Monday, August 31, 2015

“The BNP is high – just give Lasix!”

This isn't rocket science, right? If your hypoxic patient has a high BNP and a wet CXR, then you give then a diuretic, and admit them. Done, next patient!

Some POCUS skeptics would argue, however, that using echo in CHF doesn't really affect diagnosis or management.
Of course, many of these same clinicians unironically carry a modern version of the sacred hollow stick around their necks...

Something Doc Cottle always carries: Lit cigarette.
Something Doc Cottle never carries:  Stethoscope.
So, can focused echo help us change our acute management?  

TL;DR - Yes.
TL; Will Read - Yes!

The Case:

An elderly male with a history of systolic & diastolic CHF is brought in by EMS. He describes an acute onset of dyspnea and wheezing 1 hour prior. Worse with lying down and exertion. Denies recent leg swelling or weight gain, and denies fevers, chills, or sputum. 
His systolic BP is > 200 mm Hg. No JVD, but prominent wheezing diffusely.

Before the CXR, ECG, or labs can be obtained, a focused ultrasound is performed.

A flat, collapsing IVC, but…

… numerous B-lines in the bilateral anterior apices, while …

… the EF appears to be only moderately decreased (chronic, per the last echo in the record).

So how does clinical care change based on the ultrasound?

The patient probably doesn’t have volume overload, given the markedly flat IVC. Indeed, he may actually be hyPOvolemic.

The dramatic “hive” of B-lines in the anterior apices, however, suggests that he nonetheless has quite a bit of water in his lungs.***
Plenty of research has shown that the number of B-lines is proportional to increases in pulmonary wedge pressure, to increases in extravascular lung water, and even increases in BNP

So, despite the flat IVC, he most likely has acute decompensated heart failure, due to diastolic heart failure (Scott Weingart has referred to this as SCAPE).

He isn’t volume overloaded, just volume maldistributed!

(*** Yes, a number of other etiologies can produce B-lines/acute interstitial syndrome. But:
  • Bilateral B-lines suggest against pneumonia;
  • Acute development weigh against pulmonary fibrosis or pneumonitis; and 
  • Absence of another severe disease did not support ARDS.)


Since the echo suggests that high systemic vascular resistance is the problem, and not sheer volume overload, he is given 3 nitroglycerin tabs under the tongue (yes, 3 tabs at once).

His wheezing stops almost instantly, like someone had flicked a switch. The pro-BNP eventually came back at a kagillion, but his chest x-ray (obtained long after the nitro was given) looks benign.  This complicates the dialogue with the admitting team.

“Hey, I don’t have to stay the night, do I?”