Pulmonary Surfactant Flashcards
When was Surfactant discovered?
1920’s
When was the Significance of Surfactant discovered?
End of the 1950’s (surfactant deficiency RDS)
What is surfactant?
A surface-active lipoprotein complex formed by Type II Alveolar cells
Surfactant lines the _______ and the smallest __________.
Alveoli
Bronchioles
Surfactant is produced during the _________ ____ stage of lung development (17-26 wks)
Terminal sac stage
Term infants have a storage pool of approximately _____ mg/kg of surfactant.
Pretermers have ___-___ at birth.
100 mg/kg
4-5 mg/kg
Alveolar surfactant can be both broken down by __________ and/or reabsorbed into the __________ structures of the Type II cells
Marcrophages
Lamellar
Up to ___% surfactant is recycled from the Alveolar space in the NB
90%
What 3 factors negatively effect Surfactant quality & production
- Hyperinsulinism
- Acidosis
- MAS (chemical pneumonitis is the probable culprit)
What are the 5 functions of surfactant?
- Increases Pulmonary compliance
- Reduces surface tension
- Facilitates recruitment of collapsed airways
- Protection of the pulmonary epithelium
- Prevents Atelectasis at the end of expiration
What is compliance?
The ability of the lungs & thorax to expand
What is water surface tension?
What is lung surface tension?
70 Dynes/cm
25 Dynes/cm
*but at end of expiration, compressed surfactant phospholipid molecules decrease surface tension very low (near 0)
Surfactant allows lungs to inflate more _______ and _______ WOB
easily
Decreases
Studies of exogenous surfactant administration–>______increase oxygenation and rapid decrease in degree of _________ _____ support required.
Also increased _____ & followed by slower & variable _______ in lung compliance. Also ______in V/Q mismatch.
rapid
mechanical vent
FRC
Increase
Decrease
As the _______ increase in size, the ________ becomes distributed.
This also helps all _______ expand at the same rate.
Alveoli
surfactant
Alveoli
Keeping airways _____ is very important.
dry
By reducing surface tension with Surfactant, the fluid from ________ is not drawn into the alveolar spaces.
What happens without Surfactant?
This keeps the airways ____
capillaries
Surface tension forces draw fluid from the capillaries to the Alveolar spaces
Dry
What is the composition of Surfactant?
~40% DPPC (phospholipid-strongest molecule)
~40% other phospholipids (PC)
~5% surfactant-associated proteins (SP-A, B, C, & D)
Cholesterol (neutral lipids)
Traces of other substances
What is the strongest surfactant molecule in pulmonary Surfactant mixture?
Dipalmitoylphosphatidylcholine
DPPC
Name 3 Dz’s r/t Surfactant Deficiency
- RDS
- Congenital Surfactant Deficiency
- Pulmonary Alveolar Proteinosis
Name 3 other Dz’s you may see Surfactant used
- MAS-Mec inhibits surfactant fxn–> Alveolar collapse. Chemical pneumonitis & acidosis can also have negative effects.
- Pulmonary Hemorrhage
- Pneumonia
(not routine use in the above 2–efficacy is not certain)
Name the 3 types of Surfactants
- Synthetic Surfactant
- Animal-Derived Surfactant
- Human Amniotic Fluid-Derived Surfactant
Which type of Surfactants are used the most?
Animal-Derived Surfactant
What is the name of the Synthetic surfactant?
Exosurf–can be w/or without protein components
What are the names of the 3 Animal-derived Surfactants?
What are they produced from?
Curosurf—minced pig lung
Infrasurf—calf lung lavage fluid
Survanta—minced cow lung w/additional DPPC, palmitic acid and tripalmitin
Has human-derived surfactant undergone clinical trials?
Is it in use in clinical practice?
Yes
No
What is the administration technique for Surfactant?
ETT
What method of administration is promising in the future?
LMA
- *needs to be studied in large, randomized trial
- *& LMA’s are only avail >1500 gms
T/F: Surfactant could be used for Re-treatment w/signs of worsening or persistent RDS.
True
A Low/High threashold for peak dosing should be used for babies w/RDS who have perinatal depression or infection.
Low threashold for peak dosing
Surfactant is ________ metabolized. There is some _______ _________ of surfactant d/t action of soluble proteins and other factors in the small airways & alveoli.
What may be required?
Quickly
Functional Inactivation
Subsequent doses
What does Meta-Analysis of Surfactant studies show?
Decreased risk of pneumothoraces w/multiple-dose Surfactant therapy (practice & pt dependent)
What should be monitored when giving Surfactant?
- ETT patency and position
- O2 sats, EKG, B/P (watch for post-dose hyperoxia, hypocarbia, & over-ventilation)
- Blocked airway
Use Surfactant in what type of setting?
Highly supervised clinical settings w/immediate availability of clinicians w/experience w/intubation, ventilation management, & general care of preterm infants.
When should dosing of Surfactant be slowed or halted?
If dusky, aggitated, HR slows, SpO2’s decrease 15% or more, or surfactant backs up into ETT.
Name the adverse effects/precautions for Surfactant
- Reflux of surfactant up the ETT
- Oxygen desaturation (r/t transient hypoxemia & bradycardia)
- Pulmonary hemorrhage (2-4%, smallest pts w/untx’d PDA d/t rapid fall PVR–>increased pulmonary blood flow)
- Post dose hyperoxia, hpocarbia and/or overventilation–>possible pnuemo
Are you likely to see adverse effects/precautions in practices used to using Surfactant?
No
There is increased risk of death and short-term morbidity r/t what adverse effect of Surfactant?
Pulmonary Hemorrhage
Studies show increased liklihood of hemorrhage r/t which surfactant product?
Animal vs. Synthetic
What might you need to give after Surfactant is given?
Increased FiO2 or vent settings (i.e. MAP)
Has the rate of IVH fallen since the use of Surfactant?
No consistent effect on IVH has been observed.
Animal-derived surfactant has specific proteins that aid in __________ _______ and resist _________ ____________
surfactant absorption
Surfactant inactivation
Animal-derived surfactants have more rapid ______ of action
onset
Animal-derived surfactants should be favored in clinical situations because of greater ________ than synthetic surfactants
benefits
