SPINAL ANAESTHESIA

1. Spinal Anaesthesia
Dr PARTHA PRATIM DEKA

2. History
• CSF Discovered – Domenico Catugno 1764
• CSF Circulation – F Magendie 1825
• First spinal analgesia - J Leonard Corning 1885
• First planned spinal analgesia – August Bier (16th
August 1898)

3. August Bier 1885

5. Indications
Surgeries of lower limbs, perineum,
pelvis, abdomen
It is ideal in
• Renal failure – onset is rapid, spread is
greater by two or three segments,
duration is shorter
• Cardiac disease
• Liver disease
• Obstetric anaesthesia

6. Indications
• Immunosuppressed patients – does not
impair cell mediated immunity
• Elderly patients
• Diabetes mellitus

7. Contra-indications
Absolute
• Patient refusal
• Infection at the site of injection
• Increased intracranial pressure
• Hypovolemia
• Shock – haemorrhagic, septic
• Septicemia
• Severe aortic and mitral stenosis
• Coagulopathies

8. Contra-indications
Relative
• Spinal cord and peripheral nerve diseases-
poliomyelitis, multiple sclerosis,
demyelinating diseases
• Brain tumors, CNS syphilis, meningitis
• Severe anemia
• Uncontrolled hypertension
• Valvular heart diseases
• Anticoagulant therapy

9. Contraindications
Relative
• Spinal congenital anomalies
• Acquired spinal anomalies
• Post-traumatic vertebral injuries
• Prior back surgery at the site of injection
• Metastatic lesions in the vertebral column
• Intestinal obstruction
• Obstructed hernia
• Mentally disturbed patients
• Uncooperative and apprehensive patients

10. Anatomy

11. Anatomy

12. Skin.
Subcutaneous fat
Supraspinous ligament.
Interspinous ligament.
Ligamentum flavum.
Epidural space.
Dura.
Subarachnoid space.
Anatomy

14. The spinal cord usually ends at the level of L1
in adults and L3 in children.
Dural puncture above these levels is
associated with a slight risk of damaging the
spinal cord and is best avoided.
An important landmark to remember is that a
line joining the top of the iliac crests is at
L4 to L4/5
Anatomy

15. Where Spinal Cord Ends

16. Cauda Equina

17. Surface anatomy
• Spinous processes
are palpable over the
spine and help define
the midline
• In cervical area
First palpable
spinous process is C2
Most prominent
spinous process is C7

18. Surface anatomy
• Spinous process of
T7 – inferior angle of
scapula
• Tuffier’s line –
body of
L4 or
L4-L5
interspace

19. Dermatomal levels
• T10 – umbilicus
• T6 – xiphoid
• T4 – nipples
• T12, L1 – inguinal
ligament , crest of
ileum
• S2-S4 – perineum

20. Procedure
• Preparation of the patient
• Pre-medication
Sedatives – benzodiazepines , opioids
To decrease acid secretions – H2
blockers, proton pump inhibitors
• Monitors
• Intravenous line – preloading with fluids

21. Positions
• Lateral flexed position
-most commonly used
-back parallel to edge
of table
-hips and knees
flexed, neck and
shoulder flexed
towards knees
-nose to knees

22. Positions
• Sitting position
-for saddle block
anaesthesia
-obese patients,
pregnant patients,
patients with
abnormal spinal
curvatures

23. Positions
• Sitting position
-patient should sit on
the table with knees
resting on the edge,
legs hanging over the
side and feet
supported by a stool
below

24. Positions
• Prone position
- suitable for
hypobaric techniques
-patient should be in
prone position with
OT table flexed under
his flanks, just above
the iliac crests

25. Technique
• Hands and lower forearms scrubbed for at
least 3 minutes
• Sterile gloves should be applied
• A large area of L-S spine from lower
border of scapula to iliac crests should be
painted using antiseptic solution
• Excess antiseptics removed after waiting
for sufficient time for the antiseptic to act

26. Technique
• Area is draped – view of T12 to S1 and
laterally of quadratus lumboram muscles
• Selection of space – tuffier’s line
• Raise a skin wheal with 2ml of 2%
lignocaine solution after negative
aspiration for blood

27. Technique
• Insert an introducer in the
midline
Uses -prevents deflection of
spinal needle
-fine gauge needles can
be used
-decreases incidence of
postpuncture headache
-decreases infections
-avoids skin fragments
from entering

28. Technique
• Spinal needle is inserted with the stylet
through the introducer
• Needle should be inserted in the midline
and directed cranially at an angle of less
than 50 degrees to the longitudinal axis of
the vertebral column
Bevel of the spinal needle should be kept
parallel to the longitudinal axis of the spine
Loss of resistances can be felt after
puncturing ligamentum flavum and the
duramater

29. Layers traversed by the spinal
needle (posterior to anterior)
• Skin
• Subcutaneous tissue
• Supraspinous
ligament
• Interspinous ligament
• Ligamentum flavum
• Duramater
• Sub dural space
• Arachnoidmater
• Subarachnoid space

30. Technique
• Remove stylet to observe free flow of CSF
• Attach 5 ml Luer Lok syringe containing
anaesthetic mixture to the spinal needle
• Stabilize the spinal needle and attach the
syringe by grasping the hub of spinal
needle with thumb and index finger while
propping the remaining fingers against the
patient’s back to provide support
(bromage grip)

31. Technique
• Inject at the rate of 0.2ml/sec
• Aspirate small amount of spinal fluid to
determine if the needle is still placed
properly
• Remove spinal needle and introducer
quickly and simultaneously

32. Technique
Paramedian approach
• 1.5 cm lateral to
midline
• Spinal needle is
inserted at an angle
of 25 degrees with the
midline and without
deviation cephalad or
caudad

33. Technique
Paramedian approach
• Needle lies lateral to supraspinous and
interspinous ligaments and penetrates
ligamentum flavum and duramater in the
midline
• Useful in arthritis , deformed spine

34. Taylor technique
• A 12 cm spinal needle
is inserted 1 cm
medially and 1 cm
above the lowest
prominence of
posterior superior iliac
spine
• Needle is directed
upwards medially and
forwards at an angle of
50 degrees

35. Technique
Taylor technique
Uses :
• Spinal fusion
• Arthritic spine
• Opisthotonus
• Skin infection in lumbar region

41. Spinal needles
Three parts
–Hub
–Canula
–Stylet
• Point of the canula is beveled and has a
sharp edge
• Lumenal sizes : 18 gauge to 30 gauge
• Length : 3.5 to 4 inches

42. Spinal needles
• Quincke Babcock needle

43. Spinal needles
• Whitacre needle

44. Spinal needles
• Sprotte needle

45. Spinal needles
• Pitkin needle

46. Spinal needles
• Touhy needle

47. Spinal needles
• Greene needle

48. Drugs used in spinal
anaesthesia
Lidocaine
• Rapid onset of action , intermediate
duration and low toxicity
• Disadvantages – Transient neurological
symptoms

49. Drugs used in spinal
anaesthesia
Bupivacaine
• Amide local anaesthetic
• Exhibits sensory/motor split
• Dose of 7.5mg – ambulatory surgery
• Low concentrations(0.1-0.125%) –
postoperative analgesia

50. Drugs used in spinal
anaesthesia
Ropivacaine
Compared to bupivacaine
• Longer onset of block to T10 (5 min vs 2
min)
• Lower median maximal block height ( T7 vs
T5)
• Shorter regression of sensory block to T10
(55 min vs 110 min)
• Quicker mobilization (253 min vs 331 min )
• Less CNS and cardiac toxicity

51. Drugs used in spinal
anaesthesia
Levobupivacaine
• Isolated (S) entantiomer of bupivacaine
• Similar to bupivacaine

52. Spinal anaesthetic agents
Drug preparation Perineum,
lower limbs
(mg) dose
Lower
abdomen
(mg)dose
Upper
abdomen
(mg)dose
Duration
(min)
procaine 10% solution 75 125 200 45
tetracaine 1% solution
in 10%
glucose
4-8 10-12 10-16 90-120
lidocaine 5% in 7.5%
glucose
25-50 50-75 75-100 60-75
bupivacaine 0.75% in
8.25%
dextrose
4-10 12-14 12-18 90-120
0.5% in 8%
dextrose
7.5 to 12.5 12.5-17.5 17.5-25 90-120
ropivacaine 0.2-1%
solution
8-12 12-16 16-18 90-120

53. • Local anaesthetic solution injected into the
subarachnoid space blocks conduction of impulses
along all nerves with which it comes in contact,
although some nerves are more easily blocked than
others.
• There are three classes of nerve: motor, sensory and
autonomic.
• Stimulation of the motor nerves causes muscles to
contract and when they are blocked, muscle paralysis
results.
Mechanism of action

54. Mechanism of action
• Sensory nerves transmit sensations such
as touch and pain to the spinal cord and
from there to the brain, whilst autonomic
nerves control the calibre of blood vessels,
heart rate, gut contraction.
• Generally, autonomic and sensory fibres
are blocked before motor fibres. This has
several important consequences.

55. Mechanism of action
• For example, vasodilation and a drop in blood
pressure may occur when the autonomic fibres
are blocked.
• Practical implications of physiological
changes. The patient should be well hydrated
before the local anaesthetic is injected and
should have an intravenous infusion in place so
that further fluids or vasoconstrictors can be
given if hypotension occurs.

56. Mechanism of action of local
anaesthetics on nerve conduction
• Interacts with the receptor situated within
the voltage sensitive sodium channel and
raises the threshold of channel opening
• Decreases the entry of sodium ions during
upstroke of action potential

57. Mechanism ……..
• Local depolarization fails to reach the
threshold potential and conduction block
ensues
• Onset time of blockade is related to the
pKa of the LA
• Lower pKa – fast acting

58. Adjuvants used
Opioids
• Addition of opioids improves analgesic
quality, prolongs sensory block, reduces
local anaesthetic requirements, reduces
duration of motor blockade and improves
haemodynamic stability
• Fentanyl – 12.5 mcg
• Sufentanyl – 2.5 – 5 mcg
• Diamorphine – 0.3 mg
• Morphine – 0.1 – 0.2 mg

59. Adjuvants used
Epinephrine
• Dose - 0.2 mg
• Decreases blood flow
Clonidine
• Dose – 15 – 45 mcg
• Prolongs duration of sensory analgesia
Neostigmine
• Dose – 5-100 mcg
• Inhibits breakdown of acetylcholine

60. Baricity
Density of a solution in relation to density
of CSF
• Hypobaric solutions : raise against gravity
• Isobaric solutions : tend to remain in the
same sight where they are injected
• Hyperbaric solutions : tend to follow
gravity

61. Factors affecting block height
(postulated)
• Patient characteristics
–Age
–Height
–Weight
–Gender
–Intra abdominal pressure
–Anatomic configuration of spinal column
–Position

62. Factors affecting block height
(postulated)
• Technique of injection
–Site of injection
–Direction of injection
–Direction of the bevel
–Use of barbotage
–Rate of injection

63. Factors affecting block height
(postulated)
• Characteristics of anaesthetic solution
–Density
–Amount
–Concentration
–Temperature
–Volume
–Vasoconstrictors

64. Factors affecting block height
(postulated)
• Characteristics of spinal fluid
–Volume
–Pressure
–Density

65. Factors influencing block height
Controllable factors
• Dose ( volume x concentration)
• Site of injection
• Baricity of local anaesthetic solution
• Posture of patient

66. Factors influencing block height
Factors not controllable
• Volume of CSF
• Density of CSF

67. Levels of block
Sympathetic paralysis
Sensory block
Motor nerve blockade

68. Sequence of nerve modality block
1. Vasomotor block – dilatation of
cutaneous vessels and increased
cutaneous blood flow
2. Block of cold temperature fibres
3. Sensation of warmth felt by the patient
4. Temperature discrimination is lost
5. Los of slow pain
6. Loss of fast pain

69. 7. Tactile sensation is lost
8. Motor paralysis
9. Pressure sense abolished
10. Proprioception and joint sense is lost
Sequence of nerve modality block

70. Testing for levels of block
Sympathetic block
• Skin temperature sensation
• Changes in the skin temperature

71. Testing for levels of block
Sensory level
• Pin prick using sterile needle
• Loss of touch is two dermatomes lower
than pin prick

72. Testing for levels of block
Motor block
• Modified Bromage scale of onset of motor
block

73. Indirect effects of SA drugs
Cardiovascular effects
Due to sympathetic blockade there is
vasodilatation of both resistance and
capacitance vessels
Fall in peripheral vascular resistance
Posture dependent fall in cardiac output
Fall in BP

74. Indirect effects of SA drugs
Cardiovascular effects
• Marey’s law :baroreceptors in the carotid
sinus and the aortic arch normally respond
to a fall in blood pressure by producing a
compensatory tachycardia

75. Indirect effects of SA drugs
Cardiovascular effects
• Bain bridge reflex predominates during
spinal anaesthesia : venous pooling in the
periphery reduces stimulation of volume
receptors - diminishes the action of
cardiac sympathetic nerves- vagal
preponderance - bradycardia
• Oxygen consumption is reduced due to
hypotension and muscle relaxation

76. Indirect effects of SA drugs
Respiratory effects
• High spinal may cause paralysis of
intercostal nerves
• Bronchodilatation secondary to
hypotension or to reduced pulmonary
blood volume

77. Indirect effects of SA drugs
Gastro-intestinal effects
• Contracted bowel and relaxed sphincters
due to sympathetic blockade
• In the absence of vagal block – increase
in peristalsis and intraluminal pressure
Bladder and urogenital dysfunction

78. Spinal anaesthesia in pregnancy
Decreased dose requirement due to
• Mechanical factor : compression of IVC
causes shunting of blood to the venous
plexus in the vertebral canal- decreased
vertebral canal space and CSF volume
• Hormonal factor – higher progesterone
levels

79. Complications
1. Immediate complications
- Hypotension
- Bradycardia and Cardiac arrest.
- High and Total spinal block leading to
respiratory arrest.
- Urinary retention.
- Epidural hematoma, Bleeding.

80. Complications
2. Late complications
- Post dural puncture headache (PDPH)
- Backache
- Nausea
- Focal neurological deficit
- Bacterial meningitis
- Sixth Cranial nerve palsy
- Urinary retention

81. Treatment of complications
Hypotension is due to vasodilation and a
functional decrease in the effective
circulating volume.
1. Vasoconstrictor drugs
2. All hypotensive patients should be given
OXYGEN by mask until the blood pressure is
restored.
3. Raising their legs thus increasing the return
of venous blood to the heart.

82. Treatment of complications
4. Increase the speed of the intravenous
infusion to maximum until the blood pressure is
restored to acceptable levels.
5. Treatment of bradycardia- give atropine
intravenously.

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

84. How to prevent Delayed
Complication
• Use Thin Spinal needles
• Sterile Precaution

85. It is widely considered that pencil-point needles
(Whiteacre or Sprotte) make a smaller hole in the
dura and are associated with a lower incidence of
headache (1%) than conventional cutting-edged n
eedles (Quincke)

87. Treatment of spinal headache
Remain lying flat in bed as this relieves the pain.
They should be encouraged to drink freely or, if
necessary, be given intravenous fluids to mainta
in adequate hydration.

88. Treatment of spinal headache
Simple analgesics such as paracetamol,
aspirin or codeine may be helpful,
Caffeine containing drinks such as tea,
coffee or Coca-Cola are often helpful.

89. Treatment of spinal headache
Prolonged or severe headaches may be
treated with
• epidural blood patch performed by aseptically
injecting 15-20ml of the patient's own blood int
o the epidural space.
• This then clots and seals the hole and
prevents further leakage of CSF.