Alveolar-capillary membrane diffusing capacity and its role in the functional capacity of chronic heart failure patients.
Explore the source record for details and available documents.
Chronic Disease↗
SEARCH · Search PubMed
Results for “Pulmonary Diffusing Capacity”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Diffuse idiopathic pulmonary neuroendocrine cell proliferation presenting as interstitial lung disease.
Pulmonary neuroendocrine cell (PNEC) hyperplasia typically occurs as an adaptive response in persons living at high altitudes and as a reactive response in the setting of lung injury. However, previous studies suggest that PNEC hyperplasia can occur in the absence of preexisting lung disease and may even give rise to airway disease through the development of pulmonary tumorlets and airway fibrosis and perhaps the release of paracrine secretions. We describe a patient with diffuse PNEC proliferation of a probable hyperplastic nature developing in the absence of a chronic pulmonary disorder who presented clinically with an interstitial lung process. Open lung biopsy displayed a florid intraepithelial population of PNEC diffusely involving the distal airways and alveoli with desquamation and filling of alveolar spaces by nests of PNEC. The presence of alveolar thickening was attributable to the intraepithelial proliferation of PNEC associated with interstitial fibrosis and accounted for mild reductions in the pulmonary diffusing capacity. The neuroendocrine differentiation of this proliferation was evident by light microscopic and ultrastructural examination. The absence of airway fibrosis and pulmonary tumorlets was in agreement with the lack of clinical airway disease in this case. The intraepithelial growth and absence of parenchymal invasion in this lesion favor a diffuse, florid PNEC hyperplasia with mild dysplastic features over a pulmonary neuroendocrine neoplasm.
Aged↗
Outcome measures for adult critical care: a systematic review.
OBJECTIVES: 1. To identify generic and disease specific measures of impairment, functional status and health-related quality of life that have been used in adult critical care (intensive and high-dependency care) survivors. 2. To review the validity, reliability and responsiveness of the measures in adult critical care survivors. 3. To consider the implications for future policy and to make recommendations for further methodological research. 4. To review what is currently known of the outcome of adult critical care. METHODS DATA SOURCES: Searches of electronic databases (MEDLINE, EMBASE, CINAHL, PsycLIT, The Cochrane Library and SIGLE) from 1970 to August 1998. Manual searches of five journals (1985-98) not indexed in electronic databases and relevant conference proceedings (1993-98). Reference lists of six existing reviews, plus snowballing from reference lists of all relevant articles identified. STUDY SELECTION: Randomised trials, non-randomised trials (cohort studies) and case series that included data on outcomes after discharge from adult (16 years and over) critical care. DATA EXTRACTION AND SYNTHESIS: If reported, the following data were extracted from each paper: patient characteristics (age, gender, severity of illness, diagnostic category) number of patients eligible for study, follow-up period, number of deaths before follow-up, number and proportion of survivors included in follow-up method of presentation of outcome data - proportion normal as defined by reference values, or aggregate value (e.g. mean or median), or aggregate values plus an indication of variance (e.g. standard deviation or inter-quartile range). Evidence for three measurement properties was sought for each outcome measure that had been used in at least two studies - their validity, reliability and responsiveness in adult critical care. If the authors did not report these aspects explicitly, an attempt was made to use the data provided to provide these measurement properties. For measures that were used in at least ten studies, information on actual reported outcomes were also extracted. RESULTS: MEASURES USED IN CRITICAL CARE: Measures of impairment were largely confined to the respiratory system so are almost certainly not appropriate for many critical care survivors. They can be categorised as respiratory volumes (e.g. vital capacity), gas flow within the respiratory system (e.g. forced expiratory volume in 1 second (FEV1)), pulmonary diffusing capacity (e.g. carbon monoxide diffusing capacity) and visualisation of the upper airway (e.g. bronchoscopy). Multiple tests are often performed. Eight measures of physical functional status were used, five generic and three disease-specific. The most frequently used generic measures were multi-item scales. Two single-item global measures attempted to capture a person's overall activity level or functional status. Five multi-item measures of mental functional status were used, four generic and one specific to trauma patients. The generic measures were either confined to assessing depressive symptoms or also encompassed a measure of anxiety. Measures of neuropsychological functioning relate to a person's cognition, attention, ability to process information and memory. Apart from one single-item measure, which focused on communication level, six multi-item measures were used with critical care survivors. Such measures are particularly appropriate for use with survivors of head injury or other neurological insult and, in that sense, they are disease-specific rather than generic measures. Single item measures of recovery were frequently used but researchers often invented their own, so there was little consistency in the wording. These measures had five principal foci - return to work, return to own home, degree of recovery, productivity and chronic health status. One multi-item scale was also used. (ABSTRACT TRUNCATED)
Adult↗
Pulmonary transit time and diffusing capacity in mammals.
Allometry is used as a tool to explain the apparent mismatch of oxygen consumption and diffusing capacity in the mammalian lung. By combining equations for pulmonary capillary volume and cardiac output, it is apparent that erythrocyte transit time through the lung must scale disproportionately to body mass. This inequality is a consequence of physical and mechanical properties setting optimal cardiac and respiratory frequencies. Because of much shorter transit times, the mean alveolar-capillary oxygen pressure difference increases as body size decreases. The time course of oxygen binding to hemoglobin may limit maximum oxygen consumption in the smallest mammals. To assure carbon dioxide diffusion equilibrium, levels of carbonic anhydrase are much higher in small than in large mammals. Because of the differences in transit time, the pulmonary diffusing capacity must scale linearly to body mass to assure adequate oxygen delivery in all mammals.
Animals↗
Lung function following treatment of malignant tumors with surgery, radiotherapy, or cyclophosphamide in childhood. A follow-up study after 11 to 27 years.
A group of 40 individuals were restudied at a median follow-up time of 18 years after chest surgery, chest irradiation, or cyclophosphamide treatment. Their median age at diagnosis was 4.5 years. Nineteen subjects were operated on in the chest area. Radiotherapy of the chest had been used in 21 and cyclophosphamide in 35 patients. Chest deformity was evident in 17 subjects. Chest radiographs showed some evidence of fibrosis in eight subjects and late effects of surgery in three subjects. In nine subjects some evidence of fixed obstruction was seen in spirometry. In three subjects pulmonary diffusion capacity was abnormal. Spirometry commonly showed a restrictive pattern of findings. The incidence of abnormalities in pulmonary function was highest among the patients diagnosed before age 3 years. Spirometry was more likely to reveal abnormalities in patients who had received irradiation to the chest. However, abnormalities in pulmonary function were fewer than anticipated.
Adolescent↗
The effects of age, sex, lung size, and hyperinflation on CT lung densitometry.
OBJECTIVE: To test our proposal that, on high-resolution CT scans, the relative area of the lung with attenuation values lower than -950 H (RA950) can be a measurement of pulmonary emphysema, we examine the possible influences of sex, age, lung size, and hyperinflation on CT lung densitometry. SUBJECTS AND METHODS: The RA950 and the mean lung density (MLD) were measured in 42 healthy subjects (21 men, 21 women) from 23 to 71 years old, in 10 patients with asthma before and after a bronchial challenge test, and in seven patients with asthma who have irreversible hyperinflation (defined as an increased total lung capacity). RESULTS: In the healthy subjects, we found no significant difference between sexes and no significant correlation between age and the MLD, but we found a significant correlation between age and the RA950. In addition, we found a significant correlation between the total lung capacity expressed as absolute values and both the RA950 and the MLD. We did not observe any effect of acute airflow limitation either on the MLD or on the RA950 in the asthmatic subjects after the bronchial challenge test. Likewise, we observed no change in either the MLD or the RA950 in the asthmatic subjects with chronic hyperinflation. CONCLUSION: This study shows that CT lung densitometry is influenced by total lung capacity and, to a lesser degree, by age. Thus, this study suggests that normal CT attenuation values for the lung should be established.
Absorptiometry, Photon↗
Effects of low concentrations of chlorine on pulmonary function in humans.
Eight healthy unacclimated volunteers were exposed to chlorine gas in concentrations of 0.5 or 1 ppm, and several pulmonary function measurements were made. Comparisons were made by paired t test between the percent change from base-line values obtained at various times after chlorine exposure and the percent change from base line at analogous times after a sham exposure. With the sham vs. 0.5-ppm exposure, there were trivial changes observed. Total lung capacity (TLC) was lower before 0.5-ppm exposure than before sham exposure, and the percent decrease in carbon dioxide pulmonary diffusing capacity was smaller 24 h after 0.5-ppm exposure than 24 h after sham exposure. With the sham vs. 1-ppm exposure, there were many differences in percent change from base line that were significant at the P less than 0.05 level or better. These were in forced vital capacity (FVC), forced expiratory volume at 1 s (FEV1), peak expiratory flow rate (PEFR), forced expiratory flow rate at 50 and 25% vital capacity (FEF50 and FEF25, respectively), and airway resistance (Raw). There were, in addition, significant changes after only 4 h of exposure. These were in FEV1, PEFR, FEF50, FEF25, TLC, Raw, and the difference in nitrogen concentration. Most of the test results had returned to normal by the next day. We conclude that even though chlorine at low concentrations does not produce any serious subjective symptoms, it adversely affects pulmonary function transiently.
Adult↗
Exercise-induced hypoxaemia in master athletes: effects of a polyunsaturated fatty acid diet.
Exercise-induced hypoxaemia (EIH) has been associated with an oxygen diffusion limitation. Because polyunsaturated fatty acids (PUFA) administration can modify cell membrane fluidity, we hypothesized that the importance of EIH could be reduced after a 6-week PUFA diet. Resting pulmonary functions and a maximal cycling test were performed before and after the diet, in eight master athletes -48 (SD 6 years)-. The partial pressure of O2 in arterial blood (PaO2), alveolar ventilation (VA) and ideal alveolar-arterial oxygen partial pressure difference (P(Ai-a) O2) were obtained at each exercise intensity. The extent of EIH at maximal exercise was significantly lower after PUFA [PaO2-17.2 (SEM 1.9) vs -12.9 (SEM 2.2)]. Before PUFA, VA accounted for 50% of the variance in the fall in P (Ai-a) for intensities below 80% maximal oxygen uptake (VO2max) and P(Ai-a)O2 for 60% between 70% and 100% VO2max. After PUFA, the reduction in EIH was highly correlated (r2 = 0.85; P < 0.001) to resulting changes in P(Ai-a)O2 and resting pulmonary diffusing capacity (DLCO)/VA but not with changes in ideal alveolar partial pressure of oxygen. The improvement in EIH following PUFA could be related to an increase in alveolar-arterial oxygen conductance following improved pulmonary diffusion.
Adult↗
Alveolitis during chrysotherapy for rheumatoid arthritis.
A patient who developed dry cough and increasing breathlessness during chrysotherapy for seropositive rheumatoid arthritis is presented. Chest radiograms were repeatedly normal, but there was a moderate decrease in pulmonary diffusing capacity. Transbronchial lung biopsy showed alveolitis. No cellular immunity to gold salts could be demonstrated in vitro. Pulmonary function improved after withdrawal of gold, indicating that chrysotherapy rather than systemic rheumatoid disease was the cause of the alveolitis.
Alveolitis, Extrinsic Allergic↗
Re-breathing vs single-breath TLCO in patients with unequal ventilation and diffusion.
The single-breath (SB) method for determining the transfer factor for carbon monoxide (TLCO) is of limited value for the detection of diffusion disorders on the alveolar level, because the results are influenced by unequal distribution of ventilation and diffusion. The rebreathing method (RB) is thought not to be influenced by these inequalities. To the authors' knowledge, no study has measured both TLCORB and TLCOSB systematically and compared them with regard to the influence of unequal ventilation and diffusion. Therefore, the present study measured total lung capacity (TLC) as well as TLCO, both with the RB vital capacity method and the SB method, using the same apparatus in 10 healthy subjects and in 35 patients with chronic obstructive pulmonary disease (COPD). These patients are known to have increased unequal ventilation and diffusion in comparison with healthy subjects. In the healthy subjects, a small difference was found between TLC measured with the RB method (TLCRB) divided by the predicted value (TLCRB/pred) and TLCSB/pred (mean difference 0.07; SE = 0.02); no significant difference was found between TLCORB divided by the predicted value of TLCOSB (TLCORB/pred) and TLCOSB/pred. In the COPD patients, however, TLCRB/pred was larger than TLCSB/pred (mean difference 0.17; SE = 0.02) and TLCORB/pred was larger than TLCOSB/pred (mean difference 0.23; SE = 0.05). Multiple regression analysis revealed that in the COPD patients, 54% of the variance of the difference between TLCRB/pred and TLCSB/pred, and 76% of the variance of the difference between TLCORB/pred and TLCOSB/pred, were explained by parameters related to unequal ventilation and diffusion. In 25 of the 35 COPD patients, TLCOSB/pred was less than 0.8, whereas in 11 of these 25 patients, TLCORB/pred was more than 0.8. This difference was significant (P = 0.0005). In these 11 patients, the SB measurement resulted in the incorrect diagnosis of a diffusion disorder on the alveolar level. The RB method, however, never resulted in the diagnosis of a diffusion disorder when TLCOSB/pred was larger than 0.8. It is concluded that in a significant number of COPD patients, TLCOSB is below the normal range, whereas TLCORB is not below the normal range. This difference between TLCORB and TLCOSB is related to the combined effect of unequal ventilation and diffusion, and is of clinical importance for the detection of a diffusion disorder on the alveolar level.
Adult↗
[Respiratory function tests in epidermoid cancers of the bronchi].
The results of functional tests are analyzed in 50 cases of epidermoid bronchial cancers. Severe disorders take place in almost every patient. In one patient out of two, there is an old distension already existing prior to the cancer; in other patients gas exchange disorders can be improved by the intervention. Moreover, from some results a spreading of cancer towards the mediastinum is to be feared.
Adult↗
Pulmonary functions in healthy females of Haryana.
Pulmonary functions including lung volumes and pulmonary diffusing capacity were assessed in 137 healthy female subjects, 18-52 years of age. The results were analysed by age-wise division of subjects in six groups. It was observed that there were wide variations in pulmonary function values from one individual to another depending upon age and height of the subjects. Majority of ventilatory functions attained maximum values by the age of 25 years while diffusion functions improved upto 35 years of age. Pulmonary functions showed better correlation with age and height as compared to weight. Taking into consideration age and height of subjects, regression equations for different pulmonary functions have been derived for female subjects.
Adolescent↗
Pulmonary O2-diffusing capacity in man by rebreathing: recent advances.
Explore the source record for details and available documents.
Animals↗
Malleability of the system in overcoming limitations: functional elements.
Three different views can be found in the literature concerning the classical question in exercise physiology: what limits maximal oxygen uptake in man? Some authors believe that the limitation is the maximal rate of oxygen delivery by the cardiovascular system. Others argue that oxygen uptake is limited by the capillary bed or metabolic capacity of skeletal muscle, and the third line of thought is that no single factor can be found to be directly limiting as all links in the oxygen transport are so closely matched. The stand taken in this paper is that the skeletal muscle of man can be excluded as a limiting factor for maximal oxygen uptake in whole body exercise. It can be shown, by direct measurements, that in sedentary and in trained man maximal perfusion and oxygen utilization of skeletal muscle is so high that if all muscles in the body were engaged in intense exercise, the cardiac pump function would have to be 2-3 fold larger than it is. What happens in whole body exercise is that each muscle group receives only a fraction of the blood it can accommodate. The primary role for a larger capillary network observed in trained muscles is to keep or extend mean transit time. Elevated mitochondrial enzyme activities affect the metabolic response (i.e. lipid oxidation is elevated in trained muscles). However, these adaptations are not necessary for increasing the maximal oxygen uptake of man, as the capacity of the heart is limiting. Improved training techniques (which induce even larger improvements in cardiac pump function) may reveal that pulmonary diffusion capacity is the limiting factor.
Adaptation, Physiological↗
Pulmonary gas exchange and ventilation during hemodialysis.
Hemodialysis-induced hypoxemia has been explained by several mechanisms: pulmonary microembolization, decreased pulmonary diffusing capacity, fall in alveolar oxygen tension, hypoventilation and ventilation/perfusion abnormalities. The objective of this study was to analyze the factors influencing pulmonary ventilation and gas exchange of 20 patients with chronic renal failure during hemodialysis performed under the following conditions: Group 1 (9 patients) dialyzed against an acetate dialysate with a cuprophan membrane; Group 2 (7 patients) dialyzed against acetate bubbled with CO2 with a cuprophan membrane; Group 3 (4 patients) similar to Group 1, but using a polyacrylonitrile membrane. Arterial and venous blood samples were obtained from the respective lines during the predialysis period (zero), at 30, 60, 120 180 and 240 min of hemodialysis, and 60 min post dialysis (300 min) for the measurement of pH, PCO2, PO2, HCO-3 and total CO2. The minute expired volume (VE), expired fractions of O2 (FEO2) and CO2 (FECO2), O2 consumption (VO2), CO2 elimination through the lungs (VCO2) and dialyzer, respiratory exchange ratio (R), dead space to tidal volume ratio (VD/VT), alveolar ventilation (VA) and alveolar-arterial O2 difference (delta AaPO2) were measured and a leukocyte count was performed for each period of hemodialysis. The patients in Groups 1 and 3 showed a significant drop in ventilation and PaO2, a slight decrease in PAO2 and a significant increase in delta AaPO2. The patients in Groups 1 and 2 showed a significant leukopenia at 30 min of hemodialysis. The volume of CO2 eliminated across the dialyzer was very similar for the three groups of patients. Group 2 did not show any drop in ventilation or PaO2. For Group 2 venous line pH was very low and PCO2 was within the normal range, in contrast to the normal or high pH and low PCO2 shown by Groups 1 and 3. This study indicates that the drop in PaO2 was partially the consequence of a slight decrease in PAO2, but mainly due to the increase in delta AaPO2. Thus the most likely cause of the decrease in PaO2 was the VA/Q imbalance brought about by a drop in ventilation. The drop in ventilation was linked not only to the volume of CO2 eliminated across the dialyzer, but also to the amount of CO2 delivered to the lungs, and to the pH and PCO2 of the venous line.
Adult↗
Applicability of the single-breath carbon monoxide diffusing capacity in a Norwegian Community Study.
The test of single-breath diffusing capacity for carbon monoxide (DLCO) has been widely used in population surveys. However, little is known about the effect of meeting or failing to meet the criteria for acceptability of this test. The American Thoracic Society (ATS) recommends a breathholding time of 9 to 11 s, two measurements within +/- 10% or 3 ml CO(STPD)/min/mm Hg of the average DLCO, and an inspiratory vital capacity (IVC) of at least 90% of the largest previously measured forced vital capacity (FVC) as criteria for this test. The objective of the present study was to examine the extent to which these criteria were met in a community study. To do this, a random sample of 3,740 persons, aged 15 to 70 yr, of the general population of the city of Bergen and 11 surrounding municipalities on the southwest coast of Norway were enrolled in a two-phase cross-sectional study. In the second phase, a stratified sample (n = 1,512) of the respondents to the postal questionnaire used for recruitment for the study (n = 3,370) were invited to a clinical and respiratory physiologic examination that included the DLCO test. The attendance rate was 84% (1,275 of 1,512). In the examination, all subjects were able to maintain a breathholding time of 9 to 11 s, and 98% had two DLCO values within +/- 10% or 3 ml CO(STPD)/min/mm Hg of the average DLCO. The criterion of an IVC of at least 90% of FVC in the two tests was met by 68% of the subjects. Younger age was an independent predictor of failure to meet the required criteria. Thus, only two-thirds of the participants fulfilled all of the ATS criteria for the DLCO test, the main reason for failure being an IVC of less than 90% FVC. This should not necessarily lead to the exclusion from further analysis of those failing to meet this criterion.
Adolescent↗
The alveolar-capillary membrane diffusing capacity and the pulmonary capillary blood volume in heart transplant candidates.
OBJECTIVES: To determine the mechanism of impairment of pulmonary transfer factor for carbon monoxide (TL(CO)) in heart transplant candidates, as this is the most common lung function abnormality. SETTING: Regional cardiopulmonary transplant centre. METHODS: TL(CO) and its components (the diffusing capacity of the alveolar-capillary membrane (D(M)) and the pulmonary capillary blood volume (V(C))) were measured using the Roughton and Forster method and the single breath technique in 38 patients with severe chronic heart failure awaiting heart transplantation (mean age 51 years, range 19 to 61; mean left ventricular ejection fraction 12.8%). Results were compared with data from 26 normal subjects (mean age 47 years, range 27 to 62). RESULTS: Mean per cent predicted TL(CO), D(M), and V(C) were significantly reduced in patients (69.9%, 81.4%, and 80.2% of predicted, respectively) compared with controls (97.7%, 100.1%, and 102.3% of predicted, respectively, p < 0.001). The relative contribution of the two components of TL(CO) in patients was similar to that of normal subjects, with each component accounting for approximately 50% of the total resistance to diffusion (1/TL(CO)). CONCLUSIONS: TL(CO) impairment in patients with severe chronic heart failure awaiting heart transplantation results from a proportionate reduction in both D(M) and V(C), suggesting a significant disturbance of the pulmonary vascular bed.
Adult↗
Amniotic fluid embolism: definitive diagnosis in a survivor.
Explore the source record for details and available documents.
Adult↗