Correlation of simultaneously obtained capillary, venous, and arterial blood gases of patients in a paediatric intensive care unit.

AIMS: To investigate the correlation of pH, partial pressure of oxygen (PO2), partial pressure of carbon dioxide (PCO2), base excess (BE), and bicarbonate (HCO3) between arterial (ABG), venous (VBG), and capillary (CBG) blood gases.
METHODS: Patients admitted to the paediatric intensive care unit (PICU) in Cukurova University between August 2000 and February 2002 were enrolled.
RESULTS: A total of 116 simultaneous venous, arterial, and capillary blood samples were obtained from 116 patients (mean age 56.91 months, range 15 days to 160 months). Eight (7%) were neonates. Sixty six (57%) were males. pH, PCO2, BE, and HCO3 were all significantly correlated in ABG, VBG, and CBG. Correlation in PO2 was also significant, but less so. Correlation between pH, PCO2, PO2, BE, and HCO3 was similar in the presence of hypothermia, hyperthermia, and prolonged capillary refilling time. In hypotension, correlation in PO2 between VBG and CBG was similar but disappeared in ABG-VBG and ABG-CBG.
CONCLUSIONS: There is a significant correlation in pH, PCO2, PO2, BE, and HCO3 among ABG, VBG, and CBG values, except for a poor correlation in PO2 in the presence of hypotension. Capillary and venous blood gas measurements may be useful alternatives to arterial samples for patients who do not require regular continuous blood pressure recordings and close monitoring of PaO2. We do not recommend CBG and VBG for determining PO2 of ABG.