Respiratory distress syndrome of newborns

Respiratory distress syndrome of newborns is caused by the lack of surfactant in the lungs of children born in gestational age less than 37 weeks. The risk increases with the degree of prematurity. Symptoms of respiratory distress syndrome include shortness of breath, the involvement of additional muscles in the act of breathing and swelling of the wings of the nose that occur shortly after birth. Diagnosis is based on clinical data; Prenatal risk can be assessed using lung maturity tests. Treatment includes surfactant therapy and maintenance therapy.

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What causes respiratory distress syndrome in newborns?

Surfactant is a mixture of phospholipids and lipoproteins, which are secreted by Type II pneumocytes; it reduces the surface tension of the aqueous film that covers the inside of the alveoli, thereby reducing the inclination of the alveoli to collapse and the work necessary to fill them.

When the surfactant deficiency in the lungs develop diffuse atelectasis, which provokes the development of inflammation and pulmonary edema. Since the blood passing through the areas of the lung with atelectasis does not oxygenate (forming the right intrapulmonary shunt), the child develops hypoxemia. The elasticity of the lungs decreases, so the work expended on breathing increases. In severe cases, the weakness of the diaphragm and intercostal muscles develops, the accumulation of CO2 and respiratory acidosis.

Surfactant is not produced in sufficient quantities until relatively late gestation; therefore the risk of a respiratory distress syndrome (RDS) increases with the degree of prematurity. Other risk factors include multiple pregnancy and diabetes maternal. The risk decreases with fetal hypotrophy, pre-eclampsia or eclampsia, maternal hypertension, late rupture of the membranes and admission of the mother glucocorticoids. Rare causes include birth defects of the surfactant caused by mutations in surfactant protein (BSV and BSS) and ATP binding cassette A3. Boys and whites are at greater risk.

Symptoms of respiratory distress syndrome

The clinical symptoms of respiratory distress syndrome include rapid breathing movements with wheezing and wheezing that occur immediately after the birth of the child or within a few hours after childbirth, with the retraction of the pliable areas of the chest and the swelling of the wings of the nose. With the progression of atelectasis and respiratory failure, manifestations become more severe, cyanosis, inhibition, irregular breathing, and apnea.

Children with birth weight less than 1000 g can have so rigid lungs that they are unable to start and / or maintain breathing in the rod.

Complications of respiratory distress syndrome are intraventricular hemorrhage, periventricular damage to white matter of the brain, intense pneumothorax, bronchopulmonary dysplasia, sepsis and death of a newborn. Intracranial complications are associated with hypoxemia, hypercapnia, hypotension, fluctuations in blood pressure and low perfusion of the brain.

Diagnosis of respiratory distress syndrome

The diagnosis is based on clinical manifestations, including the definition of risk factors; gas composition of arterial blood, demonstrating hypoxemia and hypercapnia; and chest radiography. On the chest X-ray, diffuse atelectasis is seen, classically described as a kind of frosted glass with noticeable air bronchograms; X-ray picture is closely related to the severity of the flow.

Differential diagnosis is performed with pneumonia and sepsis caused by group B streptococcus, transient tachypnea of newborns, persistent pulmonary hypertension, aspiration, pulmonary edema and congenital pulmonary-cardiac anomalies. As a rule, in patients it is necessary to take blood, liquor and, possibly, aspirate from the trachea. It is extremely difficult to clinically diagnose streptococcal (group B) pneumonia; so usually in anticipation of the results of crops begin antibacterial therapy.

The possibility of developing a respiratory distress syndrome can be assessed prenatally using lung maturity tests, in which the surfactant obtained from amniocentesis or taken from the vagina is measured (if the fetal membranes have already ruptured). These tests help determine the optimal time for delivery. They are shown in separate births before the 39th week, if fetal heart tones, levels of chorionic gonadotropin and ultrasound can not confirm the gestational age, and at all births between the 34th and 36th weeks. The risk of developing respiratory distress syndrome is lower if the lecithin / sphingomyelin ratio is more than 2, phosphatidyl inositol is present, the foam stability index is 47 and / or the surfactant / albumin ratio (measured by the fluorescent polarization method) is more than 55 mg / g.

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Treatment of respiratory distress syndrome

Respiratory distress syndrome in treatment has a favorable prognosis; lethality less than 10%. With adequate respiratory support, surfactant products begin to develop over time, with respiratory distress syndrome resolved within 4-5 days, but severe hypoxemia can result in multiple organ failure and death.

Specific treatment consists of intra-tracheal administration of surfactant; it is necessary to intubate the trachea, which may also be necessary to achieve adequate ventilation and oxygenation. Less preterm infants (more than 1 kg), as well as children with a lower requirement for oxygen (O [N] fraction in the inhaled mixture less than 40-50%) may be sufficient only for support 02

Surfactant therapy accelerates recovery and reduces the risk of pneumothorax, interstitial emphysema, intraventricular hemorrhage, bronchopulmonary dysplasia, and hospital mortality in the neonatal period and at 1 year. At the same time, infants who received surfactant for respiratory distress syndrome are at a higher risk of developing apnea of prematurity. Opportunities for substitution of surfactant include the attackant (fatty extract of bovine lungs supplemented with proteins B and C, colfosceril palmitate, palmitic acid and tripalmitin) at a dose of 100 mg / kg after 6 hours if necessary up to 4 doses; alpha-podactan (modified extract of ground pork lungs containing phospholipids, neutral fats, fatty acids and proteins B and C) 200 mg / kg, then up to 2 doses per 100 mg / kg if necessary after 12 hours; calfactant (an extract of light calves containing phospholipids, neutral fats, fatty acids and proteins B and C) 105 mg / kg in 12 hours to 3 doses, if necessary. The elasticity of the lung can quickly improve after the administration of the surfactant; To reduce the risk of a syndrome of air leakage from the lungs, you may need to quickly reduce peak inspiratory pressure. Other parameters of the ventilator (FiO2 frequency) may also need to be reduced.

How to prevent respiratory distress syndrome?

If the delivery should occur at the gestation period of 24-34 weeks, the appointment of the mother 2 doses of betamethasone 12 mg with a break of 24 hours or 4 doses of dexamethasone 6 mg intravenously or intramuscularly after 12 hours at least 48 hours before the birth stimulates the formation of surfactant in the fetus respiratory distress- the syndrome develops less often or reduces its severity.