The Effect of Bendrofluazide and Frusemide on the Ventilatory Response to Carbon Dioxide and Hypoxia in Normal Man

Abstract

1. We have determined the ventilatory response to CO₂ at two levels of end-tidal O₂ tension in eight normal subjects before and after (1) 4 days of 0.242 mmol (80 mg) oral frusemide daily and (2) 4 days of 0.024 mmol (10 mg) bendrofluazide daily. 2. Frusemide produced no significant alkalosis, change in end-tidal CO₂ tension or alteration in the CO₂ response line. However, we did demonstrate a linear relationship between the change in plasma total CO₂ content and the change in intercept of the CO₂ response line in hyperoxia after frusemide. 3. Bendrofluazide produced a metabolic alkalosis with no significant change in end-tidal CO₂ tension. The CO₂ response line after the drug showed a decrease in slope in hyperoxia and a shift to the right of the intercept in hypoxia. There was no relationship between change in plasma total CO₂ content and change in the intercept of the CO₂ response line in hyperoxia. 4. If these results obtained on normal subjects are applicable to patients with chronic bronchitis and emphysema, frusemide might be the diuretic of choice for use with controlled oxygen therapy in the management of acute exacerbations of this disease when it is complicated by ventilatory failure.