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
What is the PaO2 of neonate at 10 mins, 1 hr, and 24 hrs?
10 mins: 50
1hr: 60
24hours: 70
What is the PaCO2 of mother at term?
30
What is the PaCO2 of umbilical vein?
40
What is the PaCO2 of umbilical artery?
50
What is the PaCO2 of neonate at 10 mins, 1 hour, and 24 hours?
10 min: 50
1 hr: 30
24 hr: 30
What is the full ABG or a newborn at 10 mins?
pH: 7.2
PaO2: 50
PaCO2: 50
What stimulates the neonate to breathe rhythmically?
Clamping of the umbilical cord AND the acute rise in PaO2
Before maturation (44ish weeks) hypoxemia what?
Depresses ventilation
After maturation (44ish weeks) hypoxemia what?
Hypoxemia stimulates ventilation
What is the P50 of fetal hemoglobin (Hgb F)?
19 mmHg
(Shifts curve to the LEFT) ~ this facilitates a lower O2 partial pressure (increased gradient) and creates passage of O2 from mom to fetus
what does adult hemoglobin consist of?
Two alpha
Two beta chains
What does fetal hemoglobin consist of?
Two alpha
Two gamma
“Gamma is a problamma!” Gamma is unable to bind 2,3 DPG ~ this explains the curve to the LEFT! Higher affinity to oxygen
At what age is Hgb F COMPLETELY replaced by Hgb A?
At six months
at what age does infants have physiologic anemia? Hgb declines to 10 g/dL?
3ish months > months 4 hemoglobin begins to rise
What is the hemoglobin of a neonate at birth?
17 ish
What is the P50 of hemoglobin A? (Like in the adult)
26.5 mmHg
What is the transfusion trigger for a child with severe cardiopulmonary disease?
***child < 4 months
< 13 g/dL
What is the transfusion trigger for a child presenting for major surgery or with a moderate cardiopulmonary disease? ***child < 4 mos
< 10
What is the dose of PRBCs in the neonate?
10 mL/kg
***10 mL/kg will increase Hgb by 1-2 g/dL
What is the dose of FFP in the neonate?
10-20 mL/kg
What is the dose of platelets if by apheresis?
5 mL/kg
What is the dose of platelets from platelet concentrate?
1 pack/10 kg
A single apheresis equals how many pooled platelets?
6-8 pooled platelet concentrates
How much will one pooled concentrate increase serum platelets?
50 x 10^9/L
What are the main complications to massive transfusion in the neonate?
Alkalosis > citrate metabolism to bicarb
Hypothermia > transfusion of cold blood
Hyperglycemia > d/t dextrose additive
Hypocalcemia > bind if Ca by citrate
Hyperkalemia > admin of older blood
How can the risk of hyperkalemia following massive transfusion be reduced for the neonate?
Washed or fresh cells (< 7 days old)
What is the dose for pooled platelets in a child?
1 pack/10kg
What is the normal Hgb in the newborn?
17ish
What is the normal Hgb in the 3 month old?
12ish
What is the normal Hgb in the 6 month-1 year old?
12 ish
What is the normal hemoglobin in the adult female?
14 ish
What is the normal hemoglobin in the adult male?
16isb
How does the neonatal kidney compare to the adult kidney?
Decreased:
Perfusion pressure
GFR
Diluting/contesting abilities
Why is meticulous fluid management so important in the neonate?
They do a poor job of conserving water
BUT also they are unable to excrete large volumes of water
***in addition, they have a HIgH insensible loss. They lose most of the body water through evaporation d/t surface area to body weight ratio (4x higher than the adult)
What is a neonate when think of solutes and the kidney?
Obligate sodium loser
(In addition to glucose too)
When does GFR reach adult levels?
8-24 months!!!
When does tubular function achieve FULL concentrating ability?
2 years
What is the TBW%, ECF and ICF in the premature infant?
TBW% ~ 85
ECF: 60
ICF: 25
What is the TBW%, ECF and ICF in the neonate infant?
TBW: 75
ECF: 40
ICF: 35
What is the TBW%, ECF and ICF in the child/adult?
TBW: 60
ECF: 20
ICF: 40
What does a higher ICF volume (in child and adults NOT neonates) do?
Provides a volume reserve
What are some signs of dehydration in the neonate?
Sunken anterior frontanel
Weight loss > 10% (this is normal in 1st wk)
Irritability
Dry mucus membranes
Decreased skin turgor
Increased hematocrit
What type of children/infants are at risk for developing hypoglycemia?
Premature
Low gestational weight
< 48 hours of age
Newborns of DM mommas
Children with DM
Children who receive glucose based parenteral nutrition
What is the average BBG in which signs of hypoglycemia will show in the neonate?
40 mg/dL
What does treatment of hypoglycemia include?
IV 10% Dextrose (2 mL/kg) bolus
Followed by 8 mg/kg/min titrates to maintain serum glucose > 40
Because neonates have a night total percentage of body water….?
They require higher doses of water-soluble drugs to achieve a given plasma concentration
Because neonates have a faster cardiac output….?
Drugs are delivered and removed from the rest of the body at a faster rate
Because neonates have a lower concentration of proteins…?
Neonates will experience increased free drug levels and have a higher risk of toxicity
Because neonates have a higher total body water and lower % of fat and muscle, drugs that require fat for redistribution and termination…..?
Will have a longer duration of action
At what age are adult value of hepatic metabolism reached?
1 year
Why do neonates have a higher sensitivity to sedative-hypnotics?
Immature BBB
At what age is the MAC for Sevo highest?
About 3 months (3.2)
How does the MAC requirements go in the neonate/child? From least to most
Premature < neonate < infant < 3 month old INFANT (highest)
6 mos -12 years is higher than the adult, but lower than 3 months (2.5)
Why is the dose of non-depolarizing muscle relaxants the same as an adult in a neonate but a dose of depolarizing NMB is increased?
Combo of increased ECF volume and increased sensitivity to nondepolarizers is a wash ~ equal
BUT the increased ECF and SAME sensitivity to sux requires a higher dose
In children less than 5, sux can cause what?!
Bradycardia and asystole
Preoperative atropine may help.
If a child experiences cardiac arrest following Sux, what should be assumed?
Hyperkalemia
🚨 calcium is the first line treatment!!!
What is the IM dose of sux in neonates/infants?
5mg/kg
What is the IM dose of sux in children?
4 mg/kg
What is the ONLY non-depolarizer that can be given in IM route?
Rocuronium
Dose: 1mg/kg (<1 yr) and 1.8 mg/kg (>1 yr)