Showing papers on "Pulmonary diffusion published in 2016"

Impaired Pulmonary Diffusion in Heart Failure With Preserved Ejection Fraction

Abstract: Objectives The purpose of this study was to compare measures of gas exchange at rest and during exercise in patients with heart failure and preserved ejection fraction (HFpEF) with age- and sex-matched control subjects. Background Patients with HFpEF display elevation in left heart pressures, but it is unclear how this affects pulmonary gas transfer or its determinants at rest and during exercise. Methods Patients with HFpEF (n = 20) and control subjects (n = 26) completed a recumbent cycle ergometry exercise test with simultaneous measurement of ventilation and gas exchange. Diffusion of the lungs for carbon monoxide (DLCO) and its subcomponents, pulmonary capillary blood volume (VC) and alveolar-capillary membrane conductance (DM), were measured at rest, and matched for low-intensity (20 W) and peak exercise. Stroke volume was measured by transthoracic echocardiography to calculate cardiac output. Results Compared with control subjects, patients with HFpEF displayed impaired diastolic function and reduced exercise capacity. Patients with HFpEF demonstrated a 24% lower DLCO at rest (11.0 ± 2.3 ml/mm Hg/min vs. 14.4 ± 3.3 ml/mm Hg/min; p Conclusions Subjects with HFpEF display altered pulmonary function and gas exchange at rest and especially during exercise, which contributes to exercise intolerance. Novel therapies that improve gas diffusion may be effective to improve exercise tolerance in patients with HFpEF.

Surgical embolectomy compared to thrombolysis in acute pulmonary embolism: morbidity and mortality

Abstract: Objectives The aim of this study was to investigate the long-term outcome after acute high- and intermediate-risk pulmonary embolism (PE) treated with surgical embolectomy or thrombolysis. Methods Prospective follow-up including assessment of 30-day and 5-year mortality. Clinical evaluation including ventilation/perfusion scintigraphy by single-photon emission computed tomography in combination with X-ray computed tomography, measurement of pulmonary diffusion impairment, spirometry and echocardiography. Results A total of 136 patients (64 with high-risk and 72 with intermediate-risk PE) were included, 80 participated in the clinical follow-up, 16 were alive but declined follow-up and 40 were deceased. For high-risk PE patients the median time to clinical follow-up was 31 months [8–133]. No significant difference was observed in 30-day (Plog-rank = 0.16) or 5-year (Plog-rank = 0.53) mortality between patients treated with surgical embolectomy or thrombolysis. Ventilation/perfusion mismatch identified residual emboli in 4 patients (31%) treated with surgical embolectomy compared to 16 (76%) treated with thrombolysis (P = 0.009). Pulmonary diffusion impairment was identified in 4 patients (31%) treated with surgical embolectomy in comparison to 15 (71%) treated with thrombolysis (P = 0.02). In intermediate-risk PE patients, no significant difference in mortality (Plog-rank = 0.51 and 0.86), diffusion impairment or ventilation/perfusion mismatch was found between patients treated with surgical embolectomy or thrombolysis. Conclusions Surgical embolectomy for acute high-risk PE has similar mortality, but better outcome on pulmonary end-points when compared to thrombolysis. Patients with high-risk PE could benefit from being referred to a centre with both specialized cardiology and cardiothoracic surgery for interdisciplinary evaluation of optimal treatment strategy.

Chronic Hypoxia Accentuates Dysanaptic Lung Growth.

Abstract: Rationale: Adults born and raised at high altitudes have larger lung volumes and greater pulmonary diffusion capacity compared with adults at low altitude; however, it remains unclear whether the air and tissue volumes have comparable increases and whether there is a difference in airway size.Objectives: To assess the effect of chronic hypoxia on lung growth using in vivo high-resolution computed tomography measurements.Methods: Healthy adults born and raised at moderate altitude (2,000 m above sea level; n = 19) and at low altitude (400 m above sea level; n = 23) underwent high-resolution computed tomography. Differences in total lung, air, and tissue volume, mean lung density, as well as airway lumen and wall areas in anatomically matched airways were compared between groups.Measurements and Main Results: No significant differences for age, sex, weight, or height were found between the two groups (P > 0.05). In a multivariate regression model, altitude was a significant contributor for total lung volume...

Why are high-altitude natives so strong at altitude? Maximal oxygen transport to the muscle cell in altitude natives

Abstract: In hypoxia aerobic exercise performance of high-altitude natives is suggested to be superior to that of lowlanders; i.e., for a given altitude natives are reported to have higher maximal oxygen uptake (VO2max). The likely basis for this is a higher pulmonary diffusion capacity, which in turn ensures higher arterial O2 saturation (SaO2) and therefore also potentially a higher delivery of O2 to the exercising muscles. This review focuses on O2 transport in high-altitude Aymara. We have quantified femoral artery O2 delivery, arterial O2 extraction and calculated leg VO2 in Aymara, and compared their values with that of acclimatizing Danish lowlanders. All subjects were studied at 4100 m. At maximal exercise SaO2 dropped tremendously in the lowlanders, but did not change in the Aymara. Therefore arterial O2 content was also higher in the Aymara. At maximal exercise however, fractional O2 extraction was lower in the Aymara, and the a-vO2 difference was similar in both populations. The lower extraction levels in the Aymara were associated with lower muscle O2 conductance (a measure of muscle diffusion capacity). At any given submaximal exercise intensity, leg VO2 was always of similar magnitude in both groups, but at maximal exercise the lowlanders had higher leg blood flow, and hence also higher maximum leg VO2. With the induction of acute normoxia fractional arterial O2 extraction fell in the highlanders, but remained unchanged in the lowlanders. Hence high-altitude natives seem to be more diffusion limited at the muscle level as compared to lowlanders. In conclusion Aymara preserve very high SaO2 during hypoxic exercise (likely due to a higher lung diffusion capacity), but the effect on VO2max is reduced by a lower ability to extract O2 at the muscle level.

Change in pulmonary diffusion capacity in a general population sample over 9 years.

Abstract: Rationale : Data on the change in diffusion capacity of the lung for carbon monoxide (DL CO ) over time are limited. We aimed to examine change in DL CO (ΔDL CO ) over a 9-year period and its predictors. Methods : A Norwegian community sample comprising 1,152 subjects aged 18–73 years was examined in 1987 and 1988. Of the 1,109 subjects still alive, 830 (75%) were re-examined in 1996/97. DL CO was measured with the single breath-holding technique. Covariables recorded at baseline included sex, age, height, weight, smoking status, pack years, occupational exposure, educational level, and spirometry. Generalized estimating equations analyses were performed to examine relations between ΔDL CO and the covariables. Results : At baseline, mean [standard deviation (SD)] DL CO was 10.8 (2.4) and 7.8 (1.6) mmol·min −1 ·kPa −1 in men and women, respectively. Mean (SD) ΔDL CO was −0.24 (1.31) mmol·min −1 ·kPa −1 . ΔDL CO was negatively related to baseline age, DL CO , current smoking, and pack years, and positively related to forced expiratory volume in 1 second (FEV 1 ) and weight. Sex, occupational exposure, and educational level were not related to ΔDL CO . Conclusions : In a community sample, more rapid decline in DL CO during 9 years of observation time was related to higher age, baseline current smoking, more pack years, larger weight, and lower FEV 1 . Keywords: diffusion capacity for carbon monoxide; longitudinal change; occupational exposure; socioeconomic status; smoking (Published: 2 September 2016) Citation: European Clinical Respiratory Journal 2016, 3: 31265 - http://dx.doi.org/10.3402/ecrj.v3.31265

An explanatory model of functional exercise capacity in patients with systemic sclerosis: considerations for rehabilitation programs

Abstract: [Purpose] This study aimed to evaluate the impact of lung function and peripheral muscle function on the six-minute walking distance (6MWD) in systemic sclerosis (SS) patients and, thereby, to develop an explanatory model of functional exercise capacity for these individuals. [Methods] In a cross-sectional study, 31 SS patients underwent pulmonary function testing (including spirometry, diffusing capacity for carbon monoxide [DLCO], and respiratory muscle strength), isometric dynamometry with surface electromyography, and the 6MWD. [Results] There was a significant correlation between the 6MWD (% predicted, 6MWD%) and the following parameters: height (r = 0.427) and DLCO (r = 0.404). In contrast, no other independent variable showed a significant correlation with the 6MWD% (r ≤ 0.257). The final prediction model for 6MWD% (adjusted R(2) = 0.456, SE of bias=12%) was 6MWD% Gibbons = -131.3 + 1.16 × heightcm + 0.33 × DLCO% predicted. [Conclusion] In SS patients, body height and pulmonary diffusion are the main determinants of the 6MWD. Our results justify further investigation of the performance of SS patients during exercise, which may increase the understanding of the pathophysiological mechanisms involved in the disease. The impact of these findings in SS patients may be useful for evaluating the effects of rehabilitation programs.

Physiological Aspects of Marathon Running

Abstract: Marathon running has evolved as one of the world’s popular running experiences. Independent of the runner’s performance level the marathon event represent a major challenge to the runner’s biology. Multiple integrated physiological processes operate to resist fatigue during marathon running. The physical preparation for a marathon involves a series of complex biological adaptations to counteract exercise induced fatigue. The following chapter aims at describing important physiological components that are proposed to constrain a champion’s physiological capacity for ultimate endurance performance. Further, potential limiting factors of the lungs, cardio-vascular system, blood oxygen carrying capacity, muscle properties and metabolism are explained in order to understand the underlying mechanisms for developing specific training methods and to estimate the race pace during marathon running. Other important biological aspects involved in marathon running such as nutrition, thermoregulation, biomechanics will be discusses in detail in the following chapters.

Clinical analysis of 43 patients with eosinophilic granulomatosis with polyangiitis

Abstract: Objective To describe the clinical features of eosinophilic granulomatosis with polyangiitis (EGPA). Methods Patients who fulfilled the criteria for EGPA managed at the Beijing Chaoyang Hospital of Capital Medical University between May 2005 and Feb 2014 were retrospectively investigated. Patients' characteristics were compared according to antineutrophil cytoplasmic antibody (ANCA) status.Patients were followed up in outpatient service or by telephone to evaluate the treatment result. Results There were 43 patients included, 24 males and 19 females. Mean age at onset was (53.0±15.0) years old. The most common onset symptom of EGPA was asthma in 30 (69.8%) patients. Asthma was also the most common symptom in 42 (97.7%) patients, followed by sinusitis and rhinitis in 40(93.0%) patients and peripheral neuropathy in 26 (60.5%) patients. ANCA positive was found in 13 (30.2%) patients, mainly anti-myeloperoxidase antibodies. High resolution computed tomography scanning (HRCT) of the chest was performed in all the patients, and the main anomalies included ground-glass opacities in 34 (79.1%) patients and bronchial wall thickening and/or bronchial dilatation in 22 (51.2%) patients. Pulmonary function tests available at diagnosis in 33 patients mainly demonstrated an obstructive ventilatory defect. There were totally 33 patients who underwent biopsy, 21 (63.6%) patients had histologic findings supporting a diagnosis of EGPA, including eosinophil infiltration in 21 patients, vasculitis in 5 patients, but no granuloma. ANCA-positive patients were more likely to have fever and renal disease, more honeycombing pattern in the HRCT image and more significantly decreased pulmonary diffusion function, while ANCA-negative patients were more likely to have significant obstructive ventilatory defect. 41 patients received oral corticosteroids, among them, 19 patients additionally received immunosuppressants. 35 Patients were followed for a median of 30 (13, 46) months, 3 patients died (mortality 8.57%), among the other 32 patients, asthma was still the most common symptom in 16 (50%) patients at their last visit, and prednisone administration had to be continued for 23 (71.9%) patients. Conclusions The clinical manifestations of EGPA may vary widely, and it involves different organs. Physicians should be alert to EGPA when seeing patients with refractory asthma and eosinophilia. Key words: Eosinophilic granulomatosis with polyangiitis; Disease attributes; Antibodies, antineutrophil cytoplasmic; Peroxidase