What is a recommended insulin (intravenous insulin) gtt (glucose titration) protocol for patients post Coronary Artery Bypass Graft (CABG)?

Insulin GTT Protocol for Post-CABG Patients

Continuous intravenous insulin should be used to maintain blood glucose levels less than or equal to 180 mg/dL while avoiding hypoglycemia in post-CABG patients to reduce adverse events, including deep sternal wound infection. 1

Initial Management

• Implement continuous intravenous insulin therapy immediately post-CABG to achieve and maintain blood glucose concentration ≤180 mg/dL 1
• Monitor blood glucose levels every 1-2 hours while the patient is NPO to detect hypoglycemia or hyperglycemia 2
• Target blood glucose range should be 100-180 mg/dL (5.6-10.0 mmol/L) during the perioperative period 2
• Avoid targeting blood glucose <140 mg/dL as this has uncertain effectiveness and may increase risk of hypoglycemia 1

Insulin Infusion Protocol

• Start with a fixed rate insulin infusion of 0.1 IU/kg/h and adjust based on blood glucose measurements 3
• Adjust the infusion rate of glucose (30%) to maintain blood glucose levels within target range 3
• For patients with severe hyperglycemia (>300 mg/dL or 16.5 mmol/L), check for ketosis and ensure adequate hydration 1

Transition from IV to SC Insulin

• Maintain IV insulin until blood glucose levels stabilize at ≤180 mg/dL (10 mmol/L) and oral feeding resumes 1
• Transition to subcutaneous insulin when blood glucose levels have been stable for at least 24 hours and IV insulin infusion rate is <3 U/h 1, 4
• Early transition (postoperative day 1) from IV to SC insulin is associated with shorter ICU and hospital length of stay without increasing the risk of transitioning back to IV insulin 4

Subcutaneous Insulin Regimen

• For transition protocol, administer long-acting (basal) insulin immediately after stopping IV insulin 1
• Calculate initial SC insulin dose based on total daily IV insulin requirements 1
• Half of the total dose of IV insulin corresponds to the dose of slow-acting insulin, the other half to doses of ultra-rapid analogue 1
• For patients not previously on insulin with IV infusion <24 hours, start insulin at 0.5-1 IU/kg depending on weight (half slow insulin, half ultra-rapid analogue) 1
• Make the injection of ultra-rapid analogue at the first meal, adapting it to the quantity of carbohydrates ingested 1

Management of Glycemic Emergencies

• For hypoglycemia (<3.3 mmol/L or 60 mg/dL), administer glucose immediately even in the absence of clinical signs 1
• Use oral glucose if patient is conscious, and IV glucose if patient is unconscious or unable to swallow 1
• For blood glucose between 3.8-5.5 mmol/L (70-100 mg/dL) with symptoms of hypoglycemia, administer glucose 1
• For severe hyperglycemia (>16.5 mmol/L or 300 mg/dL), administer ultra-rapid insulin and ensure adequate hydration 1

Special Considerations

• For patients with personal insulin pumps, reconnect the pump as soon as the patient can manage autonomously 1
• If the patient is not autonomous, initiate a basal-bolus scheme by immediate SC injection of insulin 1
• Non-diabetic patients may benefit more from intensive insulin therapy (100-140 mg/dL) than patients with diabetes 5
• Consider using a modified glucose-insulin-potassium (GIK) solution for diabetic CABG patients, which has been shown to improve perioperative outcomes 6

Monitoring Recommendations

• Regular blood glucose monitoring is essential due to the high risk of glycemic fluctuations 2
• Continue monitoring blood sugar levels postoperatively to detect hyperglycemia or hypoglycemia 1
• Adjust insulin doses based on blood glucose patterns, carbohydrate intake, and activity levels 2