Viva la (diuretic) resistance!

This afternoon Dr Feng shared the tale of a middle-aged man who presented with acute on chronic dyspnea felt to be secondary to acute decompensated heart failure. Seems easy, right? Diuresis, diuresis, diuresis… but, what if that’s not enough? What if you come up against…

… diuretic resistance!

diuretic resistance.png

Thanks to our very own, Dr David Ellison (nephrology), we have guidance. If you’ll allow me, I’d like to share some highlights from his 2017 NEJM review article.

How to Recognize Diuretic Resistance In the Labs:

  • Low urine sodium despite maximum recommended dose of diuretic
  • Lack evidence of “contraction” on your chemistry panel (increasing creatinine or bicarbonate)

The 3 D’s of Diuretic Resistance*:

As eloquently explained by Dr Ellison, “A dose of a loop diuretic increases urinary excretion of sodium chloride for several hours, but this is then followed by a period of very low sodium excretion, often termed “post-diuretic sodium retention.” To induce negative sodium chloride balance, the excretion of sodium chloride during 24 hours must exceed its intake. When dietary sodium chloride intake is high, post-diuretic sodium retention will offset the initial natriuresis, especially if the dosing interval is long. In contrast, low intake of sodium chloride permits urinary sodium excretion to exceed intake. The difference in these effects on extracellular fluid volume underscores the importance of dietary intake of sodium chloride, the drug half-life, and the dosing interval, especially in patients with chronic heart failure.”\

In abbreviated terms, when thinking about how to avoid diuretic resistance and improve natriuresis, consider:

  1. Dietary Sodium
  2. Drug half-life
  3. Dosing Interval

*Note: This ridiculous alliteration is all mine, do not hold it against Dr Ellison.

Management of Acute Decompensated Heart Failure

With this background of diuretic resistance in mind, the question remains for how we practically apply this it our patients. You should find the following tips helpful:

  • Initial Diuretic Dose: IV (ggt schedule as below) or bolus (2.5x previous oral dose, BID)
  • Subsequent Doses: increase daily to reach goal UOP
  • Goal UOP: 3-5 liters urine daily until clinical euvolemia is reached
  • Backup Plan: if UOP remains < 3 liters per day, add sequential blockade
  • Sequential Blockade Options: metolazone || HCTZ 50 mg BID || chlorthalidone 50 mg QD
Diuretic Dose.png

Citation: Ellison, D and Felker, G. Diuretic Treatment in Heart Failure Nov 16 2017