摘要目的 在围麻醉期和危重患者的通气中,高浓度氧吸入可引起肺泡不张,肺内分流率增加,长时间应用可引起肺实质损害.研究观察术后麻醉恢复期不同吸入氧浓度通气对拔管前氧储备和肺换气功能的影响,为通气选择合适的吸入氧浓度提供依据. 方法 152例不吸烟的全麻择期手术患者,进入麻醉恢复室(post anesthesia care unit,PACU)后接呼吸机,通气模式为同步间歇指令通气,调节吸入氧浓度为35％,进行肺活量膨肺的肺复原操作,操作结束后,呼吸机调回同步间歇指令通气模式.根据完全随机的原则分为4组(每组38例):0.35吸入氧浓度(fraction of inspired oxygen in nitrogen,FiO2)组,0.50FiO2组,0.75FiO2组,1.0FiO2组.通气5 min,停止通气.当血氧饱和度下降至90％,接上呼吸机.穿刺抽取足背动脉血,并根据公式计算肺内分流率(Qs/Qt)和氧合指数(PaO2/FiO2). 结果 0.35FiO2组0.50FiO2组,0.75FiO2组和1.0FiO2组的无通气时限分别为(129 ±42)、(178±61)、(340±152)、(421±153)s(P＜0.001).1.0FiO2组的无通气时限高于0.75FiO2组,但差异无统计学意义.1.0FiO2组的无通气时限明显高于0.35FiO2组和0.50FiO2组(P＜0.005)；0.75FiO2组的无通气时限非常明显高于0.35FiO2组和0.50FiO2组(P＜0.005).0.50FiO2组的无通气时限高于0.35FiO2组,但差异无统计学意义.0.35FiO2组0.50FiO2组,0.75FiO2组的肺内分流率分别为(4.1±1.1)、(4.6±1.3)、(5.1±2.5)％,均明显低于1.0FiO2组(13.1±4.5)％(P＜0.001).0.35FiO2组,0.50FiO2组和0.75FiO2组氧合指数分别为(494±75)、(523±70)、(536±80),明显高于1.0FiO2组(423±94,P＜0.005). 结论 吸入0.75的氧能够改善肺换气功能,但无通气时限减少.

abstractsBackground To observe the effects of different fractions of inspired oxygen(FiO2)during anesthesia recovery period on oxygen reserve and pulmonary gas exchange before extubation.Methods One hundred and fifty-two non-smoking patients with elective surgery done under general anesthesia were included in this study.After entering post anesthesia care unit (PACU),all the patients were mechanically ventilated with SIMV mode in FiO20.35.When a stable end-tidal oxygen concentration was achieved,a lung recruitment maneuver was performed and then the mode of ventilation went back to synchronized intermittent mandatory ventilation(SIMV).The patients were randomly assigned to 4 groups(n=38):FiO2=0.35,FiO2=0.5,FiO2=0.75,FiO2=1.0.The patients were ventilated with different concentrations of oxygen corresponding to their grouping for 5 min.The ventilator was stopped and the time of apnea tolerance was recorded.Blood samples were taken from dorsal artery of foot for blood-gas analysis.The shunt(Qs/Qt)and PaO2/FiO2 were calculated as well.Results The time to apnea tolerance were in turn(129±42),(178±61),(340±152),(421±153)s(P＜0.001)in group 0.35FiO2,group 0.50FiO2,group 0.75FiO2 and group 1.0FiO2.Compared with group 0.75FiO2,apnea tolerance in group 1.0FiO2 was longer,but it was not statistically significant.Apnea tolerance in group 1.0FiO2 was significantly longer than in group 0.35FiO2 or group 0.50FiO2.Apnea tolerance in group 0.75FiO2 was significantly longer than in group 0.35FiO2 or group 0.50FiO2.Apnea tolerance in group 0.50FiO2 was longer than in group 0.35FiO2,which was not statistically significant.Shunt after apnea were in turn(4.1±1.1),(4.6±1.3),(5.1±2.5),(13.1±4.5)％ in group 0.35FiO2,group 0.50FiO2,group 0.75FiO2 and group 1.0FiO2,respectively.Shunt in group 0.35FiO2,group 0.50FiO2 and 0.75FiO2 was significantly less than that in group 1.0FiO2(P＜0.001).PaO2/FiO2 after apnea were(494±75),(523±70),(536±80),(423±94)(P＜0.001)in the turn of group 0.35FiO2,group 0.50FiO2,group 0.75FiO2 and group 1.0FiO2.Pao2/FiO2 after apnea in group 0.35FiO2,group 0.50FiO2 and group 0.75FiO2 was significant larger than in group 1.0FiO2.Conclusions The use of 75％ oxygen can improve the pulmonary gas exchange,accompanied by shortened apnea tolerance.