Regional Anesthesia.final

8/3/2019 Regional Anesthesia.final

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REGIONAL ANESTHESIA

Regional Anesthesia

1. Spinal2. Epidural

3. Peripheral Nerve Block


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BASIC ANATOMY

1. Spinal Canal - from

the foramen magnum to

the sacral hiatus

2. Vertebral Column 33vertebrae

7 cervical

12 thoracic 5 lumbar

5 sacral

4 coccygeal fused


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REGIONAL ANESTHESIA

Contents of Spinal Column

1. Spinal cord

2. Subarachnoid space

3. Epidural space

3 Membranes of SC

1. Pia mater

2. Arachnoid mater

3. Dura mater


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LIGAMENTS

1. Anterior and Posteriorligaments

- between the anteriorand posterior aspectsof vertebral bodies

2. Supraspinatous ligament

- from the 7th cervical

vertebrae to sacrum- maximum thickness atlumbar area


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3. Interspinous ligament

- extends between the spinous process

4. Ligamentum Flavum- yellow elastic fiber, runs from anterior and

inferior aspects of each vertebral lamina below

- most dense at lumbar area


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SPINAL NERVES

1. Somatic Spinal Nerves - dermatome

2. Dorsal and Ventral Spinal Nerves Roots3. Preganglonic Sympathetic Nerve Fibers

4. Cervical Nerves

BLOOD SUPPLY

1. Anterior artery

2. 2 Posterior arteries supply the dorsal portion of thespinal cord

3. Artery of Adamkiewics

- highly variable

- most common on the left and enters the vertebral canalthrough the L1 intervertebral formen.

- supply the lower 2/3 of SC

- damage will produce bilateral lower extremity motor loss


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PREOPERATIVE EVALUATION

1. Surgical Considerations

Sugested Minimum Dermatome Levels for Spinal or Epidural

Anesthetics

Site of Operation Levels Required

Lower Extremity T12

Hip T10

Prostate or Bladder T10

Testes T6Herniorrhaphy T4

Intraabdominal T4


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PREOPERATIVE EVALUATION

3. Contraindication

Absolute: 1. Patient Refusal

2. Infection at site3. Increased ICP

4. bleeding diathesis


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Relative Contraindication:

1. Sepsis

2. Preexisting Neurologic deficits3. Cardiac Disease

- mitral stenosis, idiopathic hypertropic

subaortic stenosis, and aortic stenosis

4. Abnormal Coagulation


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SPINAL ANESTHESIA

- Accomplished by injecting local anesthetic solution

into the CSF contained within subarachnoid space.

Indications: Abdominal Surgery

- General surgery

- Obstetric and Gynecologic

Urologic and Rectal Surgery

Lower extremities


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SPINAL ANESTHESIA

Patient Position

1. Lateral

- lateral decubitus position1. Sitting

2. Prone


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Layers traversed by theSpinal needle:

1. Skin

2. Subcutaneous Ligament3. Supraspinous Ligament

4. Infraspinous Ligament

5. Ligamentum flavum

6. Epidural Space7. Dura

8. Subarachnoid Space


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SPINAL ANESTHESIA

Spinal Needles

1. open-ended (beveled or cutting)

2.

Closed tapered-tip pencil-point needle with sideport (guage 24- or 25-)


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SPINAL ANESTHESIA

Approach

1. Midline

2. Paramedian elderly with calcified ligaments or patient

point of cutaneous needle insertion is typically 1 cm lateral to

the midline-skin

- quadratus lumborum muscle

- Ligamentum flavum

- Epidura

- Dura- subarachnoid space

- does not traverse the supra and infraspinous ligament


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SPINAL ANESTHESIA

3. Taylor Approach

- paramedian technique to access L5-S1

- spine needle is passed from a point 1cm caudadand 1 cm medial to the posterior superior iliac spine

and advanced cephalad at a 55-degree angle

with medial orientation based on the width of the

sacrum.


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SPINAL ANESTHESIA

Anesthetic Injection Checklist:

1. Position

2.

SAAS3. Skin Infiltation

4. Free flow of CSF

5. Paresthesia(-)


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SPINAL ANESTHESIA

LEVEL AND DURATION

Factors affecting the spread of local anesthetic:

1.

Baricity2. Contour of the spinal Cord

3. Position of the patient

4. Drug Dosage

5. Site of Injection


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SPINAL ANESTHESIA

Baricity

1. Hypobaric < 0.997 @ 37C

- procedures on the rectum, perineum and anus or in the lateral decubitusposition

- reduce venous pooling in the legs- limits the cephalad spread of the local anesthetics

2. Isobaric 0.998 1.007 @ 37C

- produce more localized blocks extending only to the thoracicdermatomes

- appropriate for lower extremity and urologic procedures

3. Hyperbaric >1.008 @ 37C

- most commonly selected

-ability to achieve greater cephalad spread of anesthesia

-


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SPINAL ANESTHESIA

Adjuvants1. Vasoconstrictors

- added to increase the duration of spinal anesthesia

- epinephrine

- phenylephrine

1. Opioids and other Analgesics Agent

- Improves sensorimotor blockade

- Provides postoperative anesthesia

- Fentanyl short surgical procedures

- Morphine provide effective control of postoperativepain for roughly 24 hours


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SPINAL ANESTHESIA

CHOICE OF LOCAL ANESTHETIC

Duration of Action

Potential Adverse Side Effects

SHORT-DURATION

1. Lidocaine

2. Cnloroprocaine

LONG-DURATION1. Bupivacaine

2. Tetracaine


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SPINAL ANESTHESIA

Documentation of Anesthesia

SENSORY LEVEL NECESSARY FOR SURGICAL PROCEDURES

Sensory Level Type of Surgery

S2-S5 Hemorrhoidectomy

L2-L3(knee) Foot Surgery

L1-L3 (Inguinal Ligament) Lower Extremity

T10 (umbilicus) Hip Surgery

Transurethral resection of the

prostateVaginal Delivery

T6-T7 (xiphoid process) Lower Abdominal Surgery

Appendectomy

T4 (nipple) Upper Abdominal Surgery

Cesarian Section


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CONTINUOUS SPINAL ANESTHESIA

Levels and significant of Sensory Block

Cutaneous Level Segment

Level

Significance

Fifth Digit C8 All cardioaccelrator fibers block

Inner Aspect of the arm

and forearm

T1-2 Some degree of cardioaccelerator

block

Apex of axilla T3 Easily determined landmark

Nipple T4-5 Possibility of cardioaccelarator

block

Tip of the Xiphoid T7 Splanchnics(t5-L1) may be blocked

Umbilicus T10 Sympathetic NS block limited to thelegs

Inguinal Ligament T12 No sympatheti nervous system block

Outer Side of the foot S1 Confirms block of the most difficultroot to anesthesize


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SPINAL ANESTHESIA

SEQUENCE OF NEURAL BLOCKADE

1. Sympathetic block or Autonomic block

2. Loss of pain and temperature sensation

3. Loss of propioception

4. Loss of touch and pressure sensation

5. Motor paralysis


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SPINAL ANESTHESIA

SYMPATHETIC BLOCKADE

Preganglionic Sympathetic blockade

Arteriolar and Venous Dilatation

Increased Vascular Capacitance

Pooling of Blood

Decreased Venous Return

Decreased Cardiac Output


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SPINAL ANESTHESIA

COMPLICATIONS

Hypotension (


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SPINAL ANESTHESIA

HYPOTENSION MANAGEMENT

1. Modest head down position (5 to 10 degrees)

2. Adequate Hydration

3. Sympathomimetics: Ephedrine (5-10mg IV)

HIGH SPINAL TREATMENT

1. Maintenance of airway and ventilation

2. Circulatory support ( sympathomimetics andintravenous fluid administration)

3. Head Down Position


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EPIDURAL ANESTHESIA

EPIDURAL ANESTHESIA

- injection of local anesthetic into the epidural space

- neural blockade: spinal nerve roots

- anesthesia occurs more slowly and develops in

segmental manner


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EPIDURAL ANESTHESIA

Indications:

- All indications for spinal anesthesia

- Prolong post-op pain relief

Epiduara Needles:

1. Tuohy needle

2. Weiss needle

3. Crawford needle


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EPIDURAL ANESTHESIA

Epidural Catheters:

1. Bullet tipped

2. Multiorifice

Epidural Kit:

1. 17- to 18- gauge needle

2. 19- to 20- gauge catheter

3. Finder needle 3.8 cm


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EPIDURAL ANESTHESIA

TECHNIQUE

1. Thoracic Epidural

- paramedian approach

2. Lumbar and low thoracic epidural

- midline and paramedian approach


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EPIDURAL ANESTHESIA

Identification of Epidural Space

1. Engagement of the needle tip in ligamentum

flavum

2. Loss-of-Resistance technique

3. Hanging Drop technique


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EPIDURAL ANESTHESIA

LAYERS TRAVERSED BY

EPIDURAL NEEDLE:

1. Skin

2. Subcutaneous Tissue

3. Supraspinous

ligament

4. Interspinous ligament5. Ligamentum flavum


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EPIDURAL ANESTHESIA

Administration of Local Anesthetic:

1. Single-Shot epidural Anesthesia

2. Continuous Epidural Anesthesia

3. Caudal Anesthesia

Factors affecting the spread of anesthesia

1. Dose

2. Site of injection


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EPIDURAL ANESTHESIA

Factors affecting the duration of anesthesia:

1. Choice of local aneshetic

a. Chloroprocaine (rapid onset and short duration)

b. Lidocaine (intermediate onset and duration)

c. Bupivacaine, Levobupicaine, Ropivacaine (slow

onset and prolonged duration)


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EPIDURAL ANESTHESIA

Factors affecting hthe duration of anesthesia:

2. Adjuvants

a. Epinephrine

b. Opioids

c. Sodium BicarbonateFailed Epidural Anesthesia

- Local anesthetics solution is not delivered into the epidural space

- Spread of local anesthetics is inadequate to cover the relevantdermatomes

- False loss of resistance- Advancement of the catheter through intervertebral foramen


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EPIDURAL ANESTHESIA

Sequence of Neural Blockade

1. Sympathetic Nervous System Blockade

2. Motor Block

3. Catabolism


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EPIDURAL ANESTHESIA

COMPLICATIONS

Hypotension (


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COMBINED SPINAL-EPIDURAL

ANESTHESIA

- combines the rapid onset and intense sensory

anesthesia of the spinal anesthetic with the ability to

supplement and extend the duration of the block

afforded by an epidural catheter.


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CAUDAL ANESTHESIA

- Special form of epidural anesthesia, with access

through sacral hiatus

- Sacral hiatus is located 5cm from the tip of coccyx

- Failure rate of 10 to 15%

- More useful in pediatric patients


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PERIPHERAL NERVE BLOCK

- Used for anesthesia, post operative analgesia, and

diagnosis and treatment of chronic pain syndrome

PREPARATION FOR NERVE BLOCKS

- Same as general anesthesia or neuroaxial

anesthesia

- Preoperative medication

- Appropriate monitors, equipment and drugsavailable for adverse reaction


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FACTORS IN CHOICING LOCAL ANESTHETICS

1. Desired Onset

2. Duration

3. Degree of Conduction Block


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Local Anesthetic Agent and

Local

Anaesthetics

Duration

Lidocaine

Mepivacaine

1%-5% 10-20 minutes

to 2-3 hours

Surgical

anesthesia

Ropivacaine

Bupivacaine

0.5%

0.375%-0.5%

6-8 hours


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Specific Block Techniques

1. Paresthesias

- radiating electric shock-like sensations that can occurduring regional anesthetic procedures.

2. Nerve Stimulation- common way of identifying peripheral nervesthat carrymixed populationof sensory and motor fibers.

CATHODAL STIMULATION

- block needle - cathode-another lead on the body anode

- 0.5mA indicates sufficient proximity of the block needleto the nerve .


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TYPE OF PERIPHERAL NERVE BLOCK

A. Brachial Plexus Block

1. Interscalene Block

2. Supraclavicular Block

3. Musculocutaneous Nerve Block

4. Intercostobrachial Nerve Bolock

5. Distal Nerve Block of the Arm

6. Ulnar Nerve Block

7. Radial Nerve Block


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B. Blocks of the Thoracic and Abdominal Walls

1. Intercostal Nerve Block

2. Block of the Inguinal Region

C. Block of the Inguinal Region

D. Nerves Block to the Lower Extremity

1. Lumbar Plexus Block

2. Femoral Nerve Block

3. Lateral Femoral Cutaneous Nerve Block

4. Sciatic Nerve Block

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