Hemodialysis UFR Calculator
Include prime, rinseback, and oral intake during session.
Total Volume to Remove:
0 mL
Hourly UFR:
0 mL/hr
Normalized UFR (Safety Metric):
0 mL/kg/hr
About Ultrafiltration Rate (UFR) Calculation
In hemodialysis, the Ultrafiltration Rate (UFR) measures the speed at which fluid is removed from the patient's blood. Accurate calculation of UFR is critical for patient safety, as removing fluid too quickly can lead to intradialytic hypotension, myocardial stunning, and muscle cramps.
How to Calculate UFR
The calculation involves determining the total fluid volume that needs to be removed to reach the patient's "dry weight" (the target post-dialysis weight) within the prescribed treatment time. The formula typically accounts for the weight gained between sessions plus any additional fluids administered during the treatment (such as rinseback or oral intake).
Formula:
Total Volume (mL) = (Pre-Weight – Dry Weight) * 1000 + Additional Fluid
UFR (mL/hr) = Total Volume / Treatment Hours
Normalized UFR (mL/kg/hr) = UFR (mL/hr) / Dry Weight (kg)
Total Volume (mL) = (Pre-Weight – Dry Weight) * 1000 + Additional Fluid
UFR (mL/hr) = Total Volume / Treatment Hours
Normalized UFR (mL/kg/hr) = UFR (mL/hr) / Dry Weight (kg)
Clinical Safety Limits (mL/kg/hr)
Modern nephrology guidelines emphasize the Normalized UFR, which adjusts the rate based on the patient's body size. A specific threshold is often monitored to reduce mortality risk:
- Safe Zone (< 10 mL/kg/hr): Generally considered safe and associated with better long-term survival rates.
- Caution Zone (10 – 13 mL/kg/hr): Requires careful monitoring. Higher risk of hypotension compared to lower rates.
- High Risk (> 13 mL/kg/hr): Strongly associated with increased cardiovascular mortality and hospitalization. It is often recommended to extend treatment time or increase frequency if the required rate exceeds this limit.
Input Definitions
- Pre-Dialysis Weight: The patient's weight measured immediately before starting the dialysis session.
- Target Dry Weight: The physician-prescribed goal weight representing the patient's weight without excess fluid.
- Additional Fluid: Volume of fluid added to the patient during the process (saline prime, rinseback) or consumed orally, which must also be removed.
- Treatment Duration: The prescribed length of the dialysis session in hours.