Epinephrine in spinal anesthesia
Nolte, H.; Kraus, A.
Regional-Anaesthesie 11(4): 98-104
1988
ISSN/ISBN: 0171-1946 PMID: 3222492 Document Number: 322908
Isobaric bupivacaine for spinal anesthesia has frequently proved advantageous because of its long and safe analgesia, good motor blockade and low incidence of side-effects [ 2, 9, 15, 18, 19, 23, 31, 33-35, 36]. Significant prolongation of analgesia is possible with an epinephrine concentration of as low as 1:200,000 added to bupivacain 0.5%, while optimal prolongation can be achieved by a concentration of 1:100,000. The addition of 1:50,000 epinephrine, however, does not induced any further enhancement. These results are contrary to those of Chambers [11] and Scott [30], whose short durations of action were possibly due to relative overdosage of epinephrine with a paradoxical reduction of action. The latency period until complete blockade is achieved can be reduced by high epinephrine concentrations (beginning with 1:50,000), a fact which is possibly due to a direct, receptor-induced mechanisms of epinephrine. The motor blockade of ankle and toe joints beginning from a concenration of 1:100,000 epinephrine is also prolonged significantly. Withall epinephrine concentrations, the overall duration of analgesia could be prolonged significantly, in contrast to the overall duration of motor blockade. Only with free bupivacaine solution did motor and sensory function return at more or less the same time. The period bewteen the beginning and the end of regression for both sensation and motor function was influenced only by the highest epinephrine concentration (1:50,000). This solution not only induced a reduction in motor latency, but also prolonged motor regression. Positive characteristtics were a nearly complete lack of side-effects in spite of higher epinephrine concentrations, 100% complete motor blockade, and sufficient spread of the block in all cases. These results demonstrate that the addition of 0.01 mg/ml epinephrine (1:100,000) to isobaric bupivacaine 0.5% leads to significant prolongation of its action and intensification of the motor blockade, which in some cases is markedly greater than reported in literature.