Pulmonary hyaline membrane disease of newborn (HMD), also known as neonatal respiratory distress syndrome (NRDS), is a disease with a high perinatal prevalence and mortality rate in pediatrics in both developed and developing countries, mostly in preterm infants, caused by a lack of pulmonary surface active substance (PS). The clinical manifestations are progressive dyspnea and respiratory failure shortly after birth, and the pathology is characterized by eosinophilic hyaline membranes on the alveoli and pulmonary atelectasis. Colisol is a natural surface active substance extracted from calf lungs, which compensates for the lack of endogenous alveolar surface active substance in premature infants with RDS and reduces alveolar surface tension. Prolonged mechanical ventilation can lead to chronic lung disease and respiratory tract infections. The combined application of mechanical ventilation and PS for NRDS in our NICU can reduce the amount of PS and decrease the duration of mechanical ventilation.
1.1 Diagnostic basis
Premature infants, with progressive dyspnea or even apnea or respiratory failure soon after birth, have typical lung x-ray changes. According to the criteria of Practical Pediatrics, the chest radiographic changes are classified into 4 grades: grade I: general decrease in translucency (reduced inflation) in both lung fields, with uniformly scattered fine particles (alveolar atrophy) and reticular shadows (fine bronchial hyperinflation); grade II: in addition to the aggravation of grade I changes, bronchial inflation signs (bronchial hyperinflation) are seen, extending to the outer bands of the lung fields; grade III: aggravation of lesions, with more Grade IV: the entire lung field was white. All blood gas tests showed varying degrees of type II expiration. According to the lesions and laboratory tests, congenital pneumonia, neonatal meconium aspiration syndrome (MAS) and other diseases causing respiratory distress were excluded.
1.2 Treatment methods
1.2.1 PS treatment method
Children who have developed NRDS are immediately treated with Colisol without waiting for typical changes in x-ray films. Grade II-III RDS were given PS 70mg/kg each time, with one dose. Grade IV RDS was given 140 mg/kg each time, with one repeat application after 12 h. The airway secretions were firstly aspirated through the tracheal intubation, and Colisol, which had been warmed to 37℃, was aspirated with a sterile syringe and injected rapidly (<1 min) through a thin silicone tube (neonatal gastric tube, the length was fixed first) connected to the syringe in 3 positions (left side, right side and lying down) in 3 times through the tracheal intubation, followed by 2 ml of air with an empty syringe, and then oxygen was administered with a balloon under short time pressure for 3 -5 min, and then connected to a ventilator for ventilation. Aspiration was prohibited for 6 h after each dose.
1.2.2 Mechanical ventilation
Children with varying degrees of type II expiratory failure were ventilated after failure of general oxygen and CPAP or were directly mechanically ventilated due to gestational age <30 weeks, weight <1200 g with moaning, etc. The initial adjustment value varies according to gestational week, weight and condition. In preterm very low weight infants, FiO2 0.~0.8, PIP 16-25 cmH20, PEEP 4-5 cmH20, Ti 0.45-0.6 sec, RR 3O-45 bpm, FR 6-8L/min, intermittent command ventilation (IMV)/end respiratory pressure (PEEP) as the ventilation mode, MAP maintained at 0.8-1.4 kPa to prevent air pressure injury due to high positive pressure. PaO2 was maintained at 6.7 to 10.8 kPa or SaO2 at 0.85 to 0.95 during oxygen therapy to prevent ROP (retinopathy of prematurity).
1.2.3
Other comprehensive measures ① keep warm; ② give total intravenous nutrition during the machine, rehydration according to the gestational week, weight and the severity of respiratory distress symptoms than the normal need to reduce 2O ~ 40ml/kg; ③ are given antibiotics to prevent infection, generally choose a 2nd, 3rd generation cephalosporin or broad penicillin, for suspected pulmonary infection sputum culture in a timely manner, according to drug sensitivity timely adjustment of antibiotics; ④ very low birth weight infants on After several days on the machine, intravenous gammaglobulin, 400-600mg/kg each time, once a week; ⑤ the room is equipped with multifunctional dynamic sterilization machine to disinfect the room air; ⑥ according to the routine care of mechanical ventilation, each time before contact with the child strictly wash hands and disinfection, minimize unnecessary operations, in addition to the clean care of the mouth, eyes, buttocks, exempt from wiping, weighing and other operations, no secretion or secretion as little as possible Aspiration; ⑦ intravenous dopamine 3-5 μg/(kg/min) to maintain effective circulation and blood pressure stability; ⑧ maintain normal blood glucose, electrolytes and acid-base balance; ⑨ routine intramuscular injection of vincristine K11mg once; ⑩ comprehensive monitoring measures.
1.3 Observation indexes
Observe the changes of skin color, transcutaneous oxygen saturation and symptoms and signs before and after treatment, and measure the changes of arterial blood gas 15 min before treatment and 30 min, 6 h, 12 h, 24 h and 72 h after treatment or monitor at any time according to the condition. X-ray chest films were taken 0.5 h before treatment, 24 h and 72 h after treatment, blood glucose was measured once to four times a day, electrolytes were measured once a day, and in cases of suspected pulmonary infection, blood routine and CRP were measured before and after treatment, and secretion or blood culture and drug sensitivity tests were performed when necessary.
2 Results
2.1 Clinical manifestations
Cyanosis improved significantly 1 h after PS, shortness of breath, moaning, trismus and other symptoms disappeared, respiratory sounds in both lungs increased significantly on auscultation, symptoms and signs decreased, and SpO2 increased to 85%-92%.
2.2 Blood gas changes
After treatment, the children’s PO2 increased and PCO2 decreased compared with that before treatment, and the difference was significant (P<0.05 or P<0.01), and the pH value also increased.
2.4 Regression
The child was stable with FiO2 < 0.5, PIP < 16-18 cmH20, RR ≤ 15 bpm, PEEP 2-3 cmH20, and blood gases maintained normal for 1 to 2
After 1 to 2 d, the machine was withdrawn and switched to hood oxygen administration (FiO2 0.5-2.0 L/min), and after 1 to 4 h, the oxygen was switched to a warm box until the oxygen was stopped and over to normal breathing, and the time the child was on the machine was significantly shortened and the complications were significantly reduced.
3 Discussion
3.1 The therapeutic effect of PS and mechanical ventilation on RDS PS replacement therapy is an effective method for NRDS, and the data of this group show that the combined application of PS and mechanical ventilation can achieve more satisfactory clinical efficacy.PS has the effect of reducing alveolar surface tension, which contributes to the opening of atrophied alveoli, and the ventilator, through IMV/PEEP mode, keeps the alveoli open at the end of expiration and increases the functional residual air volume, thereby reducing the amount of alveolar surface active material. thereby reducing the consumption of alveolar surface active substances. The combined application of the two methods maintains adequate gas exchange throughout the respiratory cycle, more effectively improving pulmonary oxygenation and improving lung compliance. The combination of the two methods can maintain adequate gas exchange throughout the respiratory cycle, more effectively increase pulmonary oxygenation and improve pulmonary compliance.
3.2 Complications
Compared with the conventional mechanical ventilation group, the morbidity and mortality rate of children with combined PS and mechanical ventilation was significantly lower, and the complication rates of pneumonia, intracranial hemorrhage, and pneumothorax air leak were lower than those reported by Li J et al. It should not be used only when typical RDS changes appear on x-ray. Prophylaxis with PS can be considered for those <30W of age and <1200g of birth weight. PS is given to inflate the alveoli first, and then ventilated by ventilator IMV/PEEP to evenly distribute PS to the alveolar surface, giving full play to its physiological effects, maintaining adequate gas exchange between the inspiratory and expiratory phases, and improving the oxygenation function of the lungs and the production of PS by the alveoli themselves. The lungs of preterm infants develop rapidly after birth, but the PS produced in the second and third d after birth cannot maintain normal respiration, and the synthesis and secretion of PS increases naturally after 3 d, reaching normal levels in 4 to 5 d. Therefore, the lack of stage to supplement PS, maintain effective respiration, so that premature infants through the respiratory difficulties, their survival rate can be greatly improved; ② strengthen comprehensive treatment measures to maintain cardiovascular function and the stability of the internal environment, the application of antibiotics to prevent infection, the use of gammaglobulin to enhance immunity and a series of effective disinfection management measures to greatly reduce lung infections; ③ strengthen monitoring and surveillance to reduce BP, PaO2 fluctuations in BP, PaO2, blood glucose, electrolytes and blood osmolality, and reduce unnecessary medical and nursing operations can reduce the occurrence of intracranial hemorrhage, etc.; ③After using Colisol, once the blood gas improved, the ventilator parameters were adjusted downward in time to prevent pressure injury.
3.3 Hospitalization time and cost
The limited availability and high cost of PS drugs have limited its routine use and repeated application to some extent. However, because the application of PS combined with mechanical ventilation for the treatment of NRDS resulted in significantly less time on the machine, oxygen therapy, and average length of stay than mechanical ventilation alone, and significantly fewer complications, its total hospitalization costs were reduced instead. In conclusion, children with NRDS are mainly due to immaturity of type II alveolar epithelial cells, the production and release of PS within 72 h after birth cannot meet the requirements of respiration, and the exogenous supply of PS is easily inactivated by the presence of a variety of substances such as protein ooze in the alveoli, and with respiratory depletion soon after the symptoms may re-exacerbate, often requiring larger doses and repeated doses to maintain the efficacy, but PS The early use of a sufficient amount of PS, that is, after prong mechanical ventilation to make PS fully effective, improve lung oxygenation and compliance to form a virtuous circle, complementary advantages, both to reduce the repeated use of PS, but also to shorten the time of mechanical ventilation, oxygenation time and x-ray chest film back to normal time. The combination of PS and mechanical ventilation in the treatment of neonatal pulmonary hyaline membrane disease is an effective and affordable treatment method.