Effect of prehydration on nasal mucociliary clearance in low relative humidity
Oozawa H, Kimura H, Noda T, Hamada K, Morimoto T, Majima Y
Auris Nasus Larynx 2012; 39: 48-52
The nasal mucociliary clearance in the upper respiratory tract has been reported to be impaired in a low relative humidity environment. We studied the influence of ingesting an ion supply drink on the nasal mucociliary clearance in a low relative humidity environment.
Fourteen healthy male subjects were studied in three randomized cross-over intervention trials using an ion supply drink, water and a control condition with no prehydration. After resting in a normal room for 20 min at a temperature 23℃ and a relative humidity of 50%, the nasal mucociliary clearance was evaluated by the saccharin granule technique*. After the baseline measurement, the subjects moved to an environmental chamber maintained at a temperature 23℃ and a relative humidity of 10%, and drank each test beverage at a volume of 6 ml/kg body weight. After entering the environmental chamber they rested in a sitting position until the end of the experiment, and the saccharin granule technique was used two and four hours after entering the chamber. * A evaluation method for the nasal mucociliary transport function as transit time between placing the saccharin on the nasal septal mucosa and the moment when the subject could perceive the taste of sweetness.
In the no fluid (control) trial, a decline in the nasal mucociliary clearance was observed after the subjects entered the environmental chamber. In contrast, a significant suppression of this decline in the nasal mucociliary clearance was observed in the ion supply drink trial. On the other hand, no difference was observed in the water trial.
Adequate hydration using the ion supply drink helped to maintain the nasal mucociliary clearance, which is one of the physical defense systems that are compromised under low relative humidity conditions.