Herff Holger, Paal Peter, von Goedecke Achim, Lindner Karl H, Severing Anette C, Wenzel Volker
Department of Anesthesiology and Critical Care Medicine, Innsbruck Medical University Innsbruck, Austria.
Crit Care Med. 2008 Sep;36(9):2613-20. doi: 10.1097/CCM.0b013e31818477f0.
To investigate the effect of different ventilation settings on hemodynamic stability in severe controlled hemorrhagic shock.
Prospective, randomized, controlled animal study.
Research laboratory in a university hospital.
Approximately 35-45 kg domestic pigs.
Twenty-four domestic pigs were bled 45 mL/kg (estimated 65% of their calculated blood volume) and then ventilated with either 0 cm H2O positive end-expiratory pressure and a respiratory rate of 14 ventilations/min (positive end-expiratory pressure 0 respiratory rate 14), or with 5 cm H2O positive end-expiratory pressure, a respiratory rate of 28 ventilations/min, and a tidal volume reduced by half (positive end-expiratory pressure 5 respiratory rate 28), or with 5 cm H2O positive end-expiratory pressure and a respiratory rate of 14 ventilations/min (positive end-expiratory pressure 5 respiratory rate 14). After 1 hr study phase surviving animals, received fluid resuscitation and were monitored for further 1 hr.
Pulmonary variables, hemodynamic variables, and short-term survival. There were no significant differences in mean arterial blood pressure and cardiac index after hemorrhage. After 20 mins of different ventilation strategies mean arterial blood pressure was 40 +/- 3 mm Hg in the positive end-expiratory pressure 0 respiratory rate 14 group, vs. 24 +/- 6 mm Hg the positive end-expiratory pressure 5 respiratory rate 28 group (p < 0.05) vs. 19 +/- 3 mm Hg in the positive end-expiratory pressure 5 respiratory rate 14 group (p < 0.01). Cardiac index was 65 +/- 5 mL/min/kg in the positive end-expiratory pressure 0 respiratory rate 14 group vs. 37 +/- 5 mL/min/kg in the positive end-expiratory pressure 5 respiratory rate 28 group(p < 0.01) and 20 +/- 3 mL/min/kg in the positive end-expiratory pressure 5 respiratory rate 14 group (p < 0.01). Mean airway pressure and positive end-expiratory pressure correlated strongly with mean arterial blood pressure and cardiac index. None of the positive end-expiratory pressure 0 respiratory rate 14 animals died in the study phase, whereas six of seven positive end-expiratory pressure 5 respiratory rate 28 animals, and all seven positive end-expiratory pressure 5 respiratory rate 14 animals died.
In this porcine model of severe hemorrhagic shock, reduction of positive end-expiratory pressure was the most important ventilation strategy component influencing hemodynamic stability. Reducing mean airway pressure by decreasing tidal volumes and increasing respiratory rates seemed to have less influence on cardiopulmonary function and survival than 0 cm H2O positive end-expiratory pressure.
探讨不同通气设置对严重控制性失血性休克血流动力学稳定性的影响。
前瞻性、随机、对照动物研究。
大学医院的研究实验室。
体重约35 - 45千克的家猪。
24只家猪放血45毫升/千克（约为其计算血容量的65%），然后分别以呼气末正压0厘米水柱、呼吸频率14次/分钟进行通气（呼气末正压0呼吸频率14），或以呼气末正压5厘米水柱、呼吸频率28次/分钟、潮气量减半进行通气（呼气末正压5呼吸频率28），或以呼气末正压5厘米水柱、呼吸频率14次/分钟进行通气（呼气末正压5呼吸频率14）。在1小时的研究阶段后，存活的动物接受液体复苏，并进一步监测1小时。
肺变量、血流动力学变量和短期生存率。出血后平均动脉血压和心脏指数无显著差异。在不同通气策略实施20分钟后，呼气末正压0呼吸频率14组的平均动脉血压为40±3毫米汞柱，呼气末正压5呼吸频率28组为24±6毫米汞柱（p<0.05），呼气末正压5呼吸频率14组为19±3毫米汞柱（p<0.01）。呼气末正压0呼吸频率14组的心脏指数为65±5毫升/分钟/千克，呼气末正压5呼吸频率28组为37±5毫升/分钟/千克（p<0.01），呼气末正压5呼吸频率14组为20±3毫升/分钟/千克（p<0.01）。平均气道压和呼气末正压与平均动脉血压和心脏指数密切相关。呼气末正压0呼吸频率14组在研究阶段无动物死亡，而呼气末正压5呼吸频率28组的7只动物中有6只死亡，呼气末正压5呼吸频率14组的7只动物全部死亡。
在这种严重失血性休克的猪模型中，降低呼气末正压是影响血流动力学稳定性的最重要通气策略组成部分。通过减少潮气量和增加呼吸频率来降低平均气道压，对心肺功能和生存率的影响似乎小于呼气末正压0厘米水柱。
