Cyclic Tpn Rate Calculator

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Cyclic TPN Rate Calculator

Total bag volume prescribed.
Total time for infusion.
Time to reach goal rate (Taper Up).
Time to wean off (Taper Down).
Calculation Results
Main (Plateau) Rate: — mL/hr
Taper Rate (Up/Down): — mL/hr
Duration at Main Rate: — hours

Understanding Cyclic TPN Infusion

Total Parenteral Nutrition (TPN) is often administered in a continuous 24-hour cycle in hospital settings. However, for long-term home patients, Cyclic TPN is the preferred method. This involves infusing the total daily volume over a shorter period (usually 10 to 16 hours), typically at night, allowing the patient freedom from the pump during the day.

Why Use a Cyclic Rate?

Cycling TPN provides several physiological and psychological benefits:

  • Liver Health: Continuous infusion can lead to hepatosteatosis (fatty liver) and cholestasis due to constant high insulin levels. Cycling creates a fasting window that allows fat mobilization and prevents liver damage.
  • Quality of Life: Infusing primarily during sleep frees the patient for daily activities, work, or school.
  • Hormonal Balance: Mimics normal meal patterns, allowing insulin levels to drop and glucagon to rise during the off-cycle.
Safety Warning: Cyclic TPN requires "tapering" (ramping up and down) to prevent rapid fluctuations in blood glucose.
  • Ramp Up: Prevents hyperglycemia by allowing the pancreas time to increase insulin production.
  • Ramp Down: Prevents rebound hypoglycemia. If the infusion stops abruptly, high insulin levels can cause blood sugar to crash.

How the Formula Works

To calculate the infusion rates, we account for the volume infused during the taper periods (usually 1 hour up and 1 hour down at half the goal rate) and the volume infused during the plateau period.

The standard formula used in this calculator is:

Goal Rate = Total Volume / (Cycle Hours - 0.5 × (Ramp Up + Ramp Down))

For example, if infusing 2000mL over 12 hours with a 1-hour taper up and 1-hour taper down:

  • Effective Time = 12 – 0.5(1 + 1) = 11 hours.
  • Goal Rate = 2000 / 11 = 181.8 mL/hr.
  • Taper Rate = 181.8 / 2 = 90.9 mL/hr.

Clinical Considerations

While this calculator provides a mathematical guideline, specific patient protocols may vary. Some institutions use step-wise tapers (e.g., increasing rate every 30 minutes). Always verify the calculated pump settings against the physician's specific orders.

function calculateTPN() { // 1. Get Inputs var volume = document.getElementById("totalVolume").value; var totalTime = document.getElementById("cycleDuration").value; var rampUp = document.getElementById("rampUp").value; var rampDown = document.getElementById("rampDown").value; // 2. Convert to floats volume = parseFloat(volume); totalTime = parseFloat(totalTime); rampUp = parseFloat(rampUp); rampDown = parseFloat(rampDown); // 3. Validation if (isNaN(volume) || isNaN(totalTime) || isNaN(rampUp) || isNaN(rampDown)) { alert("Please enter valid numbers for all fields."); return; } if (volume <= 0 || totalTime = totalTime) { alert("Total cycle duration must be greater than the sum of Ramp Up and Ramp Down times."); return; } // 4. Calculation Logic // Formula: Rate = V / (T_total – 0.5 * (T_up + T_down)) // Assumption: Taper rate is 50% of the plateau rate. var effectiveHours = totalTime – 0.5 * (rampUp + rampDown); var plateauRate = volume / effectiveHours; var taperRate = plateauRate * 0.5; // Standard practice is half rate for tapers var plateauTime = totalTime – rampUp – rampDown; // 5. Display Results document.getElementById("resPlateauRate").innerHTML = plateauRate.toFixed(1) + " mL/hr"; document.getElementById("resTaperRate").innerHTML = taperRate.toFixed(1) + " mL/hr"; document.getElementById("resPlateauTime").innerHTML = plateauTime.toFixed(1) + " hours"; // 6. Generate Schedule Table var scheduleHTML = ''; // Ramp Up Row if (rampUp > 0) { var upVol = taperRate * rampUp; scheduleHTML += ''; } // Plateau Row var platVol = plateauRate * plateauTime; scheduleHTML += ''; // Ramp Down Row if (rampDown > 0) { var downVol = taperRate * rampDown; scheduleHTML += ''; } // Total Row var totalCalcVol = (rampUp > 0 ? taperRate * rampUp : 0) + (plateauRate * plateauTime) + (rampDown > 0 ? taperRate * rampDown : 0); scheduleHTML += ''; scheduleHTML += '
PhaseDurationRate SettingApprox. Vol
Ramp Up' + rampUp + ' hr' + taperRate.toFixed(1) + ' mL/hr' + upVol.toFixed(1) + ' mL
Main Rate' + plateauTime + ' hr' + plateauRate.toFixed(1) + ' mL/hr' + platVol.toFixed(1) + ' mL
Ramp Down' + rampDown + ' hr' + taperRate.toFixed(1) + ' mL/hr' + downVol.toFixed(1) + ' mL
Total' + totalTime + ' hr–' + totalCalcVol.toFixed(1) + ' mL
'; document.getElementById("scheduleOutput").innerHTML = scheduleHTML; // Show result section document.getElementById("result-section").style.display = "block"; }

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