title: Predicting nocturnal hypoventilation in hypercapnic chronic obstructive pulmonary disease patients undergoing long-term oxygen therapy.
abstract: BACKGROUND
  Chronic obstructive pulmonary disease (COPD) patients are very sensitive to changes in pulmonary mechanics and central ventilation control during sleep and may develop significant gas exchange alterations with increased hypoxemia and hypercapnia. Oxygen therapy improves nocturnal desaturation but can worsen hypoventilation.
  
  
  OBJECTIVE
  To analyze the prevalence of nocturnal hypoventilation (NHV) in hypercapnic COPD patients and to determine predictive factors for this phenomenon.
  
  
  METHODS
  This was a prospective multicenter study which enrolled 80 clinically stable COPD patients with hypercapnic respiratory failure who fulfilled the conventional criteria for long-term oxygen therapy (LTOT). All patients had undergone pulmonary function testing, blood gas analysis, and respiratory polygraphy. Arterial blood gas samples were obtained while patients were awake and during sleep. NHV was considered when an increase in PaCO2 >10 mm Hg was observed in any nocturnal arterial blood gas sample as compared to the awake levels.
  
  
  RESULTS
  Seventeen patients (21%) developed NHV. NHV was associated with the values of BMI, hemoglobin, hematocrits, DLCO, and PaO2 reached after oxygen administration. In the logistic regression analysis BMI (OR 1.26, 95% CI 1.068-1.481; p = 0.006) and the diurnal increase of PaO2 after O2 (OR 0.89, 95% CI 0.807-0.972; p = 0.010) were the variables that best discriminated with a sensitivity of 82% and a specificity of 78%.
  
  
  CONCLUSIONS
  NHV is a relatively common finding in stable hypercapnic COPD patients undergoing LTOT and it is related to a higher BMI and lower PaO2 after oxygen administration.
authors.affiliation: Respiratory Medicine, Hospital General de Granollers, Granollers, Spain. 30778jtc @ comb.cat
authors.forename: Julia
authors.initials: J
authors.lastname: Tarrega
authors.forename: Antonio
authors.initials: A
authors.lastname: Anton
authors.forename: Rosa
authors.initials: R
authors.lastname: Guell
authors.forename: Mercedes
authors.initials: M
authors.lastname: Mayos
authors.forename: Daniel
authors.initials: D
authors.lastname: Samolski
authors.forename: Sergi
authors.initials: S
authors.lastname: Marti
authors.forename: Eva
authors.initials: E
authors.lastname: Farrero
authors.forename: Enric
authors.initials: E
authors.lastname: Prats
authors.forename: Joaquin
authors.initials: J
authors.lastname: Sanchis
mesh_terms: D000368:Aged; D001158:Arteries; D015992:Body Mass Index; D002940:Circadian Rhythm; D006801:Humans; D006935:Hypercapnia / Q000150:complications / Q000209:etiology*; D007040:Hypoventilation / Q000453:epidemiology / Q000209:etiology*; D016015:Logistic Models; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010102:Oxygen Inhalation Therapy / Q000009:adverse effects*; D015995:Prevalence; D011379:Prognosis; D011446:Prospective Studies; D011650:Pulmonary Alveoli / Q000098:blood supply; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000473:pathology / Q000628:therapy*; D012131:Respiratory Insufficiency / Q000209:etiology; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D010100:Oxygen