Ventilatory and pulmonary hemodynamic response to the respiratory stimulant doxapram in chronic bronchitis

When administered intravenously to patients suffering from chronic bronchitis the analeptic drug doxapram increases ventilation, PaO 2 and arterial pH, while arterial PaCO 2 decreases. The effects of doxapram on ventilation and on mean pulmonary arterial pressure ( P AP) were investigated during cardiac catheterization for diagnostic purposes in a group of 9 patients with chronic obstructive lung disease (COLD). The correlation between the pattern of pulmonary pressure and the behaviour of ventilation was considered. During rapid infusion (7 min) of the drug ventilation increased, and a highly significant increase in P AP was noted — the greater the increase in airway resistance, the greater the rise in P AP. These results suggest that in COLD patients undergoing oxygen therapy, doxapram must be administered in such a dose as to avoid the depressive effect of oxygen on the respiratory centre, without causing hyperventilation.