Second, in this study, neither of the NLFO treatments reached the recommended levels of temperature and humidity (100% relative humidity and 44 mg/L absolute humidity [AH]). Humidified NLFO obtained higher AH (21 mg/L) compared with dry nasal NLFO (9 mg/L). The optimal conditions of AH and relative humidity help to keep stable the rheological characteristics and volume of airway secretions, increase the mucociliary clearance, and prevent the inflammatory reactions to thermal injury or fluid imbalance. The heated humidification during NLFO provides a better temperature and humidity of inspired gas, preserving the MCC and pulmonary function. The authors declared that the evaluation of the clinical impact of heated humidification during NLFO was beyond the scope of this study. This choice may be questionable. We think that the inclusion of a third group with heated humidified NLFO would have added more value to this study, since it has considerable effects on the considered end points.