颈淋巴清扫术后乳糜瘘的处理

The present article is focused on the management of lymphatic, chylous, and thoracic duct lesions following head and neck surgery, with particular attention to these complications after neck dissection.

临床解剖

胸导管

在胸上部，胸导管开始于左锁骨下动脉第一段的后面，但是当它进入颈基部时则位于颈总动脉的后面。从食管和左胸膜
之间，左颈总动脉、迷走神经之后这样深的部位，胸导管开始向上，并向前和向外侧，因此它出现在左颈总动脉和锁骨下动脉之间。当它转向外侧时，它位于椎动脉和甲状颈干之前，其弯部位于锁骨下动脉平面之上，经过颈内静脉和前斜角肌之间，达到左颈内静脉和锁骨下静脉外侧交界处。在此处，胸导管位于锁骨下动脉之浅面。胸导管可向上弯曲到颈部再下降，也可不向上，也不高过终点的水平。Lissitzgn曾指出， 胸导管高且弯者发生在胸廓口窄的患者，胸导管低位则发生在胸廓口宽的患者。胸导管高者可达锁骨上5厘米。

胸导管末端注入左颈内静脉角者最多，占52.28 ％，终于左锁骨下静脉的次之，占 29 .55 ％，注入左颈内静脉者占6.82 ％ 。此外，尚可注入左头臂静脉或以二支分别汇入左 颈静脉角和左锁骨下静脉；或以二支分别汇入左颈静脉角和左颈内静脉。偶尔亦可注入 右颈静脉角。胸导管颈段多为一支，二支或三支者较少见。

右淋巴导管

右淋巴导管由右颈淋巴干、右锁骨下淋巴干和右支气管纵隔淋巴干汇合形成 。因此它接受右侧头颈部的淋巴、右上肢和右胸部的淋巴。三个淋巴干合为一个管道 再通入静脉的比较少，实际上它们分别通入静脉或形成不同的组合再通入静脉。它们通 入内静脉、锁骨下静脉或这两个静脉的相交处。

发生机率

颈部手术尤其是颈淋巴清扫术对淋巴导管和胸导管的损伤，可能导致手术后出现乳糜瘘(chylous fistula)、乳糜胸(chylothorax)、纵隔乳糜症(chylomediastinum)、乳糜性心包积液(chylopericardium)、淋巴囊肿(ymphocele)、持续性淋巴瘘(persistent lymphorrhea)以及继发性淋巴水肿(secondary lymphedema)等并发症。

有研究发现根治性颈淋巴清扫术后，乳糜瘘发生率大约是1-2.5%¹。乳糜胸的发生率在颈淋巴清扫术后的发生率大约为0.5-2%²。综合多个研究来看，头颈部肿瘤颈淋巴清扫术后导致淋巴导管和胸导管损伤并引起相关并发症的机率在0.62-6.2%不等³。乳糜瘘大多发生在左侧，放疗后以及双侧颈清的患者，术后并发症出现的机率会更高。
尽管这些并发症的发生机率并不高，但是严重的并发症有导致患者死亡的风险。

处理

就处理手段而言，目前主要包括保守治疗（非外科治疗）和外科治疗两类。由于并发症的发生机率低，目前的所有研究结果以及治疗手段推荐均来自分散的案例以及队列研究，缺乏大样本随机对照研究，所以目前对于这些并发症的处理还缺乏公认有效的标准化处理程式，所以本文仅是各种处理手段的总结，不对这些手段的有效性进行评价。

非外科治疗手段

营养治疗手段

从减少淋巴液和乳糜液的产生、补充患者丧失的液体及电解质以及防治发生营养不良的目的出发，通过营养调节和饮食控制来治疗乳糜瘘等并发症发生的的保守手段获得了广泛的认可。主要的手段包括低脂或无脂饮食、特殊配方的肠内营养、全肠外营养以及上述手段的综合使用。

一般来说，对于营养状况良好且口服耐受的患者，可以采用低脂或无脂饮食。对于无法耐受经口进食的患者，乳糜瘘引流量少于1L/天，那么特殊配方的胃肠营养可以作为选择：小于0.5L/天者可以采用低脂半要素配方；高于0.5L/天者需要采用全要素配方。全胃肠外营养推荐用于乳糜瘘引流量大于1L/天的患者，或者前述手段无法控制的患者。

另外一种目前尚有争议的营养元素是中链甘油三脂(Medium-chain triglycerides)，一般认为其优势在于可以吸收后直接通过血液进入肝脏，而不需要通过淋巴系统，所以不会增加乳糜液的产生。但是也有很多研究不支持这种看法^{4 5}。
采用营养手段和饮食控制进行保守的患者，需要密切监控其治疗反应及营养状态，保证蛋白质、必需脂肪酸、电解质、维生素以及微量元素等的摄入。

但是目前对于某个具体的患者需要采取何种合适的营养治疗手段，营养治疗手段可以使用的最长时间，低脂饮食中脂肪含量的可接受量是多少以及什么时候可以认为营养治疗手段无效应当使用外科手段介入等问题都尚未达成共识。

生长抑素及其类似物

生长抑素以及类似物奥曲肽可以通过内分泌和旁分泌通路的作用降低乳糜液的产生、抑制胃肠和胰腺的分泌、降低肝静脉压以及减少内脏血流量。大多数情况下生长抑素以及类似物都是用于乳糜瘘量比较小的情况，不过也有在乳糜瘘量比较大的情况下使用成功的报道⁶。

负压创面治疗技术

负压创面治疗技术(Negative-pressure wound therapy)是1997年开始应用于临床的一种相对较新的技术。负压的使用有助于皮瓣和下方组织的贴合、引流乳糜液以及炎性渗出物、减轻乳糜液对周围组织刺激产生的炎性反应等。但是使用的时候需要有足够的软组织包裹保护周围的大血管以及血管吻合口，避免引起大出血以及影响移植皮瓣血供。

其他

除了营养治疗和饮食控制、生长抑素及其类似物的应用以及负压创面治疗技术以外，其他保守处理措施还有卧床休息并采取床头抬高的体位以及加压绷带包扎。使用加压绷带包扎是需要注意避免影响组织血供，尤其是放疗后的组织。

外科治疗手段

正常人一天乳糜液的引流量大约有1.5-4L，所以对与乳糜瘘的患者，引流量大于1L/天则认为是引流量过高。以往认为常规经过两周的保守治疗以后，如果引流量没有明显减少或仍然较高，那么此时便是外科介入的时机。近期的一些研究责任何时需要外科介入还需要考虑导致乳糜瘘的原因，比如对于喉切除术后出现乳糜胸的患者，保守治疗5天无效则可以使用外科手段进行控制。

对于持续存在低引流量的患者何时可以安全地拔除引流管并恢复正常进食，目前也并没有一致的意见，旧的指南建议可以在乳糜液引流量降低到200-300ml/天时进行，但是大多数文献研究并没有遵循这一建议。另外也有建议在拔除引流管前进行脂肪饮食测试("fatty meal" test)，即及时脂肪饮食两天后引流量未增加且无乳糜液出现，那么可以考虑安全拔管，否则可以考虑外科手段干预。

胸导管栓塞术

The treatment consists of diagnostic pedal lymphangiography followed by transabdominal catheterization of the cysterna chyli or lumbar lymphatics with thoracic duct embolization (TDE) proximal to the chyle leak. In addition to the minimally invasive nature of the procedure, which results in the reduction of mortality and morbidity, the ability to identify the location of the chyle leak and variation in thoracic duct anatomy potentially improves the outcome.

However, pedal lymphangiography is both time-consuming and technically challenging, and remains a significant barrier to perform a TDE. For this reason,some researchers ⁷ studied the feasibility of ultrasound-guided intranodal lymphangiogram for TDE, concluding that by using intranodal lymphangiogram the thoracic duct may be more quickly visualized and catheterized for TDE, compared to using pedal lymphangiography.
There is however concern that significant blockage of flow in the thoracic duct may result in complications related to the redistribution of this flow, such as leg swelling and chylous ascites. Development of protein-losing enteropathy has also been demonstrated in experimental studies after thoracic duct ligation. Chronic diarrhea and lower-extremity swelling may be related to TDE, and should be part of the informed consent before the procedure.

治疗性淋巴造影

The treatment is carried out by using a contrast solution of l5 ml of lidocaine and 5 ml of methylene blue dye and lipiodol to occlude lymphatic leaks. Though several successful cases were reported, care must be taken by radiographers to monitor patients for anaphylaxis, and severe cardiopulmonary comorbidities may contraindicate such a procedure. This novel use of older techniques for the visualization of lymphatic pathways holds promise as a minimally invasive approach to treat lymph and chyle leaks.

胸导管结扎术

Thoracic duct ligation can be performed through an open thoracotomy, but, more recently, a thoracoscopic approach has been successfully used for the treatment of chyle fistulas. Usually, the thoracic duct is identified via a right-sided approach. Occlusion of the thoracic duct occurs by mass ligation of the tissue above the supra-diaphragmatic hiatus between the azygos vein and the aorta.

Thoracoscopic ligation can be very successful at stemming intractable chyle fistulas with minimal associated morbidity.

局部组织瓣覆盖

Damage to the thoracic duct can be difficult to identify intraoperatively, as the rate of chyle flow is estimated to be only a couple of drops per second.

To detect a chyle leak during surgery, a manual abdominal compression maneuver would allow visualization of the thoracic duct leak at the end of neck dissection involving level IV. An alternative method was to give the patient continuous positive pressure and place the patient in the Trendelenburg position. The first clue to the fact that leakage might have occurred may be a sticky feeling on the surgeon’s gloves.

If a leak is identified during surgery, it should be immediately sutured. During neck surgery, it is also recommended to perform coverage of the area with a locoregional myofascial flap such as the pectoralis major, or, if still present, the clavicular head of the sternocleidomastoid to occlude the leak. Postsurgical pressure dressings are not recommended in such cases, particularly when there are microvascular anastomoses, because of the risk of compromising the flap viability.

显微淋巴管-静脉吻合术

Depending on the specific clinical picture, the following types of surgical and microsurgical procedures can be performed to treat complications after lymph–chylous–thoracic duct injuries: identification of the sites(s) of chylo-lymphorrhea; chylothorax drainage; removal of lymphocele, chylous cysts, and chylomas; resection of lymphangiectasic– lymphangiodysplasic tissue if present; ‘spaced-out’ antigravitational ligatures of lymphatic–chylous vessels; use of carbon dioxide laser which, when applied at low power, has a welding effect on lymphatic vessels, as well as on many other tissues and blood vessels, up to 1mm in diameter; pleurodesis and decortication; pericardial ‘window’; and pleura–venous/pleura–peritoneal shunts.

In addition to the above procedures, derivative lymphatic–venous anastomosis (LVA) or reconstructive lymphatic–venous–lymphatic anastomosis microsurgery, when technically applicable, can be very effective, with functional repair of lymphatic–chylous leaks depending on the individual case^{8 9 10}.
Regarding the LVA technique, the operation consists of performing multiple lymphatic–venous microanastomoses. Healthy-appearing lymphatics found at the site of surgical incision are selected and directly introduced into the cut-end of a recipient vein (usually internal or external jugular vein) by a U-shaped stitch and then fixed by additional stitches between the vein border and the perilymphatic adipose tissue. Using blue dye, properly functioning lymph vessels are identified and the passage of blue-colored lymph into the vein segment, seen under the operating microscope, verifies the patency of the LVA when anastomoses are completed.

备注：解剖描述引自陈日亭著《颌面颈手术解剖》，处理方式部分引自文献Campisi, C. C., Boccardo, F., Piazza, C., & Campisi, C. (2013). Evolution of chylous fistula management after neck dissection. Current Opinion in Otolaryngology and Head and Neck Surgery, 21(2), 150-156以及屠规益等主编《颈淋巴结转移癌临床》