Thursday, December 11, 2014

Saith the A-line of the Swan: "There but for the grace of God go I"

I never never never, well, hardly ever use arterial lines (A-lines) anymore.  I just don't need them.  The nurses want them, but I mostly refuse, except in in extremis patients with labile pressures on high dose vasopressors.  (I also rarely "float" that Big Yellow Bird the Swan Ganz catheter.  It simply is rare that it provides information that is useful to me.)  Here are some reasons:
  • A-lines increase the volume of blood drawn (and wasted) for laboratory testing, much of which is gratuitous at best, useless or harmful at worst
  • They further limit already limited patient mobility - of an arm no less - and they are an impediment to getting patients out of bed
  • They fail quite often.  I have yet to determine if this is nursing and RT related or the companies are using different construction that reduces catheter integrity - if you have an opinion on this please comment below
  • They are one more invasive device on the list of potential sources of fever - the narrower this differential is, the better
  • They are not obviously more useful than a non-invasive blood pressure cuff
  • They have all the obvious attendant complications of an invasive device.
So I was happy to see the commentary piece in the November 2014 issue of Chest by Allan Garland calling for RCTs of A-lines (a less measured person may have invoked a moratorium on them).  His piece focuses on the lack of data for them, but gives a nod to the notion of "blind acceptance" of established practices, and status quo bias.  Most critical care physicians trained in largish academic centers where their use is commonplace, whether because of tradition, the desire of senior house officers to teach junior ones (hey, you gotta get your numbers up in your procedure booklet somehow), remuneration for procedures in private practice, or other biases.

If you have not already, for the next few months, try to resist the pleas and sirens beseeching you to place an A-line so that you can experience the alternative reality of an A-line free ICU - if you do, and you pay careful attention, I bet you too will find that they are unnecessary and that the threshold for inserting them should be high and the threshold for removing them should be low.

(John Bradford uttered something like "There but for the Grace of God go I" as he watched a criminal being led to execution - in recognition that the potential for human sin lies in all men.)

1 comment:

  1. Although this may be true in many patients, beware of those you are actively killing by over-vasoconstriction. The non-invasive AND radial art line pressures become less reliable and BP drops and as vasopressor dose rises. Femoral art lines are a must. There is literature supporting up to 30% difference in BP. I have had several cases where we were causing over vasoconstriction and MSOF simply by using NIBP or radial. So it isn't only the "in extremis" who need one, and those who do need a femoral art line. Radials only useful for frequent bloods if no central line.

    cheers

    Philippe Rola

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