Lasix Dosage in Acute Decompensated CHF

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, 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:

CHF Lasix 2

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!



2 thoughts on “Lasix Dosage in Acute Decompensated CHF

  1. I am a big fan of some good ol decompensated HF. I have a few thoughts.

    The pump sucks and the enemy is preload. Therefore the treatment focuses on preload reduction hence the Nitro and Lasix. The one and only Corey Slovis drilled in my head as a med student Nitro, Nitro Nitro for HF exacerbation. One interesting fact is Lasix transiently increases vasoconstriction and activates RAA system leading to slight increase in preload initially, hence the importance of Nitro.

    As far as dosing of Lasix, the smartest medicine attending I ever met always harped on doubling the home dose. The DOSE trial from 2011 was supposed to be the definitive trial on which dose; low(home) vs high(2.5xhome). It failed however to show much difference, at least on the surface. The lead author Dr. Felker has some interesting take home points from his study.

    Here are some of his quotes from an interview on emedicine.

    “in DOSE we saw a transient worsening of renal function in the higher-dose arm, but it was quite transient, meaning it was completely gone by day of discharge, and it didn’t seem to have any adverse downstream implications in terms of postdischarge outcomes.” So,” he said, “if you look across the totality of end points, high-dose definitely seems to show a strong signal that it’s preferable to low-dose.”

    “Since a high-dose regimen may relieve dyspnea more quickly without adverse effects on renal function, that regimen is preferable to a low-dose regimen.”

    … clinicians “might be worried about worsening renal function and therefore might not decongest the patient as aggressively, and I think that would be a mistake. The story from DOSE and some observational studies is that aggressive decongestion is a critical part of achieving good outcomes in acute heart failure. It may seem to come at the cost of transient worsening renal function, but that doesn’t seem to be a major problem, as long as it’s monitored carefully.”

    All that being said I am still hesitant to use the high dose, it scares me a little. So I would be inclined to start with the home dose IV and let our friends on the floor determine if more is necessary.

    Here are the links, I referenced.

    • How about the patients whose proper dosing of Lasix is 0mg? Believe it or not these people exist, and you may come across them more frequently than you realize.

      I give you one common and one uncommon example. Conrad did such a great job referencing evidence based medicine in his post, so here i go with some anecdote based medicine. Forgive me.

      1) A 50 year old man comes to your ED with 2h of dyspnea. He takes several blood pressure medications and has questionable compliance. His BP is 245/140, HR 125, RR 32, SpO2 80% RA. He can barely speak more than 1-2 words at a time, his neck veins are not distended, his extremities are not edematous and his lung sounds are diminished with rales heard diffusely. You start him on NIPPV and ask the pharmacist for 2mg IV NTG when your attending pipes in…

      Question: Young doctor, does this man have a volume overload problem or a volume redistribution problem?

      2) An 80 year old man presents to your ED with 1 day of dyspnea. He also reports severe lower abdominal discomfort. EMS started him on CPAP prior to transport b/c his room air pulse ox was found to be 78%. When he arrives to you, his BP is 160/90, HR 125, RR 36, SpO2 97% on 100% FiO2 w/ CPAP 8 cm H20. He speaks in 3-4 word sentences, he has no neck vein distension, with trace pitting edema, his lung exam reveals diminished breath sounds with rales at least 1/2 way up the posterior lung fields. You transition him to BiPAP (10/5, 100%) and notice that his lower abdomen is tense and firm in the suprapubic region with his bladder dome appearing to be near his umbilicus. You US his bladder and find >750ml of urine and an enormous prostate. Nursing places a foley and drains about a liter of clear urine. You are getting ready to order his lasix (you’ve decided on using his home dose IV) when your attending pipes in…

      Question: You sure he needs this lasix partner? Does this man have a volume overload problem, or a volume redistribution problem?

      In summary, remember every pt is different, the 2nd case example is from a case i managed with Irving over the weekend, after relieving his urinary retention the pt had the typical post obstructive diuresis and was on room air within 90 minutes and doing just fine…without lasix (GASP!!).

      Food for thought…carry on.


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