Aspiration pneumonia

Introduction to aspiration pneumonia Aspiration pneumonia (aspirationpneumonitis) is a chemical pneumonia caused by inhalation of acidic substances, animal fats such as food, stomach contents, and other irritating liquids and functional hydrocarbons. In severe cases, respiratory failure or respiratory distress syndrome can occur. Patients often have a history of inhalation, rapid onset, more than 1 to 3 hours after the onset of symptoms, clinical manifestations and induced causes, such as aspiration pneumonia caused by tracheal-esophageal fistula, every time after eating, have a cough, shortness of breath . In the case of unconsciousness, there are often no obvious symptoms when inhaled, but after 1 to 2 hours, sudden difficulty in breathing can occur, and purpura and hypotension can occur rapidly, often coughing with a serous foamy sputum, which can carry blood. Both lungs smell wet rales, which can be accompanied by snoring sounds. In severe cases, respiratory distress syndrome can occur. basic knowledge Sickness ratio: 0.05% Susceptible people: no specific population Mode of infection: non-infectious Complications: atelectasis pulmonary edema acute respiratory distress syndrome epilepsy respiratory failure

Cause of aspiration pneumonia

Cough is suppressed (20%):

Normal people have a synergistic effect of epiglottis, glottis, protective reflexes and swallowing. Food and foreign bodies are not easy to enter the lower respiratory tract. A small amount of fluid can also be discharged through coughing. When unconscious, such as general anesthesia, cerebrovascular accident, seizures Alcoholism or hypnotic poisoning, etc. due to uncoordinated swallowing and glottic closure, cough is inhibited, foreign body can be inhaled; esophageal lesions such as esophageal achalasia, upper esophageal cancer, Zenks esophageal diverticulum, food hypopharyngeal can not all enter the stomach Anti-inflow into the trachea; esophageal tracheal fistula caused by cancer or trauma can enter the trachea directly through the esophagus; iatrogenic factors, such as gastric tube stimulation of the pharynx caused by vomiting, tracheal intubation or tracheotomy affect the laryngeal function, inhibit normal Pharyngeal movement, etc., can inhale the vomit into the airway, the elderly are more reactive and more likely to have aspiration pneumonia. Clinically, aspiration pneumonia caused by inhalation of gastric contents is more common, and kerosene, gasoline, dry cleaning agent, etc. are more common. child.

Foreign body (30%):

The severity of pneumonia caused by inhalation is related to the concentration of hydrochloric acid in inhaled gastric juice, the amount of inhalation and the distribution in the lung. When the pH of inhaled gastric acid is <2.5, the lung tissue can be seriously damaged. If the inhaled liquid is as low as 50 ml, it can cause lung damage. In animal experiments, it was confirmed that when the liquid with a pH < 1.5 was inhaled at 3 ml/kg, the animal died 100%. The wider the distribution range of the inhalation liquid, the more serious the damage.

Pathogenesis:

After inhaling the contents of the stomach, gastric acid stimulates the bronchi to cause strong bronchospasm, followed by acute inflammatory reaction of the bronchial epithelium and inflammatory cell infiltration around the bronchi. The gastric juice entering the alveoli rapidly spreads to the surrounding lung tissue, and the alveolar epithelial cells are destroyed, degenerated and involved. Capillary wall, increased permeability of the vessel wall and destruction of the alveolar capillary wall, formation of interstitial pulmonary edema, alveolar edema, edema and hemorrhage in the alveoli gradually absorbed and formed by a transparent membrane after several days, then cause fibrosis, while inhaling Bringing the pharyngeal colonization bacteria into the lungs, producing secondary bacterial infections mainly caused by anaerobic infections, forming lung abscesses, pulmonary edema, weakening of lung tissue elasticity, decreased compliance, decreased lung capacity, and vesicular type II cells Destruction, reduction of surfactant, small airway closure, alveolar collapse caused by atelectasis, insufficient alveolar ventilation, decreased ventilation/blood flow ratio, increased arterial shunt, hypoxemia, massive exudation or reflection of intravascular fluid Vasodilatation, blood volume can be reduced by more than 35%, hypovolemic hypotension can occur, inhalation of hydrocarbon The pathological process of the compound is similar to that of gastric acid inhalation. Because of its low surface tension, it spreads in the lungs after inhalation and inactivates the surfactant. It is more prone to atelectasis and pulmonary edema, leading to severe hypoxemia.

Aspiration pneumonia prevention

The main measures to prevent aspiration pneumonia are to prevent inhalation of food or stomach contents. For example, the stomach should be fully emptied before anesthesia. For patients with coma, head and side positions can be taken to prevent the patient from inhaling foreign matter in an unintentional state. Lung; for anesthesia or coma patients, the stomach tube should be placed as soon as possible, if necessary, tracheal intubation or tracheotomy, strengthening nursing is more important.

Aspiration pneumonia complications Complications atelectasis pulmonary edema acute respiratory distress syndrome epilepsy respiratory failure

Concurrent bacterial infection, resulting at atelectasis, pulmonary edema, hypoxemia, acute respiratory distress syndrome, epilepsy, severe respiratory failure.

Symptoms of aspiration pneumonia Common symptoms Bronchial purulent secretion increased sputum cough wheezing dyspnea snoring hypoxemia Qi stagnation bronchoalveolar retrograde bacterial infection

The clinical manifestations are related to the predisposing factors and the state of the body. Inhalation of vomit can cause sudden reflex laryngeal sputum and bronchial irritation, asthma, cough, aspiration, pneumonia caused by esophagus and bronchospasm, and a coughing cough with shortness of breath after eating every day; Unconscious, often no obvious symptoms after inhalation, but after 1 to 2 hours, you may have difficulty breathing, cyanosis, often coughing a serous foamy sputum, can bring blood, both lungs can smell wet and scream Beep, severe hypoxemia, can produce acute respiratory distress syndrome (ARDS), and can be associated with carbon dioxide retention and metabolic acidosis.

Examination of aspiration pneumonia

The white blood cell count was moderately increased with the left shift of the nucleus, and arterial blood gas analysis showed hypoxemia.

X-ray of the chest shows that the lungs are scattered at irregular edge of the flaky edge 1 to 2 hours after inhalation. The distribution of lesions in the lung is related to the body position during absorption. It is common in the middle and lower lung fields, and the right lung is more common. Pulmonary edema, the flaky shape of the two lungs, the cloud-like shadows merge into a large piece, spread out from the two hilars, with the internal zone of both lungs as obvious, similar to the X-ray findings of cardiogenic acute pulmonary edema However, the size and shape of the heart are normal, and there is no sign of pulmonary venous hypertension.

Bronchoscopy, such as bronchoscopy, has diagnostic value when seeing food particles and other stomach contents in the trachea or bronchi.

Diagnosis and diagnosis of aspiration pneumonia

X-ray of the chest shows that the lungs are scattered at irregular edge of the flaky edge 1 to 2 hours after inhalation. The distribution of lesions in the lung is related to the body position during absorption. It is common in the middle and lower lung fields, and the right lung is more common. Pulmonary edema, the flaky shape of the two lungs, the cloud-like shadows merge into a large piece, spread out from the two hilars, with the internal zone of both lungs as obvious, similar to the X-ray findings of cardiogenic acute pulmonary edema However, the size and shape of the heart are normal, and there is no sign of pulmonary venous hypertension.

Diagnosis of aspiration pneumonia should pay attention to those who are prone to gastric acid inhalation. When they suddenly have difficulty breathing, with or without irritating cough and respiratory failure, they should first be highly suspected.

The diseases to be identified are: cardiogenic pulmonary edema, pulmonary embolism, bacterial pneumonia and other causes of ARDS, such as sepsis and hypotension.

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