Hemodynamic effects of metocurine during isoflurane anesthesia

Anesthesia was induced in 42 adults with thiopentone 3-7 mg/kg i.v. and maintained with isoflurane at a constant inspired concentration of 1-2%. After 30 min of hemodynamic stabilization with continuous muscle relaxation and an absence of surgical stimulation, each patient was randomly assigned to one of four metocurine dosage groups: I - control (n = 11); II - 0.2 mg/kg (n = 10); III - 0.3 mg/kg (n = 10); and IV - 0.4 mg/kg (n = 11). There were no significant hemodynamic changes in Groups I or II. In Groups III and IV mean arterial pressure (MAP) decreased 32% and 26% respectively, and systemic vascular resistance (SVR) decreased 42% and 36%, respectively (P less than 0.01). In Group IV, an increase of 24% in cardiac output was also significant (P less than 0.05). These results, especially in Group IV patients, stand in marked contrast to the lack of hemodynamic effects produced by metocurine during balanced anesthesia.