Pediatric_Regional_Anesthesia

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Indian Journal of Anaesthesia, June 2008

Paediatric Spinal Anesthesia

Rakhee Goyal1, Kavitha Jinjil2, BB Baj3, Sunil Singh4 , Santosh Kumar5

Summary

Paediatric spinal anesthesia is not only a safe alternative to general anaesthesia but often the anaesthesia

technique of choice in many lower abdominal and lower limb surgeries in children. The misconception regarding its

safety and feasibility is broken and is now found to be even more cost-effective. It is a much preferred technique

especially for the common daycase surgeries generally performed in the paediatric age group. There is no require-

ment of any additional expensive equipment either and this procedure can be easily performed in peripheral centers.

However, greater acceptance and experience is yet desired for this technique to become popular.

Key words Paediatric spinal anaesthesia, Bupivacaine, Infraumbilical surgeries in children

1. Consultant, 2. Consultant, 3. Head of Department, 4. Consultant, 5.P.G.Student, Department of Anesthesiology and Critical

Care, Base hospital, New Delhi, Correspondence to: Rakhee Goyal, Department of Anesthesiology and Critical Care, Base

hospital, New Delhi, Email: [email protected] Accepted for publication on: 18.4.08

Introduction

Regional anaesthesia in children was first studied

by August Bier in 1899. Since then, spinal anaesthesia

was known to be practiced for several years with a

series of cases published as early as in 1909-1910.1-3

In 1900, Bainbridge reported a case of strangulated

hernia repair under spinal anaesthesia in an infant of

three months.4Thereafter, Tyrell Gray, a British sur-

geon published a series of 200 cases of lower abdomi-

nal surgeries in infants and children under spinal anaes-

thesia in 1909-1910. After some years it fell into dis-

use because of the introduction of various muscle re-

laxants and inhalational agents and was almost unused

after World War II.

Thereafter, in 1983, in the American Society of

Anesthesiologists Regional Anesthesia Breakfast Panel,

Abajian et al started the frenzy of modern paediatric

spinal anaesthesia when they reported 78 cases in 81

infants.5The textbook of paediatrics by Leigh and Beltonalso demonstrated that 10% of all anaesthetic proce-

dures practiced in children at the Vancouver General

Hospital were spinal techniques, including pulmonary

lobectomies and pneumonectomies.5However, paedi-

atric spinal anaesthesia never achieved its popularity

because of continuous discoveries of newer and better

volatile agents and muscle relaxants for general anaes-

thesia.

In the last decade, it started being advocated again

by many centers due to increasing knowledge on phar-

macology, safety information and availability of spe-

cialized equipment for regional anaesthetic techniques

and monitoring in children. In the coming times, paedi-

atric spinal anaesthesia will not only be used in cases

where general anaesthesia is risky or contraindicated

but also be the preferred choice in most lower abdominal

and lower extremity surgeries in children.

Anatomical and physiological differences

in children

There are certain features of paediatric anatomy

and physiology which are different from the adult and

thus make the central neuraxial blockade a good alter-

native anaesthetic technique. The spinal cord ends at

L3 level at birth and reaches L-1 by 6-12 months. Thedural sac is at the S4 level at birth and reaches S2 by

the end of the first year. The line joining the two supe-

rior iliac crests (inter-cristal line) crosses at L5-S1 in-

terspace at birth, L5 vertebra in young children and

L3/4 interspace in adults. It is for this reason that the

lumbar puncture be done at a level below which the

Indian Journal of Anaesthesia 2008; 52 (3):264-270 Special Article


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cord ends, safest being at or below the inter cristal line.

The bones of the sacrum are not fused posteriorly in

children enabling an access to the subarachnoid spaceeven at this level.

Another feature which is unique in infants is that

there is only one anterior concave curvature of the ver-

tebral column at birth. The cervical lordosis begins in

the first 3 months of life with the childs ability to hold

the head upright. The lumbar lordosis starts as the child

begins to walk at the age of 6-9 months. Therefore, the

spread of isobaric local anaesthetic is different in in-

fants particularly as compared to adults.

The subarachnoid space is incompletely divided

by the denticulate ligament laterally, and the subarach-

noid septum medially. The volume of cerebrospinal fluid

CSF is 4 ml.kg-1which is double the adult volume.

Moreover, in infants half of this volume is in the spinal

space whereas adults have only one-fourth. This sig-

nificantly affects the pharmocokinetics of intrathecal

drugs. The spinal fluid hydrostatic pressure of 30-40mm

H2O in horizontal position is also much less than that in

adults.6

The neck can be in extension for lateral position-

ing while performing a lumbar puncture as cervical flex-

ion is of no benefit in children and in fact, may obstruct

the airway during the procedure. It can also be per-

formed in sitting position with the head extended.

The physiological impact of sympathectomy is

minimal or none in smaller age groups. The fall in blood

pressure and a drop in the heart rate are practically not

seen in children less than five years. Therefore there is

no role of preloading with fluids before a subarachnoid

block. This may be due to the immature sympathetic

nervous system in children younger than fiveeight years

or a result of the relatively small intravascular volume in

the lower extremities and splanchnic system limiting

venous pooling and relatively vasodilated peripheral

blood vessels.7Infants respond to high thoracic spinal

anaesthesia by reflex withdrawal of vagal parasympa-

thetic tone to the heart. It is one of the reasons why

spinal anaesthesia has been the technique of choice in

critically ill and moribund neonates who present for

surgery in grave haemodynamic instability.

Pharmacology

The most important concern with the use of in-

trathecal local anaesthetics in infants and young chil-

dren is the risk of toxicity. This age group is particularly

prone to direct toxicity to the spinal cord when admin-

istered in large doses. Neonates with immature hepatic

metabolism and decreased plasma proteins like albu-

min and 1 acid glycoprotein have higher serum lev-

els of unbound amide local anaesthetics, which are nor-

mally highly protein bound (90%). A relatively highercardiac output and regional blood flow in infants also

increases the drug uptake from neuraxial spaces and

can predispose them to local anaesthetic toxicity be-

sides decreasing the duration of action. Infants may have

decreased levels of plasma pseudocholinesterase which

may augment local anaesthetic toxicity especially with

the ester group.8 Various anaesthetics have been used

for paediatric spinal anaesthesia but bupivacaine and

ropivacaine remain the drugs of choice.

Indications

Infraumbilical extraperitoneal surgeries like ing-

uinal hernia, circumcision, hypospadias, orchidopexy,

cystoscopy, colostomy for imperforate anus, rectal bi-

opsy and other perineal surgeries; lower extremity or-

thopaedic and reconstructive surgeries.

Preterm and former preterm infants less than 60

weeks post-conceptual age/less than 3 Kg/hematocrit


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Besides these common indications, there are re-

ports of successful spinal anaesthesia in complex sur-

geries like meningomyelocele, gastroschisis repair, openheart surgery 10etc in addition to light general anaes-

thesia.

Contraindications

Refusal of the parents, progressive neurological

disease, uncontrolled convulsions, infection of the skin

or subcutaneous tissue locally at puncture site, coagu-

lation defects, true allergy to local anaesthetics and se-

vere hypovolemia are some of the contraindications to

spinal anaesthesia in children.

Consent and risk-benefit aspect

Consent from the parents is an important issue

before planning a central neuraxial blockade for chil-

dren. The consent should be informed and written, and

the various aspects of regional technique alongwith the

risks involved must be explained in detail. There is also

an obvious need to assess the risk involved in the pro-

cedure on an individual case basis versus the benefits

expected depending on the nature and duration of sur-gery, general condition of the patient and the availabil-

ity of institutional care intra and postoperatively.

NPO and premedication protocols

The standard preoperative fasting guidelines are

required to be followed before elective spinal anaes-

thesia. 2-3 hrs fasting for clear fluids, 4 hrs for other

fluids and 6 hrs for solids is usually followed in most

centers.

Adequate premedication is the key to a smooth

regional procedure in children. Various drugs via dif-

ferent routes may be used to achieve a well sedated

child who allows venous puncture, placement of moni-

tors and even a lumbar puncture. Oral combination of

ketamine 4-6mg.kg-1, midazolam 0.4mg.kg-1and atro-

pine 0.03mg.kg-1is quite effective and safe in most

cases.6Other routes of premedication like rectal, sub-

lingual, nasal or intramuscular are also practiced. What-

ever may be the drug and the route of administration, it

is important that it is customized for each type of pa-

tient and surgery involved and also safe during the en-tire perioperative period.11

Procedure, needles used, drug dose

The basic procedure of performing a subarach-

noid block in children is similar to adults and full asep-

tic precautions are a must. It is important to access the

CSF through appropriate space as per the age of the

child as already discussed in order to avoid trauma to

the spinal cord. Care should be taken as the child may

be asleep or inadequately sedated. However, additionalanalgesia and sedation is generally required during lum-

bar puncture. It may be supplemented with low dose

ketamine or a short acting drug like thiopental/propofol

intravenously or inhalational anaesthetics like oxygen-

nitrous oxide, sevoflurane or halothane during the pro-

cedure. Anticholinergic drugs may be added to decrease

any undesired secretions. Application of 5% EMLA

(eutectic mixture of local anaesthetics-lidocaine and

prilocaine) with an occlusive dressing on the appropri-

ate and best palpated interspace about an hour beforesurgery facilitates painless lumbar puncture without any

additional parenteral sedation. EMLA should be used

with caution in infants less than three months and those

receiving any methemoglobin inducing drugs like sul-

fonamides, phenytoin, phenobarbital, acetaminophen.12

Intraoperatively, sedation can be augmented with

midazolam upto 0.1mg.kg-1. Flavoured pacifiers for

young and music or books for older children may be

used in case the child is awake and cooperative.

The needles available for paediatric use range from24-29 G, either short bevelled Quincke or Sprotte and

Whitacre with or without introducer with a length shorter

than that in adults. If specialised needles are unavail-

able or their cost is prohibitive, even hypodermic needle

or the metal stillete of a small gauge intravenous can-

nula can be used without much difficulty. Correct place-

ment of the needle is ascertained by free flow of CSF.

Some of the needles also have a magnifier hub for fast

recognition of flashback of CSF. The child may be kept


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in the dependent side for a few minutes for lateralisation

of the block. A successful block usually takes about 2-

5 mins and care should be taken that the leg is not liftedjust after the block for placement of diathermy pads

which often results in undesired cephalad spread of the

block.

The extent of the sensory block can be checked

by pin-prick or skin pinch and that of the motor block

by Bromage scale.13This may however be difficult to

check in a deeply sedated child and can only be done

in the postanesthesia care unit (PACU) to check the

block regression. However, it can be clinically ascer-

tained by lack of leg movement and diaphragmaticbreathing. Children very often fall asleep with the de-

afferentation following the block.

Intraoperative fluids only include deficit and main-

tenance amounts and preload need not be given as in

adults. The hypotensive cardiovascular response to

sympathectomy is minimal or none in children. How-

ever, standard monitoring is mandatory and oxygen by

face mask is recommended in all cases.

All patients should be monitored in the PACU for

vital signs, two-segment block regression, pain and any

other side effect. Children should only be discharged

when they are awake and able to walk unaided, the

vital signs are stable for at least 1 h, there is no pain,

nausea/retching or vomiting, and are ableto tolerate

clear fluids.

Intrathecal drugs

Among the various drugs approved by FDA for

paediatric intrathecal use, 0.5% bupivacaine and

ropivacaine are common and popular. The doses used

are institutional though the standard protocol that I have

been practicing is 0.5% bupivacaine 0.1ml.kg-1or

0.5mg.kg-1for infants weighing 0-5 Kg; 0.08ml.Kg-1

or 0.4mg.kg-1for 5-15Kg body weight and 0.06ml.kg-

1or 0.3mg.kg-1for >15 Kg weight.6

Levobupivacaine has very similar PH) arma-

cokinetic propertiesto those of racemic bupiva-caine,

but the potential for toxicitywith levobupivacaine is less.

Kokki et al performed a study on 40 children, aged 1

14 yr, undergoing

elective lower abdominal or lowerlimb surgery levobupivacaine 5 mg.mL-1at a mean dose

of 0.3 mg.kg1bodyweight, and found equivalent clini-

cal efficacy in spinal anaesthesia in childrento that of

racemic bupivacaine.14, 15

Ropivacaine 5mg.ml-1has also been used in some

studies and found to be effective and safe in isobaric

form. In a study of 93 children 1-17 years of age, Kokki

H et al used 0.5mg.kg-1(upto 20mg) in lateral decubi-

tus position and achieved good block performance.16

Baricity is one of the most significant factors to

affect the distribution of the local anaesthetic and hence

success and spread of the blockade. The effect of dif-

fering degrees of hyperbaricity was evaluated by sev-

eral workers in paediatric age group. It is not known

whether hyperbaric local anaesthetic is better than iso-

baric in children in contrast to adults where it is proven

to be more reliable, safe and effective.17Isobaric

bupivacaine has also been used for spinal anaesthesia

in children and compared with its hyperbaric form.Kokki H 18compared bupivacaine 5 mg.ml-1, isobaric

in saline 0.9% and hyperbaric in 8% glucose, for spinal

anaesthesia in 100 children, aged 2-115 months for

paediatric day case surgery. The success rate of the

block was greater with hyperbaric bupivacaine (96%)

compared with isobaric bupivacaine (82%). Intense

motor block was associated with adequate sensory

block. Spread and duration of sensory block showed

a similar wide scatter in both groups. Cardiovascular

stability was good in both groups. The study gave an

impression of a delayed onset time of spinal block, as

most of the nine children who required either fentanyl

or a sedative for a mild reaction to skin incision had

complete block when transferred to the recovery room

after operation.

However, in an article published two years later

the same authors, Kokki H et al demonstrated that

bupivacaine in 0.9% glucose and in 8% glucose solu-

tions are equally suitable for spinal anaesthesia in small

Rakhee Goyal et al. Paediatric spinal anaesthesia


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children. Similar success rate, spread and duration of

the sensory and motor block are achieved with both

baricities of bupivacaine.

19

Various studies have been done with child in lat-

eral or sitting position for a subarachnoid block. In a

study on 30 preterm infants for inguinal herniotomy, Vila

et al found spinal anaesthesia to be equally effective in

both lateral and sitting position.20

Duration is an important and a limiting factor for

paediatric spinal anaesthesia especially in infants and

younger children. Spinal anaesthesia alone for this rea-

son is therefore generally restricted to one hour dura-tion surgeries only. The duration is longer with larger

doses in infants and varies directly with the age of the

child. It has been seen that the duration of long acting

local anaesthetics like bupivacaine is only about 45 min

in neonates and 75-90 min in children upto five years.

There is no difference in duration by adding epineph-

rine to bupivacaine.

Additives

Since the duration of spinal anaesthesia does notcover most of the postoperative period, it is essential

to add intravenous or rectal acetaminophen or

ketoprofen routinely to all patients. Profound postop-

erative analgesia can be achieved by adding a low dose

local anaesthetic with or without an opioid (fentanyl),

clonidine 1-2g.kg-1or any other additive in caudal

space at the time of performing the subarachnoid block.

A caudal catheter can also be placed and local anaes-

thetic plus opioid added for prolonged analgesia post-

operatively.

Complications

The complications related to spinal anaesthesia

are usually either due to the needle used to perform the

procedure (backache, headache, nerve or vascular in-

jury and infection) or the drugs injected (high or total

spinal, drug toxicity). However, little data is available

regarding the incidence as compared to adults.

Post dural puncture headache (PDPH) is rare in

paediatric patients and some authors have even chal-

lenged its existence. In his study on 200 children using

two different sizes spinal needles of 25 G and 29 GQuinke, Kokki et al 21found that 10 had PDPH with

no difference regarding the type of needle used. The

failure rate of attempted spinal anaesthesia was 4% and

even when the subarachnoid space was reached and

the local anaesthetic injected, the overall success rate

of the technique was only 91%.

Transient neurological symptom (TNS) has been

reported by some authors following spinal anaesthesia

due to direct toxicity of large doses of local anaesthetics.

In his study on 95 patients using 0.5% isobaricropivacaine, Kokki et al16reported mild to moderate

TNS in four children which was transient and was not

followed by any permanent neurological sequelae. In

another study by the same author similar results were

found with 0.5% bupivacaine.17

A one year study of 24,409 regional blocks in

children by the French-Language Society of Pediatric

Anesthesiologists,22the largest known study on com-

plications, revealed a complication rate of 1.5 per 1000

in the 60% of children receiving central neuraxial blocks.

However, most of these cases were those of caudal

and some of epidural technique.

Advantages

Spinal anaesthesia produces a reliable, profound

and uniformly distributedsensory block with rapid on-

set and good muscle relaxation, andit results in more

complete control of cardiovascular and stressresponses

than epidural or opioid anaesthesia.23

It is ideal for day-case surgeries and is safe and cost-effective. There is

no additional requirement of any special drug or equip-

ment for the procedure. Because ofthese benefits, spi-

nal anaesthesia has gained acceptance forchildren un-

dergoing surgery in the lower part of the body.24

Comparison with general anaesthesia

General anaesthesia may be associated with sev-

eral life-threatening complications especially in preterm,


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former preterm, those with co-morbidities like sepsis,

necrotising enterocolitis, anaemia (hematocrit


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On Line Availability of IJAOn Line Availability of IJAOn Line Availability of IJAOn Line Availability of IJAOn Line Availability of IJA

FULL TEXT

On website http://indmed.nic.in OR http://medind.nic.in

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