Anesthesia Considerations for a Patient with eGFR of 34
Patients with impaired renal function (eGFR of 34) require specific anesthesia modifications to prevent further renal deterioration and reduce perioperative complications. 1
Preoperative Assessment and Preparation
Renal function evaluation: An eGFR of 34 mL/min/1.73m² indicates moderate chronic kidney disease (CKD stage 3b)
Blood pressure management:
Medication management:
- ACE inhibitors/ARBs: Hold these medications 24-48 hours before surgery to prevent intraoperative hypotension and acute kidney injury 1, 2
- Metformin: Discontinue at least 24 hours before surgery due to risk of lactic acidosis 1
- NSAIDs: Strictly avoid in patients with eGFR <30-60 mL/min due to risk of further kidney injury 3
- Diabetic medications: Hold non-insulin oral agents on the morning of surgery 1
Intraoperative Management
Hemodynamic Monitoring and Targets
- Implement intra-arterial blood pressure monitoring before induction to detect and treat hypotension promptly 1
- Maintain mean arterial pressure between 60-70 mmHg, or >70 mmHg if the patient is hypertensive 1
- Avoid hypotension defined as >20% drop from baseline systolic blood pressure 1
- Consider advanced hemodynamic monitoring for major or high-risk surgery to guide fluid therapy and vasopressor use 1
Fluid Management
- Administer fluids with caution in divided boluses to assess response 1
- Avoid volume overload as patients with impaired renal function may have reduced cardiovascular reserve 4
- Monitor urine output but recognize it may not accurately reflect renal perfusion in CKD
Anesthetic Agent Selection
- Adjust anesthetic dosing: Patients with renal impairment often require lower doses due to altered pharmacokinetics 5, 6
- Consider depth of anesthesia monitoring (BIS/entropy) to prevent overdosing 1
- Preferred agents:
- Inhalational agents: All modern volatile anesthetics are acceptable; sevoflurane at fresh gas flows >1 L/min is safe 2
- Local anesthetics: Lidocaine and mepivacaine can be safely used 1
- Opioids: Avoid medications with active metabolites that depend on renal clearance
- Muscle relaxants: Adjust dosing and monitor neuromuscular function carefully 5
Nephrotoxin Avoidance
- Strictly avoid nephrotoxic drugs during the perioperative period 1
- Avoid aminoglycoside antibiotics and tetracyclines 1
- Limit contrast media exposure if imaging is required
Postoperative Care
- Continue hemodynamic monitoring in the recovery period
- Maintain adequate hydration while avoiding volume overload
- Monitor renal function with serial creatinine measurements
- Resume ACE inhibitors/ARBs only after confirming stable renal function and hemodynamics 1
- Pain management: Avoid NSAIDs; use acetaminophen, carefully dosed opioids, or regional analgesia techniques 3, 4
Special Considerations
- Regional anesthesia may be beneficial as it can reduce the incidence of postoperative renal failure, particularly thoracic epidural for major surgeries 2
- Antibiotic prophylaxis: Adjust dosing based on renal function; consult with nephrology if needed 1
- Electrolyte management: Monitor potassium, calcium, and magnesium levels closely
Common Pitfalls to Avoid
- Failing to hold ACE inhibitors/ARBs preoperatively, which can lead to severe hypotension during anesthesia
- Inadequate blood pressure monitoring during induction, when significant hypotension can occur
- Administering nephrotoxic drugs that can worsen renal function
- Overhydration in an attempt to maintain urine output
- Inappropriate dosing of medications that depend on renal clearance
By carefully managing these considerations, the risk of perioperative acute kidney injury and other complications can be significantly reduced in patients with impaired renal function.