Hemodynamic effects of morphine and nalbuphine in acute myocardial infarction

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Abstract
Hemodynamic effects of morphine and the new narcotic analgesic, nalbuphine, were compared in a randomized, double-blind study in 15 patients with acute myocardial infarction (11 men and 4 women, average 56.2 yr) and normal group mean hemodynamic function. During a 1 h evaluation the hemodynamic effects were small but there were changes in several parameters. Morphine reduced heart rate (78 to 72 bpm [beats/min], P < 0.01) and diastolic and mean arterial pressures (69 to 64 mm Hg, P < 0.05; and 91 to 84 mm Hg, P < 0.05); nalbuphine was associated with a decrease in heart rate (82 to 72 bpm, P < 0.01), decrease in cardiac index, which remained within the normal range (3.16-2.75 l/min per m2, P < 0.01) and an increase in systemic vascular resistance (1204-1461 dynes .cntdot. s .cntdot. cm-5, P < 0.05). Neither drug altered systolic arterial pressure, pulmonary artery pressure, pulmonary capillary wedge pressure, stroke index, stroke work index or pulmonary vascular resistance. Echocardiographic assessment revealed diminution of left ventricular mean velocity of circumferential fiber shortening [circ] after nalbuphine (1.26 to 1.08 circ/s, P < 0.05). Both drugs induced small reductions in respiratory rate and arterial pH and increases in alveolar partial pressure of O2. There were no changes in arterial partial pressure of O2. Due to the absence of clinically important deleterious effects on cardiac pump function, nalbuphine merits further investigation as an analgesic in acute myocardial infarction.