目的 针对腹腔镜术后肺功能损害的高发人群肥胖患者，从预防气压伤角度研究机械通气时多呼吸参数（三因素三水平）的组合选用，以求减小或避免多呼吸参数的不当组合引起的较高气道压，从而获得“较低气道压力同时又能维持良好通气”的肺保护效应,以完善肥胖患者腹腔镜术后呼吸功能障碍的预防措施。方法 按公认的“30≤BMI<40”肥胖指数筛选ASAⅠ~Ⅱ肥胖患者,随机作为样本病例；取麻醉机上最基本的呼吸频率（f）、潮气量（VT）、吸呼比（I∶E）三参数作为三因素A、B、C，取f=15、12、9次/min，VT=8、10、12 mL/kg，I∶E=1∶2.5、1∶2.0、1∶1.5为相应的三水平；选用L9(34)K=3重复正交试验设计表归纳数据，检验、分析各因素及水平变化影响呼末二氧化碳分压（P_ETCO₂）、气道峰压（PIP）、气道平均压（P_mean）和内源性呼末气道压（PEEPi）的统计学意义。采用方差分析方法分析数据。结果 本研究9组试验的（k=3，n=27）腹腔镜手术全麻中，患者生命体征平稳，SpO₂ 100%。整个实验过程中PEEPi监测值为3 cmH₂O。三因素三水平呼吸参数间的不同组合对P_ETCO₂、PIP、Pmean的影响如下：①对P_ETCO₂的影响：f、VT各水平的选用均有显著统计学意义（P<0.01）；I∶E的选用无统计学意义（P>0.05）。②对PIP的影响：f的改变有统计学意义（0.01<P<0.05）；VT、I∶E的改变均有显著统计学意义（P<0.01）。③对P_mean的影响，三因素三水平呼吸参数的选用均有显著统计学意义（P<0.01）。结论 多呼吸参数的最佳组合方式是A3B1C2，即f=9次/min、VT=8 mL/kg、I∶E=1∶2.0，非小潮气量快频率，也非大潮气量慢频率。如此才能获得肥胖患者全麻气腹状态“较低气道压力同时又能维持良好通气”的肺保护效应。值得注意的是：①I∶E对气道压（PIP、P_mean）的影响，即对肺保护的影响有着重要意义；②I∶E对PIP和P_mean的影响具有相向性。

Objective Pulmonary dysfunction is common in the obese patients after laparoscopic surgery. To reduce or avoid this complication caused by improper combination of mechanical ventilatory parameters,we conducted the following trial of 3 factors with 3 levels of mechanical ventilation in order to explore the optimal combination with low airway pressure. Methods Patients were randomly allocated into 9 groups (k=3, n=27) according to the “30≤BMI<40” obesity index (ASAⅠ-Ⅱ). Anesthesia machine parameters were set as follows: respiratory frequency (f), tidal volume (VT), respiratory ratio (I∶E) as the three factors of A, B, C, with 3 levels of f=15, 12, 9 (bpm), VT=8, 10, 12 (mL/kg), I∶E=1∶2.5, 1∶2.0, 1∶1.5. By using L9(34)K=3 repeat orthogonal experimental design and analysis table, the variable factors that affect the respiratory index such as the end tidal carbon dioxide pressure (P_ETCO₂), peak airway pressure (PIP), mean airway pressure (P_mean), and the end of endogenous airway pressure (PEEPi) were analyzed.ResultsIn this study, 27 cases undergoing laparoscopic surgery under general anesthesia were allocated into 9 experimental groups. The hemodynamics of these patients was stable, SpO₂ was kept at 100 percent during the operation. The results of different combinations were described as follows: ①P_ETCO₂: f and VT with different level had great impact on P_ETCO₂ (P<0.01), I∶E had no significant difference in three levels (P>0.05); ② PIP: f had great effect on PIP (P<0.05); VT and I∶E in three levels also had significant effect on PIP (P<0.01); ③ P_mean: all the ventilation parameters with different combination had significant effect on P_mean (P<0.01). Conclusions The best combination of respiratory parameters is A3B1C2, i.e., f=9 bpm, VT=8 mL/kg, and I∶E=1∶2.0, which indicates that neither small tidal volume and faster frequency, nor slow frequency large tidal volume is a good choice. In order to let obese patients under general anesthesia obtain the best lung protective effect by low airway pressure with good ventilation, it is worth noting that: ①I∶E has a great effect on airway pressure (PIP, P_mean), which is important for lung protection; ②I∶E has the opposite effect on PIP and P_mean.