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PubMedDate not supplied

Efficacy and effects on pulmonary function tests of weekly 600 mg aerosol pentamidine as prophylaxis against Pneumocystis carinii pneumonia.

A prospective study was designed to evaluate the efficacy and effects on pulmonary function tests of weekly 600 mg aerosolised pentamidine as prophylaxis against Pneumocystis carinii pneumonia (PCP) amongst two groups of patients infected with the human immunodeficiency virus. Group 1 (primary prophylaxis) consisted of patients with either diseases indicative of AIDS other than PCP or whose absolute CD4 positive lymphocyte count was below 200/mm3, and Group 2 (secondary prophylaxis) comprised patients with previous proven episodes of PCP. Fifty-five patients (30-Group 1, 25-Group 2) were studied over a period of 36 months, and no patients reached a study end point of either relapse or death due to PCP after a mean duration of treatment of 14.9 months (range 9-36 months). There were no significant differences between the pulmonary function tests (forced expiratory volume in the first second, forced vital capacity and carbon monoxide diffusion capacity) performed at the start and end of the study on both groups of surviving patients. Ten patients (18%) reported coughing and eight patients (15%) were documented to have bronchoconstriction, which was found to be preventable by prior administration of disodiumcromoglycate. The results showed that weekly 600 mg aerosolised pentamidine is effective and well tolerated for primary and secondary prophylaxis against PCP without additional adverse effects. Further prospective randomized trials are needed to determine whether doses higher than the current recommended 300 mg monthly dosage of aerosolised pentamidine provide more efficacy before such an alternative prophylactic treatment is generally adopted for patients who cannot tolerate other systemic agents.

Administration, Inhalation↗
PubMed2006

Model analysis on alveolar-capillary O2 equilibration during exercise.

The present article was aimed at determining the alveolar-capillary PO2 difference (deltaP(AcO2)) during exercise. The working hypothesis was that values of the pulmonary NO diffusing capacity can be used to calculate (deltaP(AcO2)) data on the basis of well-known laws of pulmonary gas exchange. For this purpose, we analysed the pertinent data of three studies performed on 35 healthy, non-athletic non-smokers of similar age at seven different exercise intensities. Calculated mean values of alveolar-capillary PO2 difference aggravated from deltaP(AcO2) at rest to (deltaP(AcO2))=18 mmHg at a performance capacity amounting to 90% of the maximum level. Regression analysis revealed (deltaP(AcO2))=0.31* (V O2/V O2 max)2 at a very high significance level (n=7, r=0.999, P<0.0000082). Due to the non-linear increase of (deltaP(AcO2)) with inclining O(2) consumption, our model analysis confirms the opinion that pulmonary diffusion decreasingly determines maximal aerobic power.

Exercise↗
PubMed1998

Single-breath CO diffusing capacity influenced by initial alveolar partial pressure of CO.

The purpose of this study was to assess the influence of incorrect determinations of the initial alveolar partial pressure of carbon monoxide (CO) at the beginning of breath holding (PIACO) on the pulmonary CO diffusing capacity of the lung (DLCO). Single-breath maneuvers were performed on 14 anesthetized and artificially ventilated rabbits, using 0.2% CO in nitrogen as the indicator gas mixture. Inflation and deflation procedures were carried out in an identical manner on each animal, with inflation always starting from residual volume. End-tidal partial pressure of CO was determined by respiratory mass spectrometry and was used to calculate DLCO values with the application of the three-equation (method 1), as well as the conventional (method 2), solution. In each rabbit, method 2 caused DLCO values to be overestimated when compared with method 1, and this overestimation decreased with increasing time intervals of CO uptake. Because we were able to recalculate this deviation using PIACO values that were obtained by taking the diffusive removal of CO during inflation into account, we concluded that errors in estimating PIACO by applying method 2 significantly contribute to the discrepancy between both methods.

Animals↗
PubMed1998

Correction of single-breath helium lung volumes in patients with airflow obstruction.

STUDY OBJECTIVE: To determine whether alveolar volume (V(A)) measured during the single-breath diffusing capacity for carbon monoxide (DCO) can be used as a substitute measure for the multiple-breath total lung capacity (TLC) in subjects with and without airways obstruction. DESIGN: Retrospective review of pulmonary function test (PFT) results. SETTING: Pulmonary function laboratories at the Johns Hopkins Hospital (JHH) and the Johns Hopkins Asthma and Allergy Center (HAAC). PARTICIPANTS: Patients referred for spirometry, helium lung volumes, and Dco during a single visit between November 1993 and November 1996. RESULTS: JHAAC patients (n=2,477) were used to assess the relationship between V(A) and TLC. In patients with an FEV1/FVC > or = 0.70, there was good agreement between V(A) and TLC (V(A)/TLC=0.97 to 0.99). However, in patients with an FEV1/FVC <0.70, V(A) systematically underestimated TLC (V(A)/TLC=0.67 to 0.94). The degree of underestimation was related to the severity of airflow obstruction. To predict TLC using V(A) a regression equation was used to "correct" V(A) for the severity of obstruction. This equation was used to predict the multiple-breath TLC for JHH patients (n=2,892). Patients with an FEV1/FVC > or = 0.70 showed a high degree of correlation between V(A) and TLC (Pearson's correlation coefficient [r]=0.96 to 0.99; p<0.05). After adjusting for the severity of airflow obstruction, patients with an FEV1/FVC in the range of 0.40 to 0.70 also had a strong correlation between the corrected V(A) and the multiple-breath TLC (r=0.83 to 0.94; p<0.05). CONCLUSIONS: V(A) accurately predicts TLC in patients with mild or no airflow obstruction. For patients with moderate to severe obstruction, correcting V(A) for the severity of obstruction improves the accuracy of this relatively simple and rapid technique for measuring TLC.

Female↗
PubMed1992

[Acute alveolitis due to mesalazine].

A 66-year-old male developed lymphocytic alveolitis with bronchiolitis after 3 month's treatment with mesalazin for ulcerative colitis. The patient's symptoms disappeared after halting mesalazin and increasing the steroid dose, the reduced diffusing capacity ameliorated and the thoracic X-ray normalized. The question whether this was a case of pulmonary involvement in inflammatory bowel disease or a drug side effect.

Aged↗
PubMed1984

Inspired volume dependence of the slope of the alveolar plateau.

Two series of experiments were performed in nine healthy subjects. In series I, 96 single breath tests were performed in two subjects. The inspired gas contained 90% O2, 5% He and 5% SF6 and the slope of the alveolar plateau for N2, He and SF6 was computed. The following experimental conditions were considered variable: inspired volume with preinspiratory lung volume equal to residual volume or functional residual capacity (FRC), both with and without 10 sec breath-holding. In series II, each of the other 7 subjects performed 12 single breath N2 tests in which the subject inspired both 1 L and an inspiratory capacity (IC) of O2 from FRC with without 10 sec breath-holding. The main experimental observation is that without breath-holding the absolute value of the slope of the alveolar plateau is larger for 1 L inspiration than for an IC inspiration, whereas this volume dependence was smaller after 10 sec of breath-holding. Based on Milic-Emili model of the lung and on simulations of a multibranch point model of the acinus we concluded that, in so far as these models adequately describe gas distribution in the lung, intraregional parallel units presenting a sequential convective flow play an important role in the genesis of the alveolar plateau.

Adult↗
PubMed2005

Pattern of diffusion disturbance related to clinical diagnosis: The K(CO) has no diagnostic value next to the DL(CO).

AIM OF THE STUDY: The diffusion capacity of the lung for carbon monoxide (DL(CO)) is an important tool in the diagnosis and follow-up of patients with pulmonary diseases. In case of a decreased DL(CO) the K(CO), defined as DL(CO)/V(A) (V(A) is alveolar volume), can differentiate between normal alveolocapillary membrane (normal K(CO)) and abnormal alveolocapillary membrane (low K(CO)). The latter category consists of decreased surface of the membrane, increased thickness or decreased perfusion of ventilated alveoli. The V(A)/TLC (TLC is total lung capacity determined by whole body plethysmography) can partially differentiate between these categories. The aim of this study was to investigate the diagnostic value of the specific diffusion disturbances, which can be constructed by combining the DL(CO), K(CO) and V(A)/TLC. METHODS: In 460 patients the diagnosis made by clinicians were fitted into five diagnostic categories: asthma, chronic obstructive pulmonary disease (COPD), treatment effects of haematologic malignancies, heart failure and diffuse parenchymal lung diseases (DPLD). These categories were linked to the pattern of diffusion disturbance. RESULTS: Almost all patients with asthma have a normal DL(CO), most patients in the other groups do not have the expected pattern of diffusion disturbance, especially in the group with DPLD a bad match is observed. CONCLUSION: In this study the pattern of diffusion disturbance is of limited use in establishing a diagnosis. The use of the K(CO) next to the DL(CO) has no additional diagnostic value. Regional ventilation-perfusion inequality probably forms an important underlying mechanism of decreased DL(CO).

Adolescent↗
PubMed1985

Radiologic findings in farmer's lung. Prognosis and correlation to lung function.

We classified the radiologic findings of 93 patients with acute or subacute farmer's lung (FL) disease by type and severity of the change in chest x-ray film. Acute radiologic changes, further divided as nodular, ground-glass, or striated patchy opacities, were found in 78/93 patients at the first evaluation; 11 showed chronic changes (radiologic "fibrosis"), which persisted unchanged throughout the follow-up period; and four initially had a normal chest x-ray film. Patients were followed up 23 months on an average. The more severe the radiologic change at the first evaluation, the more impaired the diffusing capacity (Dsb). Severe radiologic changes disappeared more slowly than the less severe ones. The differences in the initial pulmonary function values between the two groups disappeared during the follow-up. The type of acute change did not predict the recovery of respiratory performance. Treatment with oral corticosteroids did not affect the outcome of lung function or appearance of chronic changes, although corticosteroids seemed to hasten the disappearance of diffuse opacities. At the final evaluation, the chest x-ray film was normal in 55/93 patients. Chronic changes were detected in 38 patients. Severe radiologic appearance and striated patchy opacities predisposed to development of chronic changes.

Adrenal Cortex Hormones↗
PubMed1991

A morphometric study of the lungs of different sized bats: correlations between structure and function of the chiropteran lung.

1. The lungs of four species of bats, Phyllostomus hastatus (PH, mean body mass, 98 g), Pteropus lylei (PL, 456 g), Pteropus alecto (PA, 667 g), and Pteropus poliocephalus (PP, 928 g) were analysed by morphometric methods. These data increase fivefold the range of body masses for which bat lung data are available, and allow more representative allometric equations to be formulated for bats. 2. Lung volume ranged from 4.9 cm3 for PH to 39 cm3 for PP. The volume density of the lung parenchyma (i.e. the volume proportion of the parenchyma in the lung) ranged from 94% in PP to 89% in PH. Of the components of the parenchyma, the alveoli composed 89% and the blood capillaries about 5%. 3. The surface area of the alveoli exceeded that of the blood-gas (tissue) barrier and that of the capillary endothelium whereas the surface area of the red blood cells as well as that of the capillary endothelium was greater than that of the tissue barrier. PH had the thinnest tissue barrier (0.1204 microns) and PP had the thickest (0.3033 microns). 4. The body mass specific volume of the lung, that of the volume of pulmonary capillary blood, the surface area of the blood-gas (tissue) barrier, the diffusing capacity of the tissue barrier, and the total morphometric pulmonary diffusing capacity in PH all substantially exceeded the corresponding values of the pteropid species (i.e. PL, PA and PP). This conforms with the smaller body mass and hence higher unit mass oxygen consumption of PH, a feature reflected in the functionally superior gas exchange performance of its lungs. 5. Morphometrically, the lungs of different species of bats exhibit remarkable differences which cannot always be correlated with body mass, mode of flight and phylogeny. Conclusive explanations of these pulmonary structural disparities in different species of bats must await additional physiological and flight biomechanical studies. 6. While the slope, the scaling factor (b), of the allometric equation fitted to bat lung volume data (b = 0.82) exceeds the value for flight VO2max (b = 0.70), those for the surface area of the blood-gas (tissue) barrier (b = 0.74), the pulmonary capillary blood volume (b = 0.74), and the total morphometric lung diffusing capacity for oxygen (b = 0.69) all correspond closely to the VO2max value. 7. Allometric comparisons of the morphometric pulmonary parameters of bats, birds and non-flying mammals reveal that superiority of the bat lung over that of the non-flying mammal.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗