title: Frequency and predictors of obesity hypoventilation in hospitalized patients at a tertiary health care institution.
abstract: OBJECTIVE
  Patients with obesity hypoventilation syndrome (OHS) have significant morbidity and mortality. Early diagnosis and treatment is important and there are limited data on its prevalence and predictive factors. The objective of this observational study was to determine the frequency and predictors of OHS in hospitalized patients at a tertiary health care institution.
  
  
  METHODS
  All blood gas analyses of hospitalized adult (age over 18 years) patients were prospectively recruited from the biochemistry laboratory at a tertiary health care center between August 2009 and July 2010. Patients who had hypercapnia (PaCO2 ≥ 45 mmHg) while breathing room air were included and clinical and laboratory data were obtained from hospital records. A standard questionnaire was also filled by face-to-face interview with patients and/or relatives.
  
  
  RESULTS
  A total of 9480 patients' arterial blood gases were evaluated and 330 patients (3.4%) who met the selection criteria were included in the analysis during the study period. Hypoventilation was associated with acute diseases in 64.2% and chronic diseases in 35.8% of the patients. Of the chronic hypoventilation patients, 24.4% had OHS. Univariate logistic regression analysis showed that, female gender, body mass index (BMI), smoking, PaO2, SaO2 and a PaCO2/BMI <1.5 were significantly related to OHS. In multivariate logistic regression analysis, BMI >35 kg/m(2), SaO2 <91.4% and PaCO2 /BMI <1.5 were significantly related to OHS. A PaCO2/BMI <1.5 was an independent variable strongly predictive of OHS (odds ratio: 36.9, 95% of the confidence interval: 2.75-492.95, P = 0.007).
  
  
  CONCLUSIONS
  OHS is a common cause of chronic alveolar hypoventilation. A careful examination PaCO2 /BMI ratio may prevent misdiagnoses among hypercapnic patients.
authors.affiliation: Department of Chest Diseases, School of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Yilmaz
authors.initials: Y
authors.lastname: Bülbül
authors.affiliation: Department of Chest Diseases, School of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Sibel
authors.initials: S
authors.lastname: Ayik
authors.affiliation: Department of Chest Diseases, School of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Tevfik
authors.initials: T
authors.lastname: Ozlu
authors.affiliation: Department of Biochemistry, School of Medicine, Karadeniz Technical University, Trabzon, Turkey.
authors.forename: Asim
authors.initials: A
authors.lastname: Orem
keywords: Hypercapnia; hypoventilation; obesity hypoventilation syndrome; respiratory failure