Total volume goal for the dialysis session (UF Goal).
Length of the dialysis session.
The patient's target post-dialysis weight in kilograms.
Calculated Ultrafiltration Rate
0 mL/kg/hr
Total Fluid Removed
0 mL
How Do You Calculate Ultrafiltration Rate?
The Ultrafiltration Rate (UFR) is a critical metric in hemodialysis that measures the speed at which fluid is removed from a patient's blood relative to their body weight and the duration of the treatment. Managing UFR is essential for preventing complications such as intradialytic hypotension (low blood pressure), cramping, and myocardial stunning.
The UFR Formula
To calculate the Ultrafiltration Rate, you need three specific data points: the total volume of fluid to be removed (UF Goal), the duration of the treatment, and the patient's dry weight.
Note: If your fluid removal goal is in Liters, you must multiply by 1000 to convert it to Milliliters (mL) before dividing.
Step-by-Step Calculation Example
Let's look at a realistic clinical scenario:
Fluid Goal: 3.0 Liters (3000 mL)
Treatment Time: 4 Hours
Dry Weight: 70 kg
The calculation would be:
Convert Liters to mL: 3.0 L = 3000 mL.
Multiply Time by Weight: 4 hrs × 70 kg = 280.
Divide Volume by the result: 3000 / 280 = 10.71 mL/kg/hr.
Interpreting the Results
Current medical guidelines and studies suggest specific safety thresholds for UFR:
< 10 mL/kg/hr: Generally considered safe for most patients.
10 – 13 mL/kg/hr: Cautionary zone. Higher risk of hypotension and cardiovascular stress.
> 13 mL/kg/hr: High risk. Associated with increased mortality and myocardial stunning. Consider extending treatment time or reducing fluid gains between sessions.
Why is UFR Important?
Rapid fluid removal shifts fluid from the extravascular space to the intravascular space. If the rate of removal (ultrafiltration) exceeds the rate at which the body can refill the blood vessels (plasma refill rate), the patient's blood volume drops, leading to a drop in blood pressure. Keeping the UFR low preserves residual kidney function and protects the heart.
function calculateUFR() {
// Get input elements by ID
var volumeInput = document.getElementById('ufrTotalVolume');
var timeInput = document.getElementById('ufrDuration');
var weightInput = document.getElementById('ufrDryWeight');
var resultBox = document.getElementById('ufrResult');
var valueDisplay = document.getElementById('ufrValueDisplay');
var totalMlDisplay = document.getElementById('ufrTotalMlDisplay');
var statusMsg = document.getElementById('ufrStatusMsg');
// Parse values
var volumeLiters = parseFloat(volumeInput.value);
var timeHours = parseFloat(timeInput.value);
var dryWeight = parseFloat(weightInput.value);
// Validation: Ensure numbers are valid and positive
if (isNaN(volumeLiters) || volumeLiters < 0 ||
isNaN(timeHours) || timeHours <= 0 ||
isNaN(dryWeight) || dryWeight <= 0) {
alert("Please enter valid positive numbers for all fields.");
return;
}
// Calculation Logic
// 1. Convert Liters to Milliliters
var volumeMl = volumeLiters * 1000;
// 2. Calculate UFR: mL / (hours * kg)
var ufr = volumeMl / (timeHours * dryWeight);
// Round to 2 decimal places
var ufrFormatted = ufr.toFixed(2);
var totalMlFormatted = volumeMl.toFixed(0);
// Display Results
valueDisplay.innerHTML = ufrFormatted + " mL/kg/hr";
totalMlDisplay.innerHTML = totalMlFormatted + " mL";
resultBox.style.display = "block";
// Determine Status
statusMsg.className = "ufr-status"; // Reset classes
if (ufr < 10) {
statusMsg.innerHTML = "Result: Safe Range (= 10 && ufr 13 mL/kg/hr)";
statusMsg.classList.add("status-danger");
}
}