Predicting survival following non-invasive ventilation for hypercapnic exacerbations of chronic obstructive pulmonary disease

Int J Clin Pract. 2012 May;66(5):434-7. doi: 10.1111/j.1742-1241.2012.02904.x.


Introduction: 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.

Conclusion: 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.

MeSH terms

  • Aged
  • Carbon Dioxide / blood
  • Humans
  • Hydrogen-Ion Concentration
  • Hypercapnia / therapy*
  • Middle Aged
  • Partial Pressure
  • Positive-Pressure Respiration / mortality*
  • Pulmonary Disease, Chronic Obstructive / blood
  • Pulmonary Disease, Chronic Obstructive / mortality
  • Pulmonary Disease, Chronic Obstructive / therapy*
  • Retrospective Studies
  • Survival Analysis
  • Treatment Outcome


  • Carbon Dioxide