anesthetic implications and pediatrics

1. PEDIATRIC ANESTHESIA
CHAPTER REVIEW
Shridevi Pandya Shah MD
Dept of Anesthesiology
Rutgers NJMS

3. •Children are not short adults
•Babies are not short children

4. What makes pediatric anesthesia different
from adult
• Neonatal physiology
• Drug dosing
• Airway
• Premeds/psychology
• Consent
• Types/lengths of surgeries
• IV fluids
• Concern about apoptosis

5. Normal developmental milestones
Milestones –conjugate gaze: 4 months,
head up: 3-4 months,
sits with support: 7 months,
walks with one hand: 12 months
separation anxiety: 6-12 months,
first words 9-12 months
Childhood fears: 6 moths to 4 years: separation, postop emotion, cognitive development
Toddlers: 4-8 years separation, magical thinking, body integrity
Children 8 years to adolescents- pain, mutilation, loss of control, fear of not waking up during
surgery
Adolescents: anxiety, body image, physical appearance, fear of unknown
Abnormal cognitive signs : 1 mo-failure to respond to environment, at 5 mo- failure to reach objects,
6 mo-absent babbling,
7 mo-absent stranger anxiety, 11 mo- inability to localize sounds

6. Developmental milestones-classified
• Milestones –motor skills: supporting head at 3 months, sitting alone at 6
months, standing alone at 12 months, balances on one foot at 3 years
• Fine motor skills include grasping rattle at 3 months, passing cube hand to
hand at 6 months, pincer grasp at 1 year, imitating vertical line at 2 years,
and copying circle at 3 years
• Language milestones include squeals at 1.5 to 3 months, turns to voice at 6
months, combines two words at 1.5 years, composes short sentences at 2
years and gives entire name by 3 years
• Social milestones include spontaneous smile at 3 months, feeding crackers
to self at 6 months, drink from cup by one year and playing interactive
games at 2 years

7. Age group classification
• Preterm – less than 37 weeks
• Neonates- 0-1 month
• Infant 1-12 months
• Toddlers- 3-36 months
• Little kids- 3-6 years
• Big kids- 7-12 years
• Adolescents - 13-18 years

16. Preoperative interview
• NPO
• Birth history
• Milestones
• Family history
• Recent URI
• Airway

17. NPO guidelines
• Clear liquids : up to 2 hours before surgery
• Breast milk :up to 4 hours before surgery
• Infant formula : up to 6 hours before surgery
• Solid food (includes , candy, soy, thickened formula): 8 hours
• ?chewing gum
• G-tube feeding : 8 hours ,except for age less than 1 year -6 hours

18. Specific perioperative systemic considerations
• Cardiovascular
• Respiratory
• Renal
• Hepatic
• coagulation
• Neuromuscular
• Central nervous system/spinal cord

19. Cardiovascular system
• C.O at birth-220-350 ml/kg/min, due to greater metabolic rate,
increased oxygen consumption
• Fewer muscle cells than adult heart, more connective tissue than
adult heart
• Contractile element 30% neonate vs 60% adult heart mass
• Sarcoplasmic reticulum and T tubule system incomplete so ionized
calcium transport immature

20. Cardiovascular system
• Limited response to volume loading
• Cardiac output rate dependent-sensitive to negative inotropic and
chronotropic drugs
• Prasympathetic predominance-Atropine becomes choice of
vasopressor
• EKG predominant RV

21. Circulating Blood volume
• Preterm – 90-100 ml/kg
• Term to 3 months 80-90 ml/kg
• Children above 3 months old- 70 ml/kg
• Very obese child 65 ml/kg

22. Accepted range of blood pressure
• Up to age of 38 weeks, it is gestational age in weeks
• Up to age 2, age/2+70 – for systolic

23. Classification of congenital heart disease as
per pathophysiology
• Volume overload- left to right shunt at any level-ASD, VSD, CAVC, TA
• Obstruction to systemic blood flow-often ductal dependent-critical aortic
stenosis, coarctation, interrupted aortic arch, HLHS
• Obstruction to pulmonay blood flow-often ductal dependent-critical
pulmonary valve stenosis, TOF, PA
• Parallel circulation-dependent on mixing at atrial, ventricular or level of
great vessels-D-transposition
• Single ventricle-very heterogeneous group : complete mixing of systemic
and pulmonary venous blood-tricuspid atresia, HLHS, DORV, heterotaxy,
unbalanced CAVC
• Myocardial disorders-primary or acquired-cardiomyopathies etc

24. • Cyanotic Acyanotic
Right to left shunts left to right shunt
• Tetralogy of fallot 10% VSD 20-25%
• Pulmonary atresia 1% ASD 5-10%
• Tricuspid atresia 1% endocardial cushion defect 4-5%
• Complex mixing lesions PDA 5-10%
Transposition of great vessels 5% Obstructive lesions left sided
• Total anomalous pulmonary venous return 1% coarctation of aorta 8-10%
• Truncus arteriosus 1% aortic stenosis 5%
• HLHS 1%
• Double outlet right ventricle 1%
• Obstructive lesions (right sided)
• Pulmonary stenosis 5-8%
•

25. Respiratory system-structural differences
• Small airway diameter-increased resistance
• Little support from the ribs
• Diaphragm and intercostal muscles do not achieve type-1 adult
muscle fibers until age 2
• Obligate nose breathers
• Ribs are horizontal in neonates
• Ribs and cartilages are more pliable
• Chest wall collapse more with increased negative intrathoracic
pressure

26. Respiratory system
• Most importantly
• Alveolar ventilation/FRC
• adults 1.5:1
• Infants 5:1
• Reduced FRC
• Reduced number of alveoli
• Oxygen consumption twice that of adults

27. Why infants are prone to periop hypoxia
Mechanism of continuous neonatal breathing
-the onset of breathing activities occurs in
utero as a part of normal fetal development
-clamping of the umbilical cord initiates
breathing
-relative hyperoxia with air breathing
compared with low fetal paO2 augments
and maintains continuous and rhythmic
breaths
-continuous breathing is independent of
levels of CO2
-breathing is unaffected by carotid
denervation
-hypoxia depresses or abolish continuous
breathing
• Immature respiratory control
• Irregular breathing
• Hypoxia depresses ventilation further
• Trace anesthetics abolish hypoxic
ventilatory response
• Small FRC and higher oxygen demand
• Anesthesia reduces FRC, leading to
airway closure and atelectasis
• High oxygen affinity of fetal
hemoglobin

28. Child with recent URI

30. Renal
• In utero- urine is produced at 10-12 weeks and helps maintain
amniotic fluid volume
• Nephrogenesis complete by 32 weeks gestation
• Tubular function develops by 34 weeks and continues until 2 years
• Decreased tubular threshold for NA,HCO3 and glucose – at risk of
hyponatremia, glucose diuresis and metabolic acidosis

31. Renal
• GFR 20-25% of adult values at birth, unable to excrete large salt load
or effectively concentrate urine
• Obligate salt losers
• Immature distal renal function and relative hypoaldosteronism, poses
hyperkalemia risk
• Adult function achieved by 2 years

32. Hepatic
• Gluconeogenesis and protein synthesis begin 12 weeks GA
• Large glycogen stores in liver toward end of pregnancy
• Alpha fetoprotein first appear at 6 weeks and peak at 13 weeks ,
higher levels associated with neural tube defects, spina bifida,
esophageal atresia, omphalocele and gastroschisis

33. Hepatic
• Converts drugs from less polar to more polar state
• Phase I- CYTOCHROME FAMILY-all not present at birth- oxidation,
reduction, hydrolysis
• Phase- II- conjugation – glucuronidation, sulfation, acetylation
• Phase I- CYP3A,CYP1A2,CYP2D6,CYP2D9
• CYP1A2-Caffeine,CYP3A4-diazepam,CYP2C9-NSAIDS,CYP2D6- codeine

34. Hepatic
• Phase II- conjugation reactions increase hydrophilicity to facilitate
renal excretion
• Glucuronidation- not present at birth resulting delayed metabolism of
morphine, propofol, bupivacaine, dexmedetomidine
• GENETIC variations:
• Single nucleotide change or polymorphism alter CYP activity
• Codeine affected by normal, rapid or slow metabolizers

35. Coagulation
• Vitamin K dependent factors – II,VII,IX,X are 20-60% adult values at
birth
• Result : elevated PT and PTT
• Despite vit k administration at birth it may take several weeks to
achieve adult values
• Neonatal risk is increased when mother is on-
• Anticonvulsant therapy, warfarin, rifampin, INH

36. Neuromuscular system
• Preterm-10% type I fibers, increase to 25% at term and 55% at 2 year
• Type I fiber more sensitive to NMBDs than II
• Diaphragm function preserved and recovers faster than peripheral
muscles in neonates
• Infants need increased dose secondary to more polar nature of
NMBDs, have wider Volume of distribution
• Dose decrease in neonates due to immaturity of neuromuscular
junction

37. Central nervous system
• BRAIN- two growth spurts
• Neuronal cell multiplication 15-20 weeks gestation
• Glial cell multiplication 25 weeks until 2 years
• Myelination nearly complete by 3 years but continues into
adolescence

38. Spinal cord anatomy
• Tip of spinal cord ends at L 3 in neonates
• Cauda equina extends from L2 to S 5
• Dural sac in the neonate ends at S 3 -4 .(S2 in adult)
• Volume of CSF- 10-12 ml /kg in preterm, 12-14 ml/kg in term, 2-4
ml/kg in child and 1-2 ml/kg in adult

39. Apoptosis
• measured as defects in learning, spatial memory, social memory,
spontaneous motor activity, attention or behavior.
• Most human studies are retrospective, contaminated by sampling
errors, biases, old anesthetics, old monitoring strategies and limited
follow up.
• There are no studies in humans that directly link anesthesia to brain
damage
• Two current studies underway- GAS and PANDA

40. Developmental pharmacokinetics
• Blood brain barrier- increased permeability, small molecules and
unbound drugs cross fetal/neonatal blood brain barrier than adults
• Incomplete myelination facilitates hydrophilic drugs
• Hydrophilic drugs have decreased blood conc secondary to larger
volume of distribution secondary to increased body water
• Lower albumin levels and alpha 1 acid glycoprotein levels in neonates
– affects local anesthetics conc and metabolism

41. Inhaled agents – why preferred
• Increased ventilation to FRC ratio- in neonates it is 5:1, in adults 1.5:1
• Increased cardiac output-18% CO perfuses the VRG, whereas in adults
only 6%
• Decreased blood solubility, decreased tissue solubility

42. Inhaled agents and things to remember….
• Washing in of inhaled agents faster –increased alveolar ventilation to FRC
ratio 5:1 vs adults 1.5:1, secondly CO is increased in neonates 18% of CO
perfuses vessel rich group in neonates vs only 6% in adults
• Compound A is produced by sevoflurane during low FGF, CALCIUM ONLY
ABSORBENT-AMSORB prevents formation of compound A
• FLUORIDE TOXICITY- Plasma fluoride levels don't correlate with renal
damage after sevoflurane
• Carbon monoxide toxicity mostly associated with desiccated absorbent
combined with desflurane, isoflurane or enflurane
• BIS- not indicated..may be a trend indicator
• Emergence delirium : incidence 15-25% in age group 2-8 years with sevo

43. Fluid distribution

46. Hemoglobin

47. Hemoglobin related facts

48. Common initial doses of blood components
and expected effect
• Component dose effect
• PRBC 10-15 ml/kg increase HgB by 2-3 g/dl
• Platelets 5-10 ml/kg increase count by 50-100/cmm
• FFP 10-15 ML/KG increase factor level by 15-20%
• Cryoprecipitate 0.1-0.2 units /kg increase fibrinogen by 60-100
mg/dl

49. Thermoregulation
• Large body surface to weight ratio
• Scalp is 20% skin but 85% of heat loss
• Thin layer of subcutaneous fat
• Brown fat generation of heat, norepinephrine mediated
• Brown fat –scapula, and upper part of spine

51. Mechanisms (by Percent) of Heat Loss for a
Neonate in a Thermoneutral Environment
Radiation 39%
Convection 34%
Evaporation 24%
Conduction 3%

52. Perioperative Antibiotic prophylaxis
recommendations
• Cardiac conditions associated with the highest risk of adverse outcome
from endocarditis for which prophylaxis with dental procedures is
reasonable
• Prosthetic cardiac valve or prosthetic material used for cardiac valve repair
• Previous endocarditis
• Congenital heart disease-unrepaired cyanotic heart disease including
palliative surgeries and conduits
• Completely repaired CHD with prosthetic material or conduits whether
placed by surgery or catheter insertion during first 6 months after repair
• Repaired CHD with residual defects in the site or adjacent to a site of a
prosthetic patch
• Cardiac transplant recipients who develop cardiac valvulopathy
• Except for conditions listed above, antibiotic prophylaxis is not
recommended for any other form of CHD

53. Recovery room challenges
-include but not limited to pain management
-PONV
-emergence delirium

54. PONV

56. Emergence delirium
• PAED SCALE ( pediatric anesthesia
emergence delirium scale )
• 1. the child makes eye contact with the
care giver
• 2. the child’s actions are purposeful
• 3. the child is aware of his/her
surroundings
• 4. the child is restless
• 5. the child is inconsolable
• Items 1 to 3 are scored 1 thru 4 in reverse
i.e. 4- not at all.
• Items 4 and 5 scored as 0= not at all and
so forth…threshold for ED more than 10
or 12

58. Airway difference
• Large tongue, large head
• Higher located larynx (C3,C4)
• Epiglottis short and stubby, angled over the inlet
• Angled vocal cords , need to rotate ETT to correct lodging at anterior
commissure
• Narrowest portion is cricoid cartilage

59. ETT size /depth during intubation determination
• Oral uncuffed dia-age/4 + 4 or (4.5)
• Oral cuffed ida :1/2 size smaller than cuffed
• Premies less than 1500 gm, 2.5 cm
• More than 1500 gm, 3.0 cm, term 2.0 cm
• Nasal tubes length: oral tube length + 2 cm
• Length: 10 cm in neonate, 10+ age or age/2+12

60. Head position for intubation

61. Syndromes commonly associated with difficult
airways
• Pierre robin syndrome
• Goldenhar syndrome
• Treacher Collins syndrome
• Hurler syndrome
• Hunter syndrome
• Beckwith-wiedemann syndrome
• Crouzon syndrome
• Down syndrome
• Apert syndrome

63. General considerations for perioperative period
• Preoperative assessment : NPO, detailed history, birth history, general exam ,systemic exam
• Airway –history, dysmorphic features, maximum mouth opening, flex and extend neck
• Induction techniques and equipment
• Fluids : large extracellular water in preterm and term infants. Greater water content means larger volume of
distribution and larger loading dose –for water soluble drugs
• Fluid management : sodium load with 4:2:1 formula, hyponatremic IV fluids, monitoring blood loss and
coagulopathy,
D10 +/- calcium for neonates
Thermoregulation : neonates are poikilotherms... Role of brown fat, thermoneutral zone 32-35 C
Regional anesthesia : differences are anatomic(differential growth of spinal cord and spinal column), physiologic
(high CO and hyperdynamic circulation)and neurocognitive (awake block is not an option), pharmacodynamic (low
levels of alpha I acid glycoprotein ), pharmacokinetic (immature hepatic function )

64. Obtaining consent
• Parental/Legal guardian
• Assent
• Informed Consent
• Emancipated minor

65. Monitored Anesthesia Care-MAC
Is a physician service
distinguished from moderate sedation by
• 1) assessment and management of patient’s actual or anticipated
physiological derangements that might occur during the procedure
• 2)provider must be qualified and prepared to convert to GA
• 3) provider must be qualified to ”rescue a patient’s airway from
sedation induced compromise”

66. Assessment during sedation
• Minimal – responds normally to verbal commands
• Moderate- responds purposefully to verbal commands and light
touch
• Deep sedation- responds purposefully to repeated or painful stimuli
• General anesthesia- unarousable to painful stimuli or reflex
withdrawal
• Deep sedation and general anesthesia – both pose risk of respiratory
depression and cardiovascular collapse

67. Guidelines for sedation
• Advanced airway skills are now mandated by JCAHO,AAP,ASA
Rescue
AIRWAY…AIRWAY…AIRWAY….AIRWAY… AIRWAY…..
Concept: if intended level is minimal sedation, provider must be skilled
to rescue from moderate sedation

68. Sedation guidelines
• Guidelines for the elective use of conscious sedation, deep sedation
or general anesthesia
• Source:*pediatrics 76: 317,1985
• Prompted after 3 deaths in one pediatric dental office
• This guide line was not followed due to misleading title
• Guide lines for monitoring and management of pediatric patients
during and after sedation for diagnostic and therapeutic procedures
• Source *pediatrics 99:1110-1115,1992
• (second AAP version)- the title now reflects the intent of the
document

69. • Fourth AAP guidelines-Guidelines for monitoring and management of
pediatric patient during and after sedation for diagnostic and
therapeutic procedures: an update, Source: *pediatrics 118:2587-
2602.2006.
• Changes-Applies to all venues including office practices
• Recognition that children older than 6 years usually require deep
sedation, warn about nutraceuticals and drug interactions on
cytochrome system, training in and maintenance of advance pediatric
airway skills is required, encourages use of capnography

70. Pain management
Response to noxious stimuli
by 26 weeks of gestation
What is hazard of not treating
pain
Neonates subjected to
repeated noxious stimuli may
have lower cortisol responses

71. MULTIMODAL PAIN
MANAGEMENT
OPIOIDS
NONOPIOID ANALGESICS
IV ACETAMINOPHEN
FDA approved for age above 2 years
NONPHARMACOLOGIC
24%sucrose for neonates
Cuddling, stroking, massage, rocking
Parental presence in PACU
Older children cognitive measures
Distraction, guided imagery, relaxation,
breathing

72. Pain scale
Challenging
Need different assessment
tools
Self reporting one most
reliable –to be taught preop
Validated pain scales include
Visual analog
Faces scale
0-10 numeric
OUCHER

74. Special considerations/disease states
• Retinopathy of prematurity
• Prematurity and apnea
• Malignant hyperthermia and muscular dystrophies
• OSA and sleep disordered breathing/Recent URI
• Trisomy 21
• Neonatal conditions-pyloric stenosis, duodenal atresia, NEC,
omphalocele, myelomeningocele/cerebral palsy/craniosynostosis
• Airway related- subglottic stenosis, epiglottitis, croup

75. Complications
• Airway obstruction
• Laryngospasm
• Anaphylaxis
• Awareness, recall, postop behavior changes
• Perioperative cardiac arrest- cardiovascular 40%,respiratory
31%,medication related 20%,eqipment related 4%
• Anesthesia related mortality -0-1.6/10000 cases
• Anesthesia related cardiac arrest- 0.8-4.5%

76. Succinyl choline
• Bradycardia after first dose
• Masseter muscle spasm
• Hyperkalemia -UMNL,LMNL,burns,myopathies,crush injury
• Rhabdomyolysis with duchenne’s MD
• Malignant hyperthermia
• Children below age 6 – caution needed

77. Trouble shoot available on app