Can the Lung be Obese? The Effects of Bariatric Surgery on Lung Function and Imaging

Abstract

Obesity is a state of low-grade chronic systemic inflammation that induces a reduction of adiponectin production with inhibition of the vasorelaxant properties of perivascular adipose tissue with underlying widespread endothelial dysfunction. This review concentrates on the main pulmonary and non-pulmonary determinants of gas exchange abnormalities, characterized by mild-to-moderate increased alveolar-arterial O 2 difference, with or without mild hypoxaemia, in non-smoking morbidly obese subjects without associated relevant co-morbidities, candidates to bariatric surgery, induced by ventilation-perfusion imbalance and increased intrapulmonary shunt, including the effects of 100% oxygen breathing and those induced by postural changes. Likewise, we review lung imaging abnormalities, more specifically lung tissue volume, and their interaction with gas exchange disturbances. Finally, we address the long-term beneficial effects of bariatric surgery on all these obesity-induced lung function and imaging defects. Overall, we present a compelling evidence of lung function and imaging abnormalities underlying systemic and pulmonary inflammation in morbidly obese candidates to bariatric surgery. (BRN Rev. 2018;4:53-66)