Libert Nicolas, Harrois Anatole, Baudry Nathalie, Vicaut Eric, Duranteau Jacques
From the Laboratoire d'Etude de la Microcirculation (N.L., N.B.), Université Paris 7, Hôpitaux Saint Louis Lariboisière, Assistance Publique-Hôpitaux de Paris, Paris; Service d'Anesthésie-Réanimation (N.L.), Hopital d'Instruction des Armées Percy, Clamart; Service d'Anesthésie-Réanimation Chirurgicale (A.H., J.D.), Hôpital de Bicêtre, Université Paris-Sud, Hôpitaux Universitaires Paris-Sud, Assistance Publique-Hôpitaux de Paris, Le Kremlin Bicêtre; and Unité de Recherche Clinique (E.V.), Université Paris 7, Hôpitaux Saint Louis Lariboisière, Assistance Publique-Hôpitaux de Paris, Paris, France.
J Trauma Acute Care Surg. 2017 Sep;83(3):476-484. doi: 10.1097/TA.0000000000001573.
Hypotensive resuscitation is the standard of care of hemorrhagic shock resuscitation. The optimal level of arterial pressure is debated and there is a lack of data on relationships between arterial pressure, microcirculation and tissue oxygenation. We investigated the relationship between mean arterial pressure, intestinal microcirculation and mucosal oxygen tension during hemorrhagic shock and resuscitation at different inspired oxygen fraction concentration.
The study was divided into two phases: 32 mice were progressively exsanguinated and then transfused in mean arterial pressure (MAP)-titrated steps of 10 mm Hg. Mice were randomized to four experimental groups: a control group in which sham mice underwent a laparotomy and three interventional groups with a common phase of exsanguination followed by progressive resuscitation at three different inspired oxygen concentrations (FIO2) (15%, 30%, and 100%). Intestinal mucosal oxygenation (intestinal PO2) and microcirculatory parameters were recorded at each 10 mm Hg MAP step.
During exsanguination, intestinal PO2 decreased linearly with MAP levels. Microcirculatory parameters decreased nonlinearly with MAP levels while they had a linear relationship with intestinal PO2. Intestinal mucosal hypoxia (PO2 ≤ 20 mm Hg) began at a MAP of 60 mm Hg and MAP < 60 mm Hg was associated with a high percentage of animal with intestinal hypoxia (≥32%). Combination of MAP and microcirculatory parameters was superior to MAP alone at predicting mucosal oxygenation. Inversely, during resuscitation with FIO2 = 30%, the microcirculatory parameters increased linearly with MAP levels while they had a nonlinear relationship with intestinal PO2. Hypoxia (FIO2 = 15%) was poorly tolerated. In hyperoxic group (FIO2 = 100%) intestinal PO2 became significantly higher than baseline values as soon as 50 mm Hg MAP.
During hemorrhagic shock, intestinal PO2 decreased linearly with MAP levels and microcirculatory parameters. Associating MAP and microcirculatory parameters allowed a better prediction of intestinal PO2 than MAP alone. A MAP < 60 mm Hg was associated with a high percentage of animal with intestinal hypoxia. Normoxic resuscitation (FIO2 = 30%) was sufficient to restore intestinal PO2.
低血压复苏是失血性休克复苏的治疗标准。动脉压的最佳水平存在争议，且缺乏关于动脉压、微循环和组织氧合之间关系的数据。我们研究了在不同吸入氧分数浓度下失血性休克及复苏过程中平均动脉压、肠道微循环和黏膜氧分压之间的关系。
本研究分为两个阶段：32只小鼠逐步放血，然后以10 mmHg的平均动脉压（MAP）滴定步骤进行输血。小鼠被随机分为四个实验组：一个对照组，假手术小鼠接受剖腹手术；三个干预组，有一个共同的放血阶段，随后在三种不同的吸入氧浓度（FIO2）（15%、30%和100%）下进行逐步复苏。在每个10 mmHg MAP步骤记录肠道黏膜氧合（肠道PO2）和微循环参数。
放血期间，肠道PO2随MAP水平呈线性下降。微循环参数随MAP水平呈非线性下降，而它们与肠道PO2呈线性关系。肠道黏膜缺氧（PO2≤20 mmHg）始于MAP为60 mmHg时，MAP<60 mmHg与高比例的肠道缺氧动物（≥32%）相关。MAP和微循环参数的组合在预测黏膜氧合方面优于单独的MAP。相反，在FIO2 = 30%复苏期间，微循环参数随MAP水平呈线性增加，而它们与肠道PO2呈非线性关系。低氧（FIO2 = 15%）耐受性差。在高氧组（FIO2 = 100%），一旦MAP达到50 mmHg，肠道PO2就显著高于基线值。
在失血性休克期间，肠道PO2随MAP水平和微循环参数呈线性下降。将MAP和微循环参数结合起来比单独使用MAP能更好地预测肠道PO2。MAP<60 mmHg与高比例的肠道缺氧动物相关。常氧复苏（FIO2 = 30%）足以恢复肠道PO2。
