Arterialised Capillary Blood Gases in Accident and Emergency Department Patients - a Reliable Alternative to Arterial Sampling?

OBJECTIVES: Many patients with respiratory complaints who present to the Accident & Emergency (A & E) department have an arterial blood gas analysis performed at some point. It is our belief that there is no difference between arterial and capillary blood gas values in patients presenting to the A & E department. It is also anticipated that body temperature and blood pressure may play a part, so these will also be reported and associations will be investigated. METHODS: Patients who require arterial blood gas analysis at any stage during their stay in the A & E department at the Northern General hospital of Sheffield are eligible for inclusion in the study. In total there were 32 patients. PROCEDURE:Transvasin cream was applied to the ear lobe to improve local blood flow by dilating the capillaries. When ten minutes have elapsed after the application of the Transvasin cream, a capillary sample is taken from the ear lobe by the researchers. CONCLUSION: From the t-tests conducted, no significant difference was seen between the arterial and capillary blood gas samples for the parameters pO2 and O2 saturation. However, for pCO2, pH and [HCO3] there were significant differences observed. This result seems to disagree with the findings of most other studies that have so far shown stronger correlations generally for pH, pCO2 and bicarbonate, than for oxygen measuring parameters.