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Abstract：
BACKGROUND: Before tracheal intubation, it is essential to provide sufficient oxygen reserve for emergency patients with full stomachs. Recent studies have demonstrated that high-flow nasal oxygen (HFNO) effectively pre-oxygenates and prolongs apneic oxygenation during tracheal intubation. Despite its effectiveness, the use of HFNO remains controversial due to concerns regarding carbon dioxide clearance. The air leakage and unknown upper airway obstruction during HFNO therapy cause reduced oxygen flow above the vocal cords, possibly weaken the carbon dioxide clearance.
METHODS: Patients requiring emergency surgery who had fasted < 8 h and not drunk < 2 h were randomly assigned to the high-flow group, who received 100% oxygen at 30-60 L/min through nasopharyngeal airway (NPA), or the mask group, who received 100% oxygen at 8 L/min. PaO2 and PaCO2 were measured immediately before pre-oxygenation (T0), anesthesia induction (T1), tracheal intubation (T2), and mechanical ventilation (T3). The gastric antrum\'s cross-sectional area (CSA) was measured using ultrasound technology at T0, T1, and T3. Details of complications, including hypoxemia, reflux, nasopharyngeal bleeding, postoperative pulmonary infection, postoperative nausea and vomiting (PONV), and postoperative nasopharyngeal pain, were recorded. The primary outcomes were PaCO2 measured at T1, T2, and T3. The secondary outcomes included PaO2 at T1, T2, and T3, CSA at T1 and T3, and complications happened during this trial.
RESULTS: Pre-oxygenation was administered by high-flow oxygen through NPA (n = 58) or facemask (n = 57) to 115 patients. The mean (SD) PaCO2 was 32.3 (6.7) mmHg in the high-flow group and 34.6 (5.2) mmHg in the mask group (P = 0.045) at T1, 45.0 (5.5) mmHg and 49.4 (4.6) mmHg (P < 0.001) at T2, and 47.9 (5.1) mmHg and 52.9 (4.6) mmHg (P < 0.001) at T3, respectively. The median ([IQR] [range]) PaO2 in the high-flow and mask groups was 404.5 (329.1-458.1 [159.8-552.9]) mmHg and 358.9 (274.0-413.3 [129.0-539.1]) mmHg (P = 0.007) at T1, 343.0 (251.6-428.7 [73.9-522.1]) mmHg and 258.3 (162.5-347.5 [56.0-481.0]) mmHg (P < 0.001) at T2, and 333.5 (229.9-411.4 [60.5-492.4]) mmHg and 149.8 (87.0-246.6 [51.2-447.5]) mmHg (P < 0.001) at T3, respectively. The CSA in the high-flow and mask groups was 371.9 (287.4-557.9 [129.0-991.2]) mm2 and 386.8 (292.0-537.3 [88.3-1651.7]) mm2 at T1 (P = 0.920) and 452.6 (343.7-618.4 [161.6-988.1]) mm2 and 385.6 (306.3-562.0 [105.5-922.9]) mm2 at T3 (P = 0.173), respectively. The number (proportion) of complications in the high-flow and mask groups is shown below: hypoxemia: 1 (1.7%) vs. 9 (15.8%, P = 0.019); reflux: 0 (0%) vs. 0 (0%); nasopharyngeal bleeding: 1 (1.7%) vs. 0 (0%, P = 1.000); pulmonary infection: 4 (6.9%) vs. 3 (5.3%, P = 1.000); PONV: 4 (6.9%) vs. 4 (7.0%, P = 1.000), and nasopharyngeal pain: 0 (0%) vs. 0 (0%).
CONCLUSIONS: Compared to facemasks, pre-oxygenation with high-flow oxygen through NPA offers improved carbon dioxide clearance and enhanced oxygenation prior to tracheal intubation in patients undergoing emergency surgery, while the risk of gastric inflation had not been ruled out.
BACKGROUND: This trial was registered prospectively at the Chinese Clinical Research Registry on 26/4/2022 (Registration number: ChiCTR2200059192).
METHODS: Patients requiring emergency surgery who had fasted < 8 h and not drunk < 2 h were randomly assigned to the high-flow group, who received 100% oxygen at 30-60 L/min through nasopharyngeal airway (NPA), or the mask group, who received 100% oxygen at 8 L/min. PaO2 and PaCO2 were measured immediately before pre-oxygenation (T0), anesthesia induction (T1), tracheal intubation (T2), and mechanical ventilation (T3). The gastric antrum\'s cross-sectional area (CSA) was measured using ultrasound technology at T0, T1, and T3. Details of complications, including hypoxemia, reflux, nasopharyngeal bleeding, postoperative pulmonary infection, postoperative nausea and vomiting (PONV), and postoperative nasopharyngeal pain, were recorded. The primary outcomes were PaCO2 measured at T1, T2, and T3. The secondary outcomes included PaO2 at T1, T2, and T3, CSA at T1 and T3, and complications happened during this trial.
RESULTS: Pre-oxygenation was administered by high-flow oxygen through NPA (n = 58) or facemask (n = 57) to 115 patients. The mean (SD) PaCO2 was 32.3 (6.7) mmHg in the high-flow group and 34.6 (5.2) mmHg in the mask group (P = 0.045) at T1, 45.0 (5.5) mmHg and 49.4 (4.6) mmHg (P < 0.001) at T2, and 47.9 (5.1) mmHg and 52.9 (4.6) mmHg (P < 0.001) at T3, respectively. The median ([IQR] [range]) PaO2 in the high-flow and mask groups was 404.5 (329.1-458.1 [159.8-552.9]) mmHg and 358.9 (274.0-413.3 [129.0-539.1]) mmHg (P = 0.007) at T1, 343.0 (251.6-428.7 [73.9-522.1]) mmHg and 258.3 (162.5-347.5 [56.0-481.0]) mmHg (P < 0.001) at T2, and 333.5 (229.9-411.4 [60.5-492.4]) mmHg and 149.8 (87.0-246.6 [51.2-447.5]) mmHg (P < 0.001) at T3, respectively. The CSA in the high-flow and mask groups was 371.9 (287.4-557.9 [129.0-991.2]) mm2 and 386.8 (292.0-537.3 [88.3-1651.7]) mm2 at T1 (P = 0.920) and 452.6 (343.7-618.4 [161.6-988.1]) mm2 and 385.6 (306.3-562.0 [105.5-922.9]) mm2 at T3 (P = 0.173), respectively. The number (proportion) of complications in the high-flow and mask groups is shown below: hypoxemia: 1 (1.7%) vs. 9 (15.8%, P = 0.019); reflux: 0 (0%) vs. 0 (0%); nasopharyngeal bleeding: 1 (1.7%) vs. 0 (0%, P = 1.000); pulmonary infection: 4 (6.9%) vs. 3 (5.3%, P = 1.000); PONV: 4 (6.9%) vs. 4 (7.0%, P = 1.000), and nasopharyngeal pain: 0 (0%) vs. 0 (0%).
CONCLUSIONS: Compared to facemasks, pre-oxygenation with high-flow oxygen through NPA offers improved carbon dioxide clearance and enhanced oxygenation prior to tracheal intubation in patients undergoing emergency surgery, while the risk of gastric inflation had not been ruled out.
BACKGROUND: This trial was registered prospectively at the Chinese Clinical Research Registry on 26/4/2022 (Registration number: ChiCTR2200059192).
摘要：
背景：气管插管前，为胃饱满的急诊患者提供足够的氧气储备至关重要。最近的研究表明，高流量鼻氧（HFNO）可有效地预氧合并延长气管插管期间的呼吸氧合。尽管有效,由于对二氧化碳清除的担忧,HFNO的使用仍存在争议.HFNO治疗期间漏气和未知的上呼吸道阻塞导致声带上方的氧气流量减少，可能会削弱二氧化碳的清除能力.
方法：需要紧急手术且禁食<8小时且未饮酒<2小时的患者被随机分配到高流量组，通过鼻咽气道（NPA）以30-60L/min的速度接受100％氧气，或遮罩组，以8升/分钟的速度接受100%氧气。在预氧合（T0）之前立即测量PaO2和PaCO2，麻醉诱导（T1），气管插管（T2），机械通气（T3）。使用超声技术在T0，T1和T3测量胃窦的横截面积（CSA）。并发症的细节，包括低氧血症,反流,鼻咽出血,术后肺部感染,术后恶心和呕吐（PONV），术后鼻咽疼痛，被记录下来。主要结果是在T1、T2和T3测量的PaCO2。次要结局包括T1，T2和T3时的PaO2，T1和T3时的CSA，以及在该试验期间发生的并发症。
结果：115例患者通过NPA（n=58）或面罩（n=57）的高流量氧气进行预氧合。T1时，高流量组的平均（SD）PaCO2为32.3（6.7）mmHg，面罩组为34.6（5.2）mmHg（P=0.045），T2时45.0（5.5）mmHg和49.4（4.6）mmHg（P<0.001），T3时分别为47.9（5.1）mmHg和52.9（4.6）mmHg（P<0.001）。高流量和面罩组的平均（[IQR][范围]）PaO2分别为404.5（329.1-458.1[159.8-552.9]）mmHg和358.9（274.0-413.3[129.0-539.1]）mmHg（P=0.007）在T1，343.0（251.6-428.7[73.9-522.1]）mmHg和258.3（1446.6时41.0（162.5-53.5P高流量和面罩组中的CSA在T1为371.9（287.4-557.9[129.0-991.2]）mm2和386.8（292.0-537.3[88.3-1651.7]）mm2（P=0.920）和452.6（343.7-618.4[161.6-988.1]）mm2和385.6（306.3-562.0[105.5-922.9]），T3（P=0.173）分别。高流量和面罩组中并发症的数量（比例）如下所示：低氧血症：1（1.7％）与9（15.8%，P=0.019）；反流：0（0%）vs.0（0％）；鼻咽出血：1（1.7％）与0(0%，P=1.000）；肺部感染：4（6.9%）与3（5.3%，P=1.000）；PONV：4（6.9%）与4（7.0%，P=1.000),鼻咽疼痛：0（0％）与0(0%)。
结论：与口罩相比，通过NPA的高流量氧气预氧合可改善接受紧急手术的患者气管插管前的二氧化碳清除和增强氧合。而胃膨胀的风险尚未被排除。
背景：该试验于2022年4月26日在中国临床研究注册中心进行了前瞻性注册（注册号：ChiCTR2200059192）。
方法：需要紧急手术且禁食<8小时且未饮酒<2小时的患者被随机分配到高流量组，通过鼻咽气道（NPA）以30-60L/min的速度接受100％氧气，或遮罩组，以8升/分钟的速度接受100%氧气。在预氧合（T0）之前立即测量PaO2和PaCO2，麻醉诱导（T1），气管插管（T2），机械通气（T3）。使用超声技术在T0，T1和T3测量胃窦的横截面积（CSA）。并发症的细节，包括低氧血症,反流,鼻咽出血,术后肺部感染,术后恶心和呕吐（PONV），术后鼻咽疼痛，被记录下来。主要结果是在T1、T2和T3测量的PaCO2。次要结局包括T1，T2和T3时的PaO2，T1和T3时的CSA，以及在该试验期间发生的并发症。
结果：115例患者通过NPA（n=58）或面罩（n=57）的高流量氧气进行预氧合。T1时，高流量组的平均（SD）PaCO2为32.3（6.7）mmHg，面罩组为34.6（5.2）mmHg（P=0.045），T2时45.0（5.5）mmHg和49.4（4.6）mmHg（P<0.001），T3时分别为47.9（5.1）mmHg和52.9（4.6）mmHg（P<0.001）。高流量和面罩组的平均（[IQR][范围]）PaO2分别为404.5（329.1-458.1[159.8-552.9]）mmHg和358.9（274.0-413.3[129.0-539.1]）mmHg（P=0.007）在T1，343.0（251.6-428.7[73.9-522.1]）mmHg和258.3（1446.6时41.0（162.5-53.5P高流量和面罩组中的CSA在T1为371.9（287.4-557.9[129.0-991.2]）mm2和386.8（292.0-537.3[88.3-1651.7]）mm2（P=0.920）和452.6（343.7-618.4[161.6-988.1]）mm2和385.6（306.3-562.0[105.5-922.9]），T3（P=0.173）分别。高流量和面罩组中并发症的数量（比例）如下所示：低氧血症：1（1.7％）与9（15.8%，P=0.019）；反流：0（0%）vs.0（0％）；鼻咽出血：1（1.7％）与0(0%，P=1.000）；肺部感染：4（6.9%）与3（5.3%，P=1.000）；PONV：4（6.9%）与4（7.0%，P=1.000),鼻咽疼痛：0（0％）与0(0%)。
结论：与口罩相比，通过NPA的高流量氧气预氧合可改善接受紧急手术的患者气管插管前的二氧化碳清除和增强氧合。而胃膨胀的风险尚未被排除。
背景：该试验于2022年4月26日在中国临床研究注册中心进行了前瞻性注册（注册号：ChiCTR2200059192）。
