Hemodialysis Kt/V Calculator

Daugirdas Formula:

\[ Kt/V = -\ln(R - 0.008 \times t) + (4 - 3.5 \times R) \times UF / W \]

Post/Pre BUN Ratio (R):

(unitless)

Time (t):

hours

Ultrafiltration (UF):

liters

Weight (W):

Kt/V:

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1. What is the Daugirdas Formula?

The Daugirdas formula calculates Kt/V, a measure of dialysis adequacy that represents the fractional clearance of urea. It accounts for both dialysis dose and patient size to assess the effectiveness of hemodialysis treatment.

2. How Does the Calculator Work?

The calculator uses the Daugirdas formula:

\[ Kt/V = -\ln(R - 0.008 \times t) + (4 - 3.5 \times R) \times UF / W \]

Where:

\( R \) — Post-dialysis to pre-dialysis BUN ratio
\( t \) — Dialysis treatment time in hours
\( UF \) — Ultrafiltration volume in liters
\( W \) — Post-dialysis weight in kilograms

Explanation: The formula estimates dialysis adequacy by considering urea reduction, treatment duration, fluid removal, and patient size.

3. Importance of Kt/V Calculation

Details: Kt/V is a crucial parameter for assessing dialysis adequacy. Adequate Kt/V values (typically ≥1.2-1.4) are associated with better patient outcomes, reduced mortality, and improved quality of life for dialysis patients.

4. Using the Calculator

Tips: Enter the post/pre BUN ratio, dialysis time in hours, ultrafiltration volume in liters, and post-dialysis weight in kilograms. All values must be valid and positive.

5. Frequently Asked Questions (FAQ)

Q1: What is the target Kt/V value for hemodialysis?
A: The recommended target is typically 1.2-1.4 per session, though individual targets may vary based on patient characteristics and clinical guidelines.

Q2: Why is ultrafiltration included in the calculation?
A: Ultrafiltration accounts for convective urea removal during fluid removal, which contributes to overall dialysis adequacy.

Q3: When should BUN measurements be taken?
A: Pre-dialysis BUN should be measured before starting treatment, and post-dialysis BUN should be drawn 2-5 minutes after dialysis ends to avoid rebound effects.

Q4: Are there limitations to this formula?
A: The formula may be less accurate in patients with significant residual renal function, rapid urea rebound, or unusual volume distributions.

Q5: How often should Kt/V be measured?
A: Monthly measurement is typically recommended to ensure adequate dialysis delivery and make necessary treatment adjustments.