Aspiration pneumonia (aspiration pneumonitis) is a chemical pneumonia caused by the inhalation of acid substances, animal fats, such as food
Aspiration pneumonia (aspiration pneumonitis) is a chemical pneumonia caused by the inhalation of acid substances, animal fats, such as food, stomach contents, and other irritants and hydrocarbon compounds. Severe respiratory failure or respiratory distress syndrome.
Clinical aspiration of gastric contents, due to gastric acid caused by pneumonia is more common than inhaled hydrocarbon liquid, and more important. Kerosene, gasoline, dry cleaners, furniture polishing agent, and sometimes can be mistaken, more common in children. Normal people due to the protective effect of laryngeal reflex and swallowing synergy, the general food and foreign body is not easy to enter the lower respiratory tract, even if a small amount of liquid aspiration, but also through coughing. In the confusion when general anesthesia, cerebrovascular accident, epilepsy, alcoholism, or overdose of anesthesia sedative, defense function to weaken or disappear, foreign body can be inhaled trachea; esophageal lesions such as esophageal achalasia, esophagus cancer, Zenker esophageal diverticulum, food tube into the stomach, can not swallow all into the trachea; tracheoesophageal fistula caused by various reasons, food can be directly into the trachea through esophagus; iatrogenic factors such as gastric stimulation pharynx causes vomiting; tracheotomy or tracheal intubation effect of laryngeal function, inhibit the normal eye movements, the inhalation of vomit airway. Older people are more prone to poor response.
Because of the stimulation of gastric acid, the acute inflammation of the lung is caused by the stimulation of gastric acid, and its severity is related to the concentration of hydrochloric acid in the gastric juice, the amount of inhalation and the distribution of the lung. Inhalation of acid pH is less than or equal to 2.5, the amount of inhaled 25ml that can cause lung injury serious. Animal experiments confirmed that inhalation of pH 1.5 of the liquid 3ml/kg weight can be lethal. The wider the distribution range, the more serious the damage.
After inhalation of gastric juice, gastric acid can immediately cause chemical burns in the airways and lungs. Stimulation of the bronchial tube leads to a strong spasm of the tube wall, resulting in acute inflammation of the bronchial epithelium and inflammatory infiltration around the bronchi. Into the alveolar gastric juice quickly spread to the lungs, causing the global destruction of epithelial cells, degeneration, and involvement of the capillary wall, the vessel wall permeability, liquid oozing blood vessels, edema and hemorrhage caused by pneumonia. At the same time due to the destruction of alveolar capillary membrane, the formation of interstitial pulmonary edema. A few days later, alveolar edema and hemorrhage were gradually absorbed and replaced by hyaline membrane. For a long time the formation of pulmonary fibrosis. Inhalation of food or foreign if the pharyngeal microflora into the lungs, can lead to secondary bacterial infection with anaerobic bacteria. The formation of pulmonary abscess. Pulmonary edema in the lung tissue elasticity and compliance, reduce lung volume reduction, and reduce the pulmonary surfactant, small airway closure, alveolar collapse caused by micro atelectasis, may have inadequate ventilation, ventilation / perfusion imbalance and venous arterial shunt increased, resulting in hypoxemia or with metabolic acidosis. A large number of blood vessels in the blood vessels or reverse the expansion of blood vessels, can produce hypotension. The pathological process with the acid hydrocarbon inhalation inhalation is similar, because of its low surface tension, immediately after inhalation lung diffusion in large area, and the surfactant inactivation, and is easy to produce atelectasis, pulmonary edema, severe hypoxemia.
Patients often have a history of inhalation causes, rapid onset, more than 1 to 3 hours after the onset of symptoms, clinical manifestations and etiology of induced tracheoesophageal fistula, such as the cause, each in after eating a spasmodic cough, shortness of breath. In her case, inhalation often no obvious symptoms, but 1 to 2 hours after the sudden onset of dyspnea, cyanosis and hypotension rapidly, often expectoration serous foamy sputum with blood. The smell of two lung wet rales, with eosinophilic stridor. Severe respiratory distress syndrome.
Chest X-ray is shown in 1 to 2 hours after inhalation can see two lung scattered shadows in irregular fuzzy edge, lung lesions distribution and absorption position, common in the middle and lower lung fields, the right lung was more common. Pulmonary edema occurred in two lung flake, cloudy shadows confluent sheet, spread out from two to two in the lung hilum, with obvious, similar with acute cardiogenic pulmonary edema X-ray manifestations, but the heart of the size and shape of normal, no signs of pulmonary venous hypertension.
In case of emergency, should be immediately given high concentration oxygen inhalation, application of bronchoscopy or tracheal intubation with foreign body aspiration, positive end expiratory pressure breathing "treatment of acute respiratory distress syndrome". Correct hypovolemia by albumin or dextran. Diuretics can be used to avoid left ventricular overload and colloid fluid leakage into the interstitium. The application of adrenal cortex hormone therapy is still controversial, it is considered that the use of glucocorticoids within 12 hours of inhalation of a large amount of glucocorticoids ~ 4 ~ 3, is conducive to the absorption of pulmonary inflammation, but also have the opposite opinion. Antibiotics are only used to control secondary infection, but not to prevent bacterial infection, because the drug can not reduce the incidence of secondary bacterial infection, and easy to produce drug-resistant strains. The principle of treatment after inhaling hydrocarbon liquids.
The main preventive measures for preventing food or gastric contents such as inhalation anesthesia before the operation should be sufficient to gastric emptying in patients with coma can take the head and lateral position, as soon as possible to place the tube, when necessary for tracheal intubation or tracheal cut. Strengthening nursing is more important.