Anesthesiology APPLIED Exam › Pediatric and neonatal

Neonatal physiology and resuscitation

Pediatric and neonatal·~5 min read· Physician-reviewed✓ Sourced · 2

Stem

You have just delivered a term infant, 3.2 kg, by emergency cesarean under general anesthesia for placental abruption. The mother is stable on the table. The baby is limp, apneic and pale, with a heart rate of 70 by auscultation. The pediatric team has been paged but is not yet in the room, and a nurse brings the baby to the radiant warmer.

Question

How will you resuscitate this baby?

Ideal answer

HeadlineMother stable: I call for help and go to the baby once a qualified anesthesia colleague has her. Bradycardia is hypoxic until proven otherwise; effective ventilation fixes almost every arrest.

Warm, dry, stimulate, position, then PPV within 60 seconds. Apneic, heart rate below 100: 30–60 per minute, 21% oxygen as he is term;¹ preductal oximeter, right hand.
Rising heart rate proves effective breaths. If not: mask, reposition, suction, open mouth, pressure up, then tube or laryngeal mask.²
Still below 60: compressions 3:1, 100% oxygen, after 30 seconds of chest-moving ventilation.
Then epinephrine 0.02 mg/kg IV, about 0.06 mg for 3.2 kg, through an umbilical venous catheter.¹
Abruption means hemorrhage, so volume: 10 mL/kg, about 30 mL, saline or O-negative blood.

Watch for: temperature 36.5–37.5 °C throughout,¹ and glucose once stable.

Breaking down the answer

Physiology drives the plan — oxygen consumption of 6–8 mL/kg/min with closing capacity above functional residual capacity desaturates in seconds; the stiff ventricle makes output rate-dependent; the kidney cannot handle a sodium load; glycogen runs out in hours.
Oxygen by gestation — 21% at 35 weeks or more, 21–30% at 32–34 weeks, 30–100% below 32 weeks,¹ titrated to preductal targets (table).² Hyperoxia injures preterm retina and lung, 100% does not speed recovery; I titrate down once compressions stop.¹
Why 3:1 — 90 compressions and 30 inflations a minute, because the arrest is respiratory; two thumbs with hands encircling the chest, a third of the anteroposterior diameter, reassessing every 60 seconds.¹
Epinephrine range and routes — 0.01–0.03 mg/kg IV via the umbilical vein, the preferred route, every 3–5 minutes; endotracheal 0.05–0.1 mg/kg bridges while access is obtained.¹ Volume is for suspected hemorrhage: abruption or a cord accident.
Temperature tools — radiant warmer, plastic wrap and a cap for preterm infants, warmed gases,¹ because cold raises pulmonary vascular resistance and reverts the circulation. Therapeutic hypothermia is a deliberate neonatology decision for encephalopathy after 36 weeks.
Fitness for the operating room — glucose above 45 mg/dL, a corrected acidosis, an echo for any murmur or cyanosis, and warmed, dextrose-containing fluids; a non-emergent case waits until these are met.

Follow-up question

Two days later the baby comes to the operating room for an emergency laparotomy. He is pink on ventilation, then becomes cyanotic and bradycardic at incision as the room cools. What is happening, and what do you do?

Follow-up answer

HeadlinePersistent pulmonary hypertension with right-to-left shunting through ductus and foramen ovale; I confirm a preductal-postductal gap and tell the surgeon to pause.

I treat the triggers: 100% oxygen, hyperventilation to a PaCO2 of 30–35 mmHg, correction of acidosis, warming the room and the baby, and deeper anesthesia or opioid to blunt the stress response. If it persists, inhaled nitric oxide, and an inotrope for the right ventricle rather than a pure vasoconstrictor. I reassess the saturation gap, heart rate and temperature before the surgeon resumes.

Pitfalls that cost points

Reaching for 100% oxygen as the first step in a preterm infant.
Reciting neonatal physiology as a list without tying each item to a management decision.

Rapid-fire

Q: Why is cardiac output rate-dependent? A: The immature myocardium has fewer contractile elements and poor compliance, so stroke volume cannot rise; bradycardia is a direct fall in output.

Q: Why do neonates become hypothermic? A: A large surface-to-mass ratio, thin skin, little fat and no shivering; non-shivering thermogenesis burns brown fat and oxygen the sick neonate cannot spare.

Q: Why does the circulation revert? A: Hypoxia, acidosis and cold raise pulmonary vascular resistance above systemic, and the open ductus and foramen let blood bypass the lungs.

Q: A neonate is lethargic or seizes after a long fast; what do you give? A: Dextrose 10% at 2 mL/kg, then a continuous infusion.

Numbers to know

Item	Value
PPV trigger	Heart rate <100/min or apnea after initial steps; 30–60 inflations/min¹
Compressions	Heart rate <60/min after 30 s of effective PPV; 3:1, 90 compressions + 30 inflations/min¹
Epinephrine	0.01–0.03 mg/kg IV (0.1 mg/mL) every 3–5 min; ET 0.05–0.1 mg/kg¹
Volume	10 mL/kg saline or O-negative blood
Preductal SpO2 targets	65–70% at 2 min, 80–85% at 5 min, 85–95% at 10 min²
Hypoglycemia treatment	D10 2 mL/kg, then 4–6 mg/kg/min infusion
Target temperature	36.5–37.5 °C¹

Sources

1.2025 American Heart Association and American Academy of Pediatrics Guidelines for CPR and ECC, Part 5: Neonatal Resuscitation · AHA/AAP, 2025 · cpr.heart.org
2.Neonatal Resuscitation Algorithm (2025) · AHA/AAP, 2025 · cpr.heart.orgSource of the preductal SpO2 target table (2 to 10 minutes); the 2025 table has no 1-minute row.

Facts on this page were checked against these sources on Oct 14, 2026. Guidelines change; confirm doses against current institutional protocols.