Inhibition of the bronchial response to respiratory heat exchange by increasing doses of terbutaline sulphate.

Ten asthmatic patients inhaled terbutaline sulphate (250, 500, or 1000 micrograms) or placebo on separate days, double blind and in random order, 30 minutes before isocapnic hyperventilation induced by cold air inhaled in doses that increased in a precisely controlled manner. The respiratory heat exchange (RHE) was calculated for each level of ventilation and the results were expressed as the RHE causing a fall in FEV1 of 10% (PD10RHE). The …