Hypoxic Ischemic Encephalopathy

Question 1

define HIE

Answer 1

acquired syndrome of acute brain injury characterised by:
- neonatal encephalopathy
- evidence of intrapartum hypoxia

Question 2

what are infants with HIE at risk of?

Answer 2

25-90% chance of development delay and / or cerebral palsy

Question 3

general presentation of neonatal encephalopathy?

Answer 3

> abnormal
- level of consciousness
- tone and reflexes
- breathing
- feeding
seizures

Question 4

causes of neonatal encephalopathy

Answer 4

BADSIM

• brain malformation or damage
• abnormal brain perfusion in shock, cardiac failure and trauma
• drug withdrawal
• sepsis
• intrapartum hypoxia / ischemia
• metabolic abnormality

Question 5

WHO definition of birth asphyxia

Answer 5

“ The failure to initiate and sustain spontaneous breathing
after birth”
(Low Apgar scores under 7 / need for resuscitation)

Question 6

causes of birth asphyxia

Answer 6

STICI

• sedation
• trauma
• intrapartum hypoxia or ischemia
• congenital abnormality
• infection

Question 7

define intrapartum hypoxia

Answer 7

“Impaired (placental) gas exchange leading to
progressive fetal hypoxaemia and
hypercapnoea with a significant metabolic
acidosis”

Question 8

normal base deficit at birth

Answer 8

Base excess -0.3 to -6.3 = Base deficit 0.3 to 6.3

Question 9

what could be a predictor of HIE?

Answer 9

metabolic acidosis

HIE Umbilical artery base deficit
mmol/L
4-8
(n=58)
8-12
(n=58)
12-1
(n=58)
>16
(n=59)
Mild 1 10 11 12
Mod 2 0 4 17
Severe 0 0 1 7

Question 10

what correlates to the development of cerebral palsy?

Answer 10

intrapartum hypoxia / fetal asphyxia

Question 11

what constitutes a metabolic acidosis

Answer 11

Metabolic acidosis: BE ≥ -12mmol/L or Art Cord pH < 7.0

Question 12

non-specific signs, that if occur altogether are suggestive hypoxia leading to cerebral palsy

Answer 12

• Sentinel Hypoxic event
• Sudden deterioration of fetal heart rate pattern
• Multisystem involvement
• Imaging evidence
• Apgars 0 – 6 for > 5 min

Question 13

what base deficit suggests intrapartum hypoxia?

Answer 13

> 10mmol/L

Question 14

outline the response to hypoxia

Answer 14

fetal bradycardia and diving reflex –> blood diverted to brain –> over time cardiac failure

anaerobic metabolism –> lactic acid accumulates –> metabolic acidosis

basal ganglia and subcortical white matter phasic damage

Question 15

failure of oxidative metabolism

Answer 15

A decreasing PCr/Pi ratio
* see energy metabolism

Question 16

what are the stages measured by?

Answer 16

level of conc
activity
neuromuscular control
reflexes
ANS function
seizures

Question 17

stage 1 features

Answer 17

• hyperalert
• normal activity
• normal muscle tone, mild distal flexion of posture and overactive stretch reflex
• weak suck reflex, strong moro reflex, slight tonic neck
• mydriasis and tachycardia
• absent seizures

Question 18

stage 2 features

Answer 18

• lethargic
• deceased activity
• mild hypotonia, strong distal flexion of posture, overactive stretch reflex
• weak suck, weak Moro, strong tonic neck
• missus and bradycardia
• commonly have seizures

Question 19

stage 3 features

Answer 19

• coma + no activity
• flaccid muscle tone, intermittent extension of posture, absent stretch
• absent reflexes
• unequal, fixed or dilated pupils and varied HR
• seizures not common

Question 20

Shankaran classification

Answer 20

moderate –> severe

1+ features in 3 or more categories

Question 21

see Thompson scoring chart

Answer 21

*

Question 22

Thompson score of >10 mx

Answer 22

65 PPV
100 NPV

Question 23

Thompson score of >15

Answer 23

92 PPV
82 NPV

Question 24

how do neonatal seizures present?

Answer 24

Occular
- tonic jerks
- staring, fixed blinking

Oral-buccal-lingual
- chewing
- wincing
- cry grimace

Limbs
- boxing and cycling

ANS
- Brady or tachycardic
- tachypnea / apnea

Extensor posturing

Question 25

causes of neonatal seizures

Answer 25

HHH BMEDA Hypoglycemia Hypoxia HIE Brain damage / hemorrhage / trauma Meningitis Electrolyte ab Drug withdrawal Abnormal brain perfusion

Question 26

what tests can be done to assess and monitor the CNS?

Answer 26

> EEG - most useful beside prognostic tool at age 6 hrs > cerebral ultrasound > MRI

Question 27

what might a cerebral ultrasound show?

Answer 27

oedema infarction acute bleed cystic changes

Question 28

broad management options

Answer 28

> therapeutic hypothermia > fluid mx > oxygenation

Question 29

when should neonates be offered therapeutic hypothermia?

Answer 29

term or near term infants with moderate to severe HIE

Question 30

temperature for therapeutic hypothermia

Answer 30

33-34 degrees calcium or selective head cooling 34-35

Question 31

conditions when doing therapeutic hypothermia

Answer 31

in NICU - follow protocol - IPPV, sats, BP, inotropes, Should be done within 6 hours of birth for 72 hrs --> rewarm over 4+ hrs * monitor for adverse effects

Question 32

what is the mechanism for therapeutic hypothermia?

Answer 32

metabolic depression --> energy conservation --> apoptosis inhibited --> improved protein synthesis --> glutamate not released --> decrease in IC acidosis --> reduced NO and free radical production --> reduced BBB breakdown = less inflammatory response

Question 33

current GSH cooling criteria

Answer 33

A. ALL of the following: * ≥ 35 wks and ≥ 1.8Kg * < 6 hours after birth * Absence of: severe congenital anomaly, uncontrolled bleeding, uncontrolled systemic hypotension or pulmonary hypotension not responding to treatment B. Suspected intrapartum hypoxia based on one of the following: * 1st hour pH < 7.0 or BD ≥ 10 * 5-min Apgar < 7 or assisted ventilation at 10 min C. Moderate-severe neonatal encephalopathy based on: Abnormal aEEG and signs of encephalopathy * If an aEEG is not available define encephalopathy according

Question 34

what else can go wrong in a case like this?

Answer 34

lung - surfactant deposition and delayed fluid clearance CVS - dysfunction renal - failure, hypoNa and hypoK, SIADH hepatic - hypoglycaemia, hypoalbuminemia, coagulopathy, jaundice GIT - ileus, NEC BM - thrombocytopenia

Question 35

how to manage fluids in renal failure in a neonate?

Answer 35

1. restrict fluid @40ml/kg for maintenance 2. avoid bolus unless hypovolemic 3. use K free fluids 4. monitor glucose - can give 12.5 to 15% dextrose if low

Question 36

PaO2 aim

Answer 36

8-10.6 kPa 60-80mmHg

Question 37

PaCO2 aim

Answer 37

4.4-6 kPa 33-52.5 mmHg

Question 38

mx for brain

Answer 38

treat seizures with ABC, glucose and phenobarbital

Question 39

mx for lungs

Answer 39

airway and oxygenation

Question 40

CVS mx

Answer 40

monitor pulse and perfusion

Question 41

renal mx

Answer 41

monitor output and input

Question 42

hepatic mx

Answer 42

monitor glucose

Question 43

GIT mx

Answer 43

avoid feeds unless mild - IV fluids best

Question 44

what to check if BM issue

Answer 44

signs of bleeding and subaponeurotic haemorrhage

Question 45

how to manage a neonate on ongoing ventilation or signs of moderate - severe HIE + low Apgar?

Answer 45

> admit to ICU > aEEG > cool

Question 46

how to manage a neonate with CPR or a base deficit >10, but good resus response No signs of moderate to severe HIE, but has a low Apgar

Answer 46

> admit for obs > feed cautiously > early glucose check > watch for seizures

Question 47

how to manage neonate with some resuscitation (excluding CPR) but normal by 10 mins, normal blood gas and normal blood glucose

Answer 47

stays with mom

Question 48

what % survives without disability ?

Answer 48

40%

Question 49

essential step in process

Answer 49

communication and documentation