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What are the 3 main respiratory problems of preterm babies?
- Apnoea and bradycardia
What is respiratory distress syndrome due to?
What does surfactant contain?
Phospholipids and proteins
What secretes surfactant?
Type II pneumonocyte of the alveolar epithelium
What is the function of surfactant?
To lower surface tension in alveoli and prevent collapse during expiration
What happens to the alveolar in RDS and complication?
Collapsed alveolar and reduced GE
RDS is rare in term babies but which term babies is it more common in?
Infants of diabetic mothers
What can prevent RDS?
- Glucocorticoids given antenatally to the mother stimulates fetal surfactant production
- Give if preterm delivery is anticipated
Is RDS worse in b or g?
What is the major advance in treating RDS?
How is surfactant therapy given?
Instilled directly into the lung via tracheal tube
What are the signs of RDS on a baby?
- Tachypnoea > 60
- Laboured breathing with chest wall recession – sternal and subcostal indrawing, nasal flaring
- Expiratory grunting in order to create positive airway pressure during expiration and maintain FRC
What may you see on CXR of RDS
- Ground glass appearance
- Air bronchogram outlining large airways
- Heart border obliterated (severe)
What tubes/lines may you see on CXR of RDS?
- ET tube
- Umbilical artery catheter
What is the Rx of RDS?
- Oxygen – higher conc
- Ventilation: CPAP (nasal airway) or IPPV via ET tube
- Surfactant therapy
What 3 things need to be monitored to adjust ventilatory requirements?
- Continuous O2 sats monitoring,
- chest wall movement,
- blood gas analysis
what 2 outcomes does surfactant therapy reduce?
What type of ventilation is reserved for severe RDS?
HFOV – high frequency oscillatory ventilation
When does surfactant deficiency itself resolve spontaneously?
In 3-7 days as endogenous surfactant is produced
What are the pulmonary complications of RDS?
- Interstitial emphysema
- Secondary infection
- Chronic lung disease – overventilation can contribute to this
- Mechanical ventilation can cause acute lung injury
What are the non pulmonary complications of RDS?
- Intraventricular haemorrhage
- Patent DA
What defines apnoeic?
Cessation of respiration for at least 20 seconds
What is apnoea associated with?
Bradycardia and desaturations
What are the 4 main RF for apnoea?
- Cranial pathology, especially haemorrhage
What are the 2 main causes of bradycardia in preterms?
- If stop breathing for long
- Or when continues to breathe against a closed glottis
What needs to be excluded if preterm has bradycardia?
- Electrolyte disturbance
- Heart failure
- GORD – aspiration
Which respiratory stimulant can be used to treat apnoea? And name 2 other Rx
- Oral Caffeine
- Breathing will usualy start after gentle physical stimulation
- CPAP as well
In a baby with RDS, how can you tell if it develops a pneumothorax?
- Infants O2 requirement increases
- Tidal volume decreases
- Breath sounds and chest movement on affected side reduced
What simple bedside test can you do to identify a pneumothorax?
Transillumination with bright fibreoptic light source applied to the chest wall
How do you treat a tension PT?
Inserting a chest drain
What can be done to try and prevent pneumothoraces?
- Ventilate with the lowest pressures that provide adequate chest movement and satisfactory blood gases
- Ventilation is adjusted to avoid the infant breathing against the ventilator
what is a common cause of PDA in preterms?
what are symptoms of PDA?
- no symptoms
- apnoea & bradycardia
- inc O2 requirement
- difficulty weaning from artificial ventilation
what is the pulse and HS like in PDA?
- pulse: bounding from an increased pulse pressure
- systolic murmur
why may signs of heart failure develop in PDA?
due to increased circulatory overlaid
when do you decide to close the PDA and how?
- if symptomatic then close
- a) drugs: PG synthetase inhibitor - indomethacin, ibuprofen
- b) surgical ligation
what are the 4 main consequences of hypothermia?
- energy consumption - leading to hypoxia & hypoglycaemia
- failure to gain weight
- inc mortality
why are preterm infants vulnerable to hypothermia?
- larger SA to mass ratio - so greater heat loss (surface area) than heat generation (mass)
- thin skin
- heat permeable skin - so transepidermal water loss is important in first week of life
- little subcut fat for insulation
- cannot curl up
- cannot shiver
what are the 4 main ways of preventing heat loss in preterms?
- 1. convection: increase air temp in incubator, clothe - cover head, avoid draughts
- 2. radiation: cover baby, double walls for incubators
- 3. evaporation: dry and wrap at birth, humidify incubator
- 4. conduction: nurse on mattress
what is average fluid requirement on first days of life?
- adjusted according to: clinical condition, U&E, UO, wt change
why do preterms have a higher nutritional requirement than terms?
rapid growth rate
when are infants mature enough to SUCK AND SWALLOW?
before infants are able to suck and swallow how are they fed?
oro or naso gastric tube
in very immature or sick infants how are they fed?
parenteral - PICC line - central venous catheter
what are the 2 main risks of PICC lines?
what is the disadv of cows milk based formula milk to mothers own breast milk?
higher rate of NEC
why is osteopenia of prematurity now less common?
due to addition of phosphate, calcium and vitamin D
why do premature babies have low iron stores and at risk of iron deficiency?
- as most iron transferred to fetes during LAST TRIMESTER
- so need iron supplements
why are preterm infants at higher risk of infection?
- 1. because IgG is transferred in LAST TRIMESTER
- and they don't get any IgA or IgM
- 2. infection itself is a reason for preterm labour!
when do most infections of preterm infants happen and what is cause?
- after few days - nosocomial
- indwelling catheters
- artificial ventilation
what are the 3 main consequences of infection in preterms?
- bronchopulmonary dysplasia - chronic lung disease
- white matter injury in brain
- later disability
what are the 2 main preterm brain injuries (big categories)
- 1. bleeds
- 2. periventricular white matter injury
what are the 3 main types of bleeds in the brain in preterms?
- 1. intraparenchymal
- 2. germinal matrix - typically. this is above caudate nucleus
- 3. intraventricular
- what are risk factors for bleed in brain?
- perinatal asphyxia
- hypoxia - assoc with RDS
which bleeds have a higher risk of cerebral palsy?
which is the most severe type of bleed and what is its consequence?
- unilateraL haemorrhagic infarction involving parenchyma
- leads to HEMIPLEGIA
what is main consequence of intraventricular bleed, how do you recognise this?
- CSF resorption impaired so get dilatation of ventricles and maybe hydrocephalus
- signs: increase in head circumference, tense anterior fontanelles - suture lines separate
what is Rx of hydrocephalus in preterm?
- initial LP to remove CSF
- then VP shunt
what happens to half of patients with post bleed ventricular dilatation?
- cerebral palsy
- even higher risk if also parenchymal infarction
what causes periventricular white injury?
- may occur in absence of bleed
how do you detect white matter injury? and what is the outcome/course?
- USS - echodense flare
- may resolve in a week - low risk CP
- may develop cysts - shows definite loss of white matter - high risk CP
what is PVL? what do you see on US?
- periventricular leukomalacia
- bilateral multiple cysts
if PVL is posteriorly sited what is there a risk of?
spastic diplegia (symmetrical parts of body affected)
what is the pathology of NEC?
bacterial invasion of ischaemic bowel
what may accelerate NEC?
feeding with formula milk than only breast milk
what are the symptoms of NEC?
- infants stops tolerating feeds
- milk is aspirated from stomach
- vomiting - bile stained
what may you see OE NEC?
- abdomen distended
- stool - fresh blood
- infant becomes rapidly shocked
why may you need to ventilate baby with NEC?
due to abdominal distension and pain
what are XR features of NEC?
- distended loops of bowel
- thickening of bowel wall - intramural gas
- gas in portal tract
what is complication of NEC and how detect - 2 ways
- detect by XR or transillumination of abdomen
what is Rx of NEC?
- stop oral feed
- broad spec abx - cover both aerobic and anaerobic
- parenteral nutrition
- artificial ventilation
- circulatory support
what are the long term consequences of NEC?
- if extensive bowel resection has been necessary
which parts of bowel does NEC usually involve?
- distal ileum
- proximal colon
which preterms are at risk of getting the long term consequences?
very low birth weight ones
what are the 3 main long term consequences of prematurity?
- Retinopathy of prematurity
- chronic lung disease of prematurity
- neurodevelopment problems
where does retinopathy of prematurity affect?
developing blood vessels at the JUNCTION of the vascular and nonvascularised retina
what happens in ROP - process? (4 things)
abnormal vascular proliferation --> progress to fibrosis, retinal detachment and blinding
what is the cause of ROP?
- response to injurious factors
- may be hyperoxia PaO2 > 12kPa
what is the 'screening' of ROP?
- all infants with very LBW >1500g or less than 32 weeks GA
- have eyes screened 6-8 weeks after birth
what is Rx of ROP
- laser therapy for severe disease
- most canses resolve spontaneously
what is the definition of bronchopulmonary dysplasia?
requiring supplemental oxygen beyond 36 weeks corrected GA
what is the cause of BPD? 3 main things
- lung damage from pressure (barotrauma) and volume (volutrauma) trauma from artificial ventilation
- oxygen toxicity
what does CXR of BPD show?
- widespread opacities
- patchy translucent areas
- sometimes cystic changes
what is the cause of death of some babies with severe BPD?
- intercurrent infection
- pulmonary hypertension
what is the treatment of BPD?
- initially - may still need assisted ventilation or CPAP and supplemented O2
- dexamethasone for weaning from ventilatory support but increases risk of neurodevpt impairment so only use in severe cases
- strict attention to nutrition
what is the main worry in using steroids in BPD?
what are the common reasons for readmission to hospital for BPD patient?
- recurrent wheezing
- chest infecitons
what can be use to reduce admission of preterm infants?
palivizumab - monoclonal Ab to RSV
what is the nutritional advice for preterms?
iron supplements until 6 months corrected age when iron is available from solid foods
which preterm babies are at higher risk of getting neuro problems?
- very LBW
- born very early <26 weeks
what are the range of neurodevelopment problems?
- cerebral palsy
- cognitive delay
- visual impairment
- hearing loss
- behavioural and educational problems