Because the esophagus has no plasma membrane, the incidence of postoperative anastomotic fistula is higher than that of gastrointestinal surgery, especially in the cervical esophagus where the incidence of postoperative fistula can be as high as 20%. Once a fistula occurs, the patient’s recovery and life are at stake.
I. Causes of anastomotic fistula
1. High tension of the anastomosis
If fluid is retained in the digestive tract of the substitution esophagus, resulting in increased pressure in the lumen, coupled with postoperative anastomotic tissue edema, the anastomotic nail hole produces a fissure, which expands into a fistula under the corrosion of digestive fluid.
2.Impaired blood supply
A good blood supply is an important guarantee for anastomotic healing. Once the blood supply near the anastomosis is damaged, it will cause insufficient blood supply to the tissue at the anastomosis, affecting healing and even fistula.
3.Impairment of anastomotic integrity
Gastrointestinal reconstruction is the most important part of radical surgery for esophageal cancer and cardia cancer. The anastomotic fistula in the early postoperative period may be related to the impaired quality and integrity of the anastomosis. Since the esophagus has no plasma membrane, the tissue is fragile and vulnerable to injury during separation and reconstruction. Every detail, such as defects, can damage the integrity of the anastomosis.
4.Infection
Anastomotic area with accumulated blood and fluid, intraoperative surgical field contamination, or pinhole-like leakage from the anastomosis can cause local infection or abscess, which can affect the healing of the anastomosis and even cause an anastomotic fistula.
5. Poor general condition
The incidence of anastomotic fistula increases if the patient has a combination of hypoproteinemia, diabetes mellitus, insufficiency of vital organs such as heart, liver, kidney and lung, and systemic malnutrition.
Second, the prevention of anastomotic fistula.
1. Reduce the tension of the anastomosis
(1) Keep the gastric tube open.
Before intestinal motility is restored, the gastric tube drains digestive juices out of the tubular stomach to prevent overexpansion of the stomach and reduce tension. Therefore, it is important to flush the gastric tube and keep it open after surgery.
(2) Enlargement of the diaphragmatic fissure.
The stomach and intestines of the substituted esophagus are usually lifted up to the chest cavity through the diaphragmatic fissure. Part of the diaphragmatic foot should be cut off during surgery to enlarge the diaphragmatic fissure until four fingers can pass. If the enlargement is not enough, the fissure will compress the tubular stomach and form a constricted ring, so that the passage of food is blocked here, causing the tubular stomach to expand with increased pressure, producing retrograde peristalsis or vomiting, which may cause anastomotic fistula.
(3) Pyloroplasty.
In the case of pancreatic cancer, when a large part of the proximal segment of the stomach is resected, because the vagus nerve is cut, the pyloric sphincter is more difficult to relax and food is easily retained in the remnant stomach, which increases the incidence of anastomotic fistula. Therefore, in some cases of pyloric hypertrophy or duodenal ulcer causing pyloric scar, pyloroplasty or substitution of jejunum for stomach can be performed.
2.Good blood supply to the anastomosis
In the radical surgery of esophageal cancer, tubular stomach is often made instead of esophagus. The blood supply of the tubular stomach mainly relies on the right blood vessel of the gastric omentum, which covers 3/5 of the blood supply of the gastric greater curvature side, and the left and short blood vessels of the gastric omentum each cover 1/5 of the blood supply of the region. Because of the poor blood supply to the fundus and the thin gastric wall, the anastomosis is usually chosen in the part of the gastric body with better blood supply, and the fundus is often resected.
The reason for the high incidence of cervical anastomotic fistula may be the long cervical anastomotic pathway and the high tension. The cervical segment of the esophagus has a poor blood supply from the thyroid artery. If the cervical esophagus is anastomosed with the gastric fundus, the incidence of cervical anastomotic fistula is much higher than that of intrathoracic anastomosis because of the high tension and poor blood supply and the weak gastric fundus wall. To ensure good blood supply to the anastomosis, the width of the tubular stomach is about 4 cm, and the width of the anastomosis and the stump and the cut edge of the tubular stomach should be sufficient to ensure a good blood supply to the anastomosis.
3.The integrity of the anastomosis
An intact esophagus is an important condition for anastomosis. When separating the esophagus, try not to damage the esophagus, and suture the whole layer when making the ruffle, without missing the mucosa; when placing the base of the anastomosis, do not damage the mucosa and muscle layer of the esophagus. The length of the esophageal stump outside the purse string is about 5 mm, too long will have tissue caught between the stomach and esophagus, affecting healing; too short will make the anastomosis incomplete. The anastomotic closure should not be pressed too tightly to damage the esophageal wall, and not too loosely to make the staple incompletely formed. When adding sutures to the anastomosis, the knot should be tied so that both sides of the tissue are close together to prevent the sutures from cutting the tissue. When the anastomosis is completed, the inner and outer walls of the anastomosis should be checked for smoothness and integrity. Whether the cut esophagus and stomach wall are intact.
4.Prevent infection in the anastomotic area
Intraoperative contamination and accumulation of blood and fluid in the esophageal bed can easily cause infection and cause anastomotic fistula.
(1) When separating the esophagus, the bronchial artery and esophageal artery from the aorta, the thicker ones should be ligated when disconnected, and the thinner ones can be hemostatically coagulated.
(2) The broken ends of the vessels of the fundus and the lateral side of the greater curvature of the stomach need to be ligated, and the right vessel of the stomach should be sutured to stop bleeding at the cut when making the tubular stomach, and the cut edge of the tubular stomach needs to be reinforced with sutures to prevent splitting and bleeding.
(3) Negative suction bulb should be placed in the esophageal bed for drainage to keep the vicinity of the anastomosis free of accumulated blood and fluid.
(4) To prevent leakage of lymphatic fluid after removal of lymph nodes, the thoracic duct can be ligated.
(5) The thoracic and abdominal cavities should be flushed more often after surgery to reduce contamination.
5.Improve general condition and promote tissue healing
(1) Gastrointestinal surgery requires short-term fasting, so postoperative nutritional support is needed, such as enteral nutrition, intraoperative nutritional fistula or placement of nutrition tube. The nutrition tube should be fixed and kept open.
(2) Hypoproteinemic patients should be supplemented with human albumin or plasma.
(3) Patients with diabetes mellitus should have regular blood glucose measurements and be treated with insulin.
(4) Assist in coughing up sputum and getting out of bed early after surgery to prevent pulmonary infection and intestinal adhesions and other complications.
(5) Keep the chest tube unobstructed to prevent pleural effusion.
III. Judgment of anastomotic fistula
(1) Stomach acid stimulation of the diaphragm will cause severe chest pain, later the infection will form, there will be exudate in the chest cavity and the pain will be relieved, if there is severe chest pain followed by high fever around 39℃, white blood cell count around 15×109/L, neutrophils around 85% and suspicious fluid level in the chest cavity seen on bedside chest X-ray, then anastomotic fistula should be highly suspected.
(2) Oral melanocyte solution, if there is a blue color appearing in the chest drainage tube, then an anastomotic fistula is confirmed.
(3) Oral iodine contrast and x-ray fluoroscopy or radiographs, if there is contrast spillage from the anastomosis, then an anastomotic fistula is confirmed.
(4) Gastroscopy can clearly confirm the existence of anastomotic fistula and can observe the site and size of anastomotic fistula, which is usually performed about two weeks after surgery.
Treatment of anastomotic fistula
In the 1980s and 1990s, anastomotic fistulas were found to be generally reoperated for repair. In the last two decades, due to the application of enteral nutrition, patients with anastomotic fistula are given comprehensive treatment such as supportive therapy to promote natural healing of the anastomotic fistula, and only larger fistulas and necrosis without the possibility of natural healing require secondary surgery.
(1) Strengthen nutritional support, pay attention to the water-electrolyte balance, in addition to enteral nutrition, supplementation of human albumin, plasma and intravenous nutrition.
(2) Keep the gastrointestinal decompression open to prevent gastric acid from spilling out of the fistula and eroding the fistula and intrathoracic tissues.
(3) Select sensitive antibiotics to fight infection and proton pump inhibitors such as omeprazole to inhibit gastric acid secretion and promote fistula healing.
(4) Keep the negative suction flow from the esophageal bed and chest drainage unobstructed so that there is no encapsulated fluid in the chest and anastomotic area to promote adhesions and confinement around the fistula.
(5) If more pus appears in the chest drainage every day, it is recommended to change the drainage tube of the esophageal bed into a flushing tube, flush in a certain amount of saline every day, and ensure that it can be smoothly aspirated from the chest drainage tube. If the flushing fluid cannot be drained, flushing is not advisable. Tracheoesophageal fistula needs to be excluded before flushing to avoid asphyxia.
(6) About two weeks after surgery, a drainage tube can be placed in the fistula through the gastroscope and suction given to facilitate fistula confinement.
(7) After adhesions and confinement around the fistula are present, the residual cavity is cleaned by gastroscopic irrigation and then filled with bioclays to promote healing.
(8) If there is an anastomotic fistula causing localized erosion and bleeding, inject ice saline through the gastric tube after rinsing clean, adding 5 sticks of norepinephrine per 500 ml of ice saline. After injecting 200 to 300 ml, the gastric tube is clamped and retained for a certain period of time, then aspirated and rinsed until there is no blood clot, and then injected with ice saline and retained for hemostasis purposes. Intravenous hemostasis is then achieved with thrombospondin complex and calcium, and blood transfusion if necessary.
(9) If the fistula is large with no possibility of self-healing, it should be repaired surgically as early as possible. Repair materials such as tipped pericardium, diaphragm, chest wall muscle, and greater omentum are available.
Anastomotic fistula is a complication that every thoracic surgeon will encounter in his or her lifetime. Paying attention to every detail of the surgical procedure with a view to reducing the occurrence of anastomotic fistula reduces the pain of the patient and the worry of the physician himself.