Pulmonary Vascular Congestion: A Mechanism for Distal Lung Unit Dysfunction in Obesity

• Published in: PloS one 2016-04, Vol.11 (4), p.e0152769-e0152769
• Main Authors: Oppenheimer, Beno W, Berger, Kenneth I, Ali, Saleem, Segal, Leopoldo N, Donnino, Robert, Katz, Stuart, Parikh, Manish, Goldring, Roberta M
• Format: Article
• Language: English
• Subjects: Abnormalities; Adult; Airway obstruction; Alveoli; Asthma; Biology and Life Sciences; Blood; Blood volume; Body mass; Cardiac output; Cardiology; Complications and side effects; Computing time; Congestion; Critical care; Diffusion; Disease; Edema; Female; Gastrointestinal surgery; Heart; Heart diseases; Heart failure; Hospitals; Humans; Laboratories; Lung - blood supply; Lung - physiopathology; Lungs; Magnetic resonance imaging; Male; Medicine; Medicine and Health Sciences; Membranes; Middle Aged; Obesity; Obesity - complications; Obesity - physiopathology; Permeability; Physiology; Recruitment; Research and Analysis Methods; Respiratory tract; Risk factors; Sleep; Smoking; Spirometry; Surface area; Weight control
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0152769

Obesity is characterized by increased systemic and pulmonary blood volumes (pulmonary vascular congestion). Concomitant abnormal alveolar membrane diffusion suggests subclinical interstitial edema. In this setting, functional abnormalities should encompass the entire distal lung including the airways. We hypothesize that in obesity: 1) pulmonary vascular congestion will affect the distal lung unit with concordant alveolar membrane and distal airway abnormalities; and 2) the degree of pulmonary congestion and membrane dysfunction will relate to the cardiac response. 54 non-smoking obese subjects underwent spirometry, impulse oscillometry (IOS), diffusion capacity (DLCO) with partition into membrane diffusion (DM) and capillary blood volume (VC), and cardiac MRI (n = 24). Alveolar-capillary membrane efficiency was assessed by calculation of DM/VC. Mean age was 45±12 years; mean BMI was 44.8±7 kg/m2. Vital capacity was 88±13% predicted with reduction in functional residual capacity (58±12% predicted). Despite normal DLCO (98±18% predicted), VC was elevated (135±31% predicted) while DM averaged 94±22% predicted. DM/VC varied from 0.4 to 1.4 with high values reflecting recruitment of alveolar membrane and low values indicating alveolar membrane dysfunction. The most abnormal IOS (R5 and X5) occurred in subjects with lowest DM/VC (r2 = 0.31, p