Abstract

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 Çukurova 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.