Effects of induced metabolic alkalosis on perception of dyspnea during flow-resistive loading

Treatment of dyspnea in patients with advanced cancer is an important issue. The purpose of the present study was to assess the effect of induced-metabolic alkalosis produced by administration of sodium bicarbonate on dyspneic sensation. In seven healthy subjects, dyspnea was induced by having them breathe with a flow-resistive load (24 cm H2O/L/sec) for 6 min before and after administration of sodium bicarbonate (0.5 mmol/kg, per os+2 mmol/kg, IV). The intensity of dyspnea was rated using a visual analogue scale (VAS). The VAS scores and minute ventilation during loaded breathing after administration of sodium bicarbonate were significantly lower than those before administration of sodium bicarbonate. These results indicate that induced metabolic alkalosis may alleviate the intensity of dyspneic sensation by a reduction in ventilatory drive.