It’s *almost* impossible to OD on k. Google it. LD 50 is astronomical. It’s so rare your question is moot.
It’s not a cardiovascular or respiratory depressant. Which is why it’s widely used in surgery.
Worst case scenario is you see weird stuff and 30 minutes later you’re basically sober.
Now, the half life of k is significantly longer than most hallucinogens although it’s not classified as a hallucinogen.
This means you can certainly “stack” your intake and get overwhelmed by it when you least expect it. Still won’t last more than 30-ish minutes. 1 hour max.