Comparison of nalbuphine hydrochloride versus morphine sulfate for acute myocardial infarction with elevated pulmonary artery wedge pressure

The hemodynamic and respiratory effects of intravenous nalbuphine hydrochloride and morphine sulfate were compared in a randomized fashion in 20 patients (age 65 ± 11 years) with acute myocardial infarction and elevated pulmonary artery wedge pressure. Titration of the nalbuphine dose to lower pulmonary artery wedge pressure by ≥25% resulted in a decrease of this parameter from 22 ± 3 to 15 ± 4 mm Hg, and was associated with a reduction in heart rate from 106 ± 20 to 96 ± 19 beats/min (p < 0.05) and decreases in mean blood pressure (78 ± 8 to 70 ± 12 mm Hg, p < 0.05) and mean pulmonary artery pressure (31 ± 4 to 22 ± 5 mm Hg, p < 0.05), without any remarkable change seen in cardiac index (2.21 ± 0.43 to 2.22 ± 0.50 liter/min/m², difference not significant), stroke volume index (22 ± 7 to 23 ± 4 ml/m², difference not significant), stroke work index (17 ± 7 to 18 ± 7 g · m/m²), or systemic and pulmonary vascular resistances (1,675 ± 333 to 1,513 ± 508 and 191 ± 78 to 170 ± 109 dynes · s · cm^-5 respectively, all differences not significant). Nalbuphine also significantly reduced respiratory rate (32 ± 8 to 26 ± 8 resp/min, p < 0.05) and pH (7.45 ± 0.04 to 7.41 ± 0.03, p < 0.05) and increased arterial PCO₂ (32 ± 6 to 35 ± 6 mm Hg, p < 0.05) without any major change in arterial PO₂ (63 ± 13 to 66 ± 17 mm Hg, difference not significant). All these changes were comparable with morphine sulfate and no statistical difference was noted between the effects induced by both drugs. Nalbuphine's dose ranged from 5 to 30 mg (mean ± standard deviation 17 ± 8 mg) and could not be predicted from baseline hemodynamic and respiratory values.