Cardiorenal is interesting and definitely worth a talk. No to boluerisis et al. The cardiorenal syndrome is part of a constellation of pathophysiologic mechanisms that includes neurohormonal activation, inflammation, etc but elevated central venous pressure and hence renal venous pressure plays a central role. (See Fig.1
http://content.onlinejacc.org/article.aspx?articleID=1224877). Despite what everyone tells you it is not poor perfusion due to "poor forward flow" or "falling off the Starling curve." It's poor perfusion across the kidney because but you've lost the typically high gradient from the arterial pressure and low venous pressure when someone comes in with very high central venous pressure and potential arterial underfilling in the setting of elevated SVR/neurormonal stress, etc.. If you don't buy that see Figure 1 here and teach it to each other.
http://content.onlinejacc.org/article.aspx?articleid=1139427. If the patient truly has symptoms related to elevated filling pressures and is not preload dependent (severe pulm HTN, massive PE, tamponade) diuresis alone is the answer or, even better, ultrafiltration which for reasons unrelated to its superiority has not caught on in most hospitals.
http://circheartfailure.ahajournals.org/content/2/5/499.extract
Yes, some people have massive necks and difficult physical exams but if it smells like heart failure and they have worsened renal failure there is no fault in attempting diuresis. If they have 10 days of massive diarrhea and skin tenting with a history of cardiomyopathy, yes, they can be dehydrated and fluid is the answer. Use your judgement and G-dspeed to you.
Hint: If you can't tell volume from their JVP easily and they get an echo look at their IVC or better yet look yourself if you have a hand-carried device. You can tell the CVP from that. In broad strokes >2.5 cm IVC diameter is consistent with elevated CVP and <1.5 cm is likely pretty low CVP. If it's between but collapsing at least 50% with inspiration the CVP is pretty normal. They could still have elevated left-sided filling pressures but probably not massively in the subacute phase that leads to heart failure inpatient stays. Acute MI is another story. Go to the echo lab and ask about the IVC. It's one of the last images they acquire but it doesn't often get reported even when they acquire the image.
