Reversibility tests in chronic obstructive airways disease: their predictive value with reference to benefit from domiciliary nebuliser therapy

The role of short-term tests of reversibility in selecting patients with COAD for long-term nebuliser therapy is uncertain. In a double-blind placebo-controlled crossover study we have examined the correlation between short-term reversibility and response to a home nebuliser. We studied 20 patients with severe COAD (mean age 66, mean FEV l 0·81 l) and little reversibility (< 20% increase in FEV l post-inhaled salbutamol 200 g and < 25% increase in peak expiratory flow rate, PEFR, on oral steroids). PEFR, spirometry, lung volumes and airways conductance were recorded before and 1 h after a mixture of nebulised ipratropium 0·5 mg and fenoterol 1·25mg. Patients then recorded twice-daily PEFR at home while they received neblised ipratropium plus fenoterol, or saline placebo, four times a day for three week blocks using a double-blind cross over protocol. Mean PEFR on home nebuliser rose from 164 1 m −1 (placebo) to 196 1 m −1 (ipratropium plus fenoterol), paired t-test P = 0·0001. Correlation coefficients between short-term response for PEFR, spirometry and lung volumes, and improvement in home PEFR on nebulised ipratropium plus fenoterol, were all poor ( R = −0·37–0·35, P = 0·83–0·11). We conclude that in severe COAD, reversibility tests of PEFR, spirometry and lung volumes do not correlate with response to a home nebuliser. Home measurements of PEFR are probably the best objective method of assessing response to a home nebuliser in such patients.