NNU Teaching - HIE and neurodevelopment Flashcards
(19 cards)
What overall causes HIE?
- Perinatal asphysxia - hypoxia, hypercarbia, metabolic acidosis
- = diminished brain perfusion
- Brain injury from ischaemic changes in the brain
Causes of HIE
- Problem in gas exchange across placenta - abruption, ruptured uterus
- Disrupted umbilical flow - prolapse, shoulder dystocia
- Inadeqate maternal perfusion - hypotension, hypoxia
- Compromised foetus - anaemia, IUGR, congenital infections, heart and lung problems
- Failure in transition
Mechanism of brain injury
- Primary energy failure = brain injury (loss ATP) - babies can cope with short periods eg 10 mins)
- Latent phase - secondary energyy failure and brain damage (can get reperfusion injury from oxidative stress and neuroinflammation)
What is re-perfusion injury? - what happens?
- Higher NTs
- Higher free radicals
- Higher intracellular calcium
- Inflammatory mediators
- = ongoing damage to brain cells
Parts of brain susceptible to HIE
- Internal capsule
- Basal ganglia
Clinical presentation of HIE
- Hypotonia
- Loss primative reflexes
- Lethargic (loss of spontaneous movement) or very irritable
- Abnormal posturing
- Seizures
- Feeding difficulties - suckling reflex affected
Classifying severity of HIE
- Sarnat and Sarnat staging
- Mild, moderate and severe
- Based on level of conc, reflexes, tone, seizures, duration
What was TOBY trial?
Evaluated use of therapeutic cooling in term babies who suffered with moderate-severe HIE
Criteria for therapeutic cooling
- Infants must be at least 36 weeks
- Seizures or moderate/severe encephalopathy (CFM machine can be used to assess this)
How does cooling work?
- Interventions need to be within 6 hours - secondary phase of brain damage starts here - reperfusion injury
- Cooling prevents secondary phase of injury
- Target temperature 33-34 degrees (measured rectally)
- Have 72hrs of it (cooling jacket)
Complications of hypoxic injury
- Brain damage - HIE
- Heart - poorly perfused eg cyanosis, low BP (may need inotropes)
- Liver - LFTs deranged, clotting abnormal
- Kidneys - creatinine rising, poor urine output
- Bowel - not routinely feeding at the start,
- Sepsis - due to bone marrow injury
Managment of HIE
- A - E management
- Ventilate if needed, make sure CO2 is normal
- C - may need inotropes, boluses if very deplete (but not too many), fluid restrict to make sure no cerebral oedema. Maintain BP
- D - therapeutic cooling, maintain normal glucose, treat seizures (uses up lots of O2)
- E - monitor for cooling complications - necrosis of where lay
Imaging for HIE
- MRI - gold standard - do 7-10 days - diffusion weighted imaging injury apparent within 7 days (if very poorly, can do sooner if think outcome is poor and intervention may need to stop) (black internal capsule)
- USS - cranial, can do through fontanelle, can see cerebral oedema and bright basal ganglia. Can do doppler studies to see blood flow.
When is cerebral palsy an increased risk of HIE?
- Seizures
- Severe encephalopathy
- Abnormalities of basal ganglia or lack of myelin on MRI
Why are preterm babies more at risk of brain injury - what can happen?
- Haemorrhage - typically germinal matrix (fragile BV) eg Intraventricular haemorrhage which can extend to parenchymal haemorrhage (grade 3-4 ventricles enlarged), highest risk within 72hrs, avoid BP rises
- Periventricular white matter brain injury - ischaemia or inflammation, risks of parenchymal breakdown (cysts) = periventricular leukomalacia = spastic diplegia
Long term problems post prematurity
- Survival
- Cognitive impairement
- Cerebral palsy
- Educational attainment
- Attention/behavioural - ADHD, ASD, anxiety, SEN
- Hearing/visual impairments
- Other systems problems - resp, cardiac etc
Guidance for f/u of babies born preterm
- NICE guidance
- F/U until 2 yrs of age
Criteria for 2yr f/u neurodevelopment
- Preterm infants < 30 weeks gestation
- Preterm infants 30+1
36+6 weeks gestation and has or had 1 or more of the
following risk factors:
* A brain lesion on neuroimaging likely to be associated with developmental problems or disorders (for example, grade 3 or 4 intraventricular haemorrhage or cystic periventricular leukomalacia)
* Grade 2 or 3 hypoxic ischaemic encephalopathy in the neonatal period
* neonatal bacterial meningitis
* herpes simplex encephalitis in the neonatal period.
* Infants with HIE (cooled or not cooled)
* Infants with chronic lung disease (CLD)
* Any infant with significant abnormality on brain imaging
* Infants with significant or multiple congenital anomalies
* Syndromic diagnoses
* Infants at risk of neonatal abstinence syndrome (NAS)
* Other neonatal problem (discussed at discharge planning)
