But for the grace of God…

I often get a call from a nurse saying something to the effect of, “Dr. Smith is ready to discharge this patient home as long as he is cleared by nephrology.”

I will tell you, that the pre-test probability that I will “clear” the patient for discharge is high. I want patients to go home and I feel that a lot of what we do in the hospital can be achieved as an outpatient. Send the patient home and I’ll see them in clinic. But one needs to be careful.

I didn’t discharge the patient, but received him when he was readmitted. The patient was admitted with bilateral pleural effusions and respiratory distress. Patient was diagnosed with COPD exacerbation and heart failure.

The patient was on furosemide 40 mg daily at home and this bumped to 80 mg IV twice a day on admission.

Nephrology was consulted to assist with diuretics and added some metolazone on day 2. That was a one time order and not repeated. Adding a thiazide, metolazone, to a loop diuretic part to increase diuresis is called sequential nephron blockade. One cause of diuretic resistance, is with chronic loop diuretic use, sodium resorption that occurs after the thick ascending limb can short circuit effective loop blockade. So by stacking diuretics that act distal to the loop increases the effectiveness of the loop diuretic.

The addition of a thiazide or K sparing diuretic to a loop diuretic is an example of sequential nephron blockade.

Robert Centor and I did a podcast about the concept a few years ago. We talked about this seminal article by Dave Ellison.

I would have been a bit nervous adding a thiazide in a patient who already had hyponatremia, but the following day the labs look okay.

The following day is the day of discharge. The morning potassium is replaced with a combination of oral and IV potassium as well as 2 grams of magnesium sulfate.

The nephrologist clears the patient for discharge as long as the potassium is normal. The potassium is almost normal and the patient is sent home. On a combination of furosemide and metolazone!

Three days later the patient collapsed at home and during resuscitation is found to have a cardiac arrhythmia and potassium of 1.6.

Know your diuretics. Respect the diuretics

Also keep in mind this propensity matched trial of metolazone in acute decompensated heart failure. They found a large fraction of the excess mortality found with metolazone could be explained by hypokalemia.