VBG in a limb and PICCs

Been gone nearly 2 years and back in the ICU. Need a little refresher but hosp. is not a teaching hospital. When doing bloods, I've been 'pushed' into doing VBGs from small, peripheral lines. This makes no sense to me. Even if, as some of my colleagues are stating, we're doing it to follow a trend, we're only trending the perfusion to that arm, no? I don't see the point?

Also, how reliable is a CVP reading from a PICC?

Many thanks for the input!

I am not sure, but I suspect that a venous gas from a peripheral line would not be clinically useful. Are these existing peripheral lines that have been used to give meds/fluids? In our ER, they draw from a PIV but only one time before it is ever used for anything else. I have only drawn venous gases from a central line.

The physicians I currently work with do not order CVPs on PICC lines as it is not considered accurate. It is hard enough to get an accurate read, at times, with a central line. The best ones I have seen are transduced from an internal jugular. IF you were attempting to get a CVP reading from a PICC, you would want to remove any deadspace (i.e. caps).

Only thing a peripheral VBG is good for is checking a lactate, and even then you can just send a lactic acid (gray top on ice for our hospital). ScvO2 is info obtained from blood returning via the vena cava, an SvO2 is a true mixed venous gas drawn off a Swan where you get the mixing of vena cava blood with coronary sinus return. No peripheral VBG is going to get you anywhere near the same info.

CVP off a PICC is worthless too.

If your doc is really concerned about VBG's and CVP's they need to scoot their butt into the room and drop in a central line.

getting a VBG from a Peripheral IV makes no sense to me. Your only getting information from how that limb is utilizing oxygen. At least from a central line is a pretty central location. Although a swan is the most accurate, a central line draw is a close second. seems like poor practise to me.

Thanks for your feedback everyone. It's quite tricky where I work, yes. Docs REGULARLY order VBGs from periph. lines as they say they want to "follow a trend". They also want CVPs from PICCs even if they aren't true CVPs so they can "follow a trend".

Re: Swans, I don't remember the last time I dealt with a Swan...the good old days :-)

There are a number of studies which confirm the accuracy of CVP's from a PICC line,so don't worry about that. Most open-ended catheters are labelled for pressure monitoring. Valved PICCs like Groshongs are not.