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PubMed2005

Effect of body position on gas exchange in patients with idiopathic pulmonary alveolar proteinosis: no benefit of prone positioning.

BACKGROUND: Prone positioning may improve oxygenation in patients with acute lung injury/ARDS. However, the beneficial effect of prone positioning on gas exchange has never been investigated in patients with diffuse pulmonary infiltrates who breathe spontaneously. OBJECTIVE: To evaluate the effect of body position on gas exchange in patients with idiopathic pulmonary alveolar proteinosis (PAP) with special reference to the benefit of prone positioning. DESIGN: A prospective study. SETTING: Tertiary medical center. PATIENTS AND METHODS: Eight patients with PAP were studied on 25 occasions using spirometry, body plethysmography, and single-breath diffusing capacity of the lung for carbon monoxide (Dlco). Arterial blood gas levels were measured in the sitting position and in four lying positions randomly while patients breathed room air. To serve as control subjects, 16 age-matched healthy hospital personnel were studied. To evaluate the impact of oxygen therapy on positional effect in gas exchange, arterial blood gas levels were measured in the supine and prone positions in some PAP patients while breathing 40% oxygen. RESULTS: Normal to varying degrees of restrictive ventilatory defect and gas exchange impairment, as evidenced by Dlco, Pao(2), and alveolar-arterial oxygen pressure difference (P[A-a]O(2)), were found in PAP patients. The ventilatory function parameters correlated positively with Pao(2) and negatively with P(A-a)O(2). The values of Pao(2) and P(A-a)O(2) measured in four lying positions showed no significant difference in both PAP patients and healthy control subjects. Furthermore, the differences in Pao(2) and P(A-a)O(2) between measurements made in the supine and prone positions and the ratio of Pao(2) measured in the prone position/Pao(2) measured in the supine position were comparable between PAP patients and healthy control subjects. Arterial blood gas levels showed no significant difference between measurements made in PAP patients in the supine and prone positions while breathing 40% oxygen. CONCLUSIONS: Positional change did not significantly affect gas exchange, and no benefit of prone positioning was found in both PAP patients and healthy control subjects. Further studies are needed to verify the benefit of prone ventilation in patients with diffuse pulmonary disorders who breathe spontaneously.

Adult↗
PubMed2004

Thin-section CT abnormalities and pulmonary gas exchange impairment in workers exposed to asbestos.

PURPOSE: To evaluate the relationship between abnormalities at thin-section computed tomography (CT) and indexes of pulmonary gas exchange impairment at rest and during moderate exercise in workers exposed to asbestos. MATERIALS AND METHODS: Eighty-two workers with long-term exposure to asbestos and abnormal thin-section CT findings underwent respiratory physiologic measurements at rest (lung diffusing capacity, Dlco) and during exercise (oxygen uptake-corrected alveolar-arterial pressure difference for oxygen, DeltaP[A-a]O(2)/VO(2)). CT results were compared with physiologic measurements of impairment in gas exchange (Dlco < 70% predicted value and/or DeltaP[A-a]O(2)/VO(2) > 20 mm Hg. L. min(-1)). The CT findings were divided into five categories by using a previously described method. Odds ratios and 95% CIs for gas exchange defects were calculated for patients grouped according to CT findings. Logistic regression analysis was performed with gas exchange as the dependent response and CT abnormalities as independent variables. RESULTS: A significant association was found between extent of disease at CT and impairment of gas exchange (P <.01). Probability of functional impairment was increased with multifocal (class II) and diffuse (class III) CT abnormalities, particularly when several lesion types were found concomitantly. Logistic regression analysis demonstrated significant association of parenchymal bands (odds ratio, 6.20; 95% CI: 1.99, 19.22) and subpleural nodules (odds ratio, 3.83; 95% CI: 1.23, 11.89) with functional impairment. Presence and number of pleural plaques did not improve model accuracy for gas exchange impairment prediction (P >.05). CONCLUSION: Thin-section CT grading of interstitial lung disease is useful in assessing the likelihood of pulmonary gas exchange impairment at rest (Dlco) and during exercise (DeltaP[A-a]O(2)/VO(2)) in workers with long-term asbestos exposure.

Adult↗
PubMed1994

Mixed expired nitric oxide in primary pulmonary hypertension in relation to lung diffusion capacity.

The mixed expired nitric oxide (NO) production of the lungs of patients with primary pulmonary hypertension (PPH) and normal subjects was measured to determine the relationship between NO production and the diffusion capacity of the lung (KCO). Expired air was collected from eight patients with PPH and 20 healthy volunteers for analysis by a chemiluminescent analyser. Mean pulmonary artery pressure in the PPH patients was 59.5 +/- 6.45 mmHg and their mean cardiac output was 2.95 +/- 0.35 l/min. All patients and subjects underwent measurements of FEV1, VC and KCO. The rate of production of NO in mixed exhaled air was lower in the PPH group compared to the controls (2.85 +/- 0.7 vs. 4.69 +/- 0.35 nM/min; p < 0.05). There was a good correlation of expired NO with the KCO (r = 0.7; n = 30; p < 0.001). When corrected, KCO differences in exhaled NO were not significant (p = 0.09). We conclude that the low exhaled NO observed in PPH patients is a reflection of the reduced blood capillary volume in these patients rather than a decreased basal production of NO.

Adult↗
PubMed2002

Lung function during and after prolonged head-down bed rest.

We determined the effects of prolonged head-down tilt bed rest (HDT) on lung mechanics and gas exchange. Six subjects were studied in supine and upright postures before (control), during [day 113 (D113)], and after (R + number of days of recovery) 120 days of HDT. Peak expiratory flow (PF) never differed between positions at any time and never differed from controls. Maximal midexpiratory flow (FEF(25-75%)) was lower in the supine than in the upright posture before HDT and was reduced in the supine posture by about 20% between baseline and D113, R + 0, and R + 3. The diffusing capacity for carbon monoxide corrected to a standardized alveolar volume (volume-corrected DL(CO)) was lower in the upright than in the supine posture and decreased in both postures by 20% between baseline and R + 0 and by 15% between baseline and R + 15. Pulmonary blood flow (Q(C)) increased from R + 0 to R + 3 by 20 (supine) and 35% (upright). As PF is mostly effort dependent, our data speak against major respiratory muscle deconditioning after 120 days of HDT. The decrease in FEF(25-75%) suggests a reduction in elastic recoil. Time courses of volume-corrected DL(CO) and Q(C) could be explained by a decrease in central blood volume during and immediately after HDT.

Adult↗
PubMed2000

[Influence of berotec inhalations on pulmonary gas exchange in patients with bronchial asthma].

AIM: To determine mechanisms inducing changes in lung gas exchange after berotec inhalation in patients with bronchial asthma (BA). MATERIALS AND METHODS: A study was made of external respiration function including estimation of lung transfer factor (TLCO sbh.) and its components--transfer coefficient (KCO), membrane diffusion capacity (DM), pulmonary capillary blood volume (Vc)--by the single breath holding method on CO in 14 healthy persons and 39 patients with BA before and after berotec inhalation. The data were obtained in the absolute values and their changes after berotec inhalation were measured in percent to initial ones. RESULTS: In healthy subjects we did not observe changes of TLCO sbh. and its components after berotec inhalation, only an insignificant decrease of VA eff. was registered (p < 0.01). After berotec inhalation a considerable improvement in Sgaw, FEV1, RPV and a decrease of TLCO sbh., KCO were observed. Changes in TLCO sbh. were caused by a decrease in DM without changes in VA eff. in BA patients with initial normal values of KCO. In patients with smaller initial values of KCO moderate improvement of bronchial permeability without changes in KCO, PaO2 were observed. These changes occurred due to a decrease of VA eff. CONCLUSION: Changes of the transfer factor and its components in patients with BA reflect two types of adaptation reactions in response to berotec inhalation and their role in mechanisms of compensation of gas exchange in the lungs.

Administration, Inhalation↗
PubMed1978

[Effects of isovolaemic haemodilution on pulmonary gas exchange and haemodynamics (author's transl)].

In experiments on 11 closed chest dogs the behaviour of pulmonary gas exchange and haemodynamics during isovolaemic haemodilution with 6% dextran was studied. The dogs were ventilated artificially (IPPB, PEEP = 0) with room air. After haemodilution a slight increase of arterial PO2 from 86 to 92 mm Hg was found. In another series of experiments an inspiratory O2-concentration of 25% was applied resulting in an increase of arterial PO2 from 106 to 113 mm Hg. In both series a decrease of alveolararterial PO2 gradients was observed. Effective pulmonary capillary blood flow varied in accordance with changes of cardiac output. Thus intrapulmonary shunt is supposed to have remained constant. The changes of pulmonary O2 diffusing capacity could be explained by the effect of haemodilution per se. At the end of the experiments ventilation was changed by adding a positive endexpiratory pressure of 8 cm H2O resulting in a decrease of arterial PO2 and a steep fall of cardiac output. In conclusion, isovolaemic haemodilution leads to only negligible variations of pulmonary gas exchange which should not be of any clinical importance.

Animals↗
PubMed1990

Results of single-lung transplantation for bilateral pulmonary fibrosis. The Toronto Lung Transplant Group.

Between November 1983 and August 1989, we performed single-lung transplantation for end-stage pulmonary fibrosis in 20 patients. Nine patients (45 percent) who survived for more than one year form the basis of this report. Before surgery, the nine survivors had severe restrictive lung disease, with a mean (+/- SD) vital capacity (VC) of 43 +/- 9 percent, a forced expiratory volume in one second (FEV1) of 50 +/- 9 percent, and a single-breath diffusing capacity (DLCO) of 36 +/- 9 percent of predicted values. One year after transplantation, the patients' VC had reached 69 +/- 10 percent, FEV1 79 +/- 15 percent, and DLCO 62 +/- 16 percent of predicted values. Relative perfusion to the transplanted lung rose from 63 +/- 14 percent (three days after surgery) to 77 +/- 7 percent within three months and stayed constant or increased slightly thereafter. Before surgery, despite supplemental oxygen at flow rates varying from 1 to 9 liters per minute, none of the patients could exercise beyond stage 1/2 (2.7 km [1.7 miles] per hour, 5 percent grade) on a modified Bruce treadmill-exercise protocol. All eight patients tested one year or more after transplantation achieved at least stage 1 (2.7 km [1.7 miles] per hour, 10 percent grade), and usually a higher stage, without supplemental oxygen. Arterial oxygen tension returned to normal values in most patients (87 +/- 13 mm Hg), and supplemental oxygen, which all patients required before surgery, was no longer needed by any patient after transplantation. We conclude that in carefully selected patients with end-stage pulmonary fibrosis, single-lung transplantation is an effective treatment.

Adolescent↗
PubMed1992

Conducting airway gas exchange: diffusion-related differences in inert gas elimination.

We studied CO2 and inert gas elimination in the isolated in situ trachea as a model of conducting airway gas exchange. Six inert gases with various solubilities and molecular weights (MW) were infused into the left atria of six pentobarbital-anesthetized dogs (group 1). The unidirectionally ventilated trachea behaved as a high ventilation-perfusion unit (ratio = 60) with no appreciable dead space. Excretion of higher-MW gases appeared to be depressed, suggesting a MW dependence to inert gas exchange. This was further explored in another six dogs (group 2) with three gases of nearly equal solubility but widely divergent MWs (acetylene, 26; Freon-22, 86.5; isoflurane, 184.5). Isoflurane and Freon-22 excretions were depressed 47 and 30%, respectively, relative to acetylene. In a theoretical model of airway gas exchange, neither a tissue nor a gas phase diffusion resistance predicted our results better than the standard equation for steady-state alveolar inert gas elimination. However, addition of a simple ln (MW) term reduced the remaining residual sum of squares by 40% in group 1 and by 83% in group 2. Despite this significant MW influence on tracheal gas exchange, we calculate that the quantitative gas exchange capacity of the conducting airways in total can account for less than or equal to 16% of any MW-dependent differences observed in pulmonary inert gas elimination.

Animals↗
PubMedDate not supplied

Standardized quantitative high resolution CT in lung diseases.

Twenty-seven patients with diffuse fibrosing alveolitis (DFA), 27 patients with granulomatous lung disease (GLD), 3 patients with homozygous alpha 1-proteinase inhibitor deficiency (alpha 1-PID), and 6 healthy volunteers (C) were studied using thin section high resolution CT (HRCT) at 50% of actual vital capacity (VC), determined and controlled spirometrically during each exposure. A fast contour tracing algorithm was used to isolate the lung parenchyma followed by a quantitative histogram analysis of the frequencies of CT values. Mean CT values enabled us to discriminate significantly between the groups of C and alpha 1-PID. Significant differences were found between the groups of GLD and DFA versus C by applying suitably selected intervals of CT values. Moreover, if the patients were assigned to four different groups according to their lung function results (normal, restrictive, obstructive, restrictive and obstructive), again significant differences existed with respect to defined intervals of CT values. Mean CT values showed a significant negative correlation with lung function tests representative of lung parenchymal disease, i.e., VC, diffusing capacity, and exercise PaO2. Moreover, CT values ranging from -899 to -800 HU correlated positively, whereas CT value frequencies above -699 HU correlated inversely with these same lung function parameters. These results indicated that certain intervals of CT values do reflect functionally different abnormalities of lung parenchyma. It is concluded that an analysis of frequencies of CT values determined by spirometrically standardized HRCT provides objective quantitative data that reflect changes of pulmonary structure corresponding to lung function impairments. Thus, spirometrically standardized HRCT may be helpful for evaluating and staging patients with diffuse pulmonary disease.

Adult↗
PubMed1994

Clinical and functional assessment of patients with idiopathic pulmonary fibrosis: results of a 3 year follow-up.

The purpose of this study was to analyse the information provided by different techniques used in the assessment of patients with idiopathic pulmonary fibrosis (IPF) and their role in the prediction of lung function decline with the decline. Twenty seven subjects with IPF (55 +/- 14 (mean +/- SD) yrs) were studied at the initial staging. Nineteen of them (70%) were included in a follow-up over 3 yrs (32 +/- 6 months), whilst the remaining 8 patients were lost to follow-up. During the period of the study, 6 of the 19 patients died. A significant correlation between diffusing capacity of the lungs for carbon monoxide (DLCO) (and carbon monoxide transfer coefficient (KCO) = DLCO/alveolar volume (VA)) and the increase in alveolar-arterial oxygen tension difference (A-aPO2) during exercise (delta A-aPO2) was observed at diagnosis (r = -0.58). Despite the treatment with prednisone (1 mg.kg-1 daily during 4 weeks, tapered to an individualized maintenance daily dose of 15-30 mg), the 13 patients controlled throughout the whole period of the study showed a marked impairment in lung volumes; forced vital capacity (FVC) -0.46 +/- 0.09 l, from 69 +/- 16 to 52 +/- 11% of predicted, and total lung capacity (TLC) -0.39 +/- 0.11 l, from 75 +/- 16 to 62 +/- 14%, and in DLCO -0.6 +/- 0.2 mmol.min-1.kPa-1, from 56 +/- 15 to 47 +/- 18%, predicted. By contrast, both mean arterial oxygen tension (PaO2) and A-aPO2 at rest remained unchanged throughout the 3 yrs follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1975

Pulmonary calcification in chronic dialysis patients. Clinical and pathologic studies.

A prospective study of 31 chronically hemodialyzed patients was made to investigate the incidence and pathology of pulmonary calcification and the relation of the latter to ventilatory function. Fifteen of the patients have died thus far; 9 had evidence of lung calcification. The lesions occurred predominately in alveolar septa and were associated with varying degrees of fibrosis and alveolar septal thickening. Only one patient had X-ray evidence of calcification. An X-ray diffraction analysis showed a predominant pattern of whitlockite (CaMg)3(Po4)2 in deposits. Patients with the severest pulmonary calcification had abnormalities of vital capacity, carbon monoxide diffusion, and Po2. Serum calcium levels were slightly higher in patients with calcification, but there was no measurable association with the duration of dialysis, serum phosphorus, calcium X phosphorus product, magnesium, bicarbonate, or arterial pH. These data show that pulmonary calcification occurs with high frequency in patients undergoing long-term hemodialysis and that such lesions are associated with restrictive and diffusion ventilatory defects.

Adult↗
PubMed1987

Radiation pneumonitis and fibrosis following split-course radiation therapy for lung cancer. A radiologic and physiologic study.

Radiographic signs of radiation pneumonitis and fibrosis were assessed and pulmonary function monitored in lung cancer patients after two different split-course radiation therapy schedules, one with a rest interval of 3 weeks and the other with a rest interval of 5 weeks, the total radiation dose being the same in both treatments (55 Gy/20 fractions/7 or 9 weeks). Post-mortem findings were analysed when available. Spirometric measurement of vital capacity, determination of diffusing capacity for carbon monoxide (DL) and alveolar volume with the single breath technique, and determination of regional distribution of lung perfusion by two different techniques, radiospirometry and gamma camera digital display following intravenous injection of 133Xe, were carried out before and at various times after the completion of irradiation. Of the physiologic parameters, only DL showed a significant decrease 6 as well as 9 months post-treatment (p less than 0.05). No difference between the two treatment schedules could be shown with regard to grade or time pattern of radiologic changes or decrease in DL. The findings suggest that measurement of DL may be of value in monitoring patients included in research protocols for radiation therapy of lung cancer as well as in selection of patients for this treatment.

Aged↗
PubMed2002

Pulmonary gas exchange abnormalities in liver transplant candidates.

Abnormal diffusing capacity is the commonest pulmonary dysfunction in liver transplant candidates, but severe hypoxemia secondary to hepatopulmonary syndrome and significant pulmonary hypertension are pulmonary vascular manifestations of cirrhosis that may affect the perioperative course. We prospectively assessed the extent of pulmonary dysfunction in patients referred for liver transplantation. A total of 57 consecutive patients with chronic liver disease were evaluated. All patients had a chest radiograph, standing arterial blood gas on room air, pulmonary function testing, and Doppler echocardiogram. Those patients with arterial hypoxaemia (PaO(2) < 10 kPa) also underwent (99m)Tc-macroaggregated albumin lung scan, and nine patients had agitated normal saline injection during echocardiography to define further the existence of pulmonary vascular dilatation. Reduced diffusing capacity for carbon monoxide less than 75% of the predicted value was found in 29 of 57 (51%) patients. Although elevated alveolar-arterial oxygen tension difference was detected in 35% (20/57) of the patients, only four (7%) patients had hypoxemia. We were unable to find evidence of intrapulmonary vascular dilatation either on the lung scan or saline-enhanced echocardiography in any of these patients. Reduction in diffusing capacity for carbon monoxide was noted in 75% (18/24) of patients who were transplanted for primary biliary cirrhosis and was accompanied by widened alveolar-arterial oxygen tension in 10 out of 18 (56%) of patients. This study shows that in liver transplant candidates, diffusion impairment and widened alveolar-arterial oxygen tension difference were frequently detected, especially in patients with primary biliary cirrhosis.

Adolescent↗
PubMed2004

Respiratory outcome in school-aged, very-low-birth-weight children in the surfactant era.

AIM: To assess respiratory outcome and its predictors during the surfactant era in very-low-birth-weight (VLBW, birth weight <1500g) schoolchildren with and without bronchopulmonary dysplasia (BPD). METHODS: At 7-8 years of age, 34 VLBW children with BPD diagnosed at a postnatal age of 28 d underwent flow-volume spirometry, metacholine challenge, bronchodilatation test, whole body plethysmography and diffusion capacity measurement. Fourteen of them had not recovered from BPD by a corrected gestational age of 36 wk (sBPD subgroup). The age- and sex-matched control groups comprised 34 VLBW cases without BPD and 34 term children. RESULTS: Current respiratory symptoms in contact with cold air and/or upon exercise were reported in one-third of the VLBW children. Only half of the symptomatic VLBW cases without BPD had inhaled medications. Compared with term controls, the BPD cases had lower forced expiratory volume in 1 s (FEV1), higher ratio of residual volume to total lung capacity and higher airway resistance. Lower FEV1 and specific conductance were found in the sBPD subgroup compared to both control groups. Additionally, their vital capacity was lower than in term controls. A higher rate of bronchial hyper-reactivity and lower diffusion capacity of the lungs were detected in VLBW as against term cases. Low birth weight, long duration of oxygen therapy, low socio-economic status and exposure to animal dander emerged as predictors of poorer respiratory outcome. CONCLUSION: In the surfactant era, birth weight, neonatal respiratory morbidity, as well as later environmental factors appear to affect the respiratory outcome of VLBW children. However, careful pulmonary follow-up of all VLBW children seems to be indicated regardless of the severity of neonatal respiratory problems.

Bronchopulmonary Dysplasia↗
PubMed2003

Alveolar gas exchange in patients with type 2 diabetes mellitus.

The present study has been conducted to quantify and compare the capacity of gas exchange in patients with type 2 diabetes mellitus (DM) and healthy controls and also to investigate the effects of various factors on alveolar capillary permeability. A total of 37 subjects, 25 patients with DM and 12 healthy controls were recruited for the study. All the participants were evaluated with simple spirometric tests and simple breath carbonmonoxide (CO) diffusion test (DLCO). The ratio of DLCO value to the alveolar ventilation (VA) was used to assess alveolar membrane permeability. Diabetic patients were also evaluated in detail with respect to degenerative diabetic complications including the presence of microalbuminuria, advanced nephropathy, sensorial and autonomic neuropathy, retinopathy, hypertension and macrovascular disease. The results of simple spirometric tests which determined lung capacity were similar in the diabetic patients and the healthy controls. Ratio of DLCO/VA, which determines alveolar membrane permeability, revealed statistically significant decline in pulmonary gas exchange in the diabetic group (p: 0.037). Pearson correlation analysis revealed statistically significant correlation between duration of diabetes mellitus, age and urinary albumin excretion with DLCO/VA values (Pearson: -0.726, p: 0.001; Pearson: -0.438, p: 0.036; Pearson: -0.472, p: 0.023 respectively). This study demonstrated the decreased alveolar gas exchange capacity in diabetic patients compared with healthy controls. Detrimental effects of DM on alveolar capillaries were found to be correlated with age, duration of DM and urinary albumin excretion. Microalbuminuria was the only significant predictor of DLCO/VA.

Adult↗