Obstetrics and Gynecology · MU Sofia

40. Asphyxia of the newborn - causes, diagnosis, management. Primary resuscitation of the newborn

Covers neonatal asphyxia, explaining it as impaired gas exchange around birth, and sets out causes in a table grouped by timing: before labour, during labour and after birth. Next it describes signs, cord blood gas thresholds and hypoxic-ischaemic encephalopathy with Sarnat stages. The note then walks through primary resuscitation step by step, from preparation and airway to breathing, compressions and drugs, and closes with post-resuscitation care such as therapeutic hypothermia.

Inside: 4 sections · 1 table · 16 flashcards · 3 min

Topic 40 of 61 in the MU Sofia syllabus for Obstetrics and Gynecology (Medicine, Year 5). The free AceMed note covers it in 4 sections, about 330 words (3 min of reading), with 16 flashcards.

In this note

  1. Introduction
  2. Causes
  3. Diagnosis and assessment
  4. Primary resuscitation of the newborn

Introduction

Neonatal asphyxia is impaired gas exchange around birth leading to hypoxia, hypercapnia and acidosis. About 10% of newborns need some help to start breathing, and less than 1% need extensive resuscitation.

Diagnosis and assessment

  • Signs: no breathing or gasping, bradycardia, poor tone, pale or blue colour; a low Apgar score.
  • Cord blood gases: metabolic acidosis (arterial pH < 7.0 and base deficit ≥ 12 mmol/L) supports intrapartum asphyxia.
  • Hypoxic–ischaemic encephalopathy (HIE), Sarnat stages 1–3: irritability, poor feeding, seizures, coma. Multi-organ effects: kidney, heart, liver, gut, coagulation.

Primary resuscitation of the newborn

  1. Before birth: warm room, resuscitaire, equipment checked, team ready.
  2. At birth: start the clock; dry and wrap, keep warm (plastic bag for preterm < 32 weeks); delay cord clamping if the baby is well.
  3. Assess tone, breathing and heart rate (stethoscope, then ECG or pulse oximetry).
  4. Airway: head in the neutral position; jaw thrust if needed; suction only if the airway is blocked (routine suction of meconium is not advised).
  5. Breathing: if gasping, not breathing or heart rate < 100/min, give 5 inflation breaths (30 cm H₂O for 2–3 s each), then ventilation breaths at 30/min, starting with air in term babies.
  6. Reassess the heart rate after 30 seconds of effective ventilation; check the chest moves (most failures are airway problems).
  7. Circulation: if heart rate stays < 60/min despite effective ventilation, start chest compressions at 3:1 (3 compressions : 1 breath, about 120 events a minute) with 100% oxygen.
  8. Drugs through an umbilical venous catheter: adrenaline 10–30 µg/kg IV, volume (10 ml/kg saline or blood) for blood loss, glucose for hypoglycaemia.

After resuscitation

  • Check glucose, temperature, gases; observe in the neonatal unit.
  • For moderate or severe HIE in babies ≥ 36 weeks: therapeutic hypothermia (33–34 °C for 72 hours) started within 6 hours of birth reduces death and disability.
  • Stopping resuscitation is considered when there is no detectable heart rate after 10–20 minutes of full resuscitation.

Ventilation is the key to newborn resuscitation: a heart rate that rises after inflation breaths means the lungs are being aerated.

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