All of the following can contribute to postoperative hyperkalemia except:

Postoperative hyperkalemia can be influenced by several factors related to the body’s ability to excrete potassium. Among those listed, effective renal function is critical in maintaining potassium balance. When renal function is effective, the kidneys are capable of filtering blood and excreting excess potassium, helping to prevent hyperkalemia.

In contrast, a low cardiac output state, the use of ACE inhibitors, and acute renal failure all impair the body’s ability to manage potassium levels. A low cardiac output state can reduce renal perfusion, leading to decreased potassium excretion. ACE inhibitors can lead to elevated potassium levels by inhibiting the renin-angiotensin-aldosterone system, which is responsible for potassium elimination via the kidneys. Acute renal failure directly impairs kidney function, leading to reduced potassium excretion and consequent hyperkalemia.

Thus, effective renal function stands out as the factor that does not contribute to postoperative hyperkalemia, as it allows for proper potassium regulation and excretion.