Raveling T, et al. - Researchers investigated predictors for the change in arterial partial pressure of carbon dioxide (PaCO₂) and survival in a cohort of hypercapnic COPD patients treated with chronic noninvasive ventilation (NIV) by using multivariate linear and Cox regression models, respectively. They looked for parameters related to an improved PaCO₂ and survival via 240 COPD patients treated with chronic NIV. An improvement in hypercapnia was seen in patients with anxiety symptoms and a high bicarbonate level at NIV initiation. In addition, a larger reduction in PaCO₂ was seen in relation to higher inspiratory ventilator pressures. However, hypercapnia improvement was not related to improved survival, highlighting the necessity of looking past PaCO₂ when considering NIV initiation. An independent link with better survival higher was seen with body mass index, a higher FEV1, a lower bicarbonate before NIV initiation, and younger age and NIV initiation in stable condition.