When ventilating bariatric patients, which tidal-volume guideline is recommended?

• A. Vt for ideal body weight (not actual)
• B. Vt based on actual body weight
• C. Vt of 12 mL/kg
• D. No PEEP

Answer: (A)

In bariatric patients, tidal volume is chosen from ideal (predicted) body weight rather than actual weight because lung size correlates with height, not total body mass. Using ideal body weight keeps volumes in the lung-protective range (about 6 mL/kg predicted body weight, with adjustments to 4–8 mL/kg as clinically indicated). If you base Vt on actual weight, the tidal volume can become too large for the lungs, increasing the risk of volutrauma. A tidal volume of 12 mL/kg is therefore not appropriate. PEEP is a separate ventilator setting and not a tidal-volume guideline, so opting for no PEEP would also not align with best practice in many bariatric patients.