Explanation

A serum potassium level of 6.5 mEq/L, indicating severe hyperkalemia, is the most concerning finding in a patient with acute kidney injury (AKI). Hyperkalemia is a potentially life-threatening complication of AKI that requires immediate attention.

Severe hyperkalemia (potassium > 6.5 mEq/L) can lead to cardiac arrhythmias, including ventricular fibrillation and asystole. It can cause characteristic ECG changes, including peaked T waves, widened QRS complexes, and eventually, sine wave pattern preceding cardiac arrest.

While a slight decrease in urine output, mild elevation in serum creatinine, and complaints of nausea are all potential findings in AKI, they are not as immediately life-threatening as severe hyperkalemia.

The nurse should immediately report this potassium level to the physician. Treatment may include administration of calcium gluconate to stabilize cardiac membranes, insulin with glucose to shift potassium intracellularly, sodium bicarbonate if metabolic acidosis is present, and possibly emergent dialysis.

Nurses caring for patients with AKI should be vigilant in monitoring electrolyte levels, particularly potassium, and be prepared to act quickly in cases of severe hyperkalemia.