Pediatric Fundamentals Growth and Development Drs. Greg and Joy Loy Gordon January 2005
Pediatric Fundamentals
Growth and Development
Drs. Greg and Joy Loy GordonJanuary 2005
Pediatric Fundamentals - Growth and Development
Maturational change in form and function
Prenatal GrowthGestational age (wks) Mean birth wt (Gm)
25 85028 100030 140033 190037 290040 3500
Postnatal GrowthBirth weight doubles by 5 months
triples by 1 yearBirth length doubles by 4 years
Pediatric Fundamentals - Growth and Development
Maturational change in form and function
Percent body waterTerm newborn 801 year old 70Adult 60
Surface area:Weightpremature > full term > infant > childgreater surface area
greater evaporative heat lossrapid hypothermia if unprotected
Girls Boys
Puberty onset 11 years 11½ years
Peak growth Tanner stage 3 Tanner stage 4
Pediatric Fundamentals - Growth and Development
Metabolism of one calorie of energy consumes one ml of H2O,
so fluid requirements thought to reflect caloric requirement:
Body weight (kg) Calories needed (kcal/kg/day) = Fluid requirement (ml/kg/day)
0-10 100
10-20 1000 + 50/(kg>10)
> 20 1500 + 20/(kg>20)
Dividing by 24 (hours/day) yields the famous
4:2:1 Rule for hourly maintenance fluid:
4 ml/kg/hr 1st 10 kg +
2 ml/kg/hr 2nd 10 kg +
1 ml/kg/hr for each kg > 20
Fluid requirements
Pediatric Fundamentals - Growth and Development
Airway/respiratory system
Gas exchange first possible approximately 24 weeks gestationSurfactant production appears by approximately 27 weeks
produced of Type II pneumocytesexogenous form available
Number (and size) of alveoli increase to age 8 years(size only after 8 years)
First breaths of airpneumothorax or pneumomediastinum less than 1%several hours to reach normal lower lung fluid levels
some expelled during birth canal compressiontransient tachypnea of newborn (TTN)
increased incidence after C-section
Pediatric Fundamentals - Growth and Development
Respiratory rate/rhythmpauses up to 10 seconds normal in prematures
without cyanosis or bradycardiaAge (years) Normal Rate1 - 2 20 - 402 - 3 20 – 307 - 8 15 - 25
Obligate nose breathing
especially prematures
able to mouth breath if nares occluded
80% of term neonates
almost all term infants by 5 months
Pediatric Fundamentals - Growth and Development
Airway differences – infant vs adultepiglottis and tongue relatively largerglottis more superior, at level of C3 (vs C4 or 5)cricoid ring narrower than vocal cord aperture
until approx 8 years of age 4.5 mm in term neonate11 mm at 14 years
Pediatric Fundamentals - Growth and Development
Cardiovascular system
In utero circulationplacenta ->umbilical vein (UV)-> ductus venosus (50%) -> IVC -> RA ->foramen ovale (FO) ->LA -> Ascending Ao ->SVC -> RA ->tricuspid valve ->RV (2/3rds of CO) -> main pulmonary artery (MPA) ->ductus arteriosus (DA) (90%) ->descending Ao ->umbilical arteries (UAs)->
Pediatric Fundamentals - Growth and Development
Transition to postnatal circulation
Cardiovascular system
Loss of large low-resistance peripheral vascular bed, the placenta
(UV, UAs constrict over several days)
With first air breathing
marked drop in pulmonary vascular resistance with
greatly increased pulmonary blood flow
LA pressure > RA pressure
closes FO
Elevated PaO2 constricts DA
hours to days
Hgb F impairs postnatalO2 delivery
Higher newborn resting cardiac index
with decreased ability to further increase
Pediatric Fundamentals - Growth and Development
Cardiovascular system
Normal murmurs
up to 80% of normal children
vibratory Still’s murmur
basal systolic ejection murmur
physiologic peripheral pulmonic stenosis (PSS)
venous hum
carotid bruit
S3
Murmur only in diastole = abnormal
Pediatric Fundamentals - Growth and Development
Gastrointestinal notes
Gastric pH higher at birth; decreases over several weeksYoung infants
diminished lower esophageal sphincter tone50% have daily emesis (usually remits by 18 months)more show reflux if esophageal pH monitoredonly 1 in 600 develop complications of reflux
Physiologic jaundiceColic < 3 monthsUmbilical hernia
commonfrequently resolve spontaneously
Teethprimary: 7 months to 2 or 3 yearspermanent: 6 years to 20 years
Pediatric Fundamentals - Growth and Development
Renal system
Urine production begins first trimester
Newborn
GFR
low (correlates with gestational age/size in prematures)
rises sharply first 2 weeks
adult values by age 2 years
limited concentrating ability (600 vs adult 1200 mOsm/kg)
ability to dilute urine relatively intact
Pediatric Fundamentals - Growth and Development
Hematologic system
Infant Hgb F – higher O2 affinity
Hgb A production largely replaces Hgb F by 4 months
Hgb/Hct decrease to nadir at about age 2 months
exaggerated in prematures (low total body Fe stores)
Blood volume (ml/kg)
Prematures 105
Term newborn 85
Adult 65
Pediatric Fundamentals - Growth and Development
General pharmacotherapeutic note:
On a per kg basis compared to adults
Expect lower doses in infants and
Higher doses in children
Pediatric Fundamentals - Growth and Development
Neuro notes
Nervous system anatomically complete at birth except:
Myelination
rapid for 2 years
complete by 7 years
Posterior fontanelle closed by 6 weeks
Anterior fontanelle closed by 18 months
Primitive reflexes disappear in few months
Pediatric Fundamentals - Growth and Development
Developmental pediatrics
History and physical notes
Newborn – pregnancy and delivery
Infancy – developmental milestones
Toddler – poor localization of symptoms and very suggestible
(e.g., pharyngitis or pneumonia presenting as
abdominal pain or distress)
Older child – involve in discussion/decision
Preadolescent and older – consider interview without parents
Exam
opportunistic approach in infants and young children
observation essential
distraction useful
Pediatric Fundamentals - Growth and Development
Pediatric Fundamentals - Growth and Development
Pediatric Fundamentals - Growth and Development
Developmental pediatrics
Approach to patient depends on stage of developmentStranger anxiety 7 months 25%
9 50 12 75
Toddlersmagical thinking (belief that own thought or deed causes external events)temper tantrums (aggravated if tired, ill, uncomfortable)
Toilet trainingability develops by 18 monthsusually complete by 2 to 3 years (day before night)bedwetting
15 - 20 % at 5 years with gradual decrease to 1% at 15 years
6 -11 years - concrete operations phasecan consider different points of viewdevelop explanation based on observationbeginning logical reasoning but still tend to dogmatic
11 and older - development of abstract thinkingAdolescent - increasing need for autonomy, participation in care
http://metrohealthanesthesia.com/edu/ped/pedspreop3.htm
Pediatric Fundamentals - Growth and Development
For more info regarding age-related preparation of the
pediatric patient for anesthesia see: