REGIONAL ANALGESIA AND ANAESTHESIA

DEPT OF ANAESTHESIA AND ICUCOLLEGE OF MEDICINEKING SAUD UNIVERSITY

Cousins & Bridenbaugh, 3rd Edition

HISTORY

• 1885 Corning - First attempt with epidural cocaine• 1891 Quincke - Describes the lumbar puncture technique• 1921 Pagis - First lumbar anaesthesia for surgery• 1947 Lidocaine commercially available• 1949 Curbelo - First continuous lumbar analgesia with

Touhy needle• 1963 Bupivacaine commercially available • 1979 Cousins - Epidural opioids provide analgesia• 1983 Yaksh - Different spinal receptor systems mediating

pain • 1985 University of Keil, Germany, Anaesthesiology

managed acute post-operative pain service

Regional/Neuraxial Anaesthesia

A reversible loss of sensation in a specific area of the body.

Bier blockAxillary, InterscaleneSpinal, EpiduralCaudalAnkle block, metatarsal blockParacervical

Regional anaesthetic techniques categorized as follows

• Epidural and spinal anaesthesia

• Peripheral nerve blockades

• IV regional anaesthesia

• SPINAL ANAESTHESIA

• INTRATHECAL=administration of medication into subarachnoid space

• EPIDURAL ANAESTHESIA

• EPIDURAL=administration of medication into epidural space

OVERVIEW

OF THE

SPINAL ANATOMY

SPINAL CORD

• Located and protected within vertebral column• Extends from the foramen magnum to lower border

1st L1 (adult) S2 (kids)• SC taper to a fibrous band - conus medullaris• Nerve root continue beyond the conus- cauda

equina• Surrounded by the meninges (dura ,arachnoid & pia

mater.)

anatomy

• The vertebrae are 33 number, divided by structural into five region: cervical 7, thoracic 12, lumbar 5, sacral 5, coccygeal 3.

anatomy

EPIDURAL SPACE

• Potential space• Between the dura mater,ligamentum flavum • Made up of vasculature, nerves, fat and

lymphatics.• Extends from foramen magnum to the

sacrococcygeal ligament

Regional anaesthesia

• Spinallower extremities, lower abdomen, pelvis

• Epiduralcervical

thoracic

lumbar

caudal

INDICATIONS

The objective of epidural analgesia is to relieve pain.

Major surgery

Trauma (# ribs)

Palliative care (intractable pain)

Labour and Delivery

abd surgery

Pelvic surgery

lower lime surgery

CONTRAINDICATIONS

ABSOLUTE CONTRAINDICATIONS • Patient refusal • Known allergy to opioid or local anaesthetic • Infection/abscess near the proposed injection site• Hematological disorder• Increase ICP

CONTRAINDICATIONS

RELATIVE CONTRAINDICATIONS • Sepsis• Patient on anticoagulant• Hypotension• Hypovolemia• Spinal deformity• Neurological disorder.

Patient assume a sitting or side-lying position with the back arched toward the physician.Help to spread the vertebrae apart

Height of sensory blockLumbar-T4Thoracic-T2

INSERTION OF EPIDURAL CATHETER

• Positioning of patient• The site is dependent upon the area of pain• Fixing the catheter

Incision LevelThoracic T4-T6

Upper abdo T6-T8

Lower abdo T8-T10

Pelvic T8-T10

Lower extremity L1-L4

EPIDURAL CATHETERS• Ideal Placement (adult) 10-12 cm at the

skin• Epidural catheters have markings that

indicate their length. = there is a mark at the tip of the catheter = the 1st single mark at the catheter is 5cm = double mark at the catheter is 10 cm = triple mark at the catheter is 15 cm = four mark indicates 20cm

A change in depth of the catheter indicates migration either into or out of the epidural space.

CATHETER MIGRATION

Catheter migration into a blood vessel in the epidural space or subarachnoid space

Rapid onset LOCDecrease loss of sensory or motor loss

(marcain)ToxicityProfound hypotension

CATHETER MIGRATION

Out of the epidural space• ineffective analgesia• no analgesia• drugs deposited into soft tissue.

Advantages/Disadvantages of Regional and Local Anaesthesia.

advantages

• patient remains conscious

• maintain his own airway

• aspiration of gastric contents are unlikely

• smooth recovery requiring less skilled nursing care as compared to general anaesthesia

advantages

• postoperative analgesia

• reduction in surgical stress

• earlier discharge for outpatients

• less expensive

Disadvantages:

• patient may prefer to be asleep• practice and skill is required for the best

results.• some blocks require up to 30 minutes or more

to be fully effective• analgesia may not always be totally effective-

patient may require additional analgesics, IV sedation, or a light general anaesthetic

Disadvantages:

• toxicity may occur if the local anaesthetic is given intravenously or if an overdose is injected

• some operations are unsuitable for local anaesthetics, e.g., thoracotomies

DRUGS

• One of the most important factors influencing drug absorption and bioavailability is the drug SOLUBILITY

• The more lipid soluble rapid onset & shorter duration

MEDICATION COMMONLY USED

• OPIOIDS-Fentanyl +Morphine

(affect the pain transmission at the

opioid receptors)

• L.A.-Bupivacaine(marcaine)

(inhibits the pain impulse

transmission in the nerves with

which it comes in contact)

LOCAL ANAESTHETICS

AMIDES MAX / DOSE

• BUPIVACAINE 2 MG/KG• LIDOCAINE 7 MG/KG • ROPIVACAINE 4 MG/KG• MEPIVACAINE 7 MG/KG• PRILOCAINE 6MG/KG

LOCAL ANAESTHETICS

ESTERS MAX /DOSE

CHLOROPROCAINE 20 MG/KG

COCAINE 3 MG/KG

NOVOCAINE 12 MG/KG

TETRACAINE 3 MG/KG

Metabolism

• Amides– Primarily hepatic– Plasma conc. may

accumulate with repeated doses

– Toxicity is dose related, and may be delayed by minutes or even hours from time of dose.

• Esters– Ester hydrolysis in the

plasma by pseudocholinesterase

– Almost no potential for accumulation

– Toxicity is either from direct IV injection

• tetracaine, cocaine

or persistent effects of exposure

• benzocaine, cocaine

Clinical Pharmacology

Patients with genetically abnormal pseudocholinesterase are at increased risk for toxic side effects, as metabolism is slower.

Clinical Pharmacology

CSF lacks esterase enzymes, so the termination of action of intrathecally injected ester local anesthetics, eg, tetracaine, depends on their absorption into the bloodstream.

METHODS OF ADMINISTRATION

BOLUS (FENTANYL, DURAMORPH)

CONTINUOUS INFUSION(MARCAINE+FENTANYL)

All drugs administered epidural should be preservative free.

All epidural opioids should be diluted with normal saline prior to intermittent bolus administration.

Mechanism of Action

Bupivacaine (marcaine) - local anaesthetic works as an

analgesic (subanaesthetic dose)

- inhibiting impulse transmission in

the nerve fibers

- sensory nerves are blocked first

before the motor fibers

- sensory fibers carrying the pain is

blocked before those carrying heat,

cold, touch and pressure.

Progression of local anaesthesia

• Loss of:1. Pain

2. Cold

3. Warmth

4. Touch

5. Deep pressure

6. Motor function

EPIDURAL LOCAL ANAESTHETIC(MARCAINE)

• Onset 10-15 minutes• Duration- 4 hrs+ after a bolus or after infusion is

stopped• Marcaine(0.0625%-0.125%-0.25%)• Extend of spread influenced by volume and position

of patient

OPIOIDS

Mechanism of action-distribution

Vascular uptake by blood vessels in the epidural

space

Diffusion through dura into CSF to spinal cord to the site of action.

Uptake by the fat in the epidural space.

Morphine (Duramorph/Astramorph)

• Hydrophilic(water soluble)• Slow to diffuse across the dura on to the spinal cord• Can cause late respiratory depression• Monitor respiratory status for 12 hrs after the last

dose of duramorph• Duration 6 hrs+• Broad spread

Fentanyl (preservativefree)

• Lipophilic(fat soluble)• Crossess the dura rapidly• Rapid onset of action(segmental)• Decreased risk of late respiratory depression• Onset 5-20 mins• Duration 2-4hrs• Excellent for breakthrough pain

Adverse Effects -Opioids Sedation and resp.depression- IV narcan

(Naloxone) Nausea / Vomiting- Opioids stimulate the chemoreceptor

trigger zone

primperan Pruritus- diphenhydramine or narcan (low dose) Urinary retention- low dose narcan and /or

catheterization Slowing of GI motility Hypotension

Adverse Effects L.A

• Hypotension- -assess intravascular

volume status

-no trendelenberg positioning

• Teach patient to move slowly from a lying position to sitting to standing position.

Treatment• fluids

Cont.• Temporary lower-

extremity motor or sensory deficits.

Tx: lower the rate or

concentration.

• Urine retention

Tx: catheter

• Local anaesthetic toxicity (neurotoxicity)

Tx: stop infusion.

• Resp. insufficiency

Tx:stop infusion

- ABC(100% o2

call for help)

- Assess spread

and

height of block

- Alt.analgesia

OTHER COMPLICATIONS

• Headache (dural puncture)

Tx: symptomatic treatment Autologous blood patch

• Infection• nausea and vomiting.

• Intravenous placement of catheter

• Subdural placement of catheter

• Haematoma

Signs and Symptoms of Local/Regional Anaesthesia Toxicity

• CNS

• Cardiovascular

S/S CNS Toxicity

• Unconsciousness

• Generalized convulsions

• Coma

• Apnea

• Numbness of the mouth and tongue, metal taste in the mouth

S/S CNS Toxicity

• Light-headedness

• Tinnitus

• Visual disturbance

• Muscle twitching

Cardiovascular toxicity

• slowing of the conduction in the myocardium

• myocardial depression

• peripheral vasodilatation

Prevention and Treatment of Local/Regional Anaesthesia Toxicity

prevention• Always use the recommended dose• Aspirate through the needle or catheter before

injecting the local anesthetic. Intravascular injection can have catastrophic results.

• If a large quantity of a drug is required, use a drug of low toxicity and divide the dose into small increments, increasing the total injection time

• always inject slowly (<10 ml/min) and communicate with the pt

treatment

• All necessary equipment to perform resuscitation, induction, and intubation should be on hand before injection of local/regional anesthetics

• Manage airway and give oxygen• Stop convulsions if they continue for more

than 15 to 20 seconds– Thiopental 100 mg to 150 mg IV

– or Diazepam 5 mg to 20 mg IV

OTHER BLOCKS

Caudal Anaesthesia

Anatomy of Lumbar and Sacral Plexus

Classes: The rule of “i”

• Amides

Lidocaine

Bupivacaine

Levobupivacaine

Ropivacaine

Mepivacaine

Etidocaine

Prilocaine

– Esters

Procaine

Chloroprocaine

Tetracaine

Benzocaine

Cocaine