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Flashcards in Pediatrics Deck (43)
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Neonatal period:


PGA calculation

What is considered low birth rate?

Extremely low gestational age?

  • Neonate is birth to 30 days old
  • PGA =(# weeks gestation at birth) + (current age in weeks)
    • post-op admission for pts <60 weeks PGA
  • Pre-term <37 weeks
  • Low birth rate <2500 grams
  • ELGAN = 23-27 weeks


All pre-term patients have potential for what problems?


  • respiratory distress
  • apnea
  • hypoglycemia
  • electrolyte disturbances (low mg and Ca)
  • infection
  • hyperbilirubinemia
  • polycythemia
  • thrombocytopenia


What are the risks for babies of normal gestation?


former premature up to 60 weeks PGA?

  • Normal gestation: 37-40 weeks
    • congenital anomalies
    • viral infections
    • perinatal depression
    • fetal alcohol
    • thrombocytopenia
  • Postmature: >42 weeks (the above risks +...)
    • meconium aspiration
    • birth trauma if LGA
    • hypoglycemia (esp if mother is diabetic)
    • hyperbilirubinemia
  • Up to 60 weeks PGA
    • post-op apnea and bradycardia (often require 12 hour admission)


Describe fetal circulation

  • oxygenated blood leaves placenta via umbilical vein
  • blood bypasses the liver via the ductus venosus to go straight to the IVC
  • Portion of this blood "Jet streams" straight across Right atrium through Foramen ovale into left atrium to then be pumped through ventricle and aorta
  • *Remaining blood goes normal route to right ventricle and PA.  High pulmonary vascular resistance forces most of this blood through the Ductus arteriosus from PA to Aorta


What are the primary changes that occur to fetal circulation at birth?


  • ductus venosus closes
  • blood is now oxygenated via lungs
  • ductus arteriosus closes (d/t increased arterial O2 concentration)
  • pulmonary vascular resistance decreases
  • peripheral vascular resistance increases
  • foramen ovale closes
    • true closure is weeks later and 25-30% of adults have patent foramen ovale


What is transitional circulation and what causes it?

How can it be prevented?

  • occurs at birth and first several weeks of life
  • hypoxia, hypercapnia, or hypothermia can lead to increased pulmonary artery pressure, reversal of flow through the foramen ovale, re-opening of ductus arteriosus and shunting
    • hypoxia is #1 cause
  • Prevention with optimal oxygenation, correct acidosis, keep pt warm


How does the neonatal cardiovascular system differ?

  • Heart:
    • structurally immature
    • fewer myofibrils
    • sarcoplasmic reticulum immature
    • cardiac calcium stores reduced
  • Ventricles less compliant
    • CO is HR dependent
    • increased preload does not increase SV as much as in an older child
  • Baroreceptor reflex immature in the neonate causing inability to compensate for hypotension with reflex tachycardia
  • Parasympathetic dominance- tendency to brady


What is the resting CO for a neonate at birth?



  • neonate at birth: 400 ml/kg/min
  • infant: 200 ml/kg/min
  • adolescent:100 ml/kg/min


Neonates are vulnerable to problems caused by citrated blood products because __________.


__________ is the preferred treatment of badycardia and decreased cardiac output in pediatric patients.

they are dependent on ionized calcium





How does the neonatal pulmonary system differ?


  • Fewer and smaller alveoli- they increase in number and size up until 8 yo
  • Infants have a small airway diameter and increased resistance
  • Highly compliant airway and chest wall - easy to see retractions
  • Closing capacity is greater than FRC in very young and very old
    • airway closure can occure before end exhalation--leads to shunting and dead space
  • Early fatigue and diaphragmatic and intercostal muscles until age 2 b/c type 1 muscle fibers are not mature
    • neonates have 10%, 2 yr and greater have 55%
  • O2 consumption is 2-3x an adult


Describe the airway anatomy of an infant


  • larger tongue in smaller submental space
  • higher larynx (C2-C4)
  • short stubby (omega shaped) epiglottis
  • angles vocal cords (caudal slant)
  • funnel shaped larynx with narrowest region @ cricoid ring
  • obligate nasal breathers
  • large occiputs that affect sniffing position (use shoulder roll)
  • edentulous
  • short trachea (4-5 cm)
  • angulation of right mainstem bronchus


Airway differences comparing infant to adult



Compare between an adult and neonate: (table)

Oxygen consumption

alveolar ventilation

respiratory rate



How does the pediatric airway affect gas flow?


A 50% reduction in radius increases the pressure ___-fold

  • young children have elevated airway resistance at baseline
    • swelling can have huge impact by increasing resistance
  • Turbulant airflow is present to 5th bronchial division
  • 32-fold


How does the pediatric neurological system differ?

O2 consumption



other things...


  • Oxygen consumption and CBF is about 50% greatr in children than adults
    • adults: 3.5 ml blood flow/100 g brain mass
    • neonates: 5.5 ml/100g
  • Myelinization and synaptic connections not complete until age 3-4 years
  • Rapid brain growth in first 2 years
  • Conus medullaris at L3 at birth, migrates to L1 or L2 by 3 yo
  • Fontanels: anterior closed by 18 months, posterior closed by 2 mo


What does recent research say about anesthesia-induced developmental neurotoxicity?


  • Increased and accelerated neuroapoptosis occurs with virtually all anesthetics
  • Single exposures of short duration are usually of no consequence
  • Repeated and/or prolonged exposures at a young age (<3-4 years) may be associated with later behavioral and learning difficulties
  • ***evidence is inconclusive


What are differences you should consider with neuraxial in pediatrics?

  • The conus medullaris ends at L1 in adults and at the L2-L3 in neonates and infants
  • Iliac crest is even with L4-L5 or L5-S1 interspace (similar to adults) so it is still well below the conus medullaris
  • Dural sac terminates more caudally (S3) in neonates and infants than in adults (S1)
  • Infants have less lumbar lordosis leading to increased risk of high spinal with changes in positioning


How does the renal system change from infancy through childhood?

  • GFR is signifincantly impaired at birth but improves throughout the 1st year
    • premature infants will take longer to reach renal maturation
  • Renal tubular concentrating abilities do not achieve full capacity until about 2 yr
  • Half-life of medications excreted by glomerular filtration are prolonged in the very young
  • During childhood, renal clearance rate may be higher than adult clearance rates
    • drug half life is shorter that adults for kids >2yr


How is liver function different in pediatrics?

  • Enzyme systems are still developing up until 1 yr
  • At birth Phase I Cytochrome P450 system is 50% of adult values and Phase II (conjugation reactions) are impaired in neonates
    • Causes longer half life on BZD and morphine
    • deceased bilrubin breakdown d/t reduction in glucuronyl transferase (also affects tylenol metabolism)
  • Hepatic synthesis of clotting factors reach adult levels withing one week of birth
  • Lower levels of albumin and other proteins for drug binding in newborns--> causes larger proportion of unbound drug and increased effects
  • Minimal glycogen stores- prone to hypoglycemia


How does the GI system differ in pediatrics?

  • Coordination of swallowing with respiration is not mature until 4-5 months of age 
    • causes high incidence of reflux
  • Gastric juices are less acidic up to about 3 years
  • Absorption of oral medications is slower compared to adults
  • GI tract is slower (slower emptying time)


What is the significance of thermoregulation in pediatric patients?

< 3 months old?

factors that contribute?

  • They have large body surface area to weight ratio
  • lack subq tissue for an insulator
  • < 3 months:
    • inability to shiver
    • metabolize brown fat to increase heat production
    • can lead to metabolic acidosis and increased O2 consumption
  • Factors that contribute:
    • cold OR
    • anesthetic-induced vasodilation
    • room temp IV fluids
    • evaporative heat loss from surgical site
    • cold irrigating solutions
    • cold anesthetic gases


What are the ways heat is lost in the OR?


  1. conduction
  2. evaporation
  3. convection
  4. radiation


How can you actively warm a pediatric patient?

  • warming mattress
  • incubator
  • cover with blankets
  • head coverings
  • transport in isolette
  • humidify gases
  • use plastic wrap on the skin
  • warm prep and irrigation solutions
  • change wet diapers and remove wet clothing
  • Forced air warming **most effective strategy for childre >1 yr**


How should you monitor temp?

How should you not?

What are some problems that hypothermia can cause?

  • Core temp is best (esophageal)
  • Axillary temp can recognize MH earlier
  • NO Forehead temp!  10 MH episodes unrecognized w/forehead temp
  • Hypothermia:
    • delayed emergence
    • reduced degradation of drugs
    • increased infection


How does body composition vary over the age spectrum?


*know trends, not actual numbers


How does the difference in body composition affect anesthesia?

  • Higher total body water:
    • Water sluble drugs have a larger volume of distribution
      • need a larger initial dose (sch, abx)
      • larger distribution can delay excretion
  • Neonates have less fat and muscle
    • drugs that depend on redistribution to fat for termination of action will have prolonged effects
  • Protein binding: <6 mo have less albumin and alpha-1 acid glycoprotein (AAG)
    • higher free-fraction of protein bound drugs
    • free fraction of local anesthetics will be higher (bind to AAG)


In general, most medications will have a _______ elimination half-life in pre-term and term infants, a _______ half-life in children older than 2 yrs up to early teen years, and a ________ of half-life in those approaching adulthood.

In general, most medications will have a prolonged elimination half-life in pre-term and term infants, a shortened half-life in children older than 2 yrs up to early teen years, and a lengthening of half-life in those approaching adulthood.


How do you calculate maximum allowable blood loss (MABL)?


How does fetal hgb differ from adult hgb?

Target hct for neonates?

  • Fetal Hgb has a lower P50 at 19 mmhg compared to 26 mmHg in adults
    • LEFT shift
  • Target HCT is higher in neonates d/t L shift and decreased CV reserve
    • minimum HCT of 40% instead of 30%


What is the expected hgb and hct for: (table)


3 mo***

6-12 mo

adult female

adult male

*** physiologic anemia at 2-3 mo