Importance Opioid-induced ventilatory depression and hypoxemia is common, severe, and often unrecognized in postoperative patients. To the extent that nonopioid analgesics reduce opioid consumption, they may decrease postoperative hypoxemia. Objective To test the hypothesis that duration of hypoxemia is less in patients given intravenous acetaminophen than those given placebo. Design, Setting, and Participants Randomized, placebo-controlled, double-blind trial conducted at 2 US academic hospitals among 570 patients who were undergoing abdominal surgery, enrolled from February 2015 through October 2018 and followed up until February 2019. Interventions Participants were randomized to receive either intravenous acetaminophen, 1 g (n = 289), or normal saline placebo (n = 291) starting at the beginning of surgery and repeated every 6 hours until 48 postoperative hours or hospital discharge, whichever occurred first. Main Outcomes and Measures The primary outcome was the total duration of hypoxemia (hemoglobin oxygen saturation [Spo2] <90%) per hour, with oxygen saturation measured continuously for 48 postoperative hours. Secondary outcomes were postoperative opioid consumption, pain (0- 10-point scale; 0: no pain; 10: the most pain imaginable), nausea and vomiting, sedation, minimal alveolar concentration of volatile anesthetic, fatigue, active time, and respiratory function. Results Among 580 patients randomized (mean age, 49 years; 48% women), 570 (98%) completed the trial. The primary outcome, median duration with Spo2 of less than 90%, was 0.7 (interquartile range [IQR], 0.1-5.1) minutes per hour among patients in the acetaminophen group and 1.1 (IQR, 0.1-6.6) minutes per hour among patients in the placebo group (P = .29), with an estimated median difference of -0.04 (95% CI,-0.18 to 0.11) minutes per hour. None of the 8 secondary end points differed significantly between the acetaminophen and placebo groups. Mean pain scores within initial 48 postoperative hours were 4.2 (SD, 1.8) in the acetaminophen group and 4.4 (SD, 1.8) in the placebo group (difference, -0.28; 95% CI, -0.71 to 0.15); median opioid use in morphine equivalents was 50 mg (IQR, 18-122 mg) and 58 mg (IQR, 24-151 mg) , respectively, with a ratio of geometric means of 0.86 (95% CI, 0.61-1.21). Conclusions and Relevance Among patients who underwent abdominal surgery, use of postoperative intravenous acetaminophen, compared with placebo, did not significantly reduce the duration of postoperative hypoxemia over 48 hours. The study findings do not support the use of intravenous acetaminophen for this purpose. Trial Registration ClinicalTrials.gov Identifier: NCT02156154.

中文翻译：

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静脉注射对乙酰氨基酚对腹部手术后低氧血症的影响

重要性 阿片类药物引起的通气抑制和低氧血症在术后患者中很常见、很严重，而且常常未被发现。就非阿片类镇痛药减少阿片类药物的消耗而言，它们可能会减少术后低氧血症。目的 检验以下假设：静脉注射对乙酰氨基酚的患者的低氧血症持续时间少于安慰剂的患者。设计、设置和参与者 在美国 2 家学术医院对 570 名接受腹部手术的患者进行的随机、安慰剂对照、双盲试验，从 2015 年 2 月至 2018 年 10 月入组并随访至 2019 年 2 月。接受静脉注射对乙酰氨基酚，1 g (n = 289)，或生理盐水安慰剂（n = 291）在手术开始时开始，每 6 小时重复一次，直到术后 48 小时或出院，以先发生者为准。主要结果和测量 主要结果是每小时低氧血症的总持续时间（血红蛋白氧饱和度 [Spo2] <90%），并在术后 48 小时内连续测量氧饱和度。次要结果是术后阿片类药物消耗、疼痛（0-10 分制；0：无痛；10：可想象的最痛）、恶心和呕吐、镇静、挥发性麻醉剂的最低肺泡浓度、疲劳、活动时间和呼吸功能. 结果 在随机分配的 580 名患者中（平均年龄 49 岁；48% 为女性），570 名 (98%) 完成了试验。主要结果，即 Spo2 低于 90% 的中位持续时间为 0.7（四分位距 [IQR]，0.1-5。1) 对乙酰氨基酚组患者每小时分钟数和安慰剂组患者每小时 1.1 (IQR, 0.1-6.6) 分钟 (P = .29)，估计中位数差异为 -0.04 (95% CI,- 0.18 到 0.11) 分钟/小时。对乙酰氨基酚组和安慰剂组的 8 个次要终点均无显着差异。对乙酰氨基酚组术后最初 48 小时内的平均疼痛评分为 4.2（SD，1.8），安慰剂组为 4.4（SD，1.8）（差异，-0.28；95% CI，-0.71 至 0.15）；以吗啡当量计算的阿片类药物使用中位数分别为 50 mg（IQR，18-122 mg）和 58 mg（IQR，24-151 mg），几何平均值比为 0.86（95% CI，0.61-1.21）。结论和相关性 在接受腹部手术的患者中，与安慰剂相比，术后静脉注射对乙酰氨基酚的使用，没有显着减少术后 48 小时内低氧血症的持续时间。研究结果不支持为此目的使用静脉注射对乙酰氨基酚。试验注册 ClinicalTrials.gov 标识符：NCT02156154。