Towards evidence-based emergency medicine: best BETs from the Manchester Royal Infirmary. BET 2: In patients presenting with an exacerbation of COPD can a normal venous blood gas pCO2 rule out arterial hypercarbia?

A shortcut review was carried out to establish whether a normal partial pressure of carbon dioxide (pCO2) on a venous blood sample could be used to rule out hypercarbia. Eleven studies were directly relevant to the question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these papers are tabulated. The clinical bottom line is that a normal venous pCO2 effectively rules out arterial hypercarbia.