Transcript Regional Anesthesia Priciples

Regional Anesthesia - Principles
PFN:18DAAL05
Hours: 1.0
Updated: AUG 2012
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Slide 1
Regional Anesthesia - Principles

Agenda
 Review physiology of nerve impulse conduction
 Identify equipment
and preparation to provide
peripheral nerve blocks
 Identify types of local anesthetic agents,
characteristics, and risk factors
 Indentify techniques of risk mitigation in
performance of regional blocks
 Identify nerve stimulation theory
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Slide 2
Regional Anesthesia - Principles

References
 Military Advanced Regional Anesthesia and
Analgesia Ch. 2 – 4, & 25
 Pathophysiology for the Health Professions 4th
Edition Ch. 6 p.126
 Basis Guide to Anesthesia for Developing
Countries, Volume 2, Daniel D. Moos
(International Federation of Nurse
Anesthetists, ifna-int.org)
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Slide 3
Regional Anesthesia - Principles

Conduction of Nerve Impulse
 Depolarization
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Slide 4
Regional Anesthesia - Principles

Conduction of Nerve Impulse
 Repolarization
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Slide 5
Regional Anesthesia - Principles

Conduction of Nerve Impulse
 Blocking Impulse with Locals
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Slide 6
Regional Anesthesia - Principles

The goal in regional anesthesia
 Target nerves proximal to source of pain
• Surround “targeted” nerve with agents thus
preventing depolarization prior to perception by
CNS
• Lowering or eliminating systemic pain medications
• Lowering or eliminating negative CNS side effects of
systemic medications
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Slide 7
Regional Anesthesia - Principles

Methods of targeting proximal nerves
 Paraesthesia “Blind” or “anatomical”
• Less equipment
• More suitable for distal blocks
 Nerve Stimulation *
• Specialized equipment
• Allows very proximal blocks
 Ultrasound guided
• Specialized equipment
• Allows visualization of targeted nerves
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Slide 8
Regional Anesthesia - Principles
Methods of targeting proximal nerves
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Slide 9
Regional Anesthesia - Principles
"This technology can only confirm and
refine correct needle placement for
regional blocks; it should never be
considered a substitute for the
physician's understanding of the
anatomical basis for each block.”
Military Advanced Regional Anesthesia and Analgesia
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Slide 10
Regional Anesthesia - Principles

Regional Block Contraindications
 Adamant refusal by the patient
 Infants, children, or the elderly
 Localized infection at the injection site
 Systemic anticoagulation / coagulopathy
 Obese patients
 Pre-existing neurological disease
 Inadequate communication
capability
 History of traumatic injury at block site
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Slide 11
Regional Anesthesia - Principles

Preparation (Patient consent and
education)
 Avoid using blocked extremity for 24 hours
 Protective reflexes and proprioception
decreased
 Location
• Calm/Quiet location
• Adequate “set up” time

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The most common cause of “failed” regional anesthesia is
impatience
Slide 12
Regional Anesthesia - Principles
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Preparation (Specific Gear)
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Ruler and marking pen
Lidocaine to anesthetize skin
Chlorhexidine gluconate skin cleaner
Local anesthetic for block
Peripheral Nerve Stimulator
Needle
• Stimulating
• Non-stimulating
Sterile gloves
Assistant
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Slide 13
Regional Anesthesia - Principles
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Stimulator and gear
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Slide 14
Regional Anesthesia - Principles
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Patient marking prior to block
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Provides memory cues, acts as a rehearsal, instills
confidence in the patient, focuses your attention
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Slide 15
Regional Anesthesia - Principles

Local Anesthetics Blocking Considerations
 Nerve Composition
• Size
• Myelination
• Stimulation
 Agents
• Potency (lipid solubility)
• Duration
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Slide 16
Regional Anesthesia - Principles

Local Anesthetics Agents
 Lidocaine (30-60
minute duration)
• Short to medium acting, most versatile, considered
too short acting for post operative pain
management
 Mepivacaine (45-90 minute duration)
• Medium acting, less neurotoxic and cardiotoxic
than lidocaine; very attractive agent due to low
toxicity, rapid onset, and a dense block
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Slide 17
Regional Anesthesia - Principles

Local Anesthetics Agents
 Ropivacaine (120-360
minute duration)
• Considered the safest long acting agent, long acting
agent of choice at Walter Reed due to safety profile
and efficacy
 Bupivacaine (120-240
minute duration)
• Considered a long acting agent, longest latency to
onset time frame, low cost, propensity for sensory
versus motor blockade; cardiac toxicity high if
intravascular injection occurs
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Slide 18
Regional Anesthesia - Principles

Preparation (Equipment)
 Basic Gear
• Monitor
• Oxygen
• Suction
• Airway adjunct capability
• Emergency hemodynamic equipment
 Advanced Gear
• ACLS (defibrillation)
• Intralipids
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Slide 19
Regional Anesthesia - Principles

Local Anesthetics(Risk Factors)
 Neurotoxicity
 CNS Toxicity
 Cardiac Toxicity
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Stay out of vessels and keep the dosing in
prescribed ranges
For every clinical situation, the use of regional
anesthesia must be carefully evaluated as a
matter of risk versus benefit
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Slide 20
Regional Anesthesia - Principles

Neurotoxicity
 Evidence suggests that local anesthetics can be
myotoxic and neurotixic
 Usually associated with long term catheter
placement and infusion pumps
 Unintentional direct injection into the nerve
sheath can cause nerve damage.
 Unintentional direct needle penetration of the
nerve can cause damage
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Slide 21
Regional Anesthesia - Principles

CNS Toxicity
 Muscle twitching
 Visual disturbances
 Tinnitus
 Light-headedness
 Tongue and lip numbness
 Extreme anxiety, screaming, and impending
death
feelings
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Slide 22
Regional Anesthesia - Principles

CNS Toxicity
 As blood concentrations increase S/SX progress
• Generalized tonic - clonic convulsions
• Coma
• Respiratory arrest
• Death
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Slide 23
Regional Anesthesia - Principles

Cardiac Toxicity
 Arrhythmias
and eventual collapse
 Agents with longer duration of action are the
culprit
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Slide 24
Regional Anesthesia - Principles

Blocked Extremities (Risk Factors)
 Neurological Function
 Splinting
 Compartment Syndrome
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Slide 25
Regional Anesthesia - Principles
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Neurological Function Assessment
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Lower Extremities (Distal Checks)
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Slide 26
Regional Anesthesia - Principles

Neurological Function Assessment
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Upper Extremity Neurological Check
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If you can’t remember anything, note sensory deficit
comparing good to bad and note prior to block
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Slide 27
Regional Anesthesia - Principles

Local anesthetics(Risk mitigation)
 Standard monitoring with audible O₂ saturation
tone
 O₂ supplementation
 Slow, incremental injection(5ml every 10-15sec)
 Initial injection of local “test dose” observe HR >
10 beats/min, BP> 15mmHg, or T-wave
decrease
 Pretreatment with benzodiazepines increase
seizure threshold
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Slide 28
Regional Anesthesia - Principles

Local anesthetics(Risk mitigation) cont.
 Patient either awake or sedated, but still able to
communicate
 Resuscitation equipment and drugs available
 If seizure occur, airway maintenance, O₂ and
seizure termination with propofol (25-50mg)
 If cardiovascular collapse, ACLS
 Intralipid 20% 1ml/kg every 3-5 minutes up to
3ml/kg in conjunction with ACLS treatments
Military Advanced Regional Anesthesia and Analgesia, TABLE 3-2
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Slide 29
Regional Anesthesia - Principles

Local anesthetics(Risk mitigation) cont.
 “test dose” 10ml of regional agent with
epinephrine 1:400,000 (0.5ml 1:000 in 10ml)
• Aspirate for blood, inject 1ml
• If resistance felt, reposition repeat aspirate
 Inject 3-5ml of local with epinephrine
1:400,000
 Transfer to “clean” agent syringe
• Aspirate every 3-5ml
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Slide 30
Regional Anesthesia - Principles

Conduction of Nerve Impulse
 Locating Nerves with Stimulation
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Slide 31
Regional Anesthesia - Principles

Conduction of Nerve Impulse
 Locating Nerves with Stimulation
 Advancing needles (1.2mA
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to 0.5mA)
Slide 32
Regional Anesthesia - Principles

Putting it Together Nerve Stimulation
 Motor as a Proxy
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Slide 33
Regional Anesthesia - Principles

Agenda
 Review physiology of nerve impulse conduction
 Identify equipment
and preparation to provide
peripheral nerve blocks
 Identify types of local anesthetic agents,
characteristics, and risk factors
 Indentify techniques of risk mitigation in
performance of regional blocks
 Identify nerve stimulation theory
JSOMTC, SWMG(A)
Slide 34
Regional Anesthesia - Principles

References
 Military Advanced Regional Anesthesia and
Analgesia Ch. 2 – 4
 Pathophysiology for the Health Professions 4th
Edition Ch. 6 p.126
 Basis Guide to Anesthesia for Developing
Countries, Volume 1, Daniel D. Moos
(International Federation of Nurse
Anesthetists, ifna-int.org)
JSOMTC, SWMG(A)
Slide 35
QUESTIONS ?
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Slide 36