Calculating acid-base and oxygenation status during COPD exacerbation using mathematically arterialised venous blood.

Background: Repeated arterial puncture is painful. A mathematical method exists for transforming peripheral venous pH, PCO 2 and PO 2 to arterial eliminating the need for arterial sampling. This study evaluates this method to monitor acid base and oxygenation during admission for exacerbation of chronic obstructive pulmonary disease (COPD).