Neuraxial block

MODERATORS
DR. SHIKHA MEHROTRA (PROFESSOR)
DR. SANDEEP RATHORE(ASST. PROFESSOR)
DEPARTMENT OF ANESTHESIA
GMC BHOPAL
PRESENTED BY
DR.DIVYA GAUTAM (RESIDENT)

Introduction
 The spinal,epidural and caudal blocks are collectively known as
NEURAXIAL BLOCK
 Each of these blocks can be performed as a single injection or
with a catheter to allow intermittent boluses or continuous
infusion.
 These blocks result in sympathetic block, sensory analgesia and
motor block depending upon the dose, concentration and
volume of local anaesthetic .

HISTORYOF NEURAXIAL BLOCKS
SPINALANESTHESIA
(A)FIRST SPINAL ANESTHESIA WAS GIVEN BY J.LEONARD
CORNING IN 1885 IN A DOG.
(B)FIRST PLANNED SPINAL ANESTHESIA IN MAN WAS
PERFORMED BY AUGUST BIER ON 16TH AUGUST 1898 IN
KIEL(GERMANY)
(C) FIRST SPINAL WITH BUPIVACAINE BY EMBLEM IN 1966
(D)LUMBAR PUNCTURE STANDARDIZED AS A SIMPLE
CLINICAL PROCEDURE BY QUINCKE IN 1891(GERMANY)
(E)PITKIN POPULARIZED THE METHOD OF INTRODUCING
ANALGESIC AGENTS INTRATHECALLY.

EPIDURALANESTHESIA
 INTRODUCED BY CORNING AND USED IN DOGS BY
CATHELIN AND SICARD IN 1901 AND IN MAN BY
KAPPIS AND BY BLEECK AND STRAUS.
 APPLIED IN CLINICAL SURGERY BY PAGES IN 1921
AND DOGLIOTTI & ABUREL IN 1931.
 CURBELO OF CUBA WAS THE FIRST WORKER TO
INSERT A CATHETER INTO THE EXTRADURAL SPACE
IN 1949
 ROBERT ANDREW HINGSON (1913–1996)DEVELOPED
TECHNIQUE OF CONTINOUS CAUDAL ANESTHESIA

ADVANTAGES Of REGIONAL ANESTHESIA OVER
GENERAL ANESTHESIA
 It is cheaper, lessen the risk of pulmonary aspiration,
limits stress response.
 Alternative to GA for certain poor risk patients esp.:
Difficult airway
Respiratory disease
 Respiratory complication like bronchospasm
laryngospasm, postoperative atelectasis and hypoxia are
obviated.
 Systemic side effect of general anesthesia drugs are not
seen.

 All serious consequences of intubation like
cardiovascular response and failed intubations are obviated.
 Disturbance of body chemistry are minimal
 Bleeding is less(because of low mean arterial pressure)
 Decreased incidence of thromboembolism due to
increased vascularity of lower limbs.
 Gives post operative analgesia.
 Patient is awake.

DISADVANTAGES
 TIME CONSUMING.
 MOTOR PARALYSIS PERSISTS IN POST OPERATIVE
PERIOD.
 SOME PATIENTS PREFER TO BE ASLEEP.
 HYPO TENSION AND PDPH.
 TECHNICAL DIFFICUTLY AND COMPLICATIONS

SURFACE ANATOMY
Anatomic Landmarks to Identify Vertebral
Levels
Anatomic
Landmark
Features
C7 Vertebral prominence, the most
prominent process in the neck
T7 Inferior angle of the scapula
L4 Line connecting iliac crests
S2 Line connecting the posterior
superior iliac spines
Sacral
hiatus
Groove or depression just above or
between the gluteal clefts above
the coccyx

DERMATOMES Dermatomal
Level
Surface
Landmark
C8 Little finger
T1,T2 Inner aspect of
the arm
T4 Nipple line, root
of scapula
T7 Inferior border of
scapula ,Tip of
xiphoid
T10 Umbilicus
L1 to L2 Inguinal ligament
L2 to L3 Anterior thigh
S1 Heel of foot

SEGMENTAL LEVELS OF
SPINAL REFLEX
 EPIGASTRIC REFLEX T7-T8
 ABDOMINAL REFLEX T9-T12
 CREMASTRIC REFLEX L1-L2
 PLANTER REFLEX S1-S2
 KNEE JERK REFLEX L2-L4
 ANKLE JERK REFLEX S1-S2
 ANAL SPHINCTER S4-S5

Level of block required in different
surgeries

Spinal Cord
Extends from foramen magnum to
•Adult : lower border of L1
•Infants/children : L3
• It is about 45 cm long
• Duramater, Subarachnoid space &
subdural space: S2 in adults(S3 in
children)
• Spinal cord gives 31 pairs of spinal nerve
• An extension of piamater , the FILUM
TERMINALE penetrate the dura and
attach the terminal end of spinal cord
[conus medullaris]to the periosteum of
the coccyx
• Sympathetic N.S arises from
intermediolateral grey mater of T1 to L2
cord segments.

BLOOD SUPPLY
 Blood is supplied to the spinal cord from one anterior spinal artery
(originating from the vertebral artery), two posterior spinal arteries
(originating from the Posterior inferior cerebellar artery), and the
segmental spinal arteries (originating from the intercostal and lumbar
arteries).
 One of the major branches is the artery of Adamkiewicz, variably
entering between T7 and L4 on the left, which supplies the lower
thoracic and upper lumbar regions.
 The anterior two thirds of the spinal cord is supplied by the anterior
arterial branches and the posterior one third by the posterior branches.

Membranes that surround the spinal cord
(MENINGES)
Pia mater-
 Innermost, highly vascular layer covers the spinal cord and brain
 Contains numerous fenestrations along lumbar cord and nerve
roots
Arachnoid mater-
 non vascular and attached to the dura matter.
 Principle barrier to the migration of medication in and out of the
CSF due to its selective permeability and trabecular web like
network.
Dura mater-
 Thickest layer,composed of collagen fibres in lamellar pattern
 extension of the cranial dura mater extend from foramen magnum
to S2(ending at the filum terminale) and extends laterally to fuse
with epineurium near intervertebral foramina.

VERTEBRAE ANATOMY
33 vertebrae
7 cervical
12 thoracic
5 lumbar
5 fused sacral
4 fused coccygeal
 All vertebrae have same structural components but with
varying shapes and sizes at different levels
 The vertebrae surround and protect the vertebral canal which
contains the spinal cord, csf, spinal nerves and epidural space.

 Each vertebra has a body anteriorly,two pedicles that project
posteriorly from the body, and laminae that connect the two
pedicles.
 The transverse processes arise laterally from junction of pedicle
and lamina
 The spinous process projects posteriorly from union of the
bilateral laminae.
 The para spinous muscles and ligaments attach to these bony
projections
 -Terminal End: Conus Medullaris
 – Filum Terminale: Anchors in sacral region
 – Cauda Equina: Neural end of lower dural sac

LIGAMENT THAT SUPPORT VERTEBRAL COLUMN

Cerebrospinal Fluid
 Clear aqueous fluid that fills the subarachnoid space
 Total volume in adult is 100-150ml (99%water)
 Volume found in subarchnoid space is 125 ml
 Continually produced at a rate of 450-500 ml per 24 hour
period replacing itself 3-4 times
 Produced and absorbed in the parenchymal capillaries of
brain and spinal cord and via lymphatics
 Reabsorbed into the by arachnoid villi and granulations
 Opening pressure is high in sitting position than lying
down( N=15cm H2O)
 Specific gravity is between 1.003-1.009

Important Facts
 Cardiac accelerator fibre: T1-T4(Bradycardia & ↓
contractility)
 Vasomotor fibre : T5-L1( Determine vasomotor
tone)(vasodilation on blockade)
 Sympathetic outflow arise from T5-L1(Block ↑vagal
tone, small contracted gut with active peristalsis)
 Most dependent part in supine position is T4-T8 (imp.
for hyperbaric solution

SPINAL ANAESTHESIA
(SUBARACHNOID BLOCK)
Spinal anesthesia involves the use of small amounts of local
anesthetic injected into the subarachnoid space to produce
a reversible loss of sensation and motor function.
INDICATIONS-
 Orthopaedics surgery of lower limb and pelvis
 General surgery :All pelvic and perineal surgeries, hernia, hydrocele
,testicular surgeries ,appendix
 Gynecology and obstetrics: All uterine surgeries like hysterectomy
,myomectomy, cervical surgeries, caesarean section
tubectomy,tuboplasty ,ovarian surgeries
 Urology: Bladder and uretric stone ,prostate surgery
Surgery of upper abdomen like pyelolithotomy and even cholecystectomy
can be perfomed in spinal anesthesia by giving head (Trendelenburg )tilt

SITE
• Adult : L3-L4 or L4-L5 ( or even
L2-L3)
• Infant : L4-L5
• A line drawn b/w the highest Point
of iliac crests (Tuffier’s line) usually
cross either body of L4 or the L4-L5
interspace
POSITION
 Sitting
 lateral
Prone(anorectal procedure,jack
knife position)

Various approaches for subarchnoid
block
 Midline approach
 Paramedian approach
Midline Approach Paramedian
approach
Skin Skin
Subcutaneous fat Subcutaneous fat
Supraspinous ligament Paraspinal muscles
Interspinous ligament
Ligamentum flavum Ligmentum flavum
Dura mater Dura mater
Subdural space Subdural space
Arachnoid mater Arachnoid mater
Subarachnoid space Subarachnoid space

Approaches
Spinal puncture is given by either midline or Para median approach.
Midline approach
o Under full asepsis and sterile gloves worn the painted area is draped
and the spine is palpated
oSelect widest interspace preferably L3-L4.
oRaise a skin wheal with 2% lidocaine infiltration
oInsert spinal needle in the midline with bevel parallel to the
longitudinal axis of the spine.
oAdvance needle and asses the feel of dura puncture.
oRemove stylet to observe the free flow of CSF.
oAttach the 5ml syringe containing drug to be injected in subarachnoid
space, by stabilizing the spinal needle with non-dominant hand holding
hub of needle between the thumb and fingers
oInject the prepared solution at the rate of 0.2ml/sec.

 Para median approach
o Identify the caudal edge of cephalad spinous process.
o Raise a skin wheal 1cm lateral and 1cm caudal to this point
o Needle is inserted at an angle of 15 degree to the saggital
plane in a cephalomedial direction.
Lumbosacral approach (TAYLOR’S APPROACH)
- Modification of paramedian for epidural block
• A needle is inserted
1 cm medially and 1 cm inferior to
prominence of posterior
superior iliac spine at L5-S1 level
• Needle is directed upward
medially and forwards at 45-55 degree
• Useful in patients with degenerative spine
diseases, trauma patients who cannot maintain
Sitting position

STRUCTURES ENCOUNTERED DURING
SPINAL ANSTHESIA
1.Skin
2.Subcutanious tissue
3.Supraspinous ligaments:
Connecting the tips of spinous
process
4.Interspinous ligaments: joins
the spinous processes together
5.Ligamentum flavum: Running
from lamina to lamina. Composed of
yellow elastin fibres so called yellow
ligament
6.Dura
7.Arachonid

SITE OF ACTION-
Target binding sites are the superficial and deep portions of spinal cord spinal
nerve roots in subarachnoid and epidural space and dorsal root ganglia.
 Speed of neural blockade depends on size, surface area, degree of
myelination of nerve fibres.(S1 and L5 posterior roots are largest and most
resistant to blockade)
 Differential blockade
„ Autonomic>sensory>motor
(For eg the level of anesthesia to cold sensation most cephalad and is one to
two segments higher than the level of pinprick anesthesia which in turn is one
to two segments higher than the level of touch anesthesia)
 „Sympathetic blockade may be two dermatomes higher than sensory block
(pain, light touch)
 Drug penetration and uptake is directly propotional to drug mass,CSF drug
concentration, contact surface area, lipid content and local tissue vascular
supply and inversely related to nerve root size
 Concentration of drug is highest at site of injection.
 Time for block regression is inversely propotional to to the CSF volume
Mechanism of Action

PHYSIOLOGICAL EFFECTS OF SPINAL
ANAESTHESIA
1.CARDIOVASCULAR SYSTEM
Combined α+β blocking effect on heart
Venodilatation and fall in venous return lead to low cardiac output and
hypotension during onset(Bain-bridge reflex)
Decreased stroke volume and heart rate due to blockade of peripheral
(T1-L2) and cardiac (T1-T4) fibres and decreased adrenal medullary secretion
Cardiac output shows a biphasic response i.e. early transient increase
followed by eventual decrease. (Initial increase is due to greater decline in
SVR than the venous return) especially in old age with preexisting
hypertension
In old age with cardiac disease SVR tend to fall by 25% whereas CO falls
by only 10-15%

Block of cardio acclerator sympathetic fibers from T1-T4 leads to
subsequent bradycardia
Extensive peripheral sympathectomy(T5-L2) also leads to
bradycardia and pooling in lower extremities
Hypotension triggers compensatory baroreceptor response leading
to vasoconstriction and tachycardia above block level, reduction in
venous return/RA filling which decreases signal output of intrinsic
chronotropic receptors of RA leading to increase in parasympathetic
tone.
BEZOLD JARISCH REFLEX- Bradycardia and subsequent
cardiac arrest due to profound hypotension via activation of 5HT3
mediated receptors of vagus and the ventricular myocardium.

2.GASTROINTESTINAL FUNCTIONS
 Nausea and vomiting due to GI hyper peristalsis due to
unopposed vagal activity. Contracted bowel and relaxed
sphincters due to sympathetic blockade.
 Spleen enlarges 2-3 times in high blocks when its
sympathetic efferent fibers (splanchnic nerves) are blocked.
 Bladder and urogenital dysfunction
 Colonic blood supply and oxygen availability is increased.

3.RESPIRATORY SYSTEM
 High spinal may cause paralysis of intercostal muscles,
diaphragm and accessory respiratory muscles.
 Cautiously given in patients with limited respiratory
reserve
 Tidal volume remain unchanged.
 Vital capacity decreases minimally d/t loss of abdominal
muscle contribution in forced expiration
 Apnea due to hypotension which causes medullary
ischemia in high/total spinal cases
4. THERMOREGULATION
 Vasodilatation causes heat loss which is compensated by
vasoconstriction and shivering above the level of block.

5.ENDOCRINE
-Stress response is inhibited
-response to insulin is augmented
-usual increase in ADH during surgery is inhibited
Spinal anesthesia in pregnacy
Decreased dose requirement due to
 Mechanical factor : compression of IVC causes shunting of
blood to the venous plexus in the vertebral canal leading to
decreased vertebral canal space and CSF volume
Hormonal factor – higher progesterone levels

SPINAL NEEDLES
 Standard spinal needle consist of
three parts:-
-Hub
-Cannula
-Removable stylet
 Sizes available- 16 to 30 gauge.
 Length of spinal needle – 90mm
 Needles are either
-Sharp or blunt at tip.
-Pencil point needle.
-Sharp or round bevel edge.
Dura cutting needle: QUINCKE-
BABCOCK and GREENE
Dura seprating: WHITCRE,SPORTE
AND PITKIN

Spinal needle
Gauge(mm)
 16(1.6mm)
 18(1.2mm)
 19(1.1mm)
 20(0.9mm)
 21(0.8mm)
 22(0.7mm)
 23(0.6mm)
 25(0.5mm)
 26(0.5mm)
 27(0.40mm)
Colour code
 White
 Pink
 Cream
 Yellow
 Deep green
 Black
 Deep blue
 Orange
 Brown
 Grey

DRUG
 Lidocaine is 5% and hyperbaric by addition of
7.5%dextrose
 Rapid onset of action and low toxicity
 Bupivacaine is 0.5%and made hyperbaric by addition of
8%dextrose
Dose
 <5kg—0.5mg/kg body wt
 5-15kg—0.4mg/kg body wt
 >15kg—0.3mg/kg body wt
 Ropivacaine (0.5% in dextrose)
 Levobupivacaine

MECHANISM OF ACTION
 Local anaesthetic solution injected into the subarachnoid space
blocks conduction of impulses along all nerves with which it comes
in contact, DIFFUSION is the primary mechanism of local drug
distribution
 Stimulation of the motor nerves causes muscles to contract and
when they are blocked, muscle paralysis results.
 Interacts with the receptor situated within the voltage sensitive
sodium channel and raises the threshold of channel opening
decreases the entry of sodium ions during upstroke of action
potential
 Local depolarization fails to reach the threshold potential and
conduction block ensues
• Generally, autonomic and sensory fibres are blocked before motor
fibres.

Baricity of Local Anesthetics
Density of a solution in relation to density of CSF
Isobaric – Stays where you put it
LA has the same density or specific gravity as CSF (1.003-
1.008) – Normal Saline
Hypobaric – “Floats” up – Lighter than CSF
LA has a density or specific gravity that is less than CSF
(<1.003) – Sterile Water
Hyperbaric – Settles to Dependent aspect of the
subarachnoid space – Heavier than CSF
LA has a density or specific gravity that is greater than CSF
(>1.008) - Dextrose

FACTORS AFFECTING HEIGHT OF BLOCK
DRUG FACTORS
 DOSE -greater the dose higher is the block. Drug spreading stops in
20-25 mins after injection
 VOLUME-Increasing the volume of fixed concentration will also
lead to higher blocks. Additive drugs other than opioids do not affect
spread.
- Opioids seem to increase mean spread as a result of pharmacological
enhancement at the extremes of spread where LA alone would have been
subclinical.
 BARICITY-height of block is likely to extend a few segments
higher when hyper baric solutions are used. Dextrose and sterile water
added to make drug hyperbaric and hypobaric respectively.
 CONCENTRATION
 TEMPERATURE- Density varies inversely to temperature

PROCEDURE FACTORS
 POSITION of patients during injection:-
In sitting position:-heavy solutions tends to fall, hypobaric solutions
tend to rise
In lateral position:- after patient turned supine, hyper baric solution
move cephalad or caudal depending upon the tilt of table.
CHOICE OF INTERSPINOUS SPACE-
Higher interspace chosen when higher blocks desired.
RATE OF INJECTION- injection produces higher block than
expected(0.2ml/sec).Slower injection increases the spread
 LEVEL OF INJECTION does not appear to influence the spread of
hyperbaric solutions( affected by isobaric)
 Needle type and alignment- When directing needle orifice to one side a
more marked unilateral block is achieved with Whitacre needle rather
than Quinke’s.

PATIENT FACTOR-
 CSF VOLUME- inversely propotional to the block height.
Obesity and increased epidural fat may decrease CSF volume leading
to increase spread
 OLD AGE- A/W increased block height as CSF volume decreases,
specific gravity increases and nerve roots appear more sensitive to
LA
 SEX- CSF density is higher in males, thereby reducing baricity of
drug and limiting the cephalad spread
 HEIGHT- within range of normal sized adult patients height does
not seem to affect the spread as the length of lower limb bones
rather than vertebral column contributes most to adult heighta
 PREGNANCY-lower dosages are required.
 WEIGHT- in obese CSF volume decreases causing increase
cephalad spread

 ANATOMIC SPINE CONFIGRATION-
-Drug travels along gravity to the most dependent part
-Scoliosis- makes needle insertion difficult will have little effect on
spread
-Kyphosis-affects the cephalad spread
BARBOTAGE-Repeated aspiration and reinjection of CSF
This is technique of stirring up of drug solution with CSF to increase
turbulence, mixing of injected solution and increase distribution in
subarachnoid space.
It is not consistently associated to affect the block height.
NOT AFFECTING LEVEL OF BLOCK-
-Height -Addition of vasoconstrictor

ORDER OF BLOCKADE OF NERVE
FIBRES
 pre ganglionic B fibers
 Temperature fibers (cold C fibers).
 Pin prick fibers (A delta)
 Touch fibers( A beta )
 Deep pressure fibers
 Somatic motor fibers(A alpha)
 Vibratory sense and propioception

Sequence of nerve modality block
1. Vasomotor block – dilatation of cutaneous vessels
and increased cutaneous blood flow
2. Block of cold temperature fibres
3. Sensation of warmth felt by the patient
4. Temperature discrimination is lost
5. Los of slow pain
6. Loss of fast pain
7. Tactile sensation is lost
8. Motor paralysis
9. Pressure sense abolished
10. Proprioception and joint sense is lost

ASSESMENT OF BLOCK
 Sympathetic block can be assessed by measuring skin
temperature,sensory block by pin prick and motor block by
reference to
modified Bromage scale, this scale has 4 grades:-

Complication of neuraxial
anesthesia
INTRAOPERATIVE
 Headache
 Hypotension
 Bradycardia
 Apnea
 Nausea vomiting
 Aphonia
 Cardiac arrest
 High or total spinal block
 Respiratory depression
 Pruritis
 Shivering
 Neurological complications
POSTOPERATIVE
•Urinary retention
•Post dural puncture
headache
•Backache
•Infection
•Intracranial complications

COMPLICATIONS AND SEQUELAE
 HYPOTENSION:-
Results from sympathetic nervous system block that
-Decreases venous return to heart and decrease cardiac output
-Decreases systemic vascular resistance
Prevented by: Volume Pre loading with 10-20 mL/kg of intravenous
fluid
Predictors of hypotension-
low intravascular volume in case of hypovolemic due external
loss by trauma, dehydration, internal loss
sensory block ≥ T5
age > 40 years
systolic BP < 120 mm Hg
combined spinal and general anesthesia
dural puncture between L2-3 and above
pt with h/o uncontrolled hypertension
underlying autonomic dysfunction

TREATMENT
Oxygen inhalation
Increase speed of I.v crystalloid/colloid infusions
If associated with bradycardia , give atropine.
Appropriate vasopressors.
SYMPATHOMIMETICS:
 Epinephrine: increases HR, CO, SBP, decrease
DBP.
 Phenylephrine: Increase in SVR, SBP, DBP. Causes
reflex bradycardia, coronary blood flow increased.
 Ephedrine; increase myocardial contractility
 Mephenteramine

• Post dural punture headache
 Due to leak of CSF from dural defect leads to traction in
supporting structure especially in dura
 Postural in nature increase in sitting and relieved in lying down
position. Most PDPHs develop 24 to 72 hours after dural puncture.
 Occur in frontal or occipital region, pain and stiffness in neck may
be present. Headache may last days, weeks or months but usually 1-
2weeks.
 Average loss of CSF is 10ml/hr.
Types
-Low CSF pressure PDPH occurs due to CSF leakage
-High CSF pressure due to meningeal irritation by chemicals or
microbes.

Loss of CSF
intracerebral CSF volume decreases.
brain to sag toward the foramen magnum
stretching the pain-sensitive meningeal
vascular covering.
Compensatory increase in cerebral blood volume
vascular headache.
MECHANISM OF PDPH

TREATMENT
PROPHYLACTIC:-
Smaller the needle gauge, lower the incidences of headache.
Needle point having pencil point tip as in Whitaker type has lower
incidences of PDPH.
Orienting needle bevel parallel with axis of spine.
Maintain hydration and Early ambulation
TREATMENT OF ESTABLISHED CASES OF PDPH
Simple analgesics(NSAIDS)and Bed rest
Frequent caffiene drinks.
Injection of 10-20ml of autologous blood into extradural space to
form a blood patch for sealing of dural puncture.(Epidural blood
patch)
Oxygen inhalation.

 BACKACHE
Relatively infrequent
May be related to procedure itself
Small hematomas, ligamentous irritation, reflex skeletal muscle
spasm and even anesthesia positioning are other possibilities
TREATMENT
REASSURANCE
REST
HEAT
ANALGESICS.
 URINARY RETENTION
Blockade of S2-S4 is associated with loss of bladder tone and
inhibition of voiding reflex.
TREATMENT
CATHETERIZATION

 HIGH SPINALANAESTHESIA
As the level of sensory anaesthesia ascends ,there is hypotension, aphonia
altered sensorium profound bradycardia and respiratory insufficiency occurs
due to blockage of cervical nerve roots
FACTORS RESPONSIBLE
 Total dose injected.
 Position of patient
 Obesity
 Short stature
TREATMENT
 Support airway and circulation.
 Supplemental oxygen along with assisted ventilation may be required.
 Decrease in BP and HR should be treated by I.v fluids , vasopressors
and/or atropine.
 TOTAL SPINAL- cerebral hypoxia due to drug reaching the
cranial sub arachnoid space leading to ischemia of vital control centres
and cranial nerve palsies.

• CARDIAC ARREST
• If the block progresses (High Spinal) to the mid thoracic
region involving the heart.
• Usually due to hypoxaemia <85% without obvious changes in
respiration and cyanosis.
• Use of fentanyl, can account for bradycardia and arrest
• Incidence is commoner in young healthy adults, preceded by
bradycardia.
• Treatment-conventional doses of atropine and ephedrine is
given
• Full resuscitation dose of epinephrine is given

NEUROLOGICAL COMPLICATIONS
(1)PARALYSIS OF ISOLATED NERVES:-
Cranial nerves
 Most commonly involved nerve is Abducens(6th).
Incidence is 1 in 300.
Onset is 5th to 11th post operative day.
Causes:-
-Mechanical changes in hydrodynamics of CSF.
-Inflammatory low grade meningitis.
-Toxicity due to drug.
Clinical features:-
-Blurred vision, diplopia,preceded by disabling headache.
-Dizziness.
-Photophobia.
Treatment:-symptomatic
-Dark glasses with outer third of the glass made opaque.
-50% recover in a month.

(2)MENINGITIS
 ASEPTIC MENINGITIS-CAUSED BY INFLAMMATORY
MENINGEAL REACTION.
-Occurs suddenly and usually in 3 or 4th operative day
- It presents as intense splitting headache ,stiffneck,
,photophobia,confusion and vomting.
-Usually subside with use of aspirin and antibiotics
 INFECTIVE -INADEQUATE OR FAULTY ASEPSIS.
 M/C ORGANISM- S. VIRIDANS

(3)MISCELLANIOUS COMPLICATIONS
•Spinal cord and nerve root damage.
•Transverse myelitis.
•Cauda equina syndrome.
•Chronic adhesive arachnoiditis.
•Bulbar involvement.
•Paraplegia.
•Pathological changes in spinal cord.
•Anterior spinal artery syndrome.

•CONTRAINDICATIONS
Absolute
• Patient Refusal
• Infection At The Site Of Injection
• Coagulopathy And Other Bleeding Disorders
• Severe Hypovolemia
• Increased Intracranial Pressure
• Severe Aortic Stenosis/Severe Mitral Stenosis
•Relative
• Sepsis,psychiatric disorders
• Uncoperative Patient
•Uncontrolled hypertension
• Preexisting Neurological Deficits
• Severe Spinal Deformity
• Thrombocytopenia
•Controversial
• Prior Surgery At The Site
Of Injection
• Complicated Surgery
• Prolonged Operation
• Major Blood Loss

PAEDITRIC SPINALANAESTHESIA
ANATOMICAL DIFFERENCES:-
Up to end of first year of life-
Spinal cord end at L3 level.
Dural sac ends at S3-S4.
Up to end of 2nd yr. Of life-
Spinal cord end at L1 level.
Dural sac ends at S2.
INDICATIONS:-
o For surgery of lower part of body like irreducible inguinal
hernia repair, lower limb surgeries.
o Useful in neonates with respiratory distress syndrome.
o Risk of postoperative apnea due to general anaesthesia is
avoided.
DOSE REGIME:-
0.5 TO 0.75ml of 0.5% bupivacaine for 2-5kg infant.

Saddle block
It is the subarchnoid block given in sitting position and patient
remains seated for upto 30 mins since most of the drug
migrates downwards and only sacral segments are blocked.
 Used in perianal surgeries like hemorrhoids, fistula in ano
and anal fissures
Advantages -:
 Minimal hemodynamic fluctuations and high spinal risk.
 Early ambulation

EPIDURALANAESTHESIA
 DEFINITION
Its an anaesthesia technique obtained by blocking spinal nerves in the
epidural space,as the nerves emerges from the dura and then passes through
the intervertebral foramina
 ANATOMY OF EPIDURAL SPACE
Boundaries of epidural space-
Superior -Foramen magnum.
Inferior -Sacrococcygeal ligaments.
Posterior-Anterior surface of lamina and their
connecting ligaments, root of vertebral
spines,and ligamentum flavum
Anterior-Posterior longitudinal ligaments covering the
vertebral bodies and ligaments.
Lateral -Pedicles and intervertebral foramen.
Contents – Dural sac, spinal nerve roots, extradural plexus of veins, spinal
arteries, lymphatics and fat.

STUCTURES PENETRATED WHILE MAKING A MIDLINE
APPROACH TO EPIDURAL SPACE.
(1) skin and subcutaneous tissue.
(2) Supraspinous ligament.
(3) Interspinous ligament.
(4) ligamentum flavum.
 In the cervical and lumber region, the spinous processes are more
horizontal. However in thoracic region they are oblique that’s why a
Para median approach is recommended for midthoracic injection.
Epidural space under six year of age contains spongy, gelatinous
lobules and have distinct spaces, this is in contrast to densely packed
fat globules and fibrous strands which is a characteristic of mature
epidural space. Because of this difference there is a more rapid
longitudinal spread of drugs within the juvenile epidural space.

FACTORS INFLUENCING SPREAD OF ANAESTHETIC
SOLUTION IN EPIDURAL SPACE
 Dose, volume and concentration of local anesthetic used.
 Patients age-Older patient requires less drug than the younger
ones.
 Gravity-a head down tilt of the table aids cephalad diffusion and
vice versa.
 Height-a 5 ft patient requires dose of 1ml/segment, which can vary
up to 2ml/segment for the taller patients.
 Full term pregnancy or abdominal tumors- One third to half of
total dose is required. This difference is because, in such cases
epidural venous plexus is markedly distended.

TECHNIQUES TO IDENTIFY OF EPIDURAL SPACE
 SUDDEN LOSS OF RESISTANCE TO THE ADVANCING NEEDLE.
 SUDDEN EASE OF INJECTING LITTLE AIR OR LOCAL ANAESTHETIC
FROM A FREELY RUNNING SYRINGE ATTACHED TO THE NEEDLE.
 SUCKING OF HANGING DROP OF SALINE ON THE HUB OF THE
NEEDLE.
 ULTRASONIC LOCALIZATION.
OXFORD EPIDURAL SPACE INDICATOR –
-3-5ml of lignocaine containing epinephrine is injected.
- if test dose is intravascular the heart rate increases 20% within 30-
60sec,a subarachnoid injection produces signs of block within
3mins.

EQUIPMENTS FOR THE EPIDURAL BLOCK
Epidural needle:-
 The standard epidural needle is typically 16-18G, 9cm long and has
blunt bevel with a gentle curve of 15-30 degree at the tip for ease of
passing catheter
 The most common version of this needle is referred to as Tuohy
needle and the curved tip is referred as Huber tip.
Other types are:-
 Hustead needle
 Crawford needle-thin walled, straight blunt bevel
 Scott needle-provided with introducer devices.
 Weiss needle-containing wings at the junction of shaft of the
needle.

Epidural catheters:-
•Usually comes in sizes of 16 and 18G.
•Made of NYLON/POLYAMIDE
•The internal diameter of the catheter should be large as possible to
minimize the resistant to injection.
•Total length of catheter is 90cm .
•Have 2 or more holes within 2cm of end and a closed rounded tip
which prevents puncture of the blood vessels.
•Most catheters are marked at 5cm intervals from the tip ,and some are
marked every cm Up to 10cm.
Filters:-
The prime function of filter is to exclude bacteria and particles as
small as 0.22micrometer.

LOCALANAESTHETIC SOLUTIONS FOR
EPIDURAL BLOCK
 Lignocaine:- 1-2%,it has rapid onset in about 10 minutes and
gives good relaxation , duration of effect is 1-2 hr. Lignocaine and
bupivacaine can be given in mixture.
 Bupivacaine:-long acting ,used in 0.5% concentration ,give
analgesia for up to 8hrs.
 Prilocaine:-less toxic than lignocaine ,doses in excess of 600mg
may cause cyanosis from methahemoglobinamia.
 Ropivacaine:- 0.25 -1%
 Chloroprocaine:-short latency and duration of action(about
45mins),its effect ceases suddenly.
 Epinephrine is frequently added to local anaesthetic solution in
order to increase the depth of blockade and significantly prolong
the duration of anaesthesia.

VOLUME OF BUPIVACAINE REQUIED FOR EPIDURAL
BLOCK
Maximum safe dose is 3mg/kg(25-30ml 0.5% solution in the average
adults).
 0.75% gives slightly more profound effect and 0.25%is useful for post
operative pain relief.
 Average dose for lower abdominal and lower limb surgeries is 15-20ml
of 0.5% solution.
 DOSES FOR LABOUR ANALGESIA:
(1) Intermittent bolus-
DRUG DOSE ONSET DURATION
BUPIVACANE 0.25% 8-12ml.
0.125% 10ml.
0.5% 4-6ml.
8-15min 90-120min.
60min.
LIDOCAINE 1% 10ml.
1.5-2% 10ml.
3-5min 60min.

(2) Continuous infusion-
•Administer one of the bolus doses then infuse 0.0625% bupivacaine
with 1-2ml/segment.
•Fentanyl at 10-12ml/segment.
• TSUI TEST- To confirm the catheter position
•The test stimulates the spinal roots with low voltage current conducted
through normal saline in epidural space and electrically conducting
catheter
•At current about 1-10 mA via nerve stimulator corresponding muscle
twitches are noted to identify catheter position

ADJUVANTS TO EPIDURAL BLOCK
 Sodium bicarbonate(with lidocaine)
 Epinephrine , clonidine and dexmedetomidine.
Clonidine and dexmedetomidine (intensify and prolongs the
effect also provide postoperative analgesia)
 Sedation is common
 Opioids – fentanyl ,sufentanyl and morphine

INDICATIONS FOR EPIDURAL BLOCK
 Upper abdominal operation
 In lower abdominal & PERINEAL operations.
 Hernia repair.
 Operations on the lower limb
 Obstetric analgesia.
 Post operative pain relief.

COMBINED SPINAL- EPIDURAL ANESTHESIA
 Combined spinal-epidural anesthesia is a technique in which a
spinal anesthesia and epidural catheter are placed concurrently.
 This approach combines the rapid onset and intense sensory
anesthesia of a spinal anesthesia with ablity to supplement and
extend the duration of block afforded by an epidural catheter.
 Also to provide post operative analgesia after procedure
 Needle through Needle technique most common
 Performed at L3-L4/L4-L5 interspaces.(conus upto L2/L3)
 After identifying the epidural space with the usual LOR
technique insert a long small guage spinal needle through the
epidural needle, a pop up felt as dura is entered.
 Stablize both needles, withdraw stylet, look for CSF and inject
the SAB drug
 Withdraw the spinal needle and insert epidural catheter.

•EVE(EPIDURAL VOLUME
EXPANSION)
•The addition of either LA or
normal saline in the epidural space
via catheter after giving low dose
spinal compresses the dural sac and
increases the block height
•Useful in caesarean deliveries

CAUDAL EPIDURAL ANAESTHESIA
 DEFINITION:-
The caudal space is the sacral portion of the epidural space. Caudal
anaesthesia involves needle or catheter penetration of Sacrococcygeal
membrane covering the sacral hiatus that is created by the unfused
posterior S4-S5 lamina.
 However, in adults approximately twice the lumbar epidural dose is
required to achieve a similar block with the caudal approach. The
spread is also variable, making this technique in adults unreliable for
procedures above the umbilicus.
o ANATOMY:-
 The sacral hiatus may be felt as a groove above the coccyx and
between two bony prominences called cornu. Its anatomy is more
clear in children upto 6yrs
 The posterior superior iliac spines and sacral hiatus make an
equilateral triangle.

 Within the sacral canal, the dural sac extends to the 1st sacral
vertebra in adults and to about 3rd sacral vertebra in infants, making
inadverant intrathecal injection more common in infants.
INDICATIONS:-
 Mainly used in pediatric patients (upto 6 yrs) for procedure below
umblicus Including urogenital, rectal, inguinal and lower extremity
surgeries.
 It can be combined with general anaesthesia in children for post
operative pain relief.
 Also can be used in anorectal surgeries in adults.
CONTRAINDICTION
 Major malformation of sacrum( myelomeningocele ,open spina
bifida)
 Meningitis
 Intracranial hypertension

TECHNIQUE
(5) There are three main approaches:
THE PRONE, THE SEMI-PRONE, AND THE LATERAL.
The choice depends on the preference of the anesthesist and the degree
of sedation of the patient. The caudal space is made more prominent by
asking the patient to internally rotate their ankles.
 The semi-prone position is preferred for the anesthetised or heavily
sedated patient as the airway is easier to control in this position, while
still allowing reasonably easy access to the sacral hiatus.
 The lateral position is often used in children, as the landmarks are
easier to find than in adults. Care should be taken to avoid over
flexing the hips (as for lumbar epidurals) as this can make the
landmarks more difficult to palpate.

 6) The landmarks are palpated. The sacral hiatus and the posterior
superior iliac spines form an equilateral triangle pointing inferiorly.
-The sacral hiatus can be located by first palpating the coccyx, and
then sliding the palpating finger in a cephalad direction until a
depression in the skin is felt.
 The caudal needle is inserted at an angle of approximately 45
degrees to the sacrum.
 While the needle is advanced, a decrease in resistance to needle
insertion should be appreciated as the needle enters the caudal canal

 The needle is advanced until bone is contacted
and then is slightly withdrawn, and the needle is
redirected so that the angle of insertion relative
to the skin surface is decreased.
 In male patients, this angle is almost parallel to
the coronal plane; in female patients, a slightly
steeper angle (15 degrees) is necessary.
 During redirection of the needle, loss-of-
resistance is sought to confirm entry into the
epidural space, and the needle advanced no more
than approximately 1 to 2 cm into the caudal
canal..
 Confirmation by WHOOSH
TEST(AIR)/SWOOSH TEST(SALINE OR LA)

ORIENTATION OF NEEDLE AND RE ORIENTATION
AFTER CROSSING SACROCOCCYGEAL LIGAMENT

Armitage formula
 For caudal dosing in paediatrics
Bupivacaine/lignocaine
 0.5ml/kg – all sacral dermatomes block
e.g.circumcision
 1.0ml/kg –all sacral and lumbar
dermatomes block
e.g. ingunial hernia
 1.25ml/kg -- midthoracic block(upto T4)
 1.5 ml/kg -- midthoracic block with
lignocaine
Maximum upto 20ml/20kg

COMPLICATIONS
 Intravascular or intraosseous injection: This may lead to
seizures and/or cardio-respiratory arrest.
 Dural puncture: Extreme care must be taken to avoid this as a total
spinal block will occur if the dose for a caudal block is injected into
the subarachnoid space. If this occurs then the patient will become
rapidly apnoeic and profoundly hypotensive.
 Perforation of the rectum: Contamination of the needle is
extremely dangerous if it is then inserted into the epidural space.
 Sepsis: This should be a very rare occurrence if strict aseptic
procedures are followed.
 Urinary retention.
 Haematoma
 Sacral osteomyelitis- rare
 Delayed respiratory depression

CONTRAINDICATIONS OF NEURAXIAL BLOCKS
 ABSOLUTE:-
 Patients refusal.
 Infection at the site of injection.
 Allergy to the drug
 Increased intra cranial tension.
 Patient inable to maintain position

 RELATIVE:-
 Generalized sepsis
 Coagulopathies and other bleeding diathesis or on
anticoagulants
 Severe aortic stenosis and mitral stenosis
 Uncooperative patient
 Platelets counts less than 80,000
 Preexisting neurological deficits and demyelinating
lesions.
 Stenotic valvular heart diseases.
 Severe spinal deformity.

Neuraxial block

More Related Content

What's hot (20)

Similar to Neuraxial block (20)

Recently uploaded (20)

Neuraxial block