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Chin Med J (Taipei) 1997;59:141-3.
Department of Orthopaedic Surgery, Chi-Mei Foundation Hospital, Tainan, Taiwan, R.O.C.
A case is reported of chylothorax following an uneventful anterior thoracic interbody spinal fusion. To present knowledge, this complication is reported to occur in 0.2% of intrathoracic operations, and may give rise to 50% mortality unless stress properly recognized and managed.
[Chin Med J (Taipei) 1997;59:141-3.]
Keywords: anterior spinal surgery, chylothorax
Received: May 9, 1996.
Accepted: November 7, 1996.
Address reprint requests to: Dr. Steven K. H. Huan, Department of Orthopaedic Surgery, Chi-Mei Foundation Hospital, No. 901, Chung Hwa Road, Yung Kang City, Tainan, Taiwan, R.O.C.
Anterior surgical approaches to the spine, popularized by Hodgson and Stock in the 1960s, are now commonly used for the treatment of spinal deformities [1]. Although numerous postoperative complications have been reported, chylothorax is an unusual morbidity for this procedure. Chylothorax is an accumulation of fluid, rich in triglycerides and characterized by the presence of chylomicrons, in the pleural space. It is a rare complication resulting from an anterior approach for fusion of the thoracolumbar spine. This report concerns a patient who developed chylothorax following an anterior thoracic spine fusion.
A 72-year-old kyphotic female had been complaining of lower back pain for 2 years. Bilateral leg pain had attacked her in the past two weeks. Paraparesis, tightness and numbness in dermatomere of T12 were noted in a necrologic examination. Roentgenographic exam revealed several adjacent wedged vertebral bodies, from T6-T10, with 40 degree of kyphosis and compression fracture of T12 vertebral body. Nonunion of the fracture site and narrowing of the spinal canal from angulation at the T12 level were noted in the myelogram and computer tomography ( CT ) scan. A left thoracoabdominal approach was used, via the tenth rib space. Removal of T12 vertebral body, interbody fusion between T11 and L1 and fixation with anterior locking plate system (ALPS), were performed. During the procedure, there was no unusual finding except osteoporotic bone. A chest tube was inserted in the pleural cavity and a hemovac drain, in the retroperitoneal space.
Postoperatively, closed chest tube drainage was maintained for 3 days until the output was less than 50 c.c. per 24 hours. The color of the fluid from the chest tube was pink. The chest tube was removed on the fourth postoperative day when there had been no drainage for 24 hours. The fluid from the Hemovac was pink, and the amount was less than 50 c.c. daily after fourth postoperative day. The Hemovac was removed on the sixth postoperative day. No special complaint was noted: respiration pattern was good, no rales, no ronchi, and no dyspnea or tachypnea were noted during the postoperative period. Thus the roentgenographic exam was not repeated.
The patient was started on a liquid diet on the second postoperative day, progressing to a soft diet on the third day. After removal of the drain, there was no additional leakage from the wound or any noticeable symptoms. The patient was discharged on postoperative Day 10 without any symptom of dyspnea. Two days later, she came to this Emergency Room with the chief complaint of sudden onset of shortness of breath. A chest x-ray demonstrated a large left pleural effusion. Thoracentesis yielded 2,000 cc of milky fluid high in triglycerides, and a chest tube was then placed. Cytological evaluation revealed 400 mononuclear cell per mm3, but no bacteria and no neutrophils. Cyanosis with decrease of blood pressure then attacked her. Cardiopulmonary resuscitaion was performed, and intubation was administered. She was sent to the intensive care unit (ICU) with stable blood pressure and a coma scale of E1 VTM1, with incubation.
Under the diagnosis of chylothorax, the patient started on a complete enteral diet using medium chain triglycerides as the source of fats through nasogastric tube feeding Within a week, the output from the chest tube decreased substantially to 50 cc of serousfluid per day. But the patient had been suffering from persistent loss of consciousness, and pneumonia developed progressively in the right lower lobe. She finally expired from respiratory failure on postoperative Day 26.
Chyle is an odourless, sterile, bacteriostatic, alkaline, milk white and opaque fluid which transports ingested fats. Chyle flows cephalad via the union of the two lumbar lymphatic trunks and the intestinal trunk [2-4]. The lumbar lymphatic trunks form at the aortic bifurcation, and ascend on either side of the aorta to the L1-L2 level where they join to form the cisterna chyli behind the right diaphragmatic crus. The left lumbar trunk usually receives the draining from the intestinal lacterals and carries most of the chylous Nymph. Continuation of the cisterna chyli forms the thoracic duct in the posterior mediastinum. The thoracic duct carries lymph drainage from the abdominal area and the infradiaphragmatic portion of the body. Flow through the thoracic duct may increase to more than 200 c.c. per hour after a fatty meal. At the fifth thoracic vertebra, the thoracic duct crosses to the left and enters the superior mediastinum, where it terminates at the root of the neck by draining into the angle between the left subclavian and internal jugular veins [4]. Chylothorax is the extravasation and accumulation of chyle from the thoracic duct, or one of its major tributaries, into the pleural cavity. Injury to the thoracic duct at or below the fifth thoracic vertebra usually results in a right-sided chylothorax, whereas injury above the fifth thoracic vertebrae usually results in a left-sided chylothorax. Operative, nonoperative trauma, and neoplasms are the most common etiology. This condition has been reported by various authors following cardiac surgery, sympathectomy, esophagectomy, aneurysmectomy, and neck operations, but had rarely presented in the literature as a complication of anterior spinal surgery.
In this patient, care was taken to mobilize the cisterna chyli and no obvious presentation of white fluid was noted during operation. The postoperative period was also very smooth. However, the dyspnea attacked her on postoperative Day 12th under the impression of left-sided chylothorax. It is now believed that there was an injury to a small left-sided tributary of the thoracic duct, and chyle was able to leak through the recently sutured diaphragm into the pleural cavity, thus producing a chylothorax.
Chylous effusions are odourless, exudative, bacteriosfatic an lymphocytepredominant. The first clue to diagnosis of a chylothorax is recognition of the fluid aspirated from the chest or drained from the thoracestomy tube as chyle. The hallmark of chylous fluid is an elevated triglyceride level. If the triglyceride level is greater than 110 mg/dl, there is a 99% chance that the fluid is chyle. The presence of chylomicrons is also diagnostic. It is important to test amylase levels to rule out pancreatic injury [5]. Chylous effusions are nonirritating to the pleura and usually do not induce pleural peel formation Chylothorax is manifested by dyspnea and shortness of breath. Fulminating septicemia or superinfection is not common because chyle is bacteriostaffc fluid. Typically, clinical manifestations of chylothorax usually occur by Day 4 or 5 after resumption of a regular diet is resumed. There are several methods of localizing the source of a chylous leak. In the absence of a chest tube, ethiodized lymphoangiography or nuclear lymphoangiography with technetium-antimony colloid may show the site of leakage.
The initial treatment of chylothorax is dietary manipulation with administration of medium-chain triglycerides (MCTs), which are absorbed directly into the portal venous system, as a source of fat. This therapy decreases flow in the thoracic duct by 70 to 80%, allowing the damaged lymphatic channels to seal [6-8]. Decompression of the involved chest with repeat thoracentesis or with a chest tube is necessary. Of average chylous output is greater than 1500 c.c. per day for more than five days in adults or greater than 100 c.c. per year of age per day for more than five days in children, or chylous flow has not significantly decreased after two to three weeks of dietary or total parenteral nutrition therapy, or metabolic or nutritional complications occur, surgical ligation of either the leaking tributary or the thoracic duct is usually indicated [6]. Procedures most likely to control the lymphatic leak in primary chylothorax include direct closure of the leaking lymphatic channel, ligation of the thoracic duct at the diaphragm with closure of the leaking mediastinal pleura and mass ligature of the tissue found between the azygos vein and the aorta.
Proper management will depend on the initial nutritional state of the patient, the cause and severity of the chylothorax and, in rare instances, the anatomy of the thoracic duct. Familiarity with therapeutic options, along with appropriate timing for surgical intervention, is required to prevent complications of malnutrition and infection from persistent loss of chyle when other modes of therapy have failed [6].
Patients undergoing anterior spine surgery, especially in the thoracolumbar area, appear to be at risk for the development of postoperative chylothorax. While performing an anterior surgical approach to the spine, the orthopedic surgeon must be aware of the anatomy of the prevertebral lymphatics and of the possibility of damage and consequent leakage of chyle. To prescribe a postoperative roentgenographic exam is important; this should not be ignored, even with a normal physical examination of respiration. Although this report describes the experience of just one case who finally expired due to this complication, it is hoped it will help others who may encountering this lifethreatening condition.
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Copyright: 1997, Chinese Medical Association (Taipei)