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

  1. 0
    I just had a question about a client that i had in clinical the other day.

    She is 87, and was admitted with hypoxia and pneumonia. Her BNP on day one was 0, on day 2 was 398 and on day 3 was 727. CHF was ruled out and her BP was only 100/60 on average, but she had bounding pulses. Her troponin I also went from 0 to .4 in 24 hours.

    Her history also includes hypothyroidism, mild mitral regurgitation that causes stable a-fib. While at the hospital that afib was less stable as her heart rate was over 100. At one point she had a tachycardic episode related to a bad reaction to the duo-neb treatments which caused her Hr to increase to 150-170. The duo nebs had been initiated on the first day of her admission.
    The doctors weren't concerned with the cardiac values and were just monitoring the situation and focusing on treating the pneumonia with antibiotics.

    Im just trying to figure out then What caused the high bnp and increase of troponin...and what does this value then tell us about this clients heart?

    Based on the fact that CHF was ruled out and the troponin was too low for a MI, my theory is that the troponin could have be caused by ischemia related to hypoxia, related to pneumonia and perhaps the high BNP could have been caused by the fluid bolus that the client recieved in the ED....Which leads me to my final question...can a client have a BP of 100/60 and have fluid volume overload?

    Thanks,
    Sarah
  2. 11 Comments so far...

  3. 2
    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/
    Last edit by hypocaffeinemia on Mar 13, '09
    Sehille4774 and canoehead like this.
  4. 3
    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.
    Sehille4774, MissERN, and canoehead like this.
  5. 1
    elevated bnp's can also be caused by pulmonary htn, which can be seen in pt's with her hx and diagnosis
    nursej22 likes this.
  6. 0
    Quote from ERjodiRN
    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.
  7. 0
    Quote from GilaRN
    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.
  8. 0
    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!
  9. 0
    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.
    Last edit by nursej22 on Mar 13, '09 : Reason: Not finished
  10. 2
    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?
    Last edit by Over-the-hill-Nurse on Mar 13, '09 : Reason: corrected spelling
    Virgo_RN and nursej22 like this.
  11. 0
    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


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