Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942008000300006
Brazilian Journal of Anesthesiology
Scientific Article

Comparação das alterações histológicas da medula espinal e neurológicas de cobaias após anestesia subaracnóidea com grandes volumes de bupivacaína racêmica, de mistura com excesso enantiomérico de 50% de bupivacaína (S75-R25) e de levobupivacaína

Comparison of histologic spinal cord and neurologic changes in guinea pigs after subarachnoid block with large volumes of racemic bupivacaine, 50% enantiomeric excess bupivacaine (S75-R25), and levobupivacaine

Paulo de Oliveira Vasconcelos Filho; Irimar de Paula Posso; Mariza Capelozzi; Vera Luiza Capelozzi

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Resumo

JUSTIFICATIVA E OBJETIVOS: A levobupivacaína apresenta menos efeitos colaterais sobre o sistema nervoso central do que os induzidos pela bupivacaína racêmica; entretanto, o efeito anestésico é menos intenso. Foi realizado estudo experimental para comparar efeitos adversos de grandes volumes de bupivacaína, de bupivacaína S75-R25 e de levobupivacaína quando injetados no espaço subaracnóideo de cobaias. MÉTODO: Quarenta cobaias foram divididas em quatro grupos. Anestesiadas com O2 a 100% e isoflurano a 2%, com posterior punção no espaço intervertebral L6-S1. Nos animais do Grupo I foram administrados 2 mL de solução fisiológica a 0,9%; no Grupo II, 2 mL de bupivacaína 0,5%; no Grupo III, 2 mL de bupivacaína S75-R25 0,5% e no Grupo IV, 2 mL de levobupivacaína 0,5%. Após o despertar, nos momentos 0, 60, 120 e 180 minutos, foi realizado exame neurológico, diariamente, por uma semana. Os animais foram sacrificados e submetidos à perfusão com paraformaldeído a 4%. Após a fixação, a medula espinal foi isolada por dissecção e analisada histologicamente para avaliação do grau de lesão medular. RESULTADOS: As cobaias do grupo-controle não apresentaram bloqueio nervoso. As do Grupo II apresentaram bloqueio sensitivo e motor por mais de 180 minutos. Nos Grupos III (S75-R25) e IV (levobupivacaína) houve bloqueios motor e sensitivo no momento 0 minuto; contudo, no momento 60 minutos o bloqueio motor era mínimo. Ao exame histológico, o Grupo I não apresentou alterações. No Grupo II foram encontradas alterações medulares intensas. Nos Grupos III e IV as alterações medulares foram pouco intensas. CONCLUSÕES: A levobupivacaína em grandes volumes causou pouco dano ao sistema nervoso, comparada com a bupivacaína. Entre levobupivacaína e bupivacaína S75-R25, não houve diferença estatística significativa.

Palavras-chave

ANESTÉSICOS, Local, ANESTÉSICOS, Local, ANESTÉSICOS, Local, ANIMAL, COMPLICAÇÕES, COMPLICAÇÕES, TÉCNICAS ANESTÉSICAS, Regional

Abstract

BACKGROUND AND OBJECTIVES: Levobupivacaine has less central nervous system side effects than racemic bupivacaine, but its anesthetic effect is not as intense. The objective of this experimental study was to compare the adverse effects of large volumes of bupivacaine, S75-R25 bupivacaine, and levobupivacaine injected in the subarachnoid space of guinea pigs. METHODS: Forty guinea pigs were divided in four groups. They were anesthetized with 100% O2 and 2% isoflurane, followed by puncture of the L6-S1 intervertebral space. In Group I, 2 mL of normal saline were injected; in Group II, 2 mL of 0.5% bupivacaine; in Group III, 2 mL of 0.5% S75-R25 bupivacaine, and in Group IV, 2 mL of 0.5% levobupivacaine. After the animal awakened, neurological exam was done at 0, 60, 120, and 180 minutes, and daily for one week. Animals were killed and underwent perfusion with 4% paraformaldehyde. After fixation, the spinal cord was isolated by dissection and analyzed histologically to evaluate the degree of spinal cord lesions. RESULTS: Guinea pigs in the control group did not present nervous block. Those in Group II presented sensitive and motor block for more than 180 minutes. Animals in Groups III (S75-R25) and IV (levobupivacaine) developed sensitive and motor blockade at moment 0, but at 60 minutes the motor blockade was minimal. Histologic exam in Group I showed no changes. In Group II, severe spinal cord changes were observed. In Groups III and IV, spinal cord changes were mild. CONCLUSIONS: Large volumes of levobupivacaine caused little damage in the central nervous system when compared with bupivacaine. Statistically significant changes were not observed between levobupivacaine and S75-R25 bupivacaine.

Keywords

ANESTHETICS, Local, ANESTHETICS, Local, ANESTHETICS, Local, ANESTHETIC TECHNIQUE, Regional, ANIMAL, COMPLICATIONS, COMPLICATIONS

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