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Chronic respiratory failure – pathophysiology
Published in Claudio F. Donner, Nicolino Ambrosino, Roger S. Goldstein, Pulmonary Rehabilitation, 2020
Mafalda Vanzeller, Marta Drummond, João Carlos Winck
Body plethysmography allows static pulmonary volumes evaluation, measuring residual volume (RV − air volume that remains in the lungs after full expiration), vital capacity (VC − maximum volume expired after a full inspiration or inspired after a full expiration) and total lung capacity (TLC − volume of air in the lungs after full inspiration; the sum of VC and RV). Performing body plethysmography, subjects should be sitting within a large air-tight chamber and make gentle breathing efforts against a shutter, which closes the airway at the mouth. Since the pressure within the rigid plethysmograph changes as lung volume changes according to Boyle's law (pressure × volume = a constant), this allows calculation of thoracic gas volume, from which total lung capacity and residual volume are derived by full inspiration and expiration immediately on opening the shutter. This method measures the volume of any air spaces within or without the lung, which share pressure changes during breathing efforts, so that poorly ventilated (or even totally unventilated, such as a bulla) areas of lung are included.
The Respiratory System and Its Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
Body plethysmography, using a pneumotachometer, is another diagnostic technique used to measure airway mechanics, although this procedure is primarily used only in research laboratories. The specific airway conductance (SGAW) can be determined by this method.
Static lung volumes and lung volume subdivisions
Published in Jonathan Dakin, Mark Mottershaw, Elena Kourteli, Making Sense of Lung Function Tests, 2017
Jonathan Dakin, Mark Mottershaw, Elena Kourteli
By contrast, whole-body plethysmography measures all the gas present within the thoracic cavity which is subject to the pressure changes of the closed-shutter panting manoeuvre. This includes any gas trapped behind closed airways and bullae (Figure 7.4), but may also include intestinal gas. This leads to an overestimate of TLC, although error is not usually large. In those with severe obstruction, changes in lung compliance may also interfere with accurate pressure transmission from the lungs to the mouth during the panting manoeuvre. Nonetheless, measurement of static lung volumes by whole-body plethysmography in obstructive airways disease is more accurate than that measured by gas dilution or washout techniques.
Predictors of methacholine challenge testing results in subjects without airflow obstruction
Published in Journal of Asthma, 2022
Stephanie Chevrier,, Joseph Abdulnour,, Mathieu D. Saint-Pierre,
The mean FEV1% predicted in our cohort was 97% (range 68% to 151% predicted), while the mean FVC % predicted was 103% (range 62% to 176% predicted). Post-bronchodilator testing was performed in 77% of the study population with a significant improvement of the FEV1, defined by most asthma position statements as a change of minimum 12% and 200 ml, seen in 33 subjects (3.8%) (1–3). Only 6 patients (0.7%) had at least 12% and 200 ml improvement of the FVC post-bronchodilator. Approximately 71% had body plethysmography results available and 75% underwent DLCO measurements. Lower FEV1% predicted, reduced forced expiratory flow at 25–75% of the FVC (FEF25%-75%) % predicted, and greater FEF25%-75% reversibility were associated with MCT results. There was also a correlation present between positive FEV1 bronchodilator response and abnormal MCT. Almost half of the subjects with this finding, however, had negative MCT. Peak expiratory flow rate (PEFR) % predicted appeared to have a borderline significant relationship by point-biserial correlation method. Total lung capacity (TLC) % predicted and DLCO % predicted were not linked with MCT results. Very few patients had evidence of gas trapping on lung volume measurements. Interestingly, lower residual volume (RV) % predicted or RV/TLC ratio significantly reduced the probability of AHR. Airway resistance measurements above the upper limit of normal (ULN) were strongly associated with abnormal MCT (Tables 2 and 3).
Canadian lung tissue biobank with associated clinical data supporting respiratory research for four decades
Published in Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 2022
D. P. Sutherland, D. M. Vasilescu, E. T. Osei, N. E. Coxson, C. X. Yang, S. Booth, H. O. Coxson, W. M. Elliot, P. D. Paré, J. C. Hogg, T. L. Hackett
Clinical and physiological data entered into the registry include demographics, lung function, blood cell counts, blood chemistry and imaging studies performed in the days preceding the lung surgery as a standard of care. In some cases, additional research-specific pre-operative tests are performed including body plethysmography, cardiopulmonary exercise testing and heart catheterization. The patients are also interviewed about their medical, smoking and occupational history.14 The data collected includes; age, sex, height, weight, ethnicity, symptoms of cough, phlegm, hemoptysis, wheeze, shortness of breath, co-morbidities, the parent or sibling allergy and asthma, smoking history, smoke exposure in the home, occupational history and exposures, medications and the presentation of the lung problems indicating surgery. Donors’ privacy and the confidentiality of data are preserved at all times. To protect patient confidentiality, all donated lung tissues to the registry are assigned a unique, de-identified registry barcode and data are then stored in an encrypted database. The JHLR adheres to best practices for sample collection, preservation, storage and distribution recommended by The Canadian Tissue Repository Network.15
Role of angiotensin II type 1 (AT1) and type 2 (AT2) receptors in airway reactivity and inflammation in an allergic mouse model of asthma
Published in Immunopharmacology and Immunotoxicology, 2019
Mehaben Patel, Mangesh Kurade, Sahith Rajalingam, Riya Bhavsar, S. Jamal Mustafa, Dovenia S. Ponnoth
We first assessed airway responsiveness by using whole body plethysmography. While the use of whole body plethysmography is controversial, it has been used previously by several investigators either alone [32,33] or in conjunction with invasive techniques [34,35], and continues to be used to assess airway responsiveness [36–39]. In this study, we measured airway responsiveness as enhanced pause (Penh) using increasing doses of MCh to determine the effects of losartan, novokinin and PD 123319 in order to establish the roles of AT1 and AT2 receptors in asthma. Significant increases in Penh values were observed in asthmatic mice compared to non-asthmatic controls, suggesting increases in airway responsiveness in the allergen-sensitized mice. Treatment of losartan in vivo in asthmatic mice significantly reduced airway hyperreactivity compared to allergen-sensitized group suggesting that losartan maybe beneficial to lower airway responsiveness. This also indicates that activation of AT1 receptors in asthma may lead to higher bronchoconstriction. Groups treated with novokinin also displayed similar results as losartan, indicating a beneficial role for AT2 agonist novokinin in asthma. PD 123319, which blocks AT2 receptors, had maximum Penh values, suggesting that blocking of AT2 receptors leads to exacerbation of airway responsiveness. These data suggest that AT2 receptors may be potential targets for reduction of bronchoconstriction in asthma patients and is a novel finding.