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Onset of Epidural Blockade After Plain or Alkalinized 0.5% Bupivacaine

Verborgh Christian MD; Claeys, Marie-Anne MD; Camu, Frederic MD
Anesthesia & Analgesia: October 1991

This double-blind study investigated the effect of adding 1.4% bicarbonate to 0.5% bupivacaine on onset time of sensory and motor blockade after epidural administration. Forty patients were randomly divided into one of two groups. Group 1 received 20 mL of 0.5% bupivacaine (pH, 5.58 ± 0.12) and group 2 received 20 mL of 0.5% bupivacaine + 0.6 mL of 1.4% bicarbonate (pH, 6.53 ± 0.06). Onset of temperature sensation loss occurred at L-1 after 5 min in both groups. The first signs of motor impairment were seen after 4 min in three patients in group 1 and two patients in group 2. Maximum motor blockade was reached after 30 min in group 1 and after 36 min in group 2. No difference in motor blockade or upward spread of anesthesia was noted between the two groups. The authors conclude that alkalinization of 0.5% bupivacaine offers no improvement in the onset of epidural blockade.

Address correspondence to Dr. Verborgh, Academisch Ziekenhuis V.U.B., Department of Anaesthesiology, Laarbeeklaan 101, B-1090 Brussels, Belgium.

© 1991 International Anesthesia Research Society