To delineate some clinical features of an accidental intravascular injection of local anesthetic solution containing epinephrine during the attempt of regional block, the interaction between intravenous lidocaine and epinephrine on hemodynamics and potassium homeostasis was investigated in halothane-anesthetized dogs using three types of combination of lidocaine and epinephrine. These included 1% plain lidocaine (10 mg/kg), 1% lidocaine-epinephrine solution (10 mg/kg-5 micrograms/kg) and epinephrine-normal saline solution (1:200,000, 5 micrograms/kg). Although lidocaine did not produce any changes in systemic or pulmonary hemodynamics, epinephrine and lidocaine-epinephrine solution produced transient multifocal premature ventricular contractions associated with huge hemodynamic changes. Lidocaine-epinephrine solution caused a 43% increase in mean arterial pressure, a 107% increase in mean pulmonary artery pressure and a 244% increase in pulmonary capillary wedge pressure (p less than 0.05). These changes did not differ from those observed following epinephrine. In contrast, stroke volume decreased significantly to 70% of control after lidocaine-epinephrine, while neither epinephrine nor lidocaine produced a significant change. Lidocaine did not affect plasma potassium concentration, whereas both epinephrine and lidocaine-epinephrine produced significant increase in plasma potassium concentration (K+; 2.0 +/- 0.7 mEq/l with epinephrine and 1.8 +/- 1.2 mEq/l with lidocaine-epinephrine), which subsequently decreased to below control.