Glucose Infusion Rate Tpn Calculation

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Glucose Infusion Rate (GIR) Calculator

Calculated GIR:

function calculateGIR() { var weight = parseFloat(document.getElementById("weight").value); var dextrose = parseFloat(document.getElementById("dextrose").value); var rate = parseFloat(document.getElementById("rate").value); var resultBox = document.getElementById("result-box"); var resultValue = document.getElementById("result-value"); var resultText = document.getElementById("result-text"); if (isNaN(weight) || isNaN(dextrose) || isNaN(rate) || weight <= 0) { alert("Please enter valid positive numbers. Weight must be greater than zero."); return; } // GIR Formula: (IV Rate mL/hr * % Dextrose) / (6 * Weight kg) // This is derived from: (mL/hr * mg/mL Dextrose) / (kg * 60 min/hr) var gir = (rate * dextrose) / (6 * weight); resultValue.innerHTML = gir.toFixed(2) + " mg/kg/min"; resultBox.style.display = "block"; if (gir 12) { resultText.innerText = "Current rate is high. Monitor for hyperglycemia and lipid synthesis issues."; } else { resultText.innerText = "GIR is within the typical physiological range for neonates."; } }

Understanding Glucose Infusion Rate (GIR) in TPN

Glucose Infusion Rate (GIR) is a critical metric used primarily in neonatal intensive care units (NICU) and for patients receiving Total Parenteral Nutrition (TPN). It measures the amount of glucose a patient receives per kilogram of body weight per minute. Accurate GIR calculation is vital to prevent metabolic complications such as hypoglycemia or hyperglycemia.

The Importance of GIR Calculation

In pediatric and neonatal care, the liver's ability to store glycogen is limited. Patients rely on a steady supply of intravenous dextrose. The GIR helps clinicians titrate the concentration of dextrose and the rate of fluid administration to mimic the natural hepatic glucose production rate, which is typically between 4 to 8 mg/kg/min in newborns.

The Mathematical Formula

The standard formula used in clinical settings for GIR is:

GIR (mg/kg/min) = [Rate (mL/hr) × Dextrose %] / [6 × Weight (kg)]

Why the number 6? It is a conversion factor that simplifies the math. Since there are 1000mg in a gram, 60 minutes in an hour, and dextrose percentage is per 100mL, the math (1000 / 60 / 100) reduces to 1/6.

Practical Example

Imagine a neonate weighing 2.5 kg. They are receiving an IV of D12.5% (12.5% dextrose) at a rate of 6 mL/hr. To find the GIR:

  • Multiply Rate (6) by Concentration (12.5) = 75
  • Multiply Weight (2.5) by 6 = 15
  • Divide the first result by the second: 75 / 15 = 5.0 mg/kg/min

In this example, a GIR of 5.0 is within the standard starting range for most stable neonates.

Clinical Reference Ranges

Category GIR Range (mg/kg/min)
Starting range (Neonates) 4 – 6 mg/kg/min
Maintenance (Stable) 6 – 8 mg/kg/min
Maximum Threshold 12 – 14 mg/kg/min

Monitoring and Adjustments

When adjusting TPN, it is recommended to increase or decrease the GIR gradually (usually by 1-2 mg/kg/min per day) while monitoring blood glucose levels. High GIR values can lead to steatosis (fatty liver) and excessive CO2 production, making it harder for ventilated patients to be weaned off respiratory support.

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