Case 82 - neonatal resucictation

Question 1

Describe the fetal circulation

Answer 1

• gas exchange occurs at placenta
  
  • oxygenated blood - PaO2 of 30-35 mmHg
• umbilical vein carries oxygenated blood from placenta to fetal circulation
• the oxygenated blood from placenta ​bypasses liver via ductus venosus and travel to RA –> PFO to LA
• deoxygenated blood from SVC (drains head and neck) will be directed to RV –> PA –> ductus arterosis
• blood in aorta will flow to tissues, become deoxygenated and flow back to placenta for gas exchange via umbilical arteries (2 arteries)

High PVR, low SVR

Question 2

What physiologic changes occur at birth?

Answer 2

1) Decrease PVR
* first breath -> lung expansion -> inc Alveolar PaO2
2) increase SVR
* clamping umbilical cord and removal of placenta (low-resistance system) results in inc SVR

Shunts

foramen ovale

• inc SVR leads -> inc LV pressure -> inc LA pressure -> functional closure of foramen ovale

ductus arteriosus

• inc PaO2 2/2 lung expansion and inc alveolar PaO2 leads to functional closure of ductus art

Question 3

why is neonatal circulation sometimes referred to as transitional circulation?

Answer 3

• once fetus is born, there circulatory system begins to resemble an adult circulation
• functional closure takes time for complete closure
• states that increase PVR will reverse the functional closure of shunts and make them patent:
  
  • ​hypoxemia, hypercarbia, acidosis, hypothermia, sympathetic stimulation,
  • persistent pulm HTN of newborn (RDS, congenital diaphragamtic hernia)

Question 4

baby is born, initial APGAR is 2, what will you do?

Answer 4

Newborn resucitation

4 steps: initial steps, ventilation, chest compressions, admin of epi and volume expansion

1) Initial steps

Term gestation? breathing or crying? good tone?

• Yes - routine care: provide warmth, clear airway if necessary, dry, continuous eval
• No - warm, suction airway, dry, stimulate

2) Is HR < 100, gasping or apnea?

• Yes - PPV and preductal SpO2 monitoring
• No - supportive care (clear airway, CPAP?)

3) Is HR still < 100 or now < 60

• HR 60-100 - continue PPV
• HR < 60 - chest compressions, PPV, consider intubation

4) is HR still < 60

• yes - IV epinephrine, consider hypovolemia or pneumothorax

Notes

• PPV - 40 to 60 bpm
• HR - check via stethoscope or palpation of umbilcal artery
• intubation - consider in nonvigorous newborn with meconium staining, when chest compressions occur, ineffective bag mask ventilation, cong diaph hernia
• epi dose - 1:10,000 0. 01 - 0.03 mg/kg IV
• CPR - 3:1 ratio, or 1 minute = 90 compressions: 30 vent

Question 5

What should be the oxygen administration during neonatal resucitation?

Answer 5

• 100% FiO2 can be detemential in neonatal resucitation outcome.
• initial oxygen concentration used may be air or blended oxygen, and oxygen concentration is titrated to target preducatal saturation for age
  
  • ​if HR is <60 bpm after 60 sec of adequate ventilation, then use 100% oxygen

Question 6

How would you manage a neonate when meconium is present?

Answer 6

• tracheal suctionioning still controversial
• is neonate vigorous, breathing, crying, good tone?
  
  • yes, observe
  • no - tracheal suction and monitor HR
    
    • if there is persistent bradycardia, abort tracheal suction and go to neonatal resucitation protocol

Question 7

what is APGAR score?

Answer 7

• assessed at 1 and 5 minutes
• APGAR = appearance (color), pulse, grimace, activity, respirations
• one should NOT wait until 1 minute after birth to begin resuscitative efforts.