Neonatal respiratory distress syndrome Causes

Causes of Neonatal respiratory distress syndrome is the lack of pulmonary surfactant (PS). Because of alveolar and air interface have surface tension, if the lack of surfactant, alveoli are compressed, and has gradually formed atelectasis, increasing its scope. Atelectasis flow through the region, without the exchange of gas and back to the heart to form a short-circuit the lungs. Therefore blood PaO2 decreased oxygenation decreased only in the hypoxic metabolism in vivo conditions, resulting in acidosis. acidosis of pulmonary vasospasm, pulmonary vascular resistance increased, so that increased right ventricular pressure. Sometimes patent ductus arteriosus can re-opening to form a right-to-left shunt. In severe cases, 80% of cardiac stroke volume as a sub-flow, cause obvious bruising in infant. Into the pulmonary blood flow reduction in lung volume of the reperfusion, the blood vessel wall permeability increase that caused by hypoxia, and plasma extravasation, including proteins. The exudate formed hyaline membrane because of calm and collected fibrin.

Risk factors of Neonatal respiratory distress syndrome (NRDS):

1. Premature Infant:
Fetus in the 22 ~ 24 weeks gestational age when alveolar type Ⅱ cells have been able to have a PS, but very few, and rarely transferred to the alveolar surface, with the growth of age, PS Synthesis of a gradual increase, so the more premature infants lungs the amount of PS less, RDS also the higher the incidence. 24 ~ 30 weeks gestational age, when a variety of hormones to promote the role of the largest lung maturation, antenatal prevention at this time is the best stage, 32 ~ 34 weeks after the hormone on the impact of lung maturity is not very important, after 35 weeks gestational age is rapidly entering the alveolar surface of PS phase. preterm infants after birth continues to lung development, after birth within 72 ~ 96 hours of the PS have generally able to maintain normal breathing, so as long as PS to add to the lack of stage, so to tide over their difficulties in premature infants, the survival rate to be raised.

2. Infant of diabetic pregnant women:
High blood sugar in diabetic pregnant women, fetal blood glucose also increased fetal insulin secretion at this time must be increased so as to adapt to the needs of glucose metabolism, so that glucose into glycogen. Such situations, the fetus looks great obesity, but lung may not be mature, and insulin have antagonistic role of corticosteroids affect the development of the lung.

3. Intrauterine distress and birth asphyxia:
Intrauterine distress occurred in the fetal placental dysfunction, hypoxia as a result of long-term effects of fetal lung development, PS low secretion; birth asphyxia is often caused by dystocia, It is one of the NRDS cause.