Bnp

This forum made possible through the generous support of SDN members, donors, and sponsors. Thank you.

rm61

New Member
10+ Year Member
Joined
Feb 10, 2011
Messages
4
Reaction score
0
Med student learning to look at chest xrays. Confused about BNP and heart failure and 'pulmonary congestion'. The other day heart was large bilateral effusions and BNP about 600 and radiologist said no failure. Any simple explanations?

Members don't see this ad.
 
Med student learning to look at chest xrays. Confused about BNP and heart failure and 'pulmonary congestion'. The other day heart was large bilateral effusions and BNP about 600 and radiologist said no failure. Any simple explanations?


That failure is not a radiographic diagnosis.
 
That failure is not a radiographic diagnosis.

That and BNP is kinda a ****ty test and not a good substitute for a physical exam. In patients with chronic failure, you will see BNPs in the thousands and they wont be volume overloaded and sometimes in new failure you will see the BNP in the low hundreds and they will be.

The only time we really use BNP at my hospital is if the patient has concomitant COPD and heart failure and the diagnosis is really unclear from their presentation.
 
Members don't see this ad :)
You wouldnt believe how many bnps are ordered by the ER here before they call me to tell me the patient they want to admit has "CHF", Systolic HF,
should be a clinical diagnosis before a lab diagnosis.
 
BNP of 600, the patient very likely has CHF. Now, whether the patient has a CHF exacerbation is a clinical diagnosis. As pointed out by above posters, you can't make CHF exacerbation diagnosis from either an isolated CXR and/or an isolated BNP. Also, BNP's are ordered far too often. Anything that stretches the atria can lead to an elevated BNP. You could have a patient with bad cirrhosis or bad renal failure/end stage renal with serious volume overload/edema issues and they can get an elevated BNP. Sometimes the BNP won't even be that high even in patients with a a CHF exacerbation (haven't seen it that many times, but it can happen). Obesity, for one thing, can falsely depress the BNP level.

Just because a radiologist says there is no CHF doesn't mean there is no CHF, either. Chest radiographs can be misread, or a patient can be in right sided CHF but NOT left sided CHF (and thus not have appreciable pulmonary edema on CXR). CHF exacerbation is a clinical diagnosis, and one that is often missed (or misapplied/given when it should not be).
 
I generally don't care what the BNP is, so long as its elevated. If its 300ish, they are sob, they have LE edema and bibasilar rales on physical exam, I call it CHF. Doesn't matter if the bnp is 300 or 3000. If they have no edema and no rales I rarely will venture out and call it a chf exacerbation, irrespective of any lab/xray.
 
i agree with the above when saying that clinical indicators trump anything else. BNP is useful for questionable cases (sometimes), but only for it' negative predictive value. A BNP below 100 and you can be pretty sure it's not heart failure. Of course, renal patients, liver cirrhotics may have elevated BNPs.
The only other evidence-based use of BNP is in heart failure patients admitted to the hospital for CHF exacerbation, it is recommended not to discharge those patients with a BNP above 500 ( trend during stay), as they are more likely for re-admission in the near future. This is a bit ridiculous in a number of scenarios, but i have thought about it for some cases.
That's about it, but I'm sure there are some good studies going on right now on the subject of bnp in heart failure addressing confounding factors and so on.
Lastly, to say someone does not have heart failure with b/l pleural effusions and bnp of 600, and no other information is silly, I'm sure there is more to that conclusion then just xr and bnp.
 
Last edited:
Top