Hypoxic- Ischemic Encephalopathy : An Overview

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Hypoxic- Ischemic Encephalopathy An Overview

• Saba Merchant

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Case Baby P

• Full term infant born to 37 yo G4 P1 by emerg. CS
• Initial VBAC, late decels, mat fx-ampicillin,
  fetal scalp gases 7.23 and 7.31
• decels and brady - CS - uterine rupture - baby
  in abd
• At birth no HR, RR, tone, poor color, no response
  to stimuli
• dried, suctioned, bag mask within 30sec,
  HRlt60,some chest movt, again bag and mask HRlt60
• Intubated at 1min 15sec, A/E good but HRlt60,
  reintubated and chest compression epi
• Revisualise tube and reintubated - epi
• Apgars 0 1 1 7
• 1st gas 6.99/33/146/8/-23 at 37 min

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Case contd

• O/E no dysmorphisms, AGA, vented, neurologically
  compromised, hyperexcitable - clonus, hypotonia,
  poor suck/swallow, gag absent, DTR exagg.,
  planter clonus
• PB started, weaned from ventilator, extubated 4
  days later to R/A, feeds started 7 days later
• CT scan head, EEG, HUS, neurology consult
• 14 days later transferred to level 2
• Secretions, suction , longterm G tube
• Rpt EEG and VEP pending
• At present parents signed DNR

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HIE

• Definition
• It is the term used to designate the clinical and
  neuropathological findings of an encephalopathy
  that occurs in a full term infant who has
  experienced a significant episode of intrapartum
  asphyxia.

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Incidence of Asphyxia

• 2 in full term and 60 in LBW
• 20-50 die in newborn period
• Of survivors 25 have permanent handicap

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Definitions

• Hypoxia/anoxia denotes a partial or complete
  lack of oxygen, respectively, in one or more
  tissues of the body, including the blood stream.
• Asphyxia is the state in which pulmonary or
  placental gas exchange is affected leading to
  progressive hypoxemia, which is severe enough to
  be associated with acidosis.
• Ischemia is a reduction in or cessation of
  blood flow that arises from either systemic
  hypotension, cardiac arrest, or occlusive
  vascular disease.

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Pathology

• Severity and distribution is dependent on several
  factors
• certain vulnerable areas - cerebral cortex ,
  hippocampus , basal ganglia, thalamus, brain
  stem, subcortical and periventricular white
  matter
• In full term infants gray matter structures
  affected and in premature infants white matter
• Four basic and clinically important lesions
  Neuronal necrosis, status marmoratus,
  para-sagittal cerebral injury, periventricular
  leucomalacia

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Status of infant at birth

• Depressed on initial assessment
• Generalized hypotonia
• Apgars 3 or less _at_ 1min and 6 or less _at_ 5min
• Major resuscitation required
• Large base deficit by blood gas
• Poor feeding to deep coma (ecephalopathic)

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Prognosis based on apgars

• Score at 1, 5 minutes does not give prognosis
  indicator
• The longer the score remains lower, the greater
  its significance
• 0-3 _at_ 1min has mortality of 5-10
• may be increased to 53 if at 20min apgars
  score 0-3
• 0-3 _at_ 5min , CP risk app. 1
• may be increased to 9if for 15min
• dramatic rise to 57 CP risk if for 20min

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Newborn neurological assessment

• Staging system of Sarnat and Sarnat
• Means of recording severity of insult to brain,
  to initiate med management and to predict
  ultimate prognosis
• Infants occasionally sustain insult to brain
  arising from complication of systemic disease
• Seizures in 50-70

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Summary of staging (table no to memorizejust to
know)

• Mild Hyperalertness, uninhibited reflexes,
  sympathetic overactivity , duration lt 24 hrs
• Moderate Lethargy-stupor, hypotonia, suppressed
  primitive reflexes, seizures
• Severe Coma, flaccid tone, suppressed brainstem
  function, seizures, increased ICP

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Prognosis based on Sarnat and Sarnat

• Stage 1 invariably recover without neurological
  deficit
• Stage 2 later develop normally if clinical and
  EEG abnormalities are fully reversed in 5 days
  of birth
• Stage 3 encephalopathy is associated with a high
  mortality(50) and universal neurological
  morbidity among the survivors.

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Systemic Complications of Perinatal Asphyxia

• Acute Tubular Necrosis
• Hematurea, High BUN and creatinine
• Hepatic necrosis or ischemic dammage
• Elevated liver enzyme
• Cardiomyopathy
• Hypotension, weak heart muscle in Echo

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Management

• Prevention, prevention, prevention
• Insure physiological oxygen and acid-base balance
• Maintain environmental temp and humidity
• Correct caloric, fluid and electrolyte
  disturbances
• Maintain blood volume and hemostasis
• Treat infection
• Neuro-resus measures to reduce cerebral oedema
  ineffective
• Sz treated with PB, dilantin or lorazepam
• Newer modalities- excitatory amino antagonists,
  oxygen free radical inhibitors/scavengers, ca
  channel blockers, nitric oxide synthetase
  inhibitors
• Hypothermia

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Case presentation

• Delivery of term baby after emergent C/S because
  of severe abdominal pain and at delivery fetus
  had prolonged and severe bradycardia. Placenta
  was found to be fully separated at delivery. Baby
  came out severely hypotonic, unresponsive, heart
  rate of 40/min.blue in color with no respiratory
  effort. 2 hours later on mechnical vetilator baby
  start to have seizure. After 20 days baby is not
  alert can not feed orally and hypertonia start to
  appeare

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Question and Answers

• Student should explain baby clinical finding at
  delivery based on history.
• Should estimate apgars score and discuss what it
  means in term of resuscitation
• Classify baby HIE to Sarnat stages including
  other component to examinE
• Predict prognosis and outcome

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