Response to Letter.

We would like to thank M. Korppi for his correspondence regarding our article. In the prospective, randomized, double-blind, controlled study, we enrolled 39 infants suffering from bronchiolitis, therefore analyzing the effect of 7% hypertonic saline—0.1% hyaluronic acid (7% HS– HA) on the clinical course of the disease. We agreewithM.Korppi that the evidence of the length of hospital stay (LOS) reduction was only indirect but it was supported (P1⁄4 0.04) and it implies a mean 0.7 day decrease in the study group (LOS reduction by 14.6%). This reduction is likely to bring about the clinical benefit of a possible reduction in economic expenses for bronchiolitis. On the other hand, no difference was observed between the two groups for the clinical score reduction over the first 3 days of hospitalization, as discussed by M. Korppi. In line with the literature suggesting that this therapy remains controversial, we did not mean to conclude that the hypertonic therapy works under any circumstances. According to our study, 7% HS–HA proved a safe treatment with similar percentages of cough after inhalation. Upon this result, whether using higher or multiple doses daily would safely and effectively improve clinical outcomes in infants suffering from bronchiolitis remains to be investigated. We totally agree with M. Korppi that now is the time to reach an agreement in the definition of bronchiolitis, as the first episode of acute lower airways infection, characterized by acute onset of respiratory distress with cough, tachypnea, retraction and diffuse crackles on auscultation in infants less than 12 months, or even 6 months of age. The definition of bronchiolitis as the first episode of acute viral wheeze occurring in infants less than 2 years, likely overlaps the early presentation of asthma. A single definition of bronchiolitis will allow researchers to analyze homogeneous RCTs. As discussed in our study, when used as hypertonic therapy, normal saline cannot therefore be considered an absolute placebo, as the positive effect on rehydrating the ‘airway surface liquid with 0.9 saline, might influence the clinical course in the control group. We agree with the Author that inhalation of physiologic saline constitutes an intervention, but the choice to give everyone an inhalation wasdictatedby the fact that the studywasdesigned in blind. Finally, we agree withM. Korppi that the only effective treatments in infants with bronchiolitis are close monitoring of oxygen saturation and fluid intake. By the way, the suggestion of high-flow nasal oxygen administration seems to be promising. In conclusion, we think it is time to reach an agreement on bronchiolitis definition, with the aim of evaluating new therapeutic strategies, particularly high-flow nasal oxygen administration, through comparison with supportive therapy only.