1. What is Predicted Body Weight?

Predicted Body Weight (PBW) is an estimate of ideal body weight based on height and gender. It's commonly used in critical care settings for ventilator tidal volume settings and medication dosing.

2. How Does the Calculator Work?

The calculator uses the standard PBW equations:

Where:

• \( height_{cm} \) — Height in centimeters
• 50 kg — Base weight for men
• 45.5 kg — Base weight for women
• 0.91 — Adjustment factor per cm above 5 feet (152.4 cm)

Explanation: The equations estimate ideal weight based on the assumption that the first 152.4 cm (5 feet) of height accounts for the base weight, with each additional cm adding 0.91 kg.

3. Importance of PBW Calculation

Details: PBW is crucial for setting appropriate tidal volumes in mechanical ventilation (typically 6-8 mL/kg PBW) and for dosing certain medications that should be based on ideal rather than actual body weight.

4. Using the Calculator

Tips: Enter height in centimeters and select gender. Height must be a positive value. The calculator will provide PBW in kilograms.

5. Frequently Asked Questions (FAQ)

Q1: Why use PBW instead of actual body weight?
A: PBW estimates lean body mass, which is more physiologically relevant for ventilation and drug distribution than total body weight, especially in obese patients.

Q2: How accurate is PBW?
A: PBW provides a reasonable estimate for most adults but may be less accurate in very short or tall individuals or those with unusual body proportions.

Q3: Should PBW be used for all medication dosing?
A: No, only for medications specifically dosed by ideal body weight. Many drugs are dosed by actual, adjusted, or other weight metrics.

Q4: What about pediatric patients?
A: Different equations are used for children. This calculator is for adults only.

Q5: How does PBW relate to BMI?
A: PBW approximates the weight that would give a BMI of about 22 kg/m² for men and 21 kg/m² for women.