Immediate Hemodynamic Effect of Pharmacological Doses of Methylprednisolone in Dogs, and the Influence of Speed of Injection

Publisher Website
Google Scholar
Abstract
Reports of sudden death of patients during i.v. administration of methylprednisolone (M.P.) prompted the present study of the hemodynamic effect of M.P. given i.v. to dogs. Fifteen healthy, mongrel dogs were anesthetized with thiomeburnal, fentanyl, droperidol, pancuronium and N2O/O2. With ventilation and circulation in steady state, M.P. 30 mg/kgb.w. was given i.v. either as a push bolus (n= 7) or over a5‐min period (n = 8). In the bolus group, mean aortic pressure (MAP) and systemic vascular resistance (SVR) had decreased to 72 and 60%, respectively, 1 min after the start of the steroid injection, while heart rate (HR), cardiac index (CI), mean pulmonary arterial pressure (MPAP) and left ventricular work (LVW) had not changed significantly. In the 5‐min group, the HR increased by 23 %, while the other parameters were unchanged during the injection period. Within 5 min after the termination of the steroid injection all hemodynamic parameters had returned to pre‐injection levels in both groups. Sodium, potassium, magnesium, protein and calcium in serum were unchanged in both groups during the injection period and in the following 15 min. A significant, transient fall in ionized calcium was observed in all six dogs in which this ion was measured.It was concluded that rapid i.v. injection of pharmacological doses of M.P. in hemodynamically stable, anesthehed dogs causes immediate, transient decreases in SVR and MAP. The mechanisms may be an alpha adrenergic blocking action or a direct effect on the muscles in the peripheral vessels, combined with a negative inotropic effect on the myocardium, possibly mediated through an impeded calcium release.