Filling Pressures of the Heart and Pulmonary Circulation of the Patient with Coronary-artery Disease after Large Intravenous Doses of Morphine

Filling pressures of the heart and hemodynamic responses were studied before, during, and after administration of morphine, 2 mg/kg, intravenously (5 mg per minute) in eight patients with coronary-artery disease and normal ventricular contractility requiring myocardial revascularization. Left-heart filling pressure (LHFP) was estimated by measuring balloon-occluded pulmonary arterial pressure via a Swan-Ganz catheter, and right-heart filling pressure (RHFP) by right atrial pressure measurements. LHFP and RHFP were unchanged until 1.5 mg/kg morphine had been administered; after 2 mg/kg, LHFP had risen from a control level of 6.9 plus or minus 0.8 to 10.6 plus or minus 1.1 mm Hg (P less than .01) and RHFP from 2.9 plus or minus 0.4 to 4.9 plus or minus 0.8 mm Hg (P less than .05). Heart rate (P less than .02) and rate-pressure product (P less than .05), an indirect index of myocardial oxygen consumption, decreased throughout the study period. Systemic arterial pressure, cardiac index, and left ventricular stroke work decreased significantly only at the 0.5 mg/kg dose level, while systemic vascular resistance and stroke index remained unchanged. Mean pulmonary arterial pressure increased (P less than .05) after 1.5 mg/kg morphine, but pulmonary vascular resistance was unchanged. PaC02, pH, base excess, and hematocrit were constant throughout the study period. These data indicate that doses of morphine to 2 mg/kg, iv, are well tolerated by, and, presumably, decrease the myocardial oxygen consumption of, patients with coronary-artery disease. The hemodynamic response resembles that seen in man without hear or lung disease.