conduct of regional anaesthesia

1. CONDUCT OF REGIONAL
ANAESTHESIA
Dr.Charulatha.R MD
Assistant Professor
MGMCRI

2. August Bier 1885

4. SPINAL CORD

5. Flow of CSF

6. Where Spinal Cord Ends

8. Cauda Equina

10. BLOOD SUPPLY TO SPINAL
CORD

11. 100% Sterile

12. Spinal Anaesthesia

13. Holding for Spinal

14. Sitting Position

15. Flexion

16. Structures
Pierced

17. Spinal Needle

18. Factors Influence The Level Of
Anaesthesia
 The level of Injection
 The volume of drug
 Tilt of Table
 Speed of Injection

19. Advantages of spinal anaesthesia
• Full and complete anaesthesia
• Prolonged block: Pain free postoperatively
• Alternative to GA for certain poor risk patients esp.:
- Difficult airway
- Respiratory disease
• Contracted bowel
• Good muscle relaxation
• Suitable for certain surgical procedures:
-

20. Caesarian section (awake patient, bonding)
-Lower limb surgery
-Lower abdominal surgery
- Urological & gyneacological procedures.

21. SITTING / LYING

22. Reason For the Patho
physiological Changes
 Blockade of the Sympathetic
Systems

23. Cardivascular Changes
 Hypotension
 Tachycardia
 Bradycardia
 Sympathetic
Blockade
 Marys law/Mayos
Reflex
 Bainbridge Reflex

24. Drug for Spinal Anaesthesia
 Lignocaine
 Bupivacaine
 Hyperbaric
Stay in the lowest
area as pergravity
 5% with Glucose
 0.5% with Glucose
 Does not mix up
with CSF

25. Complications
 On Table
 Delayed

26. On Table Complication
 Hypotension  IV Isotonic Fluids
 Vasopressors
 Oxygen by mask
 Atropine-
Bradycardia

27. Pregnancy & Spinal
 Aortocaval
Occlusion
 Pre loading with IV
Fluids
 Left lateral Position
 Vasopressors
 Oxygen therapy

28. Delayed Complication
 Head ache
 Sixth Cranial nerve
palsy
 Infection

29. How to prevent Delayed
Complication
 UseThinSpinal needles
 SterilePrecaution

30. Indication
 Economical
 Pulmonary Diseases
 Full Stomach
 Lower Abdominal Surgery
 Ischemic Heart Diseases for Lower Abdominal
Surgery

31. Relative Contraindication
 Hypotensive Patients
 Cardiac failure
 Raised ICT
 Spinal Deformity
 Refusing Patients
 Bleeding Diathesis
 Skin Infection

32. Introduction to Epidural
Anesthesia
 Epidural anesthesia produces a reversible loss
of sensation and motor function much like a
spinal with the exception that local anesthetic
is placed within the epidural space.
 Larger doses of local anesthetic are required
to produce anesthesia when compared to a
spinal anesthetic.
 Doses must be monitored to avoid toxicity.

33. Introduction to Epidural Anesthesia
 An epidural catheter allows the versatility to
extend the duration of anesthesia beyond the
original dose by the administration of
additional local anesthetic.
 Epidural catheters may be left in place for
postoperative analgesia.

34. Epidural Anesthesia Indications
 Cesarean section
 Procedures of the uterus, perineum*
 Hernia repairs
 Genitourinary procedures
 Lower extremity orthopedic procedures
 Excellent choice for elderly or those who may
not tolerate a general anesthetic

35. Epidural Anesthesia
 Should NOT be used in patients who are
hypovolemic or severely dehydrated.
 Patients should be pre-hydrated with .5 – 1
liter of crystalloid solutions (i.e. ringers lactate)
immediately prior to the block.

36. Epidural Anesthesia
 Higher failure rate for procedures of the
perineum.
 Lower lumbar and sacral nerve roots are large
and there is an increased amount of epidural
fat which may affect local anesthetic
penetration and blockade.
 This is known as sacral sparing.

37. Epidural Anesthesia Advantages
 Easy to perform (though it takes a bit more
practice than spinal anesthesia)
 Reliable form of anesthesia
 Provides excellent operating conditions
 The ability to administer additional local
anesthetics increasing duration
 The ability to use the epidural catheter for
postoperative analgesia

38. Epidural Anesthesia Advantages
 Return of gastrointestinal function generally
occurs faster than with general anesthesia
 Patent airway
 Fewer pulmonary complications compared to
general anesthesia
 Decreased incidence of deep vein thrombosis
and pulmonary emboli formation compared to
general anesthesia

39. Epidural Anesthesia Disadvantages
 Risk of block failure. The rate of failure is
slightly higher than with a spinal anesthetic.
Always be prepared to induce general
anesthesia if block failure occurs.
 Onset is slower than with spinal anesthesia.
May not be a good technique if the surgeon is
impatient or there is little time to properly
perform the procedure.

40. Epidural Anesthesia Disadvantages
 Normal alteration in the patient’s blood pressure and
potentially heart rate (generally slower onset with less
alteration in blood pressure and heart rate than with a
spinal anesthetic). It is essential to place the epidural
block in the operating room/preoperative area with
monitoring of an ECG, blood pressure, and pulse
oximetry. Resuscitation medications/equipment should
be available.
 Risk of complications as outlined in Introduction to
Neuraxial Blockade chapter. There is an increase in the
complication rate compared to spinal anesthesia.

41. Epidural Anesthesia Disadvantages
 Continuous epidural catheters should not be
used on the ward if the patient’s vital signs are
NOT closely monitored.
 Risk for infection, resulting in serious
complications.

42. Absolute Contraindications Epidural
 Patient refusal
 Infection at the site of injection
 Coagulopathy
 Severe hypovolemia
 Increased Intracranial pressure
 Severe Aortic Stenosis
 Severe Mitral Stenosis
 Ischemic Hypertrophic Sub-aortic Stenosis

43. Relative Contraindications
 Sepsis
 Uncooperative patients
 Pre-existing neuro deficits/neurological deficits
 Demylenating lesions
 Stenotic valuvular heart lesions (mild to
moderate Aortic Stenosis/Ischemic
Hypertrophic Sub-aortic Stenosis)
 Severe spinal deformities

44. Controversial
 Prior back surgery
 Inability to communicate with the patient
 Complicated surgeries that may involved
prolonged periods of time to perform, major
blood loss, maneuvers that may complicate
respiration

45. Mechanism/Site of Action
 Administered at a physiologic distance when
compared to spinal anesthesia. The intended
targets are the spinal nerves and associated
nerve roots.
 Several barriers to the spread of local
anesthetic to the intended site of action results
in the requirement of larger volumes of local
anesthetic when compared to spinal
anesthesia.

46. Barriers
 Dura mater between the epidural space and
spinal nerve and nerve roots act as a modest
barrier.
 The majority of the solutions is absorbed
systemically through the venous rich epidural
space.
 Epidural fatty tissue acts as a reservoir.
 The remainder reaches the spinal nerve and
nerve roots.

47. Spread of Local Anesthetic in the
Epidural Space
 Local anesthetic injected into the epidural
space moves in a horizontal and longitudinal
manner.
 Theoretically the longitudinal spread could
reach the foramen magnum and sacral
foramina if enough volume was injected.

48. Spread of Local Anesthetics- Longitudinal

49. Spread of Local Anesthetics-
Horizontal
 Horizontally the local anesthetic spreads
through the intervertebral foramina to the dural
cuff.
 Local anesthetics spread through the dural
cuff via the arachnoid villa and into the CSF.
 Blockade occurs at the mixed spinal nerves,
dorsal root ganglia, and to a small extent the
spinal cord.

50. Spread of Local Anesthetics- Horizontal

51.  Spread of Local Anesthetics- Local
anesthetics gain access to CSF via
arachnoid granules

52. Distribution, Uptake & Elimination
 Takes 6-8 times the dose of a spinal
anesthetic to create a comparable block.

53. This is due to:
 Larger mixed nerves are found in the epidural
space when compared to the subarachnoid
space.
 Local anesthetics must penetrate arachnoid and
dura mater.
 Local anesthetics are lipid soluble and will be
absorbed by tissue and epidural fat.
 Epidural veins absorb a significant amount of
local anesthetic with blood concentrations
peaking in 10-30 minutes after a bolus.

54. Distribution, Uptake & Elimination
 Local anesthetics absorbed in the epidural
veins will be diluted in the blood.
 The pulmonary systems acts as a temporary
buffer and protects other organs from the toxic
effects of local anesthetics.
 Distribution occurs to the vessel rich organs,
muscle, and fat.

55. Distribution, Uptake & Elimination
 Long acting amides will bind to alpha-1
globulins which have a high affinity to local
anesthetics but become rapidly saturated.
 Amides are metabolized in the liver and
excreted by the kidneys.
 Esters are metabolized by
pseudocholinesterase so rapidly that there are
rarely significant plasma levels.

56. Factors Affecting Height of Epidural
Blockade
 Volume of local anesthetic
 Age
 Height of the patient
 Gravity

57. Volume
 Can be variable
 General rule: 1-2 ml of local anesthetic per
dermatome
 i.e. epidural placed at L4-L5; you want a T4
block for a C-sec. You have 4 lumbar
dermatomes and 8 thoracic dermatomes. 12
dermatomes X 1-2 ml = 12-24 ml
 Big range! Stresses importance of
incremental dosing!

58. Volume
 If you require only segmental anesthesia than
the dose would be less.
 Volume of local anesthetic plays a critical role
in block height.
 Dose of local anesthetics administered in
thoracic area should be decreased by 30-50%
due to decrease in compliance and volume.

59. Age
 As age increases the amount of local
anesthetic to achieve the same level of
anesthesia decreases. A 20 year old vs 80
year old
 This is due to changes in size and compliance
of the epidural space

60. Height
 The shorter the patient the less local
anesthetic required.
 A patient that is only 5’3” may require 1 ml per
dermatome while someone who is 6’3” may
require the full 2 ml per dermatome

61. Gravity
 Position of patient does affect spread and height
of local anesthetic BUT not to the point of spinal
anesthesia.
 i.e. lateral decubitus position will “concentrate”
more local anesthetic to the dependent side will
a weaker block will occur in the non-dependent
area.
 A sitting patient will have more local anesthetic
delivered to the lower lumbar and sacral
dermatomes

62. Gravity
 L5-S2 sometimes will have ‘patchy’ anesthesia
due to sparing. By having the patient “sitting”
or in a semifowlers position one can
concentrate local anesthetic to this area.
 Trendelenberg or reverse trendelenberg may
help spread local anesthetic cephalad or
alternatively limit the spread.

63. Local Anesthetics used for Epidural
Anesthesia

64. Considerations in choosing
 Understanding of local anesthetic potency &
duration
 Surgical requirements and duration of surgery
 Postoperative analgesic requirements

65. Local Anesthetics for Epidural
Anesthesia
 Use only preservative free solutions
 Read the labels, ensure that it is preservative
free or prepared for epidural/caudal
anesthesia/analgesia

66. Categories according to duration of
action
 Short Acting: 2-chloroprocaine
 Intermediate Acting: lidocaine and
mepivacaine
 Long Acting: bupivacaine, etidocaine,
ropivacaine, levobupivacaine

67. Intermediate Acting Lidocaine
 Prototypical amide local anesthetic
 1.5-2% concentrations used for surgical
anesthesia
 Epinephrine will prolong the duration of action
by 50%
 Addition of fentanyl will accelerate the onset of
analgesia and create a more potent/complete
block

68. Intermediate Acting Lidocaine

69. Lignocaine
 Dose 3mg /kg
 7mg/kg with adrenaline
 Prolong action/reduces the toxicity

70. Long Acting Bupivacaine
 Long acting amide local anesthetic
 0.5-0.75% concentrations used for surgical
anesthesia
 0.125-.25% used for epidural analgesia
 Epinephrine will prolong duration of action but
not to the extent of lidocaine, mepivacaine,
and 2-chloroprocaine

71. Long Acting Bupivacaine
 0.75% concentration should not be used in OB
 In 1983 the FDA came out with this
recommendation
 There were several cardiac arrests due to
inadvertent intravascular injection in OB patients
 Bupivacaine (as well as etidocaine) are more
likely to impair the myocardium and conduction
system with toxic doses than other local
anesthetics

72. Long Acting Bupivacaine
 Bupivacaine has a high degree of protein
binding and lipid solubility which accumulate in
the cardiac conduction system and results in
the advent of refractory reentrant arrhythmias

73. Long Acting Bupivacaine

74. Bupivacaine
 Longacting 4-6 hours
 Deferential blockers
-Sensory more than Motor
-Dose- 1-1.5 mg/kg
-Cardiac Toxic
-No Tachyphylaxis- Repeat drug

75. Long Acting Levobupivacaine
 S isomer of bupivacaine
 Used in the same concentrations
 Clinically acts just like bupivacaine with the
exception that it is less cardiac toxic

76. Long Acting Levobupivacaine

77. Long Acting Ropivacaine
 Long acting amide local anesthetic
 Mepivacaine analogue
 Used in concentrations of 0.5-1% for surgical
anesthetic
 Used in concentrations of 0.1-0.3% for
analgesia
 Ropivacaine is unique among local
anesthetics since it exhibits a vasoconstrictive
effect at clinically relevant doses

78. Long Acting Ropivacaine
 Similar to bupivacaine in onset, duration, and
quality of anesthesia
 Key differences include: in doses for analgesia
there is excellent sensory blockade with low
motor blockade and it is less cardiotoxic than
bupivacaine

79. Long Acting Ropivacaine

80. Local anaesthetic systemic
toxicity
 Tingling sensation around mouth
 Drowsiness
 Hypotension
 seizures
Treatment
 ABC
 Midazolam /thiopentone
 intralipid

81. Epidural Additives
 Epinephrine will increase the duration of action
of all epidurally administered local anesthetics.
 There is a large variability among local
anesthetics as to the degree of increase
 The greatest effect is found with lidocaine,
mepivacaine, 2-chloroprocaine.
 Lesser effects found with bupivacaine,
levobupivacaine, etidocaine
 Minimal effects have been found with
ropivacaine

82. Epidural Additives
 Epi vs phenylephrine
 Epi is more effective in reducing peak blood
levels
 Phenylephrine does not appear to reduce the
peak blood levels

83. Epidural Additives
 Carbonation of local anesthetics has been
touted to improve the quality of epidural blocks
due to increased penetration of connective
tissue and intraneural diffusion
 Studies are ambivalent
 Carbonation may not improve quality or onset;
may lead to increased blood levels of local
anesthetic; result in a higher incidence of
hypotension when compared to non carbonated
local anesthetics

84. Epidural Additives
 Sodium bicarbonate can be added to
lidocaine, mepivacaine, and 2-chloroprocaine
 Addition will increase the amount of free base
which increases rate of diffusion and speeds
onset
 Studies have found that when added to 1.5%
lidocaine speeds onset of blockade and
results in a more solid block

85. Epidural Additives
 Generally 1 meq of bicarbonate is added to 10
ml of local anesthetic (i.e. lidocaine,
mepivacaine, 2-chloroprocaine)
 The addition of bicarbonate to bupivacaine is
not as popular. Usually 0.1 ml of bicarbonate
is added to 10 ml of bupivacaine
 Bupivacaine precipitates occurs at a pH > 6.8

86. Epidural Additives
 Mixing long acting and short acting local
anesthetics may not have much advantage for
epidural anesthesia
 Many choices for local anesthetics and
additives

87.  Thank you