CH 2 Neonatal Pulmonary Physiology and Pathophysiology Flashcards
A near term infant (34 - 36 weeks gestation) is at risk of presenting with what 4 pathologies?
- Hyaline membrane disease HMD
- Pulmonary Hypertension
- Sepsis
- Pneumonia
What are the most common newborn disorders treated with ECMO ?
- MAS
- CDH
- Sepsis
- Pneumonia
- Idiopathic Pulmonary Hypertension
Surfactant is composed of several phospholipids which lower surface tension of the alveolar walls.
Why is surfactant important during the initial opening of the alveolar walls?
What secretes surfactant ?
- Prevention of subsequent atelectasis
- Secreted by Type II alveolar cells in the lungs
How is HMD characterized ?
Hyaline membrane disease is characterized by:
- (lack of surfactant)
- Massive alveolar atelectasis > Hypoxia
What are 2 indicators of pulmonary maturity?
By G week 35:
- ) Lecithin : Sphingomyelin = 2 : 1
- ) Presence of Phosphatidyl glycerol (PG)
What is the major constituent of surfactant ?
Lecithin comprises 50 - 75% of all phospholipids
Control of fetal pulmonary circulation are modulated by several agents, what are the 2 most important VASODILATORS?
- Nitric Oxide
- Prostacyclin
Control of fetal pulmonary circulation are modulated by several agents, what are the 2 most important VASOCONSTRICTORS?
What are 2 secondary vasoconstrictors?
- Endothelium-1
- Platelet activating factor
Secondary Vasoconstrictors:
- Leukotrienes
- Thromboxane
A near term infant with HMD should be treated with what therapy before considering ECMO ?
- Surfactant
- HFV
- Inhaled Nitric Oxide
In term infants, what can turn off surfactant production ?
- Acidosis
- Hypoxia
Lung Compliance (CL) formula =
Volume / Pressure
Lung compliance is decreased in patients with HMD and therefore, an increase in pressure is needed for expansion of the lungs.
Lung Compliance Normal values range from ?
What values do we often see in HMD pts ?
1 - 4 cc/cmH2O/Kg
1/4 - 1/5 of the above + increase work of breathing.
What treatment should i use for a patient with HMD ?
Why ?
Continuous Positive Pressure Ventilation (CPAP)
- Opens the alveoli
- Decreases atelectasis
- Decreases the work of breathing
- Increases lung compliance
- Increases oxygenation
What are 7 predisposition factors for HMD ?
- Prematurity
- Perinatal asphyxia
- Maternal diabetes A,B,C
- Family HX of HMD
- 2nd twin
- C Section w/o labor
- Male
Risks for HMD can be decreased by doing the following:
- Glucocorticoid admin to the mother 24 - 48 before birth.
- Maternal toxemia
- Premature / Prolonged rupture of the membranes.
- Lecithin : Sphingomyelin > 2 : 1
- Presence of Phosphatidyl glycerol
How would a clinician determine if an infant is surfactant deficient and would benefit from artificial surfactant ?
Clinicians must use clinical findings.
- X-Rays
- Required intubation (ETT)
- FiO2 > 40 mmHg
Infants with HMD requiring FiO2 > .50 would benifit from recruiting collapsed alveoli. How can we achieve this ?
- Nasal CPAP
- High Flow Nasal Cannula
- Longer inspiratory times > .5 sec
- High Frequency Oscillatory Ventilation (HFOV)
Where should we keep blood gases for patients with HMD ?
pH 7.28
PaCO2 45-50 mmHg
PaO2 50 - 65
What plays a role in the development of bronchopulmonary dysplagia (BPD) ?
- Oxygen &
- Ventilator therapy
Therefore these patients should be aggressively weaned from these therapies.
How is bronchopulmonary dysplagia (BPD) characterized?
Thickening and eventual necrosis of:
- Alveolar walls
- Basement membranes
- Bronchiolar Epithelial lining layers
Atelectasis & fibrosis are present
Diffusion of Oxygen is impaired