Lung blast injury

Introduction to lung blast injury Due to high-pressure boilers, chemicals or gas explosions, in the war, due to strong explosives or nuclear explosions, huge amounts of energy can be released instantaneously, causing the pressure and temperature at the center of the explosion to rise sharply and rapidly spread around, thus forming a supersonic speed. High-voltage waves, that is, shock waves. Continuous overpressure-negative pressure of air shock wave or underwater shock wave acts on the human body, causing rapid compression and expansion of the chest and abdomen, causing a series of hemodynamic changes, causing damage to the heart, lungs and blood vessels; the body gas is overpressure-negative Under the action of pressure, an implosion effect is generated to damage the gas-containing tissue (such as alveolar); when the pressure wave passes through different density tissues, the reflection at the interface causes the fragmentation effect, causing damage; and the different density of the tissue is affected by the same pressure wave. After that, the speed differs due to the difference in inertia, tearing and bleeding occur at the joint, and the damage caused by the above shock wave itself directly acting on the human body is called a blast injury. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: pneumonia, respiratory failure, sepsis, shock

Cause of lung blast injury

Trauma factor (95%)

In the event of an explosion, the wounded were mostly near the explosion point. The huge air wave (ie shock wave) generated after the explosion attacked the wounded chest and the chest wall hit the lung tissue. Due to the reaction principle, the lungs collided back against the chest wall after the shock wave passed. And the reduced damage, causing rupture and bleeding of the pulmonary parenchyma, and the surface of the lung corresponding to the rib is particularly obvious. The damage caused by the shock wave itself directly acting on the human body is called blast injury, and at the same time, the dynamic pressure of the shock wave (high-speed airflow impact) Force) throwing and impacting the human body and acting on other objects and causing indirect damage to the human body. The high temperature of the shock wave can cause burns on the surface or respiratory tract. The shock wave can damage all tissues and organs of the human body, and the gas-containing organs are particularly vulnerable to damage, tissues and organs. The degree of damage depends on the magnitude of the pressure peak, the length of the positive pressure action and the speed of the pressure rise. The clinical characteristics of the impact injury:

More than 1 injury, often multiple injuries or combined injuries, complex injuries;

2 external light internal weight, body surface can be intact, but there are obvious symptoms and serious visceral damage;

3 rapid development, more than 6 hours after injury can also develop to the peak within 1 to 2 days after injury. Once the body compensation function is out of balance, the injury can be turned down and down, it is difficult to treat. In theory, the impact injury includes both shock wave super Direct damage caused by pressure-negative pressure, that is, blast injury, also includes damage and burn caused by dynamic pressure, but clinically, impact injury and blast injury are often confused.

Pathogenesis

When the high-pressure air wave or water wave generated by the explosion hits the chest, the chest wall can hit the lung tissue. The negative pressure wave following the high pressure can also cause the lung to collide with the chest wall, causing pulmonary contusion, pulmonary capillary hemorrhage, small bronchi and alveolar rupture. The alveoli are filled with blood and tissue fluid, lose ventilation and diffuse function, severe hypoxia; extensive pulmonary edema in the lung tissue, severe pulmonary fissure, can cause hemothorax and pneumothorax, in addition, gas can enter the pulmonary blood circulation to cause air embolism If a large number of air sacs enter the cerebral artery and coronary arteries, it can cause immediate death.

Lung blast injury prevention

Before the explosion is discovered, if it is too late to escape, it should be placed on the ground or in the nearby concave area immediately, and it should be directed to the explosion point. Thus, in the dead zone outside the fan-shaped shock wave, it can reduce or avoid the damage of the shock wave. Prevention is most important to actively prevent the occurrence of various complications.

Pulmonary blast injury complications Complications pneumonia respiratory failure septic shock

The most common and serious complications of this disease include pulmonary infections, ARDS and MODS.

1, pneumonia

Pulmonary blast injury is common in lung disease, which is associated with impaired capillary capillaries, impaired alveolar membrane, increased alveolar permeability, decreased or inactivated alveolar surfactant, resulting in pulmonary infection .

2, ARDS

The lung changes in patients with acute respiratory distress syndrome (ARDS) are caused by extensive alveolar microvascular damage, which increases the permeability of endothelial cells, causes alveolar hemorrhage and edema, and finally leads to increased dead space and shunt in the lungs. Lung compliance and oxygenation are worse, resulting in clinical respiratory distress. In general, pathological changes include three phases: exudates, proliferative, fibrosis, and current acute Respiratory distress syndrome patients are less likely to die of respiratory failure (<5%), and most die from sepsis or multiple organ failure, with a mortality rate of about 50%. For patients, the degree of lung fiber also determines the patient's future lung function.

3, MODS

Multiple organ dysfunction syndrome (MODS) is a process of severe trauma, burns, large abdominal surgery, shock and infection. At the same time, there are more than two organ damages and even failures in the country or in succession. After the occurrence, MODS includes the process of organ damage from light to heavy, the abnormal physiological function of the organ occurs in the light, the organ reaches the organ, and the degree of systemic failure is called multiple organ failure. In patients with lung blast injury, often It is a trauma, burns and lungs coexist, shock and infection are also very common, so there is a very large risk of concurrent MODS.

Pulmonary blast injury symptoms common symptoms chest pain atelectasis dyspnea convulsion shock chest tightness

The main pathological changes of lung blast injury are alveolar rupture and intra-alveolar hemorrhage, followed by pulmonary edema and emphysema, sometimes accompanied by pulmonary rupture. Pulmonary hemorrhage can range from speckle to diffuse, and severely visible parallel strips corresponding to intercostal space. Pulmonary parenchymal hemorrhage, rupture of blood vessels in the lung parenchyma can form a hematoma, and even blood clots can block the trachea and cause rapid death. The pulmonary edema is mild or the alveolar cavity contains a small amount of effusion, and in severe cases, a large amount of edema can be seen. The liquid overflows into the bronchus and even in the trachea. It is often mixed with blood and is a bloody foam. Pulmonary hemorrhage and edema can cause atelectasis. Emphysema can be interstitial or alveolar. In severe cases, blood and gas are present under the pleura. Pulmonary bullae can cause hemothorax or blood pneumothorax when a lung rupture occurs.

The clinical manifestations of lung blast injury vary according to the severity of the injury. The main symptoms are hemoptysis, vomiting, and qi stagnation. In severe cases, respiratory failure occurs. Cerebral qi stagnation may have neurological symptoms, convulsions, and lethargy. Even coma, lung auscultation is full of wet voice, lung X-ray examination in addition to lung field showing spotted or flaky shadows and other invasive changes, often pneumothorax, hemothorax signs, in the emergency examination of patients, chest wall or facial contour No trauma was found, but the patient was mostly in a state of drowsiness. He was speechless and reluctant to answer. He was extremely difficult to breathe. He was vomiting, and most patients had hemoptysis. Because of severe pulmonary damage complicated with right heart failure or coronary artery thrombosis complicated with acute myocardial infarction, Causes severe arrhythmias and hypotension; shock waves from explosions can also cause brain and spinal cord contusions.

Cerebral vascular thrombosis, respiratory and circulatory failure are caused by cerebral ischemia and coma, shock waves can also break the eardrum and cause gastrointestinal bleeding. The lighter only has short-term chest pain, chest tightness or suffocation, and slightly heavier within 1 to 3 days after injury. Cough, hemoptysis or bloodshot sputum, a few have difficulty breathing, auscultation can be heard and variable spatial wet rales or sputum pronunciation, severe cases can have obvious breathing difficulties, cyanosis, bloody foam sputum, etc., often accompanied by shock, check In addition to the lungs, there may be signs of lung consolidation and blood gas chest signs. In addition, there are often other organ damage manifestations. X-ray examination shows thickened lung texture, patchy shadows, and reduced transparency. , even a large piece of dense shadow, can also have the manifestations of atelectasis and blood pneumothorax, blood gas examination can appear abnormal results of varying degrees of weight.

There is a history of exposure to the location of the explosion. According to the investigation, the above symptoms and signs are found. The lung blast injury should be highly suspected. The condition is allowed to be a chest X-ray. You can find that the whole lung has a wide range of opaque spots. Eye shadow; electrocardiogram can detect atrial or ventricular arrhythmia and myocardial ischemia; laboratory examination of hemoglobin and red blood cells decreased due to extensive bleeding in the lungs and gastrointestinal tract, blood oxygenation analysis showed severe hypoxia and acidosis, myocardial enzymes Increased to confirm the diagnosis.

Examination of lung blast injury

1, X-ray inspection

Lungs have thickened lung texture, patchy shadows, reduced light transmission, and even large patches of light, as well as atelectasis and blood pneumothorax.

2, blood gas check

Abnormal results of varying degrees of severity may occur, generally with persistent hypoxemia.

3, physical examination

In addition to the lungs, there may be signs of lung consolidation and blood gas chest signs.

4, chest CT examination

If it appears as a cloud-like shadow with increased density, it suggests alveolar and pulmonary interstitial hemorrhage.

Diagnosis and diagnosis of lung blast injury

According to the history of blast injury, clinical manifestations and X-ray examination, lung blast injury is easy to diagnose, so it is generally not necessary to carry out differential diagnosis, but should pay attention to its external light internal weight, the beginning of light weight, rapid development and often combined injury characteristics The clinical manifestations of lung blast injury are most easily concealed by other external injuries, such as burns, fractures and other more easily diagnosed injuries, so the most important diagnosis of this disease is to distinguish clinical data, and for this type of patients It is necessary to fully consider the existence of lung blast injury and prevent it in time.

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