TY - JOUR T1 - Orthodeoxia in hypoxaemic morbid obesity reverts one year after bariatric surgery JF - European Respiratory Journal JO - Eur Respir J VL - 40 IS - Suppl 56 SP - P3789 AU - Eva Rivas AU - Ebymar Arismendi AU - Ana Tejedor AU - Yolanda Torralba AU - Concepcion Gistau AU - Felip Burgos AU - Salvadora Delgado AU - Jaume Balust AU - Robert Rodriguez-Roisin Y1 - 2012/09/01 UR - http://erj.ersjournals.com/content/40/Suppl_56/P3789.abstract N2 - Introduction: In morbid obesity (MO), pulmonary gas exchange (GE) abnormalities are influenced by postural changes that are known to improve after bariatric surgery (BS).Objective: To unravel the determinants of GE in MO at upright (U) and supine (S) while breathing ambient air, in random order, before and one year after BS.Methods: 15 (14 females; 51±(SE)2 yrs; BMI, 47±2 Kg/m2) hypoxaemic -H- (PaO2, 73±5 mmHg) and 8 normoxaemic -N- (PaO2, 89±4 mmHg), matched for age, sex and BMI were studied before and after BS. GE measurements, including ventilation-perfusion (V'A /Q') distributions were performed.Results: Before BS, H patients at U exhibited moderate V'A /Q' imbalance (low V'A /Q' areas (<0.1), 10±2% of QT) compared to S. In addition, PaO2 (by –4.1±0.4 mmHg) and PvO2 (by –1.5±0.1 mmHg) diminished (p≤0.04, each) along with a trend to reduce QT (by –0.4±0.1 L/min) (p=0.09) at U. By contrast, N patients did not show GE changes. After BS, BMI decreased in both H and N patients (by 36 % - 37%), and overall PaO2 at U improved (by +15.9±0.2 mmHg), (p≤0.03, each). Moreover, H patients at U improved PaO2 (by +6.7±0.6 mmHg) compared to S and, V'A /Q' imbalance postural differences between Pre- and Post-BS also improved (p ≤0.02).Conclusions: Hypoxaemic morbid obesity is associated with orthodeoxia. This novel finding may be related to a gravitational heterogeneous redistribution of pulmonary blood flow induced by systemic inflammation. Bariatric surgery reverts completely this phenomenon.Supported by FIS (PI08031108), Esteve and CIBERES. ER -