neuroaxial anaesthesia

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NEURAXIAL ANAESTHESIA

• DR ISMAIL AHMED
• ANAESTHESIA CONSULTANT
• MD ANAESTHESIA AND INTESIVE CARE
• AL AZHAR UNIVERSTY

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Introduction

• Neuraxial anesthesia is a type of regional
  anesthesia that involves injection of anesthetic
  medication in the fatty tissue that surround the
  nerve roots or into the cerebrospinal fluid which
  surrounds the spinal cord
• Spinal anaesthesia
• 1898 - August Bier - first planned spinal
  anesthesia
• Epidural
• 1921- Fidel Pagés performed lumbar epidural
  anesthesia
• Caudal
• 1901- Cathelin use the technique of caudal
  epidural injection

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Outlines

• ? Anatomy
• ? Advantages
• ? Indications/ contraindications
• ? Physiologic effects
• ? Techniques
• ? Pharmacology
• ? Complications

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anatomy
There are 7 cervical, 12 thoracic and 5 lumbar
vertebrae. ? The sacrum is a fusion of 5 sacral
vertebrae. ? small rudimentary coccygeal vertebrae
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SPINAL CORD

• Spinal canal contains the spinal cord with the
  meninges-pia, arachnoid and dura mater Subdural
  and epidural spaces are potential spaces
• Extends from foramen magnum
• ? At birth, spinal cord ends at lower border of
  L3
• ? At 1 year- at L2
• ? gt12 years- at lower border of L1 (50)
• upper border of L2
  (40)
• body of T12 (5-6)
• upper border of L3
  (3)
• ? length- 45 cm (males) 42 cm (females)

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• Dural sac circular sac surrounding spinal cord
  Cranially attached to the circumference of
  foramen magnum Ends at S2 level( 35)
• LIGAMENTUM FLAVUM Yellow elastic tissue
• Between laminae of adjacent vertebrae Right
• and left halves fuse at midline

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DERMATOMES

• A dermatome is an area of skin innervated by
  sensory fibers from a
• single spinal nerve
• T4 nipples
• T6 xiphoid
• T10 umbilicus
• T12, L1 inguinal ligament , crest of ileum
• S2-S4 perineum
• Perineal and anal surgery S2 to S5 (saddle block)
• Upper abdominal surgery T4

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ADVANTAGES

• Cost effective ,Less risk of pulmonary
  aspiration , Avoid periop. respiratory
  complications,Less post-op. thromboembolism
  ,Avoid systemic effects of GA drugs
• CONTRAINDICATIONS

ABSOLUTE Relative
Patient refusal Uncooperative patient
Raised intracranial tension Previous spine surgery
Infection at local site Spine deformity
Severe hypovolaemic shock Spine metastasis
Coagulopathy Peripheral nerve disease
Valvular heart disease, SEVER STENOTIC Peripheral nerve disease MILD ,MODERTE
Patients on anticoagulants/ thrombolytics/ fibrinolytics Uncontrolled hypertension
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PHYSIOLOGICAL EFFECTS

• CVS
• Hypotension
• Bradycardia With high sympathetic block,
  sympathetic cardiac accelerator fibers arising at
  T1-T4 are blocked, leading to bradycardia
• CNS
• Sequence of blockage of nerve fibres Autonomic-gt
  Sensory -gt Motor
• Recovery in reverse order Autonomic level is 2
  segment higher than sensory which is 2 segment
  higher than motor - differential blockade
• Endocrine system
• Decrease stress response to surgery
• Gastrointestinal
• Contracted gut with sphincter relaxation
• Nausea/vomiting
• Genitourinary system
• Penile engorgement
• retention

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SPINAL ANAESTHESIA

• INDICATIONS
• ?Lower limb orthopaedic ,Abdominal surgeries
• ?Urological ,Obstetric and gynaecological
  procedure
• WHAT IS TUFFIERS LINE?
• A line drawn between the highest points of both
  iliac
• crests will correspond to either the body of L4
  or
• the L4-L5 interspace.

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SPINAL NEEDLES

• Quincke Babcock needle
• Whitacre needle
• Sprotte needle
• Greene needle

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PROCEDURE

• Preparation of the patient, consent,Pre-medication
  ,Anxiolytics, Monitors
• Intravenous line pre/co-loading with fluids,
  Maintainstrictasepsis
• POSITIONS
• Lateral flexed position
• Sitting position
• TECHNIQUE
• Midline approach
• Skin
• Subcutaneous tissue
• Supraspinous ligament
• Interspinous ligament
• Ligamentum flavum
• Dura mater
• Sub dural space
• Arachnoid mater
• Subarachnoid space

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• Paramedian approach
• 2 cm lateral to inferior aspect of superior
  spinous process
• advanced towards midline at 10-25 angulation
• Needle lies lateral to supraspinous and
  interspinous
• ligaments and penetrates ligamentum flavum
• and dura mater in the midline

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ASSESSMENT OF LEVELS OF BLOCK

• ? Sensory level
• Pin prick using sterile needle
• Temperature sensation
• Motor block
• ? Modified Bromage scale

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FACTORS AFFECTING SPREAD OF LA INSUBARACHNOID
SPACE
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EPIDURAL ANAESTHESIA

• INDICATIONS
• ? Intra/post operative analgesia
• ? Thoracic/ abdominal surgeries with or without
  GA
• ? With spinal anaesthesia for prolong surgeries
• ? Painless labour
• ? Chronic pain management
• ADVANTAGES
• ? Less hypotension
• ? No post spinal headache
• ? Level of block can be changed
• ? Duration of surgery can be prolonged

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EPIDURAL SPACE ( EXTRADURAL OR PERIDURAL SPACE)
It lies outside duramater. Extends from foramen
magnum to sacral hiatus CONTENTS OF EPIDURAL
SPACE ? Anterior and posterior nerve root ?
Epidural veins (Batson venous plexus) ? Spinal
arteries ? Lymphatics ? Fat
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Epidural needles

• ? Most common is Tuohys needle It is blunt bevel
  with curve of 15 to 30 degree at tip (Huber
  Tip) Blunt tip reduce the risk of accidental
  dural puncture and guide the catheter cephalad.
• ? Weiss is winged
• ? Crawford straight blunt bevel with no curve
• ? The catheter is made of a flexible, calibrated,
  durable, radiopaque plastic with either a single
  orifice or multiple side orifices near the tip

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EPIDURAL TECHNIQUES

• Patient preparation,Explain to the
  patient,Consent taking
• monitoring and resuscitation equipment,
  intravenous access
• Strict asepsis , Sterile drape
• Patient position-sitting or lateral
• Site of needle insertion depends on the extent of
  surgical field
• TECHNIQUES TO IDENTIFY EPIDURAL SPACE
• ? Loss of resistance technique after piercing
  ligamentum flavum there is loss of resistance.
• ? Hanging drop technique ( Gutierrezs sign)-
  drop of saline in hub sucked in due to negative
  pressure .
• ? MacIntosh extradural space indicator
• ? Odoms manometer indicator
• Epidural catheter is passed through the needle
  and 3 to 4 cm of catheter should be in epidural
  space.

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Test dose

• ?A test dose is designed to detect both
  subarachnoid and intravascular injection .
• ? The classic test dose combines local anesthetic
  and epinephrine, typically 3 mL of 2 lignocaine
  with 1200,000 epinephrine (0.005mg/mL).
• ? Lignocaine, if injected intra-thecal, will
  produce spinal anesthesia that should be rapidly
  apparent paresthesia
• ? Epinephrine, if injected intra-vascular, should
  produce a noticeable increase in heart rate (20
  or more), with or without hypertension

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CAUDAL ANAESTHESIA

• INDICATIONS
• Lower limb/ abdominal surgeries along with GA or
  sedation
• in paediatric patients Intra/ post op. analgesia
• The caudal space
• is the sacral portion of the epidural space.
• Caudal anesthesia
• needle and/or catheter penetration of the
  sacrococcygeal ligament covering the sacral
  hiatus. The sacral hiatus is a defect in the
  lower part of the posterior wall of the sacrum
  formed by the failure of the laminae of S5 and/or
  S4 to meet and fuse in the midline. The hiatus
  may be felt as a groove or notch above the coccyx
  and between two bony prominences, the sacral
  cornua .

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Contents of the Sacral canal

• Dural sac which ends at the border of the 2nd
  sacral vertebra on a line joining the posterior
  iliac spine.
• The pia mater is continued as the filum
  terminale.
• Sacral nerves and the coccygeal nerve.
• Venous plexus formed by the lower end of the
  internal vertebral plexus.
• Areolar and fatty tissue
• The posterior superior iliac spines
• and the sacral hiatus define an equilateral
  triangle

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TECHNIQUE

• The patient is placed in the lateral or prone
  position with one or both hips flexed and the
  sacral hiatus is palpated.
• After sterile skin,preparation, a needle
  intravenous cannula (1823gauge) is advanced at a
  45 angle cephalad until a pop is felt as the
  needle pierces the sacrococcygeal ligament,The
  angle of the needle is then flattened and
• advanced 1-2 cm
• Aspiration for blood and CSF is performed, and,
  if negative, LA is injected. For continuous
  caudal block, a catheter can be placed.

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• DRUGS USED FOR CAUDAL BLOCK
• ? volume
• 0.5ml/kg for lumbosacral block
• 1ml/kg for thoraco-lumbar block
• 1.25 ml//kg for midthoracic block
• ? Bupivacaine
• Maximum dose 2.5 mg/kg (without Adr) 3mg/kg
  (with Adr)
• 0.25 for analgesia and 0.5 for motor block
• ? Lignocaine
• Maximum dose 5mg/kg (without Adr) 7.5mg/kg
  (with Adr)
• 1 for analgesia and 2 for motor block

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• THANK YOU