What are the recommendations for a 72-year-old female Intensive Care Unit (ICU) patient with Diabetic Ketoacidosis (DKA), hyperglycemia, hypernatremia, normokalemia, metabolic acidosis, elevated creatinine, impaired renal function, oliguria, lactic acidosis, hyperphosphatemia, normal calcium levels, and hypomagnesemia, who is planned for Continuous Renal Replacement Therapy (CRRT)?

Management of DKA with AKI Requiring CRRT in a Critically Ill Patient

This 72-year-old ICU patient with severe DKA, acute kidney injury, and hemodynamic instability requires immediate initiation of CRRT with specific attention to insulin therapy, electrolyte management, and fluid composition tailored to prevent life-threatening complications during renal replacement therapy.

Immediate CRRT Initiation and Modality Selection

CRRT is the appropriate modality for this hemodynamically unstable patient with oliguria and severe metabolic derangements. 1 The patient's oliguria (50 cc/hour), elevated creatinine (3.5), and lactic acidosis (3.8) with hypernatremia (152) indicate severe AKI requiring urgent renal support. 2

• Use continuous venovenous hemodiafiltration (CVVHDF) or hemofiltration (CVVHF) rather than intermittent hemodialysis given the hemodynamic instability implied by lactic acidosis and severe metabolic derangements. 1, 2
• Target effluent dose of 20-25 mL/kg/hour for adequate solute clearance and metabolic control. 1, 3
• Use bicarbonate-buffered dialysate/replacement fluid (not lactate) given the lactic acidosis (3.8) and metabolic acidosis (CO2 15, anion gap 15). 1 Lactate-buffered solutions would worsen acidosis in this patient with impaired lactate metabolism. 1

Critical Insulin Management During CRRT

Insulin therapy must be carefully titrated with close glucose monitoring as CRRT will affect insulin requirements and glucose control. 2, 4

• Target plasma glucose of 110-149 mg/dL (6.1-8.3 mmol/L) using continuous IV insulin infusion. 2 Avoid tight glycemic control (80-110 mg/dL) as this increases hypoglycemia risk without mortality benefit. 2
• Monitor blood glucose hourly initially as CRRT initiation may rapidly lower glucose levels, requiring insulin dose reduction. 4
• Anticipate decreased insulin requirements once CRRT begins due to improved clearance of counter-regulatory hormones and correction of acidosis. 4
• Watch for hypoglycemia warning signs (altered mental status, tachycardia) which may be blunted in critically ill sedated patients. 4

Electrolyte Management Strategy

Electrolyte abnormalities require aggressive monitoring and customized CRRT fluid composition to prevent life-threatening complications. 2, 5, 6

Potassium Management

• Monitor potassium every 2-4 hours initially despite current normal level (4.6), as insulin therapy and correction of acidosis will drive potassium intracellularly, causing potentially severe hypokalemia. 4, 5
• Use potassium-containing dialysate (2-4 mEq/L) to prevent hypokalemia during CRRT. 2, 6 Standard potassium-free solutions will cause dangerous hypokalemia in this setting. 2
• Hypokalemia can cause respiratory paralysis, ventricular arrhythmias, and death when insulin is administered, requiring immediate recognition and treatment. 4

Phosphate Management

• Current hyperphosphatemia (6.4) will rapidly reverse to hypophosphatemia once CRRT begins and insulin drives phosphate intracellularly. 2, 5
• Monitor phosphate levels every 6-12 hours as hypophosphatemia occurs in 60-80% of ICU patients on CRRT. 2
• Use phosphate-containing dialysate solutions to prevent severe hypophosphatemia, which is associated with worse outcomes. 2, 6

Magnesium Management

• Current hypomagnesemia (Mg 3, assuming 3 mg/dL = 1.23 mmol/L, still low-normal) will worsen with CRRT. 2
• Use magnesium-containing dialysate as magnesium losses during CRRT are substantial, especially with citrate anticoagulation. 2
• Monitor magnesium levels daily as hypomagnesemia occurs in 60-65% of critically ill patients on CRRT. 2

Sodium and Osmolality Management

• Severe hypernatremia (152) requires slow, controlled correction to avoid cerebral edema. 2, 5
• CRRT allows gradual sodium correction (target 0.5 mEq/L/hour maximum) which is safer than intermittent hemodialysis. 2
• Use dialysate sodium concentration of 140-145 mEq/L to avoid overly rapid correction. 5, 6

Anticoagulation Strategy

Regional citrate anticoagulation is first-line for CRRT unless contraindicated. 1

• Use regional citrate anticoagulation rather than heparin given the metabolic instability and potential coagulopathy in DKA. 1
• Monitor ionized calcium closely (every 4-6 hours) as citrate chelates calcium and this patient already has low calcium (7, likely mg/dL = 1.75 mmol/L). 1, 2
• Citrate may accumulate given liver dysfunction implied by lactic acidosis; monitor citrate accumulation by checking total calcium/ionized calcium ratio. 1

Vascular Access

Obtain appropriate vascular access immediately for CRRT initiation. 1

• Use ultrasound-guided placement of uncuffed, non-tunneled dialysis catheter in the right internal jugular vein as first choice. 1
• Obtain chest X-ray before first use if internal jugular or subclavian site used. 1
• Avoid femoral access if possible in this patient with severe metabolic derangements requiring optimal flow rates. 1

Nutritional Considerations During CRRT

Protein and micronutrient requirements increase substantially during CRRT. 2, 3

• Provide 1.5-1.7 g/kg/day protein once hemodynamically stable, as CRRT causes continuous amino acid losses (10-15 g/day). 2, 3
• Target total energy intake of 20-30 kcal/kg/day to prevent catabolism. 2
• Supplement water-soluble vitamins (especially thiamine, folate, vitamin C) as CRRT causes massive losses. 2 Thiamine deficiency can worsen lactic acidosis. 2
• Monitor and replace copper if CRRT continues beyond 2 weeks (3 mg/day IV). 2

Monitoring Protocol

Intensive monitoring is essential to prevent complications during CRRT in DKA. 2, 1, 4

• Blood glucose: Hourly until stable, then every 2-4 hours 2, 4
• Potassium: Every 2-4 hours initially, then every 4-6 hours 4, 2
• Phosphate: Every 6-12 hours 2
• Magnesium: Daily 2
• Calcium (ionized): Every 4-6 hours if using citrate 1, 2
• Sodium: Every 4-6 hours to monitor correction rate 5
• Acid-base status: Every 4-6 hours until stable 5
• CRRT delivered dose: Continuously monitor to ensure target 20-25 mL/kg/hour is achieved 1

Critical Pitfalls to Avoid

• Do not use lactate-buffered CRRT solutions in this patient with lactic acidosis—use bicarbonate only. 1
• Do not use standard electrolyte-free dialysate—this will cause life-threatening hypokalemia and hypophosphatemia during insulin therapy and CRRT. 2, 4, 6
• Do not correct hypernatremia too rapidly—risk of cerebral edema is high. 2, 5
• Do not delay CRRT initiation—oliguria with severe metabolic derangements requires immediate intervention before complications develop. 2, 1
• Do not use cellulose-based membranes—use biocompatible synthetic membranes to reduce inflammatory activation. 1