Malbrain M L N G, Pelosi P, De laet I, Lattuada M, Hedenstierna G
ZiekenhuisNetwerk Antwerpen, Campus Stuivenberg, Intensive Care Unit, Antwerp, Belgium.
Acta Clin Belg. 2007;62 Suppl 1:152-61.
Patients with sepsis often receive large amounts of fluids and the presence of capillary leak, trauma or bleeding results in ongoing fluid resuscitation. This increases interstitial and intestinal edema and finally leads to intra-abdominal hypertension (IAH), which in turn impedes lymphatic drainage. Patients with IAH often develop secondary respiratory failure needing mechanical ventilation with high intrathoracic pressure or PEEP that might further alter lymphatic drainage. This review will try to convince the reader of the importance of the lymphatics in septic patients with IAH.
A Medline and PubMed literature search was performed using the terms "abdominal pressure", "lymphatic drainage" and "ascites formation". The references from these studies were searched for relevant articles that may have been missed in the primary search. These articles served as the basis for the recommendations below.
Induction of sepsis with lesion of the capillary alveolar barrier results in an increased water gradient between the capillaries and the interstitium in the lungs. The drainage flow to the thoracic duct is initially increased in order to protect the Lung and maintain the pulmonary interstitium as dry as possible, however this results in increased intrathoracic pressure. Sepsis also increases the permeability of the capillaries in the splanchnic beds. In analogy to the lungs the lymphatic flow in the splanchnic areas increases together with the pressure inside as a physiological response in order to limit the increase in IAP. At a critical IAP level (around 20 cmH2O) the lymph flow starts to decrease and the splanchnic water content progressively increases. The lymph flow from the abdomen to the thorax is progressively decreased resulting in increased splanchnic water content and ascites formation. The presence of mechanical ventilation with high PEEP reduces the lymph drainage further which together with the increase in IAP decreases the lymphatic pressure gradient in the splanchnic regions, with a further increase in water content and IAP triggering a vicious cycle.
Although often overlooked the role of lymphatic flow is complex but very important to determine not only the fluid balance in the lung but also in the peripheral organs. Different pathologies and treatments can markedly influence the pathophysiology of the lymphatics with dramatic effects on endorgan function.
脓毒症患者常接受大量液体治疗，而毛细血管渗漏、创伤或出血导致需要持续进行液体复苏。这会增加间质和肠道水肿，最终导致腹腔内高压（IAH），进而阻碍淋巴引流。IAH患者常继发呼吸衰竭，需要采用高胸内压或呼气末正压（PEEP）的机械通气，这可能会进一步改变淋巴引流。本综述旨在让读者相信淋巴系统在患有IAH的脓毒症患者中的重要性。
使用“腹腔压力”“淋巴引流”和“腹水形成”等术语在Medline和PubMed数据库中进行文献检索。对这些研究的参考文献进行搜索，以查找在初次检索中可能遗漏的相关文章。这些文章作为以下建议的基础。
毛细血管肺泡屏障受损引发脓毒症会导致肺毛细血管与间质之间的水梯度增加。为保护肺并尽可能保持肺间质干燥，最初流向胸导管的引流流量会增加，但这会导致胸内压升高。脓毒症还会增加内脏床毛细血管的通透性。与肺部情况类似，内脏区域的淋巴流量会随着内部压力的增加而增加，这是一种生理反应，目的是限制腹腔内压（IAP）的升高。在临界IAP水平（约20 cmH₂O）时，淋巴流量开始减少，内脏含水量逐渐增加。从腹部到胸部的淋巴流量逐渐减少，导致内脏含水量增加和腹水形成。高PEEP机械通气的存在会进一步减少淋巴引流，这与IAP升高一起降低了内脏区域的淋巴压力梯度，导致含水量和IAP进一步升高，从而引发恶性循环。
尽管淋巴引流的作用常常被忽视，但其作用复杂，不仅对于确定肺部的液体平衡，而且对于确定外周器官的液体平衡都非常重要。不同的病理状况和治疗方法会显著影响淋巴系统的病理生理学，对终末器官功能产生重大影响。
