Respiratory Distress Syndrome Flashcards
Common causes of respiratory distress in newborns
RDS Airleak (pneumothorax) Meconium Aspiration Syndrome Neonatal Pneumonia Pulmonary Hemorrhage
Acrocyanosis
Cyanosis of the periphery (blue nails)
Cause of RDs
Deficiency of surfactant in premature babies.
Leads to poorly compliant lungs, atelectasis, increased work to breathe, and hypoxia
Likelihood of RDS at 29 week gestation? Full Term?
60%
near 0%
Risk factors for RDS?
Fetal hyperinsulinism Fetal asphyxia Multiple gestations Male>Female Caucasian>Black
Five stages of lung development
Embryonic Pseudoglandular Canacular \_\_\_- (who fucking knows) Alveolar
Embryonic period lasts from
What forms
0-6 weeks, bronchi develop
Pseudoglandular period happens from
What forms
7-16 weeks
COnducting airways, Branching pattern
Canalicular period happens from…
what forms?
17-25 weeks
Acini
Resp bronchiole, alveolar duct+Sac
Type II alveolar cells (20 weeks)
Subsaccular period happens from…
what forms?
25-35 weeks Primitive alveoli Decrese inerstitial thickness, eparate terminal air units Type I and II differentiate Lamellar bodies develop
Alveolar period happens from…
what forms?
36 w-3yo
- Invagination of terminal saccules and formation of secondary perfusion
- Collagen synthesis
- Further interstitial thinning
- Appearance of a single capillary network.
Anything born before _____ is a non-viable birth
20 weeks
You’ve got no lung to work with
What is surfactant
A lipoprotein – Saturated phosphatidylcholine
Surfactant is made where?
Smooth ER of Type II Alveolar Cells
Surfactant in stored intracellularly where?
Lamellar Bodies
Surfactant is converted to…
Tubular myelin
Who has a regulatory role in surfactant production?
Steroids and thyroid hormones
_____ stimulate the Surfactant secretion at birth
Catecholamine surge and Lung distention
What does SP-A do?
Forms an integral part of tubular myein
Inhibits secretion, but stimulates reutilization
Role in determinine surfactant pool size
What does SP-D do?
Innate host defense from viral infections
Surfactant lipid homeostasis
Protect from oxidant damage
What does SP-B do?
Surface tension reduction
Formation of Lamellar bodies + Tubular myelin
What does SP-C do?
Surface absorption of phospholipids
Agents that inhibit surfactant fxn
AMNIOTIC FLUID + MECONIUM
Albumin, Bilirubin, Cholesterol, Elastin, Blood products
Law of Laplace =
Pressure to keep it open = 2Tension / radius
Pressure required to keep an alveoli open is ____ to surface tension and _____ to alveolar radius
directly proportional
inversely proportional
Relationship between Surfactant and law of laplace
Surhactant lowers surface tension by displacing water molecules, helps alveoli not close on expiration
RDS pathogenesis
Deficient surfactant at air-fluid interfact caused by secretion problem. Causes atelectasis. Other alveoli distend and epithelial damage occurs.
Effects of no surfactant on alveoli fxn
Poor stability R to L shunting of blood Reduced effective pulmonary BF Edema Decreased Compliance
How to diagnose RDS Clinically?
Premature infants
Tachypnea, Central Cyanosis, Labored breathing
Retractions, Flaring, Grunting
Auscultation may reveal fine rales
Why do adults inspire by chest out while RDS babies go in
In adults, compliance + negative pressure will do it
Babies are less compliant lungs and ribs are still too soft.
Negative pressure causes the rib cage to collapse instead of making the lungs expand
How to diagnose RDS in Lab studies?
Hypoxia, Hypercarbia, Acidosis
How to diagnose RDS – Radiographic?
Granular densities within hours
Ground Glass appearance
How to prevent RDS?
Reduce preterm births
Predict at risk pregnancies, treat with antenatal glucocorticoid hormones
Prophylactic/Early treatment of high risk infants with exogenous surfactant in delivery room
RDS Treatment
Resuscitation by skilled team
Intratracheal administration of exogenous surfactant
Neonatal care (temp, infection control, nutrition, fluids)
Assisted ventilation
What does grunting do for baby?
Adds resistance via closed glottis
More pressure
Keeps lung/alveoli open
Potential outcomes of RDS
Recovery Barotrauma/Volutrauma Chronic lung disease Intraventricular Hemorrhage, Retinopathy of Prematurity Death
PDA closed with…
Endomethacin
