Dalhousie dyspnea scales: Pictorial scales to measure dyspnea during induced bronchoconstriction.

The aim of this study was to validate our Dalhousie Dyspnea Scales in children referred for histamine bronchoprovocation challenge. Seventy-four children rated their dyspnea after each FEV(1) measurement following inhalation of doubling histamine concentrations from 0.125 to 8.0 mg/ml by the standard tidal breathing method. Serial FEV(1) and dyspnea rating using the Dalhousie Dyspnea Scales were recorded and Kendall's tau was computed for dyspnea rating versus fall in FEV(1). Subjects were split into those with positive (DeltaFEV(1) >or= 20% with PC(20)