OK, time to start pimping some Irish EM research. There’s a fair amount of it and some of it is really useful. I distantly know some of the folk involved but alas have no part in producing any of it!
This is a paper (out of St James’ Hospital, Dublin) that adds to the growing body of info that says ABGs have limited utility. A lot of EDs in Ireland have blood gas analysers in their resus rooms and it’s not uncommon for a venous gas to be drawn when the cannula is places at triage.
- effectively a convenience sample of COPD pts with exacerbations
- got paired ABG and VBG (<5mins between samples)
- a raised CO2 was considered >45mmHg on the VBG
- n = 90 or so
- age 70 or so
- none were intubated
- a third had raised arterial pCO2; 20% were acidotic
- perfect agreement on the question “is the patient hypercarbic?” when a cut off of >45mmHg was used on the VBG
- there were wide variations (average diff between ABG and VBG was 8.6mm) but even with this it still told you what you wanted to know
- pH and bicarb were very tightly correlated
- in other words if the VBG has a high CO2 you need to do an ABG to find out exactly what it is, But if the venous CO2 is <45 then happy days.
- McCanny P, Bennett K, Staunton P, McMahon G. Venous vs arterial blood gases in the assessment of patients presenting with an exacerbation of chronic obstructive pulmonary disease. Am J Emerg Med. 2012Jul.;30(6):896–900. PMID 21908141