呼气末正压对急性呼吸窘迫综合征绵羊内脏器官灌注的影响

目的　观察呼气末正压 (PEEP)对急性呼吸窘迫综合征 (ARDS)绵羊内脏器官灌注的影响。方法　内毒素 (LPS)静脉注射复制绵羊ARDS模型 ,维持心脏最佳前负荷 ,依次调整PEEP为 5、 10、15cmH2 O ,观察不同PEEP对血流动力学、呼吸力学、氧代谢及内脏器官灌注的影响。结果　与基础值(PEEP =0cmH2 O)比较 ,PEEP 5、 10、 15cmH2 O组心率、平均动脉压、肺动脉压、中心静脉压、肺动脉嵌顿压及心输出量差异无显著性意义 ,但PEEP 10、 15cmH2 0组动脉氧分压和动脉氧饱和度均同步明显增加 ,氧合指数也从 ( 10 4 6 4± 2 5 2 1)mmHg提高到 ( 136 2 5± 38 5 4 )和 ( 135 37± 37 5 6 )mmHg (P <0 0 5 ) ,PEEP 5、 10、 15cmH2 O组肠黏膜pH值 (pHi)与基础比较 ,差异无显著性意义 (P >0 0 5 )。各组肠黏膜与动脉二氧化碳分压差 (Pg aCO2 )也无明显差异。全身氧输送、血乳酸无明显改变 (P >0 0 5 )。与基础值比较 ,PEEP各组平均气道压、气道平台压及肺动态顺应性显著增加 ,PEEP 15cmH2 O组气道峰压也明显增高(P <0 0 5 )。结论　维持心脏最佳前负荷状态下 ,血流动力学和氧输送可保持稳定 ,PEEP在 15cmH2 O以下对ARDS绵羊内脏灌注无明显影响

Effect of positive end expiratory pressure on splanchnic perfusion in sheep with acute respiratory distresssyndrome

Objective To evaluate the effects of positive end-expiratory pressure (PEEP) on splanchnic perfusion in sheep with acute respiratory distress syndrome (ARDS).Methods Eighteen sheep with ARDS were induced by lipopolysaccharides. Each sheep received mechanical ventilation with different PEEP (0?5?10?15cmH 2O).Hemodynamics, oxygen metabolism, lung mechanics and mucosal pHi were measured at 2 h after mechanical ventilation with each different PEEP setting.Results Heart rate?mean arterial pressure?pulmonary arterial pressure?central venous pressure?pulmonary arterial wedge pressure and cardiac output had no significant differences in all groups.Compared with baseline values (PEEP 0 cmH 2O), partial pressure of arterial oxygen and saturation of arterial oxygen and oxygenation index increased significantly. Oxygen delivery index, lactate arid had no difference in all groups ( P >0 05),same as pHi. Plateau pressure, mean airway pressure and dynamic compliance with PEEP increased significantly, and peak inspiratory pressure rose markedlyin the group with PEEP 15 cmH 2O ( P <0 05).Conclusion PEEP lower than 15 cmH 2O did. not have effect on splanchnic perfusion when hemodynamic parameters were stable.