Shir Y, Raja S N, Frank S M
Johns Hopkins University School of Medicine, Baltimore, Maryland.
Anesthesiology. 1994 Jan;80(1):49-56. doi: 10.1097/00000542-199401000-00011.
Although preemptive analgesia has been shown to decrease postinjury pain in animals, studies in humans have provided controversial results. The authors studied whether surgical epidural anesthesia with local anesthetics could affect postoperative pain and analgesic demands, when compared with general anesthesia.
Male patients scheduled for radical retropubic prostatectomy were randomly assigned to receive epidural anesthesia only (EA, n = 34), combined epidural and general anesthesia (EG, n = 32), or general anesthesia only (GA, n = 30). A lumbar epidural catheter was inserted and tested in all patients. In the EA group, an induction dose of 0.25 ml/kg epidural bupivacaine (0.5%) was followed during surgery by a continuous infusion of 0.1 ml.kg-1.h-1 0.125% bupivacaine. In the EG group, 0.2 ml/kg epidural bupivacaine (0.5%) was injected after induction of general anesthesia but before surgery, followed by epidural infusion of 0.1 ml.kg-1.h-1 0.125% bupivacaine. In the GA group, anesthesia was maintained with morphine, isoflurane, and N2O. Epidural patient-controlled analgesia (PCA) was provided with bupivacaine and fentanyl for all patients in the postoperative period. Postoperative pain scores and analgesic requirements were examined and compared between groups every 4-8 h for 3-5 postoperative days.
Intraoperatively, EA patients received significantly more epidural bupivacaine than EG patients (129 +/- 6 mg vs. 98 +/- 6 mg, respectively. Recovery room median residual sensory level in EA patients (T6 +/- 2) was significantly higher than in EG patients (T10 +/- 2). PCA demand was greater in the GA and EG groups when compared with the EA group in postoperative days 2 (126 +/- 9 ml, 112 +/- 9 ml, 90 +/- 6 ml, respectively; P = 0.01) and 3 (89 +/- 10 ml, 83 +/- 9 ml, 48 +/- 5 respectively; P = 0.005). There was no difference in PCA demand between the GA and EG groups in the postoperative period. No significant clinical differences in postoperative mean pain scores were recorded in the first 5 days after surgery in the three anesthetic groups (range 0-2/10).
In patients undergoing lower abdominal surgery, the neuraxial blockade and surgical anesthesia achieved by epidural local anesthetics was associated with decreased postoperative analgesic demands. Lower postoperative analgesic requirements in the EA group, when compared with both the EG and GA groups, indicate that: (1) EA patients had less postoperative pain, and (2) an efficient intraoperative blockade of noxious afferent signals to the central nervous system is fundamental in reducing postoperative pain.
尽管预先镇痛已被证明可减轻动物损伤后的疼痛，但人体研究结果却存在争议。作者研究了与全身麻醉相比，局部麻醉药用于手术硬膜外麻醉是否会影响术后疼痛及镇痛需求。
计划行耻骨后根治性前列腺切除术的男性患者被随机分为仅接受硬膜外麻醉组（EA组，n = 34）、硬膜外与全身联合麻醉组（EG组，n = 32）或仅接受全身麻醉组（GA组，n = 30）。所有患者均插入腰段硬膜外导管并进行测试。EA组术中先给予0.25 ml/kg的硬膜外布比卡因（0.5%）诱导剂量，随后在手术期间持续输注0.1 ml·kg⁻¹·h⁻¹的0.125%布比卡因。EG组在全身麻醉诱导后但手术前注射0.2 ml/kg的硬膜外布比卡因（0.5%），随后硬膜外输注0.1 ml·kg⁻¹·h⁻¹的0.125%布比卡因。GA组用吗啡、异氟烷和N₂O维持麻醉。术后所有患者均使用布比卡因和芬太尼进行硬膜外患者自控镇痛（PCA）。术后3至5天，每4 - 8小时检查并比较各组的术后疼痛评分及镇痛需求。
术中，EA组患者接受的硬膜外布比卡因显著多于EG组（分别为129 ± 6 mg和98 ± 6 mg）。EA组患者恢复室的中位残余感觉平面（T6 ± 2）显著高于EG组（T10 ± 2）。术后第2天（分别为126 ± 9 ml、112 ± 9 ml、90 ± 6 ml；P = 0.01）和第3天（分别为89 ± 10 ml、83 ± 9 ml、48 ± 5 ml；P = 0.005），GA组和EG组的PCA需求高于EA组。术后GA组和EG组之间的PCA需求无差异。术后前5天，三个麻醉组的术后平均疼痛评分无显著临床差异（范围为0 - 2/10）。
在接受下腹部手术的患者中，硬膜外局部麻醉药实现的神经轴阻滞和手术麻醉与术后镇痛需求减少相关。与EG组和GA组相比，EA组术后镇痛需求较低，这表明：（1）EA组患者术后疼痛较轻；（2）术中有效阻断有害传入信号至中枢神经系统是减轻术后疼痛的关键。
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