How should I manage peri‑operative care for a patient with a solitary kidney and chronic kidney disease stage 2 undergoing coronary artery bypass graft surgery?

Perioperative Management for Solitary Kidney with CKD Stage 2 Undergoing CABG

For a patient with a solitary kidney and CKD stage 2 (eGFR 60-89 mL/min/1.73m²) undergoing CABG, strongly consider off-pump CABG to reduce acute kidney injury risk, maintain mean arterial pressure >60 mmHg throughout the perioperative period, use isotonic saline hydration, and avoid all nephrotoxic agents. 1, 2

Preoperative Risk Stratification

Your patient faces elevated risk despite "mild" CKD stage 2:

• Calculate precise eGFR using the CKD-EPI formula preoperatively, as this provides superior predictive capability for postoperative AKI compared to serum creatinine alone 3
• Patients with solitary kidneys have functional reserve limitations that amplify AKI risk even at CKD stage 2 4
• Pre-operative renal impairment increases operative mortality by 35-43% for every 10 mL/min/1.73m² decrease in eGFR 5
• Document baseline eGFR carefully as this predicts six-fold higher risk of postoperative renal deterioration in patients with any degree of pre-existing CKD 4

Surgical Technique Selection

Off-pump CABG is reasonable (Class IIb, Level B) for patients with preoperative renal dysfunction (creatinine clearance <60 mL/min) to reduce acute kidney injury risk 1:

• In patients with eGFR 15-29 mL/min/1.73m², off-pump CABG reduces postoperative dialysis requirement (risk difference 2.79%) 1
• However, balance this against potentially higher graft occlusion rates with off-pump techniques 1
• For CKD stage 2 specifically, the benefit is less pronounced but still reasonable given solitary kidney status 1
• Ensure epiaortic ultrasound scanning (Class IIa, Level B) to evaluate ascending aorta plaque and reduce atheroembolic complications 1

Hemodynamic Management

Maintain mean arterial pressure >60 mmHg throughout the perioperative period to ensure adequate renal perfusion 2:

• Target MAP ≥65-70 mmHg if any hemodynamic instability develops 2
• Use norepinephrine as first-line vasopressor over dopamine, as dopamine increases complications in cardiogenic shock 1
• Target hematocrit >19% during cardiopulmonary bypass to optimize oxygen delivery to the kidney 2
• Optimize heart rate, diastolic pressure, and ventricular end-diastolic pressures to reduce myocardial ischemia 2

Fluid and Volume Management

Administer isotonic saline (0.9% NaCl) starting before procedure and continuing 24 hours post-procedure at 1 mL/kg/hour 6:

• Achieve "dry weight" while maintaining adequate perfusion pressure 2
• Avoid excessive hemodilutional anemia through blood conservation strategies 2
• Monitor urine output, lactate, and clinical assessment beyond MAP alone 2

Beta-Blocker Management

Continue beta-blockers perioperatively if already prescribed, as discontinuation risks rebound hypertension and coronary ischemia 1:

• Beta-blockers improve cardiovascular outcomes in CKD patients undergoing noncardiac surgery, with greatest benefit when eGFR <30 mL/min 1
• Administer intravenously if postoperative ileus prevents oral administration 1
• Similarly, continue clonidine (can use transdermal patch) to avoid rebound hypertension 1

Contrast Exposure Considerations

If recent coronary angiography was performed, consider delaying CABG to assess contrast effect on renal function 2:

• Use low-osmolar or iso-osmolar contrast agents exclusively if any additional imaging needed 6
• Minimize total contrast volume to <350 mL or <4 mL/kg 6
• Pre-procedure high-dose statin (rosuvastatin 40 mg, atorvastatin 80 mg, or simvastatin 80 mg) provides nephroprotection 6

Nephrotoxin Avoidance

Strictly avoid all nephrotoxic agents in the perioperative period 2:

• No NSAIDs for postoperative pain management 2
• No aminoglycosides unless absolutely necessary for specific infections (e.g., enterococcal endocarditis where multi-dose regimens remain standard) 1
• Use lipid formulations of amphotericin B rather than conventional formulations if antifungal therapy needed 1
• Discontinue diuretics, provide sodium loading and volume repletion, and supplement potassium/magnesium if amphotericin required 1

Antiplatelet and Statin Therapy

Continue aspirin and initiate high-dose statin therapy perioperatively 7, 6:

• Oral antiplatelet agents require no dose adjustment for renal function 7
• High-dose statins reduce vascular events and provide nephroprotection 1, 6
• Consider proton pump inhibitor if elevated bleeding risk with dual antiplatelet therapy 7

Postoperative Monitoring

Obtain complete metabolic panel within 48 hours including electrolytes, renal function markers, and complete blood count 2:

• Measure cardiac biomarkers (CK-MB, troponin) in first 24 hours to detect perioperative MI 2
• Monitor for adequate organ perfusion: urine output, lactate, clinical assessment 2
• Persistent renal function decline >10% from baseline associates with 7.3-fold higher mortality risk 6

Long-Term Follow-Up

Patients with severe AKI after CABG require regular monitoring for long-term renal deterioration 8:

• Among CABG patients requiring acute dialysis, 38.9% of survivors develop CKD progression (dialysis dependence or doubling of creatinine) 8
• Even without dialysis requirement, 23% of patients with pre-existing CKD develop further renal impairment postoperatively 4
• Hospital stay averages 2.4 days longer in patients with postoperative renal impairment 4

Critical Pitfalls to Avoid

• Do not assume normal coagulation even on non-dialysis days, as platelet dysfunction persists in uremia despite normal platelet counts 2
• Do not rely on serum creatinine alone for renal assessment—always calculate eGFR 4, 3
• Do not use dopamine as first-line vasopressor—norepinephrine is superior 1
• Do not withhold statins due to concerns about contrast-induced nephropathy—they are protective 6