Preoperative Evaluation of Patients with Renal Dysfunction

🎯 Goals of Preoperative Evaluation

  1. Assess the severity and type of renal impairment (AKI vs CKD)
  2. Evaluate end-organ effects of uremia
  3. Optimize fluid, electrolyte, and acid-base status
  4. Adjust medication dosing and plan for nephrotoxic agents
  5. Plan dialysis timing if required
  6. Anticipate anesthesia-related complications


🔬 1. Detailed History

Focus Area

What to Ask / Look For

Cause of renal dysfunction

Diabetes, hypertension, glomerulonephritis, obstructive uropathy

Dialysis history

Hemodialysis (HD) vs Peritoneal dialysis (PD), last session, vascular access, dry weight

Uremic symptoms

Nausea, vomiting, pruritus, fatigue, confusion, anorexia

Volume status

Thirst, orthopnea, pedal edema, weight gain/loss

Comorbidities

Cardiovascular disease (common), DM, anemia, bone disease

Medications

Nephrotoxics (NSAIDs, aminoglycosides), ACE/ARBs, diuretics, insulin



🧍‍♂️ 2. Physical Examination

  • Volume status
    • Dry mucosa, low JVP → hypovolemia
    • Edema, raised JVP, rales → fluid overload
  • Cardiovascular
    • Pericardial rub (uremic pericarditis)
    • BP: Hypertension is common; hypotension in volume-depleted
  • Neurological
    • Confusion, lethargy, seizures (uremic encephalopathy)
  • Signs of anemia – Pallor, fatigue
  • Signs of bone disease – Bone tenderness, deformities (in advanced CKD)


🧪 3. Laboratory Evaluation

Test

Interpretation & Importance

Serum Creatinine & BUN

For GFR estimation; BUN > 60 mg/dL → uremic symptoms

eGFR (CKD-EPI)

Classify CKD stages (G1–G5)

Electrolytes

Hyperkalemia, hyponatremia, hyperphosphatemia

Calcium & Phosphate

↓ Ca²⁺, ↑ PO₄³⁻ common in CKD

ABG

Metabolic acidosis (non-anion gap or high anion gap)

CBC

Anemia (normocytic, normochromic), platelets for bleeding risk

LFTs, glucose

Assess for comorbidities

Coagulation profile

Uremia-induced platelet dysfunction, INR if liver disease

ECG

Look for peaked T-waves, arrhythmias (hyperkalemia)

CXR

Pulmonary edema, pleural effusion in fluid overload

ECHO

LVH, systolic/diastolic dysfunction, pericardial effusion



🧫 4. Classification of CKD (Based on KDIGO Guidelines)

Stage

eGFR (mL/min/1.73 m²)

Clinical Implication

G1

≥ 90

Normal or high GFR, but other evidence of CKD

G2

60–89

Mild ↓ GFR

G3a

45–59

Moderate ↓

G3b

30–44

Moderate-severe ↓

G4

15–29

Severe ↓

G5

< 15

Kidney failure (often dialysis-dependent)



💊 5. Medication Review & Adjustments

Drug Type

Adjustment Needed

Nephrotoxic drugs

Avoid NSAIDs, aminoglycosides, contrast agents

Water-soluble opioids

Prefer fentanyl/remifentanil over morphine

Muscle relaxants

Cisatracurium preferred (organ-independent)

Sedatives

Midazolam may accumulate; titrate carefully

Insulin/oral antidiabetics

Reduce dose (↓ renal clearance)

Antihypertensives

Hold ACEi/ARBs on surgery day to avoid hypotension



🫀 6. Cardiovascular Risk Assessment

CKD is a cardiovascular risk equivalent.

  • ECG and ECHO mandatory if reduced EF, valvular disease suspected
  • Consider stress testing or cardiology clearance in moderate-high risk
  • Optimize BP preoperatively (target: < 140/90 mmHg)


🧃 7. Volume & Electrolyte Optimization

  • Hyperkalemia
    • Treat if K⁺ > 5.5 mEq/L or ECG changes
    • Insulin + glucose, calcium gluconate, salbutamol, dialysis
  • Acidosis
    • NaHCO₃ if severe (< 7.2); avoid overcorrection
  • Fluid status
    • Avoid both overload and hypovolemia
    • Use balanced crystalloids (Plasma-Lyte or NS cautiously)


🩸 8. Hematologic Evaluation

  • Anemia common in CKD
    • Hb < 10 g/dL → Consider ESA, iron, blood transfusion
  • Platelet dysfunction due to uremia
    • Risk of bleeding despite normal platelet count
    • DDAVP (0.3 mcg/kg) can be given pre-op if bleeding risk
  • Avoid regional anesthesia if uremic bleeding risk persists


🧼 9. Dialysis Planning

Dialysis Status

Recommendation

On maintenance HD

Dialyze within 24 hrs pre-op (preferably same day)

Peritoneal dialysis

Drain abdomen before GA; watch for hypercarbia, aspiration

Not on dialysis yet

Consider nephrology consult if GFR < 15 mL/min/1.73 m²


Monitor:

  • Dry weight
  • Electrolytes (especially K⁺, Na⁺)
  • Volume status


🚫 Red Flags Needing Optimization Before Elective Surgery

✅ K⁺ > 5.5 mEq/L
✅ Severe metabolic acidosis (pH < 7.2)
✅ Pulmonary edema / CHF
✅ Active uremic symptoms (encephalopathy, pericarditis)
✅ Severe anemia (Hb < 8 g/dL)
✅ Coagulopathy not corrected