Transcript LECTURE 5-Regional Anaesthesia Techniques DR FATMA

Lecture Title : Regional Anaesthesia
Techniques
Lecturer name: DR. FATMA AL-DAMMAS
ASSISTANT PROFESSOR
DEPT OF ANAESTHESIA AND ICU
COLLEGE OF MEDICINE
KING SAUD UNIVERSITY
Lecture Date:
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 Anaesthesia
1. 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 Anaesthesia
Discuss 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
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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 block
Axillary, Interscalene
Spinal, Epidural
Caudal
Foot block, metatarsal block
Paracervical
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
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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
• Spinal
lower extremities, lower abdomen, pelvis
• Epidural
cervical
thoracic
lumber
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
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 block
Lumbar-T4
Thoracic-T2
INSERTION OF EPIDURAL CATHETER
• Positioning of patient
• The site is dependent upon the area of pain
• Fixing the catheter
Incision
Level
Thoracic
Upper abdo
Lower abdo
Pelvic
Lower extremity
T4-T6
T6-T8
T8-T10
T8-T10
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
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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
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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
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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 effectivepatient 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
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AMIDES
MAX / DOSE
BUPIVACAINE
LIDOCAINE
ROPIVACAINE
MEPIVACAINE
PRILOCAINE
2 MG/KG
7 MG/KG
4 MG/KG
7 MG/KG
6MG/KG
LOCAL ANESTHETICS
ESTERS
CHLOROPROCAINE
COCAINE
NOVOCAINE
TETRACAINE
MAX /DOSE
20 MG/KG
3 MG/KG
12 MG/KG
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. Pain
2. Cold
3. Warmth
4. Touch
5. Deep pressure
6. Motor function
EPIDURAL LOCAL ANESTHETIC(MARCAINE)
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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)
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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)
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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 lowerextremity 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
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Unconsciousness
Generalized convulsions
Coma
Apnea
Numbness of the mouth and tongue, metal
taste in the mouth
S/S CNS Toxicity
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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
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Thiopental 100 mg to 150 mg IV
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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
Reference book and the
relevant page numbers..
Thank You 
Dr.
Date: