A potassium of 6.8 and the order that saves the heart
Three drugs are on the tray. Only one buys you time, and it doesn't lower potassium at all.
Potassium comes back at 6.8, peaked T-waves on the monitor. What kills this patient?
The heart. Potassium runs cardiac conduction.
How fast are we talking?
Fast. I want a monitor and the crash cart now, not after the paperwork.
You have calcium gluconate, insulin with dextrose, and a binder. Which goes first?
Calcium.
So calcium brings the potassium down?
No. And that's the part people fail. It doesn't lower potassium at all.
Then why give it first?
It stabilizes the heart. Stops it fibrillating while the other drugs do the real work.
So what actually lowers it?
Two different verbs. Insulin shifts it into cells.
Temporary, then.
Temporary but fast. The binder, or dialysis, removes it from the body.
Give me the order as a phrase.
Protect, shift, remove. In that order, every time.
Why does dextrose go with the insulin?
Insulin drives potassium and glucose into cells together. No dextrose, and you cause hypoglycemia.
So the insulin is for the potassium, not the sugar.
Exactly. The sugar just keeps the patient safe.
Now the patient is anuric, end-stage renal. Does the plan change?
The endpoint does. With no kidneys to excrete it, shifting only buys time.
So the definitive move is?
Dialysis. A binder is slow and partial. Dialysis is how you actually clear it.
One-line summary?
Protect the heart first, then shift, then remove. And the drug that saves the heart never touches the number.
↑ answer it in your head first ↑
Traps
- ⚠ Giving calcium and assuming potassium is now lower. Calcium protects the heart; it does not shift or remove potassium.
- ⚠ Reaching for the binder first. It works, but far too slowly to matter in an emergency.
- ⚠ Forgetting that insulin needs dextrose, or you trade hyperkalemia for hypoglycemia.