Hemodynamic and respiratory effects of morphine and butorphanol

The hemodynamic effects of butorphanol, a potent synthetic narcotic-antagonist analgesic, were investigated and compared with those of morphine. A total of 20 patients were studied (8 butorphanol, 12 morphine) at the time of diagnostic cardiac catheterization. Butorphanol decreased pH, PCO2, and systemic artery pressure and increased PCO2, cardiac index, and pulmonary artery pressure. Morphine caused similar changes in pH, PO2, systemic artery pressure, and PCO2 but much smaller changes in cardiac index and no change in pulmonary artery pressure. The clinical implications and possible mechanisms are discussed.