Dr. Suhas presented on regional anesthesia techniques. The presentation covered spinal and epidural anatomy, techniques for administering spinal and epidural blocks, factors affecting the level and duration of blocks, potential complications and their treatment, and applications of regional techniques for different procedures. Key points included identifying spinal landmarks, administration procedures to avoid complications like high blocks, and managing issues like post-dural puncture headache.

1. DR. SUHAS. U
DEPARTMENT OF SURGERY
APOLLO HOSPITAL , MYSORE
A PRESENTATION ON
REGIONAL ANESTHESIA
BY

2. Regional Anesthesia

3. Objectives
◦ Anatomy of spinal canal
◦ Identify anatomic landmarks for proper placement of a
spinal needle
◦ Define appropriate steps for placement of spinal, epidural,
or caudal needle
◦ Distinguish level of anesthesia after administration of
regional
◦ State factors affecting level and duration of spinal vs.
epidural block
◦ Explain potential complications and corresponding
treatments associated with administration of regional
anesthetics

4. Spinal Anatomy
 33 Vertebrae
◦ 7 Cervical
◦ 12 Thoracic
◦ 5 Lumbar
◦ 5 Sacral
◦ 4 Coccygeal

5. Spinal Cord
GENERAL CONSIDERATIONS
– Adult
• Begins: Foramen Magnum
• Ends: L1
– Newborn
• Begins: Foramen Magnum
• Ends: L3
– Terminal End: Conus Medullaris
– Filum Terminale: Anchors in sacral region
– Cauda Equina: Nerve group of lower dural sac

6. Sagittal Sections (ANATOMY CONTD)
• Supraspinous Ligament
– Outer most layer
• Interspinous Ligament
– Middle layer
• Ligamentum Flavum
– Inner most layer
• Space that surrounds the spinal meninges
– Potential space(epidural)
• Widest at Level L2 (5-6mm)
• Narrowest at Level C5 (1-1.5mm)

7. Spinal Meninges
 Dura Mater
◦ Outer most layer
◦ Fibrous
 Arachnoid
◦ Middle layer
◦ Non-vascular
 Pia
◦ Inner most layer
◦ Highly vascular
 Sub Arachnoid Space
◦ Lies between the arachnoid
and piamater.

8. Spinal Technique
Preparation & Monitoring
◦ ECG
◦ NBP
◦ Pulse Oximeter
Patient Positioning
◦ Lateral decubitous
◦ Sitting
◦ Prone (hypobaric
technique)

9. Spinal APPROACHES
• Midline Approach
– Skin
– Subcutaneous tissue
– Supraspinous ligament
– Interspinous ligament
– Ligamentum flavum
– Epidural space
– Dura mater
– Arachnoid mater
• Paramedian or Lateral Approach
– Same as midline excluding supraspinous &
interspinous ligaments

10. Technique
• Palpate the spinous process
• Cervical and lumbar are horizontal
• Thoracic – slant in caudal
• Slight angled in lumbar
• Identification of the spine level
o C7- most prominent cervical spine
o T7-inferior angle of scapula
o L4- line joining iliac crest
o S2- PSIS
• Loss of resistance and flow of CSF

12. Mechanism of Action
• Un-ionized local
anesthetic diffuses
into nerve axon & the
ionized form binds the
receptors of the Na
channel in the
inactivated state.

13. Metabolism & Toxicity
• Metabolism
– Ester locals are metabolized by plasma
psuedocholinesterase
– Amide locals are metabolized by the liver
• Toxicity
– Determined by blood concentration of local anesthetics

14. Sequence of Loss of Nerve Function
with Local Anesthetics (LA)
• 1. Sympathetic (vasomotor): dilation of skin and blood
vessels including arteries and veins
• 2. Temperature discrimination & pain recognition
• 3. Touch and pressure sense
• 4. Proprioception (awareness of body position)
• 5. Motor function
Sympathetic block is 2-6 dermatomes higher than sensory block
Motor block is 2 dermatomes lower than sensory block

15. Factors Effecting Distribution
– Site of injection
– Shape of spinal column
– Patient height
– Angulation of needle
– Volume of CSF
– Characteristics of local anesthetic
• Density
• Specific gravity
• Baricity
– Dose
– Volume
– Patient position (during & after)

16. Local Anesthetics & Baricity
• Hyperbaric
– Typically prepared by mixing local with dextrose
– Flow is to most dependent area due to gravity
• Hypobaric
– Prepared by mixing local with sterile water
– Flow is to highest part of CSF column
• Isobaric
– Neutral flow that can be manipulated by positioning
– Very predictable spread
– Increased dose has more effect on duration than
dermatomal spread

17. • Most commonly used local anesthetic :
o Bupivacaine 0.5% and 0.25%
o Lignocaine 2% (transient neurological symptoms)
• Adjoints like opioids and adrenaline

18. Indications & Advantages
– Anatomic distortions of
upper airway
– Lower abdominaL
surgeries
– Obstetrical surgery (T4
Level)
– Decreased post-operative
pain
Contraindications
– Absolute:
• Refusal
• Infection
• Coagulopathy
• Severe hypovolemia
• Increased
intracranial pressure
• Severe aortic or
mitral stenosis
– Relative:
• Doctor’s judgment

19. SYSTEMIC EFFECTS
Cardiovascular Effects
• Blockade of Sympathetic Preganglionic Neurons
– Send signals to both arteries and veins
– Predominant action is venodilation
• Reduces:
– Venous return
– Stroke volume
– Cardiac output
– Blood pressure

20. – T1-T4 Blockade
• Causes unopposed vagal stimulation
Bradycardia
» Associated with decrease venous return & cardioaccelerator
fibers blockade
» Decreased venous return to right atrium causes decreased
stretch receptor response
• Treatment
– Best way to treat is physiologic not pharmacologic
– Primary Treatment
• Increase the cardiac preload
– Large IV fluid bolus within 30 minutes prior to spinal placement,
minimum 1 liter of crystalloids
– Secondary Treatment
• Pharmacologic
– Ephedrine is more effective than Phenylephrine

21. Respiratory System
• Healthy Patients
– Appropriate spinal blockade has little effect on
ventilation
• High Spinal
– Decrease functional residual capacity (FRC)
• Paralysis of abdominal muscles
• Intercostal muscle paralysis interferes with
coughing and clearing secretions
• Apnea is due to hypoperfusion of respiratory center

22. Different settings
• Oral coagulants – INR / prothrombin time
• Antiplatelet drugs- Ticlopidine(14days),
clopidogrel(7days) , Abciximab(48hrs),
Eptifibatide(8hrs)
• Unfractionated Heparin
o Minidose s.c heparin – not a contraindication
o Need for systemic heparin intraop- block to be given 1Hr
before
o Increased aPTT- avoid regional

23. COMPLICATIONS AND SURGICAL
RELAVENCE
• Exaggerated physiological response
• Associated with needle placement
• Associated with catheter placement
• Associated with medication toxicity

24. • Exaggerated Physiological Response Include
• High neural blockade
• Cardiac arrest
• Urinary retention
• High Neural Blockade Causes
• Excessive doses of local anesthetic are administered
• Failure to reduce dose in patients susceptible to excessive spread (i.e.
the elderly, pregnant, obese, or short patients)
• Unusual sensitivity
• Unusual excessive spread

25. High Neural Blockade – SYMPTOMS AND
MANAGEMENT
• Dyspnea
• Numbness and tingling of the upper extremities (i.e. fingers)
• Nausea generally preceedes hypotension due to hypoperfusion of the chemoreceptor trigger zone
• Mild to moderate hypotension
• TREATMENT
• Change position with hyperbaric technique(i.e. reverse
Trendelenberg)
• Stop the administration of local anesthetics with an epidural
technique
• Supplemental oxygen
• Liberal use of IV fluids
• Treat hypotension with ephedrine or phenylephrine
• Treat bradycardia

26. Urinary Retention
• Due to blockade of S2-S4
• Leads to a decrease in bladder tone and inhibition of normal voiding
reflex
• Neuraxial opioids may contribute to urinary retention
• More common in elderly men and those with a history of benign
prostatic hypertrophy
• Urinary catheterizes should be provided for patients undergoing
moderate to lengthy procedures
• Postoperative assessment is important to detect urinary retention
• Prolonged urinary retention may be a sign of serious neurological injury

27. Complications Associated with Needle
Placement or Catheter Insertion
• Inadequate anesthesia or analgesia
• Inadvertent intravascular injection
• Total spinal
• Subdural injection
• Backache
• Postdural puncture headache
• Neurological injury
• Spinal or epidural hematoma
• Meningitis and arachnoiditis
• Epidural abscess
• Sheering off the tip of the epidural catheter

28. • Inadequate Analgesia or Anesthesia- May be
associated with anatomical factors with epidural
more than spinal.
• Inadvertent Intravascular Injection
• Toxicity will affect the central nervous system and
cardiovascular system
• SYMPTOMS : Hypotension, Arrhythmias , Cardiovascular
collapse , Seizures, Unconsciousness.
Local Anesthetic Toxicity Treatment
i.V intralipoid solution

29. • SUBDURAL INJECTION
• Most commonly associated with epidural analgesia
• Larger doses of local anesthetics associated with epidural
anesthesia may result in a total spinal.
• BACK ACHE
• Back ache may be a sign of serious complications such as
epidural/spinal hematoma, abscess

30. Postdural Puncture Headache
• Headache occurs due to leakage of CSF through the dura
• Decrease in intracranial pressure occurs due to the leak
• Upright position in the patient leads to traction on the dura, tentorium,
and blood vessels resulting in pain.
• Traction on the 6th cranial nerve can result in diplopia and tinnitus
• 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 nausea and/or photophobia
• Onset is generally 12-72 hours; rarely is the onset immediate
• If untreated it may last for weeks
• Increased post dural puncture headache in younger patients, in female
patients, and in pregnant patients

31. Postdural Puncture Headache- Associations
• Increased incidence related to needle size, needle type
• The larger the needle the higher the incidence
• Cutting point needles have a higher incidence of post dural
puncture headache than pencil points
• When using cutting point needles orientate the bevel
“sideways” so it will be parallel with the fibers. This will act to
“spread” the fibers as opposed to cutting them
• A wet tap with a 17 g. epidural needle will yield a 50%
incidence of pdph

32. PDPH TREATMENT
• Supine position- will reduce symptoms, no evidence that bed rest will
reduce the duration of post dural puncture headache. Theoretically it
should decrease the amount of CSF leak and allow replacement of lost
CSF.
• Hydration- theoretically helps to encourage the production of CSF.
• Caffeine- theoretically helps to decrease symptoms by vasoconstriction
of the cerebral vessels. May decrease symptoms but does not
necessarily decrease the number of patients that will require an
epidural blood patch.
• IV caffeine can be administered in a dose of 500 mg
• Oral caffeine can be encouraged.
• Analgesics- will decrease the severity of symptoms and include
acetaminophen and NSAIDS
• Stool softners and soft diet may help decrease Valsalva straining which
may increase leakage of CSF

33. PDPH - Epidural Blood Patch
• Generally offered 12-24 hours after the initiation of conservative
treatment
• Check coagulation status
• Ensure no anticoagulants have been administered (i.e. DVT prophylaxis)
• Ensure that the patient is not bacteremic
• Should be administered one space below the dural puncture site
• Blood patch works by mass effect and stops the leakage of CSF or
alternatively by coagulating and “plugging” the hole
• Place 15-20 ml of blood into the epidural space
• Increased risk of meningitis or infection has to be explained to the
patient.
• PDPH is 90% effective and not absolutely curative.

34. Other Less encountered
complications
• Neurological Injury
• Spinal/Epidural Hematoma
• Meningitis
• Arachnoiditis
• Epidural Abscess
• Transient Neurological Symptoms
• Cauda Equina Syndrome
• Allergic Reactions

35. EPIDURAL
ANESTHESIA

36. • The epidural space is a potential space and is normally filled
with blood vessels, lymphatic vessels, fatty tissue and spinal
nerve roots.
• Epidural catheters in the epidural space do not pose a
mechanical threat to the spinal cord.
• Single bolus, or the catheter is left in place for ideally 2 to 5
days with a continuous infusion, depending on the surgery.

37. • There are two types of medications commonly administered via
the epidural route for surgical patients:
• 1. Opioid - usually, Fentanyl or Hydromorphone,
• 2. Local Anesthetics (LA) - usually Bupivicaine or Ropivicaine
• These are usually administered as combined (1 local anaesthetic
and 1 opioid solution) for continuous epidural infusions.
• The dose of spinal analgesia is only 1/10th of the dose used in the
epidural space.

38. CONTRAINDICATIONS FOR
EPIDURAL ANESTHESIA
Absolute
• Sensitivity to local anaesthetic
• Concurrent or recent anticoagulation
• Patient refusal
• Uncorrected hypovolemia
Relative (used with caution):
• Coagulation disorders
• Sepsis (local or generalized)
• Increased intracranial pressure
• Unstable spinal fractures
• Morbid obesity (difficulty with line placement)

39. Lumbar and Thoracic Epidurals
LUMBAR
• More likely to cause urinary
retention
• More likely to cause lower
extremity weakness/ motor
block
THORACIC
• Less likely to cause a lower
extremity motor block
• Less likely to cause urinary
retention:
• o Epidural T10 level or higher:
question the need for an
indwelling urinary catheter.
• o Evidence shows that the risk
for developing a UTI is much
higher for patients who have a
urinary catheter in for the
duration of the epidural
infusion compared to those
who have the urinary catheter
removed on Postoperative Day
1.

40. DISCONTINUING EPIDURAL THERAPY
If patient has received anticoagulation while an
epidural is insitu, DO NOT REMOVE epidural
catheter. Removal must be carefully coordinated
and often includes holding a dose and/or
administering Vitamin K and ensuring PTT/INR are
within normal limits prior to removal.
• If recent PTT/INR available ensure INR equal to
or below 1.2 and PTT less than 40. If elevated,
DO NOT REMOVE CATHETER.
• Remove epidural catheter 2 hours prior to next
dose of unfractionated subcutaneous heparin.

41. • If patient on once a day LMWH such as Dalteparin or
Enoxaparin, removal must be 12 hours after last dose(2 hours
prior to the next dose of Dalteparin or Enoxaparin).
• Assess black tip of catheter is smooth and round
• Apply band aid to site for 24 hours.
• COMPLICATIONS ARE SIMILAR TO SPINAL ANESTHESIA AS
MENTIONED EARLIER

42. Caudal Anaesthesia
• Pediatric patients
• Anorectal surgery in adults
• Sacral portion of epidural space
• Needle penetration of the sacrococcygeal
ligament covering sacral hiatus
• In children usually combined with GA

43. Procedure
• Lateral or prone position
• Both hips flexed and sacral hiatus palpated
• Needle advocated at 45 degree cephalad
• Pop felt – sacrococcygeal ligament pierced
• Angle is then flattened and advanced
• Bupivacaine with epinephrine with opiods

44. Uses
• Infants and children
o Surgery of perianal and rectal region
o Inguinal and femoral hernia
o Cystoscopy and urethral surgery
o Haemorrhoidectomy
• Evaluation of perianal , pelvic, perineal and lower
extremity pain
• For PAIN MANAGEMENT

45. Difficulties and problems
• Calcification of sacrococcygeal ligament
• Inadvertant intrathecal
• Total spinal and intravascular anaesthesia
• Avoided in patients with pilonidal cyst

46. BIBLIOGRAPHY
• MILLER TEXT BOOK OF ANESTHESIA – 8TH
EDITION
• OXFORD HANDBOOK OF ANESTHESIOLOGY
• CLINICAL ANESTHESIA – MORGAN AND
MIKHAIL
• BRITISH JOURNAL OF ANESTHESIOLOGY
• INTERNET