罗哌卡因用于老年人髋关节手术腰麻的最低有效浓度

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。

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

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.