Preterm Babies Flashcards
What are some of the respiratory complications of prematurity?
RDS
Apnoea of Prematurity
Bronchopulmonary dysplasia
What is the primary and secondary pathology in RDS?
Primary: surfactant deficiency and structural immaturity
Secondary: alveolar damage, formation of exudate from leaky capillaries, inflammation, repair
How common is RDS?
75% of infants before 29wks
How does RDS present?
Shortly after birth with:
Tachypnoea Grunting Intercostal recessions Nasal flaring Cyanosis
Worsens over mins-hrs
What is the clinical course of RDS?
- As disease progresses, baby may develop ventilatory failure (rising CO2) and aponea
- Clinical course 2-3days whether tx or not
What is the tx of RDS?
Maternal steroid
Surfactant
Ventilation (CPAP)
What does RDS look like on CXR?
“ground glass” appearance
Air bronchograms
What are the complications of RDS?
Pneumothorax
Lung collapse
Mediastinal shift
Chronic lung disease (O2 requirement at 28days of life)
What is the definition of aponea of prematurity?
Cessation of breathing by a premature infant that lasts >20s for is accompanied by hypoxia or bradycardia
What are the underlying causes of apnea of immaturity?
Obstructive (baby’s neck flexed)
Central (lack of resp effort)
Mixed
What is the pathophysiology of apnea of immaturity?
- Ventilatory drive is dependent on response to increasing CO2 levels and acid in the blood.
- Hypoxia is a secondary stimulus.
- Responses to these stimuli are impaired in premature infants due to immaturity of specialised regions in brain that sense these changes
What is the tx of apnea of prematurity?
Caffeine
CPAP
How does pneumothorax in the premature infant arise and what is the tx?
- In RDS air from over distended alveoli track into interstitial, results in pulmonary interstitial emphysema
- In up to 10% infants ventilated for RDS: pneumothorax
- Tx: chest drain for tension pneumothorax
What is bronchopulmonary dysplasia?
“chronic lung disease”
Babies still require oxygen >36wks
How does bronchopulmonary dysplasia arise?
Lung damage comes from pressure and volume trauma from artificial ventilation, oxygen toxicity and infection
What does a CXR show in bronchopulmonary dysplasia?
- Widespread areas of opacification, sometimes with cystic changes
- Fibrosis and lung collapse
- Overdistension of lungs
What does hypothermia lead to in a premature baby?
Increased energy consumption
Hypoxia and hypoglycaemia
Failure to gain weight
Increased mortality
Why are preterm infants at an increased risk of hypothermia?
- Large S.A to vol ratio, therefore greater heat loss.
- Skin is thin and heat permeable so transepidermal water loss in first week of life.
- Little subcut fat for insulation
- Nursed naked and cannot conserve heat by shivering
How can heat loss be prevented in newborns
- CONVECTION
- clothing, incubator - RADIATION
- cover baby, double walls for incubators - EVAPORATION
- dry and wrap at birth, place in plastic bag - CONDUCTION
- nurse on heated matress
What happens to the ductus arteriosus during development and at birth?
Development: DA kept open by vasodilator prostaglandin E2 made by placenta & DA itself.
At birth:
- O2 levels increase, lungs become source of oxygenated blood, E2 levels fall and DA closes.
- Lungs produce bradykinin to help close off DA (day 1)
What are the CV complications of prematurity?
PDA
Systemic hypotension
What is the pathophysiology of PDA?
- Classed as acyanotic, however when atrial pressure increases, can result in a R–>L shunt and cyanosis in lower extremities.
- Connection between pulmonary trunk and descending aorta.
What is the association with PDA?
- More common in premature infants
- Associated with PDA in first trimester
What are the clinical signs/symptoms in PDA?
Left subclavian thrill Continuous 'machinery' murmur Large vol, bounding, collapsing pulse Wide pulse pressure Heaving apex beat
What does PDA lead to?
Symptoms of congestive heart failure
Exacerbates RDS
What is the fluid balance in premature infants?
First day of life: about 60-90ml/kg needed.
Subsequent fluid vol increased by 20-30ml/kg/day to 150-180ml/kg/day
How much does premature babies’ weight increase by?
At 28wks: double their weight in 6wks, treble in 12wks
How does term babies’ weight increase?
Double in 4.5months, treble in one year
What are some neurology complications of prematurity?
IVH
HIE
How does IVH arise?
Typically bleeds occurs in the germinal matrix above the caudate nucleus which contains a fragile network of blood vessels
What is the presentation of IVH?
- Most occur within 72hrs of life
- More common following severe perinatal asphyxia and RDS.
What is a significant risk factor for IVH?
Pneumothorax
How is IVH graded?
Cranial US grades this according to whether it is periventricular or spreads into the ventricles/parenchyma
What is the most severe IVH?
Unilateral haemorrhagic infarction involving the brain parenchyma, usually resulting in hemiplegia
What is a major risk with IVH?
- A large IVH can impair drainage and reabsorption of CSF, build up.
- This can resolve spontaneously or progress to hydrocephalus
What is the tx of hydrocephalus in the neonate?
Initially LP then shunt
What are the greatest risks associated with IVH?
Hydrocephalus and cerebral palsy
What is the clinical presentation of IVH?
- Inverse relationship between gestational age and birth
- 2 major risk factors: prematurity and RDS
- Up to 90% occur in first 72hrs
- 25-50% clinically silent
What are some of the preventative measures in IVH?
Antenatal steroids
Prompt and appropriate resuscitation
Avoid haemodynamic instability
Avoid: hypoxia, hypercarbia, swings in BP
What is the grading for IVH?
Grade 1+2:
- Neurodevelopment delay in up to 20%
- Mortality 10%
Grade 3+4:
- Neurodevelopment delay in up to 80%
- Mortality 50%
How does HIE arise?
- Due to compromise of placental or pulmonary gas exchange resulting in cardiopulmonary depression.
- Placenta, baby (IUGR, anaemia), failure of adaptation
What is the sequelae of HIE?
- Hypoxia, hypercarbia and metabolic acidosis follow.
- Compromised cardiac output diminishes tissue perfusion casing HIE to brain and other organs
When do symptoms of HIE arise?
Immediately or up to 48hrs after asphyxia
What constitutes mild, moderate and severe HIE?
Mild: irritable and responds to stimulation.
Moderate: abnormalities of tone and movement, can’t feed.
Severe: no spontaneous movements or response to pain
What is the primary and secondary cause of neuronal damage in HIE?
Primary: immediate from neuronal death
Secondary: delayed from reperfusion injury
What is the tx of HIE?
Resp support, ionotropes, electrolytes
What is the prognosis for HIE: mild/moderate/severe?
Mild: complete recovery
Moderate: if feeding well and normal neuro= good prognosis. If abnormalities, full recovery unlikely.
Severe: mortality 40%, CP 80%
What are the complications of HIE?
CP, LD, epilepsy, hearing and visual impairment
What is NEC?
- One of the leading causes of death among premature infants.
- During first few weeks of life, a portion of the bowel dies.
NEC is more likely to develop if on cow’s milk compared to breast-feeding T/F?
True
What are some of the initial symptoms of NEC?
- Feeding intolerance
- Abdominal pain
- Distension of abdomen
- Vomiting
- Bloody stools
How can NEC progress?
- Can progress quickly to abdominal distension, perforation and peritonitis.
- May require ventilation
How does vomiting arise in NEC?
Baby stops tolerating feeds, milk is aspirated from the stomach and there may be vomiting which is bile stained.
What might an AXR show in NEC?
- Dilated bowel loops (asymmetrical in distribution)
- Bowel wall oedema
- Pneumonalis intestinalis (intramural gas)
- Pneumoperitoneum
- Air inside and outside bowel wall (Rigler’s sign)
- Air outlining falciform ligament (football sign)
What is the tx for NEC?
- Stop oral feeding–>TPN
- Broad spectrum Abx
- Artificial and circulatory support may be needed
- Surgery for bowel perforation
What are some of the complications of NEC?
- Significant morbidity and mortality
- Development of strictures
- Malabsorption if extensive bowel resection necessary
How does Retinopathy of prematurity arise?
- In utero, blood vessels grow from central retina outwards and is complete a few weeks before birth.
- Incomplete in premature babies.
- Blood vessels may grow and branch abnormally and bleed.
- Band membranes formed pull up retina, causing detachment and blindness <6months.
What is the sequelae of ROP?
Vascular proliferation–> retinal detachment, fibrosis and blindness
What are the risk factors for ROP?
- Prematurity
- High exposure to O2
- Low birth weight
- Infections
- Cardiac defects
What is the tx for ROP?
- At risk babies (<1.5kg or <32wks) require ophthalmology screening every week.
- Laser tx for severe disease
Who is at risk of severe bilateral visual impairment in ROP?
In 1% of v.low birthweight babies <28wks