Preoperative Management of Patients with Multiple Metabolic Abnormalities

Critical Preoperative Issues Requiring Attention

The American College of Cardiology recommends that patients with chronic kidney disease (CKD) Stage 3b are at increased risk for perioperative cardiac complications and acute kidney injury, with a creatinine level of 1.78 mg/dL and BUN of 44 mg/dL representing an independent risk factor 1.
The American College of Cardiology also notes that preoperative creatinine >2 mg/dL is a significant independent risk factor for cardiac complications after major noncardiac surgery 1.
The American Family Physician suggests that electrolyte and creatinine testing is indicated in patients over 40 years old with hypertension and chronic kidney disease 2.
The American Family Physician also recommends that the elevated BUN/creatinine ratio suggests a prerenal component that may be reversible with hydration 2.
The Anaesthesia journal recommends that perioperative hemodynamic optimization should target mean arterial pressure of 60-70 mmHg, or >70 mmHg if the patient is hypertensive, to maintain renal perfusion pressure 3.

The American Diabetes Association recommends that the A1C goal for elective surgeries should be <8% whenever possible, and this must be measured preoperatively to evaluate long-term glycemic control 4.
The American Diabetes Association also recommends that the blood glucose goal in the perioperative period should be 100-180 mg/dL, with monitoring at least every 2-4 hours while NPO 4.
The Diabetes Care journal recommends that if the patient is on metformin, it should be held on the day of surgery only 4.
The Diabetes Care journal also recommends that if the patient is on SGLT2 inhibitors, these must be discontinued 3-4 days before surgery to prevent life-threatening euglycemic diabetic ketoacidosis 4.
The World Journal of Emergency Surgery recommends that perioperative glycemic control in the range of 7.7-10 mmol/L (140-180 mg/dL) is recommended, preferably with a variable rate insulin infusion 5.

The Journal of the American College of Cardiology recommends that the hemoglobin of 12.9 g/dL is just below the normal range and represents mild anemia, which imposes stress on the cardiovascular system and may exacerbate myocardial ischemia 1.
The Journal of the American College of Cardiology also notes that hematocrits <28% are associated with increased perioperative ischemia and complications, but this patient's hematocrit of 38.3% is acceptable for surgery 1.

The Diabetes Care journal recommends that medication adjustments should include discontinuing SGLT2 inhibitors 3-4 days before surgery, holding metformin on the day of surgery, and holding other oral hypoglycemics morning of surgery 4.
The Anaesthesia journal recommends that perioperative monitoring should include maintaining MAP 60-70 mmHg (or >70 mmHg if hypertensive) and avoiding nephrotoxic agents 3.

The American Family Physician recommends that routine urinalysis should not be performed in asymptomatic patients, but this patient's proteinuria and hematuria are clinically significant findings that require attention 2.
The JAMA Surgery journal recommends that NSAIDs should not be used for postoperative pain control given the renal dysfunction 6.

Serum creatinine > 2 mg/dL identifies CKD patients at significantly increased peri‑operative risk and mandates enhanced monitoring and optimization before elective surgery (ACC/AHA guidelines) 7.
Creatinine > 2 mg/dL is an independent predictor of cardiac complications after major non‑cardiac surgery, prompting heightened peri‑operative vigilance (ACC/AHA) 8.
In patients > 70 years, creatinine > 2.6 mg/dL markedly raises the risk of requiring chronic dialysis after cardiac surgery (ACC/AHA) 7.

Calculate estimated GFR with the MDRD (or equivalent) equation rather than relying on serum creatinine alone to obtain a more accurate assessment of renal function (ACC/AHA) 8.
Incorporate age‑ and weight‑adjusted creatinine clearance for superior risk prediction compared with creatinine alone (ACC/AHA) 7.
A BUN‑to‑creatinine ratio > 20:1 suggests prerenal azotemia from volume depletion, heart failure, or medication effects; these reversible factors should be corrected before surgery (ACC/AHA) 8.

For patients with creatinine 1.5–2.0 mg/dL, surgery may proceed with enhanced monitoring but without an absolute contraindication (ACC/AHA) 7.
Do not discontinue ACE inhibitors or ARBs solely because of modest BUN/creatinine elevations; small increases are not an indication for cessation in heart‑failure patients (ACC/AHA) 8.

Ensure adequate dialysis before surgery: target weekly Kt/V ≥ 2.0 for peritoneal dialysis or single‑pool spKt/V ≈ 1.2 for hemodialysis (American Journal of Kidney Diseases) 9.
Schedule the operation for the day after a dialysis session when feasible to optimize volume status and minimize uremic toxins (American Journal of Kidney Diseases) 9.

Aim for pre‑operative HbA1c < 8% and maintain peri‑operative glucose between 100–180 mg/dL (Diabetes Care) 10.
Hold metformin on the day of surgery and discontinue SGLT2 inhibitors 3–4 days pre‑operatively to prevent euglycemic ketoacidosis (Diabetes Care) 10.

Use serum creatinine > 2 mg/dL and eGFR < 45 mL/min/1.73 m² as trigger thresholds for comprehensive peri‑operative planning, nephrology consultation, and renal‑protective measures (ACC/AHA) 7.