Question about Elevated BNP in the absence of CHF..Help Im new to Cardiac!

hypocaffeinemia, BSN, RN · Mar 13, 2009

BNP is excreted renally, so in the context of renal failure/insufficiency it could be elevated as well.

Other than that, BNP is fairly specific to ventricular stretching (call it CHF, call it what you will).

edit to add: Apparently BNP levels can be elevated in the presence of atrial fibrillation without heart failure:

http://www.lowncenter.org/articles/BNP.pdf

http://www.springerlink.com/content/f1288072233u8p16/

GilaRRT · Mar 13, 2009

A BNP of 727 is rather profound. In addition, BNP assessment is a rather sensitive and specific test for the diagnosis of hear failure. However, me must understand the mechanisms behind BNP release to truly understand the implications of elevated BNP.

Remember, BNP is not simply released because of heart failure. It is released in response to ventricular stretching as stated. So, any number of conditions that can elevate the ventricular filling pressure, can potentially cause an elevation of the BNP.

Generally, diabetes, mild renal insufficiency, or even COPD will not cause an elevation of the BNP. Right sided failure and pulmonary embolism can cause mild BNP elevation, so something to consider. However, 727 is rather significant.

Blood pressure is not always a good indicator of ventricular filling pressure. So, her blood pressure may not even be a consideration. Obviously, something pathologic is going on. Did she have an echocardiogram? I would not be surprised to see findings of CHF after the pneumonia clears from her chest x-ray.

ERjodiRN · Mar 13, 2009

elevated bnp's can also be caused by pulmonary htn, which can be seen in pt's with her hx and diagnosis

GilaRRT · Mar 13, 2009

elevated bnp's can also be caused by pulmonary htn, which can be seen in pt's with her hx and diagnosis

True; however, a change from 0-700+ in a few days makes me suspect something acute. Possibly, the other conditions have worked like a physiological "stress test" causing the changes.

ERjodiRN · Mar 13, 2009

True; however, a change from 0-700+ in a few days makes me suspect something acute. Possibly, the other conditions have worked like a physiological "stress test" causing the changes.

of course! it's just that typically with a bnp at that level...if it were true chf, you'd be able to hear her wet breathing without a steth. however, she could very well have congestion without actual failure. regardless, with the trop elev., something in this pt's treatment needs to be changed.

Sehille4774 · Mar 13, 2009

Actually, I went back and looked at the labs...and the bnp was 0 at 14:50, 398 @ 15:01 and 727 at 03:18 the next day. So according to this the BNP went from 0 to 398 in 11 minutes!...Thanks for the insite tho. Im trying to sort out what is important and what is not...I just found it strange that the hospitalist's didnt care much about the state of her cardiac health..in fact the only cardiac med she got was 25mg of lopressor! I also learned from further reading that mitral regurg can casue increased streching of the chambers of the heart due to abnormal blood flow...so that is why now I am really thinking either the lab was wrong or it was a wide open NSS bolus in the ED that did it. Thanks. Im a senior student BTW and my instructor was stumped!

nursej22, MSN, RN · Mar 14, 2009

I am curious how the CHF was ruled out. Was an echocardiogram performed to evaluate ejection fraction? A person can certainly have a big, boggy heart that is only squeezing out 10% and have clear lungs on XR and to auscultation. Then when they get a fluid bolus, uh, oh.

It is my understanding that mitral regurg. can be both a result and a cause of heart failure (stretched LV pulls the valve so it can't close or non-closing valve allows back flow during systole).

I also would suspect right sided HF and pulm. HTN in this pt. How were her neck veins? Any peripheral edema or ascites?

I have never heard of measuring BNP 11 minutes apart. We usually don't do it amy more often than once a day.

Over-the-hill-Nurse · Mar 14, 2009

The purpose of BNP is to help regulate blood volume, the work that the heart must do in pumping blood throughout the body. Both BNP and NT-proBNP are produced mainly in the left ventricle. So when the left ventricle is "stretched" from having to work harder, the BNP concentrations can increase markedly. A person who is given a fluid bolus, such as 500 ml's of saline into the circulation, for example, it affects all the fluid compartments of plasma, extracellular and intracellular compartments (increased blood volume). If that person does not have sufficient oxygenation, myocardial performance and vascular tone, all results in "stretching" of the LV. In simple terms, it is as nursej22 stated, CHF.

But, lung disease such as COPD, or Renal disease, Chronic Hypertension call all cause elevated BNP, but generally you will see this elevated on admit, not suddenly.

CHF makes more sense considering the information you provided. We also do not draw BNP's that closely together. Because of the fluid administration, and the bout of fast heart rate, could have been the cause of the elevation, which may acount for the reasons the hospitalist wasn't concerned. A CXR is not the ideal test to rule out CHF. A echo would have been more conclusive. And hopefully, they ordered another BNP later to help distinguish the cause. I am curious as to what the hospitalist documented what he thought the cause was for the elevated BNP?

Sehille4774 · Mar 14, 2009

All that was documented by the physician was that it was his impression was that this was not CHF and was therefore not planning on any further cardiovascular assessments or interventions at this time.

It was noted that she had a regular cardiologist that was monitoring her MR and ect. on an outpatient basis.

She did not have any renal issues that I am aware of, and BUN and creatinin were fine, with no decreased urinary output. She did have some eletrolyte imbalances such as K, Ca, and sodium, which were slightly low.

I did, however think that she had slight edema (+1 or less) to the legs. This was a very thin woman and it was so slight that it was almost hard to tell.

It seems like the consensus seems to be that she could have CHF..I should check her WBC count which i dont remember off the top of my head. But it seems like it would be easy enough to incorrectly diagnose CHF as pneumonia.

Ccunurse I wish i had just asked that question in the first place about the BNP! this hospital that im at just seems medically backwards in some ways. every week i feel like i see treatment regimens that could use improvement or orders that are way out of wack...but as a pratically new nurse, i lack the judgement to really be able to tell if this Dr's plan off or is it me?....im the student so i has to be me haha!! ill post more lab info on her later today, after i get a nap :)

Virgo_RN, BSN, RN · Mar 14, 2009

Like the others, I'm unaware of how the BNP can be in the 700s without the presence of heart failure. I would expect to see an echo ordered, probably some Lasix given, maybe a cardiology consult and follow up BNP and CXR.

Over-the-hill-Nurse · Mar 15, 2009

Sehelle4774,

Being a student doesn't mean that you lack skills in determining that something "isn't right" about the treatment regime, or when something is going on with your patient. Ask questions by all means. Most physician's don't mind the questions and it is okay to say I don't understand... if it isn't CHF, what was causing her BNP to elevate? Rationale is always important regarding tx modality, and understanding why they are treating the way they are. Being able to understand that, helps you as a nurse take care of your patient more effectively.

Right sided heart failure and left sided heart failure show very different symptoms. Pt's may not exhibit the typical things that you would look at such as "wet" lungs, peripheral edema etc but they can still be in heart failure and not shown on a CXR. Too many times you see dx such as pneumonia and in the end, it was one masking the other. Or a combination of both. Your lady certainly sounds like it could be both. Also curious as to what her EKG looked like? With troponin elevations even as small as 0.4 they could have a non Q-wave MI associated with all the stress on her body from the increased work load. EKG's can tell a huge story regarding the potentially MI, the CHF, Hypoxia, etc..

And be proud of yourself to be able to reconize that something is wrong with "this picture". It is called being a good patient advocate to ask questions and making sure that your patient's are receiving the best care that you can give to them.