Anyone getting VQ scans any more?

[Angry Birds]

Working in the community setting, I often will not be able to get a CTA on someone with renal impairment based on their labs. The radiologist will flat out refuse and with that the tech.

So, I end up shipping these patients to a tertiary care center. I suspect though that at the mothership they just end up getting CTA's anyways. Is this assessment correct? Or do they end up getting VQ's?

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[bravotwozero]

Wow I've never had radiologists refuse to do vq scans at my community shop. Y'all need to hire some new radiologists


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[VeitVat]

I think the op said the radiologist refused CTA, which he is right to do if the patient is at high risk for renal insult.

This is so because VQ scans do remain available and remain commonly performed. When an alternative test that will spare the patient at risk for kidney injury is available it should be done.

 

[bravotwozero]

Whoops, don't think I should respond to posts in a caffeine deficient state. Yeah I totally read that wrong.

At my shop I got right to vq if I can't do a CTA. If I couldn't do a VQ, that might create some interesting problems, and I'd likely push for a transfer for a VQ.

Something to consider - can we rule out PEs with a non contrast chest MRI?


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[DO2016EM]

We go straight to V/Q if there is renal impairment.

 

[gutonc]

I think the op said the radiologist refused CTA, which he is right to do if the patient is at high risk for renal insult.

This is so because VQ scans do remain available and remain commonly performed. When an alternative test that will spare the patient at risk for kidney injury is available it should be done.

I'm in a large metropolitan area with 12 hospitals in 5 different hospital systems. 2 of the 12 hospitals have the ability to do V/Q scans (I learned this one unfortunate weekend on call covering 8 of those 12 hospitals where I had to figure out where to transfer the dude so he could get a V/Q scan).

If your suspicion is high enough in this scenario, why not just start a NOAC +/- admit? Bonus points for a d-dimer and Doppler beforehand...either positive or negative.

 

[Old_Mil]

Working in the community setting, I often will not be able to get a CTA on someone with renal impairment based on their labs. The radiologist will flat out refuse and with that the tech.

So, I end up shipping these patients to a tertiary care center. I suspect though that at the mothership they just end up getting CTA's anyways. Is this assessment correct? Or do they end up getting VQ's?

Hardly anyone gets a V/Q scan anymore, primarily because if it isn't clearly read as negative it has no diagnostic value...and with CTAs being 'standard of care' radiologists are worried about the malpractice risk that comes with reading V/Q scans as negative.

 

[deleted547339]

I get them sometimes on the inpatient side. If unable to get one, I'll go BLE duplex + heparin drip.

 

[GeneralVeers]

I can't believe we still have to fight over the mythical "contrast-induced nephropathy" which probably isn't common at all if it even exists.

That being said, rather than have the fight, I just admit the patient for non-urgent VQ in the morning.

 

[DrBowtie]

Hardly anyone gets a V/Q scan anymore, primarily because if it isn't clearly read as negative it has no diagnostic value...and with CTAs being 'standard of care' radiologists are worried about the malpractice risk that comes with reading V/Q scans as negative.

Odds of a definitive V/Q read increase greatly if the CXR is clear.

 

[Groove]

Annals had a great study on the fallacy of contrast induced nephropathy a few months ago that I recommend reading. It was a massive retrospective cohort of like 18K patients. It was most interesting.

Conclusion
In the largest well-controlled study of acute kidney injury following contrast administration in the ED to date, intravenous contrast was not associated with an increased frequency of acute kidney injury.

In spite of the evidence against contrast induced nephropathy, it can be difficult at times to change your practice when you have so many older consultants and other docs who are still out of touch. Also, the regional standard of care is not always evidence based. It's no different than giving bicarb for a low pH. That being said, if you use contrast, know that you have more than a leg to stand on as far as evidence based practice. Some of the pt's in that study had a Cr up to 3.9 and eGFR of 15 and they still squirted them! Yipes.

Personally, if I have a pt with AKI (mild) needing a PE rule out, I use shared decision making with the pt and educate them on the risks and benefits of contrast. I try to be objective about it. Honestly, most opt for VQ and want to avoid the contrast. Pt's get spooked easily. My rad techs will call me if I order a CTA on a GFR < 30 and ask if I really want to squirt. I can override their protocols if the pt consents. On occasion with some of the pt's with AKI that opt for contrast, I have been known to bolus them a liter and dose them with NAC before the CTA. (voodoo) Most of the time we end up doing a VQ for these pts and let's be honest, it's not a horrible test. NPV is great, and PPV is pretty good when pre-test probability is moderate to high. Luckily, my radiologists have no problem giving me negative VQs. (shocking)

 

[namethatsmell]

Count me in the pro VQ group. I probably get them a couple times a month and the rads guys give a legitimate read with it. As said above it's a good test if the cxr is clear and you don't have somebody waffling behind a hedge when they're reading it.


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[deleted109597]

As said above it's a good test if the cxr is clear and you don't have somebody waffling behind a hedge when they're reading it.

So, who is reading yours if not radiologists? Because that's who you're describing.

As above, the data shows that today's contrast isn't yesteryears contrast. We aren't fubaring people's kidneys anymore. However, not everyone buys into this, and you're stuck.
A dose of lovenox and whatever your hospital's policy is the right answer in the moment, and fixing your hospital's policy is the right answer for the long run. Or, leaving the hospital and after doing so writing a scathing report about how they refuse to update to standards can also work. But that's called burning bridges.

 

[n2b8me]

admit the patient for non-urgent VQ in the morning

 

[namethatsmell]

So, who is reading yours if not radiologists? Because that's who you're describing.

As above, the data shows that today's contrast isn't yesteryears contrast. We aren't fubaring people's kidneys anymore. However, not everyone buys into this, and you're stuck.
A dose of lovenox and whatever your hospital's policy is the right answer in the moment, and fixing your hospital's policy is the right answer for the long run. Or, leaving the hospital and after doing so writing a scathing report about how they refuse to update to standards can also work. But that's called burning bridges.

Mine are willing to say "no evidence of PE". If my ptp isn't sky high I accept it per practice at this hospital. If it's "less than 5%" I engage in shared decision making. If it's higher than that it's usually lovenox or noac.


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[GeneralVeers]

admit the patient for non-urgent VQ in the morning

Exactly. I don't spend too much mental energy fighting with CT techs, negotiating with the patient, giving NAC or any other nonsense. The easiest thing for me is to just admit them and move on to the next patient. Bear in mind I work nights, so getting a VQ after 5PM is an impossibilitiy.

 

[Petypet]

What to do for cases where its emergent? V/Q takes at least half a day, more if the patient comes in after 6 pm. Such as in the wells high risk population.

 

[flasheroonie]

As long as their original CXR is normal and you have a contraindication to giving the patient contrast, a V/Q scan can and should be a good option to r/o PE.

Always remember that you should always consider pretest probability. If it's high, you might as well treat and sort it out later. Better to have a living patient and a bad diagnosis than a dead patient and a perfect diagnosis.

 

[GeneralVeers]

What to do for cases where its emergent? V/Q takes at least half a day, more if the patient comes in after 6 pm. Such as in the wells high risk population.

The patient will obviously get admitted. If high concern for PE then start on Lovenox or Heparin. If emergent, then you could make the case for doing the CTA in the presence of contraindications.

 

[deleted547339]

Annals had a great study on the fallacy of contrast induced nephropathy a few months ago that I recommend reading. It was a massive retrospective cohort of like 18K patients. It was most interesting.

Conclusion
In the largest well-controlled study of acute kidney injury following contrast administration in the ED to date, intravenous contrast was not associated with an increased frequency of acute kidney injury.

In spite of the evidence against contrast induced nephropathy, it can be difficult at times to change your practice when you have so many older consultants and other docs who are still out of touch. Also, the regional standard of care is not always evidence based. It's no different than giving bicarb for a low pH. That being said, if you use contrast, know that you have more than a leg to stand on as far as evidence based practice. Some of the pt's in that study had a Cr up to 3.9 and eGFR of 15 and they still squirted them! Yipes.

Personally, if I have a pt with AKI (mild) needing a PE rule out, I use shared decision making with the pt and educate them on the risks and benefits of contrast. I try to be objective about it. Honestly, most opt for VQ and want to avoid the contrast. Pt's get spooked easily. My rad techs will call me if I order a CTA on a GFR < 30 and ask if I really want to squirt. I can override their protocols if the pt consents. On occasion with some of the pt's with AKI that opt for contrast, I have been known to bolus them a liter and dose them with NAC before the CTA. (voodoo) Most of the time we end up doing a VQ for these pts and let's be honest, it's not a horrible test. NPV is great, and PPV is pretty good when pre-test probability is moderate to high. Luckily, my radiologists have no problem giving me negative VQs. (shocking)

I wouldn't go so far as to say CIN is a fallacy. It may be a fallacy and it's certainly debated/debatable, but it's hard to say it's definitively not true....

 

[deleted109597]

I wouldn't go so far as to say CIN is a fallacy. It may be a fallacy and it's certainly debated/debatable, but it's hard to say it's definitively not true....

The data for today's contrast is pretty robust that it isn't harmful.
The noise in the signal is the old crap.

 

[namethatsmell]

The data for today's contrast is pretty robust that it isn't harmful.
The noise in the signal is the old crap.

Have you been able to change the practice at your shop? What are the Cr or GFR cutoffs for contrast where you work?


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[deleted109597]

At my shop where I make the rules (FSED) I don't have a cutoff.
If there is concern for AKI, we address that before any contrast given.
At the other hospital?
That's funny. Even showing the evidence to the radiologists is met with "oh well, we aren't doing it because reasons."

 

[deleted547339]

The data for today's contrast is pretty robust that it isn't harmful.
The noise in the signal is the old crap.

I'd say that it's fair evidence, but I tend to believe it exists. My understanding is that the evidence pro-CIN is more robust in the cardiac cath literature, but I'm not super firmiliar with it.

 

[Groove]

I wouldn't go so far as to say CIN is a fallacy. It may be a fallacy and it's certainly debated/debatable, but it's hard to say it's definitively not true....

The fallacy would be to believe that it is prevalent among pt's with modern contrast mediums. Sure, the old high-osmolar contrast mediums (and some LOCM) were nephrotoxic but we've had multiple studies in the past 10 years showing no evidence of impaired renal function causatively linked to modern contrast medium. These findings have been validated repeatedly. However, old habits die hard and we still keep pounding these beliefs into everyone's head. Is it a real entity? Yes. Is it prevalent among modern contrast mediums? No.

The data basically shows that the prevalence of Cr increase among pt's you admit to the hospital with no renal impairment and no exposure to contrast medium is identical to the pt's you admit who've just had an IV contrast load. Yet, everyone keeps pointing to the contrast and going "it was the dye!". The old studies predominantly used uncontrolled populations with the supposition that Cr never changed in the absence of IV contrast which is completely false.

Now, can you practice with the predisposed supposition that CIN is much more prevalent than recognized and avoid dye in all AKI? Sure you can. I'm just saying that belief would not be supported with the majority of newer evidence based literature we have out there now.

Here's a good read. One of many.

Do CT scans cause contrast nephropathy?

There is no evidence that safer contrast dyes cause creatinine elevation. The highest quality propensity-matched study of CT scans performed at the Mayo Clinic found no effect of contrast dye on renal function.

 

[deleted109597]

Maybe we can talk about iodine allergies next.
Or shellfish.
Or just contrast in general.

 

[DrBowtie]

Maybe we can talk about iodine allergies next.
Or shellfish.
Or just contrast in general.

CIN exists from a medicolegal prospective until the nephrologists say it doesn't.

Shellfish Allergy is not a contraindication.

Check out ACR contrast manual for all you want to know and more about contrast. It was recently updated in May.

 

[Rendar5]

CIN exists from a medicolegal prospective until the nephrologists say it doesn't.

Shellfish Allergy is not a contraindication.

Check out ACR contrast manual for all you want to know and more about contrast. It was recently updated in May.

Not a fight worth having with radiology. If it's that emergent I get the scan before the creatinine comes back, that way there is no issues at all with my radiology department. If not, I get a VQ scan which is relatively easy to get here. If I'm at a place where it's not, just admit.

 

[deleted109597]

CIN exists from a medicolegal prospective until the nephrologists say it doesn't.

Nephrologists say to give kayexalate, and there's been successful lawsuits for giving it due to colon necrosis. So no, you don't have to do what they say when what they say is wrong.

Shellfish Allergy is not a contraindication.

No **** sherlock. That was the point I was making.

Check out ACR contrast manual for all you want to know and more about contrast. It was recently updated in May.

A link for those that can't find it. Manual on Contrast Media v10.3 - American College of Radiology

 

[DrBowtie]

Nephrologists say to give kayexalate, and there's been successful lawsuits for giving it due to colon necrosis. So no, you don't have to do what they say when what they say is wrong.

While the paper from your literature is interesting, EM is at best the third biggest stakeholder in this process. Until the other two (Radiology and Nephrology) are on board, you won't see any changes. Nothing more damning than reading a note with AKI 2/2 CIN. Same issues with NSF which has all but gone away with newer agents.

The guys who spend 2-3 years additional years focusing exclusively on renal pathophysiology will always be the most credible sources in the witness box on this issue whether right or wrong.

 

[deleted109597]

While the paper from your literature is interesting, EM is at best the third biggest stakeholder in this process. Until the other two (Radiology and Nephrology) are on board, you won't see any changes. Nothing more damning than reading a note with AKI 2/2 CIN. Same issues with NSF which has all but gone away with newer agents.

The guys who spend 2-3 years additional years focusing exclusively on renal pathophysiology will always be the most credible sources in the witness box on this issue whether right or wrong.

Except that there is data that belies their plural anecdotes.
And from the ACR manual you referenced but clearly didn't read very well:

At the current time, it is the position of ACR Committee on Drugs and Contrast Media that CIN is a real, albeit rare, entity. Published studies on CIN have been heavily contaminated by bias and conflation. Future investigations building on recent methodological advancements [3,4,7,9], are necessary to clarify the incidence and significance of this disease.
...
The overall incidence of PC-AKI in studies of cardiac angiography is higher than it is in studies of patients who receive IV iodinated contrast medium. Therefore, data from cardiac angiography studies likely over-estimate the risk of CIN for patients undergoing IV contrast-enhanced studies [2,6].

Of course, it's a useless fight with the weasels on the fence with the hedge, but plenty of data says they don't necessarily need IV contrast with the new generation scanners. So they're arguing both sides wrongly. If you don't give it to "save the kidneys" per them, you're screwed with a "suboptimal read", but if you give it so they'll read it right, they'll mention "contrast given even though discussion with physician had concern for CIN."
Sigh.

 

[DrBowtie]

Except that there is data that belies their plural anecdotes.
And from the ACR manual you referenced but clearly didn't read very well:

Of course, it's a useless fight with the weasels on the fence with the hedge, but plenty of data says they don't necessarily need IV contrast with the new generation scanners. So they're arguing both sides wrongly. If you don't give it to "save the kidneys" per them, you're screwed with a "suboptimal read", but if you give it so they'll read it right, they'll mention "contrast given even though discussion with physician had concern for CIN."
Sigh.

Not sure how my statements are discordant with the ACR statements? Real but rare seems about right.

Thanks for unloading your frustrations on someone willing to engage in a dialogue. Makes me really want to continue.

 

[deleted109597]

Real but rare, and then followed by IV contrast risk is over estimated. So over-estimation of rare.
How rare is that? Super rare?

Your argument is that we should listen to the nephrologists even though we know they're wrong, because we are likely to get sued because of it. I'm just saying that's intellectually lazy. I mean, hey, practice however you want, I just don't want you to lead other people down that path.

 

[deleted480308]

While being pimped on PEs last year, I got laughed at by the residents on the IM floor when mentioning v/q as an option because "no one does that anymore". Clearly some regional stuff going on there because clearly someone does v/q scans

 

[DrBowtie]

Real but rare, and then followed by IV contrast risk is over estimated. So over-estimation of rare.
How rare is that? Super rare?

Your argument is that we should listen to the nephrologists even though we know they're wrong, because we are likely to get sued because of it. I'm just saying that's intellectually lazy. I mean, hey, practice however you want, I just don't want you to lead other people down that path.

The unstated difference is between arterial administration in cardiac cath and volumes used in that vs. venous administration in CT and volumes used in that. You aren't comparing apples to apples so I'm not surprised there are differences.

You can do what you want, especially in your FSED. If you do have a "real but rare" case, you'll have plenty of expert witnesses in line to cash checks.

Back to the original comment on V/Q and definitive reads, ask your radiologist about using the Trinary interpretation model rather than probabilistic interpretation model.

 

[Angry Birds]

While being pimped on PEs last year, I got laughed at by the residents on the IM floor when mentioning v/q as an option because "no one does that anymore". Clearly some regional stuff going on there because clearly someone does v/q scans

Yes, and this thread itself is evidence of the great variation in practice. When I was in residency, my attending told me, "Get consent from the patient after explaining the risk of CIN and then proceed with the study." I tried to do this in the community setting and I got talked down to by the radiology attending like I was a kindergartner who didn't know what I was doing. I argued back about "the myth of CIN" but I couldn't pull up the article off hand.

But in any case, look at the disagreement in this thread amongst ER doctors. Sigh.

 

[GeneralVeers]

Yes, and this thread itself is evidence of the great variation in practice. When I was in residency, my attending told me, "Get consent from the patient after explaining the risk of CIN and then proceed with the study." I tried to do this in the community setting and I got talked down to by the radiology attending like I was a kindergartner who didn't know what I was doing. I argued back about "the myth of CIN" but I couldn't pull up the article off hand.

But in any case, look at the disagreement in this thread amongst ER doctors. Sigh.

Should be no disagreement, it's not like this is global warming.......one side is clearly wrong in this discussion based on facts.

 

[deleted109597]

You can do what you want, especially in your FSED. If you do have a "real but rare" case, you'll have plenty of expert witnesses in line to cash checks.

This is literally true in every possible medical malpractice case. I'd rather practice on the best evidence possible.

The unstated difference is between arterial administration in cardiac cath and volumes used in that vs. venous administration in CT and volumes used in that. You aren't comparing apples to apples so I'm not surprised there are differences.

It's not unstated. It's literally the line before the line I quoted.

In the last two decades, the CIN literature has been dominated by reports of patients who have undergone cardiac angiography with iodinated contrast medium. Cardiac angiography differs from IV contrast medium administration in three major ways: 1) the injection is intra-arterial and supra-renal, 2) the injection requires a catheter that can dislodge atheroemboli, and 3) the contrast medium dose to the kidneys will be more abrupt and concentrated [2,6,51,52].

I'm not the one comparing apples to oranges, it's you. You're conflating the risk of CIN from angiograms to IV contrast, which the ACR explicitely says is overstated due to the poor studies. They say it is real but rare, but from angiograms, not from Contrast-enhanced CTs.

 

[Apollyon]

Should be no disagreement, it's not like this is global warming.......one side is clearly wrong in this discussion based on facts.

Yeah, but I'm still not clear, between a quite reasonable radiologist, and Dr. McNinja being 100% snarky. The snark does not read well.

 

[deleted547339]

This is literally true in every possible medical malpractice case. I'd rather practice on the best evidence possible.


It's not unstated. It's literally the line before the line I quoted.

I'm not the one comparing apples to oranges, it's you. You're conflating the risk of CIN from angiograms to IV contrast, which the ACR explicitely says is overstated due to the poor studies. They say it is real but rare, but from angiograms, not from Contrast-enhanced CTs.

You're getting salty in your old age. Lol

 

[Angry Birds]

Should be no disagreement, it's not like this is global warming.......one side is clearly wrong in this discussion based on facts.

lol you provoke on purpose right?
You an Alex Jones fan?

 

[e30ftw]

VQ scan is like the deepest darkest cavern of the PE work up rabbit hole.

Once you've gone that far, you're ready to admit defeat in discharging the patient who probably never should have had a D dimer ordered in the first place and just give lovenox and admit for the VQ...

I am skeptical of CIN but SOC in my area is avoiding contrasted CTs in pts w Cr > 1.6 and if I am unable to r/o PE in a pt who is > low risk for I will anticoagulate them and get a VQ.

 

[DrBowtie]

This is literally true in every possible medical malpractice case. I'd rather practice on the best evidence possible.


It's not unstated. It's literally the line before the line I quoted.

I'm not the one comparing apples to oranges, it's you. You're conflating the risk of CIN from angiograms to IV contrast, which the ACR explicitely says is overstated due to the poor studies. They say it is real but rare, but from angiograms, not from Contrast-enhanced CTs.

As I said, do what you want. Until further data comes out, you're going to have a tough time changing entrenched policies.

 

[Angry Birds]

Oh I should mention that the hospital I was working at did not have VQ scans so this ends up being a transfer. It would be quite easy if I could just admit.

 

[deleted109597]

As I said, do what you want. Until further data comes out, you're going to have a tough time changing entrenched policies.

What further data?
This is 18000 patients http://www.annemergmed.com/article/S0196-0644(16)31388-9/fulltext.
If that's not enough, this one is 107,000 patients. http://www.annemergmed.com/article/S0196-0644(17)30881-8/fulltext.

Is this one of those "it's not externally valid unless it's done at my hospital" or "It's not in a radiology journal so it doesn't count" or what?
What more evidence do you need?

 

[DrBowtie]

What further data?
This is 18000 patients http://www.annemergmed.com/article/S0196-0644(16)31388-9/fulltext.
If that's not enough, this one is 107,000 patients. http://www.annemergmed.com/article/S0196-0644(17)30881-8/fulltext.

Is this one of those "it's not externally valid unless it's done at my hospital" or "It's not in a radiology journal so it doesn't count" or what?
What more evidence do you need?

As I said, the data is emerging but as the third stakeholder, your literature won't be the predominant driver in institutional policy change. Might sting to hear but that's the reality.

Btw, the second article was behind the paywall for me.

 

[DrYoda]

Our radiologists refuse if the patient's GFR is under a certain arbitrary number. If it's a patient that's old enough/has risk factors requiring admission I just admit and tell the admitting doc they need a V/Q scan. I think I've ordered one out of the department in the past year and it was a slightly tachy, on oral contraception 20-something year old with no hx of pulmonary pathology and an elevated ddimer who I thought it would be a crime to admit.

 

[DrBowtie]

BTW, here is the basis behind what is a pretty common policy across 10+ sites I've worked at which is restriction of contrast below GFR of 30:

"Four large studies released in 2013 and 2014 (each with >10,000 patients) have addressed selection bias in the unenhanced CT population through use of propensity score adjustment and propensity score matching [3,4,7,9]. Although the conclusions from these studies differ somewhat, all four have shown that CIN is much less common than previously believed. In patients with a stable baseline eGFR ≥45 mL / min/1.73m2 , IV iodinated contrast media are not an independent nephrotoxic risk factor [3,4,7,9], and in patients with a stable baseline eGFR 30-44 mL / min/1.73m2 , IV iodinated contrast media are either not nephrotoxic or rarely so [3,4,7,9].

Despite this common ground, there are differences among these studies [3,4,7,9] in the covariates chosen for inclusion, the method of controlling baseline renal function instability, the definitions of AKI, and the nuances of the statistical methodology. These differences likely explain the different conclusions drawn between these studies for patients with Stage IV and Stage V chronic kidney disease (eGFR <30 mL / min/1.73m2 ). In particular, two propensity-score matched studies [3,4] have shown that IV iodinated contrast material is an independent nephrotoxic risk factor in patients with Stage IV and Stage V chronic kidney disease, while two others were unable to find such evidence." - ACR Contrast Manual.

So until this is clarified with further data, the policies will remain. By looking at the first study posted by Dr. McNinja, the study population isn't as relevant to the issue at hand as ranges of GFR in all arms were largely above the CKD 4 and 5 cutoff and not powered for those below the 30 GFR level. Much of the conclusion is that it is safe to give contrast above 30 GFR which should be in line with most Radiology department policies.(Edited because reading small print on the phone is tough)

 

[deuist]

I wouldn't go so far as to say CIN is a fallacy.

I will, as do the radiologists.

 

[Nephro critical care]

Our hospital ( a nationally regarded hospital ) dosent believe in CIN from IV dye. They will give contrast to mid 3s. They think intraarterial contrast can cause CIN but not IV dye. They also refuse to read any VQ scan as other than indeterminate. So I just stopped getting them. I also won't request them to try to make do with a little less dye as they will read it as inadequate bolus , unable to rule out peripheral PEs. So I just get the regular CT if I have high suspicion with a liter bolus of saline.