Effect of increasing doses of magnesium in experimental pulmonary hypertension after acute pulmonary embolism.

Abstract

To investigate the dose-related effects of magnesium on pulmonary vascular resistance and associated changes in cardiac output in porcine micro-embolic pulmonary hypertension. Prospective, interventional animal study. University animal laboratory. Forty anaesthetised and ventilated piglets. Right heart catheterisation for the measurement of cardiac output, pulmonary artery pressure, central venous pressure and pulmonary capillary wedge pressure; arterial cannulation for measurement of arterial pressures and ionised magnesium levels; calculation of pulmonary and systemic vascular resistance before and after induction of acute pulmonary micro-embolism, and without or with the administration of magnesium (0.5, 1.0, 2.0 mmol/kg bolus and 1 mmol/kg bolus followed by 1 mmol/kg per h continuous infusion). The bolus administration of increasing doses of magnesium (0.5, 1.0, 2.0 mmol/kg) was associated with an increase in ionised serum magnesium levels and a dose-dependent decrease of mean pulmonary arterial pressure, an increase of cardiac output and a decrease of pulmonary vascular resistance. This effect was sustained after bolus administration (1 mmol/kg) followed by a continuous infusion of magnesium (1 mmol/kg per h). Magnesium has a directly dose-dependent beneficial effect on the circulation in acute embolic pulmonary hypertension and improves cardiocirculatory impairment in massive pulmonary embolism (PE).