What is the prescribed treatment for a patient with acute kidney injury, normal hematocrit, and hypotension, requiring Continuous Veno-Venous Hemodiafiltration (CVVHDF)?

Treatment for AKI with Hypotension Requiring CVVHDF

For a patient with acute kidney injury, normal hematocrit, and hypotension requiring CVVHDF, the prescribed treatment includes: immediate fluid resuscitation with crystalloids (avoiding hyperchloremic solutions), norepinephrine as the first-line vasopressor, CVVHDF at an effluent dose of 20-25 mL/kg/hour with bicarbonate-based replacement fluid and regional citrate anticoagulation, and aggressive management of negative fluid balance once hemodynamically stable. 1

Immediate Hemodynamic Management

Fluid Resuscitation

• Administer intravenous crystalloid fluids immediately to correct volume depletion before or concurrent with vasopressor initiation 1
• Avoid hyperchloremic crystalloid solutions when possible, as observational data suggest potential harm, though this requires confirmation in randomized trials 1
• Blood volume depletion must be corrected as fully as possible before vasopressor administration, though in emergency situations vasopressors can be given concurrently with volume replacement 2

Vasopressor Selection

• Use norepinephrine as the first-line vasopressor agent 1
• Avoid dopamine as first-line therapy, as it is associated with increased mortality in septic shock and increased adverse events including arrhythmias 1
• Start norepinephrine at 0.5 mg/hour via continuous IV infusion, increasing by 0.5 mg/hour every 4 hours to a maximum of 3 mg/hour 1
• Target mean arterial pressure increase of ≥10 mm Hg to maintain perfusion to vital organs 1
• In previously hypertensive patients, raise blood pressure no higher than 40 mm Hg below pre-existing systolic pressure 2

Critical Pitfall: Never use norepinephrine as the sole treatment for hypotension from volume depletion without concurrent fluid resuscitation, as this causes severe peripheral vasoconstriction, decreased renal perfusion, tissue hypoxia, and lactate acidosis 2

CVVHDF Prescription

Modality and Dosing

• CVVHDF is the appropriate modality for hemodynamically unstable patients, providing superior hemodynamic tolerance compared to intermittent hemodialysis 1, 3
• Deliver an effluent volume of 20-25 mL/kg/hour 1, 4, 3
• Higher doses (35-40 mL/kg/hour) provide no mortality benefit based on the RENAL and ATN trials 1
• Prescribe higher than target dose initially, as delivered dose often falls short of prescribed dose 1

Replacement Fluid Composition

• Use bicarbonate-based replacement fluid rather than lactate-based solutions 1, 4, 3
• Bicarbonate is particularly important in patients with shock, as lactate metabolism may be impaired 1, 3
• Bicarbonate has replaced lactate and acetate as the buffer of choice for continuous RRT 1

Anticoagulation Strategy

• Regional citrate anticoagulation is recommended as first-line therapy if no contraindications exist 1, 4, 3
• Citrate is not FDA-approved for CRRT anticoagulation in the US, but simpler and safer protocols have increased its acceptance 1
• For patients with heparin-induced thrombocytopenia, use direct thrombin inhibitors (argatroban) or Factor Xa inhibitors 3
• Use minimal or no anticoagulation in patients with active bleeding or high bleeding risk 3

Vascular Access

• Insert an uncuffed non-tunneled dialysis catheter of adequate length and gauge 1, 4, 3
• Preferred site order: right internal jugular vein (first choice), femoral vein, left internal jugular vein, subclavian vein (last choice due to stenosis risk) 1, 4, 3
• Always use ultrasound guidance for catheter insertion 1, 4, 3
• Obtain chest radiograph to confirm line placement before first use of internal jugular or subclavian catheters 1, 4

Fluid Balance Management

Target Negative Fluid Balance

• Achieve negative daily fluid balance during CVVHDF once hemodynamically stable 5
• Positive daily fluid balance during CRRT is independently associated with increased mortality (OR = 4.55) 5
• CVVHDF facilitates management of fluid balance in hemodynamically unstable patients better than intermittent modalities 1, 3
• Monitor cumulative fluid balance closely, targeting progressive negative balance after initial resuscitation 5

Monitoring Parameters

• Assess vital signs hourly and evaluate for hypotension 4
• Monitor electrolytes and acid-base status every 2-4 hours initially 4
• Measure pre- and post-treatment weights 4
• Track urine output if any residual kidney function remains 4
• Oliguria (<500 mL for 12 hours) before CVVHDF initiation is an independent mortality risk factor (OR = 2.1) 6

Nutritional Support

Protein Requirements

• Provide 1.2-1.3 g protein/kg/day minimum for maintenance dialysis patients 1
• Consider higher protein intake (1.5-2.5 g/kg/day) for catabolic, acutely ill patients receiving intensive dialysis 1
• CVVHDF removes approximately 5-12 g of amino acids per day in patients receiving nutritional support 1
• Protein intakes >1.2-1.3 g/kg/day are better tolerated with more intensive dialysis like CVVHDF 1

Energy Requirements

• Provide 30-35 kcal/kg/day for acutely ill maintenance dialysis patients 1
• Include energy provided by dextrose uptake from dialysate when calculating total energy intake 1
• Institute tube feeding, intradialytic parenteral nutrition, or total parenteral nutrition if oral intake is inadequate 1

Transition Planning

When to Transition from CVVHDF

• Consider transitioning to intermittent hemodialysis when: vasopressor support is discontinued, hemodynamic stability is achieved, intracranial hypertension (if present) has resolved, and positive fluid balance can be controlled by intermittent therapy 1, 3
• Sustained hemodiafiltration (S-HDF) may be used as a transition modality, delivering treatment daily for 6.5 hours with dialysate flow of 300-500 mL/min 7, 8
• S-HDF may accelerate renal recovery compared to conventional CVVHDF 8

Discontinuation Criteria

• Discontinue RRT when kidney function has recovered or when RRT becomes inconsistent with shared care goals 1
• Kidney recovery is defined as sustained independence from RRT for a minimum of 14 days 1, 9
• Assess renal recovery weekly with pre-dialysis creatinine and residual kidney function measurements if dialysis continues beyond 14 days 4

Medications to Avoid

• Do not use diuretics to treat AKI except for volume overload management (Grade 2C) 1
• Do not use low-dose dopamine to prevent or treat AKI (Grade 1A) 1
• Do not use fenoldopam to prevent or treat AKI (Grade 2C) 1
• Do not use atrial natriuretic peptide to treat AKI (Grade 2B) 1
• Avoid aminoglycosides unless no suitable less nephrotoxic alternatives are available (Grade 2A) 1