Effect of alkalinized lidocaine on onset and duration of epidural anesthesia in orthopedic surgery

ABSTRACT

Forty adult patients having epidural anesthesia for lower extremity orthopedic procedures were assigned to four groups. Group I patients were given a commercially prepared 2% lidocaine solution whose pH was 6.3. Group II patients were given commercially prepared 2% lidocaine solution plus ImEq [1m1] NaHCO3 per 10 ml of lidocaine whose pH was 6.8. Group III patients received the commercial solution of 2% lidocaine plus 3 ml molar NaHCO3 [3mEq] added per 10 ml lidocaine, the solution pH was 7.088. Group IV patients were given a commercially prepared 2% lidocaine solution plus 7 ml molar NaHCO3 [7mEq] freshly added per 10 ml anesthetic solution. The onset of epidural anesthesia was accelerated by alkalinization of lidocaine. Group IV had the fastest mean onset time. The duration of analgesia was significantly longer in the pH adjusted groups. There was a significant decrease in MABP from the preoperative value in all the four groups, and the baseline of systolic and diastolic blood pressure did not differ in the alkalinized and control groups