of the fraction of inspired oxygen (FIO2) and directly proportional to carbon monoxide membrane diffusing capacity (DmCO).

Adult↗
PubMed2005

Radiological findings, pulmonary function and dyspnea in underground coal miners.

BACKGROUND: Respiratory disability induced by dust exposure in coal workers is assessed by pulmonary function tests and radiological evidence of pneumoconiosis. High-resolution computed tomography (HR-CT) improves the visibility of tissue changes, but the value of the findings for the clinical evaluation is controversial. OBJECTIVES: It was the aim of this study to evaluate the correlation between the International Labour Office (ILO) classification and the degree of emphysema in HR-CT with self-reported dyspnea and pulmonary function tests including diffusion capacity for CO (DL,CO). METHODS: We investigated 87 coal miners (aged 67+/-6 years), having worked underground for 26+/-9 years, with pulmonary function tests and HR-CT. Univariate associations were tested with correlation coefficients, and multivariable analyses used a stepwise forward regression model. RESULTS: No aspect of the ILO classification showed a univariate correlation with dyspnea or forced expiratory flow in 1 s (FEV1). Emphysema CT score was strongly associated with DL,CO (rs=-0.40; p<0.001) and FEV1/maximal vital capacity (r=-0.38; p<0.001) in univariate analysis, but not with the clinical grade of dyspnea (r=-0.14; p=0.256). CT emphysema score but not ILO classification was associated with FEV1 in multivariable analyses (rs=-0.37; p<0.001). Dyspnea was best approximated by DL,CO (r=-0.312; p=0.008). CONCLUSION: The clinical grade of breathlessness was best approximated by DL,CO. HR-CT showed a good association with expiratory flow limitation. ILO classification of the chest radiograph may be a marker of exposure but conveys little information about the degree of respiratory impairment.

Coal Mining↗
PubMed1979

Absence of synergism between exposure to asbestos and cigarette smoking in asbestosis.

To assess both independent and synergistic effects of exposure to asbestos and cigarette smoking on the development of asbestosis, survey data from 4 groups of workers exposed to asbestos were analyzed with multivariate statistical models. Survey methods were standardized and included for the 383 subjects a respiratory symptoms questionnaire, occupational history, physical examination, pulmonary function testing, and a chest radiograph. Exposure to asbestos and cigarette smoking were assessed by questionnaire. Synergism between the 2 exposures was not present for previously identified manifestations of asbestosis including bilateral fine crackles, clubbing, dyspnea, radiographic abnormality, decreased forced vital capacity, and decreased single-breath diffusing capacity of the lung for CO. However, additive, independent effects of these 2 exposures were present for each of these parameters.

Adult↗
PubMed2002

Does lung growth occur when mature lobes are transplanted into children?

Lung volume increases after living donor lobar lung transplantation (LD) in children. The mechanism responsible for this increase may be alveolarization (lung growth) or alveolar dilation. The diffusing capacity of the lung for carbon monoxide adjusted for lung volume (DLco/VA) should decrease if alveolar dilation occurs, but not if lung growth occurs. Pulmonary function tests were measured 1-12 months after transplant in 20 children receiving LD transplants and in 11 children receiving cadaveric whole lung transplantation (CL). One month after transplant there were no differences between LD and CL recipients in age, gender, or height. Compared to the first month after transplant, height increased at 6-12 months after LD (p < 0.05), and only at 12 months after CL (p = 0.02). Total lung capacity (TLC) showed an 11-22% increase at 3-12 months after LD, and an 11-14% increase at 6-12 months after CL. DLco/VA showed an 11-17% decrease at 3-12 months after LD. However, in recipients of CL, DLco/VA showed a transient decrease of 10% at 3-6 months post-transplant, but was not significantly lower at 9-12 months. LD recipients had lower DLco/VA values than CL recipients at 6-12 months after transplant (p < 0.05). We conclude that following LD, lung volume increases, but DLco/VA decreases. We speculate that alveolar dilation, rather than alveolarization, is the primary mechanism of increased lung volume in children following LD.

Adolescent↗
PubMed1985

Hyperoxia exposure in mechanically ventilated primates with and without previous lung injury.

The response of the injured lung to hyperoxia is uncertain. In the present study, we evaluated the effects of 100% oxygen exposure for 120-168 h in mechanically ventilated baboons with or without previous diffuse alveolar damage (DAD) induced by oleic acid. These two groups were compared with another group of six baboons previously studied in our laboratory in which DAD induced with oleic acid was followed by ventilation with 40% oxygen. Oleic acid infusion caused a prompt reduction in total lung capacity, static compliance, and diffusion capacity and an increase in lung tissue volume. The magnitude and course of oleic acid lung injury was similar for 4 days in animals breathing 100% or 40% O2. Animals breathing 100% O2 without previous lung injury developed significant decreases in total lung capacity, oxygenation, and diffusion capacity after 72 h of hyperoxia. By 120 h, lung function was similarly impaired in both 100% O2-breathing groups, and rapidly worsening pulmonary edema appeared radiographically between 5.5 and 7 days in all O2-exposed animals. Subsequent weaning was successful in only three animals after 100% O2 exposure. All but one animal in the 40% O2 group were easily weaned. Histologic changes between 6 and 14 days in 100% O2 animals showed a marked proliferative response, particularly of type 2 cells; no differences were found due to prior oleic acid injury. Resolution of this process occurred in a surviving animal, resulting in focal fibrotic residua at 6 weeks, similar to that observed in 40% O2 oleic acid-treated survivors. Previous lung injury due to oleic acid did not modify the response of the baboon lung to hyperoxia.

Animals↗
PubMed2001

Pulmonary function in patients with diabetes mellitus.

BACKGROUND: Pulmonary complications of diabetes mellitus have been poorly characterized. Although some authors have reported normal pulmonary function, others found abnormalities in lung volumes, pulmonary mechanics, and diffusing capacity. SUBJECTS AND METHODS: We studied pulmonary function in a group of patients with diabetes using a combined cardiopulmonary exercise test. Twenty-seven patients with diabetes aged 48 +/- 13 years participated in the study. RESULTS: Overall, forced vital capacity, forced expiratory volume in 1 second, and forced expiratory flow, midexpiratory phase, were within the predicted values, but the residual volume/total lung capacity ratio was slightly elevated. Comparison by diabetes type showed nonsignificant differences in forced expiratory volume in 1 second and forced expiratory flow, midexpiratory phase. Residual volume/total lung capacity ratio was significantly elevated in type 1 patients compared with type 2. Carbon monoxide diffusion capacity (DLCO) was normal in both groups. There was no correlation between the results on pulmonary function test and duration of disease, presence of microangiopathy, or glycemic control. The DLCO was significantly lower in patients with microangiopathic changes, but not when DLCO was corrected for alveolar volume. On the cardiopulmonary exercise test, maximal workload, maximum oxygen uptake, and maximal heart rate were less than predicted, whereas anaerobic threshold and ventilatory reserve were normal. No significant differences were noted in diabetes type, and there was no correlation between parameters of cardiopulmonary exercise test and the other variables. CONCLUSION: Spirometric values are preserved in patients with diabetes mellitus, and there are no defects in diffusing capacity. Cardiovascular factors may account for impaired physical performance. There is no need for routine screening of pulmonary function among diabetic patients.

Adult↗
PubMed1989

Carbon monoxide diffusing capacity of the lungs determined by single-breath and steady-state exercise methods.

We measured carbon monoxide diffusing capacity of the lungs (DL,CO) by both the resting single-breath (SB) and steady-state (SS) exercise methods in 95 patients referred for pulmonary function testing. A 10-second breath-holding method was used for the SB test. DL,CO (SS) was measured during the last minute of a 3-minute exercise test on a 9-inch step. Results of the two methods showed good agreement, the SB-SS difference averaging -0.70 (SD, 3.39) ml/min per mm Hg. The difference between the two methods was not correlated with other measurements of pulmonary function except minute ventilation during the exercise performed in the DL,CO (SS) procedure. In a separate study of laboratory personnel, the day-to-day variabilities of the two tests were similar (SD, 1.4 ml/min per mm Hg). Alveolar volume obtained by helium dilution during the SB test was comparable to total lung capacity (TLC) estimated by multiple-breath nitrogen washout in patients without severe airway obstruction. In severe airway obstruction, the mean SB alveolar volume was 13.8% less than the TLC by nitrogen washout, a difference that may be useful as an indicator of inefficiency of gas mixing in the lungs. We conclude that the SB and SS exercise methods provide similar estimates of DL,CO in patients referred to a pulmonary function laboratory.

Adult↗
PubMed1982

Serial pulmonary function in systemic sclerosis.

The natural history of the pulmonary involvement in systemic sclerosis is not well studied. Reported here are the serial measurements of pulmonary function in a well defined population of patients with systemic sclerosis followed over a mean of 63 months. The mean rate of loss of vital capacity (0.10 liters per year) for the 38 patients serially studied was more than three times the expected rate of loss for a normal population. The mean rate of loss of diffusing capacity (0.33 ml/min/mm Hg per year) for the 27 patients serially studied was similar to that for a normal population. The percent forced vital capacity expired in the first second increased 0.53 percent per year consistent with a progressive restrictive ventilatory defect. Smokers tended to lose vital capacity at a slightly greater rate than nonsmokers (p = 0.069). Individual variability in the course of pulmonary function was observed. Although the overall trend in our population was towards a slowly progressive restrictive ventilatory defect, pulmonary function in the nonsmokers did not change at rates different from those in a nonsmoking reference population.

Adolescent↗