How would you manage hemodialysis for an ESKD patient who presents with a phosphorus of 1.6 mg/dl and potassium of 6.5 mEq/L without ECG changes?

Don’t panic.

EKG changes correlate not with plasma K but with intra/extra cell K ratio, that ratio is what determines arrhythmias and muscle weakness, so while agreeing with dialysis with usual bath K (2.0?), check Hb and occult blood stools, review diet and recounsel, is the patient underdualized? ...

I dialyze them slowly, low blood flow, smaller dialyzer, shorter time with 1k bath. I will give them high doses of oral phosphorus (neutrophos 2 packets tid) and repeat potassium a few hours (8 hours) after dialysis and if needed for potassium will dialyze them again.