Intravenous anesthesia

Abstract

Anesthesia and Pain Medicine. 2002 Dec. 6(4): 194-199
ⓒ Korean Society for Intravenous Anesthesia
  
 
 
The Effect of Epidural Lidocaine on the Change of Bispectral Index during Enflurane Anesthesia
Hye Won Shin, M.D., Hye Won Lee, M.D., Chun Hak Lim, M.D., Hun Cho, M.D., Hae Ja Lim, M.D., Suk Min Yoon, M.D., Seong Ho Chang, M.D.
Department of Anesthesiology and Pain Medicine, College of Medicine, Korea University, Seoul, Korea.
 

BACKGROUND: Neuroaxial anesthesia has been shown to potentiate sedative drug effect and to reduce minimum alveolar concentration of inhalation anesthesia. This study was done to investigate whether epidural lidocaine affect bispectral index (BIS) during enflurane anesthesia.
METHODS: Fourty-five patients undergoing lower abdominal surgery received epidural catheterization before induction with 5 mg/kg of thiopental and 0.1 mg/kg of vecuronium for tracheal intubation. Group 1 was given 1 mg/kg of 2% lidocaine IV for 5 min followed by 30microgram/kg/min and group 2, 3 were given 15 ml of 2% lidocaine epidurally for 1 min. In group 1 and 2, BIS was measured after 15 min equilibration period of 1.65 vol% (1 MAC) enflurane and at 15 min after injection of lidocaine. In group 3, BIS was measured after 15 min equilibration period of 2.47 vol% (1.5 MAC) enflurane and at 15 min after injection of lidocaine. Blood pressure and heart rate was also measured at the same time period. Epidural anesthesia was confirmed at the postoperative period.
RESULTS: The BIS of group 1 and 3 were not decreased after lidocaine injection, but the BIS of group 2 was significantly decreased after epidural lidocaine injection (61.3 +/- 6.9 vs 48.4 +/- 9.8: P < 0.05). Within the group, Systolic blood pressure decreased significantly after epidural lidocaine injection in group 2 (124.0 +/- 14.2 vs 105.6 +/- 7.3: P < 0.05) and systolic, diastolic blood pressure decreased after epidural lidocaine injection in group 3 (117.2 +/- 10.8 vs 97.1 +/- 0.8, 80.6 +/- 10.1 vs 61.2 +/- 8.0: P < 0.05). Compared to group 1, systolic blood pressure after epidural lidocaine injection was decreased in group 2 (132.6 +/- 12.3 vs 105.6 +/- 7.3: P < 0.05) and systolic, diastolic blood pressure after epidural lidocaine injection was decreased in group 3 (132.6 +/- 12.3 vs 97.1 +/- 0.8, 85.6 +/- 8.7 vs 61.2 +/- 8.0: P < 0.05). Compared to group 2, BIS before epidural lidocaine injection was decreased in group 3 (61.3 +/- 6.9 vs 50.5 +/- 6.2: P < 0.05) but BIS after epidural lidocaine injection was not changed in group 3.
CONCLUSIONS: Epidural lidocaine reduces BIS at 1.65 vol% (1 MAC) enflurane but BIS shows a ceiling effect at 2.47 vol% (1.5 MAC) enflurane.
 
Key words : Bispectral index, enflurane, epidural, general, lidocaine
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