摘要目的：比较三种头高位角度对蛛网膜下隙麻醉后直接俯卧位阻滞平面的影响，以获得吻合器痔上黏膜环切吻合术（PPH）的适宜头高位角度。方法将60例择期行PPH的患者按随机数字表法分为10°组、20°组和30°组，每组20例。均选取L3～4棘突间隙行蛛网膜下隙穿刺，穿刺成功后注入0.5%重密度罗哌卡因2 ml，麻醉完成后分别调整手术床为头高位10°（10°组）、20°（20°组）、30°（30°组），同时让患者俯卧，手术开始前调整手术床为水平位。蛛网膜下隙麻醉注药10 min后完成折刀位。观察注药后感觉阻滞情况、循环功能变化、麻醉效果及围手术期不良反应发生情况。结果三组手术开始时间和平面固定时间比较差异无统计学意义（P＞0.05）。10°组调整水平位前感觉阻滞平面上界、完成折刀位前感觉阻滞平面上界、感觉阻滞最高平面明显高于20°组和30°组[T（10.47±0.65）比T（12.36±0.72）和T（12.50±0.54）、T（10.12±0.56）比T（11.82±0.66）和T（11.99±0.72）、T（9.53±0.71）比T（11.32±0.78）和T（11.54±0.83）]，差异有统计学意义（P＜0.05）；而20°组与30°组比较差异无统计学意义（P＞0.05）。10°组注药后15、20 min 收缩压、舒张压明显低于20°组和30°组[收缩压：（120.40±7.38）mmHg （1 mmHg =0.133 kPa）比（131.82±7.88）和（130.47±7.57）mmHg、（119.55±7.65）mmHg 比（131.25±9.67）和（130.23±8.69）mmHg；舒张压：（63.74±6.54）mmHg 比（71.36±8.49）和（74.32±7.54）mmHg、（61.59±6.23）mmHg比（72.98±7.39）和（73.75±6.34）mmHg]，差异有统计学意义（P＜0.05）；而20°组和30°组比较差异无统计学意义（P＞0.05）。三组均未出现麻醉效果差的患者，但30°组4例为良。10°组各出现了2例低血压和心动过缓。结论蛛网膜下隙麻醉后即刻俯卧位可以通过调整头高位的角度来获得适宜的麻醉平面，PPH比较适宜头高位角度是20°。

abstractsObjective To compare the effect of three kinds of reverse trendelenburg position angle in block plane of prone position after subarachnoid anesthesia, in order to acquire the conformable reverse trendelenburg position angle of prolapse and hemorrhoids (PPH). Methods Sixty patients having underwent the selective PPH were divided into 10° group, 20° group and 30° group by random digits table method with 20 cases each. Subarachnoid puncture was performed in the L3 - 4 processus spinosus gap, then 0.5%heavy density ropivacaine 2 ml was injected. After anesthesia, the operation bed was adjusted to reverse trendelenburg position 10° (10° group), 20° (20° group) and 30° (30° group). At the same time the patients changed to prone position, and the operation bed was changed to horizontal position before operation. The patients changed to jackknife position 10 min after drug injection of subarachnoid anesthesia. The sensory blockade after drug infusion, circulation function change, anesthetic effect and perioperative adverse reaction were observed. Results There were no statistical differences in operation start time and fixed time of anesthesia plane among 3 groups (P>0.05). The upper bound of sensory nerve block before horizontal position, upper bound of sensory nerve block before jackknife position, highest plane of sensory nerve block in 10° group were significantly higher than those in 20° group and 30° group: T(10.47 ± 0.65) vs. T(12.36 ± 0.72) and T(12.50 ± 0.54), T(10.12 ± 0.56) vs. T(11.82 ± 0.66) and T(11.99 ± 0.72), T(9.53 ± 0.71) vs. T(11.32 ± 0.78) and T(11.54 ± 0.83), and there were statistical differences (P<0.05); but there were no statistical difference between 20° group and 30° group (P>0.05). The systolic blood pressure and diastolic blood pressure levels 15 and 20 min after drug infusion in 10° group were significantly lower than those in 20° group and 30° group, systolic blood pressure:(120.40 ± 7.38) mmHg (1 mmHg=0.133 kPa) vs. (131.82 ± 7.88) and (130.47 ± 7.57) mmHg, (119.55 ± 7.65) mmHg vs. (131.25 ± 9.67) and (130.23 ± 8.69) mmHg, diastolic blood pressure: (63.74 ± 6.54) mmHg vs. (71.36 ± 8.49) and (74.32 ± 7.54) mmHg, (61.59 ± 6.23) mmHg vs. (72.98 ± 7.39) and (73.75 ± 6.34) mmHg, and there were statistical differences (P<0.05);but there were no statistical difference between 20° group and 30° group (P>0.05). No patients′ anesthesia effect was poor in 3 groups, but 4 cases in 30° group were good. Hypotension and tachycardia occurred in 2 cases in 10° group, respectively. Conclusions Immediately prone position after subarachnoid anesthesia can be adjusted by reverse trendelenburg position angle to get the appropriate level of anesthesia, and conformable reverse trendelenburg position angle of PPH is 20°.