Module 9: Jasmine Flashcards
What are the 5 stages of lung development?
- Embryonic: Weeks 3 to 7
- Pseudoglandular: Weeks 5 to 17
- Canalicular: Weeks 16 to 25
- Saccular: Weeks 24 to 40
- Alveolar: 36 Weeks to Childhood
**there is some overlap between the stages
What is the Embryonic stage of lung development?
Embryonic: Weeks 3 to 7
- Initial budding and branching of the lung buds from the primitive foregut.
- At the end of the embryonic stage, the larynx, trachea, lung primordia, lobe of the lungs, and bronchopulmonary segments have formed.
What is the Pseudoglandular stage of lung development?
Pseudoglandular: Weeks 5 to 17
- This stage is primarily responsible for the generation of the bronchial tree.
- At the end of this stage, the respiratory tree has developed as far as the terminal bronchioles, with the formation of the arterial system, cartilage, and smooth muscle.
- Respiration is not possible during this phase because the respiratory bronchioles have not yet developed, and therefore infants born during this period are unable to survive.
- The diaphragm also develops during this stage.
What is the Canalicular stage of lung development?
Canalicular: Weeks 16 to 25
- This stage marks the division between the conducting and respiratory units in the respiratory tree.
- At this time, the gas-exchanging portion of the lung is formed and vascularized.
- At the end of this stage, some respiration is possible so some infants can survive if provided with intensive care.
What is the Saccular stage of lung development?
Saccular: Weeks 24 to 40
- During this stage, the gas-exchange surface area of the lungs significantly expands.
- The important blood-air barrier is established.
- Specialized cells of the respiratory epithelium appear at this time, including type I alveolar cells across which gas exchange occurs, and type II alveolar cells that secrete pulmonary surfactant.
- This surfactant is important in reducing the surface tension at the air-alveolar surface, allowing expansion of the terminal saccules.
What is the alveolar stage of lung development?
Alveolar: 36 Weeks to Childhood
- During this stage, the terminal saccules, alveolar ducts, and alveoli increase in number.
- At term, the lungs are functional, although not just simply a smaller version of the adult lung.
- The number of airway generations and their branching pattern is complete at birth but the most peripheral airways are short and contain transitory saccules that will eventually form into alveoli.
- In fact, over 85% of alveolarization takes place after birth
What happens to lungs without surfactant?
without surfactant:
- lungs have very high surface tension,
- predisposing them to alveolar collapse and
- respiratory distress syndrome (RDS).
What kind of respiratory support will infant born before 33 weeks need?
- either a ventilator or a CPAP machine,
- due to lung immaturity
What medication is given antenatal if premature birth is anticipated to accelerate fetal lung maturation?
- routine practice that when premature birth is anticipated, a course (two doses) of antenatal corticosteroids are given to the mother accelerate fetal lung maturation.
What is Continuous Positive Airway Pressure (CPAP)?
Continuous positive airway pressure (CPAP)
- is a non-invasive form of respiratory support that applies continuous pressure on an infant’s airway, so that at the end of expiration, some air remains in the lungs and the alveoli do not collapse.
- CPAP helps reduce surface tension, prevent atelectasis, and maintain adequate lung volume, particularly functional residual capacity (FRC) and tidal volume.
- This reduces the infant’s reliance on tachypnea as a way to eliminate carbon dioxide.
** CPAP does not work for all infants.
To be successful on CPAP as a mode of respiratory support:
- have a respiratory drive and
- adequate respiratory muscles to support and
- sustain good respiratory effort and tidal volumes.
What is mechanical ventilation?
- Mechanical ventilation is an invasive form of respiratory support that assists or replaces spontaneous breathing.
- Because of the associated pulmonary pathophysiology, infants with BPD can and often do experience hypoxia, hypercapnia, and apnea, and therefore may require mechanical ventilation.
- Unfortunately, mechanical ventilation, while it does effectively treat hypoxia, hypercapnia, and apnea, also increases pulmonary damage: the very damage that is contributing to hypoxia, hypercapnia, and apnea.
- Mechanical ventilation is a good example of a therapy that has many benefits but that also increases an infant’s vulnerability.
Infant was born at 26 weeks of gestation. What is her stage of lung development?
- born during the saccular phase of lung development (24-40)
- which is about the midpoint of fetal development, when the lung volume increases markedly due to saccule development, and subdivision of the saccules into alveoli commences.
- During this time, surfactant production is just beginning.
- Jasmine’s lungs are not fully developed and also lack surfactant.
- This will put her at risk for respiratory complications that may require respiratory support.
If infant was born at 23 weeks gestation, how would this affect her lung development/risk?
- she would be in the canalicular stage of lung development (16-25)
- Her lungs would be underdeveloped and lacking in surfactant.
- infant would most definitely experience respiratory distress and need respiratory support.
What is the long term consequence of RDS?
- bronchopulmonary dysplasia (BPD) or chronic lung disease (CLD).
What is bronchopulmonary dysplasia (BPD) associated with (2)?
- increased mortality and morbidity and
- significant long-term cardiac, respiratory, sensory and neuro-developmental sequelae
What is the “Old BPD” characterized as?
- is characterized mainly by lung damage and fibrosis caused by oxygen toxicity and mechanical ventilation.
- Over the years, advances in gentler modes of ventilation, surfactant administration, antenatal corticosteroid administration and developmentally supportive care have changed the presentation of BPD
What is “New BPD” characterized as?
- is characterized by interruption of normal lung development resulting from interference with alveolarization and pulmonary vascular development in extremely preterm infants.
Has Old BPD been replaced by new BPD?
- Old BPD has not been replaced by new BPD; rather,
- they are two different types of lung injury that present with different gestational age infants and different physiological and clinical pictures.
How does infection/inflammation affect development of BPD?
- Lung inflammation, infection, and injury predispose the lung to increased susceptibility to volutrauma and oxidant-induced lung injury.
- The cycle of inflammation can produce significant pulmonary injury during periods of rapid growth and development.
How does oxygen toxicity affect the development of BPD?
- Oxygen produces free radicals (molecules that are toxic to cells/tissue).
- Antioxidants protect against free radicals but if there is increased free radical production (high 02 concentrations) or decreased antioxidant levels (common in preterm infants), the lungs become susceptible to damage and oxidative stress.
How does antenatal corticosteroids affect the development of BPD?
- Accelerates the development of type 1 (gas exchange) and type II (surfactant) alveolar cells.
How does mechanical ventilation affect development of BPD?
- BPD is a result of barotrauma (alveolar rupture/damage due to pressure) and volutrauma (over-distention/stretch) of alveoli in infants who are receiving positive pressure ventilation.
- Using the lowest pressures possible decreases the risk for BPD, although some infants require higher pressures for survival.
How does fluids and nutrition affect the development of BPD?
- Infants who are born small for gestational age (SGA) or intrauterine growth restricted (IUGR) are already at increased risk for BPD/CLD at birth due to undernourishment in utero and compromised lung development.
- After birth, adequate nutrition is also very important as inadequate nutrition results in catabolism, which increases the effect of oxygen and barotrauma on the developing lungs.
- Fluid balance is also key as fluid overload also increases the risk for BPD/CLD.
What risk factors, both prenatal and postnatal, have placed Jasmine at an increased risk for developing BPD?
- preterm (born at 26 weeks gestation)
- mother had a prenatal infection
- potential for infection with cerclage insertion
- required weeks of mechanical ventilation
- oxygen supplementation
- history of a PDA
What care, both prenatal and postnatal, can help to minimize or prevent BPD?
- Ultimately preventing preterm birth would prevent BPD
prenatal care prevention:
- antenatal corticosteroids
- antibiotics to treat infections
- maternal health and well-being
postnatal care prevention:
- minimize invasive ventilation
- minimize hyperoxia
- administer surfactant
- ensure early detection and treatment of PDA
- administer caffeine
- provide developmentally supportive care
What is sudden infant death syndrome?
- the sudden death of an infant less than one year of age