[88] Prematurity Flashcards
What common problems are associated with prematurity?
- Respiratory distress syndrome
- Necrotising enterocolitis
- Infection-
- Hypoglycaemia
- Temperature control
- Retinopathy of prematurity
- Intraventricular haemorrhage
What is the problem in RDS?
Deficiency of surfactant
What is the role of surfactant?
Lowers surface tension
What is surfactant made up of?
A mixture of phospholipids and proteins
What excretes surfactant?
Type 2 pneumocytes of the alveolar epithelium
What does surfactant deficiency lead to?
Widespread alveolar collapse and inadequate gas exchange
What happens to the incidence of RDS with increasing prematurity?
Increases
Who is RDS common in?
Infants born before 28 weeks
In what gender does RDS tend to be more severe in?
Boys
Can you get surfactant deficiency at term?
Rare, but can occur in diabetic mothers
How can RDS be avoided?
Glucocorticoids given to mother antenatally if preterm delviery is anticipated
How does maternal administration of glucocorticoids help in RDS?
Stimulates foetus to produce surfactant
What has been a major advancement in the treatment of RDS?
Development of surfactant therapy
What is surfactant therapy made from?
Extracts of calf or pig lung
How is surfactant therapy administered?
Instilled directly into lung via tracheal tube
How effective is surfactant therapy in RDS?
Shown to reduce mortality from RDS by 40% without increasing morbidity rate
When do symptoms of RDS begin?
At birth or within 4 hours of birth
What are the clinical signs of RDS?
- Tachypnoea >60breaths/min
- Laboured breathing with chest wall recession and nasal flaring
- Expiratory grunting
- Cyanosis if severe
What causes expiratory grunting in RDS?
It is to try and create positive airway pressure during expiration and maintain functional residual capacity
What does the CXR shown in RDS?
Diffuse granular or ‘ground glass’ appearance of lungs
Air bronchogram
Heart border becomes indistinct or completely obscured with severe disease
How is RDS treated?
Raised ambient oxygen, may need to be supplemented with CPAP or artificial ventilation via tracheal tube
What do the ventilation requirements need to be adjusted on the basis of in RDS?
According to infants oxygenation, chest wall movements, and blood gas analysis
What can be used to wean infants from added oxygen therapy in RDS?
High-flow humidified oxygen therapy via nasal cannulae
What is necrotising enterocolitis?
A serious illness associated with bacterial invasion of ischaemic bowel wall
Who does necrotising enterocolitis affect?
Mainly preterm infants in first few weeks of life
How does the feed of an infant affect their risk of necrotising enterocolitis?
Preterm infants fed on cow’s milk formula are more likely to develop this condition than if they are fed only on breast milk
How does necrotising enterocolitis present?
- Stops tolerating feeds
- Milk aspirated from stomach
- May be bile-stained vomiting
- Abdomen becomes distended
- Stool sometimes contains fresh blood
How might the presentation of necrotising enterocolitis progress?
Infant may rapidly become shocked and require artificial ventilation due to abdominal distention and pain
What are the characteristic x-ray features of necrotising enterocolitis?
- Distended loops of bowel
- Thickening of bowel wall with intramural gas
What might complicate necrotising enterocolitis?
Bowel perforation
How can bowel perforation in necrotising enterocolitis be detected?
- X-ray
- Transillumination of abdomen
What is the treatment for necrotising enterocolitis?
- Stop oral feeding
- Broad spectrum antibiotics
- Parenteral nutrition
- Artificial ventilation and circulatory support if required
What do the antibiotics given in necrotising enterocolitis need to cover?
Aerobic and anaerobic organisms
What treatment is required for bowel perforation caused by necrotising enterocolitis?
Surgery
What is the mortality of necrotising enterocolitis?
20%
What are the long-term complications of necrotising enterocolitis?
- Development of strictures
- Malabsorption if extensive bowel resection was necessary
Why do preterm infants have an increased risk of infection?
- IgG is mostly transferred across placenta in last trimester, and no IgA and IgM transferred - Infection in or around cervix is often reason for preterm labour, and may cause infection shortly after birth
When do most infections in pre-term infants occur?
After several days
What are infections in pre-term infants often associated with?
- Indwelling catheters
- Artificial ventilation
How long after birth is hypoglycaemia particularly likely?
24 hours of life
What can cause hypoglycaemia in the first 24 hours of life?
- Preterm
- IUGR
- Mothers with diabetes
- Large for gestational age
- Hypothermic
- Polycythaemic
- Ill for any reason
Why can premature and IUGR babies get hypoglycaemia?
Poor glycogen stores
What are the symptoms of neonatal hypoglycaemia?
- Irritability
- Apnoea
- Lethargy
- Drowsiness
- Seizures
Why can many babies tolerate low glucose?
Due to use of lactate and ketones
What glucose level is desirable in neonates?
> 2.6mmol/L
Why is glucose level >2.6mmol/L desirable?
For good neurodevelopment