What is Hyaline Membrane Disease?

Hyaline membrane disease (HMD), also known as idiopathic respiratory distress syndrome or neonatal respiratory distress syndrome (RDS), refers to the progression of progressive atelectasis shortly after birth. Dyspnea, bruising, expiratory moaning, inspiratory tricuspid, and respiratory failure; pathologically characterized by the eosinophilic transparent membrane attached to the terminal bronchioles to the alveolar wall. It is generally found in premature infants. It mainly causes atelectasis due to insufficient surfactants, so it is also called "surfactant deficiency syndrome". It is the most common cause of early respiratory difficulties and death in preterm infants.

Chinese name: Hyaline membrane disease

Foreign name: Hyaline membrane disease
Department: Respiratory Medicine

Causes of hyaline membrane disease

Congenital pulmonary lobular emphysema

Although there are factors of congenital lung developmental disorders, there are also cases of acquired bronchial compression. Therefore, this disease is also called "newborn" pulmonary lobular emphysema or "infant", and should not be called

Lobular emphysema image "Natural" pulmonary lobular emphysema. It is characterized by excessive expansion of a leaf or a section of lung tissue, which compresses normal lung tissues, mediastinal organs, and the cardiovascular system. It is one of the common causes of acute respiratory distress in infants and young children. It is only found in newborns or young children. Of the 1/3 cases that occurred immediately after birth, 50% occurred in 1 month after birth, and only 5% occurred in 6 months after birth. More men than women were more common in the upper lobe of the lungs (most common in the upper left lobe), followed by It is the right middle lobe and the lower lobe is rare. The clinical manifestations are unilobal or unilateral hyaline membrane disease. Theoretically, the abnormality of the lung parenchyma itself is the possible cause of this disease, but it has not been confirmed. Some people have studied the morphology of the lung lobe after resection, which can be seen The number of alveoli increased by more than 50%, and the alveolar size was normal or enlarged, and the number and structure of the trachea and blood vessels were normal, suggesting that this disease is a large alveolar disease or an abnormal increase in alveoli after birth.

Hyaline membrane disease specific emphysema

(Swyer-James syndrome) Swyer and James (1953) first reported the disease as a 6-year-old boy. In 1954, Macleod reported 9 similar patients in adults, so this disease is also called Macleods syndrome or MSJ syndrome. Pathology: mainly manifested as chronic inflammation changes, no bronchial stenosis and obstruction, which is different from congenital pulmonary emphysema; yes Pulmonary arteries are developed and filling, but are smaller. This is different from the absence or development of pulmonary arteries.

Pathogenesis

1. There are many causes and pathogenesis of congenital pulmonary lobe emphysema. This disease may be considered as a clinicopathological syndrome rather than a single lesion. The primary lesion may be in the leaf bronchus (causing partial obstruction). And secondary swelling) or in the lung parenchyma, the former accounts for about 50%, and the incidence factors are divided into 3 categories: extrabronchial compression: about 7% can be caused by multiple reasons. The most common is the abnormal blood vessels,

Abnormal blood vessels Such as large open arterial catheters, abnormally running pulmonary veins or vagus pulmonary arteries (left pulmonary artery originates from the right side), etc., it can also be seen in the abnormally enlarged lymph nodes or the pressure of the bronchial mass (bronchogenic cyst) to force the compressed bronchus Emphysema of the distal lung tissue; abnormal bronchial wall: about 2/3 of the cases are clear or suspected of lack of bronchial cartilage or dysplasia, causing tracheal collapse, obstruction, and secondary obstructive emphysema of the distal lung lobe; Intrabronchial obstruction: may be congenital or acquired, the former including mucosal folds or localized bronchial stenosis, and the latter including mucus plugs or granulation tissue. Reports in the literature: Bronchial cartilage defects or deformation can be seen in 25% to 40% of resected specimens, and the cause is still unknown in more than 50% of cases. 40% to 50% of infants and young children with other deformities, such as: congenital heart disease, cleft palate and so on.

2. Specific emphysema, which is different from congenital lobular emphysema, can be found in children or adults; it can be one leaf or one side of the lung, and is an independent syndrome different from other hyaline membrane diseases. Swyer believes that this disease is Due to the widespread pulmonary disease, the etiology of right pulmonary insufficiency is not clear, it may be related to viral infection or it may be caused by congenital or acquired factors.

Clinical manifestations of hyaline membrane disease

Pulmonary hyaline membrane formation

1. Symptoms of congenital emphysema are divided into two types: early onset and late onset. Only 5% of the patients develop symptoms 6 months after birth, and half of the patients develop respiratory distress in the first month after birth. Few people are asymptomatic. Typical early-onset symptoms start from the fourth day to a few weeks after birth. The symptoms progress very quickly, with progressive dyspnea, inspiratory and expiratory wheezing, tachycardia, cyanosis, etc. Signs are: asymmetry of the thorax, fullness of the ipsilateral thorax, percussion sounding, weakening of breathing sounds, and tracheal and mediastinal shifts similar to pneumothorax. Delayed symptoms are recurrent respiratory infections. Examination: swelling of the ipsilateral thorax, enhanced perusal response and auscultation The sound is reduced, and wheezing or rales may be heard.

2. Specific emphysema can be seen in children and adults. The clinical manifestations are different, and the symptoms can be asymptomatic. In severe cases, cough, sputum, dyspnea or repeated respiratory infections and massive hemoptysis can be seen and congenital lung lobe gas. Swelling is similar.

Diagnosis of pulmonary hyaline membrane disease

Combined with clinical manifestations and X-ray examination, the single-leaf lung translucency can increase the texture of blood vessels, and the vascular texture can be diffused and thinned. For older children with congenital emphysema, bronchoscopy may be performed to exclude intratracheal lesions. An important feature of radiology is that blood vessels can be distinguished from bullae.

Differential diagnosis of hyaline membrane disease

Congenital emphysema should be distinguished from atelectasis. The difference between lobular emphysema and atelectasis and compensatory emphysema lies in the elevation of diaphragm muscle on the affected side and displacement of the mediastinal affected side. Lung translucency increases and the blood vessel texture is significantly diffused and thin, which can be distinguished from bullae according to the blood vessel texture.

Hyaline membrane disease

1. Radiological examination of congenital emphysema shows more common lesions in the upper lobe, with the left side as the main lower lobe. Rarely, it is characterized by increased single-leaf lung lightness, reduced blood vessel texture, and increased volume of the affected leaf. Compression, atelectasis, displacement of the mediastinum on the healthy side, diaphragmatic muscles move down or normal, fluoroscopy shows that the mediastinum moves toward the affected side when inhaled, and exhalation shifts to the healthy side. Occasionally, increased lung density, rather than high light transmission, is due to fluid emptying disorders secondary to bronchial obstruction, but other radiological features are still present, and the fluid can be cleared within 24 hours to 2 weeks. Radiological characteristics (high transmittance) are restored. Specific emphysema X-ray manifestations of increased pulmonary transillumination and reduced hilar vascular texture. Bronchography: bronchial filling at the proximal end, small distal bronchus below level 5-6, seeing: the medial side of the mediastinum is displaced during inhalation, the diaphragmatic muscle activity of the affected side is weakened, and the lung volume does not change with breathing movement

2. Cardiovascular congenital emphysema shows abnormal blood vessels or cardiac malformations. Radionuclide lung scans show reduced blood perfusion in the affected leaves. Bronchoscopy and bronchography are used to exclude other lesions. Pulmonary angiography: Small peripheral blood vessels on the affected pulmonary artery are scarce. Radionuclide examination: significant reduction in lung perfusion.

3. Bronchoscopy examination of bronchial mucosal hyperemia, edema, thickening and other acute and chronic inflammation manifestations.

4. Pulmonary function tests suggest ventilation dysfunction.

Treatment of hyaline membrane disease

CT of hyaline membrane disease

1. Some patients with congenital emphysema relieve symptoms without surgery. Nearly 50% of the non-surgical mortality rate often requires emergency surgery because it seriously affects heart and lung function. Surgery is more dangerous, especially during the period from the beginning of positive pressure ventilation to the removal of the affected lung. Therefore, the chest must be opened as soon as possible and the lungs must be removed as soon as possible. The prognosis after lung resection is good, and the mortality rate is <5%.

2. Conservative treatment of specific emphysema is mainly antispasmodic and anti-inflammatory, which is similar to congenital pulmonary lobular emphysema. Severe symptoms have a good prognosis.

Principles of treatment of hyaline membrane disease

Nasal congestion, continuous positive airway pressure (CPAP), PS, and mechanical ventilation are the ultimate goals of opening the collapsed alveoli, PS is to reduce the alveolar surface tension, CPAP and mechanical ventilation are using PEEP. Pros and cons.

PS replacement therapy is a specific treatment for the cause [3]. However, due to the need for tracheal intubation and high cost, this method is not recommended for moderate to mild children. Another important reason is that tracheal intubation greatly increases the risk of infection.

It is of great significance to apply different treatments to children with different levels of neonatal hyaluromeas. Early treatment with CPAP is sufficient for moderate-to-mild children. If 6 hours after treatment, the blood gas of the child is not significantly improved, cyanosis is still observed, and blood oxygen saturation is less than 85%, then mechanical ventilation and PS treatment will be used. Grade III children should be treated with PS if they are tolerant to the initial CPAP and adhere to CPAP. If there is no improvement, change to mechanical ventilation + PS. For grade IV children, use mechanical ventilation as soon as possible and give PS, or even use it multiple times. .

Treatment of hyaline membrane disease

Oxygen therapy for pulmonary hyaline membrane disease

Oxygen therapy is the main measure to treat the symptoms of hyaline membrane. Early nasal congestion can be used for continuous positive airway pressure (CPAP) treatment with a pressure of 0.392kPa to 0.588kPa. When the inhaled oxygen concentration is 60% to 100% and Pa02 <6.67kPa, PaC02> 8.0kPa, there is no spontaneous breathing or frequent apnea. When the effect of CPAP is not good, you need to apply respirator for intermittent positive pressure breathing (IPPV).

Pulmonary hyaline disease active substance replacement therapy

Lung surface active substance 100mg / kg can be used for intratracheal instillation. The timing, frequency and dose of the application have not been determined. And this medicine can only provide conditions to improve the alveolar opening, but cannot treat the pathophysiological changes of the body that have occurred and developed.

Supportive therapy for hyaline membrane disease

(1) Keep warm: Maintain a neutral ambient temperature to reduce oxygen consumption and keep the abdominal skin temperature at 36.5 ° C.

(2) Maintain nutrition and water-electrolyte balance: those who are severely incapable of oral feeding can use intravenous infusion to maintain the amount of fluid. The daily amount of fluid in the vein should be controlled at about 0g1-80ml of tongue. Can increase the amount appropriately. When the condition is serious and the intake of calories is insufficient, intravenous nutrition should be given, supplemented with amino acid solution and fat emulsion.

(3) Maintain circulation and correct anemia: Dopamine can be given to maintain blood pressure and perfusion of various organs (5ug to 10ug / kg per minute, intravenous drip maintenance). In order to reduce the load on the heart and expand the pulmonary blood vessels to increase the effect of oxygen supply, phentolamine (torazoline, 0.5 mg-1 mg / kg each time, added to a 10% glucose solution and slowly infused, every 4-6 hours Times). Hematocrit can be transfused when the hematocrit is less than 0.40.

(4) Use of antibiotics: to prevent secondary infections.

Pulmonary hyaline disease prevention

Take good care during pregnancy to prevent premature and perinatal hypoxia. For pregnant women who may be born prematurely, use adrenocortical hormones. Give dexamethasone 6mg-10mg once daily, intramuscularly or Intravenous drip. For preterm infants and those with a history of perinatal hypoxia, intravenous dexamethasone lmg-2mg is used to promote the production and release of pulmonary surfactant. ^[1]