surfactant replacement therapy : rds & beyond
TRANSCRIPT
Presented By Dr. Hasen Ali Mia 2nd yr PGT ,NBMCH
Chairperson Prof. Sankar Das Dept. Pediatrics,NBMCH
SURFACTANT REPLACEMENT THERAPY : RDS & BEYOND
CONTENTS1. What is surfactant ?
2. Composition of
surfactant
3. Functions & MOA of
surfactant
4. Types of surfactant
5. Timing of administration
6. How to administer ?
7. Complications of
surfactant therapy
8. Indications &
Contraindications
9. SRT in RDS
10. SRT beyond RDS
Multicomponent complex of several phospholipids, neutral lipids, and
associated proteins.
Synthesized and secreted by Type II epithelial cells (pneumocytes) within
the lung.
Reduces collapsing force in the alveolus, conferring stability and maintaining
alveolar surface free of liquid.
Production begins from 16 wks GA onwards ,appears in AF between 32-36
wks, optimum conc. in alveoli beyond 35 wks.
WHAT IS SURFACTANT ?
COMPOSITION OF SURFACTANT
Decrease the surface tension
Promotes lung expansion during inspiration
Prevents alveolar collapse and loss of lung volume at the end of expiration
FUNCTIONS OF SURFACTANT
Molecular forces of the water molecules in the
alveolar lining result in high surface tension
The hydrophilic and hydrophobic properties of
DPPC result in a head-to-tail orientation in the
air-liquid interface inside the alveolus.
Decrease in surface tension of the liquid lining,
MECHANISM OF ACTION
MECHANISM OF ACTION…..
TYPES OF SURFACTANT & DOSAGE
TIMING OF ADMINISTRATIONAt risk baby born
Surfactant given at < 15 min age before respiratory distress=
“Prophylactic”
Signs of RDS develop
Nevertheless, if baby develops signs of RDS
Multiple doses
Described as part of “prophylaxis” regime
If baby continues to have signs of RDS
Multiple dosesDescribed as part of “rescue” regime
Surfactant given at <2 hrs, after resp distress starts but before obvious HMD =
“Early rescue”
Surfactant given at >2 hrs, after obvious HMD =
“Late rescue” or “Selective”
INDICATIONS Prophylactic : Premature infants at high risk of developing RDS secondary to surfactant
deficiency (e.g., <32 weeks or LBW <1,300 g)
Laboratory evidence of surfactant deficiency such as L/S ratio <2:1, bubble
stability test indicating lung immaturity, or the absence of
phosphatidylglycerol
Rescue or therapeutic administration : Preterm or full-term Infants suspected of having surfactant deficiency
and
Who require endotracheal intubation and mechanical ventilation secondary to
respiratory failure and
Who require an FIO2) ≥0.40, and
Clinical and radiographic evidence of neonatal RDS or MAS,
Neonates with MAP >7 cm H2O to maintain an adequate PaO2, SpO2
INDICATIONS……
The presence of congenital anomalies incompatible with life beyond the
neonatal period.
Respiratory distress in infants with laboratory evidence of lung maturity.
Patient hemodynamically unstable.
Active pulmonary haemorrhage.
CONTRAINDICATIONS
Administration of surfactant replacement therapy is strongly recommended in a clinical setting where properly trained personnel and equipment for intubation and resuscitation is readily available.
Prophylactic surfactant administration is recommended for neonatal RDS in which surfactant deficiency is suspected.
Rescue or therapeutic administration of surfactant after the initiation of mechanical ventilation in infants with clinically confirmed RDS is strongly recommended.
A multiple surfactant dose strategy is recommended over a single dose strategy.
Natural exogenous surfactant preparations are recommended over
laboratory derived synthetic suspensions at this time.
RECOMMENDATIONS
INSURE (Intubation, Surfactant, Extubation) technique:
Early surfactant replacement therapy with prompt extubation to nasal CPAP.
A/w less need for mechanical ventilation,
lower incidence of BPD, and
fewer air leak syndromes,
when compared with later, selective surfactant replacement therapy,
mechanical ventilation, and extubation from lower ventilator settings.
How to administer ?
INSURE technique
Pharyngeal instillation before first breath
Laryngeal mask airway (LMA) administration
Bronchoalveolar lavage
Aerosolized surfactant
Other modes:
Proper placement and position of delivery device and ETT
FIO2 and ventilator settings
Reflux of surfactant into ETT
Chest-wall movement
SpO2 by pulse oximetry
Vital signs
Pulmonary mechanics and tidal volumes
Breath sounds
ABG
CXR
Monitoring
Plugging of ETT by surfactant
Hemoglobin desaturation and increased need for supplemental O2
Bradycardia
Tachycardia
Pharyngeal deposition of surfactant
Administration of surfactant to only one lung
Administration of suboptimal dose
Increase in pulmonary hemorrhage following surfactant treatment
COMPLICATIONS
Extremely preterm infants with structural lung immaturity
Pneumonia or pulmonary hypoplasia
Perinatal asphyxia
Pulmonary edema from lung damage or fluid overload
Pulmonary edema from L-R shunting through PDA
Congenital B protein deficiency
Does Surfactant Fail ?
SRT in RDS What is RDS ? Respiratory distress in a preterm infant within first 6 hrs of life
Biochemical markers of surfactant deficiency – L/S ratio < 1.5, negative
shake test of gastric aspirates
Radiological evidence of HMD.
Systematic review of RCT confirmed that SRT in RDS reduces the mortality ,
decreases the incidence of pulmonary air leaks like pneumothorax, PIE and
lowers the risk of chronic lung diseases or death at 28 days of age.
RDS-Pathophysiology
Meconium aspiration syndrome
Pulmonary hemorrhage
Pneumonia
Congenital diaphragmatic hernia
Early bronchopulmonary dysplasia
SRT Beyond RDS
Constituents of meconium can inactivate surfactant.
Inflammatory mediators can also inhibit surfactant, as can the
protein that leaks into the alveolar spaces.
Reduced pulmonary blood flow may cause pulmonary ischemia,
with damage to the type II cells and reduced surfactant production.
Two approaches attempted: surfactant replacement and surfactant
lavage.
SRT in MAS
Infants receiving surfactant-replacement therapy required less ECMO,
without a concomitant increase in complications.
It appears that surfactant-replacement therapy for MAS consistently
improves gas exchange and short-term outcomes, especially avoidance of
air leaks and the need for ECMO.
Surfactant replacement
This takes advantage of the detergent-like property of pulmonary surfactant, in
which meconium might be solubilized and literally “washed” from the lung .
In addition to repleting the lung with functional surfactant, lavage might
theoretically remove particulate meconium.
Two 15-mL/kg aliquots of surfactant diluted in normal saline, with suctioning
performed after each.
Surfactant lavage
SRT in BPD
Pneumonia may be a/w surfactant inactivation
Facco, et al. studied kinetics of surfactant’s major component, (DSPC), in
neonatal pneumonia and concluded that DSPC t1/2 and pool size were
markedly impaired in neonatal pneumonia, and that they inversely
correlated with the degree of respiratory failure.
Improved oxygenation and a reduced need for ECMO compared with a
similar group of control infants.
Improved gas exchange compared with infants without surfactant treatment
SRT in Pneumonia
Pulmonary hypoplasia and pulmonary hypertension--hallmarks of CDH.
Morphologic and biochemical immaturity of the lung.
Exogenous surfactant as adjuvant treatment for the severe
respiratory distress a/w this disease is an attractive concept..
Lower rate of synthesis of SP-B and less SP-B in tracheal aspirates.
SRT in CDH
Molecular components involved in pulmonary haemorrhage can
biophysically inactivate endogenous lung surfactant,
Exogenous surfactant replacement - reverses this process even in the
continued presence of inhibitor molecules
SRT in Pulmonary Haemorrhage
1. Surfactant replacement, given as prophylaxis or rescue treatment, reduces the
incidence of RDS, air leaks, and mortality in preterm infants with RDS
2. Both animal-derived and newer synthetic surfactants with SP-B–like activity
decrease acute respiratory morbidity and mortality in preterm infants with RDS
3. Early rescue surfactant treatment (<2 hours of age) in infants with RDS
decreases the risk of mortality, air leak, and chronic lung disease in preterm infants
4. Early initiation of CPAP with subsequent selective surfactant administration in
extremely preterm infants results in lower rates of BPD/death when compared with
treatment with prophylactic surfactant therapy.
SUMMARY
5. Surfactant replacement has not been shown to affect the incidence of
neurodevelopmental, behavioral, medical, or educational outcomes in preterm infants.
6. Surfactant treatment improves oxygenation and reduces the need for ECMO without an
increase in morbidity in neonates with MAS.
7. Antenatal steroids and postnatal surfactant replacement independently and additively
reduce mortality, the severity of RDS, and air leaks in preterm infants.
8. Evidence demonstrating the utility of surfactant replacement therapry across the varied
spectrum of neonatal respiratory disorders other than RDS exists, but there still remains a
paucity of high-quality RCTs to recommend routine incorporation into clinical practice .
SUMMARY…
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