Neonate Anesthesia Flashcards
What time span of life defines “neonate”
Birth to 28 days
Why are preterm infants more prone to respiratory complications? What does this mean for post-operative care? What defines preterm birth?
Immaturity of lung tissue and pathology; bronchopulmonary dysplasia. Immaturity of hypoxic response in the brain.
Premature infants and neonates are more prone to poser operative respiratory complications
Birth before 37 weeks gestation is considered preterm birth
What is the difference between PVR and SVR in utero and after birth?
In utero PVR is high and SVR is low, this favors blood flow to the placenta. At birth SVR increases and PVR decreases favoring blood flow to the lungs of the infant.
What major ducts exist in utero that allow for fetal blood flow?
Patent ductus arteriosus between the aorta and pulmonary vein, patent ductus venosus that shifts blood away from the liver, and the foramen oval that allows for bypass of the RV by allowing blood flow from the LA —> RA.
What promotes closure of the PDA in a neonate? What promotes closure of the Foramen Ovale?
The PDA closes in response to shifting blood flow patterns and lack of prostaglandin found with maternal/placental perfusion. Higher SVR pressures and increasing LA pressures prevent blood from the RA to the LA closing off a flap existing between the chambers in utero
Why is pulmonary HTN detrimental to hemodynamic stability in the neonate?
Pulmonary HTN creates high PVR and can promote cyanotic flow (R to L shunt) by maintaining a patent PDA and Foramen ovale
What factors most influence PVR in the neonate? How can these be prevented specifically?
Oxygenation, pH, temperature, stress. Provide good oxygenation and ventilation to avoid hypoxia and acidosis, avoid hypothermia (warming), avoid pain, avoid shivering.
Speak to the concerns regarding HCT in the neonate? What HCT value is ideal and why?
A HCT of around 30% is ideal. If HCT is to high it can cause increased viscosity and increase PVR. Furthermore, low HCT can result in poor oxygenation and also provoke an increase in PVR.
Why are neonates said to be “heart rate dependent”? Where do they operate on the frank-starling curve?
Neonates hearts have fewer myofibrils and respond less to preloading, they are said to already operate at the top of the Frank starling curve. This being the case, cardiac output is influenced less by contractility and preloading and more by HR (CO = HR x SV).
What medication(s) are best to address a decrease in CO in the neonate?
Atropine is often used as it will increase HR (and thus increase CO). Epinephrine is another acceptable, and possibly preferred, intervention as epinephrine will increase HR and promote contractility.
Is the heart of the neonate predominantly driven by the sympathetic or the parasympathetic nervous system? What does this mean for the hemodynamic stability of the neonate?
Neonates are predominately parasympathetic driven. This means that interventions such as laryngeal suctioning and laryngoscopy can lead to bradycardia.
Since neonates already operate at the top of the frank starling curve, does this mean that increasing preload via fluid is not useful for increasing CO? Explain
No. While increasing preload will not result in the same response as an adult heart, it is still prudent to ensure good preload (fluid status) in the midst of sufficient contractility and HR to promote a good CO
What factors will impair contractility of the heart in the neonate? What factors may increase SVR and thus reduce CO in the neonate?
Acidosis, hypoxia
Acute increases in SVR will reduce CO, this may be caused by acidosis, hypothermia, light anesthetic level, pain, etc.
How is hypotension defined in the neonate? What is a normal BP in the neonate?
SBP < 60 mm Hg
SBP of 70-75 mm Hg
What is a normal HR for a neonate?
120-160 bpm
