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PubMed1989

An allometric study of pulmonary morphometric parameters in birds, with mammalian comparisons.

Comprehensive pulmonary morphometric data from 42 species of birds representing ten orders were compared with those of other vertebrates, especially mammals, relating the comparisons to the varying biological needs of these avian taxa. The total lung volume was strongly correlated with body mass. The volume density of the exchange tissue was lowest in the charadriiform and anseriform species and highest in the piciform, cuculiform and passeriform species. The surface area of the blood-gas (tissue) barrier, the volume of the pulmonary capillary blood and the total morphometric pulmonary diffusing capacity were all strongly correlated with body mass. The harmonic mean thickness of both the blood-gas (tissue) barrier and the plasma layer were weakly correlated with body mass. The mass-specific surface area of the blood-gas (tissue) barrier (surface area per gram body mass) and the surface density of the blood-gas (tissue) barrier (i.e. its surface area per unit volume of exchange tissue) were inversely correlated (though weakly) with body mass. The passeriform species exhibited outstanding pulmonary morphometric adaptations leading to a high specific total diffusing capacity per gram body mass, consistent with the comparatively small size and energetic mode of life which typify passeriform birds. The relatively inactive, ground-dwelling domestic fowl (Gallus gallus) had the lowest pulmonary diffusing capacity per gram body mass. The specific total lung volume is about 27% smaller in birds than in mammals but the specific surface area of the blood-gas (tissue) barrier is about 15% greater in birds. The ratio of the surface area of the tissue barrier to the volume of the exchange tissue was also much greater in the birds (170-305%). The harmonic mean thickness of the tissue barrier was 56-67% less in the birds, but that of the plasma layer was about 66% greater in the birds. The pulmonary capillary blood volume was also greater (22%) in the birds. Except for the thickness of the plasma layer, these morphometric parameters all favour the gas exchange capacity of birds. Consequently, the total specific mean morphometric pulmonary diffusing capacity for oxygen was estimated to be about 22% greater in birds than in mammals of similar body mass. This estimate was obtained by employing oxygen permeation constants for mammalian tissue, plasma and erythrocytes, as avian constants were not then available.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1994

An 8-year follow-up study of pulmonary function in patients with rheumatoid arthritis.

To evaluate longitudinal alterations in pulmonary function, 63 patients suffering from rheumatoid arthritis (RA) with previously reported reduced pulmonary diffusing capacity were re-examined in an 8-year follow-up study. Cross-sectional examination revealed normal values for vital capacity (VC), forced expiratory volume in 1 s (FEV1) and diffusing capacity per litre alveolar volume (KCO). Total diffusing capacity (DLCO; P < 0.0001), maximal expiratory flow at 75% of expired VC (MEF75; P < 0.0001) and MEF50 (P < 0.01) were decreased. Longitudinal evaluation revealed unchanged MEF50, MEF75 and FEV1, whereas increases in DLCO (P < 0.0001) and KCO (P < 0.0001) and a decrease in VC (P < 0.05) were found. The longitudinal changes in diffusing capacity were unrelated to patient age, disease duration, disease activity in the study period or pulmonary function at the first examination. Thus, in patients suffering from RA, the most prominent functional pulmonary abnormality, decreased diffusing capacity, appeared to improve in the course of time, despite a slight decrease in VC and continued articular disease activity.

Adult↗
PubMed1988

Effects of unilateral pleural symphysis on respiratory system mechanics and gas exchange in anesthetized dogs.

Lateral thoracotomy with pleural abrasion and application of talc was performed on 8 adult beagle dogs. The dogs had no effusion detectable on roentgenogram at the time of study, and obliteration of the pleural space was later confirmed by autopsy. With the dogs under pentobarbital anesthesia, lung mechanics and gas exchange were studied before and 5 wk after surgery. Total lung capacity decreased to 78% of control value (p less than 0.05). After the operation, pressure-volume curves of the respiratory system were shifted down, along with significantly decreased compliance. Maximal flow at constant lung volume was not significantly increased. Arterial O2 and CO2 tensions were not significantly different. Rebreathing DLCO normalized for lung volume was unchanged. The slope of phase III of a single-breath nitrogen test was increased (p less than 0.05) after surgery. Unilateral surgical obliteration of the pleural space results in a pure restrictive pattern. It does not affect the gas exchange surface. The increase in the slope of phase III is suggestive of a nonhomogeneous distribution of ventilation.

Anesthesia↗
PubMed1991

Effect of milk ingestion on pulmonary function in healthy and asthmatic subjects.

Since Maimonides, it has been common in folk medicine to proscribe milk for asthmatics because its putative stimulation of mucus production can exacerbate asthma symptoms. A literature review, however, failed to reveal any data supporting this notion. We, therefore, compared the effects of ingesting 16 oz. of whole milk (16 g lipid), skim milk (2 g lipid), and water (each on a separate day) on: (1) forced expiratory volume in 1 second (FEV1), (2) forced expiratory flow at 50% of vital capacity (V50), and (3) pulmonary diffusing capacity (DLCO) in 11 asthmatic and 10 nonasthmatic subjects. Measurements were taken at 30 minute intervals for 3 hours. The two milk types did not significantly change FEV1 or V50 in either group, indicating that the amount ingested did not change airway resistance sufficiently to alter airflow parameters. In the asthmatic group, however, DLCO decreased progressively over the 3 hours by 6.8 +/- 1.4% (mean +/- SE) per hour after whole milk (maximum reduction = 21 +/- 1.4%) but not after water or skim milk. In the nonasthmatic group, no significant effects were observed on DLCO after any of the liquids. These data suggest that milk lipids can disturb gas exchange in asthmatic patients.

Adult↗
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↗
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↗