Mod 13 Surfactent Flashcards
When is Surfactant produced?
Produced at 24-34 (26) gestation
What produces Surfactant?
Type 2 Alveolar Cells
What is the main component of Surfactant?
Main lipid = dipallmitolyphosphatiylcholine (DPPC)
- composed of phospholipids, lipids, and proteins
- DPPC is the agent that decreases surface tension
Where is Surfactant stored?
Lamellar bodies in the cytoplasm of type 2 cells
- 1000 mg/kg in term infants
- 4-5 mg in preterm infants
What is the half life of surfactant?
5-10 hrs
- 1/2 life = time it takes for the amount of a drugs active substance in your body to reduce by half
Can surfactant be recycled?
Yes, up 90% of DPPC recycled is reabsorbed into type 2 cells
What is exogenous surfactant?
outside the pts own body
- external surfactant is used to replace deficient pulmonary surfactant of premises w/rds
- Used to replace surfactant deficiency from outside the body
What is the recommended dose of Surfactant?
5 ml/kg given as 2 divided doses by direct tracheal instillation
- can be repeated q12hrs an again q24hrs if needed
Aside from lipids, what is the protein composition in surfactant?
20% protein portion = SP-A, SP-B, SP-C, SP-D
split this into others later**
What is the composition and purpose of each protein portion in surfactant?
- i.e SP-A etc. etc.
SP-A – high molecular weigh, water soluble glycoprotein – seems to regulate secretion and exocytosis of surfactant from the type II cell, and reuptake
SP-B and SP-C – low molecular weight, hydrophobic proteins – improve adsorbtion and spreading of the phospholipid throughout the air-liquid interface in the alveolus
SP-D – similar to SP-A – large, water soluble protein, molecular configuration is different. Unsure as to purpose, could be incorrectly labelled as surfactant specific protein.
What is Colfosceril Palmitate (Exosurf)/ synthetic Surfactant a risk of causing?
High risk of pulmonary hemorrhage
What is the goal of Surfactant replacement?
Lower surface tension and decrease the amount of pressure and inspiratory effort to re expand the alveoli during inspiration
What affect does Exogenous surfactant have on surface tension, compliance, and WOB?
- what is the aim?
- Decreases surface tension
- Increase compliance
- Decrease WOB
Why can exogenous surfactant be recycled by the body?
Exogenous surfactant is taken back into type 2 cells and becomes the surfactant pool to go through the same recycling process that endogenous surfactant goes through
How many doses of exogenous surfactant is needed?
- why?
1 or 2 doses bc it can be recycled into the body
Clinical indications for surfactant use? (7)
- RDS prevention,
- Rescue/retroactive treatment,
- Prophylactic
What are common Surfactants used in canada?
Bovine Lipid Extract Surfactant (BLES) and Beractant (Survanta)
Why does BLES allow rapid distribution?
Bles has lower viscosity and high protein concentration.
Composition of BLES?
Mixed with DPPC and agents to reproduce natural surfactant; contains:
- 27 mg phospholipids/ml
- SP-B and SP-C
- Kept frozen, needs rewarding to room temp
Indications for BLES? (4)
- Rescue Tx of RDS (Confirmed by CxR requiring mech vent w/increasing O2 reps, than its ASAP)
- Prophylaxis for infants < 27 weeks of age
- Mod-Severe MAS
- Oxygen deterioration
Contraindication for BLES?
active pulmonary hemorrhage
Recommended dose for BLES?
5 ml/kg by direct tracheal instillation
- can be repeated 3 time within the first 5 days of life if needed
Dose for Beractant (Survanta)
4ml/kg when using birth weight
How is Beractant (survanta) different from BLES?
Made with bovine lung extract mixed with DPPC, Palmitic acid, and triplmatin.
- its a modified version of bles basically
- also contains surfactant specific proteins SP-B and SP-C
