HIE Flashcards
Definition
🌺Acute or chronic impairment of gas exchange with hypoxia, hypercapnia and acidosis with consequent organ damage.
🌺 Conditions known to reduce uteroplacental blood flow or to interfere with spontaneous respiration
Causes HIE
🌻prenatal cause
-Impairment in oxygenation and perfusion due to
o Impaired placental supply due to placental insufficiency, placental abruption and uterine contractions
o Impaired umbilical supply due to cord compression/prolapsed or knots
o Impaired materno-placental supply due to maternal hypoxia or hypotension
o Impaired neonatal supply due to difficult delivery or inadequate resuscitation
🌻 Post-natal causes (uncommon):
- Severe congenital cyanotic heart diseases.
- Severe anemia due to severe hemorrhage or severe hemolysis
🌻Maternal factor:high risk factors
hypoxia, anemia, diabetes, hypertension, smoking, nephritis, heart disease, too old or too young,etc
Clinical picture of asphyxia before birth
1- Intrauterine growth restriction
2- abnormal Umbilical artery Doppler
3- abnormal Continuous heart rate recording
Clinical manifestations of asphyxia after birth
1- Meconium staining of the newborn, amniotic fluid and vernix caseosa
2- Decreased consciousness and failure of spontaneous breathing.
3- Low Apgar score with cyanosis and flaccidity
4- Pale or blue skin coloration
5-Low heart rate
6-Poor muscle tone and weak or absent reflexes
Phatho- physiology
Nelson😁
Typically, hypoxic-ischemic encephalopathy in the term and pretrem infant is characterized by
- cerebral edema, cortical necrosis, and involvement of the basal ganglia—>trem
- whereas in the preterm infant it is characterized by periventricular leukomalacia.
- Both lesions may result in cortical atrophy, mental retardation, and spastic quadriplegia or diplegia.
Apgat score
Apgar score:
A: appearance(skin color) P: pulse(heart rate) G: grimace(reactive ability) A: activity(muscular tension) R: respiration
Degree of asphyxia: according to apgar scor
Apgar score 8~10: no asphyxia Apgar score 4~8: mild/cyanosis asphyxia Apgar score 0~3: severe/pale asphyxia
The clinic features of HIE are mainly symptoms of consciousness which usually represent in tow types:
Excitation: hyperalert, irritable, hypertonia, tachycardia, tachypnea, seizure,→ mild
Depressing: coma, hypotonia, bradycardia, bradypnea, unresponsibility, etc→ moderate to sever
Severe hypoxic-ischemic encephalopathy clinical manifestations
Seizures can be delayed and severe and may be initially resistant to conventional treatments. The seizures are usually generalized, and their frequency may increase during the 24-48 hours after onset, correlating with the phase of reperfusion injury .
At that time, wakefulness may deteriorate further, and the fontanels may bulge, suggesting increasing cerebral edema.
Irregularities of heart rate and blood pressure (BP) are common during the period of reperfusion injury, as is death from cardiorespiratory failure
Complications of hie
Multiorgan systems involvement is a hallmark of HIE.
Intracranial hemorrhage) )CNS: HIE, ICH
RS: (71-86%)Patients may have severe pulmonary hypertension requiring assisted ventilation. MAS, RDS, pulmonary hemorrhage
CVS: (43-78%)May present as reduced myocardial contractility, severe hypotension, passive cardiac dilatation, and tricuspid regurgitation.
Renal: (46-72%)Renal failure presents as oliguria and, during recovery, as high-output tubular failure, leading to significant water and electrolyte imbalances.
GIS: NEC(nectotizing enterocolitis), stress gastric ulcer Others: hypoglycemia, hypocalcemia, hyponatremia
American academy of pediatrics define severe asphyxia as combination of
o Low Apgar score < 4 for at least 5 minutes o Umbilical artery pH < 7.00 (if obtained)
o Neurological insults e.g. seizures
o Multiorgan insults : Cardiac ,pulmonary ,renal or intestinal
Diagnosis
- Neuro imaging o Brain MRI
- Modality of choice for the diagnosis and follow-up of HIE
- Early detection of brain edema and brain injury (basal ganglia)
- Conventional MRI show changes by the 3 rd day
- Diffusion Weighted MRI shows changes in the 1 st 24 hours (preferred) o Cranial ultrasonography
- Less sensitive than MRI (initial scan is negative in up to 50% of cases) - EEG
3-Laboratory studies
(Electrolytes,LFT,RFT,…)
Management
1• ABCDE resuscitation
- A (air way)
- B (breathing)
- C (circulation)
- D (drug)
- E (evaluation)
2-Careful fluid management
3- Avoidance of hypoglycemia and hyperglycemia
4-Avoidance of hyperthermia - Hyperthermia has been shown to be associated with increased risk of adverse outcomes in neonates with moderate to severe hypoxic-ischemic encephalopathy [6]
5- Treatment of seizures
6- Therapeutic hypothermia (33º-33.5ºC for 72h) followed by slow and controlled rewarming for infants with moderate to severe HIE
