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What are the 3 main respiratory problems of preterm babies?
- RDS
- Pneumothorax
- Apnoea and bradycardia
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What is respiratory distress syndrome due to?
Surfactant deficiency
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What does surfactant contain?
Phospholipids and proteins
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What secretes surfactant?
Type II pneumonocyte of the alveolar epithelium
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What is the function of surfactant?
To lower surface tension in alveoli and prevent collapse during expiration
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What happens to the alveolar in RDS and complication?
Collapsed alveolar and reduced GE
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RDS is rare in term babies but which term babies is it more common in?
Infants of diabetic mothers
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What can prevent RDS?
- Glucocorticoids given antenatally to the mother stimulates fetal surfactant production
- Give if preterm delivery is anticipated
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Is RDS worse in b or g?
boys
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What is the major advance in treating RDS?
Surfactant therapy
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How is surfactant therapy given?
Instilled directly into the lung via tracheal tube
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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
- Cyanosis
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What may you see on CXR of RDS
- Ground glass appearance
- Air bronchogram outlining large airways
- Heart border obliterated (severe)
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What tubes/lines may you see on CXR of RDS?
- ET tube
- Umbilical artery catheter
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What is the Rx of RDS?
- Oxygen – higher conc
- Ventilation: CPAP (nasal airway) or IPPV via ET tube
- Surfactant therapy
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What 3 things need to be monitored to adjust ventilatory requirements?
- Continuous O2 sats monitoring,
- chest wall movement,
- blood gas analysis
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what 2 outcomes does surfactant therapy reduce?
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What type of ventilation is reserved for severe RDS?
HFOV – high frequency oscillatory ventilation
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When does surfactant deficiency itself resolve spontaneously?
In 3-7 days as endogenous surfactant is produced
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What are the pulmonary complications of RDS?
- Pneumothorax
- Interstitial emphysema
- Secondary infection
- Chronic lung disease – overventilation can contribute to this
- Mechanical ventilation can cause acute lung injury
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What are the non pulmonary complications of RDS?
- Intraventricular haemorrhage
- Patent DA
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What defines apnoeic?
Cessation of respiration for at least 20 seconds
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What is apnoea associated with?
Bradycardia and desaturations
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What are the 4 main RF for apnoea?
- RDS
- Hypoxia
- Infection
- Cranial pathology, especially haemorrhage
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What are the 2 main causes of bradycardia in preterms?
- If stop breathing for long
- Or when continues to breathe against a closed glottis
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What needs to be excluded if preterm has bradycardia?
- Hypoxia
- Infection
- Anaemia
- Electrolyte disturbance
- Hypoglycaemia
- Seizures
- Heart failure
- GORD – aspiration
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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
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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
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What simple bedside test can you do to identify a pneumothorax?
Transillumination with bright fibreoptic light source applied to the chest wall
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How do you treat a tension PT?
Inserting a chest drain
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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
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what is a common cause of PDA in preterms?
RDS
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what are symptoms of PDA?
- no symptoms
- apnoea & bradycardia
- inc O2 requirement
- difficulty weaning from artificial ventilation
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what is the pulse and HS like in PDA?
- pulse: bounding from an increased pulse pressure
- systolic murmur
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why may signs of heart failure develop in PDA?
due to increased circulatory overlaid
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when do you decide to close the PDA and how?
- if symptomatic then close
- a) drugs: PG synthetase inhibitor - indomethacin, ibuprofen
- b) surgical ligation
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what are the 4 main consequences of hypothermia?
- energy consumption - leading to hypoxia & hypoglycaemia
- failure to gain weight
- inc mortality
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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
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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
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what is average fluid requirement on first days of life?
- 60-90ml/kg
- adjusted according to: clinical condition, U&E, UO, wt change
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why do preterms have a higher nutritional requirement than terms?
rapid growth rate
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when are infants mature enough to SUCK AND SWALLOW?
35-36 weeks
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before infants are able to suck and swallow how are they fed?
oro or naso gastric tube
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in very immature or sick infants how are they fed?
parenteral - PICC line - central venous catheter
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what are the 2 main risks of PICC lines?
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what is the disadv of cows milk based formula milk to mothers own breast milk?
higher rate of NEC
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why is osteopenia of prematurity now less common?
due to addition of phosphate, calcium and vitamin D
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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
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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!
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when do most infections of preterm infants happen and what is cause?
- after few days - nosocomial
- indwelling catheters
- artificial ventilation
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what are the 3 main consequences of infection in preterms?
- bronchopulmonary dysplasia - chronic lung disease
- white matter injury in brain
- later disability
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what are the 2 main preterm brain injuries (big categories)
- 1. bleeds
- 2. periventricular white matter injury
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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
- pneumothorax
- hypovolaemia
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which bleeds have a higher risk of cerebral palsy?
intraventricular
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which is the most severe type of bleed and what is its consequence?
- unilateraL haemorrhagic infarction involving parenchyma
- leads to HEMIPLEGIA
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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
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what is Rx of hydrocephalus in preterm?
- initial LP to remove CSF
- then VP shunt
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what happens to half of patients with post bleed ventricular dilatation?
- cerebral palsy
- even higher risk if also parenchymal infarction
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what causes periventricular white injury?
- ischaemia
- inflammation
- may occur in absence of bleed
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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
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what is PVL? what do you see on US?
- periventricular leukomalacia
- bilateral multiple cysts
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if PVL is posteriorly sited what is there a risk of?
spastic diplegia (symmetrical parts of body affected)
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what is the pathology of NEC?
bacterial invasion of ischaemic bowel
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what may accelerate NEC?
feeding with formula milk than only breast milk
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what are the symptoms of NEC?
- infants stops tolerating feeds
- milk is aspirated from stomach
- vomiting - bile stained
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what may you see OE NEC?
- abdomen distended
- stool - fresh blood
- infant becomes rapidly shocked
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why may you need to ventilate baby with NEC?
due to abdominal distension and pain
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what are XR features of NEC?
- distended loops of bowel
- thickening of bowel wall - intramural gas
- gas in portal tract
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what is complication of NEC and how detect - 2 ways
- perforation
- detect by XR or transillumination of abdomen
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what is Rx of NEC?
- stop oral feed
- broad spec abx - cover both aerobic and anaerobic
- parenteral nutrition
- artificial ventilation
- circulatory support
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what are the long term consequences of NEC?
- strictures
- malabsorption
- if extensive bowel resection has been necessary
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which parts of bowel does NEC usually involve?
- distal ileum
- proximal colon
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which preterms are at risk of getting the long term consequences?
very low birth weight ones
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what are the 3 main long term consequences of prematurity?
- Retinopathy of prematurity
- chronic lung disease of prematurity
- neurodevelopment problems
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where does retinopathy of prematurity affect?
developing blood vessels at the JUNCTION of the vascular and nonvascularised retina
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what happens in ROP - process? (4 things)
abnormal vascular proliferation --> progress to fibrosis, retinal detachment and blinding
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what is the cause of ROP?
- response to injurious factors
- may be hyperoxia PaO2 > 12kPa
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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
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what is Rx of ROP
- laser therapy for severe disease
- most canses resolve spontaneously
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what is the definition of bronchopulmonary dysplasia?
requiring supplemental oxygen beyond 36 weeks corrected GA
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what is the cause of BPD? 3 main things
- lung damage from pressure (barotrauma) and volume (volutrauma) trauma from artificial ventilation
- oxygen toxicity
- infection
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what does CXR of BPD show?
- widespread opacities
- patchy translucent areas
- sometimes cystic changes
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what is the cause of death of some babies with severe BPD?
- intercurrent infection
- pulmonary hypertension
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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
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what is the main worry in using steroids in BPD?
neurodevelopment problems
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what are the common reasons for readmission to hospital for BPD patient?
- recurrent wheezing
- bronchiolitis
- chest infecitons
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what can be use to reduce admission of preterm infants?
palivizumab - monoclonal Ab to RSV
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what is the nutritional advice for preterms?
iron supplements until 6 months corrected age when iron is available from solid foods
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which preterm babies are at higher risk of getting neuro problems?
- very LBW
- born very early <26 weeks
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what are the range of neurodevelopment problems?
- cerebral palsy
- cognitive delay
- visual impairment
- hearing loss
- seizures
- behavioural and educational problems
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