Perinatal asphyxia

Perinatal asphyxia

Cover image: Ellie Remus lies on a specially designed cooling pad in the neonatal intensive care unit at Women & Children’s Hospital in April. The photo was taken by her father. | Davis, H., & News, T. (2013). Cooling newborns to save their lives. The Buffalo News. Retrieved 21 May 2018, from http://buffalonews.com/2013/11/30/cooling-newborns-to-save-their-lives/

Introduction

Insult to the fetus/newborn due to a lack of oxygen (hypoxia) and/or a lack of perfusion (ischemia) to various organs.

  • Associated with tissue lactic acidosis & hypercarbia

Epidemiology

1024px-birth_asphyxia_and_birth_trauma_world_map_-_daly_-_who2002-svg
Disability-adjusted life year (DALY) for birth asphyxia and birth trauma per 100,000 inhabitants in 2002 | Lokal_Profil, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=8401011

Aetiology

Risk factors:

  • Elderly/young mothers
  • Prolonged rupture of membranes
  • Meconium-stained fluid
  • Multiple births
  • Lack of antenatal care
  • LBW infants
  • Malpresentation
  • Augmentation of labour with oxytocin
  • Antepartum haemorrhage
  • Severe eclampsia and pre-eclampsia
  • Antepartum/intrapartum anemia

Cause:

  • Inadequate oxygenation of maternal blood
    • Due to hypoventilation during anaesthesia, heart diseases, pneumonia, respiratory failure
  • Low maternal blood pressure
    • Due to hypotension e.g. compression of vena cava and aorta, excess anaesthesia
  • Inadequate relaxation of uterus
    • Due to excess oxytocin
  • Premature separation of placenta
  • Placental insufficiency
  • Knotting of umbilical cord around the neck of infant

Pathophysiology

Neuropathology:

  • Premature newborns:
    • Selective subcortical neuronal necrosis
    • Periventricular leukomalacia(PVL)
      • Due to hypoxic-ischemic insult leading to coagulative necrosis and infarction of periventricular white matter (watershed area between various arteries)
    • Focal and multifocal ischemic necrosis
    • Periventricular haemorrhage/infarction
  • Term newborns:
    • Selective cortical neuronal necrosis
    • Status marmoratus of basal ganglia and thalamus
      • Variant of selective neuronal necrosis involving basal ganglia and thalamus, having longterm sequelae
    • Parasagittal cerebral injury
    • Focal and multifocal ischemic cerebral necrosis

Other lesions (due to small infarcts secondary to blocking of end arteries):

  • Porencephaly
  • Hydrancephaly
  • Multicysticencephalomalacia

Multiorgan dysfunction:

  • CNSHypoxic ischemic encephalopathy, cerebral oedema, long-term neurological sequelae
  • PulmonaryPulmonary hypertension, meconium aspiration, surfactant disruption
  • RenalAcute renal failure
  • MetabolicMetabolic acidosis, hypoglycemia, hypocalcemia, hyponatremia
  • GINecrotizing enterocolitis, hepatic dysfunction
  • HaematologicalThrombocytopenia, disseminated intravascular coagulation

Clinical features

Selective neuronal necrosis:

  • Diminished consciousness
  • Seizures
  • Abnormalities of feeding, breathing, etc

Parasagittal cerebral injury:

  • Spastic quadriparesis

Status marmoratus:

  • Long-term sequelae:
    • Choreoathetosis
    • Spastic quadriparesis
    • Retardation

Periventricular leukomalacia (PVL):

  • Long-term sequelae:
    • Spastic diplegia
    • Quadriplegia (lower limbs >upper limbs)
    • Visual impairment

Diagnosis

Clinical criteria

American Academy of Pediatrics Committee on Fetus and Newborn:

  • Prolonged metabolic or mixed acidemia (pH <7.0) on an umbilical arterial blood sample
  • Persistence of Apgar score of 0-3 for >5 min
    • National Neonatology Forum of India (NNF) and WHO:
      • Apgar of 0-3 and 4-7, at 1 min
  • Neurological manifestations:
    • e.g. seizures, coma, hypotonia or hypoxic-ischemic encephalopathy (HIE) in the immediate neonatal period
  • Evidence of multiorgan dysfunction in the immediate neonatal period

Levene classification for HIE (hypoxic-ischemic encephalopathy) staging:

For babies of gestational age > 36 weeks

Feature Mild Moderate Severe
Consciousness Irritability Lethargy Comatose
Tone Hypotonia Marked hypotonia Severe hypotonia
Seizures No Yes Prolonged
Sucking/respiration Poor suck Unable to suck Unable to sustain spontaneous respiration

Management

Medical management

Admit to NICU

  • Indications:
    • Need for positive pressure ventilation for ≥ 30 seconds, chest compression or adrenaline
    • Apgar <7 at 5 minutes

Temperature:

  • Maintain normal temperature of the baby
  • Avoid hyperthermia
  • Resourceful setting:
    • Moderate induced hypothermia (core temperature of 33°-34° C)

Ventilation:

  • Oxygen saturation (90-95%)
  • CO2 concentration (40-50 mm Hg)

Perfusion:

  • Systemic mean arterial pressure:
    • 45-50 mm Hg (term)
    • 35-40 (1-2 kg weight)
    • 30-35 mm Hg (<1 kg weight)

Metabolic profile:

  • Look for hypocalcemia and electrolyte disturbances
  • Glucose: 75-100 mg/ dl
  • Seizures:
    • Antiepileptic drugs (AEDs)
      • Phenobarbitone
      • Phenytoin

Prognosis

Poor prognosis if:

  • Lack of spontaneous respiratory effort within 20-30 minutes of birth is associated with almost uniform mortality
  • HIE stage 3
  • Abnormal neurological findings persisting beyond the first 7-10 days of life
  • Oliguria (<1 ml/kg/ day) during the first 36 hr

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