A nurse is caring for a patient with acute kidney injury (AKI) who has been receiving continuous renal replacement therapy (CRRT) for 24 hours. Which assessment finding would be the priority concern requiring immediate intervention?

Sudden cessation of blood flow with clotting in the CRRT circuit is a critical emergency that can lead to treatment failure and blood loss, requiring immediate intervention. Other findings (oliguria, hypotension, hyperkalemia) are less urgent in this context.

Understanding the Priority Concern in CRRT

When caring for a patient on continuous renal replacement therapy (CRRT), the nurse must constantly balance the patient's underlying condition with the functional integrity of the extracorporeal circuit. The question asks for the finding that requires the most immediate intervention, which in NCLEX-RN prioritization means identifying the issue that poses the most acute threat to the patient's safety or the viability of the life-sustaining therapy.

Analysis of the Options

* Option 1: Urine output of 25 mL per hour for the past 2 hours.
This represents oliguria, which is an expected clinical manifestation of the underlying acute kidney injury (AKI) that necessitated CRRT. While it requires ongoing monitoring and documentation, it does not represent an acute change or an immediate threat to the patient's life or the therapy itself.

* Option 2: Blood pressure of 90/60 mmHg with baseline of 120/80 mmHg.
Hypotension in a patient on CRRT is a significant concern, as it can be related to excessive fluid removal, bleeding, or the underlying disease process. This requires prompt intervention, such as adjusting ultrafiltration rate or administering fluids. However, in the hierarchy of immediate threats, a mechanical failure of the circuit that halts all therapy is a more time-sensitive emergency.

* Option 3: Sudden stop of blood flow in the CRRT circuit with visible clotting in the filter.
This is the priority finding. A sudden cessation of blood flow with visible clotting indicates a complete circuit thrombosis. This represents a catastrophic failure of the therapy. The circuit must be immediately addressed to prevent further blood loss within the clotted circuit and to re-establish life-sustaining therapy. The patient is receiving no clearance of toxins or volume while the circuit is clotted, and the blood within the circuit is lost. The meta-analysis by Wang et al. (2026) highlights that maintaining adequate anticoagulation is critical, as filter lifespan is directly tied to anticoagulant efficacy and clotting events are a primary reason for circuit failure ^[1]. The immediate nursing action is to stop the blood pump, clamp the lines, and prepare to return the patient's blood if possible, or disconnect and prepare a new circuit.

* Option 4: Serum potassium level of 5.8 mEq/L with normal range of 3.5 to 5.0 mEq/L.
Hyperkalemia is a critical and potentially life-threatening complication of AKI, carrying a risk of fatal cardiac arrhythmias. This value is indeed abnormal and requires urgent medical management, such as administering calcium gluconate, insulin and glucose, or sodium bicarbonate. However, the patient is already on CRRT, which is the definitive treatment for severe hyperkalemia in this context. The therapy itself is actively working to lower the potassium level. In contrast, the sudden clotting of the circuit in option 3 means the treatment for this hyperkalemia (and all other aspects of AKI) has abruptly stopped, making it the more immediate priority to address to restore the therapy that will correct the potassium.

Integrating the Evidence into Clinical Reasoning

The core of this question lies in understanding the concept of circuit patency as a lifeline. The evidence from the provided studies reinforces this. The randomized controlled trial by Li et al. (2025) discusses the goal of achieving a "sufficient anticoagulant effect" during CRRT, which is precisely to prevent the clotting event described in the correct answer . When this anticoagulation fails, the circuit's lifespan ends abruptly. The study by Giani et al. (2026) further emphasizes that the primary goal of anticoagulation strategies like regional citrate anticoagulation is to "prolong circuit lifespan while minimizing bleeding complications" . A sudden clot is the antithesis of this goal, representing a complete and immediate loss of circuit function. While hypotension (option 2) and hyperkalemia (option 4) are serious physiological derangements, they are conditions that can be managed while the CRRT continues to run. The clotted circuit in option 3 is a mechanical failure that stops all management and causes an immediate loss of the patient's blood volume within the circuit, demanding the most rapid nursing response to salvage the situation and prevent further harm.