Acute eosinophilic granulomatous pneumonia

　　1. Etiology

　　The etiology is not yet clear, and it is generally believed to be related to the inhalation of allergens in the environment, and it is speculated to be a hypersensitivity reaction caused by unknown allergens.

　　2. Pathogenesis

　　The main pathological change is acute diffuse alveolar damage. Eosinophilic infiltration is evident in the alveolar腔, interstitium, and bronchial wall, with most cases showing the formation of hyaline membranes and hyperplasia of type II alveolar epithelial cells. In the later stage, interstitial edema, massive infiltration of inflammatory cells, and fibrous tissue proliferation can be observed. There is no evidence of vasculitis or damage to extrapulmonary organs.

　　A few cases may develop severe acute respiratory failure. Patients present with an acute febrile appearance, flushed cheeks, flaring nostrils, hot and dry skin, herpes simplex on the corners of the mouth and the nasal axis; in cases of extensive lesions, cyanosis may appear; in cases of sepsis, skin and mucosal hemorrhagic spots, jaundice of the sclera may appear; when the meninges are involved, neck stiffness and pathological reflexes may occur. Heart rate may increase, and sometimes arrhythmia may occur. In the early stage, there are no obvious abnormalities in pulmonary signs, only a decrease in the amplitude of chest breathing movement, mild dullness, reduced respiratory sounds, and pleural friction sounds. In the consolidation phase, percussion may present as dullness, tactile vocal resonance may be enhanced, and bronchial breathing sounds may be present as typical signs. During the resolution phase, moist rales may be heard. In severe cases, intestinal distension may occur, and upper abdominal tenderness is often related to inflammation involving the diaphragmatic pleura. In severe infections, shock, acute respiratory distress syndrome, and neurological symptoms may occur,表现为 confusion, irritability, dyspnea, somnolence, delirium, and coma.

　　Some patients may have a history of allergies, present with acute onset, and表现为 fever, muscle pain, cough, dyspnea, chest pain. The diagnosis of acute eosinophilic granulomatous pneumonia must first exclude other causes of pulmonary eosinophilic infiltration.

　　1. Strict implementation of disinfection and isolation system This mainly refers to medical staff and hospital environment and equipment, strictly washing hands and wearing gloves before and after contact with patients, regular environmental and indoor disinfection and ventilation, regular cleaning and disinfection of respiratory treatment devices, regular replacement of mechanical ventilation and atomizer tube lines, and adopting a complete set of strict hospital infection monitoring and prevention plan. It is reported that the hospital infection rate is 20% lower in hospitals that adopt this plan compared to those that do not.

　　2. Gut decontamination treatment is a preventive measure commonly used in Europe in recent years, mainly aimed at susceptible populations in hospital infections, with the purpose of removing bacterial colonization and growth in the gastrointestinal tract. Methods include total gut decontamination and selective gut decontamination, with the latter being more commonly used. It involves the use of polymyxin B, tobramycin (gentamicin or neomycin, etc.), and amphotericin B, which are not absorbed by the gastrointestinal tract, administered via nasogastric feeding or oral administration for 5 consecutive days, and the systematic application of cephalosporins every day to remove aerobic bacteria from the oropharynx and gastrointestinal tract without reducing the number of anaerobic bacteria. Its preventive effect is particularly evident in Gram-negative bacilli. According to the author's statistics of relevant literature, the decontamination group almost had no secondary pneumonia caused by Klebsiella pneumoniae and respiratory tract infections (individual cases were resistant strains).

　　3. The main purpose of protecting the stomach acid barrier is to prevent stress ulcers by using drugs such as sucralfate (ulcerlmin). It can prevent bleeding from stress ulcers and, due to its ability to adsorb gastric mucosa, change gastric mucus, increase the content of prostaglandin E2 (PGE2) in the gastric cavity, and absorb pepsin, it does not change the acidic environment inside the stomach, thereby effectively preventing ulcers and infections. Moreover, according to literature, sucralfate also has intrinsic bactericidal activity. A series of studies have shown that the incidence of pneumonia in the group using antacids is 23% to 35%, while the incidence of pneumonia in the group using sucralfate is 10% to 19%.

　　1. The total white blood cell count in peripheral blood is significantly increased, while the increase in eosinophils is not obvious, but the eosinophils in BALF are significantly increased, and the classification count is often greater than 25%.

　　2. The levels of interleukin-5 and vascular endothelial growth factor (VEGF) in BALF are often elevated.

　　3. Serum total IgE levels are moderately elevated. Hypoxemia (PaO2

　　4. X-ray examination shows early chest X-ray manifestations of faintly dense spot-like infiltrative shadows, which may have Kedey B line, and can rapidly (within 48 hours) develop into bilateral lung diffuse and symmetrical distribution of alveolar and interstitial infiltration, similar to the hazy or micronodular manifestations of ARDS. There may be a small to moderate amount of pleural effusion.

　　5. CT scan shows diffuse lung parenchymal infiltration.

　　6. Pulmonary function tests show restrictive ventilatory function damage with associated diffusion dysfunction.

　　7. Pleural effusion has a higher pH and contains a large number of eosinophils.

　　Different dietary requirements are required according to different symptoms, please consult a doctor specifically, and formulate different dietary standards for specific diseases. The patient's diet should be light and easy to digest, eat more vegetables and fruits, reasonably match the diet, and pay attention to sufficient nutrition. In addition, patients should also pay attention to avoid spicy, greasy, and cold foods.

　　1. Treatment

　　Adrenal cortical hormones are the first-line treatment, and symptoms can be relieved within a few hours of treatment, and lung infiltration can completely disappear within 1-2 weeks. Commonly used methylprednisolone 60-125mg/6h, after symptom control, change to prednisone 40-60mg/d orally for 2-4 weeks, and then reduce the dose and stop the medication.

　　2. Prognosis

　　Some can be spontaneously relieved. After recovery, this condition will not recur. The prognosis of acute eosinophilic pneumonia is generally good.