Validity of venous blood gas analysis for diagnosis of acid-base imbalance in children admitted to pediatric intensive care unit

Background: Arterial blood gas (ABG) analysis is the major tool for proper diagnosis and treatment of acid-base imbalance, but the invasive nature of arterial puncture and its possible hazards such as arterial spasm have resulted in a worldwide trend toward less-invasive diagnostic methods including venous blood gas (VBG) analysis. This study aimed to evaluate the validity of VBG and its clinical agreement with ABG in the 10 most common diseases in pediatric intensive care unit (PICU), and to answer how far it can replace the ABG test. Methods: In a cross-sectional analytical study from September 2004 to September 2005, 200 patients in 10 disease categories received blood gas analysis. Results of blood-gas tests such as pH, PCO2 and HCO3 of both arterial and venous blood samples (simultaneously taken from each patient) were recorded and compared by statistical analysis (kappa statistics) to determine their validity and clinical agreement. Results: In some diseases such as respiratory distress syndrome, neonatal sepsis, renal failure, pneumonia, diabetic ketoacidosis and status epilepticus, VBG analysis showed a good validity (high sensitivity and specificity) accompanied by a suitable clinical agreement (over 40%), but in other diseases such as neonatal seizure, shock, congestive heart failure and congenital heart disease, there was either an inappropriately low validity or a weak clinical agreement (under 20%). Conclusions: VBG can be used instead of ABG in some diseases such as respiratory distress syndrome, neonatal sepsis, renal failure, pneumonia, diabetic ketoacidosis and status epilepticus, but in other diseases such as neonatal seizure, shock, congestive heart failure and congenital heart diseases, ABG is preferable and must not be replaced by VBG. These results may be used for the formulation of future guidelines for PICU.