• Jorge Jorquera, Orlando Díaz, and Carmen Lisboa.
• Departmento de Enfermedades Respiratorias, Unidad de Cuidados Intensivos, Pontificia Universidad Catolica de Chile, Santiago, Chile. jjorquera@hotmail.com
• Rev Med Chil. 2003 Jun 1;131(6):605-12.

BackgroundThe six minute walk test (6 MW) elicits dynamic hyperinflation (DH) in severe COPD patients, which can be evaluated by reductions in inspiratory capacity (IC). Although IC is currently used to determine the effects of bronchodilators on DH during exercise tests on a cycle ergometer, its usefulness during a walking test has not been evaluated.AimTo study the acute effects of ipratropium bromide (IB) on forced expiratory volume at l second (FEV1) and IC at rest and on DH during exercise assessed by the 6 MW.Subjects And MethodsFifteen stable COPD patients were randomly allocated in a double-blind, placebo-controlled, crossover fashion to 2 treatment periods using a single dose of nebulized IB 500 mg or placebo. Spirometry, including IC, and 6 MW were measured at baseline and after IB and placebo. IC was also measured 15 min after exercise. Dyspnea, oxygen saturation (SpO2) and heart rate were assessed at the end of exercise.ResultsAfter IB, 8/15 patients exhibited a clinically significant increase in IC (> or = 10% predicted). A similar increase in FEV1 was observed in only one patient. No changes were observed with placebo. A significant increase in 6 MW from baseline (p = 0.007) was found after IB (45 +/- 14 m) compared to placebo (0.5 +/- 9 m), whereas dyspnea was significantly lower. Inspiratory capacity fell after 6 MW with both treatments, but it reached their baseline values at 15 min after exercise only with IB.ConclusionsOur results demonstrate that IC provides additional information to conventional spirometry on the acute effects of bronchodilators and confirm its value to assess DH during a walking test.

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