EFFECT OF INHALATION OF HOT HUMIDIFIED AIR ON EXPERIMENTAL RHINOVIRUSINFECTION

Objective.-Nasal inhalation of steam has been proposed as treatment of viral colds on the assumption that increased intranasal temperature w ill inhibit replication of rhinovirus (RV). The effect of steam inhala tion on RV shedding by infected volunteers was examined in this study. Design.-Randomized controlled trial. Volunteers experimentally infect ed with RV were treated with machine-generated humidified air, which w as either hot (active) or at room temperature (placebo). Viral sheddin g was assessed over the 4 days following treatment. Setting.-Local hot el. Participants.-Twenty volunteers from the university community who were susceptible to the challenge virus. Intervention.-Two 30-minute i ntranasal treatments, the first at 24 hours after inoculation and the second at 48 hours. The temperature of active vapor was 42-degrees-C t o 44-degrees-C and of placebo vapor was 22-degrees-C. Main Outcome Mea sures.-Viral titers in nasal washings on each of 5 days following inoc ulation. Results.-Mean viral titers prior to the first treatment were 10(1.7) tissue culture infectious doses50 per milliliter in the active group and 10(1.5) in the placebo group. Mean titers for the next 4 da ys were 10(1.7), 10(1.7), 10(1.2), and 10(0.9)/mL in the active group and 10(1.8), 10(1.9), 10(1.6, and 10(0.7)/mL in the placebo group (no significant difference). The proportion of volunteers who shed virus o n each day was also similar in the two groups. Conclusion.-Two nasal i nhalation treatments with steam had no effect on viral shedding in vol unteers with experimental RV colds.