Monday, March 28, 2011

Interlude: Referral Politics

Ah, the joy of the referral.

Times have changed. The all powerful target means less time for us, in the ED to reach a diagnosis; often the decision to refer for admission is based on a lack of a diagnosis, coupled with the fact that the hospital says I can't stop and think.

And so, the soft referral. I like to think that most of my referrals are kosher, and if I'm not sure, I'm honest about it. But sometimes, I just don't know what's wrong with a patient, but I'm pretty certain they need longer obs than I can offer in the ED, and maybe more tests. (More tests! The answer to everything!)

I had just a conundrum recently, and was given a hard time by the MedReg. Not necessarily inappropriately; I really couldn't figure out what was afoot, but I tried to be honest about that, and why I though the patient ought to come in.

Her SHO, one of our old trainees, told me a few days later, that she hadn't realised to whom she was speaking, and had been apologetic thereafter. (Apologetic, or worried that I might complain?)

This, of course, if bullshit. If she was rude, and I didn't think she was, especially, then who i am is irrelevant. No mater what some practitioners seem to think, there isn't a sliding scale of how rude you can be to someone, based on their job title.

If, on the other hand, she thought the referral was shit, who I am is equally irrelevant. Shit referrals transcend all boundaries.

Anyway. Last week, I'd seen a young girl, complaining of pleuritic, left sided chest pain, shortness of breath and cough. No temp, pulse 120 bpm, resps 30. Normal bloods, normal chest XR, normal gases. Despite her normal gas, I was still concerned about PE.

(The arterial blood gas measures oxygenation of the blood, and, in pulmonary embolus, should be abnormal.)

The MedReg was distinctly unimpressed, and wanted to know why I hadn't asked for a d-dimer.This is a blood test that, if positive, may indicate the presence of clot. It's more often used to rule the condition out, as it is more commonly negative when there is NO clot, than it is positive when there IS clot.

However, in certain circumstances, where risk is perceived to be high enough, even a negative d-dimer isn't really enough to rule out PE. This is, broadly, Bayesian probability, which deals with pre test probability, and how the result of a given test influences that figure to generate post test probability.

So for example if you have a 15% chance of having a PE, and negative d-dimer would allow me to reduce that below 1%, and I might say that's enough to rule it out. But if the pre test is higher, maybe 50%, then with a negative d-dimer, your post test is only maybe 5 or 6%. Enough to rule out?

I think not.

We backed and forthed on this for a while. Ultimately, it came down to, if she doesn't have a PE, why is she in pain, tachycardic and tachypnoeic. I CAN"T send her home. If she settles in 12 hours - brilliant. If she goes home and dies...

Not so good.

Now, I'm pretty boring, so I'm happy to talk Bayesian probability theory, and the evidence behind d-dimer all night. But it occurs to me that my juniors probably notsomuch, and this was all a bit hard work, for what may have been a soft referral, but was, at the end of it all, a patient with ongoing symptoms, and abnormal vitals.

I've seen cases like this before; not many. One or two, maybe, but that's all you need to know that sometimes what seems unlikely turns out to be real.

And I'm happy for a few uppity fellows to think me a por diagnostician, in exchange for avoiding the coroner's court.


night tech said...

Oooo...wanna debate the use of serial troponins in a STEMI. How about lactic acid determination to rule out septicemia.

There are some merits to actually excercising your clinical skills. Beats the alternative.

night tech said...

Oh...must not forget to repeat that BNP. Just because it was positive last month. Might be clinically relavent.

I love my job!

DrShroom said...

I'd be delighted to have those debates; BNP can kiss my arse; the others: well they have some useful positive predictive value, but as rule outs?
I may have mentioned I'm a bit of a dinosaur... I predate all those tests, so don't place much stock in any of 'em

night tech said...

Afraid it wouldn't be much of an argument...unless you wanted to play devil's advocate. I supect we might be on the same page re use/overuse of lab tests.

I've been at this for a couple of years myself. I get paid a shitload of money to crank out reams of data that few seem capable of interpreting. I suspect much of it is done just to impress.

Someday I might even learn to keep my mouth shut ;)

DrShroom said...

I'm pretty sure we are on the same page, and you're right, it's not the data, it's what you do with it / about it.
I haven't quite learned to keep my trap shut, either. If you figure it out, let me know ;)