title: Ventilation/Perfusion distribution abnormalities in morbidly obese subjects before and after bariatric surgery.
abstract: BACKGROUND
  Obesity is a global and growing public health problem. Bariatric surgery (BS) is indicated in patients with morbid obesity. To our knowledge, the effects of morbid obesity and BS on ventilation/perfusion (V.a/Q.) ratio distributions using the multiple inert gas elimination technique have never before been explored.
  
  
  METHODS
  We compared respiratory and inert gas (V.a/Q. ratio distributions) pulmonary gas exchange, breathing both ambient air and 100% oxygen, in 19 morbidly obese women (BMI, 45 kg/m2), both before and 1 year after BS, and in eight normal-weight, never smoker, age-matched, healthy women.
  
  
  RESULTS
  Before BS, morbidly obese individuals had reduced arterial Po2 (76 ± 2 mm Hg) and an increased alveolar-arterial Po2 difference (27 ± 2 mm Hg) caused by small amounts of shunt (4.3% ± 1.1% of cardiac output), along with abnormally broadly unimodal blood flow dispersion (0.83 ± 0.06). During 100% oxygen breathing, shunt increased twofold in parallel with a reduction of blood flow to low V.a/Q. units, suggesting the development of reabsorption atelectasis without reversion of hypoxic pulmonary vasoconstriction. After BS, body weight was reduced significantly (BMI, 31 kg/m2), and pulmonary gas exchange abnormalities were decreased.
  
  
  CONCLUSIONS
  Morbid obesity is associated with mild to moderate shunt and V.a/Q. imbalance. These abnormalities are reduced after BS.
authors.affiliation: Servei d'Anestesiologia, University of California, San Diego (UCSD), San Diego, CA; Institut d'investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) and Fundació Clínic per a la Recerca Biomédica (FCRB), University of California, San Diego (UCSD), San Diego, CA.
authors.forename: Eva
authors.initials: E
authors.lastname: Rivas
authors.affiliation: Institut d'investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) and Fundació Clínic per a la Recerca Biomédica (FCRB), University of California, San Diego (UCSD), San Diego, CA; CIBER Enfermedades Respiratorias (CIBERES), University of California, San Diego (UCSD), San Diego, CA.
authors.forename: Ebymar
authors.initials: E
authors.lastname: Arismendi
authors.affiliation: Institut d'investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) and Fundació Clínic per a la Recerca Biomédica (FCRB), University of California, San Diego (UCSD), San Diego, CA; Servei de Pneumologia (Institut Clínic del Tòrax [ICT]), University of California, San Diego (UCSD), San Diego, CA; CIBER Enfermedades Respiratorias (CIBERES), University of California, San Diego (UCSD), San Diego, CA.
authors.forename: Alvar
authors.initials: A
authors.lastname: Agustí
authors.affiliation: Institut d'investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) and Fundació Clínic per a la Recerca Biomédica (FCRB), University of California, San Diego (UCSD), San Diego, CA; Centre de Diagnòstic per la Imatge (CDI), University of California, San Diego (UCSD), San Diego, CA.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Sanchez
authors.affiliation: Institut d'investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) and Fundació Clínic per a la Recerca Biomédica (FCRB), University of California, San Diego (UCSD), San Diego, CA; Servei de Cirurgia Gastrointestinal, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Salvadora
authors.initials: S
authors.lastname: Delgado
authors.affiliation: Servei de Pneumologia (Institut Clínic del Tòrax [ICT]), University of California, San Diego (UCSD), San Diego, CA; CIBER Enfermedades Respiratorias (CIBERES), University of California, San Diego (UCSD), San Diego, CA.
authors.forename: Concepción
authors.initials: C
authors.lastname: Gistau
authors.affiliation: Department of Medicine, University of California, San Diego (UCSD), San Diego, CA.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Wagner
authors.affiliation: Institut d'investigacions Biomèdiques August Pi i Sunyer (IDIBAPS) and Fundació Clínic per a la Recerca Biomédica (FCRB), University of California, San Diego (UCSD), San Diego, CA; Servei de Pneumologia (Institut Clínic del Tòrax [ICT]), University of California, San Diego (UCSD), San Diego, CA; CIBER Enfermedades Respiratorias (CIBERES), University of California, San Diego (UCSD), San Diego, CA. Electronic address: rororo@clinic.ub.es.
authors.forename: Roberto
authors.initials: R
authors.lastname: Rodriguez-Roisin
mesh_terms: D050110:Bariatric Surgery; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008168:Lung / Q000503:physiopathology*; D008875:Middle Aged; D009767:Obesity, Morbid / Q000097:blood / Q000503:physiopathology* / Q000601:surgery; D010100:Oxygen / Q000097:blood; D011446:Prospective Studies; D012119:Respiration; D014692:Ventilation-Perfusion Ratio / Q000502:physiology*
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen