A nurse is caring for a patient with acute kidney injury (AKI) in the oliguric phase. Which nursing intervention should be the highest priority?

Acute Kidney Injury represents a sudden decline in kidney function, leading to the accumulation of waste products and the inability to regulate fluid and electrolyte balance. The clinical course often includes an oliguric phase, characterized by a urine output of less than 400 mL/day. During this phase, the kidneys have lost their ability to effectively filter blood and excrete fluid. The underlying pathophysiology involves tubular damage, intratubular obstruction, and reduced glomerular filtration rate. Because the kidneys cannot remove excess volume, continuing to add fluid to the system without careful monitoring can rapidly lead to fluid volume overload, a critical complication that can precipitate hypertension, pulmonary edema, and heart failure. The Brazilian Society of Nephrology guidelines emphasize that managing these patients requires meticulous attention to hemodynamic and volume status, as the nephrologist's role includes preventing iatrogenic complications from fluid mismanagement ^[1].

The highest priority nursing intervention is to monitor strict intake and output (I&O) with fluid restriction. This is a cornerstone of non-dialysis kidney support therapy. The rationale is grounded in the principle of balancing fluid intake with the patient's drastically reduced output and insensible losses. Accurate I&O monitoring provides the essential data needed to guide fluid prescription and prevent overload. Fluid restriction is typically calculated to replace only insensible losses (from skin and respiration, roughly 500-600 mL/day) plus the volume of any measurable output (urine, vomitus, diarrhea). This precise management is a direct application of volume management principles, which are critical for patients with kidney dysfunction to avoid the cascading negative effects of hypervolemia on both cardiac and renal function ^[2].

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  Option 1: Encourage increased fluid intake to promote kidney function. This is contraindicated in the oliguric phase of AKI. The primary problem is not a lack of fluid, but the kidney's inability to process it. Forcing fluids will not "flush out" the kidneys; instead, it will dangerously expand the intravascular volume, leading to dilutional hyponatremia, hypertension, and pulmonary edema. The goal is to maintain euvolemia, not to challenge the already injured kidneys with a fluid load they cannot handle.
  


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  Option 2: Administer diuretics to increase urine output. While loop diuretics like furosemide are sometimes used in AKI, their role is primarily to manage fluid overload, not to treat the underlying kidney injury or improve kidney function. In the oliguric phase, the tubules are often unresponsive to diuretics. Administering them is a medical, not an independent nursing, intervention and is not the highest initial priority. The priority nursing action is to first establish a strict monitoring baseline to determine the severity of fluid imbalance before any pharmacological intervention is considered. Evidence suggests that diuretic use does not improve patient-centered outcomes like mortality or renal recovery in AKI.
  


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  Option 3: Provide a high-protein diet to prevent muscle wasting. This is incorrect for the oliguric phase. A high-protein diet increases the production of nitrogenous waste products (blood urea nitrogen), which the injured kidneys cannot effectively excrete. This exacerbates azotemia and uremia. Nutritional therapy in AKI is carefully calibrated; during the oliguric phase, the focus is on providing adequate calories from carbohydrates and fats to prevent catabolism while restricting protein to minimize uremic toxin buildup. Once the patient enters the diuretic phase or begins dialysis, protein intake is liberalized.
  

The synthesis of evidence from the guidelines and the volume management summary reinforces that fluid control is the linchpin of AKI management. The hospital nephrology assistance guide details that non-dialysis supportive care, which is largely nurse-driven, centers on strict hemodynamic and fluid balance monitoring to prevent iatrogenic volume overload ^[1]. This aligns directly with the best-practice evidence for volume management in patients with complex cardiac and renal comorbidities, which emphasizes a systematic, evidence-based approach to fluid assessment and restriction to prevent decompensation ^[2]. For the NCLEX-RN examinee, this scenario tests the ability to recognize that in a state of severely impaired excretion, restricting intake is a fundamental safety principle that takes precedence over promoting intake, stimulating output with medications, or increasing metabolic waste production through diet. The nurse's role is to protect the patient from the immediate, life-threatening consequence of fluid overload.