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…

Thank You