ventilation
IBW (male) = 50 + 2.3 × (Height in inches − 60)
Normal: Variable by height
Normal: Patient-specific
Ideal body weight estimates the weight corresponding to a healthy BMI for a given height. In mechanical ventilation, IBW is critical because lung size is determined by height, not actual body weight. Using actual body weight to calculate tidal volume in obese patients would cause dangerously large tidal volumes and volutrauma.
Always used when calculating tidal volumes for mechanical ventilation (target 4–8 mL/kg IBW, with 6 mL/kg IBW as the ARDSNet lung-protective target). NEVER use actual body weight for ventilator tidal volume calculations.
5'10" male (70 inches)
→ 73 kg
TV range: 292–584 mL (4–8 mL/kg); ARDS target 438 mL (6 mL/kg)
6'0" male (72 inches)
→ 77.6 kg
TV range: 310–620 mL; ARDS target 466 mL
An obese patient (actual weight 150 kg) may have an IBW of 80 kg — using actual weight would deliver nearly DOUBLE the appropriate tidal volume, causing dangerous lung overdistention. This is one of the most critical and most tested concepts in NBRC ventilator management.