Hypoxic Ischemic Encephalopathy

Hypoxic Ischemic Encephalopathy

Hypoxic Ischemic Encephalopathy

Hypoxic Ischemic Encephalopathy (HIE) is a type of newborn brain damage caused by oxygen deprivation and limited blood flow.

Hypoxic Ischemic Encephalopathy is when the brain does not get enough oxygen, permanent brain damage can result. Hypoxic Ischemic Encephalopathy is a type of birth injury; this is a broad term used to refer to any harm that a baby experiences at or near the time of birth. Other terms used for HIE include birth asphyxiaperinatal asphyxia, and neonatal encephalopathy.

Hypoxic Ischemic Encephalopathy falls under the Broad term “Encephalopathy

Encephalopathy

Encephalopathy is a general term used to describe damage or disease affecting brain function. The causes are varied and can be related to infection, liver conditions, drug toxins, and more.

Some of the major types include the following:

  • Chronic Traumatic Encephalopathy: This condition occurs due to direct injury to the brain, leading to nerve damage. This type is commonly found in athletes.
  • Hepatic Encephalopathy: Often caused by liver cirrhosis, when the liver is not able to filter and function properly, toxins accumulate in the blood and brain.
  • Glycine Encephalopathy: This type of encephalopathy is genetic with symptoms appearing after birth.
  • Toxic Metabolic Encephalopathy: This type of encephalopathy results from toxins, infections, or organ failure. When chemical composition in the body becomes imbalanced, it can impact the brain’s normal function. 
  • Hypoxic-Ischemic Encephalopathy: When the brain does not get enough oxygen, permanent brain damage can result.
  • Hypertensive Encephalopathy: Prolonged hypertension that is not treated can cause the brain to swell resulting in neurological damage.
  • Uremic Encephalopathy: If the kidneys are not functioning properly, they cannot filter harmful substances. The buildup of uremic toxins can cause confusion and other symptoms.

Etiology of Hypoxic Ischemic Encephalopathy

Pathologically, any factors which interfere with the circulation between maternal and fetal blood exchange in form of  maternal factors, delivery factors and fetal factors.

Maternal factor: 
  • hypoxia,
  • anemia,
  • diabetes,
  • hypertension,
  • smoking,
  • nephritis,
  • heart disease,
  • too old or too young,etc 
Delivery condition: 
  • Abruption of placenta,
  • placenta previa,
  • prolapsed cord,
  • premature rupture of membranes,etc 
Fetal factor
  • Multiple birth,
  • congenital or malformed fetus,etc 

High Risk Factors

  • Mismanagement of a high-risk pregnancy: Women with conditions such as preeclampsia and gestational diabetes require more extensive monitoring and treatment.
  • Umbilical cord complications: The umbilical cord is like a lifeline between mother and baby, supplying oxygen and nutrients and removing fetal waste. Anything that compresses the cord or reduces its function puts the baby at risk of HIE.
  • Placental or uterine complications: The placenta and uterus also play very important roles in providing oxygenated blood to the baby. Examples of placental and uterine issues that may cause HIE include:
    • Placental abruption: when the placenta separates from the uterus before the baby is born
    • Placenta previa: when the placenta attaches too close to the cervix; this can cause dangerous bleeding and oxygen deprivation during delivery
    • Placental insufficiency: when the placenta is unable to deliver enough blood to the baby
    • Uterine rupture: when the uterus tears, partially or completely
  • Infections: Infections in the mother can spread to the baby during labor and delivery, especially if the medical team do not take adequate precautions (such as doing indicated infection screening and prescribing antibiotics when needed).
  • Improper fetal heart monitoring: If a baby shows signs of fetal distress on the fetal heart monitor, doctors and nurses can often intervene so that their oxygen supply is restored. If necessary, this may involve an emergency C-section. However, if monitoring is sporadic or does not occur, important signs of danger may be missed.
  • Failure to prevent a premature birth: Premature babies are at higher risk for HIE and other birth injuries because their lungs are so underdeveloped. Therefore, it is very important that doctors do what they can to prevent premature birth, such as performing a cervical cerclage (a stitch placed in the cervix to stop it from opening too early) or providing progesterone treatment.
  • Allowing prolonged labor to continue: Labor is stressful for babies because uterine contractions compress the placenta and umbilical cord that supply their oxygen. If something is preventing labor from progressing, and physicians do not offer intervention (such as an emergency C-section), this is negligence. Prolonged labor is more likely to occur when a baby is larger than normal, or the mother’s pelvis is smaller than normal.
  • Medication problems: Sometimes physicians prescribe medications such as Pitocin and Cytotec in order to induce or enhance labor. Unfortunately, these medications can also cause uterine contractions to become so strong and frequent that the baby is dangerously deprived of oxygen.
  • Mismanagement of a neonatal condition: Hypoxic-ischemic injury can be caused by complications during the neonatal period, i.e. a baby’s first month of life. Problems such as respiratory distress, jaundice, and neonatal hypoglycemia can all contribute to an HIE diagnosis, especially if mismanaged.

Clinical Features of Hypoxic Ischemic Encephalopathy

  • Breathing problems
  • Feeding problems
  • Missing reflexes (for example, the baby does not respond to loud noises)
  • Seizures
  • Low Apgar scores
  • Low or high muscle tone
  • Altered level of consciousness (e.g. not alert)

Classification of Hypoxic Ischemic Encephalopathy 

Clinical Classification

  • Mild(stage I): hyperalert, irritable, normal muscular tone & reflex, no seizure, normal EEG 
  • Moderate(stage II): lethargy, hypotonia, weak sucking & Moro response, often seizure, EEG+
  • Severe(stage III): coma, absent muscular tone & reflex, persistent seizure, EEG++

Levene Classification

FeatureMildModerateSevere
CONSCIOUSNESSIrritableLethargyComatose
TONEHypotoniaMarkedSevere
SEIZURENoYesProlonged
SUCKING/ RESPIRATIONPoor SuckUnable to SuckUnable to maintain Spontaneous respiration

Sarnat Staging Classification 

(Commonly used)

Sarnat staging is used alongside electroencephalogram findings to provide information about the prognosis for the infant.

 Grade I MildGrade II ModerateGrade III Severe
AlertnessHyperalertLethargyComa
Muscle toneNormal or increasedHypotonicFlaccid
SeizuresNoneFrequentUncommon
PupilsDilated, reactiveSmall, reactiveVariable, fixed
RespirationRegularPeriodicApnoea
Duration< 24 Hours2 – 14 DaysWeeks

EEG brain scans may detect signs of autism in 2-year-olds - CBS Newselectroencephalogram

 

Management of Hypoxic Ischemic Encephalopathy

This is a pediatrics emergency.

  • HIE is managed using a treatment called therapeutic hypothermia, where the baby’s brain or body is cooled down below normal temperatures to slow damage.
  • This allows the baby’s brain to recover and reduces the level of disability they may have as they grow. According to current guidelines, the treatment must be given within six hours of birth, not exceeding  24 hours.
  • The treatment of encephalopathy varies, depending on the underlying cause of the condition.

Generalized treatment

  • Ventilation: CPAP(continuous positive airway pressure) , CMV(continuous mandatory ventilation), HFOV (High-frequency oscillatory ventilation )
  • Perfusion/Circulation: Dopamine/Dobutamine
  •  Energy: normal glucose level maintained (50-110mg/dl): Hypo and hyperglycemia avoided
  • Fluid: 60-80ml/kg/d restriction if SIADH(Syndrome of inappropriate antidiuretic hormone secretion)
  • Electrolytes- Sodium and Calcium should be monitored.
  • Avoid Polycythemia: If Hct>65-70, partial exchange transfusion is done to bring Het level to 55.
  • Control of seizures: HIE seizures are difficult to control ;
  • Phenobarbital loading dose 15-20mg/kg, iv maintenance dose 3-5mg/kg, iv
  •  Phenytoin  loading dose 15-20mg/kg, iv maintenance dose 5mg/kg, iv Midazolam: 0.1-0.3mg/kg, iv Leveracetam, Topiramate
  • EEG 
Special Investigations 
  • Continous AEEG- Amplified EEG used for cerebral function monitoring. Detects voltage pattern- burst, low voltage, isoelectric Detects electrical seizure activity
  •  CT scan: only indicated in emergency 
Prognosis 

Depend on the severity of brain damage & medical treatment, usually

  • Mild or moderate cases could be cured completely, but severe cases represent poor prognosis with high mortality or cerebral complications such as mental retardation & cerebral palsy.
  • Overall mortality 20%
  • Overall incidence of sequele 30%
  • Mild: 100% good prognosis
  • Moderate: 80% normal
  • Severe : 50% death, 50% sequele 

Presence of seizure increases chance of Cerebral palsy by 50-70 times

Prevention 
  • Better Obstetric care
  • Skilled resuscitation teams and neonatal facilities.

Nursing Diagnosis

  1. Acute Confusion related to Hypoxia ,Disturbance in cerebral metabolism ,Accumulation of toxins in the brain, Structural changes in the brain as evidenced by Cognitive dysfunction , Altered psychomotor performance , Tremors, Fluctuation in the level of consciousness, Agitation, Misperception, Neurobehavioral manifestations, Difficulty initiating purposeful behavior.
  2.  Impaired Memory related to Neurological disturbances related to encephalopathy, Inadequate intellectual stimulation, Changes in brain structure and processes, Irreversible brain damage, Depressive symptoms as evidenced by Reports experiences of forgetfulness, Consistently forgets to schedule or keep appointments , Difficulty recalling events, Difficulty recalling familiar names, objects, and words, Inability to learn or retain new skills or information, Inability to perform a previously learned skill.
  3. Disturbed Thought Processes related to Insufficient oxygen supply to the brain secondary to encephalopathy, Head trauma related to encephalopathy, Infections as evidenced by Incorrect perception of stimuli, Difficulty performing activities of daily living , Difficulty communicating verbally, Impaired interpretation of events, Impaired judgment, Impaired decision making, Inadequate emotional responses, Disorientation
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