1. anatomy of paediatric spine 2. cvs 3. cns

1. ANAESTHETIC CONSIDERATIONS
IN PAEDIATRIC PATIENTS
• ANATOMY OF PAEDIATRIC SPINE
• CARDIOVASCULAR SYSTEM
• CNS

2. ANATOMY OF PAEDIATRIC SPINE

3. • At birth dura mater ends at the level of 3rd and 4th Sacral vertebra and the cord (conus
medullaris) at the L3 or L4 level till the end of first year of life.
• Volume of CSF varies considerably according to patient’s age from more than 10ml/kg
in neonates, to 4ml/kg in infants weighing less than 15kg, to 3ml/kg in children, to 1.5-
2.0ml/kg in adolescents and adults.
• Half the CSF volume is located within spinal subarachnoid space in children versus only
25% in adults.
• Delayed ossification of bones fusion of Sacral vertebrae

4. • Neonatal bones including vertebrae are mostly cartilagenous.
• At birth, Single spinal curvature is present.
• Flexures are not fixed, and can be easily counteracted by forced flexion almost
throughout childhood because of spinal flexibility, which is major advantage in
paediatric period.
• Fasciae and perineurovascular sheaths are loosely attached to underlying
structures like nerves, Muscles, tendons, vessels allows extended spread of local
anaesthetics.

5. • Epidural fat is very fluid in infants and young children (till 6-7yrs).
• Delayed myelinization of nerve fibres.
• Exaggerated response of neonates to nociceptive stimulation till first 2 weeks of
life.
• Lack of fusion of Sacral vertebrae
• Changing axis of coccyx and absence of growth of Sacral hiatus.
• Delayed ossification and growth of iliac crests.

6. • Until the age of 1 year, five Sacral vertebrae are easily identifiable and have
appearance of lumbar vertebrae. Each vertebra has five primitive centres of
ossification. Which will knit by 2 to 6years of age due to standing body of child.
• Sacral hiatus is a U-shaped or V- shaped aperture resulting from lack of dorsal
fusion of 5th and often 4th Sacral vertebral arches. Which is limited laterally by two
palpable bony structures- the Sacral cornua, and is covered by the sacrococcygeal
membrane.
• Distance separating the summit of Sacral hiatus and the dural sac ending is
approx. 30mm (SD=10mm) (range, 13.6-54.7 mm) in children 10 months to 18 yrs
of age.

8. • Mean distance from skin to anterior Sacral wall is 21 mm ( extremes, 10-
39mm) between 2 months and 7 years of age.
• The distance from skin to the epidural space is only slightly influenced by the
age and weight of the patient.
• With growth, the axis of sacrum changes. The Sacral hiatus becomes more
difficult to identify and may even close.
• Concomitantly, the epidural fat becomes more densely packed, thus reducing
spread of Local anaesthetics.

10. CARDIOVASCULAR SYSTEM
• In utero, most of the cardiac output is directed from the placenta across the foramen
ovale into the ascending aorta (oxygenated blood), whereas superior vena cava
blood (deoxygenated) is directed to both the pulmonary artery and the ductus
arteriosus.
• This pattern of circulation results in minimal intrauterine pulmonary blood flow.
• At birth, The placenta is removed from the circulation; portal blood pressure falls,
which causes the ductus venosus to close; and blood becomes oxygenated through
the lungs. Exposure of the ductus arteriosus to oxygenated blood induces ductal
closure.

12. • As a result of the combined effects of lung expansion, exposure of blood to
oxygen, and loss of low resistance through placental blood flow, pulmonary
vascular resistance decreases while peripheral vascular resistance rapidly rises.
• The decrease in pulmonary vascular resistance occurs on the first day of life and
continues to decrease gradually during the next several years as the architecture
of the pulmonary vessels changes.
• An increase in pressure on the left side of the heart (caused by the increase in
peripheral vascular resistance) induces mechanical closure of the foramen ovale.

13. • As a result, all three connections between the right and left sides of the
circulation close.
• Although Closure of the ductus arteriosus probably occurs primarily from an
increase in arterial oxygen concentration, successful completion requires arterial
muscular tissue; that such tissue is less prevalent in preterm infants may partly
account for the frequent incidence of patent ductus arteriosus in preterm infants.
• True mechanical closure of the ductus by fibrosis does not occur until 2 to 3
weeks of age. During this critical period, the infant can readily revert from the
adult type of circulation to a fetal type of circulation; this state is called
transitional circulation.

14. • Factors affecting transitional circulation includes- hypoxia, hypercapnia,
hypoglycaemia, hypocalcaemia, overhydration, anesthesia-induced changes in
peripheral or pulmonary vascular tone, prematurity, infection, acidosis,
pulmonary disease resulting in hypercapnia or hypoxemia (aspiration of
meconium), hypothermia, and congenital heart disease.
• When it occurs, pulmonary artery pressure increases to systemic levels, blood is
shunted past the lungs via the patent foramen ovale, and the ductus arteriosus
may reopen and allow blood to shunt at the ductal level.
• A rapid downhill spiral may occur and lead to severe hypoxemia. In this situation,
the hypoxemia may be prolonged, despite adequate pulmonary ventilation with
100% oxygen.

15. • In most cases, simple hyperventilation with resultant reduction in arterial partial
pressure of carbon dioxide (PaCO2) will cause the pulmonary artery pressure to
return to normal.
• Care must be directed to keeping the infant warm, maintaining normal arterial
oxygen and carbon dioxide tensions, and minimizing the effects of anesthetic-
induced myocardial depression for those newborns requiring anesthesia.
• The myocardial structure of the heart, particularly the volume of cellular mass
devoted to contractility, is significantly less developed in neonates than in adults.

16. • This difference, as well as developmental changes in contractile proteins, produce a
leftward displacement of the cardiac function curve and less compliant ventricles.
• As a result of these differences, cardiac output is strongly dependent on heart rate;
bradycardia is poorly tolerated because the infant cannot easily compensate for the
decreased heart rate by increasing stroke volume to maintain normal cardiac output.
• The most frequently encountered arrhythmia in pediatric populations is hypoxia-
induced bradycardia that can lead to asystole, if not appropriately handled.
Ventricular fibrillation is extremely rare in infants and children.

17. • Generally, myocardial function is usually adequate in most infants and children
including those with congenital heart disease.
• Rare exceptions from this rule are Individuals with congenital neuromuscular and
metabolic diseases where the myocardium can be seriously compromised.
• In neonates and infants, cardiac calcium stores are reduced because of the
immaturity of the sarcoplasmic reticulum; consequently, these populations have a
greater dependence on exogenous (blood-ionized) calcium and probably
increased susceptibility to myocardial depression by volatile anesthetics that have
calcium channel blocking activity.

18. CENTRAL NERVOUS SYSTEM
• Major cause of neonatal death is intraventricular hemorrhage due to Short thin
walled And poorly supported capillaries Opening at right angles Into branches of
Internal cerebral vessels, which inturn opens into Veins of galen, again at right
angles.
• Increased surges of arterial pressure caused by- Neonatal asphyxia, hypoxia,
Apnea, large boluses of 8.4% sodium bicarbonate, 10% dextrose, Hypertension
caused by inadequate analgesia or the stimulus of awake Intubations.

19. • In humans, the neural tube is formed between the third and fourth week of
pregnancy and is followed by an active phase of cell proliferation and migration
during the second trimester.
• the most intense phase of brain development takes place between the beginning
of the third trimester of pregnancy and the first few years of postnatal life.
• During this period, also called the brain growth spurt, the nervous system
undergoes important differentiation, including the formation of myriads of
synaptic contacts between neurons.

20. • Neural activity plays a preponderant role in these events especially during critical
periods of development when the nervous system is particularly sensitive to and
relies on external stimuli to drive differentiation of neuronal networks.
• Pharmacologic interference with physiologic activity patterns during this period
may lead to impaired brain development.
• Both premature and term newborns show strong pain behavior that is more
diffuse and untuned when compared to older children and adults.

21. • The first functional and reflex responses to tactile and noxious stimuli are aimed
to protect the individual from tissue damage and can trigger a range of
physiologic responses throughout the whole organism.
• There is evidence that early painful experiences, even if nonconscious, might alter
subsequent central nervous system (CNS) function and that adequate pain relief
can improve outcome.

22. THANK YOU
BY- DR. DAKSHAYANI KONNUR
(INTERN, KOIMS)