Surfactant Agents

Question 0

LaPlace’s Law in Alveoli

Answer 0

Pressure = (2 x surface tension) / radius

Higher surface tension equals greater compressive force inside the alveoli > collapse or difficulty opening the alveolus

Question 1

Surface tension

Answer 1

Force cause by attraction between like molecules that occurs at liquid-gas interfaces and holds liquid surfaces intact

Question 2

Prophylactic treatment

Answer 2

Preventing RDS in very-low-birth-weight infants (preterm), infants with high birth weights with evidence of lung immaturity, or infants at high risk for developing RDS.

Question 3

Endogenous surfactants

Answer 3

Lipids (85-90% surfactant by weight)

Proteins (SP-A, regulates secretion and exocytosis of surfactant and its reuptake.

Question 4

Production and regulation of surfactants

Answer 4

Synthesized in type II alveolar cells
Major stimulus appears to be inflation of lung
Recycling activity (Endogenous and exogenous)

Question 5

Exogenous surfactant

Answer 5

Three categories

Natural: human or animal source (survanta, curosurf, infasurf)
Synthetic: prepared in vitro synthesized substances (lucinactant)
Synthetic natural: none at this time

Question 6

Beractant

Answer 6

“Survanta” -modified natural surfactant (bovine)

Indications
Prophylactic for preterm infants (less than 1250g birth weight)
Should be given within 15 MINUTES or ASAP
RESCUE treatment (WITHIN 8 HOURS)

Administration
Room temp. for at least 20 minutes
4ml(100mg)/kg with 5fr catheter
4 equal doses (1/4 each) with 30 seconds bag MV between
4 positions, repeat NO SOONER than 6 hours

Special considerations
Partial airway obstruction will occur
Suctioning NOT recommended
May improve compliance rapidly, adjust vent settings quickly

Question 7

Clafactant

Answer 7

“Infasurf” -modified natural surfactant (bovine)

Indications
Prevention of RDS in infants LESS THAN 29 weeks at high risk
Administered no more than 30 minutes after birth
Rescue in premature infants less than or equal to 72 hrs old

Administration
3mL/kg birth BW delivered over 2 doses
Repeat up to total of 3 doses, 12 hours apart
Instilled through ET tube side port
4 aliquots if given with catheter, CMV for 30secs-2 mins after each

Question 8

Poractant Alfa

Answer 8

“Curosurf” -natural surfactant (porcine)

Indications
Rescue, reduces mortality and pneumothoraces
Unlabeled use
severe meconium aspirations syndrome in term infants, respiratory failure cause by group B strep infection in neonates

Administration
2.5 mL/kg, subsequent doses 1.25 mL/kg given twice 12 hrs apart
MAX 5mL/kg dose recommended
Two aliquots with 5fr catheter in ETT, no suction x1hr

Question 9

Mode of action of surfactant therapy

Answer 9

Replace and replenish deficient endogenous surfactant pool in neonatal RDS

Can be recycled into Type II cells and form a surfactant pool to regulate surface tension

Clinical outcome to improve oxygenation, FRC and compliance

Hazards/complications
Desaturation, bradycardia

Question 10

Assessment of surfactant therapy

Answer 10

Monitor pulse/cardiac rhythm before/after
Signs of airway occlusion
Color/activity level
Chest rise
Arterial O2 sats (prevent hyperoxia and hypoxia)