What are the preoperative management recommendations for a patient with diabetic retinopathy, impaired renal function, and a benign uterine myoma (uterine fibroid) scheduled for operation?

Preoperative Management for Diabetic Patient with Retinopathy, Renal Impairment, and Uterine Fibroid

This patient requires comprehensive preoperative assessment focusing on glycemic control, cardiovascular risk stratification (particularly for silent myocardial ischemia and cardiac autonomic neuropathy), renal function optimization, and medication adjustments to minimize perioperative morbidity and mortality. 1

Glycemic Assessment and Control

• Measure HbA1c and recent capillary blood glucose levels to assess current glycemic control, targeting preoperative blood glucose < 180 mg/dL (10 mmol/L) to decrease risk of death, infection, and complications 1
• Adjust antidiabetic medications accordingly before surgery, recognizing that optimal glycemic control (HbA1c < 7%) slows progression of microvascular complications including retinopathy and nephropathy 1, 2
• The presence of diabetic retinopathy indicates established microvascular disease and signals high risk for concurrent nephropathy and cardiac autonomic neuropathy, requiring heightened vigilance 1

Cardiovascular Risk Assessment

Given diabetic retinopathy (a marker of microvascular disease), this patient requires specific cardiac evaluation for silent myocardial ischemia and cardiac autonomic neuropathy (CAN), both of which dramatically increase perioperative cardiovascular risk. 1

Silent Myocardial Ischemia Screening

• Obtain detailed cardiovascular history including: coronary disease, prior revascularization, atypical angina symptoms (dyspnea, epigastric pain), orthostatic hypotension, and episodes of unrecognized hypoglycemia 1
• Perform ECG looking specifically for ischemic changes, tachycardia, arrhythmia, and prolonged QTc interval (> 440 ms) 1
• If Lee (revised cardiac risk index) score ≥ 2 AND functional capacity < 4 METs, refer to cardiology for ischemia testing before proceeding with surgery 1
• Silent heart disease should be suspected with high cardiovascular risk, particularly with other arterial damage, macroproteinuria, renal failure, or coronary calcium score > 400 Agatston units 1

Cardiac Autonomic Neuropathy (CAN) Assessment

CAN is critically important to identify preoperatively because it increases risk of cardiovascular events and sudden death. 1

• Suspect CAN if any of the following are present: permanent tachycardia, QTc > 440 ms, myocardial ischemia, orthostatic or postprandial hypotension, serious unfelt hypoglycemia, absence of nocturnal blood pressure decrease 1
• When microangiopathic complications exist (retinopathy, nephropathy), actively investigate for CAN using heart rate variation tests including deep respiration test and orthostatic testing 1
• If CAN is confirmed by two abnormal tests OR is symptomatic/complicated, plan for intra- and postoperative monitoring in a high dependency unit 1

Renal Function Evaluation and Management

Measure glomerular filtration rate (GFR) preoperatively, as chronic diabetic kidney disease (DCKD) significantly aggravates the risk of perioperative acute renal failure. 1, 2

Renal Assessment

• Calculate estimated GFR using MDRD, CKD-EPI, or Cockcroft-Gault formula if patient is stable 1
• Measure albumin/creatinine ratio (ACR) to assess severity of diabetic nephropathy 2
• The presence of diabetic retinopathy strongly suggests concurrent nephropathy, as these microvascular complications typically progress together, particularly in Type 1 diabetes 1
• Recognize that diabetes is an independent risk factor for perioperative acute renal failure, with DCKD further increasing this risk 1

Renal Protection Strategy

• Optimize blood pressure control targeting < 140/85-90 mmHg using ACE inhibitors or ARBs preferentially, as these reduce albuminuria and slow GFR decline 1, 2
• Ensure HbA1c < 7% to slow nephropathy progression 1, 2
• Add statin therapy if not already prescribed to reduce albuminuria and slow GFR decline 1, 2
• Plan intraoperative hemodynamic monitoring to maintain mean arterial pressure 60-70 mmHg (or > 70 mmHg if hypertensive) to preserve renal perfusion pressure 1, 3
• Strictly avoid nephrotoxic agents perioperatively including NSAIDs, aminoglycosides, and excessive contrast 1, 3

Antihypertensive Medication Management

If the patient is on ACE inhibitors or ARBs, these should generally be continued perioperatively for renal protection, but held on the morning of surgery if there is concern for hemodynamic instability. 1, 2

• ACE inhibitors/ARBs provide critical renal protection in diabetic nephropathy and should be part of chronic management 1, 2
• However, in the setting of volume depletion or acute illness, temporarily hold ACE inhibitors/ARBs to prevent acute kidney injury and hyperkalemia 4
• Diuretics should be held on the morning of surgery to avoid exacerbating volume depletion 4
• Beta-blockers can generally be continued but may mask hypoglycemic symptoms during insulin therapy 4

Antidiabetic Medication Adjustments

Non-Insulin Medications

• Metformin should be discontinued from the evening before surgery (not just the morning of surgery) due to risk of lactic acidosis, particularly given impaired renal function 1
• All other non-insulin antidiabetic drugs (sulfonylureas, glinides, DPP-4 inhibitors, GLP-1 agonists) should be held on the morning of surgery 1
• If patient is on SGLT2 inhibitors, these should be discontinued at least 3 days before elective surgery due to risk of ketoacidosis, volume depletion, and acute kidney injury 5

Insulin Management

• Basal insulin should NEVER be stopped in Type 1 diabetes due to risk of ketoacidosis within hours 1
• Inject usual dose of basal insulin the evening before surgery 1
• If patient uses insulin pump, maintain it until arrival in the surgical unit 1
• Preoperative glucose infusion is not necessary if patient is not receiving insulin 1

Gastroparesis Assessment

• Assess for symptoms of gastroparesis (early satiety, bloating, nausea, vomiting) as this creates risk of aspiration at induction 1
• If gastroparesis is present or suspected, plan for rapid sequence induction technique to minimize aspiration risk 1

Surgical Considerations for Uterine Fibroid

• The benign uterine myoma itself does not require specific preoperative medical management beyond standard surgical preparation
• However, the complexity of managing diabetes with microvascular complications takes precedence in risk stratification
• Ensure adequate hemodynamic monitoring during surgery given the cardiovascular and renal risks outlined above 1, 3

Critical Pitfalls to Avoid

• Never assume absence of cardiac disease based on lack of symptoms—silent myocardial ischemia occurs in 30-50% of Type 2 diabetics 1
• Never overlook CAN screening when retinopathy is present—these microangiopathic complications cluster together and CAN dramatically increases perioperative risk 1
• Never allow mean arterial pressure to drop below 60 mmHg intraoperatively, as this critically compromises renal perfusion in patients with DCKD 1, 3
• Never stop basal insulin in Type 1 diabetes—ketoacidosis can develop within hours 1
• Never continue metformin through surgery in patients with renal impairment—hold from evening before due to lactic acidosis risk 1