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ABG = A bad gas?
Kelly AM. Can VBG analysis replace ABG analysis in emergency care? Emergency medicine journal : EMJ. 33(2):152-4. 2016. PMID: 25552544
I can’t remember if I have covered the evidence that indicates that for most situations we should be using VBGs and not ABGs in the emergency department in these emails before. This is a nice review of the evidence on the topic. Perhaps the most important thing to remember is the downsides of ABGs: pain, increased technical difficulty, and rare but serious adverse events. The evidence indicates that a VBG as good as an ABG for measuring pH and bicarbonate. For pCO2 the agreement is not great, but Dr Kelly makes the important point that the exact numbers are not as important as the ability to answer a clinical question. If the VBG reveals hypercapnia, the number might not match the ABG, but the patient is clearly going to be hypercapneic.
Also, a VBG with a pCO2 less than 45 mmHg rules out clinically significant hypercapnia with 100% sensitivity (95% CI 97-100%). You shouldn’t need a blood gas to determine the pO2 because you have a sat probe.Bottom line: The VBG should be the go to blood gas for most ED patients.