Pulmonary edema in children

Introduction to pulmonary edema in children Pulmonary edema (pulmonaryedema) is a pathological condition in which extrapulmonary fluid increases. The serous fluid leaks or exudes from the pulmonary circulation. When the lymphatic drainage capacity is exceeded, excess fluid enters the pulmonary interstitial or alveolar space and forms pulmonary edema. The disease can be complicated by a variety of diseases, the condition is often critical, and should be actively rescued. basic knowledge The proportion of illness: the incidence rate of infants and young children is about 0.001%-0.002% Susceptible people: infants and young children Mode of infection: non-infectious Complications: respiratory acidosis

Causes of pulmonary edema in children

Increased hydrostatic pressure in the pulmonary capillaries (20%):

That is, hemodynamic pulmonary edema, the most important cause of pulmonary edema, can be seen in the following cases:

(1) Excessive blood volume: such as blood transfusion, excessive infusion, too fast, especially children with cardiopulmonary dysfunction or severe anemia, and excessive secretion of antidiuretic hormone (such as severe pneumonia and asthma) and drug effects .

(2) left ventricular dysfunction: insufficient blood flow, resulting in increased left atrial diastolic pressure, seen in any type of left heart failure, including arrhythmia, cardiomyopathy, severe aortic stenosis, mitral valve disease, acute glomerular Nephritis and so on.

(3) The negative pressure value in the pleural cavity is too large: the pressure gradient of the pulmonary capillary cross-wall increases, which is found in the negative phase of intermittent positive pressure ventilation, that is, when the airway pressure is lower than the atmospheric pressure, the pulmonary interstitial abnormality increases the negative pressure, which is more common in Rapidly pumping a large amount of pleural effusion or pleural cavity gas causes the lungs to swell too fast, and the negative pressure in the pleural cavity is too large, so that the fluid flows from the pulmonary capillaries to the interstitium. Some people call it a recurrent pulmonary edema. It was confirmed that the mitochondrial superoxide dismutase and cytochrome oxidase were decreased in the collapsed lung tissue, and when the lung was re-expanded, the production of oxygen free radicals increased, leading to damage of lung epithelial cells and endothelial cells and pulmonary edema.

(4) Others: Excessive pulmonary blood flow can cause a sharp rise in pulmonary capillary pressure, seen in left to right intracardiac shunt, anemia, etc.

Plasma protein osmotic pressure decreased (20%):

Found in severe liver disease, kidney disease and severe hypoproteinemia, pulmonary edema occurs in renal failure, and is associated with changes in capillary permeability.

Increased pulmonary capillary permeability (20%):

Also known as toxic pulmonary edema or non-cardiogenic pulmonary edema, capillary endothelial damage can be caused by many causes, common fulminant pulmonary edema, such as endotoxin, inhaled gastric acid or other acids, inhaled nitrogen dioxide, chlorine, phosgene, High concentration of oxygen or other toxic gases, or shock lungs, characterized by increased permeability, protein into the stroma and alveolar, a layer of protein is lined in the alveoli, histologically like neonatal respiratory distress syndrome The transparent membrane is clinically characterized by decreased lung compliance and gas exchange disorders.

Lymphatic obstruction (20%):

Lymphatic reflux disorder is also one of the causes of pulmonary edema, but it is rare in many cases. The neonatal wet lung is considered to be due to the delay of the pulmonary lymphatic system to clear the fetal alveolar fluid.

Increased surface tension of the alveolar capillary membrane gas-liquid interface (10%):

If the surface active substance is absent, the surface tension of the alveoli is increased, which promotes the liquid from the blood vessels to the interstitial and then enters the alveoli. The appearance of pulmonary edema can reduce the synthesis of surfactants, increase the surface tension, and make the pulmonary edema worse, showing a vicious circle. .

Other reasons (5%):

There are other reasons for the formation of pulmonary edema.

(1) neurogenic pulmonary edema: seen in head trauma or other brain lesions, the mechanism is unknown, may be alveolar capillary permeability increased, may also be due to hypothalamic dysfunction, central sympathetic nerve excitation, peripheral vasoconstriction, lung Increased blood volume, caused by elevated pulmonary capillary pressure.

(2) high altitude pulmonary edema: may be due to pulmonary hypertension, may also due to mechanical extension of the vascular endothelium, causing increased permeability and leakage of plasma proteins, may also increase pulmonary capillary permeability due to hypoxia, patient lung lavage A large amount of high molecular weight proteins, red blood cells and white blood cells can be seen in the liquid.

(3) Gram-negative bacterial sepsis: pulmonary edema may be caused by endotoxin damage to alveolar epithelial cells, pulmonary vasoconstriction and capillary hydrostatic pressure increase, but more importantly due to increased capillary permeability, as seen in shock lung.

(4) Respiratory obstruction: such as bronchiolitis and asthma, may be due to increased intrapleural pressure, alveolar hypotonic pressure and pulmonary interstitial negative pressure, increased pulmonary capillary pressure and increased permeability leading to pulmonary edema, water into Too much quantity can promote its occurrence.

There is a disorder in the exchange and operation of fluid between the blood vessels and tissues in the lungs, causing fluids and proteins to ooze out from the blood vessels, and beyond the clearing ability of lymphoid tissues, excessive liquid sputum accumulates in the lung tissues, which is pulmonary edema.

Pathogenesis

The basic reason is that the balance between hydrostatic pressure difference (cross-wall pressure difference) and colloid osmotic pressure difference of pulmonary capillaries and interstitial is destroyed; in recent years, it is considered that alveolar capillary membrane permeability is also very important, liquid passage The transcapillary filtration of fluid (FF) can be expressed by the following formula: FF=K[(Pcap-Pis)-(cap - is)] K is the filtration coefficient, including the surface of the pulmonary capillary membrane Area and permeability, Pcap is the hydrostatic pressure in the pulmonary capillaries [normally about 1.3 kPa (10 mmHg)], Pis is the interstitial hydrostatic pressure [normal value is unknown, generally considered to be about -1.3 kPa (-10 mmHg) ], is the reflection coefficient, indicating the pressure difference across the capillaries, reflecting the resistance of the membrane to protein flow, generally 0.8, cap is the colloid osmotic pressure in the pulmonary capillaries (normally about 25mmHg), is is interstitial fluid colloidal penetration Pressure (normal value is unknown, generally considered to be half of plasma osmotic pressure), interstitial hydrostatic pressure and colloid osmotic pressure are not easy to detect, some people think that interstitial hydrostatic pressure is negative, so the liquid from capillary to interstitial Movement; interstitial fluid colloid osmotic pressure is about plasma infiltration Half of the pressure causes the liquid to flow from the interstitial to the blood vessel. The above two pressure differences are combined. As a result, the liquid moves from the capillaries to the interstitial. In addition, the liquid movement is affected by the surface tension of the air-liquid interface of the alveolar capillary membrane. The surface tension of the alveoli promotes fluid from the capillaries to the alveoli, but is generally offset by the alveolar pressure. Therefore, the last force vector causes the fluid to flow from the capillaries to the interstitium, which is then drained by the lymph. This is because of the hydrostatic pressure of the lymphatic vessels. The quality is similar, and the colloid osmotic pressure is higher than the interstitial, so the liquid moves from the interstitial to the lymphatic vessels, and the presence of lymphatic smooth muscle and funnel-like valve and its pumping effect are beneficial to the drainage of interstitial fluid to lymphatic vessels. To prevent pulmonary edema, although the water to the interstitial filtration increases when the hydrostatic pressure of the pulmonary capillaries increases or the plasma colloid osmotic pressure decreases, the liquid begins to accumulate in the interstitial only when the lymphatic drainage is exceeded.

Pediatric pulmonary edema prevention

Pulmonary edema often occurs in the end of various serious diseases, so active prevention and treatment of heart failure such as pneumonia, various heart disease and acute, chronic nephritis, shock caused by various serious infections, organophosphate poisoning, etc. can prevent lung The occurrence of edema.

Pediatric pulmonary edema complications Complications, respiratory acidosis

Respiratory failure can occur due to severe hypoventilation, which can lead to metabolic and respiratory acidosis, alveolar collapse, and even suffocation.

Pulmonary edema symptoms in children Common symptoms Pale pale respiratory acidosis dyspnea cyanosis tachycardia chest pain hypoxemia circulatory failure liver enlargement

Symptoms and signs: onset or acute or slow, chest discomfort, or local pain, dyspnea and cough are the main symptoms, often pale, bruising and sorrowful look, coughing often spit out foamy sputum, and a small amount of blood can be seen At the beginning, the chest signs are mainly found in the lower back of the chest, such as mild dullness and most blisters, gradually develop to the whole lung, the heart sound is generally weak, the pulse rate is weak, and the lesion progresses with puff-like breathing, apnea, peripheral vasoconstriction. , heart skipping and liver enlargement, interstitial pulmonary edema, no clinical symptoms and signs, alveolar edema, lung compliance decreased, the first symptoms are increased breathing, alveolar edema, the above symptoms and signs progress, hypoxia Aggravation, such as rescue can not be timely due to breathing, circulatory failure and death, typical clinical manifestations, such as infants, common breathing increased, chest wall depression, nasal fan, sputum, tachycardia, liver, severe cyanosis, exhalation Progressive respiratory function compensation is incomplete, such as intermittent breath holding, peripheral vasoconstriction and tachycardia, due to alveolar fluid, lung bottom Can be heard and voice, respiratory failure, tissue for O2 deficiency, and finally lead to metabolic and respiratory acidosis, most of the elderly complained of breathing difficulties, or chest pain and depression, cough with red foamy sputum, sometimes like asthma Attack, pale or cyanosis, pulse fast and weak, lungs can have sputum sound or blisters, liver, blood pressure.

Examination of pulmonary edema in children

Blood gas analysis has severe hypoxemia, arterial blood oxygenation, PCO2 can be reduced due to hyperventilation, manifested as respiratory alkalosis, arterial blood PO2 and PCO 2 can be reduced, X-ray examination of interstitial pulmonary edema visible cord shadow Lymphatic vessel dilatation and interlobular septal effusions are characterized by oblique lines of the hilar region and horizontal strips of Kerby A and B lines, alveolar edema with small patchy shadows (Fig. 2), and progression of the disease Multi-fusion in the vicinity of the hilar and at the base of the lungs, forming a typical butterfly-like shadow or bilateral diffuse patchy shadows, resulting in blurred heart shadow, accompanied by inter-leaf and pleural effusion.

Diagnosis and diagnosis of pulmonary edema in children

diagnosis

According to the performance plus X-ray characteristics and hypoxemia, the diagnosis can be generally confirmed.

Differential diagnosis

Pulmonary edema is a serious disease in children, often seen in the end of various serious diseases, such as pneumonia, heart failure caused by various heart diseases and acute, chronic nephritis, shock caused by various serious infections, organophosphate poisoning, etc. Both can cause pulmonary edema, the characteristics of the primary disease and the corresponding medical history can help identify.

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