Earlier this year, a 19-year-old male soldier, during a mission infected with “renal syndrome hemorrhagic fever”, in the local anti-inflammatory, liver, kidney, tracheal intubation, whistle machine to assist in the whistle and other symptomatic treatment, the patient’s condition gradually stabilized, but later recurring lung infection, gastrointestinal distension and other symptoms. A tracheoesophageal fistula of about 1 cm in length was found after a gastrointestinal tract imaging at a local hospital.
After admission, fiberoptic bronchoscopy showed that the fistula was located 3 cm below the vocal cords, from the second tracheal ring down to the sixth tracheal ring, about 5 cm long and 2 cm wide, oval in shape, with a defect in the tracheal membrane, and connected to the esophagus. The hospital immediately organized a hospital-wide expert consultation and saved the young soldier’s life after surgical repair of the fistula, esophagoplasty, tracheal end-to-end anastomosis, tracheotomy, and symptomatic supportive treatment with antibiotics for lung infection.
How does a tracheoesophageal fistula (TEF) form? What are the factors that influence its formation? What are the effects on the organism? How is it diagnosed and treated?
TEF includes both congenital and acquired, while acquired TEF is most commonly caused clinically by air sac compression following the establishment of an artificial airway. The establishment of an artificial airway, including tracheal intubation and tracheotomy, is very important for keeping the airway open and saving the lives of critically ill patients, and its common complications are bleeding, infection, subcutaneous emphysema, and prolapse of the artificial airway, while tracheoesophageal fistula is a relatively rare but very serious complication, with an incidence of about 0.5% to 1%. If not treated in a timely manner, severe aspiration leads to infectious shock, which can endanger the patient’s life.
The mechanism of TEF formation is: after the artificial airway is established, the membrane tissue of the posterior tracheal wall leads to ischemic necrosis due to compression and then ulceration, which in turn can lead to infection, increased inflammation and necrosis, and the continuous destruction of the tracheal membrane and further development of necrosis penetrates the esophagus, leading to the occurrence of TEF. The pathological changes are often accompanied by an ulcer formation process and the fistula is larger on the tracheal surface than on the esophageal surface, among other features.
It has been found that there are more factors affecting the formation of TEF, which include.
1, excessive air sac pressure. This is the most important reason for the occurrence of TEF. Tracheal intubation or tracheotomy cannulae have air sacs for fixing the position and preventing air leakage and misaspiration. Studies have shown that tracheal mucosal capillary perfusion is significantly reduced when the balloon pressure is >30cmH2O, and the tracheal mucosal blood supply is completely blocked when the balloon pressure is ≥50cmH2O. Therefore, excessive balloon pressure and prolonged compression of the trachea will lead to irreversible ischemic necrosis of the tracheal wall. At present, it is believed that the ideal airbag pressure should be 15~25cmH2O, which can effectively close the airway and prevent the compressive damage of the airbag on the mucosa.
2, the time of artificial airway establishment. Studies have shown that as the time lengthens, the damage to the tracheal wall caused by airbag compression also increases. On the one hand, prolonged airbag compression can lead to local ischemia and edema of the tracheal mucosa, on the other hand, prolonged use of the same tracheal intubation or tracheotomy cannula, its airbag appears to age and lose elasticity, and the inflation volume and inflation pressure of the airbag keep increasing, causing local damage and rupture of the tracheal mucosa, which leads to the occurrence of TEF.
3, pressure in the airway. It is believed that even if the balloon is correctly filled, if excessive airway pressure is given during mechanical ventilation it can lead to ischemic damage to the airway mucosa, thus promoting the formation of TEF.
4, mechanical injury. After the artificial airway is established in the adjustment of its position without first balloon deflation forced pulling causes mechanical wear and tear of the trachea; artificial airway fixation belt is too loose, the patient appears agitation, cough or position change, etc., so that the catheter moves up and down, which can also cause chronic injury to the airway mucosa. In addition, excessive negative pressure during suction or prolonged negative pressure suction and repeated suction at the same site can cause damage to the tracheal mucosa.
5. Other factors: ICU patients are in heavy condition, and a variety of chronic underlying diseases such as hypoproteinemia, anemia, malnutrition, etc., as well as long-term use of hormones can make the tracheal mucosa thin and prone to breakage and infection, which are not easily repaired. Secondly, the airway confinement and sterile environment are damaged after the artificial airway is established, and repeated lung infections and infectious shock cause local hypoperfusion, resulting in the breakdown of the tracheal mucosa due to infection, ischemia, and necrosis.
Once TEF occurs, patients with an established artificial airway may present with choking after eating, food residues found in the artificial airway with bloating and increased secretions, oropharyngeal air leakage during mechanical ventilation, recurrent pulmonary infections or aggravation of pulmonary infections, and TEF should be suspected.
TEF can be diagnosed by.
1, a fistula between the trachea and esophagus visible by endoscopy (fiberoptic bronchoscopy, gastroscopy, etc.).
2, injection of methylene blue solution from the gastric tube, aspiration of blue fluid via tracheal aspiration, or blue fluid leaking from the posterior wall of the trachea as found by fiberoptic bronchoscopy.
3. Spiral CT scan of the neck, with a large fistula visible as tracheal and esophageal penetration. Any of the above methods can confirm the diagnosis.
TEF can lead to uncontrollable aspiration pneumonia, and patients in mechanical ventilation can suffer from inadequate effective alveolar ventilation, hypoxemia and carbon dioxide retention due to gas entering the digestive tract through the fistula, which can seriously affect the patient’s treatment and threaten the patient’s life, with an average survival period of only 1-6 weeks if not treated promptly.
At present, the common clinical treatment means include.
1, conservative treatment: active treatment of the primary disease, strengthening nutritional support, nasal feeding diet, local open fistula, and moving the artificial airway balloon to the distal end of the fistula to inflate, to promote the healing of the fistula as well as to prevent gastric reflux causing aspiration, this method is suitable for TEF with small fistula.
2, artificial stent implantation: there are more reports on the application of endoscopic placement of tracheal or esophageal stent implantation to close the fistula at home and abroad, this method is safe, simple and effective, its common complications are restenosis, bleeding, secondary TEF and stent displacement. Since TEF fistulas caused by artificial airway establishment are often located in the upper trachea and cervical esophagus, and esophageal stents tend to migrate into the pharynx, patients can experience unbearable foreign body sensation, so currently endoscopic stent implantation is mostly used in some patients with TEF who cannot tolerate surgical repair in the short term. There are various options for stent implantation, and stents that are easy to bend and easy to remove should be chosen in the selection.
3. surgical repair. Currently surgical repair to close the fistula is the treatment of choice for TEF after artificial airway establishment. For a clear diagnosis and systemic conditions, surgical treatment should be performed as soon as possible. The common surgical procedures include simple suture repair, material repair and resection and reconstruction of the trachea or esophagus, which should be selected according to the location and size of the fistula, the site of the lesion and the patient’s physical condition.