不同的吸入氧浓度对小儿先天性心脏病围术期气体交换的影响

目的:纯氧常规用于麻醉前预先吸氧和麻醉诱导，但吸高浓度氧会发生肺不张，可在全麻期间损害肺气体交换，本研究以吸入氧浓度（fraction of inspiration oxygen，FiO2）为纯氧(1 L/L)通气为对照，观察气管插管后FiO2为0.5 L/L混合空气通气对气体交换的影响。方法: 先天性心脏病（非紫绀型）手术患者102名，年龄1月～13岁，均以1 L/L O2在麻醉前预先吸氧3 min和（麻醉诱导时）面罩通气2 min，接下来气管插管。这些患者随机分为2组:混合通气组（51例，行FiO2为0.5 L/L O2通气），纯氧通气组（51例，行1 L/L O2通气）。分别于预先吸氧前和气管插管后30 min、入ICU、拔管后30 min以及术后前3 d做动脉血气分析，并计算动脉血氧分压（PaO2）/FiO2比值。结果: PaO2术后在入ICU（0.6 L/L FiO2）、拔管后30 min(1.5 L/min)面罩吸氧两个时间点，动脉血氧PaO2在混合通气组明显高于纯氧通气组，PaO2/FiO2值在插管后30 min、入ICU（0.6 L/L FiO2）、拔管后30 min(1.5 L/min)面罩吸氧等时间点混合通气组明显高于纯氧通气组（P<0.05），且混合通气组的ICU机械通气时间、住留时间及住院时间均明显缩短。结论: 先天性心脏病（非紫绀型）手术患儿全麻时，混合通气较纯氧通气能够显著的改善肺的气体交换功能和预后。

Influence of different types of ventilation on gas exchange in children wih congenital heart disease children during general anesthesia and postoperation

AIM: To evaluate the effect of ventilation with 0.5 L/L FiO2 in air or 1 L/L O2 following intubation on gas exchange.METHODS: One hundred and two patients(aged 1 month to 13 years) undergoing surgical cardiac intervention with congenital heart disease(CHD)(non-cyanosis) were given 1 L/L O2 for preoxygenation(3 min) and ventilation by mask(2 min).Following intubation,patients were randomly divided into two groups(51 patients in each group) and ventilated with either 0.5 L/L FiO2 in air or 1 L/L O2.Arterial blood gases were obtained for analysis before preoxygenation,30 min following intubation,on entering the ICU,30 min after extubation and 3 days postoperation.Subsequently,PaO2/FiO2 ratios were calculated.RESULTS: PaO2 values on entering ICU and 30 min after extubation were significantly improved in the group receiving 0.5 L/L FiO2 group than those in the group receiving 1 L/L O2.PaO2/FiO2 ratio in the 0.5 L/L FiO2 group was significantly improved at the following time points: 30 min after intubation,upon entering the ICU and 30 min after extubation.Mechanical ventilation time,time in ICU and length of hospitalization in 0.5 L/L FiO2 group were significantly shortened compared with those in the group receiving 1 L/L O2.CONCLUSION: During general anesthesia in children with CHD(non-cyanosis),ventilation of lungs with 0.5 L/L FiO2 is superior for improving gas exchange than ventilation of lungs with 1 L/L O2.