What tidal volume is recommended to minimize ventilator-induced lung injury in adults on mechanical ventilation?

• A. 4 mL/kg predicted body weight
• B. 6 mL/kg predicted body weight
• C. 8 mL/kg predicted body weight
• D. 10 mL/kg predicted body weight

Answer: (B)

The main concept is lung-protective ventilation, which uses lower tidal volumes to prevent overdistension of the lung and reduce ventilator-induced injury. In adults on mechanical ventilation, the recommended target is about 6 mL of tidal volume per kilogram of predicted body weight. Using predicted body weight, calculated from height and sex, ensures the volume matches lung size rather than actual body weight, preventing both under- and over-ventilation.

This 6 mL/kg PBW target is supported by key trials showing better outcomes and lower mortality in patients requiring ventilation, especially with ARDS, when tidal volumes are limited and plateau pressures kept below roughly 30 cm H2O. It also allows for permissive hypercapnia if the pH remains acceptable, provided gas exchange is manageable. Higher tidal volumes (8–10 mL/kg) increase the risk of volutrauma and lung injury, while very low volumes (around 4 mL/kg) can lead to excessive CO2 retention and inadequate ventilation. So, 6 mL/kg predicted body weight strikes the best balance to minimize injury while ensuring adequate gas exchange.