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At least 775 records · Page 43Linked to original sources
PubMed1994

[Lung manifestation of progressive systemic scleroderma. Computerized tomographic findings].

Progressive systemic scleroderma (PSS) is caused by generalized connective tissue disorder. The most frequent visceral manifestations are pulmonary and oesophageal involvement. Early detection of such visceral manifestations, which are sometimes life-limiting, is of paramount importance in any diagnostic procedures. The sensitivity of the methods differs and depends on the stage of the disease. Modified high-resolution computed tomographic scans (HRCT) were obtained in 28 patients with early forms of PSS and showed pulmonary involvement in 79% and signs of oesophageal involvement in 54%. HRCT is much more sensitive than chest radiography, lung scintigraphy and lung function tests even at an early stage of the disease. Classification of PSS should take account of the clinical type of sclerosis and of immunological and other parameters of prognostic importance.

Adult↗
PubMed2006

Scaling skeletal muscle function to mass in patients with moderate-to-severe COPD.

Skeletal muscle performance and muscle mass are commonly reduced in patients with advanced chronic obstructive pulmonary disease (COPD). It is currently unclear, however, whether negative changes in muscle structure and function are proportionately related to each other in these patients. In a cross-sectional study, 39 patients (post-bronchodilator FEV1=49.7+/-15.5% pred) and 17 controls were submitted to knee isokinetic dynamometry [peak torque (PT), isometric strength (IS), and total work (TW)] and dual energy X-ray absorptiometry for the evaluation of leg muscle mass (LMM). Muscle function (F) was normalised for LMM by using ratio standards (F.LMM-1), power function ratios (F.LMM-b, where b is usually not equal 1), and analysis of covariance (ANCOVA). Patients with COPD presented with reduced PT, IS, TW, and LMM as compared to controls: there were significant linear correlations among these variables in both groups (P<0.05). Ratio standards of PT.LMM-1 and TW.LMM-1 were, on average, 14% lower in patients than controls (P<0.01). The coefficients for allometric correction of IS and TW were significantly higher in patients as compared to controls (0.975 vs. 0.603 and 1.471 vs. 0.824, respectively, P<0.05), i.e. more LMM was needed to generate a given functional output in patients than normal subjects. In addition, adjusted means of muscle function variables by ANCOVA were 11-18% lower for patients than controls with LMM as the covariate (P<0.05). We conclude that factors other than simple atrophy (i.e. mass-independent mechanisms) might play a role in explaining the COPD-related skeletal muscle dysfunction.

Absorptiometry, Photon↗
PubMed1980

Systemic involvement and immunologic findings in patients presenting with Raynaud's phenomenon.

Systemic involvement and spectrum of autoantibodies were evaluated in 91 patients presenting with Raynaud's phenomenon. Decreased pulmonary diffusing capacity was observed in 23 percent, esophageal hypomotility in 14 percent and renal involvement in 5 percent of the patients, all without clinical symptoms. Arthralgia or a history of arthritis was present in 27 percent and skin abnormalities in 30 percent. Extent of systemic involvement was correlated with the severity of Raynaud's phenomenon, as measured by photoelectric plethysmography (r = 0.38; p < 0.01). In addition, both the variety of different autoantibodies in the serum of individual patients and the titer of antinuclear antibodies were positively correlated with the number of affected organ systems (r = 0.63; p < 0.01 and r = 0.65; p < 0.01, respectively). Raynaud's phenomenon is an important clinical sign of asymptomatic systemic disease. Measurements of its severity and serologic parameters are helpful in predicting the extent of systemic involvement.

Adult↗
PubMed1977

Theoretical analysis of independent VA and Q inequalities upon pulmonary gas exchange.

A 10-compartment model is used to study the effects independent regional inequalities in ventilation (VA) and blood flow (Q) upon overall gas exchange in the lung. For the particular distribution considered, it is demonstrated that unequal ventilation always gives rise to a greater degree of hypoxaemia than unequal blood flow, and that these differences become more marked when minute volume is high. In contrast, hypercarbia is more pronounced in situations where blood flow is unequal; however, the differences diminish with increases in minute volume. Increases in cardiac output are found to have a lesser effect upon the gas exchange process. The reasons for the findings are explained by reference to the gas dissociation curves, the spread of VA/Q ratios, and the weighting influence of regional blood flow. The apparent disparity of the present results with those obtained by assuming a log normal distribution of the respiratory parameters (VA and Q) are reconciled.

Blood Gas Analysis↗
PubMed1982

A morphometric analysis of the lung of a species of bat.

The lungs of five adult Epauleted Fruit-bats (Epomophorus wahlbergi) of mean body weight 96 g were analysed morphometrically. The lung volume per unit body weight was 0.043 cm3/g, the surface area of the tissue barrier (i.e., the effective alveolar surface area) component of the blood-gas pathway per unit body weight was 138 cm2/g, and the surface density of the tissue barrier (surface area of the tissue barrier per unit volume of parenchyma) was 121 mm2/mm3. The harmonic mean thickness of the tissue barrier was between 0.267 and 0.349 micron. The morphometric pulmonary diffusing capacity per unit body weight (DLO2/W) was 0.02 ml O2 per min per mm Hg per g. These values are compared with those of shrews and birds. It is suggested that in bats enlargement of the lungs, small subdivisions of the air spaces, and a thin blood-gas barrier, could be linked with previously reported circulatory adaptations to account for the high oxygen consumption during flight.

Animals↗
PubMed1988

Estimating steady-state DLO2 with nonlinear dissociation curves and VA/Q inequality.

A DLO2 estimate which accounts for the nonlinearity of the oxygen dissociation curve using the Kelman blood gas routines is presented here. The simultaneous differential equations that describe O2 and CO2 diffusion between alveolar gas and pulmonary capillary blood in lung compartments with different VA/Q ratios were solved numerically with a Runge-Kutta algorithm. These integrated estimates were compared to DLO2 estimates that assume the oxygen dissociation curve is linear. In 140 gas exchange data sets from 18 healthy male subjects previously collected at rest and during exercise it was found that DLO2 estimates based on linear dissociation curves exceeded integrated DLO2 estimates by 14, 31, and 55 percent when the PIO2 was 80, 100, and 148 Torr, respectively. We conclude that the linear approximation is accurate when PIO2 is less than 100 Torr but that comparisons of DLO2 estimates at different levels of inspired oxygen must allow for the difference in curvature of the oxygen dissociation curve as a function of PIO2.

Algorithms↗
PubMed1989

Helium and SF6 washout from dog lungs during high-frequency ventilation.

Simultaneous washout of He and SF6 was studied in anesthetized paralyzed dogs (mean body weight 19 kg) subjected to high-frequency ventilation at varying frequencies (10-40 Hz), stroke volumes (20-40 ml), lung volumes (0.8-1.2 L) and fresh gas flow rates (7-13 L/min). The washout curves could be analyzed into three exponential components for both test gases. The rate constants of the intermediate and slow components were slightly but significantly higher for He than for SF6 while the fast component was the same for the two test gases. The data were analyzed on the basis of a series lung model with a dead space compartment and two serially arranged alveolar compartments. The He/SF6 ratio of the effective conductances for gas transfer between the alveolar compartments averaged 1.15 +/- 0.08 (SD). Since this ratio is much closer to unity, predicted for convective transport, than 6 to 7, predicted for diffusive transport, it is concluded that during high-frequency ventilation gas transport in peripheral airways occurs by both convection and diffusion, convection being quantitatively more important.

Animals↗