Respiratory Distress ✅ Flashcards
Why do extremely premature infants have problems with their lungs?
They are born at an early stage of lung development, before the development of alveoli and have deficient surfactant production for extrauterine life
What categories of factors influence fetal lung growth and maturation?
- Physical
- Hormonal
- Local
What physical factors influence fetal lung growth and maturation?
- Fetal respiration
- Fetal lung fluid
What hormonal factors influence fetal lung growth and maturation?
- Glucocorticoids
- Prolactin
- Insulin
What local factors influence fetal lung growth and maturation?
- cAMP
- Methylxanthines
What is the function of airways?
To conduct airflow
Do upper airways take part in gas exchange?
No
What maintains upper airway patency?
Stable pressure balance between collapsing forces and dilator forces of supporting musculature
Which airways take part in respiratory gas exchange?
Portions of the conducting airways of intrathoracic trachea (lower airway)
Which portions of the lower airway take part in respiratory gas exchange?
Terminal and respiratory bronchioles and alveolar ducts
What can cause narrowing of the airways?
- Inflammation
- Excessive secretions
- Reactive airways
What can narrowing of the airways lead to?
Increased resistance to airflow
What can increased resistance to airflow caused by narrowing of airways result in?
Increased work of breathing
Which thoracic and respiratory muscles are involved in respiratory function?
- Diaphragm
- Intercostal and accessory muscles
- Abdominal muscles
What are the clinical features of respiratory distress in a newborn?
- Tachypnoea (respiratory rate >60/min)
- Nasal flaring
- Grunting
- Chest recession
- Variable cyanosis
What are the common causes of respiratory distress in a neonate?
- Transient tachypnoea of the newborn
- RDS (in preterm infants)
What are the less common causes of respiratory distress in a neonate?
- Pneumonia/sepsis
- Meconium aspiration
- Pneumothorax
- Congenital heart disease/heart failure
- Persistent pulmonary hypertension of the newborn
- Hypoxic-ischaemic encephalopathy
What are the rare causes of respiratory distress in a neonate?
- Surfactant deficiency (in term infants)
- Congenital diaphragmatic hernia
- Tracheo-oesophageal fistula
- Pulmonary hypoplasia
- Pleural effusion
- Milk aspiration
- Airway obstruction
- Lung abnormalities
- Neuromuscular disordrs
- Metabolic acidosis
Give an example of a cause of airway obstruction in a neonate
Choanal atresia
Give 3 examples of lung abnormalities that can cause respiratory distress in a neonate
- Congenital pulmonary airway malformation
- Lobar emphysema
- Pulmonary sequestration
What can cause metabolic acidosis in neonates?
Inborn errors in metabolism
When is transient tachypnoea of the newborn more common?
Following C-section
What is clearance of fetal lung fluid largely dependent on?
Reabsorption of alveolar fluid via sodium channels in the lung epithelium
What influences the reabsorption of alveolar fluid in the clearance of lung fluid?
Levels of circulating catecholamines
How to levels of circulating catecholamines after C-section compare to after vaginal delivery?
They are lower after C-section
What is the result of the lower levels of circulating catecholamines after C-section delivery?
Reduced absorption of lung liquid
What allows the baby to fill the lungs with air at birth>?
The baby generates marked negative pressures
What pressure is generated by the baby at birth to fill the lungs with air?
-60cm H2O
What happens to the lung fluid with the first two or three breaths a baby takes?
Much of the fetal lung fluid is expelled
What enhances the expulsion of lung fluid?
Generation of PEEP
What generates the PEEP that helps expel lung fluid?
The baby crying against partially closed vocal cords
What happens to the lung fluid that is not expelled in the first 2-3 breaths?
It is absorbed into the pulmonary lymphatics and capillaries over the first 6-12 hours
What can delay in the absorption of lung fluid result in?
Respiratory distress
