The effects of morphine on venous tone in patients with acute pulmonary edema

In order to compare the venodilation effect of morphine in normal individuals (22) with that in patients (13) with heart failure morphine sulfate (0.1 mg/kg) was administered to 13 patients with mild pulmonary edema. After morphine congestive symptoms improved and venodilation was induced as determined by two independent techniques: venous pressure fell 10.2 mm Hg by the isolated hand technique and the venous volume of the forearm increased by 0.48 cc/100 ml, measured by equilibration technique. Neither finding differed from those in normal individuals. Reflex venoconstriction noted on the taking of a single deep breath was unaffected by morphine administration and was similar to that observed in normal subjects. Since the drug morphine sulfate does not cause a major pooling of blood in the limbs, the favorable effect of narcotics in patients with pulmonary edema must be caused by other mechanisms such as splanchnic pooling, afterload reduction or reduced breathing effort.