超声监测小儿全麻诱导期胃进气的临床应用

目的：探讨超声在小儿全麻诱导期面罩通气阶段对胃进气实时监测的临床价值。方法：随机选取全麻下行择期手术的男性患儿54例，年龄2～4岁，按压力控制（PCV）模式下气道峰压（PIP）设定值随机分为3组（n=18）：P8组（PIP 8 cmH2O）、P12组（PIP 12 cmH2O）、P16组（PIP 16 cmH2O）。全麻诱导后行面罩正压通气120 s，测量通气前后超声下胃窦横截面积（CSA），并记录通气后30、60、90及120 s的脉搏氧饱和度（SpO2）、潮气量（Vt）、呼气末二氧化碳分压（PETCO2）与呼气末氧浓度（ETO2）。结果：面罩通气120 s后，共24例患儿发生胃内误进气（占45.3%），P12组与P16组患儿胃窦CSA显著增加。P8组患儿Vt显著低于其他2组，且通气量过低（＜6 mL/kg）患儿比率较高（占66.6%）。面罩通气120 s后，P8组患儿产生一定程度的二氧化碳蓄积[PETCO2=（40.6±4.0）mmHg]，P16组患儿则表现为过度通气[PETCO2=（23.6±1.4）mmHg]；P8组患儿ETO2显著低于另2组，P12组与P16组间差异无统计学意义。结论：超声实时监测利于及时发现小儿全麻诱导期面罩通气阶段胃内误进气，且PCV模式下PIP设定为12 cmH2O时，既可保证高质量预充氧，又可避免过度胃进气。

Clinical application of ultrasonography in monitoring gastric insufflation in children during induction of general anesthesia

Objective: To investigate the clinical value of ultrasonography in monitoring gastric insufflation related to facemask ventilation in pediatric patients during induction of general anesthesia. Methods: Fifty-four 2-4 years old male children received elective surgery under general anesthesia were randomized to 3 groups (P8, P12, and P16) defined by the PIP applied during PCV mode: 8, 12, and 16 cmH2O. Anesthesia was induced using fentanil, propofol and rocuronium in sequence. Once loss of eyelash reflex occurred, facemask pressure-controlled ventilation was started for a 120 s period while gastric insufflation was detected by real-time ultrasonographic monitoring. The antral cross-sectional area (CSA) was measured using ultrasonography before and after facemask ventilation. The noninvasive respiratory parameters were recorded at time 30, 60, 90, and 120 s during facemask ventilation. Results: After facemask ventilation for 120 s, gastric insufflation was detected in 24 children (45.3%) by ultrasonographic monitoring, and the antral CSA was significantly increased in groups P12 and P16. The Vt (mL/kg) of group P8 was significantly lower than the other two groups, and the probability of hypoventilation (Vt<6 mL/kg) was high which was 66.6%. After 120 s facemask ventilation, group P8 showed a certain CO2 accumulation for PETCO2 at (40.6±4.0) mmHg. Contrarily, group P16 showed excessive ventilation for PETCO2 at (23.6±1.4) mmHg. At the same time, the ETO2 of group P8 was lower than in groups P12 and P16 which had no significant difference. Conclusion: Ultrasonography can be well used in monitoring gastric insufflation related to facemask ventilation during induction of anesthesia. When PIP value is set as 12 mmHg, there was low incidence of gastric insufflation with adequate pulmonary ventilation in 2-4 years children.