Correct Answer: B — Circuit clotting

CRRT circuit clotting is the most common complication of CRRT in ICU, especially in patients with:

• Hypercoagulable states
• Inadequate anticoagulation
• Low blood flow rates
• High hematocrit

Signs of circuit clotting:

• High filter/transmembrane pressure alarms
• Reduced or absent effluent output
• Dark color of blood in circuit
• Frequent circuit 'down' time

Prevention strategies:

• Regional citrate anticoagulation (RCA): First-line anticoagulation in CRRT (KDIGO 2012)
• Systemic heparin infusion (if no bleeding risk)
• Maintain blood flow rate \(\geq 150-200 \text{ mL/min}\)
• Predilution mode (dilutes blood before filter)

When clotting occurs, the circuit must be changed and anticoagulation reassessed.