Martin Grace E, Johnson Mark, Veile Rose, Friend Lou Ann, Elterman Joel B, Johannigman Jay A, Pritts Timothy A, Goodman Michael D, Makley Amy T
Department of Surgery, College of Medicine, University of Cincinnati, Section of General Surgery, OH.
Department of Surgery, Institute for Military Medicine, University of Cincinnati, 231 Albert Sabin Way, Cincinnati, OH.
Mil Med. 2019 Oct 1;184(9-10):e460-e467. doi: 10.1093/milmed/usz034.
While damage control surgery and resuscitation techniques have revolutionized the care of injured service members who sustain severe traumatic hemorrhage, the physiologic and inflammatory consequences of hemostatic resuscitation and staged abdominal surgery in the face of early aeromedical evacuation (AE) have not been investigated. We hypothesized that post-injury AE with an open abdomen would have significant physiologic and inflammatory consequences compared to AE with a closed abdomen.
Evaluation of resuscitation and staged abdominal closure was performed using a murine model of hemorrhagic shock with laparotomy. Mice underwent controlled hemorrhage to a systolic blood pressure of 25 mmHg and received either no resuscitation, blood product resuscitation, or Hextend resuscitation to a systolic blood pressure of either 50 mmHg (partial resuscitation) or 80 mmHg (complete resuscitation). Laparotomies were either closed prior to AE (closed abdomens) or left open during AE (open abdomens) and subsequently closed. AE was simulated with a 1-hour exposure to a hypobaric hypoxic environment at 8,000 feet altitude. Mice were euthanized at 0, 4, or 24 hours following AE. Serum was collected and analyzed for physiologic variables and inflammatory cytokine levels. Samples of lung and small intestine were collected for tissue cytokine and myeloperoxidase analysis as indicators of intestinal inflammation. Survival curves were also performed.
Unresuscitated mice sustained an 85% mortality rate from hemorrhage and laparotomy, limiting the assessment of the effect of simulated AE in these subgroups. Overall survival was similar among all resuscitated groups regardless of the presence of hypobaric hypoxia, type of resuscitation, or abdominal closure status. Simulated AE had no observed effects on acid/base imbalance or the inflammatory response as compared to ground level controls. All mice experienced both metabolic acidosis and an acute inflammatory response after hemorrhage and injury, represented by an initial increase in serum interleukin (IL)-6 levels. Furthermore, mice with open abdomens had an elevated inflammatory response with increased levels of serum IL-10, serum tumor necrosis factor alpha, intestinal IL-6, intestinal IL-10, and pulmonary myeloperoxidase.
These results demonstrate the complex interaction of AE and temporary or definitive abdominal closure after post-injury laparotomy. Contrary to our hypothesis, we found that AE in those animals with open abdomens is relatively safe with no difference in mortality compared to those with closed abdomens. However, given the physiologic and inflammatory changes observed in animals with open abdomens, further evaluation is necessary prior to definitive recommendations regarding the safety or downstream effects of exposure to AE prior to definitive abdominal closure.
虽然损伤控制手术和复苏技术彻底改变了对遭受严重创伤性出血的受伤军人的护理，但面对早期航空医疗后送（AE）时，止血复苏和分期腹部手术的生理和炎症后果尚未得到研究。我们假设，与腹部闭合的AE相比，腹部开放的伤后AE会产生显著的生理和炎症后果。
使用剖腹术的失血性休克小鼠模型对复苏和分期腹部闭合进行评估。小鼠控制性出血至收缩压为25 mmHg，然后不进行复苏、接受血液制品复苏或贺斯（Hextend）复苏，使收缩压达到50 mmHg（部分复苏）或80 mmHg（完全复苏）。剖腹术在AE之前闭合（腹部闭合）或在AE期间保持开放（腹部开放），随后再闭合。通过在8000英尺高度暴露于低压低氧环境1小时来模拟AE。在AE后的0、4或24小时对小鼠实施安乐死。收集血清并分析生理变量和炎症细胞因子水平。收集肺和小肠样本进行组织细胞因子和髓过氧化物酶分析，作为肠道炎症的指标。还绘制了生存曲线。
未复苏的小鼠因出血和剖腹术死亡率达85%，限制了对这些亚组中模拟AE效果的评估。无论是否存在低压低氧、复苏类型或腹部闭合状态，所有复苏组的总体生存率相似。与地面水平对照相比，模拟AE对酸碱失衡或炎症反应未观察到影响。所有小鼠在出血和受伤后均出现代谢性酸中毒和急性炎症反应，表现为血清白细胞介素（IL）-6水平最初升高。此外，腹部开放的小鼠炎症反应增强，血清IL-10、血清肿瘤坏死因子α、肠道IL-6、肠道IL-10和肺髓过氧化物酶水平升高。
这些结果证明了伤后剖腹术后AE与临时或确定性腹部闭合之间的复杂相互作用。与我们的假设相反，我们发现腹部开放的动物中的AE相对安全，与腹部闭合的动物相比死亡率无差异。然而，鉴于在腹部开放的动物中观察到的生理和炎症变化，在就确定性腹部闭合前暴露于AE的安全性或下游效应做出明确建议之前，有必要进行进一步评估。
