Download Respiratory Distress Syndrome ( RDS )

Neonatal Respiratory Distress
Syndrome (NRDS )
Purpose
 To be familiar with etiology and
mechanism
 To master clinical manifestation and
differential diagnosis
 To master prevention and treatment
Introduce
 NRDS is primarily developmental
deficiency in the amount of
pulmonary surfactant (PS) , at the
air-liquid interface of the lung
 RDS also called hyaline membrane
disease (HMD)
Introduce
 RDS is a disease primarily of the
premature infant
 Pulmonary hyaline membranes and
atelectasis are findings at autopsy
Etiology and Mechanism
 PS produced and released by type II
alveolar cells
 PS appears after 18-20 weeks of GA
 Mature levels of PS are usually present
after 35 -36weeks of GA
Surfactant production and composition
Protein (include SP-A,B,C,D)
Total lipid
13%
80%
Phosphatidyl choline
(also called lecithin)
Phosphatidylglycerol
Sphingomyelin
Others: Cholesterol
Lysophosphatidylcholine
Lecithin/ Sphingomyelin (L/S): an important index of maturation
of lung (amniotic fluid)
Function of PS
 PS cover the surface of alveolus
 degrade the alveolar surface tension to prevent
detelectasis of alveolus
 stabilize pulmonary alveolar pressure
 prevent fluid exudation from blood capillary to
alveolus.
Surfactant(mcg/100g)
30
Surfactant and maturity
20
10
0
24
27
30
33
36
Gestationsal age(weeks)
39
Normal lung
RDS
PS ↓ → surface tension↑ → atelectasis →
hypoxia and acidosis → pa vasoconstriction →
right–to-left shunting → ischemic injury to
the vascular bed of lung→ effusion of
proteinaceous material → pulmonary hyaline
membrane→ hypoxia and acidosis ↑↑
Who Is Risk baby?
 Preterm infant
 Majority of neonates with RDS are
preterm infants.
 The incidence is inversely proportional
to gestational age（GA）
Who Is Risk baby?
Infants of diabetic mothers (IDM)
promote
Glucocorticoid
synthesis of PS
restrain
High concentration of insulin
 Synthesis of PS decrease when PH, temperature and
pulmonary blood volume of body decrease.
asphyxia in perinatal period, low temperature, mother with
hypotension, placental abruption, placental previa, etc may induce
NRDS.
Clinical Manifestations
1. The infant with RDS is mostly
premature
2. Respiratory distress usually occur
and represent progressive worsening
within 6 hours after birth
Clinical Manifestations
Manifestatons of respiratory distress
 Tachypnea: increase ventilatory capacity
 Flaring of alaenasi
 Expiratory grunt
 Three depression sign when inspiration
Clinical Manifestations
Manifestatons of respiratory distress
 Cyanosis
 Severe case presents shallow respiration, respiratory
rhythm irregular, apnea.
 Physical examination: thin and flat of bony thorax,
respiratory sound is weak, fine moist rales when
exudation in alveolus.
Clinical Manifestations
3.Patent ductus arteriosus (PDA):
with recovery of patient’s condition,
pulmonary pressure decrease, about
30%of patients present PDA.
If patient’s condition of NRDS is
obviously improved, sudden present
demand for oxygen increasing,
metabolic acidosis difficult corrected,
difficult feeding, apnea, and continuous
machinery murmur, like rolling thunder
on L 2nd intercostal space can be heard,
PDA should be considered.
4. The clinical manifestation is progressive
worsening.
Uncomplicated
cases
are
characterized by worsening of the disease for
2～3 d with recovery at 72 hr
5. If respiratory distress occur after 12hr, NRDS
should not be considered commonly.
Auxiliary examination
laboratory examination
X-ray
laboratory examination
 Gastric fluid oscillation test (foam test)
 Fetal lung maturity
mensuration L/S of amniotic fluid
L/S ≥2
fetal lung maturity
L/S 1.5~2 doubt
L/S<1.5
immaturity
X-ray
Ground glass
air bronchogram
white-out lung
pulmones present universalistic
permeation decrease
a fine reticular granularity
of the parenchyma
universalistic alveolus atelectasis
aerated bronchus clear display
the whole lung field is white
Treatment
一. Specific therapy
1. Surfactant replacement
such as Survanta, Exosurf , Curosurf
 PS should be given under conditions of
mechanical ventilation.
adequate
 PS should be given as soon as diagnosis, within 24hr,
through trachea, 2-4times according to disease.
Before PS given
After PS given
2.Continuous positive airway pressure (CPAP)
Indication:FiO2(fraction of inspiratory oxygen)>0.4,
PaO2<50mmHg or TcSO2<90%.
CPAP may be administered by nasal prongs, veil,
tracheal intubation
3. mechanical ventilation
Indication:
⑴FiO2=0.6, PaO2<50mmHg or TcSO2<85%(exclude
congenital heart disease).
⑵PaCO2>60-70mmHg and PH<7.25
⑶severe or drug ineffective apnea
4.Closure of the patent ductus arteriosus（PDA ）
 Limit volume of fluid
 indomethacin , 0.2mg/kg.time, at 0,12, 36hr after
diagnosis.
 Surgery
二 . Supportive management
1. Maintain a neutral thermal temperature
2. Administer adequate fluids and electrolytes,
prevent fluid overload.
3. Correct acid-base disturbances
4.oxygen
modus:
nasal catheter
veil
head net
monitor FiO2(fraction of inspiratory oxygen)
keep PaO250～70mmHg and TcSO2 90%～
95%（transcutaneous oxygen saturation）
5. antibiotic
principle: shouldn’t be used. If infection of
newborn occur, antibiotic should be used.
Prevention
1. Prevent premature labor
2.Predict the risk of RDS by testing of amniotic
fluid ： ( L/S >2.0 ), indicates fetal lung
maturity
3.Accelerate fetal lung maturation
Administration of Dexamethasone to
women 48hr before delivery
4. Administration PS
If infant is preterm (24~34week of GA), PS
should be given within 30 min, not more
than 24hr after birth.
Differential diagnosis
1. Meconium pneumonitis（胎粪性肺炎）
Gestational age Full term infant
Etiology
Hypoxia
History
Meconium –stained amniotic fluid
Clinical
manifestations
Signs appear quickly after birth,
barrel-shaped chest, Prolonged expiration,
and rales may be audible.
Hyperinflation, irregular, streaky densities
with areas of atelectasis, Pneumothorax
Radiologic
features
Differential diagnosis
2.Wet lung (transient tachypnea of newborn, TTN)
Gestational age
Etiology
fullterm infant
absorption of amniotic fluid delay
Clinical manifestations
tachypnea after few hours
(>60~80time/min)
feeding well
crying aloud, reflex good
Radiologic features
Hyperinflation
Lung markings increase, patch shadow
symptomatic treatment
recovery after 2-3days.
3. Infectious
pneumonia
Gestational age Each Gestational age
Etiology
Bacteria, virus and other microbe
History
Infection, Prolonged rupture of
membranes, URI
Clinical
manifestations
May occur at any time with nasal
obstruction, coughing, Tachypnea
Radiologic
features
The sign is indefinite
Pneumonia