罗哌卡因用于老年人髋关节手术腰麻的最低有效浓度

Minimum effective local anesthetic concentration of intrathecal ropivacalne for hip surgery in the elderly patients

目的研究罗哌卡因用于老年人髋关节手术患者腰麻的最低有效浓度（MLAC）。方法择期行下肢手术老年患者20例，ASAⅡ～Ⅲ级，年龄65—88岁，选择L3-4间隙穿刺，第1例蛛网膜下腔注入0．40％罗哌卡因，其后各患者所用浓度按序贯法调整，浓度变化梯度为0．02％。观察感觉阻滞起效时间、感觉阻滞达到的最高平面、感觉阻滞持续时间、下肢运动阻滞的Bromage分级、辅助药的应用和麻醉相关并发症。根据Dixon-Massey法计算罗哌卡因MLAC。结果罗哌卡因MLAC为0．29％（95％C10．26％-0．31％）。结论连续腰麻应用于老年人下肢手术，可使用低浓度罗哌卡因，更有利于血流动力学的稳定。

Objective To determine the minimum local anesthetic concentration（MLAC） of intrathecal ropivacaine for hip surgery in the elderly patients. Methods 20 ASA Ⅱ -Ⅲ patients aged 65 - 68 years undergoing the hip surgery were enrolled. Continuous spinal anesthesia was performed at L3.4 interspace. The initial concentration of ropivacaine was 0. 4%. The next concentration was determined by the response of the previous patient： the effective concentration resulted in a 0.02% decrease, and an ineffective concentration resulted in a 0. 02% increase. The onset time, the block height, the duration of block,the modified Bromage scale, the assisted medicine and the relative complications were recorded. The MLAC was calculated by the Dixon-Massey method. Results The MLAC of ropivacaine was 0. 29% （95% CI 0.26% - 0. 31% ）. Conclusion This concentration is significantly lower than the usual for single-shot spinal anesthesia. Continuous spinal anesthesia allows the lower concentration of local anesthetic for lower limbs surgery in the elderly patients, provides greater haemodynamic stability without compromising patient comfort.