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PubMed1976

[Diffusion disorders in patients with liver cirrhosis].

In 17 patients with cirrhosis of theliver and in 11 controls the pulmonary diffusing capacity for CO (DLCO) was determined at three different levels of alveolar oxygen tensions. The diffusing capacity of the alveolar membrane (DMCO) and the intra-pulmonary capillary volume (VC) were calculated following the formula given by Roughton and Forster. The following results were obtained: 1) Both DLCO and DMCO were lower (p less than 0,01) in the patient group than in the controls. 2) VC showed larger variations in thepatient group than in the controls (p less than 0,01). The mean values did not differ, however. 3) There was a significant linear correlation (p less than 0,001) between DM and 1/VC in the patient group (DM and VC in % of the predicted value). The results suggest, that a change in the configuration of the capillary bed may be responsible for the transfer defect found in cirrhosis.

Adult↗
PubMed2001

Pulmonary diffusion abnormalities in relation to cytomegalovirus antigenemia and cytomegalic endothelial cells in blood.

The pathophysiology of HCMV infection may involve many different organs including the lungs. In this study we investigated HCMV antigenemia levels and cytomegalic endothelial cells (CEC) in blood in relation to the pulmonary diffusion capacity. Patients with high HCMV antigenemia (> or = 100 pp65+ PMNs/50.000) (n = 8) showed a more extensive decrease in the membrane factor (Dm) than patients with lower levels of HCMV antigenemia (n = 7). The decline of the diffusion capacity of the alveolar capillary membrane (KCOc) and of the pulmonary capillary volume (Vcap) was the same in both groups. Four out of nine patients had CEC in the range of 0.22 CEC/ml to 30.26 CEC/ml. All the HCMV patients showed a decreased KCOc together with a decrease of Dm and Vcap but no difference was observed between patients with and without CEC. We conclude that a higher viral load is associated with a more extensive decrease in the membrane factor and therefore with more subclinical pneumonitis. No relation was observed between CEC and pulmonary dysfunction. Therefore, we postulate that CEC levels are related indirectly to subclinical pneumonitis mediated via the viral load.

Adult↗
PubMed1993

Pulmonary function after successful heart transplantation. One year follow-up.

Congestive heart failure (CHF) has been associated with the development of restrictive ventilatory abnormalities and decreased pulmonary diffusing capacity. Whether these physiologic changes reflect permanent alterations of lung anatomy or result solely from potentially reversible alterations of lung water is not known. To examine this issue, we reviewed the pulmonary function tests (PFTs) and cardiac catheterization data from recipients of successful heart transplants prior to and 1 year after transplantation. Thirty-eight patients met the inclusion criteria (median age, 52 years). The median duration of symptomatic CHF prior to transplantation was 22 months (range, 3 to 72 months). After transplantation, spirometry revealed an improvement in FEV1 from 75.8 +/- 3.5 to 99.1 +/- 2.8 percent of predicted and FVC from 81.3 +/- 3.7 to 101.6 +/- 3.0 percent of predicted (p < 0.001). The FEV1/FVC ratio remained unchanged at 80 percent. Nonsmokers and former smokers had similar improvements in spirometry after transplantation. The TLC improved from 91.1 +/- 3.3 to 105.5 +/- 2.9 percent of predicted (p < 0.001); this improvement was due to an increase in inspiratory capacity. Diffusing capacity for carbon monoxide was decreased before transplantation and showed a small decline after transplantation from 82.3 +/- 3.2 to 76.8 +/- 2.6 percent of predicted (p < 0.05). After correction of severe CHF by cardiac transplantation, normalization of FEV1, FVC, and TLC can be anticipated. Diffusing capacity, however, may actually decline after transplantation.

Adolescent↗
PubMed2000

Diffusion capacity and haemodynamics in primary and chronic thromboembolic pulmonary hypertension.

The transfer factor of the lung for carbon monoxide (TL,CO) is decreased in patients with pulmonary hypertension. The pulmonary membrane diffusion capacity (Dm) and pulmonary capillary blood volume (Vc), were studied to establish: 1) the relative contribution of the components of the transfer factor to the decrease in TL,CO; 2) whether differences exist between primary pulmonary hypertension (PPH) and chronic thromboembolic pulmonary hypertension (CTEPH); and 3) the relationship between these parameters and haemodynamic parameters. Dm and Vc were determined in 19 patients with PPH and in eight patients with CTEPH. The patients had been referred for consideration for lung transplantation. Haemodynamic parameters were assessed by heart catheterization. In the PPH group, Vc was reduced in 12 of 19 patients (mean+/-SD Vc 72+/-14% of the predicted value) and Dm in 17 of 19 patients (60+/-22% pred). In the CTEPH group, Vc was reduced in six of eight patients and Dm in seven of eight patients. The mean TL,CO Dm and Vc values were similar to those in the PPH group. The reduction in pulmonary membrane diffusion capacity was significantly greater than that in pulmonary capillary blood volume. No differences in pulmonary and cardiovascular functional values were found between the groups. Right atrial pressure showed a significant negative correlation with pulmonary capillary blood volume and an increased pulmonary vascular resistance was associated with a decrease in pulmonary membrane diffusion capacity. These results suggest pronounced functional impairment of the alveolocapillary membrane in these patients.

Adult↗
PubMed1994

Clinical evaluation of lymphocyte sub-populations and oxygen radical production in sarcoidosis and idiopathic pulmonary fibrosis.

The purpose of this study was to investigate the relationship between bronchoalveolar lavage (BAL)-derived parameters of interstitial lung disease and clinical and lung function parameters in 34 patients with sarcoidosis and 23 patients with idiopathic pulmonary fibrosis (IPF). BAL findings of healthy individuals served as controls. Cell content and differentiation of BAL fluid were determined. Oxygen radical (O2-) production of BAL cells and of blood polymorphonuclear (PMN) cells was measured. Phenotypes of lung and blood lymphocytes were determined by immunoperoxidase staining. In addition, lung function was assessed, chest X-rays were made and serum ACE was measured. Lymphocyte alveolitis in sarcoidosis was associated with increased alveolar macrophage (AM) O2- production (P < 0.025 vs. sarcoidosis with normal lymphocyte counts). Patients with extrapulmonary sarcoidosis had higher CD4/CD8 ratios in BAL (P < 0.025) and shorter disease duration (P < 0.01) than those with strictly pulmonary sarcoidosis. Disease duration in sarcoidosis correlated inversely with the number of BAL cells (r = -0.38, P < 0.05), the relative and absolute number of lymphocytes in BAL fluid (r = -0.34, P < 0.05 and r = -0.44, P < 0.01, respectively) and the percentage of CD4-positive cells and the CD4/CD8 ratio (r = -0.43, P < 0.05 and r = -0.48, P < 0.025, respectively). Although significant increases in O2- production by BAL cells were observed in both IPF and sarcoidosis, only in sarcoidosis was a higher AM O2- production associated with a significantly lower total lung capacity (r = -0.67, P < 0.005) and pulmonary diffusing capacity TLCO (r = -0.50, P < 0.05). In conclusion, our findings show that lung lymphocyte phenotypes differ among patients with pulmonary and extrapulmonary sarcoidosis and that O2- production is upregulated in active sarcoidosis. In addition, our findings suggest that different relationships between BAL data and lung function in patients with sarcoidosis and IPF may be explained by differences in disease duration. In IPF, disease duration is likely to be underestimated because of its insidious onset. In sarcoidosis, the presence of extrapulmonary symptoms, helpful to establish an early diagnosis, is associated with significant BAL lymphocytosis.

Adult↗
PubMed1984

The effects of minor and moderately severe accidental chest injuries on pulmonary function in man.

Pulmonary function has been measured at intervals after direct chest injuries of mild and moderate severity in 46 patients. Ventilatory capacity (e.g. FEV1) and vital capacity were reduced and the residual volume was increased. Total lung capacity and alveolar volume were also reduced and as a result total pulmonary diffusing capacity (transfer factor) was decreased, however, the remaining lung had a normal diffusion coefficient. Intercostal nerve block at the fracture site did not improve ventilatory capacity although marked pain relief was achieved. Recovery was slower in those patients not admitted to hospital than in the more seriously injured patients who were admitted. It is suggested that more attention should be paid to the outpatient follow-up of such patients, perhaps paying particular attention to physiotherapy.

Accidents↗
PubMed1997

Red cell distortion and conceptual basis of diffusing capacity estimates: finite element analysis.

To understand the effects of dynamic shape distortion of red blood cells (RBCs) as it develops under high-flow conditions on the standard physiological and morphometric methods of estimating pulmonary diffusing capacity, we computed the uptake of CO across a two-dimensional geometric capillary model containing a variable number of equally spaced RBCs. RBCs are circular or parachute shaped, with the same perimeter length. Total CO diffusing capacity (DLCO) and membrane diffusing capacity (DMCO) were calculated by a finite element method. DLCO calculated at two levels of alveolar PO2 were used to estimate DMCO by the Roughton-Forster (RF) technique. The same capillary model was subjected to morphometric analysis by the random linear intercept method to obtain morphometric estimates of DMCO. Results show that shape distortion of RBCs significantly reduces capillary diffusive gas uptake. Shape distortion exaggerates the conceptual errors inherent in the RF technique (J. Appl. Physiol. 79: 1039-1047, 1995); errors are exaggerated at a high capillary hematocrit. Shape distortion also introduces additional error in morphometric estimates of DMCO caused by a biased sampling distribution of random linear intercepts; errors are exaggerated at a low capillary hematocrit.

Algorithms↗
PubMed1998

Single-breath diffusing capacities for NO, CO and C18O2 in rabbits.

Nitric oxide (NO) has been introduced recently for studying alveolar-capillary gas transfer. Due to extremely fast reaction kinetics for the association of NO with haemoglobin, pulmonary NO uptake is expected to depend only on diffusion, whereas in the case of carbon monoxide (CO) or oxygen-labelled carbon dioxide (C18O2) the alveolar-capillary transfer is, in addition, known to depend on a blood uptake component. To provide further data for NO, CO and C18O2, we determined the pulmonary diffusing capacities (DL) for the indicator gases mentioned, performing single-breath manoeuvres on ten rabbits. The inspired gas mixtures contained 0.05% NO and/or 0. 2% CO or 1% C18O2 in nitrogen. Applying respiratory mass spectrometry to the expirates we obtained the following mean +/- SD values: DL,NO/DL,CO = 3.55 +/- 0.4, DL,C18O2/DL,NO = 6.0 +/- 0.6, DL, C18O2/DL,CO = 21.4 +/- 2.5. Graham's law predicts DL ratios of 1.9 for NO/CO, 12 for C18O2/NO, and 23 for C18O2/CO. Thus we equally underestimated the predicted DL ratios for C18O2/NO and CO/NO by a factor of approximately 0.5. From this, and by excluding significant interactions between the indicator gases and lung tissues, we conclude that the closest approximation of the diffusive component of DL is indeed obtained by using NO.

Animals↗
PubMed2002

Respiratory function in singleton and twin pregnancy.

OBJECTIVE: Singleton pregnancy causes important changes in respiratory function. The incidence of twin pregnancies is increasing, but it is not known whether affected women suffer greater respiratory compromise. The aim of this study was to determine if changes in respiratory function during pregnancy in healthy women were greater in those with a twin pregnancy compared with those with a singleton pregnancy. DESIGN: Cross sectional study. SETTING: London teaching hospital. POPULATION: Healthy pregnant women attending the antenatal clinic and ultrasound department. METHODS: A cross sectional study of respiratory function was performed in 68 women with twin pregnancies (17 examined in the first trimester, 35 second trimester, 16 third trimester) and 140 women with singleton pregnancies (28, 80, 40, respectively) and 22 non-pregnant women. Women were examined once between 7 and 40 weeks of gestation. Forced vital capacity, relaxed vital capacity, forced expiratory volume in 1 second (FEV1), peak flow, inspiratory capacity, functional residual capacity (FRC), expiratory reserve volume, pulmonary diffusing capacity and minute ventilation were measured. RESULTS: Both in twin and singleton pregnancies, the mean FRC and expiratory reserve ventilation of women studied in the third trimester and minute ventilation of women studied in each trimester differed significantly from that of the non-pregnant women. There were, however, no significant differences demonstrated in respiratory function between healthy women with twin as compared with singleton pregnancies. CONCLUSION: In healthy women, the extra demands of atwin compared with a singleton pregnancy do not compromise further the respiratory system.

Adult↗
PubMed1982

Pulmonary blood flow, diffusing, capacity and tissue volume by rebreathing: theory.

The determination of pulmonary capillary blood flow (Q), diffusing capacity (D) and tissue volume (Vtis) from rebreathing equilibration kinetics is studied on mathematical models. The validity of a continuously ventilated two-compartment model (model II) is analyzed with reference to a cyclically ventilated model (model III) and compared to a one-compartment model (model I). Use of model II leads to slight overestimation of Q and D, and to underestimation of Vtis whereas model I yields considerable underestimation of D, Q and Vtis. The following procedures are recommended: (1) Rebreathing data should be analyzed on the basis of model II. (2) Q and D should be calculated from the rate constant of fast (k1) and slow (k2) exponential component and extrapolated zero-time intercept of K2, based on end-expired gas fractions, of the gas under study (e.g. C2H2, CO). (3) Addition of an insoluble inert gas (e.g. He) is required only for Vtis. (4) Soluble inert gases with blood-gas partition coefficient (lambda) less than 1 (e.g. C2H2, CHC1F2) applied at low concentration should be used for determination of Q and Vtis. (5) A high rebreathing ventilation is recommended.

Blood Gas Analysis↗
PubMed1994

Cardiopulmonary adaptation to weightlessness.

The lung is profoundly affected by gravity. The absence of gravity (microgravity) removes the mechanical stresses acting on the lung paranchyma itself, resulting in a reduction in the deformation of the lung due to its own weight, and consequently altering the distribution of fresh gas ventilation within the lung. There are also changes in the mechanical forces acting on the rib cage and abdomen, which alters the manner in which the lung expands. The other way in which microgravity affects the lung is through the removal of the gravitationally induced hydrostatic gradients in vascular pressures, both within the lung itself, and within the entire body. The abolition of a pressure gradient within the pulmonary circulation would be expected to result in a greater degree of uniformity of blood flow within the lung, while the removal of the hydrostatic gradient within the body should result in an increase in venous return and intra-thoracic blood volume, with attendant changes in cardiac output, stroke volume, and pulmonary diffusing capacity. During the 9 day flight of Spacelab Life Sciences-1 (SLS-1) we collected pulmonary function test data on the crew of the mission. We compared the results obtained in microgravity with those obtained on the ground in both the standing and supine positions, preflight and in the week immediately following the mission. A number of the tests in the package were aimed at studying the anticipated changes in cardiopulmonary function, and we report those in this communication.

Adaptation, Physiological↗
PubMed1978

Training and oxygen conductance in the elderly. I. The respiratory system.

Static lung volumes, closing volumes and pulmonary diffusing capacity have been measured in a group of 19 subjects (9 M, 10 F) 60 - 76 years old, all volunteers for an exercise training program (nominal 4 hours per week for 11 weeks). Initial static lung volumes were larger than in some previous series, perhaps because our sample was health-conscious and mainly nonsmokers. Training produced no significant changes in any of the pulmonary variables tested, despite a 10% increase of maximum oxygen intake seen in those members of the group who progressed to intensive training (heart rate 145 - 155/min). This reflects the fact that oxygen transport depends more on blood transport than on the respiratory system.

Age Factors↗
PubMed1999

Angiotensin-converting enzyme inhibition restores the diffusing capacity for carbon monoxide in patients with chronic heart failure by improving the molecular diffusion across the alveolar capillary membrane.

Conductance of alveolar capillary membrane (DM) and capillary blood volume (VC) are the subcomponents of the pulmonary diffusing capacity for carbon monoxide (DLCO). In chronic heart failure, stress failure of the membrane provides a mechanism for reduced DM and subsequent impairment of DLCO. Angiotensin-converting enzyme inhibition improves DLCO in patients with chronic heart failure. This study was aimed at investigating which of the two subcomponents of DLCO is affected by angiotensin-converting enzyme inhibitors. Twenty-seven patients with NYHA class II to III chronic heart failure (group 1) and 13 age- and sex-matched normal subjects underwent pulmonary function testing with determination of DM and VC, while receiving placebo and 48 h and 1 and 2 months after starting enalapril treatment (10 mg twice daily). Nine similar patients (group 2) received isosorbide dinitrate (40 mg thrice daily) for a month then enalapril for another month, and underwent pulmonary function testing at 48 h and 1 month after starting treatments. Effects of angiotensin-converting enzyme inhibition in normal controls were not significant in the short- or mid-term. In group 1 patients, the only change observed at 48 h was a reduction in VC (probably due to a decrease in capillary pulmonary pressure). There was a marked increase in DM to a similar extent at 1 and 2 months, resulting in a significant improvement in DLCO despite a decrease in VC. In group 2 patients, nitrates failed to improve DLCO and DM, whereas enalapril was as effective as in group 1. These observations suggest a modulatory effect of angiotensin-converting enzyme inhibition on the membrane function which emerges gradually and persists over time and is probably dissociated from changes in pulmonary capillary pressure and VC. Chronic heart failure disturbs the alveolar capillary interface and increases gas diffusion resistance; angiotensin-converting enzyme inhibition restores the diffusive properties of the membrane and gas transfer, and protects the lung when the heart is failing.

Analysis of Variance↗
PubMed1987

A method for estimating contact time of red blood cells through lung capillary from O2 and CO2 concentrations in rebreathing air in man.

The gas exchange ratio (R) obtained from O2 and CO2 concentrations measured in rebreathing air usually shows a linear relation to the PCO2. By referring to this relation and the R which equals the Haldane effect coefficient and zero, the true- and oxygenated-venous PCO2 are obtained in addition to the alveolar PCO2. When these PCO2 are evaluated, the R-PCO2 line can also be computed theoretically from a numerical solution on the overall O2 and CO2 diffusions in the red blood cell. By comparing both the experimental and theoretical R-PCO2 lines with each other, we derived a contact time equation. Since the linear approximation of the R-PCO2 relation gave rise to an error in the contact time (tc), first a factor to correct the linearity of the R-PCO2 line was derived. Next, using these parameter values, tc was quantitatively determined from experimental data obtained during rebreathing in 5 normal subjects and it was compared with that estimated from the pulmonary diffusing capacity for CO in the same rebreathing experiment. When the extracellular HCO3- dehydration rate was taken to be 0.1 s in time constant, the tc, being ca. 0.7 and 0.4 s at rest and during exercise, respectively, showed good agreement with those obtained from the diffusing capacity for CO.

Capillaries↗
PubMed1978

Pulmonary involvement in systemic lupus erythematosus.

Several series have suggested that pulmonary function abnormalities are common in systemic lupus erythematosus. However, only isolated studies have attempted to relate these abnormalities to immunological aspects of the diseases. In the present study respiratory symptoms, pulmonary function tests, and immunological data were reviewed in 22 patients with systemic lupus erythematosus. Seventeen subjects had either clinical evidence or abnormalities of lung function suggestive of pulmonary involvement. A restrictive ventilatory defect or reduction in pulmonary diffusing capacity for carbon monoxide was demonstrated in 14 of the patients only 4 of whom were dyspnoeic. There was no correlation between pulmonary involvement, co-existent renal lupus, and immunological abnormality.

Adolescent↗
PubMed1987

Pulmonary development in growing guinea pigs exposed to chronic hypercapnia.

The role of lung stretch in causing pulmonary hyperplasia was studied in weanling male guinea pigs breathing air or 5% CO2 (in 22% O2, 73% N2) for 4 weeks. By the end of the exposure, oxygen consumptions were similar for both groups, but tidal volume and minute ventilation doubled in the hypercapnic group compared to controls. Arterial and venous blood gases reflected compensatory increases in plasma bicarbonate in animals breathing 5% CO2. The two groups did not differ in growth rate, lung volume or weight, alveolar surface area, anatomically estimated pulmonary diffusing capacity, or lung cellularity and protein content. Despite a chronic doubling of tidal volume during a peak growth period, hyperventilation did not stimulate pulmonary development, at least in normoxia and when oxygen consumption remained constant.

Animals↗