Blood gas and hemodynamic changes induced by the treatment of pulmonary congestion with vasodilators in the acute phase of myocardial infarction.

The effects of vasodilators on hemodynamics and blood gases was assessed in 31 patients suffering from acute myocardial infarction (AMI) who had clinical signs of left ventricular failure with high pulmonary wedge pressure (PWP greater than 15 mm Hg). Molsidomine (n = 10), phentolamine (n = 12) and sulmazol (n = 9) were administered intravenously to decrease the PWP by 20%. Molsidomine significantly decreased PWP after one hour with a mild increase in cardiac index (CI) inducing a slight decrease in paO2 (64 to 59 mm Hg, P less than 0.1) with no change in p-vO2. Phentolamine and Sulmazol significantly increased the CI and decreased the PWP, with a substantial increase in the pv-O2 (28 to 32 mm Hg, P less than 0.005 and 28 to 31 mm Hg, P less than 0.001) and no significant change in the paO2 (60 to 65 mm Hg, P less than 0.1 and 68 to 69 mm Hg, NS). None of these drugs significantly changes the pulmonary vascular resistance (PVR) which would explain the lack of any significant change in paO2. The treatment of pulmonary congestion in AMI by either pure venous (molsidomine) or arteriolar and venous (phentolamine and sulmazol) vasodilators does not worsen obviously pre-existant hypoxemia.