Acute decompensated CHF is something we see on almost every shift in the ED. Presuming the patient is not hypotensive, more than likely that patient will be receiving IV Lasix. When I was a resident, I was taught that if the patient is on Lasix at home, find out their home dosage and just give that IV. At SGH, it seems that many residents will find out the home dosage, double it, and give that dosage IV. So, I went on a quest to figure out if there are actually any reasonable, evidence-based recommendations on the subject.
My first stop was EBMedicine.net, which has a large library of evidence-based medicine articles on a variety of topics; you guys have access to all of this material. Having written an article for this publication, I can verify that these articles are well-researched and heavily peer reviewed and edited. So I found an article from 2014 called “Current Guidelines for the Evaluation and Management of Heart Failure”. Here is their recommendation regarding IV Lasix usage in acute decompensated CHF: “If patients are already receiving loop diuretic therapy, the initial IV dose should equal or exceed their chronic oral daily dose and should be given as either intermittent boluses or as a continuous infusion. Urine output and signs and symptoms of congestion should be serially assessed, and the diuretic dose should be adjusted accordingly to relieve symptoms, reduce volume excess, and avoid hypotension.” (ACCF/AHA, Class I, Level B).
There are a couple of interesting things here. First is that the initial IV dose of Lasix should be at least as much as the patient’s DAILY dose, meaning if they are on 40mg BID, we should give 80mg IV. The other interesting thing is that they do not really specify if we should be giving more than this or not. The editor made this comment regarding dosage: “The ESC guideline does not specify dosing, noting the lack of good evidence for the use of high-dose over low-dose loop diuretics and tradeoffs that include transiently worsened renal function.”
Ok, so there’s no firm recommendation over what dosage should be used, other than it should be at least as much as the daily home dosage. So then I went to the AHA’s website and found a great article that addressed this exact question. This is what they had to say: “In a retrospective analysis, Butler et al22 identified higher loop diuretic dosage as an independent predictor of worsening renal function in ADHF even after controlling for disease severity and the degree of diuresis…however, it may be impossible to completely adjust for other confounders of disease severity that could effect both diuretics requirements and the risk of worsening renal function. Thus, it remains unknown whether higher diuretic requirement are simply a marker for higher risk or whether higher doses of loop diuretics contribute directly to the development of the cardio-renal syndrome in patients with ADHF.”
Then they give this graph, essentially stating that the more Lasix someone is given, the higher the mortality. Of course, the confounding factor here is that sicker people are probably given more Lasix, but here it is:
So, unfortunately, I think that all we can reliably conclude is to verify the patient’s home dosage, and give the total daily home dosage, or more, IV. I think what I will do is find out their daily home dosage, give that, then reassess the patient and give more if necessary. But it’s not wrong to find out their daily dosage and double it, so you will need to develop your own practice habits and talk to other attendings about this and get their opinions. I welcome and encourage any comments!