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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↗
PubMed1993

Exercise-induced hypoxemia in heart transplant recipients.

OBJECTIVES: The purpose of this study was to determine whether heart transplantation has an adverse effect on pulmonary diffusion and to investigate the potentially deleterious effects of impaired pulmonary diffusion on arterial blood gas dynamics during exercise in heart transplant recipients. BACKGROUND: Abnormal pulmonary diffusing capacity is reported in patients after orthotopic heart transplantation. Abnormal diffusion may be caused by cyclosporine or by the persistence of preexisting conditions known to adversely affect diffusion, such as congestive heart failure and chronic obstructive pulmonary disease. METHODS: Eleven patients (mean age 50 +/- 14 years) performed pulmonary function tests 3 +/- 1 months before and 18 +/- 12 (mean +/- SD) months after heart transplantation. Transplant patients were assigned to groups with diffusion > 70% (n = 5) or diffusion < 70% of predicted values (n = 5). The control group and both subsets of patients performed 10 min of cycle exercise at 40% and 70% of peak power output. Arterial blood gases were drawn every 30 s during the 1st 5 min and at 6, 8 and 10 min. RESULTS: Significant improvements in forced vital capacity (17.4%), forced expiratory volume in 1 s (11.7%) and diffusion capacity (6.6%) occurred in the patients; however, posttransplantation vital capacity, forced expiratory volume and diffusion were lower (p < or = 0.05) compared with values in 11 matched control subjects. Changes in blood gases were similar among groups at 40% of peak power output. At 70% of peak power output, arterial blood gases and pH were significantly (p < or = 0.05) lower in transplant patients with low diffusion (arterial oxygen pressure 15 to 38 mm Hg below baseline) than in patients with normal diffusion and control subjects. Cardiac index did not differ (p > or = 0.05) between transplant patients with normal and low diffusion at rest or during exercise. Posttransplantation mean pulmonary artery pressure was significantly related to exercise-induced hypoxemia (r = 0.71; p = 0.03). CONCLUSIONS: Abnormal pulmonary diffusion observed in patients before heart transplantation persists after transplantation with or without restrictive or obstructive ventilatory defects. Heart transplant recipients experience exercise-induced hypoxemia when diffusion at rest is < 70% of predicted. Our data also suggest that abnormal pulmonary gas exchange possibly contributes to diminished peak oxygen consumption in some heart transplant recipients; however, direct testing of this hypothesis was beyond the scope of the present study. This possibility needs to be investigated further.

Adult↗
PubMed1978

Pulmonary vascular effects of fat emulsion infusion in unanesthetized sheep. Prevention by indomethacin.

Pulmonary diffusing capacity and arterial blood Po(2) decrease in humans when 10% fat emulsion is infused. To study its effects on the pulmonary circulation and lung fluid balance, we infused 0.25 g/kg x h of a 10% fat emulsion (Intralipid, Cutter Laboratories, Inc., Berkeley, Calif.) into an awake sheep lung lymph preparation. The emulsion caused a sustained increase in pulmonary artery pressure to approximately twice base line with little change in left atrial pressure. Pa(O2) decreased an average 13 torr and lung lymph flow increased two- to threefold. Lymph/plasma total protein concentration fell as lymph flow increased; the magnitude of the lymph/plasma protein decrease was similar to that reported previously when lung vascular pressures were mechanically elevated. Heparin infusion (loading dose = 4,000 U, maintenance dose = 2,000 U/h) cleared the serum of triglycerides but did not alter the response to fat emulsion. Indomethacin infusion (loading dose = 5 mg/kg, maintenance dose = 3 mg/kg x h) blocked the rise in pulmonary artery pressure, the increase in lung lymph flow, and the fall in Pa(O2). Neither extravascular lung water nor [(14)C]urea lung vascular permeability surface area products were altered by fat emulsion infusion. We conclude that fat emulsion infusion in sheep increases lung microvascular filtration by increasing vascular pressures, but has no effect on vascular permeability. Since the effects are blocked by indomethacin, they may be prostaglandin mediated.

Animals↗
PubMed1991

[CO diffusing capacity during continuous negative extra-thoracic pressure].

Eight healthy males were studied to compare CO diffusing capacity (DLCO) during spontaneous breathing with that during continuous negative extra-thoracic pressure (CNETP). Mean DLCO was 33.0 +/- 5.1 ml.min-1.mmHg-1 during spontaneous breathing and 33.5 +/- 4.5 ml.min-1.mmHg-1 during CNETP with an end-expiratory negative extra-thoracic pressure (EENETP) of -20 cmH2O, and there was no significant difference between them (P less than 0.05). Pulmonary capillary blood volume, which was measured only in a male, was 76.7 ml during spontaneous breathing and 80.5 ml during CNETP. This change dose not seem to be significant. The results suggest that the effect of pulmonary diffusing capacity changes during EENETP on improvement of oxygenation may not be significant.

Adult↗
PubMed1980

Alveolar-capillary equilibration kinetics of 13CO2 in human lungs studied by rebreathing.

Blood/gas equilibration of CO2 in lungs was studied in man by a rebreathing technique, in which the rate of uptake of the stable isotope 13CO2 in low concentration (inspired concentration about 0.07%) was measured at blood/gas equilibrium of the abundant CO2 isotope. The results were expressed in terms of overall conductance for alveolar gas-pulmonary blood equilibration (DCO2, pulmonary diffusing capacity for CO2). The following mean values of DCO2 were found in 3 healthy young men (in mmol . min-1 . Torr-1): rest, 8.0; during exercise (75 Watts), 13.7. Comparison with DO2 measured by rebreathing in the same conditions suggests equilibration of the CO2/HCO3(-)/H+ system in blood, rather than diffusion of CO2, as the limiting process in capillary/alveolar CO2 transfer. The term 'equilibration capacity' is thus suggested for DCO2. Calculations based on the experimental results show that the overall limitation of pulmonary CO2 exchange function resulting from this finite DCO2 is slight at rest, but of considerable extent in heavy exercise.

Carbon Dioxide↗
PubMed2002

Does haemorheology explain the paradox of hypoxemia during exercise in elite athletes or thoroughbred horses?

Exercise-induced arterial hypoxemia (EIAH), i.e., a significant drop of O2 arterial partial pressure during sea level exercise, has been shown in both aerobically trained athletes and athletic animal species. The mechanisms potentially involved include ventilation/perfusion inequality and/or pulmonary diffusing capacity limitation. In thoroughbred horses, EIAH is going with pulmonary haemorrhage (EIPH). Stress failure of pulmonary capillaries leading to diffusion limitation has been proposed. Indeed, during intense exercise, the increased cardiac output and blood viscosity combine to rise capillary wall stress. Blood rheology may participate to the increase of VA/Q mismatch and capillary wall stress. High level of hematocrit (Hct) are known to alter blood flow distribution and rise shear stress in pulmonary capillaries. Any change in red blood cells (RBC) deformability may lead to aggregation at low shear rate, in post capillary veinules. There are contrasting data regarding the effects of blood rheology on EIPH in horses, however the large augmentation of hematocrit during exercise may cause vessel wall stress. In humans, greatest increase in hematocrit may participate to EIAH as well as RBC deformability. Today there is no consensus opinion and further studies of blood rheology in athletes is a field of interest.

Animals↗
PubMed1975

Diffusing capacity, membrane diffusing capacity, capillary blood volume, pulmonary tissue volume, and cardiac output measured by a rebreathing technique.

A rebreathing method for estimating diffusing capacity, membrane diffusing capacity, pulmonary capillary blood volume, pulmonary capillary blood flow, and pulmonary tissue volume consists of rebreathing into a bag for 15 sec while acetylene, (18O)-carbon monoxide, oxygen, and helium are continuously sampled by a mass spectrometer. Because the masses of carbon monoxide and nitrogen are nearly identical at 28, it was necessary to use a stable isotope, C18O, to distinguish this gas with the mass spectrometer. Comparison of the pulmonary capillary blood flow by the rebreathing technique with the simultaneously obtained indicator dilution measurement in anesthetized dogs revealed good agreement. Estimations of pulmonary tissue volume appeared to be quite reproducible and consistent; the values tended to be somewhat smaller and less variable among normal subjects than reported by other investigators. After subtraction of capillary blood volume, tissue volume was 311 plus or minus 73 ml at rest and increased significantly to 352 plus or minus 61 ml at 75 watts of exercise. Pulmonary tissue volume in dogs using the rebreathing method averaged 9.2 ml per kg of body weight, a mean comparable to previously reported estimates using the ether plethysmographic method. The slope of pulmonary capillary blood flow (cardiac output in normal subjects) as a function of oxygen consumption during exercise in normal subjects of 0.0060 times oxygen consumption in milliliter per min was identical to published values. The rebreathing technique provides a rapid, reliable, noninvasive method for estimating pulmonary hemodynamic parameters.

Acetylene↗
PubMed1991

Predictors of survival in systemic sclerosis (scleroderma).

We conducted followup of 264 patients with definite systemic sclerosis (SSc) who were entered into the multicenter Scleroderma Criteria Cooperative Study (SCCS) during 1973-1977. At the end of the study (average 5.2 years of followup), 38% were known to be alive, 50% were dead (68% of these deaths definitely related to SSc), and 12% were lost to followup. Survival analyses of 484 demographic, clinical, and laboratory items recorded at entry into the SCCS (within 2 years of physician diagnosis of SSc) were performed. Survival declined linearly, and the cumulative survival rate was less than 80% at 2 years, 50% at 8.5 years, and 30% at 12 years after entry. Analysis using combinations of entry variables identifying organ system involvement confirmed that renal, cardiac, pulmonary, and gastrointestinal involvement in SSc predicted reduced survival; however, data on organ system involvement at study entry could not be used to consistently predict which organ system would ultimately be involved as the primary cause of death. By survival tree analysis, the individual entry variables best predicting reduced survival included older age (greater than 64 years), reduced renal function (blood urea nitrogen greater than 16 mg/dl), anemia (hemoglobin less than or equal to 11 gm/dl), reduced pulmonary diffusing capacity for carbon monoxide (less than or equal to 50% of predicted), reduced total serum protein level (less than or equal to 6 gm/dl), and reduced pulmonary reserve (forced vital capacity less than 80% with hemoglobin greater than 14 gm/dl or forced vital capacity less than 65% with hemoglobin less than or equal to 14 gm/dl). Cox proportional hazards model analysis confirmed these results. Different combinations of variables led to markedly different survival rates. The poorest prospects for survival were in patients with SSc who were less than or equal to 64 years old with a hemoglobin level less than or equal to 11 gm/dl, and in those greater than 64 years old with a blood urea nitrogen level greater than 16 mg/dl. These results may be useful in predicting individual patients at risk for shortened survival.

Age Factors↗
PubMed1994

A modified photo- and magnetoacoustic multigas analyzer applied in gas exchange measurements.

The feasibility of replacing a conventional mass spectrometer (MS) with a specially modified multicomponent (O2, CO2, Freon 22, and SF6) acoustic infrared and paramagnetic (IR/PM) gas analyzer in inert gas-rebreathing and metabolic gas exchange measurements has been investigated. Rebreathing variables were determined simultaneously with the MS and IR/PM analyzers in duplicate measurements at rest and during submaximal exercise in 10 subjects. The differences (means +/- SD, IR/PM - MS) were 0.028 +/- 0.048 liters [functional residual capacity (FRC)], 0.18 +/- 0.38 l/min [cardiac output (Qc)], -0.006 +/- 0.030 l/min [O2 consumption (VO2)], and -33 +/- 108 ml [combined lung tissue and capillary blood volume (Vti,c)]. The coefficients of variation on repeated estimates were 5.8% (FRC), 5.4% (Qc), 6.2% (VO2), and 17% (Vti,c) with the IR/PM analyzer and 5.9% (FRC), 4.2% (Qc), 5.0% (VO2), and 9.8% (Vti,c) with the MS. The differences (IR/PM - MS) obtained in mixed-expirate measurements were -0.006 +/- 0.020 l/min (VO2) and 0.020 +/- 0.021 l/min (CO2 production). Breath-by-breath estimates of VO2 and CO2 production with the IR/PM analyzer were, on average, 2.4 and 4.4% higher than the MS estimates, respectively. Our results demonstrate that the IR/PM gas analyzer, when appropriately modified, can substitute for a complex MS in a variety of noninvasive pulmonary gas exchange measurements.

Adult↗
PubMed1977

Prolonged administration of bleomycin without clinical toxicity. Therapy with 2,700 units over four years.

A 26-year-old white man with stage 4-B Hodgkin's disease resistant to conventional chemotherapy obtained complete remission with administration of bleomycin. Maintenance of this remission required continued therapy with bleomycin. The patient received a total of 2,700 units of bleomycin over a 51-month period without signs or symptoms of pulmonary toxicity. Serial studies of pulmonary function have shown a stable forced vital capacity and minimally decreased total lung volume and pulmonary diffusing capacity. This case demonstrates the ability of a patient to tolerate massive cumulative doses ob bleomycin over a protracted period without severe loss of pulmonary function.

Adult↗
PubMed1988

Acute mercury poisoning and mercurial pneumonitis from gold ore purification.

We describe four men who had symptoms of acute mercury poisoning following exposure to mercury vapor. They were attempting home gold ore purification using a gold-mercury amalgam and sulfuric acid. Three of the four patients required treatment with penicillamine. The clinical and laboratory data are presented along with pulmonary function test results. Long-term follow-up of one patient indicates residual morbidity, with continued reduction in pulmonary diffusing capacity. This suggests permanent impairment of pulmonary function despite prompt chelation therapy.

Acute Disease↗
PubMedDate not supplied

Pulmonary hypertension in a child with mixed connective tissue disease.

Mixed connective tissue disease (MCTD) is characterized by high titers of antibody to ribonucleoprotein (RNP) in patients with features of several rheumatic diseases. We describe a child whose MCTD included arthritis, Raynaud's phenomenon, mucocutaneous ulcerations, sclerodermatous skin changes, restrictive lung disease, reduced carbon monoxide pulmonary diffusing capacity, abnormal esophogeal motility, and severe pulmonary hypertension. High antibody titers to ds-DNA and RNP were present. Clinical improvement followed therapy with prednisone and cyclophosphamide. Improvement in the degree of pulmonary hypertension was documented by repeat cardiac catheterization 8 months after the initiation of combination therapy.

Adolescent↗
PubMed1990

A morphological and morphometric study of the prosimian lung: the lesser bushbaby Galago senegalensis.

The lung of the lesser bushbaby (Galago senegalensis) has been investigated morphologically and morphometrically using the transmission and scanning electron microscopes. Grossly and microscopically, the bushbaby lung was found to be essentially similar to that of the other primates and the mammals in general. Subtle morphometric differences were, however, observed, with the bushbaby lung being generally structurally less sophisticated than that of the other primates on which comparable data are available, except for man. The weight-specific surface area of the blood-gas (tissue) barrier in G. senegalensis was 25 cm2 g-1. The thickness of the blood-gas barrier was 0.355 micron and the weight specific total anatomical pulmonary diffusing capacity 0.045 mlO2 sec-1 mbar1 kg-1. The morphological similarity of the galago lung to that of man gives sufficient grounds to justify its possible use in human pulmonary studies but caution has been called for in the general utilisation of primate tissues without first establishing their morphological characteristics, just because the primates are taken to be evolutionally close to man. The dearth of morphological studies on the various organ systems of the prosimians is pointed out.

Animals↗
PubMed1987

[Functional significance of lung siderosis in electrode welders].

56 electric arc welders found in a cross-sectional study to show pulmonary siderosis in full size x-rays were clinically examined. Looking for the discussed functional, relevance of such lung diseases in welders the diagnostic program included spirometry, flow-volume-curves, body-plethysmography, single breath diffusion capacity, pulmonary compliance and ergooxytensiometry. The results are supporting that "lung siderosis" in welders is associated with slight functional deterioration in the type of interstitial lung diseases.

Electrodes↗