Regional anesthesia1

College of medicine and health
science
Department of Anesthesia
Regional anesthesia
By: kanbiro G.
kanbgedeno45@gmail.com

Outlines
 Objectives
 Definition of regional anesthesia
 Types of neuro-axial blocks
 The anatomy of vertebral column
 Technique of spinal anesthesia & its
complication
05/23/2019
Kanbiro G.
2

objectives
At the end of this topic, you will able to:
 Explain the vertebral column anatomy and blood supply
 Assess patient for SA
 Prepare Pt, drugs & necessary equipment's for SA
 Perform lumbar puncture under sterile technique
 Determine level of spinal block
 Manage spinal anesthesia perioperative including complication
05/23/2019 kanbiro G. kanbgedeno45@gmail.com 3

Definition
Regional anesthesia can be defined as Any
technique to induce the absence of sensation in
part of the body.
05/23/2019
kanbiro G.
4

Types of regional anesthesia?
 Topical
 Intravenous (Bier’s) block
 Peripheral nerve block
 Neuro-axial block

Neuro-axial blocks
 Spinal anesthesia
 Epidural anesthesia
 Caudal anesthesia

Anatomy of vertebral column
Extends from skull to the pelvis
 33 total vertebrae:
 7 C, 12 T, 5 L, 5 S (Fused as Sacrum),
4 coccygeal
 Superiorly: 24 individual vertebrae
(separated by intervertebral discs)
 Inferiorly: 9 fuse to form 2
composite bones 5 S & 4 C.

Vertebral column: function:
 Transmits weight of the trunk
to the lower limbs
 Surrounds/protects spinal cord
 Attachment point for the ribs
and muscles of neck and back

Osteology:
Typical vertebrae
 Body
 Vertebral Arch
 Spinal Foramen
 Intervertebral Foramen

Osteology: vertebral body
 Largest portion of the
vertebra
 Weight bearing purpose
 Increases in size towards
lumbar

Osteology: vertebral arch
The vertebral arch consists of:
 A pair of pedicles.
 A pair of lamina.
 7 processes:
 Spinous ----one
 Transverse ---two
 Facets ....four

Pedicles:
 Short, thick processes pass backward from the
junction of lateral and posterior surfaces of the
body.
 Connects the vertebral
arch to the body

Lamina:
 Broad plates of bone lying behind and medial to
pedicles.
 They fuse behind in the median
plane into the spinous process.
 They form posterior boundary
of vertebral foramen

Spinous process:
 Starts on lamina fusion
 Attachment for vertebral muscles and
ligaments

Spinous process:
Thoracic vs lumbar spinous process
 Thoracic spinous processes are long and
inclines slightly downward.
 Lumbar spinous processes are short, flat and
quadrangular.

Transverse process:
 Start at the fusion of lamina and pedicles
 Also used for attachment
of muscle and ligaments
 T1 –T10 has costal facets
which articulates with
tubercles of ribs 1-10

Superior articular process:
 Project upwards from the junction of laminae
and pedicles.
 Forms joint with inferior
articular process –sitting
position opens the space

Inferior articular process:
 Projects downward from the junction of the
pedicle and lamina.
 Forms articular joint with superior articular
facet.

Vertebral foramina:
2 foramens:
Vertebral foramina –formed by the vertebral body
and arch
 Spinal cord and nerves
pass through
 Thoracic –circular
 Lumbar –triangular

Intervertebral foramen:
 Serves for passage for spinal nerves and
intervertebral arteries to supply the root and
spinal cord.

Arthrology: vertebral column
 Intervertebral Discs
 Fibro cartilaginous joints
 Increase in size from C to L (3mm to 9 mm)
 Make up 20-30% of length of column

Intervertebral disk:
 Formed by fibro-cartilaginous structure and
used as ligament that hold the bodies together.

Intervertebral discs -Annulus fibrous:
 Fibrous tissue and fibro-cartilage.
 Annulus totally encloses the nucleus and keeps
it under constant pressure.

Intervertebral discs –nucleus polposus:
 Jelly like substance.
 About 80-90% water, less with increased age.
 Nucleus, when under extreme pressure, can
herniate or extrude from the disc in a posterior
or posterior-lateral direction.

Ligaments: vertebral column
Major ligaments in the spine:

A and P longitudinal ligaments

Anterior Longitudinal Ligament -ALL
 Dense band along anterior and lateral surface
of the vertebral bodies.
 From C2 to sacrum.
 Limits extension of Vertebral column.

Posterior longitudinal ligaments
 Runs along posterior surface of vertebral bodies
(anterior to spinal canal).
 C2 to Sacrum.
 Short fibers attach ligament to posterior disc,
reinforce disc posteriorly.
 Limits flexion.

Supraspinous ligaments
 Spinous process to spinous process –tip to tip
 C7 to sacrum
 Limits flexion
 In cervical region, become
much thicker with a greater
elastic content Called
Ligamentum Nuchae

Interspinous ligament
 Found between spinous processes.
 Most well developed in lumbar region support.

Ligamentum fluvum
 Connects lamina of one to lamina of the other
 Found from axis to sacrum
 Limit flexion
 Continuation to the skull is called Posterior
Atlanto-Occipital membrane

Spinal meninges
The spinal meninges consists of three
protective membranes which are continuous
with the cranial meninges. They are:
 Dura mater
 Arachnoid mater
 Pia mater

Dura mater
 The outermost and thickest meningeal layer
 It extends foramen magnum and ends at the
level of S2 where it fuses with the filum
terminale.
 The Dura is thickest in the posterior midline
and thinner in the lumber area.

Arachnoid mater
 It is a delicate avascular membrane which lies
next to the Dura matter.
 Thin membrane that encloses the subarachnoid
space and CSF.
 It is continuous with the cerebral arachnoid,
which loosely invests the brain, and dips into the
longitudinal fissure between the cerebral
hemispheres.

Piamater
 It is the innermost layer of the 3 membranes.
 It is a vascular connective tissue sheath that
closely invests the brain & spinal cord, and
projects into their sulci and fissures.
 The pia matter extends up to the tip of the
spinal cord where it becomes filum terminale
which anchors the spinal cord to the sacrum.

Subarachnoid space
 It is the space that lies between the arachnoid
matter and pia matter
 It contains the CSF.
 Its contents are CSF, nerve roots, blood vessels
that suply the spinal cord.

Subdural space
 The arachnoid is in close contact with the dural sheath
& is separated from it by a thin film of serous fluid.
 Accidental placement of a catheter during epidural
anaesthesia and subsequent injection of local
anesthetic results in patchy anesthesia which is often
unilateral and extensive.

Epidural space
 It is a space in the spinal canal that is occupied by dura and
its contents.
 It Extends from the foramen magnum to end by the fusion of
its lining membranes at the sacrococcygeal membrane.
 It contains fat, vessels , nerve and lymphatics.
 The distance from the skin to the lumbar epidural space in the
midline is on average about 5 cm

Cerebrospinal fluid (CSF)
 The CSF is the clear watery fluid contained
within the cerebral ventricles and the
subarachnoid space.
 The total volume of CSF
is about 100 to 160ml.

CSF
 CSF is an ultra filtrate formed by active process from the choroid plexus
of the lateral ventricles.
 The epidymal cells of pia covering the blood vessels play the secretary
role.
 At 600ml of CSF is formed per day.
 About 20-25 ml of CSF is present in the ventricles.
 90 ml of the CSF in reservoirs in the brain.
 25-30 ml of CSF occupy the sub arachnoid space

CSF
 The specific gravity of CSF is 1.003-1.009
 Its PH is 7.4 -7.6
 Sodium -140-150 meq/L
 Chloride -120-130 meq/L
 Bicarbonate -25-30 meq/L
 Proteins –15-45 mg/dl
 Glucose –50-80 mg/dl

Blood supply of the spinal cord
 The spinal cord is supplied by the anterior and posterior spinal
arteries which both descend down from the level of the foramen
magnum.
 Anterior spinal artery :single
supply 2/3 of the spinal cord
From the vertebral artery
 Posterior spinal artery :paired
supplies posterior 1/3 of the
spinal cords
From the posterior inferior
cerebellar arteries.

Spinal nerves
 There are 8 cervical nerves(C), 12 thoracic(T), 5 lumbar (L), 5 sacral
(S), and 1 coccygeal.
 Each is formed by the fusion of
An anterior & posterior spinal root.
 Each pair of spinal nerves
passes through a pair of
intervertebral foramina.
 Cauda equina

Dermatomal levels for common procedures

Mechanism of action of neuraxial blocks
 The principal site of action for neuraxial blockade
is believed to be the nerve root.
 Local anesthetic is injected into CSF (spinal
anesthesia) or the epidural space (epidural and
caudal anesthesia) and bathes the nerve root in the
subarachnoid space or epidural space, respectively.

 Nerves in the subarachnoid space are highly accessible and
easily anesthetized, even with a small dose of local anesthetic,
compared with the extradural nerves, which are often
ensheathed by dura mater (the “duralsleeve”).
The speed of neural blockade depends on:
– The size of nerve fibers
– The concentration achieved and the duration of contact
– Degree of myelination of the nerve fibers.

 Smaller and myelinated nerve fibers are generally more
easily blocked than larger and unmyelinated ones.
 Results ‘differential block’.
Sympathetic Block
 2-6 dermatomes higher than the sensory block
Motor Block
 2 dermatomes lower than sensory block

Physiologic effects of neuraxial blocks
Cardio vascular manifestations:
Neuraxial blocks effects are generally proportional to the
dermatomal level and extent of sympathectomy.
 Decrease in blood pressure
 Decrease in heart rate
 Decrease in cardiac contractility
 Decrease in SVR

Pulmonary manifestations:
 Alterations in pulmonary physiology are usually minimal with
neuraxial blocks because the diaphragm is innervated by the
phrenic nerve.
 Even with high thoracic levels, tidal volume is unchanged; there is
only a small decrease in vital capacity.
 But in Patients with severe chronic lung disease ,high levels of
neural blockade will impair accessory respiration muscles.

Gastro intestinal manifestations:
 Neuraxial blockade from T6 to L1 disrupts
splanchnic sympathetic innervation to the
gastrointestinal tract, resulting in a contracted gut
and hyperperistalsis.
 Nausea and vomiting may be associated with
neuraxial block in as much as 20% of patients

Urinary tract manifestations:
 Neuraxial anesthesia at the lumbar and sacral
levels blocks both sympathetic and
parasympathetic control of bladder function.
 Loss of autonomic bladder control results in
urinary retention until the block wears off .

Spinal anesthesia
 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.
 The anesthesia provider places the needle below L2
in the adult patient to avoid trauma to the spinal cord.

Indications of spinal anesthesia
 Used both alone and in combination with either GA or
sedation.
 Lower limb orthopedic surgery on the pelvis, femur , tibia
and ankle.
 Total hip replacement.
 Total knee replacement.
 Lower limb vascular surgery

 Hernia (Inguinal or epigastric).
 Haemorrhoidectomy , fistula , fissure.
 Nephrectomy and cystectomy in combination with GA.
 Transurethral resection of the prostate and transurethral resection of the
bladder tumors.
 Abdominal and vaginal hysterectomies
 Laparoscopic assisted vaginal hysterectomies(LAVH) combined with GA.
 Caesarean sections

Contraindications
ABSOLUTE
 Patient refusal
 Infection at the site of injection
 Coagulopathy or other bleeding diathesis
 Severe hypovolemia
 Increased intracranial pressure
 Severe aortic stenosis
 Severe mitral stenosis

Relative
 Sepsis
 Uncooperative patient.
 Pre-existing neurological disorder.
 Fixed cardiac output states (AS, MS,).
 Anatomic abnormalities.
 Prophylactic low dose heparin use

Advantages of spinal anesthesia over GA
 Minimal cost
 Patient satisfaction
 Reduced respiratory disease
 Muscle relaxation
 Minimal bleeding
 Post operative analgesia
 Prevent production of stress hormone
 Avoid general anesthesia related complications

Pre operative patient selection and preparation
Patient may be offered spinal anesthesia when:
 Its expected enough for planned procedure.
 In the judgment of the anesthetist that the
patient is an appropriate candidate for
anesthesia.

Core pre-anesthetic Hx, PE, and lab:
 Assessment should be the same as for GA
 Complete medication history
 Coagulation profile maybe indicated if the patients are taking major
anticoagulant medications
 Any abnormalities in neurological Hx. and examinations should be documented
 The planned lumbar puncture site and bony land marks should be examined to
confirm that SA anesthesia is technically feasible.

 Lab. Investigations: particularly coagulation
profile
 Premedication
 Preloading and co-loading
 Resuscitation equipment should be at hand

Safe spinal techniques
Preparation
Position
Projection
Puncture

Preparation
Equipment preparation
Spinal tray:
 Two 5cc plastic syringe
 24-25 G pencil point needle + Introducer.
 18 G blunt drawing up needle.
 26 G (40 mm) needle for lidocaine infiltration.
 Galley pot + Betadine solution (alcoholic povidone/iodine/savalone).
 Sterile drapes.
 Small pack of gauze squares.
 Sterile gloves.
 A sticking plaster

Preparation
Equipment preparation
Other equipment:
 16 or 18 G intravenous cannula + intravenous fluid
infusion.
 Monitors (Pulse oximetry, ECG, BP).
 Oxygen via mask or nasal prongs
 GA Equipment and drugs

preparation
NEEDLES:
 The standard spinal needle-
Three parts: Hub , cannula, stylet
 Points of cannula are beveled and
have sharp edge Cannula made of
stainless steel Sizes-16 G to 30 G
 Length-3.5 to 4 inches

Type of spinal needles:
They can be divided into either sharp (cutting)-tipped or blunt-tipped needles.
 The Quincke needle is a cutting needle with end injection.
 The Whitacre needle is pencil-point needles have rounded points and side
injection
 The Sprotte needles is a pencil point side-injection needle with a long opening.
It has the advantage of more vigorous CSF flow compared with similar gauge
needles.

Drug preparation
Local anesthetic agents and adjuvants.
Selection of specific local anesthetic drug based
on:
 Site of surgery
 Duration of surgery
 Desired intensity of motor blockade
 Baracity of drug:
hyperbaric
Isobaric
hypobaric

Type of block Hyperbaric
bupivacaine(0.5
%)
Plain
bupivacaine(0.5
%)
Hyperbaric
Lidocaine(5%)
Saddle block,
eg operations
on genitalia,
perineum
2ml 3ml 1ml
Lumbar block,
eg operations
on legs
3-3.5ml 3-3.5ml 2ml
Mid-thoracic
block, eg hernia,
hysterectomy
3-4ml 3-4ml 2ml

Patient preparation
Intravenous pre-loading:
 Large IV cannula
 IV fluids immediately before the spinal
 The volume of fluid given will vary with age and
extent of block
 Ideally –10ml/kg
 Crystalloids like Ringer lactate , 0.9% normal
saline are used
 Now co-loading.

Patient preparation
Cleaning and draping:
 Clean the skin surface inside to outside with
prepared solutions and sterile gauze

Preparation
1. Scrub hands according to aseptic surgical technique
2. Use sterile glows
3. Avoid contaminating blocking solutions with solutions used to
prepare the skin.
4. Use aseptic technique when opening tray.
5. Clean the skin prior to needle puncture.
6. Touch only sterile articles once gloved.
7. Use introducer prior to injection of small gauge spinal needle.
8. Use approved local anesthetic agents in standard
concentration

Positioning
 L.P. is most easily performed when there is
maximum flexion of lumbar spine.
By this ligaments get stretched and space is open.
sitting
lateral
prone

Sitting position:
 The anatomic midline is often easier to approach when the
patient is in sitting position .
 Patient sit with their elbows resting on their thighs or
bedside table or they can hug a pillow.
 Flexion of spine maximizes the target area between adjacent
spinous processes and brings the spine closer to skin surface

Sitting position

Lateral position
 Spinal canal should be on horizontal plane
 Operator should fix his or her gaze on the horizontal
plane.
 Flexed lateral position-back should be parallel to the
edge of the table, knees are flexed on the abdomen,
neck flexed.

Lateral position

Jack knife position(prone):
 This position is used for anorectal procedures
utilizing a hypobaric anesthetic solution.

Projection
Land marks:
 Vertebral Spinous processes and the iliac
crests
 Spinous processes clearly define the midline
Line drawn between the iliac crests-
intercristine or Tuffier’s line crosses the
4thlumber vertebrae.

Puncture
Approach for spinal anesthesia
Midline approach:
 The most common approach, the needle or
introducer is placed midline, perpendicular to
spinous processes, aiming slightly cephalad.

Technique:
 The depression between the spinous process of the vertibra above and
below the level to be used .
 the needle will be directed cephalad
 The subcutaneous tissue gives feeling of little resistance to the needle,
 After that needle will enter the supra spinous and infra spinous
ligaments felt as an increase in tissue density .
 As the needle meets the ligamentum flavaman increase in resistance is
encountered and on piercing it, loss of resistance can be felt .
 The needle is advanced through the epidural space and penetrates the
dura (2nd resistance) and subarachnoid membrane as signaled by free-
flowing CSF.

Paramedian( lateral approach):
 After identifying the proper interspace palpate the spinous process
 Insert needle 1cm lateral and 1 cm inferior to this point and direct needle
towards interspace
 May need to walk medially off of
transverse process
 Ligamentum flavum is usually the
first resistance identified

Taylors approach:
 Largest interspace L5-S1.
 posterior-superior spine:1cm medially and 1cm below.
 A 12-cm , needle is directed upward , medially and forward at an angle of about
50degree.
 The needle then is advanced so that it’s point enters the lumbosacral space between
the sacrum and the last lumbar vertebra.
 As the space is entered , there usually an immediate flow of CSF , although gentle
aspiration may be necessary.

Taylors approach:

Assessment of spinal anesthesia block
Autonomic(sympathetic nerve) block:
 Cardiovascular changes: Hypotension,..
 Colour and temperature changes in the
affected area.

Assessment of spinal anesthesia block
Sensory block:
 Pinprick and cold are most commonly used, but mechanical
stimuli such as touch, skin pinch, and pressure can be used.
 Generally, loss of sensation to cold occurs before pinprick,
and both of these before touch,
 Thus, temperature perception is lost before pinprick, is
generally at a higher level.

Motor block:
 As a block extends cephalad, there is
progressive impairment of motor as well as
sensory function. The commonest method of
assessment is the modified ‘Bromage scale’.

Factors which affects the height of local
anesthetic spread
CHARACTERISTICS OF THE INJECTED
SOLUTION:
 Baricity
 Volume / Dose/ Concentration

CLINICAL TECHNIQUE:
 Patient position
 Level of injection
 Needle type / Alignment
 Intrathecal catheters

PATIENT CHARACTERISTICS:
 Age
 CSF volume
 Pregnancy
 Height?
 Weight
 Sex
 Intra-abdominal pressure
 Spinal anatomy

Practical Problems
The spinal needle feels as if it is in the right position but no CSF
flows:
 Wait at least 30 seconds, then try rotating the needle 90 degrees and
wait again.
 If there is still no CSF, attach an empty 2ml syringe and inject 0.5-1ml
of air to ensure the needle is not blocked then use the syringe to
aspirate whilst slowly withdrawing the spinal needle.
 Stop as soon as CSF appears in the syringe.

Blood flows from the spinal needle:
 Wait a short time.
 If the blood becomes pinkish and finally clear, all is
well.
 If blood only continues to drip, it should be advanced a
little further or angled more medially to pierce the dura.

The patient complains of sharp, stabbing leg pain:
 Withdraw the needle and redirect it more medially away from
the affected side.
If bone is touched?
 Make sure the patient is still properly positioned
 if the patient is elderly and cannot bend very much or has
heavily calcified interspinous ligaments, attempt a lateral
approach to the dura.

Problems with the Block
No apparent block at all:
 After 10 minutes the patient still has full power in the legs and
normal sensation.
 Try again.
The block is one-sided or is not high enough on one side:
 Moving a patient around in any way at all in the first 10-20
minutes following injection will tend to increase the height of
the block.

Block not high enough:
 When using a hyperbaric solution, tilt the
patient head down whilst they are supine.
Block too high

Complications of spinal anesthesia
 Adverse or exaggerated
physiological responses
 Urinary retention
 High & Total spinal anesthesia
 Cardiac arrest
 Anterior spinal artery syndrome
 Horner's syndrome
 Nausea & vomiting
Complications related to
needle/catheter placement
 Trauma
 Backache
 Post dural puncture headache
 Neural & Spinal cord damage
 Cauda equina syndrome

 Bleeding &Intraspinal/epidural
hematoma
 No effect/inadequate anesthesia
 Inadvertent intravascular
injection
 Infection & Epidural absces
Drug toxicity :
 Systemic local
anesthetic toxicity
 Transient neurological
symptoms
 Cauda equina syndrome

?????????

Regional anesthesia1

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