Understanding Perinatal Asphyxia

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Questions and Answers

What is the preferred neuroimaging modality for diagnosing hypoxic-ischemic encephalopathy (HIE)?

CT Scan

Brain MRI (correct)

X-ray

Cranial ultrasonography

What phenomenon can occur in the presence of oliguria during renal complications of newborns?

Pulmonary edema

Neonatal hypertension

Hypervolemia

Acute tubular necrosis (correct)

Which of the following metabolic conditions is commonly associated with neonatal complications?

Acidosis

Hypermagnesemia

Hypocalcemia (correct)

Hypernatremia

Which clinical grading system is used to assess hypoxic-ischemic encephalopathy (HIE)?

Sarnat and Sarnat Signup and view all the answers

What is the recommended action if fetal distress is observed during delivery?

Prepare for immediate delivery Signup and view all the answers

Which of the following conditions is classified as a post-natal cause of perinatal asphyxia?

Severe congenital cyanotic heart diseases Signup and view all the answers

What indicator suggests severe fetal circulatory compromise in the context of hypoxia?

Reversed end-diastolic flow in umbilical artery Doppler Signup and view all the answers

What defines severe asphyxia according to the American Academy of Pediatrics?

Neurological insults and Apgar score < 4 for 5 minutes Signup and view all the answers

Which of the following is NOT a sign of fetal hypoxia and distress?

High cord pH levels suggesting improved oxygenation Signup and view all the answers

What clinical manifestation after delivery indicates perinatal asphyxia?

Meconium staining of amniotic fluid and low Apgar scores Signup and view all the answers

What is a key neuroprotective mechanism of moderate hypothermia in perinatal asphyxia?

Reduced vascular permeability and edema Signup and view all the answers

Which of the following is NOT a criterion for eligibility for therapeutic hypothermia?

Presence of severe lung disease Signup and view all the answers

What should be the target rectal temperature during therapeutic hypothermia?

34-35°C Signup and view all the answers

What is the recommended PaCO2 range that is considered neuroprotective?

35 - 45 mmHg Signup and view all the answers

What is the drug of choice for treating seizures in infants, even if they are asymptomatic?

Phenobarbitone Signup and view all the answers

What is the recommended approach for feeding in infants undergoing supportive care after asphyxia?

Withhold enteral feeds for the first 3 days Signup and view all the answers

What percentage of infants with hypoxic-ischemic encephalopathy (HIE) are likely to survive without permanent neurodevelopmental abnormalities?

30-40% Signup and view all the answers

What is one appropriate action regarding the withdrawal of care for severe HIE?

Active treatment should continue for at least 24 hours Signup and view all the answers

Study Notes

Definition

Perinatal asphyxia is characterized by acute or chronic gas exchange impairment resulting in hypoxia, hypercapnia, and acidosis, leading to organ damage.
The term has been updated to Hypoxic Ischemic Injury (HII).

Causes

Impaired placental supply: Placental insufficiency, abruption, and inadequate uterine contractions.
Impaired umbilical supply: Cord compression, prolapse, or knots.
Materno-placental issues: Maternal hypoxia or hypotension affecting fetal oxygen delivery.
Neonatal factors: Difficult delivery or inadequate resuscitation.
Post-natal: Severe congenital heart diseases, significant anemia, severe hemorrhage or hemolysis (uncommon).

Clinical Picture

In the Fetus

Indicators of fetal distress include:
- Intrauterine growth restriction indicating chronic hypoxia.
- Absent or reversed end-diastolic flow on umbilical artery Doppler, suggesting circulatory compromise.
- Variable or late deceleration patterns in continuous heart rate recordings, indicating distress during contractions.
- Acidotic pH in scalp or cord blood.

After Delivery

Meconium staining of amniotic fluid and newborn.
Decreased consciousness and failure to initiate spontaneous breathing.
Low Apgar score, typically indicating cyanosis and flaccidity.

Later Neurological and Multi-Organ Dysfunction

Severe asphyxia indicated by:
- Apgar score < 4 for at least 5 minutes.
- Umbilical artery pH < 7.00.
- Neurological symptoms such as seizures.
- Multi-organ dysfunction, affecting cardiac, pulmonary, renal, or gastrointestinal systems.

Hypoxic-Ischemic Encephalopathy (HIE)

Can lead to various complications including:
- Cardiac issues: Heart failure, cardiogenic shock.
- Respiratory conditions: Meconium aspiration, apnea, pulmonary hypertension.
- Renal complications: Oliguria, hematuria, acute tubular necrosis.
- Gastrointestinal issues: Necrotizing enterocolitis.
- Hematologic and metabolic abnormalities such as hypoglycemia and electrolyte imbalances.

Diagnosis

Diagnosis of HII is based on history, physical, and neurological exams rather than specific tests.
Neuroimaging methods include:
- Brain MRI: Preferred for diagnosing and monitoring HIE, showing changes within the initial days.
- Cranial ultrasonography: Less sensitive than MRI; can be misleading if negative on the first day.
- EEG: Used to detect seizures and assess the degree of encephalopathy.

Management

In the Delivery Room

Address risk factors, provide high-flow oxygen, and prepare for immediate delivery if fetal distress emerges.
Follow neonatal resuscitation guidelines and assess the severity of encephalopathy.

In the NICU

Therapeutic Hypothermia: Administer moderate hypothermia for neuroprotection, indicated for infants under 6 hours old with moderate to severe encephalopathy due to asphyxia.
Method: Maintain a rectal temperature of 34-35°C for 72 hours, followed by gradual rewarming.

Supportive Care in ICU

Ventilation: Early ventilatory support, ensuring oxygen saturation while avoiding hyperoxia. Maintain PaCO2 between 35 - 45 mmHg.
Cardiovascular care: Monitor blood pressure and maintain mean arterial pressure above 35-40 mmHg, consider inotropic support, and assess for hypovolemia.
Fluids: Maintain appropriate fluid balance; restrict initially and liberalize as urine output improves.
Neurology: Treat seizures even if asymptomatic, with phenobarbitone as the drug of choice.
Feeding: Delay enteral feeds for the first three days, reintroduce carefully while monitoring for complications.

Withdrawal of Care

Consider for severe HIE cases with poor prognostic indicators such as isoelectric or burst suppression patterns on EEG.
Continuous supportive care recommended for at least 24 hours post-delivery.

Prognosis

Mortality rates for infants with HIE range from 20-30% in the neonatal period.
Of the survivors, approximately 50% can experience long-term neurodevelopmental issues, including cerebral palsy and intellectual disabilities.

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Description

This quiz delves into the definition, causes, and implications of perinatal asphyxia, also known as hypoxic ischemic injury. Explore the factors contributing to impaired gas exchange during the perinatal period and the potential effects on organ function. Test your knowledge on this critical topic in maternal and neonatal health.