In ARDS, what tidal volume per kilogram of predicted body weight is recommended to minimize ventilator-induced lung injury?

• A. 4 mL/kg PBW
• B. 6 mL/kg PBW
• C. 8 mL/kg PBW
• D. 10 mL/kg PBW

Answer: (B)

Protective lung ventilation relies on using a lower tidal volume based on predicted body weight to prevent volutrauma in ARDS. The lungs in ARDS are inhomogeneous and easily overdistended, so delivering about 6 mL per kilogram of predicted body weight limits alveolar stretch while still providing adequate gas exchange. Using predicted body weight, rather than actual weight, ensures the tidal volume is scaled to lung size, which helps prevent overdistention across different patients. If tidal volumes were too high, the risk of ventilator-induced lung injury increases due to volutrauma; if they are too low, gas exchange can be insufficient and may cause unacceptable hypercapnia, though permissive hypercapnia can be tolerated with other supportive measures. In practice, this 6 mL/kg PBW target is paired with careful monitoring of plateau pressures (aiming for ≤30 cm H2O) and appropriate PEEP to optimize oxygenation.