Overview
Definition:
Perioperative glycemic control refers to the management of blood glucose levels in patients before, during, and after surgical procedures
It involves maintaining glucose within a target range to minimize surgical site infections, reduce hospital stays, and improve overall patient outcomes.
Epidemiology:
Diabetes mellitus is prevalent in a significant proportion of surgical patients, estimated to be 20-30% in some surgical populations
Poor glycemic control is associated with increased morbidity and mortality in these patients.
Clinical Significance:
Maintaining optimal blood glucose levels perioperatively is crucial for wound healing, immune function, and reducing the risk of complications such as infection, organ dysfunction, and prolonged recovery
Uncontrolled hyperglycemia can impair neutrophil function and increase susceptibility to infections, while hypoglycemia can lead to neurological injury and cardiac events.
Indications For Glycemic Control
Patients With Diabetes:
All patients with pre-existing diabetes mellitus (Type 1 or Type 2) undergoing surgery.
Patients With Stress Hyperglycemia:
Patients without known diabetes who develop hyperglycemia due to surgical stress, critical illness, or medication use (e.g., corticosteroids).
Specific Surgical Procedures:
Cardiac surgery, neurosurgery, major abdominal surgery, and procedures in critically ill patients often require closer glycemic monitoring and management.
Preoperative Preparation
Assessment:
Thorough assessment of glycemic status, including HbA1c, fasting blood glucose, and history of diabetic complications
Review of current antidiabetic medications and insulin regimens.
Medication Adjustment:
Oral hypoglycemic agents are usually discontinued 24-48 hours before surgery
For patients on insulin, a basal-bolus regimen or continuous subcutaneous insulin infusion (CSII) may be continued or adjusted
Metformin is typically held due to the risk of lactic acidosis.
Patient Education:
Educating patients about fasting guidelines, medication adjustments, and the importance of glycemic control during the perioperative period.
Intraoperative Management
Monitoring:
Frequent blood glucose monitoring (e.g., every 1-2 hours) is essential
Arterial blood gas analysis can also provide glucose measurements in critically ill patients.
Target Glucose Range:
The generally accepted target range for blood glucose is 140-180 mg/dL (7.8-10 mmol/L) in most surgical patients
Some guidelines suggest an upper limit of 180 mg/dL.
Insulin Therapy:
Intravenous insulin infusion is the preferred method for managing hyperglycemia during surgery
A starting infusion rate of 1-2 units/hour is common, adjusted based on glucose trends
The standard insulin infusion protocol involves a continuous infusion of regular insulin, with adjustments based on hourly glucose measurements.
Hypoglycemia Management:
Prompt recognition and treatment of hypoglycemia (<70 mg/dL or <3.9 mmol/L) with intravenous dextrose is critical.
Postoperative Care
Continued Monitoring:
Postoperative glycemic monitoring should continue regularly, with frequency depending on the patient's condition and surgical procedure
Typically, monitoring continues until stable oral intake is established and glycemic control is achieved.
Insulin Therapy Transition:
Transitioning from intravenous insulin infusion back to subcutaneous insulin therapy
This requires careful timing and consideration of the insulin's pharmacokinetics and patient's oral intake.
Nutritional Support:
Ensuring adequate nutritional support, as appropriate, to aid recovery and improve glycemic stability
Enteral or parenteral nutrition may be required.
Complications Of Poor Glycemic Control
Surgical Site Infections:
Increased risk of wound infection and dehiscence due to impaired immune function and impaired collagen synthesis.
Organ Dysfunction:
Increased risk of myocardial infarction, stroke, acute kidney injury, and respiratory failure.
Delayed Healing:
Impaired wound healing and prolonged recovery times.
Neurological Deficits:
Risk of hypoglycemia-induced neurological damage or complications from hyperglycemia-related metabolic derangements.
Key Points
Exam Focus:
Understand the target glucose range (140-180 mg/dL) and the primary modality of intraoperative glycemic management (IV insulin infusion)
Know the common oral hypoglycemic agents and insulins typically held preoperatively.
Clinical Pearls:
Individualize glycemic targets based on patient comorbidities and surgical risk
A gradual reduction in blood glucose is often preferred to avoid hypoglycemia
Close collaboration between surgeons, endocrinologists, and anesthetists is vital.
Common Mistakes:
Over-reliance on sliding scale insulin postoperatively without a basal-bolus regimen
Failing to adjust insulin regimens promptly with changes in oral intake or clinical status
Not recognizing and managing hypoglycemia aggressively.