Intraoperative Insulin Infusion Rate Calculator
Calculate intravenous insulin titration for surgical patients
Understanding Intraoperative Insulin Infusion
Managing blood glucose (BG) levels during surgery is a critical component of perioperative care. Hyperglycemia in the operating room is associated with increased risks of surgical site infections, poor wound healing, and adverse cardiovascular events. The Insulin Infusion Rate Intraop Calculator helps anesthesia providers and surgical teams determine the appropriate dosage of intravenous regular insulin based on dynamic glucose measurements.
The Portland Protocol Logic
Many intraoperative insulin protocols are derived from the "Portland Protocol," which uses a dynamic multiplier to adjust for insulin resistance. The basic mathematical logic applied in this calculator is:
Insulin Rate (Units/hr) = (Current BG – 60) × Multiplier
The "60" represents a safety buffer to prevent hypoglycemia, and the multiplier is adjusted based on the patient's sensitivity. Common starting multipliers range from 0.01 to 0.02, but may be increased for patients with significant insulin resistance or high BMI.
Example Calculation
If a patient presents with an intraoperative blood glucose of 240 mg/dL and the protocol dictates a multiplier of 0.02:
- Current BG (240) – 60 = 180
- 180 × 0.02 = 3.6 Units/hr
Clinical Target Ranges
While target ranges vary by institution and surgery type, the following guidelines are commonly observed:
- General Surgery: 140–180 mg/dL is widely accepted to balance infection risk with hypoglycemia avoidance.
- Cardiac Surgery: Often more stringent, sometimes targeting 110–150 mg/dL.
- Critical Care: Avoiding values >180 mg/dL is the primary goal for most surgical patients.
Frequency of Monitoring
When an insulin infusion is active intraoperatively, blood glucose should be monitored at least every 60 minutes. If the rate of change is rapid (e.g., dropping more than 50 mg/dL per hour), monitoring frequency should increase to every 30 minutes to ensure the patient does not dip into a hypoglycemic state.