Which tidal-volume value aligns with lung-protective ventilation for obesity-related ventilation?

• A. 8 mL/kg of actual body weight
• B. 6 mL/kg of ideal body weight
• C. 10 mL/kg of actual body weight
• D. 12 mL/kg of ideal body weight

Answer: (B)

Lower tidal volumes are used to prevent lung overdistension and injury during ventilation, typically about 6 mL per kilogram of predicted (ideal) body weight. In obesity, the size of the lungs relates more closely to height than to total weight, so using actual body weight to set the volume can overestimate the lung capacity and raise airway pressures. Basing the tidal volume on ideal/predicted body weight keeps the delivered volume aligned with the patient’s lung size, reducing the risk of volutrauma. A practical safety target is to keep plateau pressures under 30 cm H2O while delivering this smaller tidal volume. Therefore, the tidal-volume value that aligns with lung-protective ventilation for obesity-related ventilation is 6 mL per kilogram of ideal body weight. Higher volumes, whether tied to actual weight or larger ideal-weight estimates, increase the risk of lung injury.