Brazilian Journal of Anesthesiology
https://bjan-sba.org/article/doi/10.1590/S0034-70942009000600003
Brazilian Journal of Anesthesiology
Scientific Article

Dose de bupivacaína subaracnóidea necessária para cesariana é semelhante em mulheres obesas e com peso normal

Dose requirement of intrathecal bupivacaine for cesarean delivery is similar in obese and normal weight women

Yung Lee; Mrinalini Balki; Robert Parkes; Jose C. A Carvalho

http://dx.doi.org/10.1590/S0034-70942009000600003 Braz J Anesthesiol, vol.59, n6, p.674-683, 2009
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Resumo

JUSTIFICATIVA E OBJETIVOS: Os efeitos do IMC na dispersão subaracnóidea de bupivacaína são controversos. O presente estudo avaliou a ED95 de bupivacaína subaracnóidea em cesarianas eletivas em mulheres obesas e naquelas com peso normal. MÉTODO: Foram avaliadas gestantes com peso normal (IMC < 25 kg.m-2) e obesas (IMC > 30 kg.m-2) com feto único de termo, submetidas a cesarianas eletivas. Esse foi um estudo encoberto e de alocação sequencial usando o método up-and-down (modificado pela regra de Narayana). Todas as pacientes receberam bloqueio combinado raquiperidural com administração subaracnóidea de doses variáveis de bupivacaína hiperbárica a 0,75% mais 10 µg de fentanil e 100 µg de morfina. A primeira paciente recebeu 9 mg de bupivacaína. A anestesia foi suplementada quando necessário por meio de um cateter peridural. O sucesso da anestesia, definido como bloqueio sensitivo até pelo menos T6 sem necessidade de anestesia suplementar, foi o objetivo primário. A ED95 para resultado satisfatório foi determinada por modelo logístico sem transformação logarítmica das doses. RESULTADOS: Vinte e quatro gestantes com peso normal e dezesseis gestantes obesas participaram deste estudo. A ED95 estimada para todas as pacientes foi de 12,92 mg (IC 95%: 11,49 a 34,77). A ED95 estimada para as gestantes com peso normal e as gestantes obesas foi semelhante, 12,78 mg (IC 95%: 10,75 a + infinito) e 11,86 mg (CI 95%: 11,31 a 15,61), respectivamente. CONCLUSÕES: Se a anestesia subaracnóidea com injeção única for utilizada em cesarianas, pacientes com peso normal e obesas devem receber doses semelhantes de bupivacaína hiperbárica. Apesar de não ter sido possível determinar com precisão a ED95 nesse estudo, é possível afirmar que ela é de pelo menos 11,49 mg.

Palavras-chave

ANESTESIA, Obstétrica, ANESTÉSICOS, Local, CIRURGIA, Obstétrica, DOENÇAS, Obesidade, TÉCNICAS ANESTÉTICAS, Regional

Abstract

BACKGROUND AND OBJECTIVES: The effect of BMI on the spread of intrathecal bupivacaine is controversial. This study assessed the ED95 of intrathecal bupivacaine for elective cesarean delivery in obese and normal weight women. METHODS: We studied normal weight (BMI < 25 kg.m-2) and obese (BMI > 30 kg.m-2) women with singleton term pregnancies undergoing elective cesarean delivery. The study was conducted as a single blinded, up-down sequential allocation study (modified by the Narayana rule). All patients received a combined spinal-epidural anesthesia with a variable intrathecal dose of hyperbaric 0.75% bupivacaine, plus fentanyl 10 µg and morphine 100 µg. The first patient received 9 mg of bupivacaine. Supplemental anesthesia was provided through the epidural catheter if required. The primary outcome was successful analgesia, defined as a sensory block to at least T6, and no request for supplemental anesthesia. The ED95 for the satisfactory outcome was determined by a logistic model with non-log-transformed doses. RESULTS: Twenty-four normal weight and sixteen obese patients were enrolled. The estimated ED95 for all forty patients was 12.92 mg (95% CI: 11.49 to 34.77). The estimated ED95 for the normal weight and the obese subgroups were similar at 12.78 mg (95% CI: 10.75 to + infinity) and 11.86 mg (95%CI: 11.31 to 15.61), respectively. CONCLUSIONS: If single shot spinal anesthesia is used for cesarean delivery, obese and normal weight patients should receive similar doses of hyperbaric bupivacaine. Although in our study the effective dose 95% could not be precisely determined, it is possible to state that it is at least 11.49 mg.

Keywords

ANESTHESIA, Obstetric, ANESTHETIC TECHNIQUES, Regional, ANESTHETICS, Local, DISEASES, Obesity, SURGERY, Obstetric

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