Anesthesia (19)

Abstract

Respiratory gas exchange and hemodynamics during lumbar epidural anesthesia: effects of lidocaine with and without epinephrine. (New England Medical Center, Tufts University School of Medicine, Boston, MA) Reg Anesth Pain Med 2000;25:380–384.In this study, 12 healthy patients (age, 22 to 46 years) undergoing surgery on the knee were randomly assigned to receive either 2% lidocaine (Group L) or 2% lidocaine with epinephrine 5 μg · mL−1 (Group E), approximately 20 mL, over 10 min via lumbar epidural catheter. Total‐body oxygen consumption (VO2) and carbon dioxide production (VCO2) were determined by indirect calorimetry; hemodynamic measurements were obtained by noninvasive thoracic electrical bioimpedance. Values of VO2, VCO2, heart rate (HR), cardiac index (CI), and mean arterial blood pressure (MAP) were determined every minute and averaged every 5 min for 30 min. Comparisons were made with analysis of variance (ANOVA) (within groups) and t‐tests (between groups). Differences were considered significantly different if P < 0.05. VO2 did not change in either group, while VCO2 increased significantly by 22% at 20 min in Group E. Increases in HR were apparent in both groups, with significantly greater increases in Group E. CI did not change in Group L, but increased by 41% in Group E. MAP decreased significantly by 11% in Group E, but did not change in Group L. Conclude that the addition of epinephrine, 5 μg · mL−1, to the epidural injection of 2% lidocaine is associated with changes not only in hemodynamics, but also in respiratory gas exchange.