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Nonparametric Methods
Published in Marcello Pagano, Kimberlee Gauvreau, Heather Mattie, Principles of Biostatistics, 2022
Marcello Pagano, Kimberlee Gauvreau, Heather Mattie
Emphysema is a swelling of the air sacs in the lungs that is characterized by labored breathing and an increased susceptibility to infection. Carbon monoxide diffusing capacity, denoted is a measure of lung function that has been tested as a possible diagnostic tool for detecting emphysema. Consider the distributions of CO diffusing capacity for a population of healthy individuals, and a population of patients with emphysema. We are not willing to assume that these distributions follow a normal distribution. Therefore, using a Wilcoxon rank sum test conducted at the level of significance, we evaluate the null hypothesis that the two populations have the same median DlCO.
Interstitial Lung disease In Childhood Rheumatic Disorders
Published in Lourdes R. Laraya-Cuasay, Walter T. Hughes, Interstitial Lung Diseases in Children, 2019
Steen and associates26 followed 44 patients with PSS treated with a mean dose of 636 mg of D-penicillamine for 2.3 years. They compared these patients with 48 untreated patients who had repeat pulmonary function tests. There was a mean of 3.5 years between sets of pulmonary function tests in the treated group and 4.8 years in the untreated group. There were no significant changes in the vital capacity or forced expiratory volumes in either group but there was a small change in diffusing capacity in penicillamine treated patients, from 76 to 87% of the predicted value. Diffusing capacity in untreated patients changed from 73 to 76% of the predicted value. The improvement in treated patients was associated with no further progression of dyspnea or of fibrosis on chest radiograph. The authors concluded that D-penicillamine might be useful in treatment of PSS involving the lung. Other agents including corticosteroids and immunosuppressive drugs have not been shown to alter the pulmonary outcome although corticosteroids occasionally appear to be of short term benefit when there is evidence of inflammatory disease.
Disability and impairment in asbestosis and asbestos-related diffuse pleural disease
Published in Dorsett D. Smith, The Health Effects of Asbestos, 2015
The determination of a diffusing capacity is also dependent on the use of appropriate prediction values. The diffusing capacity rises with elevation. The use of values obtained in Salt Lake City, Utah, which are elevated compared to values obtained near sea level, may produce a false appearance of abnormality. (Smith DD. Pulmonary impairment/disability evaluation: Controversies and criticisms. Clin Pulm Med 1995;2:334–43; Smith DD. What is asbestosis? Chest 1990;98:963–4; American Thoracic Society. ATS/ERS Task Force: Standardisation of lung function testing. Eur Respir J 2005;26:319–38; Hankinson JL, Odencrantz JR, Fedan KB. Spirometric reference values from a sample of the general US population. Am J Respir Crit Care Med 1999;159:179–87.)
Lung function in relation to six-minute walk test in pulmonary hypertension
Published in European Clinical Respiratory Journal, 2020
Amir Farkhooy, Michaela Bellocchia, Hans Hedenström, Daniela Libertucci, Caterina Bucca, Christer Janson, Paolo Solidoro, Andrei Malinovschi
No relation between diffusing capacity for carbon monoxide and walk distance was found in the present material. The diffusing capacity relates inversely to the mean pulmonary arterial pressure and this is in line with results from echocardiography studies, which found no relation between pulmonary arterial pressure and 6MWD [20]. We hypothesize that the patients were characterized as pulmonary hypertensive, e.g. reduced diffusion capacity, makes airway obstruction more influential in the outcome of 6MWT due to a tendency of uniformity for DLCO. This is in fact in line with previous findings from our group in which we could demonstrate that in patients suffering from COPD, e.g. airway obstruction, DLCO is more closely linked to reduced walk distance [38]. On the other hand, DLCO/VA was revealed as the main determinant of exercise-induced desaturation, which is in line with reported interdependence between pulmonary diffusion and oxygen desaturation during exercise in patients with diffuse systemic sclerosis and interstitial lung disease [39].
Automatic oxygen titration with O2matic® to patients admitted with COVID-19 and hypoxemic respiratory failure
Published in European Clinical Respiratory Journal, 2020
Ejvind Frausing Hansen, Charlotte Sandau Bech, Jørgen Vestbo, Ove Andersen, Linette Marie Kofod
Lung function data showed a marked reduction in FEV1, FVC and PEF, all reduced to approximately 50% of predicted, reflecting a substantial loss of lung volume. It was not possible to measure diffusing capacity due to patients having dyspnea and tachypnea, which prevented the breath-holding maneuver. Neither do we have data on lung function before admission with COVID-19, but only three patients had known obstructive lung disease, which makes it unlikely that a severe reduction in dynamic volumes was present before admission. Some patients experienced difficulties in performing spirometry due to acute breathlessness and coughing, and acceptability criteria could not be met for all patients. However, we find it unlikely that low quality of the spirometry accounts for a substantial part of the reduction in FEV1, FVC and PEF. Another study has shown minor reduction in dynamic values at discharge from admission with COVID-19 [19]. Our study was done during the first days after admission, and 93% of the patients had acute radiological abnormalities with infiltrates and interstitial changes which could account for the severely impacted lung function.
Risk factors for impaired pulmonary function and cardiorespiratory fitness in very long-term adult survivors of childhood acute lymphoblastic leukemia after treatment with chemotherapy only*
Published in Acta Oncologica, 2018
Ole Henrik Myrdal, Adriani Kanellopoulos, Jon R. Christensen, Ellen Ruud, Elisabeth Edvardsen, Johny Kongerud, Liv Ingunn Sikkeland, May B. Lund
Pulmonary function tests included dynamic spirometry, determination of static lung volumes and single breath gas diffusing capacity (DLCO). Spirometric variables were forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and the ratio FEV1/FVC. Lung volume variables were total lung volume (TLC) and residual volume (RV). Gas transfer variables were transfer factor for carbon monoxide, DLCO and DLCO divided by alveolar volume, VA. DLCO measurements were also corrected for Hb. All measurements were performed with the Vmax Pulmonary Function Unit (VIASYS Respiratory Care Inc, Yorba Linda, CA) and according to the guidelines recommended by the European Respiratory Society guidelines (ERS) [26–28]. The pulmonary function variables were expressed in absolute values and as a percentage of predicted normal values. Reference values were those recommended by ERS [29]. Obstructive impairment was defined as FEV1/FVC <0.7 according to The Global Initiative for Chronic Obstructive Lung Disease [30]. Restrictive impairment and impairment in DLCO were defined as <80% of predicted. These cutoff points correspond to the lower 5th percentiles in the reference material and in line with ERS recommendations [29].