Paediatric spinal anaesthesiaclinical pearls

Dr. S. Parthasarathy MD., DA., DNB, MD (Acu), Dip. Diab. DCA,Dip. Software statistics • PhD (physio)• Mahatma Gandhi medical

college and research institute – Puducherry – India

History

• Spinal anesthesia was probably the earliest form of regional anesthesia that was considered a useful practice for children

• ( Bainbridge, 1901 ; Tyrell-Gray, 1909 ).

• Popularized in 1990 s

Why it came to lime light ??

• Premature infants – possible hernia

• Muscular and neuromuscular disease for abd. And lower limb surgery.

Other indications • The safety and success of spinal • such as pyloromyotomy, gastrostomy

placement,• myelomeningocele repair,• cardiac surgery, and genitourinary

procedures.• Moreover, spinal anesthesia has been

successfully used in high-risk infants and• for cardiac catheterization,

To consider spinal in ??

• facial dysmorphia • difficult intubation, • muscular dystrophy, • family history of malignant hyperthermia• or a full stomach with aspiration risk

Contraindications • Coagulation abnormalities• Systemic sepsis or local infection at the

puncture point• Uncorrected hypovolaemia• Parental refusal or an uncooperative child• Neurological abnormalities such as spina

bifida,• increased intracranial pressure• Procedures lasting more than 90 minutes

• Are there any differences ??

Where does spinal cord end ?

• The conus medullaris lies at a lower level in infants;

• therefore the L4-5 or L5-sacral interspace should be chosen for the dural puncture

Difference

Intercristal line ??

• The intercristal line crosses the midline at the S1 interspace in neonates, and at the L5 interspace in older children

differences

• The approach to the subarachnoid space requires a straighter trajectory of the needle than in older children.

• The distance to the subarachnoid space is small, • cerebral spinal fluid (CSF) flow may be slow,• ligamentum flavum is thin

Difference

• 4 mL/kg (2 mL/kg in adults) with 50% being in

the spinal canal compared with 25% in adults

• Duration – short

• Even bupivacaine 90 minutes

Technique

• Positioning – • Flex back but extend neck • Sedate ?? • Enough local , EMLA 60 minutes before • Ready with airways

Technique • Standard monitors, IV access • Distance from skin to subarachnoid space (cm)

= 0. 03 x height (cm)• 1 inch 22 g spinal needle• depth of 1 to 1.5 cm• distance in millimeters = (age in years• x2) + 10.• Aspirate and slowly inject • Don’t lift legs to place cautery

Sitting spinal – neonate

Technique

• The ligamentum flavum is very soft in children

and a distinctive “pop” may not be perceived

when the dura is penetrated.

• Be gentle and slow

Straight – 1 ml syringe

Characters of nerve fibres

• Small nerve fibres

• Nonmyelinated

• Small distances between nodes of ranvier

• Lumbar lordosis - Absent but in two years it

may be present

Differences

• fibrous sheaths around nerves are not well developed and myelination is not complete until about 2 years of age.

• This makes immature nerves more sensitive to local anaesthetics and less concentrated solutions than are used in adults usually result in a dense block.

• In term babies the length of the spinal cord is about 20 cm (in adults 65–70 cm).

• This means that the length to weight ratio is four or five times higher in newborns than in adults.

• so -- Dose differences

Assessing the block is difficult.

• The response to cold spray can be useful,

• observation of paradoxical respiratory muscle

movement

• loss of response to a low amperage tetanic

stimulus.

Level ??

• Pacifier nipple • Spread of the block is less predictable• High level means – • no BP fall but apnea !!

• Monitor 24 hours

Bupi and tetra

• Heavy bupivacaine is recommended in a dose of 0.3-1 mg/kg = 0.07-0.2 mL/kg of 0.5% solution.

• 2 kg infant – hernia – 0.2 ml ?? • 6 kg infant – circumcision – 0.5 ml ?? • 14 kg 2 years – orchipexy – 1.5 ml • 1% tetracaine, a dose of 0.5 mg/kg• Empty the needle

Other drugs

• Doses ranging between 0.75 and 1.25 mg/kg of isobaric solution of levobupivacaine

• addition of 100 μg clonidine to 20 ml bupi and inject the necessary dose

• Or • Add 1 μg / kg • Other drug dosage schedules

Doses in mg / kg Age Bupi Tetra Ropi

Infants 0.5 – 1 0.5 – 1 0.5 – 1

1 - 7 0.3 – 0.5 0.3 0.5

> 7 0.2 -0.3 0.2 0.4

Complications

• Less than 6 months of age, immature hepatic metabolism of amide drugs

• Failure rate – 10 – 20 % • Brady – ok but hypo - ??• PDPH – restlessness . Hearing loss !! • Potential traumatic puncture • But – overall – very rare

Causes of haemodynamic stability

• immaturity of the sympathetic nervous system

• smaller blood volume that is present in the lower extremities

Summary

Dose and drugs Position DexterityComplications Spinal – safe In safe hands

Thank you all