title: Predicting survival following non-invasive ventilation for hypercapnic exacerbations of chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Non-invasive ventilation (NIV) has revolutionised the management of hypercapnic exacerbations of chronic obstructive pulmonary disease (COPD). We wished to evaluate factors related to its overall success in the 'real-life' setting.
  
  
  METHODS
  A retrospective analysis of patients receiving NIV for a hypercapnic exacerbation of COPD was performed. Demographics, laboratory data, blood gases and outcomes (hospital discharge or in-patient death) were extracted and subsequently analysed to identify factors relating to its overall success or failure.
  
  
  RESULTS
  Over 6 years, 240 patients (mean age 70 years), received NIV with mean pH and pCO(2) prior to NIV 7.24 and 10.4kPa respectively; of these, 167 survived to hospital discharge with a median age (70 vs. 74; p = 0.02) lower than non-survivors. Absolute values of pH and pCO(2) (higher and lower respectively) prior to NIV and at 1 h were both associated with successful hospital discharge. An improvement (p = 0.02) in pH within an hour of receiving NIV - but not pCO(2) - was associated with surviving to hospital discharge. Of all laboratory data assessed, only baseline urea was significantly (p = 0.021) associated with a successful outcome.
  
  
  CONCLUSIONS
  Younger patients with a lower urea, higher pH and lower pCO(2) at baseline and who demonstrate an improvement in pH within 1 h, are more likely to have a successful outcome when given NIV for a hypercapnic exacerbation of COPD on an unselected basis. Prospective studies evaluating many other parameters are now required to help identify patients in whom NIV is likely to be successful.
authors.affiliation: Chest Clinic C, Aberdeen Royal Infirmary, Aberdeen, UK.
authors.forename: D
authors.initials: D
authors.lastname: Miller
authors.forename: K
authors.initials: K
authors.lastname: Fraser
authors.forename: I
authors.initials: I
authors.lastname: Murray
authors.forename: G
authors.initials: G
authors.lastname: Thain
authors.forename: G P
authors.initials: GP
authors.lastname: Currie
mesh_terms: D000368:Aged; D002245:Carbon Dioxide / Q000097:blood; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000628:therapy*; D008875:Middle Aged; D010313:Partial Pressure; D011175:Positive-Pressure Respiration / Q000401:mortality*; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000401:mortality / Q000628:therapy*; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D002245:Carbon Dioxide