What factors influence arterial blood gas sampling patterns?

STUDY OBJECTIVE: To investigate if patterns of arterial blood gas (ABG) sampling were influenced by values of fractional inspiratory oxygen (FiO2), partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2) and oxygen saturation (%SaO2). SETTING: An intensive care unit (ICU) in a university teaching hospital located in the North of England, UK. DESIGN: A retrospective, descriptive, correlation study based on patient records. PARTICIPANTS: All patients admitted to the ICU for 24 hours or greater and who had an arterial line in situ. MEASUREMENTS AND RESULTS: The study included the records of 65 patients consecutively admitted to the ICU. Patients in this study had more blood gases taken than reported elsewhere in the literature. While consistent correlation was found between values of FiO2, PCO2, PO2 and %SaO(2), values of PO2 were the most consistent. CONCLUSIONS: Values of PO2 are associated with frequency of ABG sampling and to a lesser extent on FiO2. Nurses in this study opted to track changes in oxygenation using ABGs despite continuous monitoring of %SaO2.