Volumes Efetivos de Anestésicos Locais para o Bloqueio do Compartimento da Fáscia Ilíaca: Estudo Comparativo Duplamente Encoberto entre Ropivacaína a 0,5% e Bupivacaína a 0,5%* Effective Volume of Local Anesthetics for Fascia Iliac Compartment Block: A Double-Blind, Comparative Study between 0.5% Ropivacaine and 0.5% Bupivacaine

SUMMARY Helayel PE, Lobo G, Vergara R, Conceicao DB, Oliveira Filho GR –Effective Volume of Local Anesthetics for Fascia Iliac CompartmentBlock: A Double-Blind, Comparative Study between 0.5% Ropivacaineand 0.5% Bupivacaine. BACKGROUND AND OBJECTIVES: Fascia iliac compartmentblock is widely used as one of the anesthetic techniques used forsurgical interventions of the hip, thigh, and knee. The majority of thestudies have used fixed volumes of ropivacaine or bupivacaine. Theobjective of this study was to calculate the effective volume of 0.5%ropivacaine and 0.5% bupivacaine in 50% (EV50%), 95% (EV95), and99% (EV99) of the cases to achieve fascia iliac compartment block. METHODS: Fifty-one adults scheduled for elective surgical inter-ventions of the hip, femoral diaphysis, and knee underwent fasciailiac compartment block. Patients were randomly assigned toreceive either 0.5% ropivacaine (n = 25) or 0.5% bupivacaine (n =26). The success of the block was defined as a complete sensitiveblock of the anterior, medial, and lateral regions of the thigh. Thevolume of the anesthetic was determined by Massey and Dixon’sup-and-down method, while the effective volume was calculated byMassey and Dixon’s formula (EV50) and by probits regression(EV50, EV95, and EV99).