My Brother Has. High Potassium Level 9 Days Post- Op

My brother has. High potassium level 9 days post- op (below yet he knee amputation. Also has cirrhosis (non-alcholoic)...ascites pronounced, some encephalopathy, also diabetic with sugars on the rise since surgery. Meds unsuccessful in lowering K, so had dialysis today. Another booked for tomorrow. Why would he need dialysis two days in a row?