Parenteral fistula is a serious complication with unique pathophysiological changes and clinical treatment. The mortality rate was as high as 50-60% before the 1970s and remains at 15-20% today. The relevant issues are discussed below.
I. Current status of treatment of parenteral fistula The treatment of parenteral fistula has first undergone a change in concept. Before 1970, the first choice of treatment after the occurrence of parenteral fistula was emergency surgery to repair the fistula. However, the early surgical failure rate was as high as 80% due to severe intra-abdominal infection and poor healing of unhealthy intestinal collaterals. The main causes of failure are malnutrition and abdominal infection. It was also found that the fistula was gradually enlarged with the development of inflammation and infection, and then gradually reduced with the control of infection and inflammation and tissue repair, and could heal on its own under suitable conditions. This is the pathophysiological process of fistula “from small to large and from large to small”. Therefore, after the 1970s, the principle of treatment for extra-intestinal fistula became drainage first, and then definitive surgery after the infection and inflammation had subsided and the nutritional status had improved.
Thus, the principle of drainage + elective surgery has become the main principle in the treatment of parenteral fistula in the last three decades. The introduction of this principle has led to a dramatic improvement in the success rate of late definitive surgery. In patients treated with definitive surgery in our department, the success rate of surgery is 98.2%. In some patients with extraintestinal fistulas, there is also a certain rate of self-healing (40-60%) after infection control and nutritional support, if there are no factors affecting healing, such as obstruction or specific lesions. However, there is a long waiting period, usually three months, between initial drainage and definitive surgery. During this time patients can experience complications such as endostatic imbalance, bleeding, infection, multiorgan dysfunction and malnutrition. It requires close monitoring and management, a long course of illness, a huge workload, and a huge cost. With the development of medicine, we have also tried to improve this current principle of treatment.
The first thought was to use various methods to promote self-healing of extra-intestinal fistulas. Flushing and drainage, water pressure and total parenteral nutrition support have been proposed to promote self-healing of parenteral fistulas, and in recent years the use of growth inhibitors alone and a combination of growth inhibitors and growth hormone to promote self-healing of parenteral fistulas has been investigated, greatly improving the self-healing rate. In patients with appropriate tubular fistulas, they generally heal on their own. Some patients with labyrinthine fistulas may also heal spontaneously after revision.
Another change to the classical principles of treatment of parenteral fistulas is a renewed attempt at early definitive surgery. In fact, attempts to perform early definitive surgery for enterocutaneous fistulas have never ceased. The advent of new clinical tools, such as advances in the treatment of abdominal and systemic infections, the advent of the anastomosis, and the improvement in the level of organ support, has prompted us to try early definitive surgery for enterocutaneous fistulas in order to reduce the consumption of long-term hospitalization, but the results have not been satisfactory. Analyzing the reasons for multiple surgical failures, the patient’s ability to grow and heal is the key to the success of the intestinal anastomosis. Recently, the addition of growth hormone after early definitive surgery has made it possible to remove the intestinal fistula intestine in one stage and perform intestinal anastomosis in case of abdominal infection. In the future, experience should be accumulated on this basis and its indications and contraindications should be further explored.
Early resection of the fistula intestine with intestinal anastomosis is a negative process in the history of the treatment of fistula.
The current treatment of extra-intestinal fistula is mainly based on the patient’s specific condition. In the drainage of “drainage + elective surgery” based on the active promotion of self-healing therapy and early definitive surgery for extra-intestinal fistula.
(a) Intra-abdominal bleeding: Intra-abdominal bleeding is an early complication of extra-intestinal fistulas, especially duodenal fistulas and high jejunal fistulas. The site of hemorrhage can be the eroded and digested blood vessels in the abdominal cavity, the margin of the fistula, the granulation tissue of the fistula, or the stressful mucosal erosion of the gastrointestinal tract. The site and cause of bleeding should be understood as much as possible.
Measures to stop bleeding include (1) reducing digestion of the tissue around the fistula by digestive juices. Specific methods include shunting of digestive juices. Shunting of gastric, bile and pancreatic juices is one of the ways to prevent and treat bleeding from an enterocutaneous fistula. The main cause of bleeding from an extraintestinal fistula is the digestive erosion of the intestinal mucosa and surrounding tissues by the leaking intestinal fluid. In particular, the action of pancreatic enzymes such as proteases is an important cause of digestive bleeding of tissues. Therefore, by blocking the activation of pancreatic enzymes, the digestion of the tissue and subsequent bleeding is also blocked. -Drainage of digestive fluid: Poor drainage is a common cause of bleeding from extraintestinal fistulas. In many patients, when passive latex drainage is replaced by active negative pressure drainage, the bleeding stops quickly. It is important to note that this active negative pressure drainage should be a drip double-lumen negative pressure suction tube (Ri’s tube). There are single-lumen negative pressure suction used, but the significance of drainage is lost due to the tendency of the tube tip to adsorb tissue. Reduce the secretion of digestive juices: the secretion and leakage of large amounts of digestive juices is the root cause of extra-intestinal fistula, and this can be achieved by growth inhibitors. (2) Stopping the bleeding by surgical and other interventions: re-suturing the bleeding point by caesarean section and selective arterial embolization under X-ray fluoroscopic guidance are feasible. (3) Promote coagulation and vasoconstriction: systemic use of lithotripsy, local use of thrombin, flushing with norepinephrine solution, alkalinization of gastric juice, gastric flushing.
(2) Abdominal and systemic infections Abdominal and systemic infections are still the main cause of death in patients with parenteral fistula. The current treatment of abdominal cavity infection is mainly an effort in surgical drainage, rational application of antibiotics and micro-ecological immune nutrition.
Surgical treatment measures for abdominal infections include early drainage surgery, extensive intraoperative abdominal irrigation, and continuous postoperative irrigation and drainage with a drip dual-lumen negative pressure suction tube. For severe abdominal infections, open abdominal therapy and repeated dissection and irrigation may also be used. To avoid extraintestinal fistula and incisional hernia due to intestinal tube exposure after open abdominal therapy, a temporary open abdominal technique may be used. For subdiaphragmatic abscesses and abscesses in the abdominal spaces, fine needle aspiration can also be performed under ultrasound or CT guidance to flush the abscess cavity.
In the treatment of abdominal infections, attention should also be paid to the rational use of antibiotics. When the infection first develops, antibiotics can be used empirically according to the clinical characteristics of the infection and the nature of the pus and previous treatment medications, while bacterial culture and drug sensitivity tests of the relevant body fluids should be performed. The use of antibiotics can be adjusted later according to the response to treatment and the results of bacterial culture. The results of bacterial culture should be regularly analyzed statistically for empirical drug use reference. In the case of effective drainage of the infection, there is no need to give antibiotics for a long time to avoid the development of bacterial resistance leading to secondary infection.
Improvement of dysbiosis through microecological nutrition. Improving the immune barrier of the intestine and systemic immune function by means of immunonutrition. Short-chain fatty acids or dietary fiber, which are specific energy substances for the colonic mucosa, should also be provided. Provide normal bacteria, such as Lactobacillus, if necessary, to improve the barrier function of the colon through microecological nutrition. Reduce or eliminate the occurrence of intestinal flora translocation.
(iii) Multi-organ dysfunction (MODS) Recurrent bleeding and infection in patients with enterocutaneous fistula can eventually lead to multi-organ dysfunction, which is more likely to occur in elderly, diabetic and malnourished patients. Multi-organ dysfunction is also a major cause of eventual treatment failure in patients with enterocutaneous fistulae. It has been recognized that there is a process from multiple organ dysfunction to complete failure, and that multiple organ dysfunction should be actively prevented and treated along with treatment of bleeding, infection, and other primary diseases. When respiratory dysfunction occurs, tracheotomy and ventilator support should be performed early. For the early stage of renal dysfunction, drugs such as tachyphylaxis should be used promptly to promote renal tubular perfusion, and if necessary, bedside hemodialysis should be performed. Efforts should also be made to improve the portal blood supply and prevent the failure of liver and intestinal function.
(iv) Malnutrition and nutritional support Malnutrition is a problem that must be addressed throughout the treatment of patients with extra-intestinal fistula. Nutritional support is one of the main treatments for patients with parenteral fistula.
The advent of total parenteral nutrition (TPN) has led to a significant decrease in the mortality rate of parenteral fistulas and has changed the treatment strategy for parenteral fistulas. The traditional view also considered TPN as the only method of nutritional support for parenteral fistulas. However, the complications of depression and infection associated with TPN often interfere with the continuous treatment of parenteral fistulas. In contrast, enteral nutrition (EN) can solve the challenge of infection and liver function impairment due to TPN. When introducing the nutritional support therapy for parenteral fistula in the 1970s, Lai Jieshou already observed that the effect of enteral nutrition was better than that of parenteral nutrition. It is suggested that the enteral nutrition support for patients with parenteral fistula should be emphasized, and it is advocated that the nutrition should be supplemented from the intestine when the fistula is controlled and the overflowing intestinal fluid can be effectively drained outside the abdominal cavity. However, it is also difficult to start enteral nutrition support in patients with parenteral fistula. In response to the loss of intestinal integrity and continuity and intestinal fluid loss in patients with parenteral fistula, there is a goal, which is “If the gut function, use it. ” This principle can be understood specifically as follows: if the gut function is normal, the gut should be used; if there is a segment of the gut that functions normally, use this segment of the gut —- to give the art of the pathway; if the gut has a part of digestive function, use this part of digestive function —- the art of formulating enteral nutrition; if a segment of the gut has a part of function, also use this segment that has a part of If a section of the intestine is partially functional, use that partially functional section of the intestine as well —- to give the perfect combination of pathway and formula.
In summary, the routes of enteral nutrition giving in patients with parenteral fistula include transnasogastric tube, nasogastric tube, gastrostomy tube, jejunostomy tube, collection and reinfusion method, and also the implementation of enteral nutrition by temporarily restoring the integrity and continuity of the intestinal tract through water pressure and piece plugging. Depending on the loss of intestinal fluid, elemental meals, semi-digestible and full molecular mode enteral nutrition solutions are available. Tissue-specific nutritional factors, such as glutamine and dietary fiber, should also be supplemented appropriately.
The introduction of enteral nutrition support in enterocutaneous fistulas is a challenge to clinical nutrition that requires repeated attempts and benefits when successful. The role of enteral nutrition in the treatment of parenteral fistulas can be understood in this way: if a patient can successfully resume enteral nutrition, that patient is saved. This has been a highly successful response to malnutrition in the treatment of parenteral fistulas.
It is important to acknowledge that TPN remains an important means of nutritional support for patients with parenteral fistulas, and in recent years we have continued to use parenteral nutrition in 44.6% of cases despite the extreme use of enteral nutrition. When enteral nutrition cannot fully meet the energy and protein needs, it can be supplemented by parenteral nutrition, i.e. “PN+EN” model, which is also a more successful model of nutritional support for critically ill patients.
（Once an extra-intestinal fistula has occurred, the treatment process is longer and more costly than that of ordinary diseases, regardless of the treatment method. The treating physician should especially implement the modern medical model of “social, psychological and physiological” to overcome impatience. Communicate with patients and families in all stages of treatment in a timely manner, and have some psychological preparation for various complications to reduce the conflicts between doctors and patients. At the same time, we try to make patients get rid of “heavy patients” psychology, avoid various complications introduced by long-term bed rest, and promote patients’ recovery.
The trend of development of trauma, tumor patients and the popularity of various new treatments, it is difficult to reduce the trend of parenteral fistula patients for some time in the future. In-depth and extensive research should be conducted on the prevention and treatment of parenteral fistulas in the future.
The data of patients with parenteral fistula should be analyzed frequently to discover the etiology and characteristics of parenteral fistula caused by various treatment methods at various stages, and to propose corresponding preventive measures to guide clinical practice. For example, the number of fistulas caused by radiation intestinal injury has increased in recent years, and attention should be paid to the protection of the intestinal canal during radiotherapy.
Clinical studies have found that different fistulas have different characteristics and treatment methods. In the future, a relatively standard treatment plan should be proposed for each type of fistula. For example, the treatment plan for extra-intestinal fistula caused by radiation bowel injury, extra-intestinal fistula complicated by severe pancreatitis, extra-intestinal fistula combined with inflammatory bowel disease, and duodenal stump fistula. Research should also be conducted on the treatment of various complications of fistulas, such as intestinal adhesions.
A national center for the treatment of fistula should be established to improve the rate of fistula treatment. Episiotomy is an extremely serious complication that is not often encountered by every general surgeon. Doctors and departments that encounter fistulas often lack the experience, methods, and equipment to do so, and it is not possible to set up special equipment specifically for the treatment of individual fistulas. The treatment process is prone to detours and high consumption/efficiency. Therefore, most foreign scholars advocate the establishment of a dedicated national center for the treatment of parenteral fistulas with a ladder network. Once a fistula has occurred, the treating physician can receive guidance through various means, such as the Internet, and if necessary, be transferred to an enterocutaneous fistula treatment center to be treated by a specialist in a timely manner, thus increasing the cure rate and improving the cost/benefit ratio.