湿化高流量鼻导管通气不同流量预充氧对大体质指数患者行无痛胃肠镜期间氧合效应的影响

目的 探讨湿化高流量鼻导管通气（humidified high flow nasal cannula，HFNC）不同流量对大体质指数（≥24 kg/m2）患者行无痛胃肠镜诊疗过程中低氧血症发生率以及“安全时限”的影响。方法将拟行无痛胃肠镜诊疗的大体质指数患者随机分为4组（n=50），分别为HFNC 6 L/min（A组）、HFNC 20 L/min（B组）、HFNC 40 L/min（C组）、HFNC 60 L/min （D组）。预充氧5 min，流量根据随机分组结果设置。均设定吸入氧浓度50%，温度34℃。预充氧结束后缓慢静脉推注丙泊酚2～25 mg/kg。血氧饱和度（SpO2）＜90%定义为低氧血症。记录低氧血症发生率，安全时限（首次静脉注射丙泊酚至SpO2＜90%的时间）；SpO2最低值以及PETCO2最高值；严重低氧血症（SpO2＜75%）发生率；呼吸道干预措施以及诊疗期间、苏醒期、术后第5天的不良反应。结果低氧血症发生率，安全时限，以及PETCO2最高值、严重低氧血症发生率的组间比较差异无统计学意义（P>005)。4组间比较，SpO2最低值差异有统计学意义（P=0038）。两两比较，A组SpO2最低值低于D组（P=0002）。而需托下颌者4组间比较差异有统计学意义（42%、34%、34%、14%，P=0019）。两两比较，A组（6 L/min组）与D组（60 L/min组）差异有统计学意义（P=0007）;D组出现低氧血症后吸入60 L/min的高流量氧气，需托下颌的概率明显低于A组（P<005)。吸氧不耐受发生率组间比较差异有统计学意义（P<005)，以D组发生率最高（0、4%、14%、18%，P=0005）。结论HFNC预充氧，流量对大体质指数患者进行无痛胃肠镜预防低氧血症和延长耐受时间可能无显著影响。随着流量增加，托下颌的概率可能下降，但吸氧不耐受概率增加。

Influence of different flow rate pre-oxygenation of humidified high flow nasal cannula on oxygenation effect during painless gastroscopy in patients with large body mass index

Objective To investigate the effect of different HFNC （humidified high flow nasal cannula） flow rates on the incidence of hypoxemia and the "safe-time limit" during gastrointestinal endoscopy in patients with BMI≥24 kg/m2. Methods 200 patients with BMI≥24 kg/m2 were randomly divided into 4 groups（n=50）: HFNC 6 L/min （Group A）， HFNC 20 L/min （Group B）， HFNC 40 L/min （Group C）， and HFNC 60 L/min （Group D）. Pre-oxygenation was performed for 5 minutes, and the flow rate was set according to different groups. Set all the inhaled oxygen concentration to 50% and temperature to 34 ℃. Inject propofol 2-25 mg/kg intravenously after pre-oxygenation. Blood oxygen saturation （SpO2）<90% is defined as hypoxemia. Record the incidence of hypoxemia and the time from first intravenous injection of propofol to SpO2<90%， the lowest value of SpO2 and the highest value of PetCO2， the incidence of severe hypoxemia （SpO2<75%）， respiratory intervention measures and adverse reactions. Results The incidence of hypoxemia， safety-time limit， the highest value of PetCO2 and the incidence of severe hypoxemia were not significantly different among the four groups. There was significant difference in the lowest value of SpO2 among the four groups （P=0038）. The lowest SpO2 in group A was lower than that in group D （P=0002）. There were statistical differences among the four groups in requiring jaw lift （42% vs 34% vs 34% vs 14%，P=0019）， and the number of requiring jaw lift in group A was significantly higher than that in group D （P=0007）. There were statistical differences in the incidence of oxygen intolerance among the groups， with the highest incidence in group D （0 vs 4% vs 14% vs 18%， P=0005）. Conclusion HFNC pre-oxygenation at the same inhaled oxygen concentration， different flow rates may not have a significant effect on the prevention of hypoxemia and prolonging hypoxia time in patients with BMI≥24 kg/m2 undergoing gastrointestinal endoscopy. As the flow increases， the probability of jaw lift decreases， but oxygen intolerance increases.