Can Venous blood gas be a reliable substitute for Arterial blood gas in modern clinical practice?

Sabiha Naz, Kiran Chugh, Isha Malik


Background: It is clearly mentioned in the medicine books that blood gas analysis from arterial puncture is the gold standard. But in the past few years it is commonly seen that clinicians have started trusting on venous blood gas analysis as well as started advising VBG (Venous blood gas) in the initial diagnosis of critical patients in emergency setting. Keeping this fact in mind, we designed a study to determine whether VBG could be a better replacement of ABG (Arterial blood gas) in the emergency where diverse pathological conditions are encountered.

Methods: This prospective cross-sectional study comprised of 50 patients of 20-60 yrs age with a variety of diagnoses admitted in the emergency department. 50 paired samples (ABG+VBG) were obtained from them under strict aseptic precautions after obtaining their verbal consent. With a minimum delay of less than 2 min blood gas analysis was performed on blood gas analyzer. Parameters (pH, PCO2, PO2, HCO3, Base Excess and O2 saturation) from ABG and VBG were recorded and compared using Student’s Unpaired ‘t’ test.

Results: pH and HCO3 showed statistical significant (p value <0.05) differences between ABG and VBG, while BE showed statistical non-significant (p value >0.05) difference between them. Contrary to this, PCO2, PO2 and O2 saturation from ABG and VBG showed statistical highly significant (p value <0.0001) differences.

Conclusions: VBG should not be interchangeably considered in place of ABG with regard to pH, HCO3, PCO2, PO2 and O2 saturation in conditions where actual oxygenation status of patient is required (e.g.; hypovolemic shock, respiratory disorders, mechanically ventilated patients, etc.)


Arterial blood gases, Diabetic ketoacidosis, Hypovolemic shock, Venous blood gas

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