Blood oximetry provides a fundamental approach to blood gases for inpatients. Arterial blood gases (ABG) have been considered the gold standard for blood oximetry assessment. Venous blood gas (VBG) evaluation is frequently available and provides a source of a more comfortable method for the assessment of blood oximetry in pediatric patients. Some data provided by the venous blood gas can be additive and offer insights apart from the arterial blood gas. The purpose of this review is to provide an assessment of the performance of VBG in pediatric patients. The study concludes that VBG are helpful tools in assessing oxygenation and ventilation in critically ill children and can be used as a marker of adequacy of systemic oxygen delivery. In the setting of systemic oxygen delivery decrease or oxygen extraction increase, the partial pressure of oxygen on the VBG will decrease. Thus, the partial pressure of oxygen and the corresponding venous saturation can be a marker of systemic oxygen delivery in a variety of illnesses. Simultaneous ABG and VBG comparison can actually lend great insight to not only the respiratory status of a patient but provide an assessment of the adequacy of cardiac output and systemic oxygen delivery.