2. Introduction
Respiratory system
Cardiovascular system
Renal system
Hepatic system
Haematology
Glucose metabolism
Temperature control
Central nervous system
3. •Pediatric anesthesia involves more than simply adjusting drug doses and
equipment for smaller patients.
• Age groups-
o Neonates (0–1 months)
o Infants (1–12 months)
o Toddlers (12–24 months)
o Young children (2–12 years)
• Risk is generally inversely proportional to age.
INTRODUCTION
4. RESPIRATORY SYSTEM
• Pediatric respiratory system is different than adult in many aspects.
• Neonates preferentially breathe through their nose.
• Small diameter of airways-increases resistance.
5.
6.
7. • Narrowest at cricoid rather
than vocal cords
• Tube may be small enough to
pass through cords but not
cricoid
• Larynx is funnel shaped, so
secretions accumulate in
retropharangeal space
8.
9. • Infants and young children ARE NOT SMALL ADULTS.
• "One size fits all" DOES NOT APPLY.
• Neonates preferentially breathe through their nose.
• The airway is funnel shaped & narrowest at level of cricoid
cartilage.
• Neonates& infants have limited respiratory reserve:
–Horizontal ribs prevent the “buckle-handle” action seen in adult
breathing and limit an increase in Tidal volume.
–Ventilation is primarily diaphragmatic.
–Bulky abdominal organ/ stomach filled with gases from poor bag
mask ventilation--impinge chest content.
10. •The ribs are cartilaginous & perpendicular relative to the vertebral column (Horizontal),
reducing the movement of the rib cage
•The infant chest wall is remarkably compliant & compliance decreases with increasing age
•Subsequently the functional residual capacity (FRC) is relatively low.
•FRC ↓ with apnoea & anaesthesia causing lung collapse.
11. • The presence of fewer, smaller airways produces increased airway
resistance.
• The alveoli are fully mature by late childhood (about 8 years of age).
• The work of breathing is increased and respiratory muscles easily fatigue.
• Neonates and infants have fewer and smaller alveoli, reducing lung
compliance; in contrast their cartilaginous rib cage makes their chest wall
very compliant.
• Relatively higher rate of oxygen consumption.
• Muscle of ventilation are easily subject to fatigue d/t low percentage of
Type I muscle fibres in diaphragm
12. • The transformation to neonatal circulation occurs with the
first few breaths, involes 2 major changes:
• A marked increase in systemic resistance.
• A marked decrease in pulmonary resistance.
• Remnants:Patent Foramen Ovale & Ductus Arteriosus.
• The patent ductus contracts in the first few days of life & will fibrose within
2-4 wks.
• Closure of foramen ovale is pressure dependant & closes in the 1st day of life
but may reopen within the next 5 years.
• Neonatal pulmonary vasculature reacts to the rise in PaO2 & pH & the fall in
PaCO2 at birth.
CARDIOVASCULAR SYSTEM
13.
14. •In neonates Myocardium is less contractile-causing the ventricles to be less
compliant & less ablility to generate tension during contraction.
•HEART RATE DRIVEN CARDIAC OUTPUT.
• Although basal heart rate is greater than in adults , activation of the
parasympathetic nervous system, anesthetic overdose,
or hypoxia can quickly trigger bradycardia and profound reductions in cardiac
output.
•BP is low at birth (approx. 80/50) secondary to a low SVR, due to large
proportion of vessels-rich tissue in children.
•Reaches adult levels at about 16yrs age.
15.
16. RENAL SYSTEM
• Kidney function approaches normal values by 2 years.
• ↓ GFR/ Renal blood flow
•↓ Concentrating capacity
–U/O 1-2ml/kg/hr
• ↓ Na reabsorption
–Tubular function is immature until 8 months, so infants are unable to
excrete a large sodium load.
• ↓HCO3/H exchange.
• Dehydration
17. HEPATIC SYSTEM
• Liver function is initially immature with decreased function of hepatic
enzymes.
•Barbiturates & opiods for example have a longer duration of action d/t
slower metabolism.
18. GLUCOSE METABOLISM
• Neonates have relatively reduced glycogen stores, predisposing them to
hypoglycemia
• Glycogen stores are located in the liver & myocardium
19. HAEMATOLOGY
• At birth, 70-90% of Hb molecules are HbF.
• HB in newbown ~ 18-20g/dL , HCT ~ 0.6.
• O2 dissociation curve shifts to the right as the level of HbA & 2,3-DPG
rise
• Vit K dependant clotting factor (II, VII, IX, X) & PLT fx are deficient in
first few months.
20. TEMPERATURE CONTROL
• Factors which promote greater heat loss to the environment in neonates-
Thin skin.
Low fat content.
Greater surface area relative to weight.
• The more important mechanisms for heat production in neonates are—
Nonshivering thermogenesis by metabolism of brown fat.
Shifting of hepatic oxidative phosphorylation to a more thermogenic pathway.
• Heat loss during Anaesthesia due to--
Conduction.
Convection & evaporation.
21. • Optimal ambient temp to prevent heat loss:
–Premature infant: 34⁰C
–Neonates: 32⁰C
–Adults: 28⁰C
• Effect of low body temp:
Causes respiratory depression
Acidosis
Decreaswd cardiac output
Increases duration of action of drugs
Decrease platelet function
Increases risk of infection
22. • BBB is poorly formed
–Drugs (barbiturates, opioids, antibiotics, bilirubin) cross BBB easily
cause prolong & variable duration of action.
• Cerebral vessels in preterm infant are thin walled & fragile.
–Prone to IVH
–Risk increased with hypoxia, hypercarbia, hypernatraemia, low HCT,
Awake airway manipulation, rapid bicarb administration, & fluctuation
in BP & CBF.
CENTRAL NERVOUS SYSTEM
23. Be aware of:
• Sudden changes in hemodynamics
• Unexpected responses
• Unknown congenital problem
CONCLUSION
Different Anatomy
Different Physiology
Different Pharmacology
Different psychology
↓↓↓↓↓
Different approach & preparation