Department of Surgery, University of Auckland, Auckland, New Zealand.
Applied Surgery and Metabolism Laboratory, School of Biological Sciences, University of Auckland, New Zealand.
J Anat. 2018 Jul;233(1):1-14. doi: 10.1111/joa.12811. Epub 2018 Apr 10.
The thoracic duct (TD) transports lymph drained from the body to the venous system in the neck via the lymphovenous junction. There has been increased interest in the TD lymph (including gut lymph) because of its putative role in the promotion of systemic inflammation and organ dysfunction during acute and critical illness. Minimally invasive TD cannulation has recently been described as a potential method to access TD lymph for investigation. However, marked anatomical variability exists in the terminal segment and the physiology regarding the ostial valve and terminal TD is poorly understood. A systematic review was conducted using three databases from 1909 until May 2017. Human and animal studies were included and data from surgical, radiological and cadaveric studies were retrieved. Sixty-three articles from the last 108 years were included in the analysis. The terminal TD exists as a single duct in its terminal course in 72% of cases and 13% have multiple terminations: double (8.5%), triple (1.8%) and quadruple (2.2%). The ostial valve functions to regulate flow in relation to the respiratory cycle. The patency of this valve found at the lymphovenous junction opening, is determined by venous wall tension. During inspiration, central venous pressure (CVP) falls and the valve cusps collapse to allow antegrade flow of lymph into the vein. During early expiration when CVP and venous wall tension rises, the ostial valve leaflets cover the opening of the lymphovenous junction preventing antegrade lymph flow. During chronic disease states associated with an elevated mean CVP (e.g. in heart failure or cirrhosis), there is a limitation of flow across the lymphovenous junction. Although lymph production is increased in both heart failure and cirrhosis, TD lymph outflow across the lymphovenous junction is unable to compensate for this increase. In conclusion the terminal TD shows marked anatomical variability and TD lymph flow is controlled at the ostial valve, which responds to changes in CVP. This information is relevant to techniques for cannulating the TD, with the aid of minimally invasive methods and high resolution ultrasonography, to enable longitudinal physiology and lymph composition studies in awake patients with both acute and chronic disease.
胸导管（TD）将身体排出的淋巴液通过淋巴静脉交界处输送到颈部的静脉系统。由于 TD 淋巴（包括肠道淋巴）在急性和危重病期间促进全身炎症和器官功能障碍方面的潜在作用，人们对其兴趣日益增加。最近，微创 TD 插管被描述为一种获取 TD 淋巴以进行研究的潜在方法。然而，终端段的解剖结构存在明显的变异性，关于口瓣膜和终端 TD 的生理学知识还知之甚少。从 1909 年到 2017 年 5 月，使用三个数据库进行了系统评价。纳入了人类和动物研究，并检索了来自外科、放射学和尸体研究的数据。在过去的 108 年中，有 63 篇文章被纳入分析。在 72%的情况下，终端 TD 在其终末过程中存在单个导管，而 13%有多个终末：双（8.5%）、三（1.8%）和四（2.2%）。口瓣膜的功能是根据呼吸周期调节流量。在淋巴静脉交界处开口处发现的这个瓣膜的通畅性，由静脉壁张力决定。吸气时，中心静脉压（CVP）下降，瓣膜瓣叶塌陷，允许淋巴向前流入静脉。在早期呼气时，当 CVP 和静脉壁张力升高时，口瓣膜瓣叶覆盖淋巴管交界处的开口，防止淋巴向前流动。在与平均 CVP 升高相关的慢性疾病状态下（例如心力衰竭或肝硬化），淋巴静脉交界处的流量受到限制。尽管心力衰竭和肝硬化时淋巴生成增加，但 TD 淋巴流出通过淋巴静脉交界处仍无法补偿这种增加。总之，终端 TD 显示出明显的解剖结构变异性，TD 淋巴流动在口瓣膜处受到控制，口瓣膜对 CVP 的变化做出反应。这些信息与使用微创方法和高分辨率超声技术对 TD 进行插管的技术相关，以便在急性和慢性疾病患者清醒时进行纵向生理学和淋巴成分研究。
