SPINAL ANAESTHESIA Anaesthesiology .pptx

SPINAL ANAESTHESIA
spinal anesthesia/anesthesiology/184-244 1

Objectives
• At the end of this lecture, the students should be able
to
- know the history of spinal anaesthesia
- define spinal anaesthesia
- know the anatomy related to spinal anaesthesia
- know the indications and contraindications of SAB
- perform the technique of SAB
- identify the complications
- solve the complications
- know the factors affecting to the spread of spinal
anaesthesia
- differentiate between spinal and epidural anaesthesia

Advantages of spinal anesthesia
1. Cost. The costs associated with SPA are
minimal.
2. Patient satisfaction. the majority of patients are
very happy with this technique.
3. Respiratory disease. SPA produces few
adverse effects on the respiratory system as
long as unduly high blocks are avoided.
4. Patent airway. As control of the airway is not
compromised, there is a reduced risk of airway
obstruction or the aspiration of gastric
contents.
3
spinal anesthesia/anesthesiology/184-244

5. Diabetic patients. There is little risk of unrecognised
hypoglycaemia in an awake patient.
6. Muscle relaxation. SPA provides excellent muscle relaxation
for lower abdominal and lower limb surgery.
7. Bleeding. Blood loss during operation is less than when the
same operation is done under general anaesthesia.
4

5
8. Splanchnic blood flow. Because of its effect on increasing
blood flow to the gut, spinal anaesthesia reduces the
incidence of anastomotic dehiscence.
9. Visceral tone. The bowel is contracted by SPA and
sphincters relaxed although peristalsis continues. Normal
gut function rapidly returns following surgery.
10. Coagulation. Post-operative deep vein thromboses and
pulmonary emboli are less common following spinal
anaesthesia.

Spinal Anaesthesia
• Spinal, or sub-arachnoid block is a form of regional anaesthesia
involving the injection of local anaesthetic into the sub-
arachnoid using a fine needle. This produces surgical
anaesthesia to a part of the body.

SPINAL ANAESTHESIA
• Subarachnoid block
• Intrathecal block
• Central neural block
• Definition
Injection of local anesthetic agents into the subarachnoid
space to produce transient motor, sensory & autonomic block.

History
• 1885- Corning USA (dog)
• 1898- August Bier
• 6 patients for lower extremity surgery
• Nausea, vomiting & headache!!
• Received spinal from colleague, Dr Hildebrandt
• Headache!!!

Anatomy 1
• 33 vertebrae; 7
cervical, 12
thoracic, 5 lumbar,
5 sacral (4
coccygeal
remnants).
• 3 curves

Anatomy 2
• 5 ligaments hold the
spinal column
together;
supraspinous,
interspinous,
ligamentum flavum.
Anterior & posterior
ligaments

Anatomy 3
• 3 membranes; pia, arachnoid & dura
• Dura outermost layer, to S2,
• Arachnoid also to S2 is middle. Subdural between.
• Sub arachnoid space contains spinal nerves and CSF
• Pia clings to surface of cord

Anatomy 4 – Anatomical layers
• Skin
• Subcutaneous fat
• Supraspinatus
• Interspinatus
• Ligamentum flavum
• Epidural space
• Dura
• Subdural space
• Arachnoid
• Sub-arachnoid space

Layers passing through the spinal needle during
spinal anesthesia

Anatomy 5
• Length of spinal cord varies with
age
• Adults;
• Majority @ L1
• 10% L3
• 13% T12

Paravertebral Block
• Injects local anaesthetic adjacent to thoracic vertebra where
spinal nerves emerge.
• Unilateral block, useful for hernia, mastectomy etc.
• Ultrasound

Local Anaesthetics
• Block Na Channels in nerve membrane, thus preventing
progression of Action Potential
• Site of Action – nerve roots and spinal cord
• 4 factors in uptake of local anaesthetic
• Concentration of LA in CSF
• Surface area of nerve tissue exposed to CSF
• Lipid content of nerve tissue
• Blood flow

Local Anaesthetics
• Spinal cord and nerves are mixed nerves
• LA blocks smaller, unmyelinated first , larger myelinated last
• May see variable clinical picture

Nerve sizes
• Aα Motor neurone
• Aδ Sensory, touch & pressure
• C Nocioceptors, temperature
• B preganglionic autononic
• C postganglionic autonomic

Local Anaesthetics
• Cocaine
• Lignocaine (lidocaine) (5% heavy lignocaine )
• Bupivacaine ( 0.5 % heavy bupivacaine )
• Prilocaine
• Tetracaine

Adjuncts
• Adrenaline
• Opiods
• Morphine, fentanyl, diamorphine

Physiological changes in spinal anaesthesia
• CNS
Order of blocking nerve fibres
(1) Autonomic preganglionic B fibre
(2) Temperature fibre (cold before warm)
(3) Pinprink fibre
(4) Fibre conveying pain greater than
pinprick
(5) Touch fibre
(6) Deep pressure fibre
(7) Somatic motor fibre
(8) Fibre conveying vibratory sense and
priopioceptive impulses

• CVS
- Vasodilatation of resistance & capacitance vessels
- Hypotension
- Bradycardia if block above T4
• Respiratory System
- Diaphragm remain uneffected
- Ascending block of intercostals muscle causes difficulty in
breathing

• Viscera
- Gut- small contracted gut with active peristalsis
- Bladder- atonic bladder
• Renal
- RBF& GFR remain uneffected except extreme
hypotension
• Neuroendocrine
- Block the complex neural & hormonal stress
response to surgery

Indications
• Lower limb surgery e.g. ORIF , amputation
• Lower abdominal surgery e.g. appendiectomy ,
hydrocele ,hernia
• Perianal region surgery e.g. pile, fistula , fissure
• Obstetric e.g. LSCS
• Gynecological surgery e.g: TAH ,VH , sterilization
• Urological surgery e.g. TURP ,TVP

Contraindications
• (A) Absolute contraindications
1.Patient refusal
2.Localized infection at the site of injection
3.Generalized infection or septicemia
4.Coagulopathy
5.Increased ICP
6.Severe hypovolemia or shock
7.Fixed cardiac output condition eg: severe
AS
8. Allergic to local anaesthetics

Contraindications
(B) Relative contraindications
1. Localized infection peripheral to the site of
injection
2. Backache
3. Patient taking platelet inhibitory drugs e.g.
aspirin

How to perform the spinal injection?
• Clean the patient’s back with antiseptic.
• Locate a suitable interspinous space.
• Raise an intradermal wheal of LA agent at
proposed puncture site.
31

How to perform the spinal injection? continue
32
 Insert the needle: the structures that will be passed skin ,
subcutaneous tissue, supraspinous ligament , interaspinous
ligament , lagementum flavum , epidural space, dura mater,
subdural space, arachnoid matter, and then subarachnoid
space.
 When CSF appears then slowly inject the local anesthetic.

Complications
• Hypotension & bradycardia
- Hypotension - SBP < 90 mmHg or
reduction of BP > 20 % of preoperative
value
- Bradycardia - HR < 60 beats per minute
- Treatment - maintain intravascular volume with NS or RL
- HR < 60 BPM – iv atropine
- HR > 60 BPM – iv ephedrine
- 5 degree head down tilt.

Complications
Dyspnea - reassurance of the patient
- adequate ventilation must be ensured
 Apnea - Immediate ventilatory support is
required
 Paresthesias - Direct trauma to the spinal
nerve or intraneural injection

Complications
Blood tap - d/t puncture of epidural veins
Tx - needle s/b withdrawn & reinserted
 Nausea & vomiting - d/t hypotension or
unopposed vagal
stimulation
Tx - restoration of BP
- administration of oxygen
- iv atropine
- antiemetic - care s/b taken
because it may cause hypotension

Complications
-Post dual puncture headache (PDPH)
- occipital headache
- worsened by patient sitting upright
- improved by lying down
- accompanied by tinitus, blurred vision,
diplopia
- onset is usually 24-48 hours postop
- d/t continuous leak of CSF through the
dura hole which reduce CSF pressure & produce
traction of meningeal vessel & nerve

Treatment of PDPH
- initial conservative treatment include bed rest
and iv fluids & analgesic
- caffeine (300 mg orally ) or caffeine benzoate
(500 mg in 500 ml of NS iv over 2 hours )
- epidural blood patch - placement of 10- 15 ml of
autologus blood into the epidural space if
headache is severe or persist > 24 hrs
- success rate 65%-- 95%

Complications
 Backache
- d/t flattening of the normal lumber lordosis
during muscle relaxation with resultant
stretching of joint capsule ligament &
muscle.
- treatment with analgesic & reassurance
 Infection - chemical and viral or bacterial
infection

Complications
• Neurological impairment
- m/b direct (e.g. needle trauma)
- toxic ( introduction of chemicals ,virus or bacteria)
- ischemic ( e.g. vascular compromise from compression
by an extra dual hematoma)
- transient radicular irritation (last 2-7 days)

Factors Affecting Spread of spinal anaesthesia

Factors affecting spread of spinal Block
 Local Anaesthetic
 Baricity
 Dose
 Volume
 Specific Gravity
 Patient
 Position
 Height
 Spinal column anatomy
 Decreased CSF volume (pregnancy)

Factors affecting spread of spinal Block 2
• Technique
• Site of injection
• Speed
• Bevel direction
• Variability in CSF volume makes accurate prediction of the
level of spinal blockade difficult, even if BMI considered.

Surface Anatomy
• T4 – Nipple level
• T6 – Xiphisternum
• T10 – Umbilicus
• L4-5 _ Illiac Crest (Tuffier’s Line)

Surface Anatomy
• Upper Abdominal T4 2.5-3mls
• Gynae/ Urology T6-10 2-2.5mls
• Vaginal delivery T10 1.5-2mls
• Hip, Knee Rep. T12-L1 1.5-2mls
• Foot/Ankle L2 1.5mls
• Perineal S2-5 1ml

Needle design
• Size and shape of needle determine size of hole and risk of
PDPH

Differences between Spinal and Epidural
Anesthesia
47
Spinal anaesthesia Extradural Anaesthesia
Level: below L1/L2, where the spinal cord
ends
Level: at any level of the vertebral column.
Injection: subarachnoid space i.e punture
of the dura mater
Injection: epidural space (between
Ligamentum flavum and dura mater) i.e
without punture of the dura mater
Identification of the subarachnoid space:
When CSF appears
Identification of the Peridural space:
Using the Loss of Resistance technique.
Doses: 2.5- 3.5 ml bupivacaine 0.5%
heavy
Doses: 15- 20 ml bupivacaine 0.5%
Onset of action: rapid (2-5 min) Onset of action: slow (15-20 min)
Density of block: more dense Density of block: less dense
Hypotension: rapid Hypotension: slow

SPINAL ANAESTHESIA Anaesthesiology .pptx

Recommended

Recommended

More Related Content

Similar to SPINAL ANAESTHESIA Anaesthesiology .pptx

Similar to SPINAL ANAESTHESIA Anaesthesiology .pptx (20)

Recently uploaded

Recently uploaded (20)

SPINAL ANAESTHESIA Anaesthesiology .pptx