Neonatal Anatomy & Physiology Flashcards
What are a normal set of vitals for the newborn?
SBP: 70
DBP: 40
HR: 140
RR: 40-60
What are a normal set of vitals for the 1yr old?
SBP: 95
DBP: 60
HR: 120
RR: 40
What are a normal set of vitals for the 3 year old?
SBP: 100
DBP: 65
HR: 100
RR: 30
What are a normal set of vitals for the 12 yr?
SBP: 110
DBP: 70
HR: 80
RR: 20
Why do neonates have a high alveolar ventilation compared to adults?
They have increased O2 consumption and carbon dioxide production.
What is the primary determinant of cardiac output in the neonate!?
Heart rate
Neonatal heart lacks the contractile elements to adjust contractility or stroke volume
What is hypotension defined as in the newborn?
< 60 mmHg
What is hypotension defined as in the 1 year old?
< 70 mmHg
What is hypotension defined as in a child > 1 years old?
70 + (child’s age x 2) mmHg
Why do stressful situations (DL or suctioning) cause bradycardia in the newborn?
SNS system is less developed. PNS system is not. PNS system takes over.
What is the breathing patterned of the neonate?
Preferential nose breather till 5 mos ~
**bilateral nasal atresia May requires emergency airway management 🚨
How is the tongue in the neonate compared to the tongue in the adult?
Tongue is larger relative to oral cavity
**this makes it more likely to obstruct airway AND DL more difficult
How is neck length in the neonate compared to neck length in the adult?
Short neck ~ more acute angle to DL
How is the epiglottis in the neonate compared to the epiglottis in the adult?
Adult: leaf or c-shaped/ floppy/ shorter
NEONATE: U SHAPED; STIFF, LONGER
***makes it more difficult to displace during DL
How is vocal cord position of the neonate compared to vocal cord position of the adult?
Adult: cords are perpendicular
Neonate: cords have ANTERIOR SLANT ~ passage of ETT may be difficult. ETT may get stuck on anterior commissure ~ also hard for nasal intubations
What is the laryngeal position in the adult compared to the neonate?!
Adult: C5-C6
Neonate: C3-C4
**Larynx is more superior, cephalad, or rostral. IT IS NOT MORE ANTERIOR!!!
Miller blade preferred.
What is the narrowest point in the neonatal airway compared to the adult airway?
Adult ~ glottic opening
Neonate ~ fixed (cricoid ring); dynamic (glottic opening!)
What is the Subglottic airway shape in the neonatal airway compared to the adult?
Adult ~ cylinder
Peds ~ funnel
Where is the right main stem bronchus in the neonatal airway? Where is the bronchus in the adult airway?
Adult: more vertical (takes off at 25 degrees)
Neonatal: LESS VERTICAL (55 degrees) ~ both bronchi take off at 55 degrees until age of 3 years.
What is the intubating position for the adult? What about the neonate?
Adult: sniffing
Peds: head ON BED with SHOULDER ROLL **+infant has large occiput
What is the oxygen consumption of the neonate compared to that of the adult?
Neonate: 6mL/kg/min
Adult: 3 mL/kg/ min
at what age do alveoli stop growing in number?
8-10 years
What is the neonatal alveolar ventilation?
130 mL/kg/min
Why do neonates desaturate so much faster than adults?
Increased ratio of alveolar ventilation relative to the size of FRC
***decreased FRC reflecting a reduced O2 reserve
What type of diaphragm fibers does the neonate have?
More type 2 (fast twitch) ~ short burst of heavy work
Less type 1 [25%] (slow twitch) ~ built for endurance
***neonates are more likely to experience resp fatigue
What is the risk of apnea inversely related to?
Inversely related to post-conceptual age (PCA)
Infants less than what should be admitted for 24 hr observation?
< 60 weeks PCA
Former preterm infants < than what have a greater risk of postoperative apnea than infants > what?
44 weeks PCA
What medication can decrease the risk of postoperative apnea after general anesthesia?
Caffeine (10 mg/kg IV)
How does neonatal chest wall compliance and lung compliance compare to the adult?
Chest walk compliance : ^ d/t cartilaginous rib cage ~ flimsy
Lung compliance: decreased ~ fewer alveoli
What three things does a neonate do to increase their FRC?
Sustained tonic activity of inspiratory muscles
Narrowing of glottis during expiration
Shorter expiratory time with a faster resp rate ~ creates end-expiratory pressure
***these are abolished with general anesthesia and muscle relaxation.
How do the lung capacities differ in the neonate?
FRC: decreased
VC: decreased
TLC: decreased
RV: increased
CC: increased
Tidal volume: same
What is the pH of mother at term?
pH: 7.40
What is the pH of umbilical vein: placenta of fetus?
pH: 7.35
***REMEMBER VEIN IS OXYGENATED IN THE FETAL CIRCULATION
What is the pH of the umbilical artery: fetal placenta?
pH: 7.30
**REMEMBER THIS IS THE UN-OXYGENATED SITE IN FETAL CIRCULATION
What is the fetal pH at 10 mins, 1 hour and 24 hours?
**10 mins: 7.2
1 hour: 7.35
24 h: 7.35
What is the PaO2 of mother at term?
90
What is the PaO2 of umbilical vein?
30
What is the PaO2 of umbilical artery?
20