Is venous blood gas performed in the Emergency Department predictive of outcome during acute on chronic hypercarbic respiratory failure?

Background: During acute on chronic hypercarbic respiratory failure (AHRF), arterial pH is associated with non-invasive ventilation (NIV) failure and mortality. Venous blood gas (VBG) has been proposed as a substitute for arterial blood gas, based on a good agreement between venous and arterial values. We assessed the predictive value of admission VBG on intubation rate, NIV failure and mortality during AHRF.