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Section 1 — Delivery Room & Stabilization Pending expert review v1.0 · July 2026

Chapter 1.7 — The Transitioning Circulation & the Compromised Newborn

Board-review synthesis · pending expert review

Educational guideline — verify locally. Pairs with the resuscitation, HIE, and PPHN guidelines.

1. Clinical Overview

Clinical Overview

Birth demands an extraordinary physiologic transition in minutes: the lungs must become the gas-exchange organ, the placenta is removed, and three fetal shunts must close. When the transition fails or reverses, the newborn is blue, grey, or slow to pink up. This guideline covers the transition, its reversibility, perinatal asphyxia as a multi-organ disease, and the reasoning behind resuscitation.

2. Key Clinical Points

Key Clinical Points
  • Three shunts, three triggers: foramen ovale closes when LA pressure exceeds RA pressure; ductus arteriosus constricts as O2 rises and prostaglandins fall; ductus venosus closes when umbilical inflow is removed at cord clamping.
  • Shunts close functionally before anatomically; hypoxia, acidosis, or cold stress can raise PVR and reopen right-to-left shunting (the transition is reversible — the basis of PPHN).
  • Pre-/post-ductal pulse oximetry is the key bedside test; a gap >~3% (pre-ductal = right hand) signals ductal-level right-to-left shunting.
  • Perinatal asphyxia is a multi-organ disease (redistribution spares brain/heart/adrenals); AKI is often the most sensitive severity marker, and metabolic acidosis on cord/early gas is the objective footprint.
  • Primary energy failure occurs during the insult; a latent phase (therapeutic window) precedes secondary energy failure — which cooling prevents.
  • Resuscitation reasoning: effective ventilation is the cornerstone; heart rate is the readout; escalate by heart-rate response (compressions only after effective ventilation, 3:1).

3. References to Verify

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