1、Neonatal Hyaline Membrane Disease (HMD)新生儿肺透明膜病新生儿肺透明膜病 Ling Chen NICU, Dept of Pediatrics, Tongji Hospital,HUSTWhat is HMD?also called,Neonatal Respiratory Distress Syndrome (NRDS)-新生儿呼吸窘迫综合征新生儿呼吸窘迫综合征一一. Introduction Incidence The incidence is inversely proportional to The incidence is inversely p
2、roportional to the GA and birthweight. the GA and birthweight. The incidence and severity of RDS are The incidence and severity of RDS are expected to decrease after the increase in expected to decrease after the increase in use of antenatal steroids.use of antenatal steroids. Survival has improved
3、with the use of Survival has improved with the use of exogenous surfactant in recent years.exogenous surfactant in recent years.incidence Less than 28 w: 50%80% 32 to 34 w: 15%30% after 34 w: about 5% Rarely at full term infants体重最轻体重最轻美国/22周/280g胎龄最小胎龄最小德国/15周/300g二二. Etiology and PathophysiologyWh
4、at causes HMD? Who are affected by HMD?Pulmonary Surfactant (PS)-肺表面活性物质肺表面活性物质Keep the lung alveoli openStart synthesis in fetus at about 20w by lung type II alveolar cellsProduce lower, before 35wIncrease to adult level after 37d of birthhalf-life 1224hproduced naturally in the lungs to keep the l
5、ung alveoli open. Alveoli without PSAlveoli withPSSurfactant CompositionProtein (SP-A,B,C,D ) 11.1% Total lipid 88.1% Phosphatidylcholine 胆碱胆碱 77.81% (62.9% Lecithin 磷脂酰胆碱磷脂酰胆碱/) Phosphatidylethanolamine 乙醇胺乙醇胺 5.2% Cholesterol 胆固醇胆固醇 8.4% Sphingomyelin 鞘磷脂鞘磷脂 1.5% Lysophosphatidylcholine 溶酶体胆碱溶酶体胆碱
6、 0.9%In mature lung, Phospholipid / Sphingomyelin (L/S) 2Function of PSdecrease alveolar surface tension ( lung compliance), and reduces respiratory work inflationfunctional residual capacity (功能残气量）increase oxygenation增加氧合improve ventilation/perfusion促进通气anti-inflammation抗炎作用EtiologyPulmonary Surfa
7、ctant Increased Risk Decreased Risk Prematurity 早产早产Maternal diabetes 糖尿病母亲糖尿病母亲Cesarean delivery without laborPerinatal asphyxia 窒息窒息Chorioamnionitis 绒毛膜羊膜炎绒毛膜羊膜炎 Multiple gestation 多胎多胎Caucasian, male sex 白种人，男性白种人，男性Familial predispositonChronic intrauterine stress Prolonged rupture of membranes
8、Maternal hypertensionIUGR/SGA 宫内生长迟缓Antenatal maternal steroids use母亲产前使用激素Thyroid hormone Lung type II cells is immature in small preterm infant. Type II cells are sensitive to and decreased by asphyxial insults in the perinatal period. The maturation of type II cells is delayed in the presence of
9、fetal hyperinsulinemia (高胰岛素血症）, and enhanced by the administration of antenatal corticosteroids （and by chronic intrauterine stress such as Preterm infants often have immature lungs with inadequate PSEtiology and PathophysiologyF Pulmonary immaturity results in surfactant deficiencyF Alveoli collap
10、se at the end of expiration leads to respiratory failureF Surfactant deficiency may arise after asphyxia, shock and acidosisalveolar surface tension is higherDiminished PSPulmonary atelectasisImpaired gas exchange(hypoxia and acidosis)Pulmonary artery hypertensionRightto-left shuntingPulmonary capil
11、lary leaked proteinForming hyaline membrane嗜伊红透明膜嗜伊红透明膜肺透明膜病肺透明膜病发病机理发病机理 肺泡表面张力肺泡表面张力PS PS 缺乏缺乏肺泡不张肺泡不张缺氧、酸中毒缺氧、酸中毒肺动脉高压，肺动脉高压，PDAPDA肺间质水肿肺间质水肿纤维蛋白沉着纤维蛋白沉着于肺泡内表面于肺泡内表面气体弥散障碍气体弥散障碍 肺泡萎陷、肺顺应性肺泡萎陷、肺顺应性 潮气量、通气量潮气量、通气量 肺泡通透性增加肺泡通透性增加 Alveolar Surface Tension Leads to AtelectasisLung compliance decreased
12、. Functional residual capacity decreased.Lung volume reduced. Alveolar ventilation decreased Airway resistance remains normal肺顺应性气道阻力功能残气量三三. Pathology Gross the lung collapsed, firm, dark red, and liver-like. decreased lung volumeNormal alveoliRDS: Atelectasis, pulmonary edema, collapsed alveoli fi
13、ll with fibrin, cellular debris and hyaline membraneRDS: hyaline membranes 四四. Clinical Manifestation Clinical PresentationF Respiratory distress respiratory failure occur in first few hours of age and gets progressively worse -生后进行性呼吸困难生后进行性呼吸困难 Tachypnea RR 60 bpm， Cyanosis (increased need to oxyg
14、en)chest retractions - - 三凹征三凹征nasal flaring - - 鼻扇鼻扇 expiratory grunting - - 呻吟呻吟 Features of HMD respiratory failure occur at or soon after birth, not longer than 12 h; the symptoms usually peak on the third day when diuresis starts, the symptoms can resolve quickly by PS use .F Circulatory insuff
15、iciency PDA HypotensionHypotension Congestive heart failure due to left-to-right shunting during recovery ShockF Intracranial HemorrhageF Others: pulmonary hemorrhage, pulmonary infections complications of assisted ventilationemphysema, pneumothorax, ventilator-associated pneumonia，BPD- Complication
16、sRadiographic Changes1. bell-shaped thorax ( less volume lung )2. the lungs are hypoaerated 低低透亮度透亮度 bilateral,diffuse,homogeneous reticulogranular opacities 弥漫、均匀的网状颗粒影弥漫、均匀的网状颗粒影3. air bronchograms- peripherally extending 支气管充气征支气管充气征4. unclearness of the cardiac/diaphragmatic silhouette 心脏、横隔轮廓不清
17、心脏、横隔轮廓不清，or white lung 白肺白肺Classic respiratory distress syndrome (RDS). Moderate NRDS. The reticulogranular pattern is more prominent. The lungs are hypoaerated. peripherally extending air bronchograms are present. Severe respiratory distress syndrome (NRDS). Reticulogranular opacities, prominent a
18、ir bronchograms, total obscuration of the cardiac silhouette. Complication of respiratory distress syndrome (RDS). a right tension pneumothorax with herniation of right upper lung across midline. pneumomediastinum Laboratory FindingsF Blood gas analysis: hypoxemia, hypercapnia, and respiratory acido
19、sis F Phospholipid (PL)/ Sphingomyelin (S) 0.6, PaO250mmHg or TcSO285% Pressure: 410cmH2O, flow 5L/min, 32C, humidity 100%F Mechanical Ventilation (CMV) Indication: 1.PaO250mmHg or TcSO270mmHg 2.CPAP failure 七七. Prevention Avoidance of preterm birth and asphyxia In preterm birth, to assess lung matu
20、rity by bobbles test The use of antenatal maternal steroids if GA34w, bubbles (-) Preventive use of surfactant at the first 6 h of birth to some babies at very high risk for RDS Most effective way is to prevent preterm delivery. If preterm delivery is inevitable, attempts to “mature the fetus” are reasonable. The incidence of HMD decreased by use of antenatal maternal steroids: 34 weeks of gestation, rate is about 5%. Maternal steroids during preterm labour can prevent HMD in manyThank for your attention !
