Controlled oxygen therapy and carbon dioxide retention during exacerbations of chronic obstructive pulmonary disease

Hypoxaemic patients with exacerbations of chronic obstructive pulmonary dis ease (COPD) are at some risk of carbon dioxide (CO2) retention during oxyge n therapy. We quantified the risk of CO2 retention with oxygen therapy in C OPD In 24 consecutive patients presenting to the accident and emergency dep artment with acute exacerbations associated with hypercapnic respiratory fa ilure (partial arterial pressure of oxygen [PaO2] <8 kPa and partial pressu re of CO2 [PaCO2] <greater than or equal to>6.5 kPa). Only three patients d eveloped clinically important CO2 retention (defined as a rise in PaCO2 >1 kPa) with controlled oxygen therapy (24-40% by Venturi mask to maintain the oxygen saturation at 91-92%), These patients presented with more severe hy percapnia, but all three required only low-flow oxygen (24-28%). these find ings suggest only a small risk of aggravating hypercapnia with controlled o xygen supplementation.