Inhibition by sedatives of compensatory vasoconstriction during lumbar epidural anesthesia

: Compensatory vasoconstriction in an upper extremity during lumbar epidural anesthesia contributes to the stability of hemodynamics. We measured blood flow of an index fingertip (FBF) with laser-Doppler flowmetry, surface temperature of a middle fingertip (FT), deep body temperature of the forehead (HDT) and a big toe (BDT) by an insulated thermistor probe of zero thermal flow between skin and subcutaneous tissue, and mean arterial pressure (MAP) in 16 patients undergoing elective lower abdominal surgery under lumbar epidural anesthesia. Epidural puncture was done at L1-2 (n = 2), L2-3 (n = 8) or L3-4 (n = 6), and the initial dose of 13 +/- 1 ml (mean +/- SD) of 2% plain mepivacaine (n = 14) or 2% plain lidocaine (n = 2) was injected five minutes after the test dose of 3 ml. Five minutes after the initial injection, the hypesthesia region of cold sensation examined by alcohol absorbent cotton was T9 +/- 3 (range, T2-T12) at the upper limit and S2 +/- 2 (range, L2-S3) at the lower limit. After determination of the hypesthesia region, a combination of butorphanol 1.0 +/- 0.1 mg and midazolam 2.0 +/- 0.9 mg or diazepam 7.5 +/- 2.5 mg alone was administered intravenously. The difference between HDT and BDT decreased significantly from 6.4 degrees C (P < 0.01) at the time of test dose injection to 0.4 degrees C (P < 0.001) 20 minutes after the initial dose injection of local anesthetics. FBF showed a twofold significant increase (P < 0.01) 20 minutes after the initial dose injection.(ABSTRACT TRUNCATED AT 250 WORDS)