Lecture Title : Regional Anaesthesia Techniques

Lecture Title Lecture Title : Regional Anaesthesia Techniques

Lecturer name: Lecturer name: DR. FATMA AL-DAMMAS

ASSISTANT PROFESSOR DEPT OF ANAESTHESIA AND ICU

COLLEGE OF MEDICINEKING SAUD UNIVERSITY

Lecture Date:Lecture Date:

Lecture Objectives..Lecture Objectives..

Students at the end of the lecture will be able to: understand

1.What are the risks and benefits of regional (epidural/spinal) anesthesia/analgesia?

2.What are the contraindications to regional anesthesia?

3.How do you prevent hypotension following epidural/spinal anesthesia?

Spinal Anaesthesia1. Describe the technique of spinal anesthesia.2. At what level does the adult spinal cord end?3. Name some of the surgical procedures that can be done with a spinal

anesthetic.4. What are the contraindications to spinal anesthesia?5. What are the complications?6. Describe the patient's perception as spinal anesthetic takes effect.7. What are the expected cardiovascular changes associated with sensory

level at T10? T1?8. What are the characteristics of post-lumbar puncture headache?9. How do the size and tip design of a spinal needle influence the incidence

of post-puncture headache?10. How do you treat post-lumbar puncture headache?

Epidural AnaesthesiaDiscuss the differences between spinal and epidural anesthesia.1. What are the advantages and disadvantages of epidural

compared to spinal anesthesia?2. Study the size and tip of the epidural needle.3. Name some of the surgical procedures that can be done with

an epidural anesthetic.4. Compare and contrast lumbar and thoracic epidural

anesthesia.5. What role does epidural has for post-operative pain control?6. Local Anesthetics Pharmacology and toxicity (Lidocaine,

Bupivacaine)

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

needle• 1963 Bupivicaine commercially available • 1979 Cousins - Epidural opioids provide analgesia• 1983 Yaksh - Different spinal receptor systems mediating pain • 1985 University of Kiel, Germany, Anesthesiology managed

acute post-operative pain service

Cousins & Bridenbaugh, 3rd Edition

Regional/Neuraxial Anesthesia

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

Bier blockAxillary, InterscaleneSpinal, EpiduralCaudalFoot block, metatarsal blockParacervical

Regional anesthetic techniques categorized as follows

• Epidural and spinal anesthesia• Peripheral nerve blockades• IV regional anesthesia

DEFINITIONS

• SPINAL ANESTHESIA

• INTRATHECAL=administration of medication into subarachnoid space

DEFINITIONS

• EPIDURAL ANESTHESIA

• 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, lumber5, sacral 5, coccygeal3.

anatomy

EPIDURAL SPACE

• Potential space• Between the dura mater,luigamentum flavum • Made up of vasculature, nerves, fat and lymphatic• Extends from foramen magnum to the

sacrococcygeal ligament

Regional anesthesia

• Spinallower extremities, lower abdomen, pelvis

• Epiduralcervicalthoraciclumbercaudal

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

ABSOULET CONTRAINDICATION • Patient refusal • Known allergy to opioid or local anesthetic • Infection/abscess near the proposed injection site• Hematological disorder• Increase ICP

CONTRAINDICATIONS

RELATIVE CONTRAINDICATION • Sepsis• AntiCoagulant drugs• 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 catheterIncision LevelThoracic T4-T6Upper abdo T6-T8Lower abdo T8-T10Pelvic T8-T10Lower 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 up the catheter is 5cm = double mark up the catheter is 10 cm = triple mark on the catheter is 15 cm = four mark together indicate 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 LOC Decrease loss of sensory or motor loss (marcain) Toxicity Profound hypotension

CATHETER MIGRATION

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

Advantages/Disadvantages of Regional and Local Anesthesia.

advantages

• patient remains conscious• maintain his own airway• aspiration of gastric contents unlikely• smooth recovery requiring less skilled nursing

care as compared to general anesthesia

advantages

• postoperative analgesia• reduction in surgical stress• earlier discharge for outpatients• less expense

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 anesthetic

Disadvantages:

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

• some operations are unsuitable for local anesthetics, 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 ANESTHETICS

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

LOCAL ANESTHETICS

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 (subanesthetic 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 anesthesia

• Loss of:1. Pain2. Cold3. Warmth4. Touch5. Deep pressure6. Motor function

EPIDURAL LOCAL ANESTHETIC(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 N/V-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 anesthetic 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 Anesthesia Toxicity

• CNS• CV

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 Anesthesia 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

LidocaineBupivacaineLevobupivacaineRopivacaineMepivacaineEtidocainePrilocaine

– Esters

Procaine

Chloroprocaine

Tetracaine

Benzocaine

Cocaine

Reference book and the Reference book and the relevant page numbers..relevant page numbers..

DrDr..

Date: Date:

TThank You hank You