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目的评估在急性肺损伤(ALI)伴腹内高压(IAH)时不同的呼吸末正压(PEEP)对家猪呼吸系统及血流动力学的影响。方法将6只家猪进行麻醉、气管切开后接呼吸机辅助通气,采用容量控制通气,潮气量(VT)8 mL/kg,呼吸频率16次/min,吸入氧浓度(FiO2)0.40,PEEP 5 cm H2O。基础状态维持30 min后,先用稀盐酸法制造ALI模型,再通过自动控制气腹机腹腔内注入氮气复制20 mm Hg的IAH模型。6只家猪均在同一呼吸机参数下选择不同的PEEP水平(5、10、15、20 cm H2O)维持机械通气1 h,观察以上4种不同PEEP水平下的肺氧合、呼吸力学及血流动力学指标的变化。结果 PEEP15和PEEP20的PaO2/FiO2分别为(172±23)mm Hg和(200±34)mm Hg,明显高于PEEP5的(90±11)mm Hg和PEEP10的(102±10)mm Hg(P<0.05),而PEEP15与PEEP20之间差异无统计学意义(P>0.05)。PEEP15和PEEP20的胸壁顺应性(Ccw)分别为(76±15)mL/cm H2O和(85±14)mL/cm H2O,均明显高于PEEP5的(26±3)mL/cm H2O(P<0.05)。4组不同PEEP水平的肺顺应性(CL)比较差异均无统计学意义(P>0.05)。PEEP15和PEEP20的平台压(Pplat)分别为(36±2)cm H2O和(38±4)cm H2O,明显高于PEEP5的(30±3)cm H2O和PEEP10的(31±2)cm H2O(P<0.05),而PEEP15与PEEP20比较差异无统计学意义(P>0.05)。PEEP15和PEEP20的心率分别为(147±30)次/min和(160±30)次/min,均明显高于PEEP5(113±17)次/min(P<0.05),而PEEP15和PEEP20比较差异无统计学意义(P>0.05)。PEEP20的心排指数(CI)为(3.5±0.6)L·min-1·m-2,较PEEP5的(4.5±0.6)L·min-1·m-2明显下降(P<0.05),而PEEP5、PEEP10和PEEP15组间比较差异无统计学意义(P>0.05)。PEEP15和PEEP20的中心静脉压(CVP)分别为(17±2)mm Hg和(18±3)mm Hg,明显高于PEEP5的(12±2)mm Hg(P<0.05),而PEEP15和PEEP20比较差异无统计学意义(P>0.05)。平均动脉压(MAP)、系统性血管阻力指数(SVRI)、胸腔内血容量指数(ITBVI)、全舒张末期容积指数(GEDI)、肺血管通透性指数(PVPI)、血管外肺水指数(EVLWI)在以上4种不同PEEP水平的差异均无统计学意义(P>0.05)。结论 ALI伴IAH时可引起呼吸生理严重的不协调,但PEEP水平的逐渐增加可显著改善呼吸机能,且对血流动力学无显著影响。
Objective To assess the effects of different positive end-expiratory pressures (PEEP) on respiratory system and hemodynamics of domestic pigs during acute lung injury (ALI) with intra-abdominal hypertension (IAH). Methods Six domestic pigs were anesthetized. After tracheotomy, ventilator-assisted ventilation was used. Ventricular volume was used to control ventilation. Tidal volume (VT) was 8 mL / kg, respiratory rate was 16 breaths per minute, 5 cm H2O. After maintaining the basal state for 30 min, the ALI model was prepared by dilute hydrochloric acid method and then the 20 mm Hg IAH model was injected by intraperitoneal injection of pneumoperitoneum automatically. 6 pigs under the same ventilator parameters to choose different levels of PEEP (5,10,15,20 cm H2O) to maintain mechanical ventilation 1 h, observe the above four different PEEP levels of pulmonary oxygenation, respiratory mechanics and blood Changes in hydrodynamic indicators. Results The PaO2 / FiO2 values of PEEP15 and PEEP20 were (172 ± 23) mm Hg and (200 ± 34) mm Hg respectively, which were significantly higher than those of PEEP5 (90 ± 11) mm Hg and (102 ± 10) mm Hg <0.05), while there was no significant difference between PEEP15 and PEEP20 (P> 0.05). The Ccw of PEEP15 and PEEP20 were (76 ± 15) mL / cm H2O and (85 ± 14) mL / cm H2O, respectively, which were significantly higher than those of PEEP5 (26 ± 3) mL / cm H2O 0.05). There was no significant difference in lung compliance (CL) between the four PEEP groups (P> 0.05). The Pplat of PEEP15 and PEEP20 were (36 ± 2) cm H2O and (38 ± 4) cm H2O, respectively, which were significantly higher than those of PEEP15 (30 ± 3) cm H2O and PEEP10 (31 ± 2) cm H2O P <0.05), while there was no significant difference between PEEP15 and PEEP20 (P> 0.05). The heart rate of PEEP15 and PEEP20 were significantly higher than that of PEEP5 (113 ± 17) / min (P <0.05), while the heart rate of PEEP15 and PEEP20 were significantly higher than those of PEEP15 and PEEP20 (147 ± 30) / min and (160 ± 30) No statistical significance (P> 0.05). The MI of PEEP20 was (3.5 ± 0.6) L · min-1 · m-2, which was significantly lower than that of PEEP5 (4.5 ± 0.6) L · min-1 · m-2 There was no significant difference between PEEP5, PEEP10 and PEEP15 groups (P> 0.05). Central venous pressure (CVP) of PEEP15 and PEEP20 were (17 ± 2) mm Hg and (18 ± 3) mm Hg, respectively, which were significantly higher than those of PEEP5 (12 ± 2) mm Hg (P <0.05) The difference was not statistically significant (P> 0.05). MAP, SVRI, ITBVI, GEDI, PVPI, extra-pulmonary lung water index EVLWI) in the above four different levels of PEEP difference was not statistically significant (P> 0.05). Conclusions ALI with IAH can cause serious respiratory physiology uncoordination, but the gradual increase of PEEP level can significantly improve respiratory function, and have no significant effect on hemodynamics.