How Successful is Non-Invasive Ventilation Treatment that is Initiated in the Emergency Department in Cases of COPD Exacerbations with Acute Hypercapnic Respiratory Failure? Can We Predict Treatment Failure?

Objective: We aimed to investigate the success rate of non-invasive ventilation (NIV) in wards and the predictors of failure in cases of chronic obstructive pulmonary disease (COPD)-related acute hypercapnic respiratory failure (AHRF).
Methods: The was a retrospective study conducted in a tertiary teaching hospital between May 2011 and 2013. Patients who were admitted to the emergency department (ED) because of COPD with AHRF were evaluated; 544 patients who initially received NIV in ED and were transferred to wards were included. Patient characteristics, baseline and follow-up pH values, and partial arterial carbon dioxide (PaCO2) values were recorded. Baseline pH values were categorized as severe (pH<7.26), moderate (pH≥7.26–7.30), and mild (pH≥7.30) acidosis. According to the in-hospital outcome, patients were classified in 2 groups: Group 1: home discharge, Group 2: death or intensive care unit transfer.
Results: Treatment resulted in success in 477 (88%) patients. Albumin levels were significantly low and the mean Charlson index (CI) score was significantly high in Group 2. Admission pH and PaCO2 values did not affect the treatment outcome. Patients in Group 2 had higher PaCO2 and lower pH values as well as a lower level of decrease in PaCO2 values within 2 hours of treatment in ED. Similarly, higher PaCO2 and lower pH values at the end of the first day in wards were indicative of NIV failure (p<0.05).
Conclusion: The success rate of NIV in wards in cases of AHRF is high. Patients with low albumin levels and higher CI scores have worse response to treatment. pH or PaCO2 values after a few hours of treatment and not the baseline pH or PaCO2 values are better predictors than the baseline pH and PaCO2 values.