Nebulized isotonic saline: An active placebo in asthma?

The placebo effect is well documented with reports of up to 42% protection against exercise-induced bronchoconstriction. In the course of a study of inhaled heparin treatment, significant changes in sputum inflammation cell counts following inhaled saline were observed. Sputum analysis has been previously shown to be an excellent indicator of asthma treatment outcomes (Pizzichini et al., AJRCCM 1996). Stable asthmatics with sputum eosinophilia (>5% total cell count) were given a single dose of nebulized isotonic saline (8mL). Total and differential cell counts were monitored in induced sputum 24 hours pre- and 6 and 24 hours post-treatment. The first 3 patients showed a reduction in sputum eosinophilia by 52%, 86% and 100% from baseline making a crossover comparison with heparin impossible and necessitating a change in study design. Sputum eosinophilia remained suppressed (<4% TCC) for 7 days. The "placebo" effect of saline in this clinical situation may be of therapeutic significance.