Central neuroaxial anaesthesia

• Neuraxial anaesthesia involves

  Injection of anaesthetic medication in the fatty tissue that surrounds the nerve roots as they exit the spine (epidural) or into the cerebrospinal fluid which surrounds the spinal cord (spinal)
• Neuraxial anaesthesia numbs the patient from the abdomen to the toes and often eliminates the need for general anaesthesia
• J Leonard Corning administered the first spinal anaesthetic (most likely epidural) accidentally by injecting 120mg of cocaine between T11 and T12 spinous process


  1885
• Heinrich I. Quincke observed that the Dural sac could be punctured by inserting a needle between lumbar spinous processes


  1891
• August Bier planned the first spinal anaesthesia for Surgery using the Quincke method and injected between 5-15mg of cocaine to produce spinal anaesthesia in six patients


  1898
• Spanish military surgeon Fidel Pages developed the modern technique of lumbar epidural anaesthesia


  1921
• Robert Andrew Hingson developed the technique of continuous caudal anaesthesia together with Waldo Edwards
• Advantages of Regional Anaesthesia over GA

  • Safe, reliable technique in patients at risk of apnoea, bradycardia, desaturation, cardiac or respiratory complications after GA
  • Good alternative for day care surgeries
  • Minimal risk of postoperative respiratory depression
  • Limited stress response to surgery
  • Cost effective
• 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
• Contraindications - Relative

  • Sepsis
  • Uncooperative patient
  • Preexisting Neurological Deficit
  • Severe Spinal Deformity
• Patient Positioning

  1. Sitting Position

  2. Lateral Decubitus
• Anatomic Approach

  1. Midline Approach: Skin, Subcutaneous tissue, Supraspinous ligament, Interspinous ligament, Epidural space, Dura matter, Arachnoid matter

  2. Paramedian or Lateral Approach: Same as midline excluding supraspinous and interspinous ligaments
• Factors affecting level of spinal anaesthesia

  • Baricity of drug
  • Position of patient
  • Dose
  • Site
  • Age
  • Curvature of spine
  • Patient height
  • Pregnancy
• Drugs for spinal anaesthesia

  • Procaine
  • Lidocaine
  • Mepivacaine
  • Tetracaine
  • Ropivacaine
  • Levobupivacaine
  • Bupivacaine
• These drugs provide spinal anaesthetics that range from 45 to 400 minutes and offer two clinical lengths of action: shorter (<90 minutes) and longer (>90 minutes)
• Types of drugs for spinal anaesthesia

  • Procaine
  • Lidocaine
  • Mepivacaine
  • Tetracaine
  • Ropivacaine
  • Levobupivacaine
  • Bupivacaine
• Drugs for spinal anaesthesia

  • Provide anaesthetics that range from 45 to 400 minutes
  • Offer two clinical lengths of action: shorter (<90 minutes) and longer (> 90 minutes)
• Complications of Spinal Anaesthesia

  • Hypotension
  • Bradycardia
  • Cardiac Arrest
  • Total Spinal Anaesthesia
  • Urinary retention
  • High neural blockade
  • Neurological Complications- cauda equina Syndrome
  • Inadequate anaesthesia or analgesia
  • Post Dural Puncture Headache
  • Infection
  • Backache
  • Inflammatory reaction due to tissue trauma
  • May result in back spasms
  • May last a few weeks
  • Backache may be a sign of serious complications such as epidural/spinal haematoma, abscess
  • Careful evaluation to determine if a common/benign complication or something more serious
• Cause of Postdural Puncture Headache

  1. Disrupting the integrity of the dura

  2. Can occur due to: spinal anaesthesia, “wet” tap with epidural, epidural catheter migrating, tip of the epidural “indenting” the dura enough to cause a leak
• Symptoms of Postdural Puncture Headache

  • Onset is generally within 12-72 hours
  • Headache associated with upright position (i.e. sitting or standing). Relief found with a supine position
  • Headache may be bilateral, frontal, retroorbital and/or occipital with or without radiation to the neck
  • Described as “throbbing” or constant
  • May be associated with photophobia
  • Traction on the 6th cranial nerve can result in diplopia and tinnitus
• Conservative Treatment for Postdural Puncture Headache

  1. Hydration – theoretically helps to encourage the production of CSF

  2. Analgesics- will decrease the severity of symptoms and include acetaminophen and NSAIDS

  3. Caffeine – Helps to decrease symptoms by vasoconstriction of the cerebral vessels

  4. A dose of 300mg of oral caffeine has been shown to decrease the intensity of PDPH

  5. Epidural blood patch
• Epidural Blood Patch

  1. 90% or more effective in the treatment of postdural puncture headache

  2. Involves injecting 15-20 mL of autologous blood into the epidural space at, or one interspace below, the level of the dural puncture

  3. Believed to stop further leakage of CSF by either mass effect or coagulation
• Epidural Space


  • Space that surrounds the spinal meninges
  • Potential space
  • Ligamentum flavum binds epidural space posteriorly
  • Widest at level L2 (5-6mm)
  • Narrowest at level C5 (1-1.5mm)
• Epidural Anatomy

  • Safest point of entry is midline lumbar
  • Spread of epidural anaesthesia parallels spinal anaesthesia
  • Nerve rootlets
  • Nerve roots
  • Spinal cord
• Order of Blockade in Epidural Anaesthesia

  1. B fibers

  2. C & A delta fibers

  3. Pain

  4. Temperature

  5. Proprioception

  6. A gamma fibers

  7. A beta fibers

  8. A alpha fibers
• Test Dose in Epidural Anaesthesia

  1. 1.5% Lido with Epi 1:200,000

  2. Tachycardia (increase >30bpm over resting HR)

  3. High BP

  4. Light headedness

  5. Metallic taste in the mouth

  6. Facial numbness

  7. Note if beta blocked will only see increase in BP and not HR

  8. Bolus Dose 10 ml for labor pain

  9. 20-30 ml for C-section
• Distances from skin to Epidural space

  1. Average adult: 4-6cm

  2. Obese adult: up to 8cm

  3. Thin adult: 3cm

  4. Assessment of sensory Blockade

  5. Alcohol swab

  6. Most sensitive initial indicator to assess loss of temperature

  7. Pin prick

  8. Most accurate assessment of overall sensory block
• Bolus Dose for labor pain


  • 10 ml
• Bolus Dose for C-section

  • 20-30 ml
• Epidural Anaesthesia


  • Distances from skin to Epidural space: Average adult: 4-6cm, Obese adult: up to 8cm, Thin adult: 3cm
  • Assessment of sensory Blockade: Alcohol swab (Most sensitive initial indicator to assess loss of temperature), Pin prick (Most accurate assessment of overall sensory block)
• Complications of Epidural Anaesthesia

  • Penetration of blood vessels, Hypotension (nausea & vomiting), Intravascular catheterization, Wet tap, Infection
• Differences between Spinal and Epidural Anaesthesia

  • Spinal: Level below L1/L2 where the spinal cord ends, Injection subarachnoid space i.e puncture of the dura mater, Identification of subarachnoid space when CSF appears
  • Epidural: Level at any level of the vertebral column, Injection epidural space (between Ligamentum flavum and the dural mater) i.e without puncture of the dura mater, Identification of the Peridural space using the loss of resistance technique
• Differences between Spinal and Epidural Anaesthesia

  • Spinal: Doses 2.5-3.5 ml heavy bupivacaine 0.5%, Onset of action rapid (2-5 min), Density of block more dense, Hypotension rapid, Headache is a probable complication
  • Epidural: Doses 15-16 ml bupivacaine 0.5%, Onset of action slow (15-20 min), Density of block less dense, Hypotension slow, Headache is not a probable complication
• Caudal Anaesthesia


  • Block of the sacral and lumbar nerve roots, Technique popular in paediatric patients, Indications: Surgical procedure below the umbilicus, As an adjuvant to GA, Sole anaesthetic technique in fully awake ex-premature infants younger than 60 wk of post conceptual age, Contraindications: Major malformations of sacrum (myelomeningocele, open spina bifida), Meningitis, Intracranial hypertension
• Caudal Doses

  • Peadiatric: 0.5mg/kg, 0.25% bupivacaine (sacro-lumbar block), 1mg/kg, 0.25% bupivacaine (upper abdominal block), 1.2mg/kg, 0.25% bupivacaine (mid thoracic block) (doses described by Armitage), Adults: 20-20 ml 0.25-0.5% bupivacaine, Average volume of the sacral canal is 30-35ml
• Caudal Anaesthesia Anatomy

  • Sacrum: Triangular bone, 5 fused sacral vertebrae, Needle insertion: Sacrococcygeal membrane, No subcutaneous bulge or crepitous at site of injection after 2-3ml
• Caudal Anaesthesia Post operative problems

  • Pain at injection site is most common, Slight risk of neurological complications, Risk of infection
• Complications of Local Anaesthetics

  • Hypotension, Motor block, Urinary retention, Catheter epidural hematoma, Infection, Opioids respiratory depression, Urinary retention, Pruritus, Nausea
• Combined Spinal Epidural (CSE)


  • CSE technique combines the rapid, reliable onset of profound analgesia resulting from intrathecal injection along with the flexibility and longer duration of analgesia/anaesthesia due to epidural administration of the LA. Moreover, for cesarean sections, the same catheter can be used for providing anaesthesia
• Methods Used to perform a CSE block

  Epidural catheter insertion followed by spinal needle placement at a lower interspace, Epidural needle is inserted beside the spinal needle at the same interspace, In the most commonly used “needle-through-needle” technique, epidural space is identified with an epid