Neonates Part I Flashcards
Define the neonatal period.
- First 28 days of extrauterine life.
Why might anesthesia be required for neonates?
- Life-threatening illness.
- Medical conditions needing surgical intervention.
What types of surgical interventions might neonates need anesthesia for?
- Palliative
- Staged
- Corrective
Why is the neonate particularly vulnerable during the neonatal period?
- Vulnerable to internal and external stressors.
How should the anesthetic plan for neonates be tailored?
- To mitigate physiologic stress
- Improves neonatal morbidity and mortality.
What does anesthetic management of neonates require?
- Specialized knowledge about patients
- Extreme vigilance
- Refinement of technical skills.
Does anesthetic management differ between term and premature neonates?
- Requires integration of specialized knowledge for both term and premature neonates.
How does fetal circulation’s organ of respiration differ from the adult’s?
- Fetal: Placenta
- Adult: Lungs
How is fetal circulation arranged compared to adult circulation?
- Fetal: In parallel
- Adult: In series
What shunting occurs in fetal circulation?
- Right-to-left shunting across the foramen ovale and ductus arteriosus.
Compare the Systemic Vascular Resistance (SVR) between fetal and adult circulation.
- Fetal: SVR is low
- Adult: SVR is higher.
Compare the Pulmonary Vascular Resistance (PVR) between fetal and adult circulation.
- Fetal: PVR is high
- Adult: PVR is lower
Describe the pulmonary blood flow and left atrial pressure in fetal circulation.
- Minimal pulmonary blood flow
- Low left atrial pressure.
What is the purpose of the ductus venosus in fetal circulation?
- Shunts blood from the umbilical vein to the IVC (bypasses liver).
What role does the foramen ovale play in fetal circulation?
- Shunts blood from the RA to the LA (bypasses lungs).
What is the function of the ductus arteriosus in fetal circulation?
- Shunts blood from the pulmonary artery to the aorta (bypasses lungs).
How many umbilical veins are there and what is their function?
- One umbilical vein
- Carries oxygenated blood from the mother to the fetus.
How many umbilical arteries are there and what is their function?
- Two umbilical arteries
- Carry deoxygenated blood from the fetus to the mother.
Why can fetal shunts be problematic during extrauterine life?
- Beneficial in-utero
- Problematic if remain open during extrauterine life.
What is the function of the one umbilical vein in fetal circulation?
- Provides oxygen-rich blood to the fetus.
How does the ductus venosus contribute to fetal circulation?
- Shunts oxygenated blood past the liver
- Saving oxygen for the heart and brain.
Describe the mixing of blood in the inferior vena cava (IVC) in fetal circulation.
- Oxygenated blood from the ductus venosus and deoxygenated blood from the lower body converge, creating two streams of blood at different rates.
What is the significance of the higher velocity of oxygenated blood in the fetal heart?
- Enters the RA and
- Is preferentially diverted across the foramen ovale to the LA
- Perfusing the myocardium and brain.
How is deoxygenated blood directed in fetal circulation?
- Lower velocity blood is directed to the RV and pulmonary trunk
- then shunted via the ductus arteriosus to the descending aorta
- perfusing the lower body and returning to the placenta through two umbilical arteries.
What causes shunting between the pulmonary and systemic circulations?
- Abnormal communication between the pulmonary and systemic circulations.
What factors determine the size and direction of a shunt?
- Ratio of PVR to SVR
- Pressure gradients between cardiac chambers or arteries
- Compliances of the cardiac chambers.
What happens when PVR is greater than SVR?
- Right-to-left (R → L) shunt occurs.
What happens when SVR is greater than PVR?
- Left-to-right (L → R) shunt occurs.
What is a cyanotic shunt and give an example?
- Cyanotic shunt (R → L): Tetralogy of Fallot.
What is an acyanotic shunt and give an example?
- Acyanotic shunt (L → R): Ventricular septal defect.
How does a right-to-left shunt affect anesthesia induction?
- Slower inhalation induction
- Faster IV induction.
How does a left-to-right shunt affect anesthesia induction?
- Negligible effect on inhalation induction rate.
- Possibly prolongs IV induction onset.
What is Eisenmenger syndrome?
- A left-to-right shunt changes to a right-to-left shunt due to pulmonary hypertension.
What is a Cyanotic Shunt (R → L) also known as?
- Known as “Blue Baby.”
What happens in a cyanotic shunt?
- Blood bypasses the pulmonary circulation.
Why does the blood appear blue in a cyanotic shunt?
- Shunted blood does not bind oxygen in the lungs
- Diluting the final PO2 of blood ejected by the left ventricle.
What is an Acyanotic Shunt (L → R) also known as?
- Known as “Pink Baby.”
What occurs in an acyanotic shunt?
- Oxygenated pulmonary venous blood is recirculated through the right heart and lungs
- Instead of being pumped to the body.
What are the consequences of an acyanotic shunt?
- Robs the body of blood flow.
- Overloads the right heart and pulmonary vasculature.
What determines cardiac output in neonates?
- Heart rate.
How do neonates’ oxygen consumption and CO2 production compare to adults?
- Twice as much per weight.
What’s more efficient for neonates, increasing respiratory rate or tidal volume?
- Increasing respiratory rate.
Is stroke volume fixed or variable in neonates?
- Fixed.
How does the neonate’s left ventricle respond to increased afterload?
- By increasing heart rate.
Which part of the autonomic nervous system is less mature in neonates?
- Sympathetic nervous system (SNS).
How do neonates respond to laryngoscopy?
- With bradycardia.
What risk does pain pose in neonates?
- Predisposes to intracerebral hemorrhage.
Up to what age do infants prefer nose breathing?
- Up to 5 months.
How does the size of the tongue in infants compare to their mouth volume?
- Larger tongue relative to mouth volume.
Describe the neck length in pediatric patients.
- Shorter neck.
What is the shape and characteristics of the epiglottis in infants?
- U or omega shape
- Longer and stiffer
How do vocal cords in infants differ from adults?
- Anterior slant.
Where does the laryngeal position correspond in infants?
- C3 - C4.
What is the narrowest fixed region in the pediatric airway?
- Cricoid ring.
What is the narrowest dynamic region in the pediatric airway?
- Vocal cords.
Describe the shape of the subglottic airway in infants.
- Resembles a funnel.
How does the position of the right mainstem bronchus in infants compare to adults?
- Less vertical
- Takes off 55 degrees from midline.
Neonates’ oxygen consumption rate?
- 6 mL/kg/min.
Neonates’ alveolar ventilation compared to adults?
- Increased.
Neonates’ FRC level?
- Slightly decreased.