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We hypothesised that the airway resistance during tidal breathing would correlate with a particular pattern of increasing obesity, particularly when supine, and would differ between participants with and without ventilatory failure.In our cross-sectional cohort study, 72 morbidly obese patients (40 males, 32 females, mean body mass index (BMI) 47.2) had measurements of both airways resistance (by impulse oscillometry (IOS)) and adiposity (by dual-energy X-ray absorptiometry (DXA)).All measures of airways resistance increased in the supine position: total airways resistance (R5) +37% (p<0.0005); large airways resistance (R20) +29% (p<0.0005); and small airways resistance (R5-R20) +52% (p<0.0005). BMI was correlated with seated R5, seated R5-R20, supine R5 and supine R5-R20 (r=0.33 p<0.006, r=0.32 p<0.004, r=0.30 p<0.02 and r=0.36 p<0.04, respectively). Visceral adipose tissue mass was correlated with supine R5-20 (r=0.46 p<0.05). Supine measures of total airways resistance (R5) and large airways resistance (R20) differed between those with and without ventilatory failure, as did mean weight and BMI.Our study identifies a potentially detrimental effect of the supine posture on tidal breathing airways resistance in obese patients. This change is correlated most with visceral adipose tissue mass and the small airways. We were able to demonstrate that supine increases in airways resistance during tidal breathing, within obese patients, are different between those with and without ventilatory failure.NCT01380418; pre-results.

Original publication

DOI

10.1136/bmjresp-2016-000138

Type

Journal article

Journal

BMJ open respiratory research

Publication Date

09/06/2016

Volume

3

Pages

e000138 - e000138

Addresses

Oxford Respiratory Trials Unit, Experimental Medicine Division, Nuffield Department of Medicine, University of Oxford, Oxford, UK; St Peter's College, New Inn Hall Street, Oxford, UK; Centre for Altitude, Space and Extreme Environment Medicine (CASE Medicine), Institute of Sport Exercise and Health, University College London, London, UK.