Transcript 1433 REGIONAL ANEASTHESIA 0442012-05

REGIONAL ANALGESIA AND
ANAESTHESIA
DEPT OF ANAESTHESIA AND ICU
COLLEGE OF MEDICINE
KING SAUD UNIVERSITY
HISTORY
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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
Cousins & Bridenbaugh, 3rd
Edition
Regional/Neuraxial Anaesthesia
A reversible loss of sensation in a specific
area of the body.
Bier block
Axillary, Interscalene
Spinal, Epidural
Caudal
Ankle block, metatarsal block
Paracervical
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
• Spinal
lower extremities, lower abdomen, pelvis
• Epidural
cervical
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
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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
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 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 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 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 effectivepatient 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
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BUPIVACAINE
LIDOCAINE
ROPIVACAINE
MEPIVACAINE
PRILOCAINE
MAX / DOSE
2 MG/KG
7 MG/KG
4 MG/KG
7 MG/KG
6MG/KG
LOCAL ANAESTHETICS
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 (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)
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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
(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 lowerextremity 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
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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