Abstract
OBJECTIVE To review the experience of iatrogenic chylothorax after pulmonary resections for lung cancer and to evaluate our treatment strategy.
METHODS From July 1997 through December 2003, a total of 1,546 patients underwent pulmonary resection (at least lobectomy) and systematic mediastinal lymph node dissection for lung cancer in our division. Sixteen patients had a postoperative chylothorax complication. All of these patients in this study were conservatively treated (closed drainage) with complete oral intake cessation and total parenteral nutrition.
RESULTS All patients had their condition cured with conservative treatment. The duration of the treatment was 6-21 days. The patients were given normal diet for a mean of 9.8 days after chylothorax diagnosis.
CONCLUSION If the correct treatment strategy is selected, most cases of chylothorax after pulmonary resection with systematic mediastinal lymph node dissection can be cured with a conservative strategy.
keywords
With the indication for lung cancer surgery and increasing common systematic lymph node dissection, there has been a marked rise in the incidence of iatrogenic postoperative chylothorax. Postoperative chylothorax has become a prevalent complication of thoracic operations. We analytically reviewed 16 cases of chylotho raxes in 1,546 lung cancer patients who underwent pneumonectomy (at least lobectomy and systematic lymph node dissection) in Tianjin Cancer Hospital from July 1997 to December 2003.
Materials and Methods
Clinical data
Among the 1,546 patients who underwent a resection for lung cancer, 16 cases resulted in postoperative chylothoraxes (incidence 1.03%). They were 11 males and 5 females with a median age of 58 (42~72) (Table 1).
Clinical symptoms
After operation (2~6 days), pleural drainage increased when the patients began to eat. The highest volume of drainage was above 2,100 ml/day. Chylothoraxes were observed in the early days (2-3 days post-operation) from an increase in drainage, while those found in the later days were from the change of the color of pleural effusion. Thirteen patients suffered from a fast heart rate (>100/minute); 1 developed atrial fibrillation; 5 felt a shortness of breath and only 1 patient had an apparent decrease in arterial oxygen pressure.
Clinical Data
Diagnosis
1) Milky drainage, or increase of thoracic drainage after operation; 2) Positive ethylether test. 3) Upon dying with Sudan III, limited scarlet fat granules could be seen in the drainage.
Therapy
1) Closed drainage. In our hospital thoracic tubes were usually maintained for 4~7 days to enable us to detect early symptoms. Hence, we did not need thoracentesis or redraining. 2) Based on free drainage, patients with lower than 400 ml/day of drainage were given a normal diet and close observation. 3) Patients with 400800 ml/day of drainage were given a low fat diet and partial parenteral nutrition (PPN). 4) Complete oral intake cessation and total parenteral nutrition (TPN) were applied for the patients with over 800 ml/day of drainage. The formation of the TPN liquid was completed by the following steps: we calculated the Basal Energy Expenditure (BEE) for the patients with the Harris Benedict formula, then calculated Metabolic Energy Expenditure (MEE) for recondition, and finally rectified the calorie and calorie nitrogen ratio by monitoring nitrogen balance. 5) Based on sufficient drainage, pleural adhesions could be treated in the thorax, with agents such as tetracycline, nocardia rubra cell wall skeleton preparation, carboplatin and mannatide, etc. Some patients developed hyperpyrexia or thoracic pain, etc. These responses usually would persist for 2 or 3 days after which they were treated accordingly.
Results
The 16 patients were cured by conservative treatment and discharged from the hospital. There was not a case of re-operation or death. In our department, the standard conditions for removal of the thoracic tubes are: less drainage than 100 ml/day for 3 consecutive days after a normal diet; X-rays show no obvious pleural effusion and full lung re-distension. The criteria of cure of a post-operative chylothorax are no obvious clinical symptoms after removal of the thoracic tubes, such as chest distress, breath holding and rapid heart rate etc.; normal diet in general; X-ray shows no pleural effusion. The conservative treatment used for this group of cases took 6~21 days, with an average of 9.8 days. All the patients were followed up and there was no obvious pleural fluid in the normal lateral chest films after 3 to 6 months.
DISCUSSION
Along with the enhancement of the size of resection circumscription, especially that of the systematic lymph node dissection, and emphasizing en bloc resection, the incidence of lung cancer post-operative chylothorax his risen.
The thoracic duct starts from the chyloststis near the 12th thoracic vertebra, then goes through the aortic hiatus of the diaphragm and along the front of the spine between the thoracic aorta and azygos vein, and enters the posterior mediastinum. When reaching the level of 5th thoracic vertebra, it crosses the left forefront of the spine, then goes up near the middle of the left subclavian artery and the left side of the esophagus, and finally reaches the neck root. Since varied pathways for the thoracic duct exist in as many as 50% of normal people, damage is apt to occur during surgery. All lymph fluid flows into the thoracic duct except that from the right part of the head, cervix and thorax, and from the right upper extremity and two lungs. The lymph fluid from these sites empties into the right main lymphatic channel. It is worthwhile to mention that there are extensive lymph vein ramus anastomoticus among various lymph vessels, between the thoracic duct and azygos vein, intercostals veins or lumbar veins.
Under normal circumstances, the thoracic duct sends about 1,500-2,500 ml/day of chyle fluid into the venous system. Its protein content is over 30 g/L, and its electrolyte constituents are similar to serum. A huge loss of the chyle fluid may result in severe malnutrition, especially hypoproteinemia. The chyle fluid has certain capability of bacteriostasis. During complete ingestion cessation, the flow of the chyle fluid is only 14 ml/h. The flow can reach higher than 100 ml/h after ingestion. In addition, the flow of chyle fluid is related to the responsivity caused by the stimulation of the cells of thoracic duct smooth muscle on the internal organs and cranial nerves. 5-HTA, norepinephrine, histamine, dopamine and acetylcholine may increase smooth muscle contraction and chyle fluid flow. Hunger, complete cessation of ingestion and using opium preparations may decrease the chyle fluid.
When the loss of chyle fluid is over 3 L/day, the body will lose a large quantity of fluid, electrolyte constituents, fat, protein and lymphocytes, and cause severe malnutrition and immune deficiency. Therefore, the patient’s quantity of chyle fluid, body weight, plasma-albumin, total protein, total lymphocyte count and electrolyte level should be monitored during drainage. The nutrition loss is to be amended according to needs. A fat free, high protein and high caloric diet can decrease the quantity of chyle fluid. Because intravenous medium-chain fatty acids are directly taken up by the portal system without going through the intestinal tract and lymphatic vessels, they can be used as the main source of lipid for the body. They will provide adquate nutrition and also allow a decrease in the speed of the chyle fluid flow so as to facilitate rapid healing of the orificium fistulae.
The initial treatment of the chylothorax was continuous intercostal tube drainage, so as to cut down the pleural cavity pressure. For postoperative chylothorax cases, the most significant principle is free drainage. Obstructed drainage could lead to obvious increased heart rate, chest distress, breath holding, etc., even hypoxia. Constant drainage can relieve the compression of chyle fluid on the lungs to enable the collapsed lung to inflate again and to block the cavitas pleuralis as well as to accurately survey the transudation of the volume of chyle fluid. In some cases, due to failure of lung reinflation caused by the formation of a fibrin film on the lung surface, surgical operation will be needed.
In previous reports, most sources suggested that surgical intervention should be undertaken based on the following principles: quantity of chyle fluid over 1,500 ml/day in adult cases; invalidity of conservative treatment after 2 weeks; appearance of acute malnutrition and drainage even though there is no large volume of pleural effusion. However, the timing of surgical intervention of post-operative chylothorax has always been disputable. Although it has become a trend that early thoracotomy be performed to ligate the thoracic duct when chylothorax appears after esophageal carcinoma resection, it is not the same with lung cancers. Some scholars suggest that chyle fluid would not easily taper off, but abruptly diminish or stop at a certain point, so the quantity of the chyle fluid drained is not a good indicator for timing of the surgery. Others hold to a conservative treatment and surveying for 3~4 weeks before taking surgical intervention. Still others believe that as long as the doctors strictly perform conservative measures with determination, patients that need surgery actually would not be many.
We propose that it is advisable to adopt conservative treatment for the patients of chylothorax after lung cancer resection for the following reasons:
1) In our hospital, patients with a postoperative chylothorax following lung cancer resection have been mostly recipients of right superior lobectomy. The position of carcinoma and the metastatic lymph nodes are concentrated in the right superior mediastinum and subcarinal, an area normally not in the course of the thoracic duct. The lymphatic vessels in the area are mostly branches of the thoracic duct.
2) There are numerous anatomical variations of branches of the thoracic duct which are likely to be injured by mistake during thoracotomy. The anatomy of the variations and branches is complicated. Once a postoperative chylothorax occurs, ligating all branches will be difficult during re-operation. This is one of the main reasons why a chylothorax still exits after ligating the duct in the re-operation.
3) We usually keep the thoracic tubes in place for 4-7 days after lung cancer surgery. During this period chyle fluid or increase of drainage fluid will appear in most chylothorax cases and this enables us to identify such patients early. Thanks to relatively free drainage, a fibrous membrane is not easily formed and will not affect the lung re-expansion. There have been no cases of re-operation due to failure of lung re-expansion.
4) Since the production of chyle fluid has close ties to the diet, the post-meal volume of the fluid can reach over 100 ml/h. A lean, high protein and high caloric diet can decrease chyle fluid discharge. Particularly noticeable is that the chyle fluid flow in the thoracic duct has been 14 ml/h during abrosia. Hence, we believe that if strict complete cessation of ingestion is adopted after an operation, the production of chyle fluid will not exceed 500 ml/day and that, on the whole, will not affect the reexpansion of the operated lung.
5) We believe that the cicatrization after breakage of the thoracic duct is not real epithelial healing of the duct. In most cases it was the closing down of the cavitas pleuralis caused by conglutination of the peripheral tissues. That is why the application of an intrathoracic injection of a conglutination agent has been used and abrupt decrease or termination of drainage occurred at a certain point. Therefore, the re-expansion of the operated lung largely determined the speed of cicatrisation of the damaged thoracic duct.
6) Total parenteral nutrition support plays an important role in post operation chylothorax treatment. In the first place, one essential factor affecting the recovery of the chylothorax patient is the loss of fluid, electrolyte, fat, protein and lymphocytes that leads to severe malnutrition and immune defect. For patients who need strict fasting, the application of TPN solves their nutritional problem. The TPN can decrease the secretion of gastrointestinal tract digestive juice. We presume that it could also decrease chyle fluid though more empirical study it still needed to confirm this assumption.
In summary, the choice of treatment of a chylothorax after a lung cancer resection is becoming more important. Due to anatomical and physiological considerations and the development of various therapies of nutritional support more conservative treatment is being used. It is our belief that if postoperative chylothorax cases are regarded properly, most will be cured with conservative treatment.
- Received December 9, 2005.
- Accepted January 20, 2006.
- Copyright © 2006 by Tianjin Medical University Cancer Institute & Hospital and Springer
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