Anesthesiology. 2021 Apr 1;134(4):541-551. doi: 10.1097/ALN.0000000000003725.
It is speculated that opioid-free anesthesia may provide adequate pain control while reducing postoperative opioid consumption. However, there is currently no evidence to support the speculation. The authors hypothesized that opioid-free balanced anesthetic with dexmedetomidine reduces postoperative opioid-related adverse events compared with balanced anesthetic with remifentanil.
Patients were randomized to receive a standard balanced anesthetic with either intraoperative remifentanil plus morphine (remifentanil group) or dexmedetomidine (opioid-free group). All patients received intraoperative propofol, desflurane, dexamethasone, lidocaine infusion, ketamine infusion, neuromuscular blockade, and postoperative lidocaine infusion, paracetamol, nefopam, and patient-controlled morphine. The primary outcome was a composite of postoperative opioid-related adverse events (hypoxemia, ileus, or cognitive dysfunction) within the first 48 h after extubation. The main secondary outcomes were episodes of postoperative pain, opioid consumption, and postoperative nausea and vomiting.
The study was stopped prematurely because of five cases of severe bradycardia in the dexmedetomidine group. The primary composite outcome occurred in 122 of 156 (78%) dexmedetomidine group patients compared with 105 of 156 (67%) in the remifentanil group (relative risk, 1.16; 95% CI, 1.01 to 1.33; P = 0.031). Hypoxemia occurred 110 of 152 (72%) of dexmedetomidine group and 94 of 155 (61%) of remifentanil group patients (relative risk, 1.19; 95% CI, 1.02 to 1.40; P = 0.030). There were no differences in ileus or cognitive dysfunction. Cumulative 0 to 48 h postoperative morphine consumption (11 mg [5 to 21] versus 6 mg [0 to 17]) and postoperative nausea and vomiting (58 of 157 [37%] versus 37 of 157 [24%]; relative risk, 0.64; 95% CI, 0.45 to 0.90) were both less in the dexmedetomidine group, whereas measures of analgesia were similar in both groups. Dexmedetomidine patients had more delayed extubation and prolonged postanesthesia care unit stay.
This trial refuted the hypothesis that balanced opioid-free anesthesia with dexmedetomidine, compared with remifentanil, would result in fewer postoperative opioid-related adverse events. Conversely, it did result in a greater incidence of serious adverse events, especially hypoxemia and bradycardia.
有人推测，无阿片类药物麻醉可能在提供足够疼痛控制的同时减少术后阿片类药物的消耗。然而，目前尚无证据支持这一推测。作者假设，与瑞芬太尼相比，含右美托咪定的无阿片类药物平衡麻醉可减少术后与阿片类药物相关的不良事件。
患者被随机分配接受术中瑞芬太尼加吗啡（瑞芬太尼组）或右美托咪定（无阿片类药物组）的标准平衡麻醉。所有患者均接受术中异丙酚、地氟烷、地塞米松、利多卡因输注、氯胺酮输注、神经肌肉阻滞以及术后利多卡因输注、对乙酰氨基酚、奈福泮和患者自控吗啡。主要结局是拔管后 48 小时内发生的与术后阿片类药物相关的不良事件（低氧血症、肠梗阻或认知功能障碍）的复合事件。主要次要结局是术后疼痛发作、阿片类药物消耗和术后恶心呕吐。
由于右美托咪定组发生五例严重心动过缓，研究提前停止。无阿片类药物组的主要复合结局发生在 156 例患者中的 122 例（78%），而瑞芬太尼组发生在 156 例患者中的 105 例（67%）（相对风险，1.16；95%CI，1.01 至 1.33；P=0.031）。低氧血症发生在无阿片类药物组的 152 例患者中的 110 例（72%）和瑞芬太尼组的 155 例患者中的 94 例（61%）（相对风险，1.19；95%CI，1.02 至 1.40；P=0.030）。肠梗阻或认知功能障碍无差异。0 至 48 小时术后吗啡累积消耗量（11mg[5 至 21]与 6mg[0 至 17]）和术后恶心呕吐（58/157[37%]与 37/157[24%]；相对风险，0.64；95%CI，0.45 至 0.90）均无阿片类药物组较低，而两组的镇痛措施相似。右美托咪定组患者的拔管时间延迟和麻醉后监护病房停留时间延长。
这项试验反驳了这样一种假设，即与瑞芬太尼相比，含右美托咪定的平衡无阿片类药物麻醉不会导致术后与阿片类药物相关的不良事件减少。相反，它确实导致了更严重的不良事件的发生率增加，尤其是低氧血症和心动过缓。
