Plasma lidocaine concentrations during continuous epidural infusion of lidocaine with and without epinephrine

Plasma lidocaine concentrations were measured over a five-hour period in 20 patients following continuous epidural infusion of lidocaine for surgical anaesthesia. Patients were divided into two groups: Group I received plain lidocaine; Group II received lidocaine with epinephrine. Patients initially received 10 ml followed by a constant infusion of 10 ml.hr-1 of two per cent lidocaine. The mean plasma concentrations of lidocaine were significantly higher for the first 40 min in Group I than in Group II. However, from one to five hours, there was no significant difference between the groups. These results demonstrate that the addition of epinephrine to lidocaine does not decrease the plasma concentration of lidocaine during continuous epidural infusion for long operations.