From the Research
An O2 level of 74 mmHg on a venous blood gas (VBG) is within the normal range for venous blood, as established by a recent study 1, which defined the reference interval for partial pressure of oxygen (pO2) in venous blood as 19-65 mmHg. This finding suggests that the peripheral tissues are extracting oxygen efficiently from arterial blood. When interpreting this result, it is essential to consider the patient's overall clinical condition and other hemodynamic parameters. The reference interval for VBG measurements was established in a study of 151 adult volunteers 1, which provides a reliable basis for interpreting VBG results. In the context of cardiac output, a normal venous oxygen level like 74 mmHg may indicate adequate cardiac function, but it is crucial to correlate this finding with other clinical parameters, such as echocardiography or cardiac output measurements, to confirm cardiac function. Other causes of normal venous oxygen levels include adequate oxygen delivery and utilization by peripheral tissues. Clinical correlation with other hemodynamic parameters and the patient's overall condition is essential for proper interpretation of VBG results, as emphasized in a study comparing central venous blood gas to arterial blood gas 2. It is also important to note that VBG analysis is becoming a popular alternative to arterial blood gas (ABG) analysis due to reduced risk of complications at phlebotomy and ease of draw, as discussed in a narrative review 2. However, the relationship between ABGs and central VBGs in critically ill patients is complex, and further evaluation is necessary to determine the utility of central VBG in guiding clinical decisions 2. In summary, an O2 level of 74 mmHg on a VBG is within the normal range, but its interpretation requires careful consideration of the patient's clinical condition and other hemodynamic parameters.
Some key points to consider when interpreting VBG results include:
- The reference interval for pO2 in venous blood is 19-65 mmHg 1
- VBG analysis is a useful alternative to ABG analysis in certain clinical situations 2
- Clinical correlation with other hemodynamic parameters and the patient's overall condition is essential for proper interpretation of VBG results 2
- The relationship between ABGs and central VBGs in critically ill patients is complex and requires further evaluation 2