Over 2 decades ago, a series of in vitro and in vivo studies compared aerosol delivery using dry gas versus heated humidified gas during invasive mechanical ventilation.1,-,5 These studies found that aerosol delivery efficiency was greater with dry gas than with heated humidified gas,1,-,5 likely due to the increased diameter of aerosol particles caused by absorbing water vapor from the heated humidification. As a result, some clinicians and researchers have recommended turning off humidifiers during nebulization, particularly to optimize the delivery of aerosolized antibiotics for mechanically ventilated patients.6 In clinical practice, 8–37% clinicians have reported turning off humidifiers during aerosol delivery for mechanically ventilated patients.7,-,9 However, concerns have been raised regarding the potential harms of turning off humidification.

In this issue, Lellouche et al10 critically evaluated the hygrometry of dry gas, heated humidified gas, and the dynamic process of turning off humidifiers. They observed a rapid decrease in humidity …

Correspondence: Jie Li PhD RRT RRT-ACCS RRT-NPS FAARC FCCM, 600 S Paulina Street, Suite 765, Chicago 60612, IL. E-mail: jie_lirush.edu