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Regional Anesthesia
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Regional Anesthesia
, Ultrasound Guided Regional Anesthesia, Regional Block Anesthesia, Nerve Block
See Also
Local Skin Anesthesia
Field Block
Hematoma Block
Digital Block
Point of Care Ultrasound
(
POCUS
)
Indications
Regional Anesthesia to allow for procedures (in place of
Procedural Sedation
)
Severe localized pain control (e.g.
Femur Fracture
)
Contraindications
Anticoagulation
is NOT a contraindication to Nerve Blocks
However, best to perform block at compressible site
Infection overlying injection site
Serial
Neurologic Exam
required
Patient unable to report pain or
Paresthesia
s at injection site (suggests nerve injection)
Altered Mental Status
or sedation
Types
Head and Neck
Images
Occiput
Greater Occipital Nerve Block
Ear
Ear Nerve Block
Regional Anesthesia for the Forehead
Supraorbital Nerve Block
Supratrochlear Nerve Block
Regional Anesthesia for the Central Face
Infraorbital Nerve Block
Regional Anesthesia for the Anterior Mandible
Mental Nerve Block
Lips
Lower Lip Nerve Block
Upper Lip Nerve Block
Teeth
Inferior Alveolar Block
Periapical Block
Neck
Superficial Cervical Plexus Nerve Block
Interscalene Brachial Plexus Block
Types
Trunk (
Chest
Wall including Ribs)
Erector Spinae Plane Block
Serratus Anterior Nerve Block
Intercostal Nerve Block
Types
Arm
Images
Neck and upper chest
Superficial
Cervical Plexus Block
(anterolateral neck and clavicle)
Shoulder
Suprascapular Nerve Block
Axillary Nerve Block
Upper arm and elbow
Interscalene Brachial Plexus Block
(includes
Shoulder
)
Supraclavicular
Brachial Plexus Block
(entire arm distal to
Shoulder
)
Forearm
and hand
Infraclavicular
Brachial Plexus Block
(includes elbow)
Axillary
Brachial Plexus Block
Elbow
Median Nerve Block at Elbow
Radial Nerve Block at Elbow
Ulnar Nerve Block at Elbow
Wrist
See
Ultrasound-Guided Wrist Block
Median Nerve Block at Wrist
Radial Nerve Block at Wrist
Ulnar Nerve Block at Wrist
Types
Leg
Images
Hip
Femoral Nerve Block
Fascia Iliaca Block
Lateral Femoral Cutaneous Nerve Block
Lower leg (below knee)
Popliteal Sciatic Nerve Block
(peroneal nerve and tibial nerve)
Ankle
See
Ultrasound-Guided Ankle Block
Regional Anesthesia of the Anterior Ankle
Superficial Peroneal Nerve Block
Deep Peroneal Nerve Block
Saphenous Nerve Block
Regional Anesthesia of the Posterior Ankle
Posterior Tibial Nerve Block
Sural Nerve Block
Complications
Nerve injury with persistent
Paresthesia
s
Local
Anesthetic
System Toxicity (LAST)
Intravascular injection of
Anesthetic
results in
Seizure
s,
Arrhythmia
s or
Cardiac Arrest
Calculate toxic dose levels in advance of injection, and stay well below these levels
Highest risk with
Bupivacaine
(lowest risk with
Ropivacaine
)
Ropivacaine
toxicity presents with neurologic findings
Bupivacaine
toxicity presents with
Cardiac Arrhythmia
s
Treated with
Intralipid
(20% IV fat emulsion) 1.5 ml/kg bolus, then 0.25 ml/kg/min until stable
Airway management and treat
Seizure
s with
Benzodiazepine
s
Exam
Identify region of
Anesthesia
needed (and most appropriate Nerve Block to adequately cover that region)
Focused peripheral nerve exam
Sensory Exam
Motor Exam
Preparation
Informed Consent
Intravenous Access
and
Intralipid
available
See LAST Syndrome under complications
Ultrasound
High frequency linear probe is preferred
Stand-off pad (or copious
Ultrasound
gel) may be needed in regions where peripheral nerve is superficial
Pre-scan with
Ultrasound
and identify needle insertion site
Nerve will appear as starry night within annular structure (or honey comb)
Consider marking the insertion site and landmarks
Ultrasound
significantly lowers complication rate (nerve injury, intravascular injection)
Cover probe with sterile
Ultrasound
probe cover (or transparent dressing such as
Tegaderm
)
Needles
Images
Blunt tip needles or Tuohy Needles (preferred over cutting needles)
Blunt tip needles allow for better tactile feedback at fascial planes and less risk of nerve injury
Needle sizes
Gauge: 25 to 27 gauge (up to 18-22 gauge in some cases)
Length: 1.5 inches (up to 3 inches in some cases)
Anesthetic
: Amides
Mepivacaine
1 to 1.5%
Maximum dose: 4 mg/kg
Onset: 10-20 minutes
Duration: 45 to 90 minutes up to 3 hours
Lidocaine
1 to 2%
Maximum dose: 4 mg/kg
Onset: 5-10 minutes
Duration: 30 to 60 minutes (longer with
Epinephrine
)
Bupivacaine
(
Marcaine
,
Sensorcaine
) 0.25% or 0.5%
Onset: 5 minutes (up to 15-30 minutes)
Duration: 2 to 4 hours (up to 6 hours, esp. when combined with
Epinephrine
)
Max bolus dose: 2 mg/kg (some guidelines use maximum of 2.5 mg/kg)
Weight >=75 kg (165 lb): 60 ml of 0.25% (2.5 mg/ml) or 30 ml of 0.5% (5 mg/ml)
Avoid in pregnancy (increased bioavailability, crosses placenta)
Always confirm not intravascular (withdraw first) as risk of lethal
Arrhythmia
s (
Ventricular Fibrillation
)
See
LAST Reaction
Less risk of systemic absorption when combined with
Epinephrine
Ropivacaine
0.2 to 0.5%
Preferred agent in Regional Anesthesia (decreased LAST toxicity risk)
Decrease dose in liver disease, malnourishment,
Critical Illness
Single bolus
Onset: 10-20 minutes
Duration: 6 to 14 hours
Maximum Dose: 3 mg/kg of 0.5 % (5 mg/ml)
Weight 50 kg (110 lb): Maximum 30 ml of 0.5% (1 bottle of
Ropivacaine
)
Weight 60 kg (132 lb): Maximum 36 ml of 0.5%
Weight 70 kg (154 lb): Maximum 42 ml of 0.5%
Weight 80 kg (176 lb): Maximum 45-48 ml of 0.5%
Weight 90 kg (198 lb): Maximum 45-54 ml of 0.5%
Weight >=100 kg (220 lb): Maximum 45-60 ml of 0.5% (up to 2 bottles of
Ropivacaine
)
Continuous infusion
Maximum: 0.5 mg/kg/h of 0.2% (2 mg/ml)
Weight 40 kg: Maximum 10 ml/h of 0.2% (2 mg/ml)
Weight 50 kg: Maximum 12 ml/h of 0.2% (2 mg/ml)
Weight >=56 kg: Maximum 14 ml/h of 0.2% (2 mg/ml)
References
Reardon and Martel (2020) Regional Anesthesia for Acute Care Conference, attended 12/11/2020
https://stabroom.com/
Anesthetic
: Esters (Indicated in amide
Anesthetic
allergy)
Pontocaine
0.25%
Maximum dose: 1.5 mg/kg
Onset: 15-30 minutes
Duration: 2 to 3 hours
Chloroprocaine 1-2%
Maximum dose: 6 mg/kg
Onset: 15-30 minutes
Duration: 30 to 60 minutes
Anesthetic
volume
Volume is more important than concentration for block efficacy
Blocks most commonly fail for lack of adequate volume
Best to dilute
Anesthetic
to lower concentrations and higher volume (better efficacy, lower toxicity)
Based on Nerve Block type
Plane blocks (e.g.
Fascia Iliaca Block
) fills a virtual plane between muscle or fascial layers
Requires larger volumes of
Anesthetic
Peripheral Nerve Blocks
Relatively smaller volumes of
Anesthetic
are used compared with plane blocks
The injection is localized around the target nerve and
Ultrasound
demonstrates the proximity
Skin preparation
Apply topical antiseptic to region of needle insertion site
Chlorhexidine (Hibiclens, preferred)
Povidone-
Iodine
(Betadine)
Drape surrounding skin
Technique
Ultrasound
-Guided Block
Background
Ultrasound
guided Nerve Blocks are preferred over external landmarks and peripheral nerve stimulation guidance
Ultrasound
reduces failed Nerve Block, neurovascular injury and shortens procedure time
Abrahams (2009) Br J Anaesth 102(3):408-17 [PubMed]
Lewis (2015) Cochrane Database Syst Rev (9):CD006459 +PMID:26361135 [PubMed]
Ultrasound
probe
High Frequency linear probe (5 to 12 MHz) is used for most Nerve Blocks
Prepped with sterile cover as above
Held in non-dominant hand
Some needles may be magnetized for better visualization on
Ultrasound
Ultrasound
probe beam angle settings may be adjusted/angled to remain perpendicular to needle
Allows for better needle visualization
In-Plane Approach (preferred if anatomy allows)
Needle enters on one side of probe long-axis (parallel to the probe)
Needle may be followed along its entire length
Requires fine control of probe and needle due to narrow width of the
Ultrasound
beam (3 mm)
Out-Of-Plane Approach
Needle enters at center of probe (perpendicular to the probe)
Requires probe to fan with the needle insertion to follow the distal needle tip
Absolute needle tip may be difficult to distinguish from other positions on the needle shaft
Needle insertion
Gradually advance needle, making slight angle adjustments as approaching target
Advance needle until adjacent but not within the nerve
Slightly withdraw needle if
Paresthesia
s or pain is experienced
Anesthetic
injection
Withdraw first to confirm that needle is not intravascular
First inject a small volume of
Anesthetic
adjacent to nerve (visualize on
Ultrasound
)
Observe for
Anesthetic
spread on
Ultrasound
(tissues separate)
Lack of
Anesthetic
spread may indicate intravascular injection
Withdraw needle if
Paresthesia
or pain occurs
Wait to inject at new location until symptoms resolve
Inject at several sites around the nerve
Results in encasing the nerve in a wide ring of fluid
Evaluation of Nerve Block efficacy
Test the region of Nerve Block over the subsequent 10-15 minutes
Wait to initiate procedure until adequate
Anesthesia
achieved
Resources
Local
Anesthetic
s: Clinical Pharmacology and Rational Selection
http://www.nysora.com/regional-anesthesia/foundations-of-ra/3492-local-anesthetics-clinical-pharmacology-and-rational-selection.html
Upper Extremity Nerve Blocks (AAFP, Includes diagrams and videos)
https://www.aafp.org/afp/2020/0601/p654.html
References
Eicken and Rempell (2016) Crit Dec Emerg Med 30(4):3-11
Reardon and Martel (2020) Regional Anesthesia for Acute Care Conference, attended 12/11/2020
https://stabroom.com/
Swaminathan and Stone in Herbert (2019) EM:Rap 19(3): 3-4
Yurgil (2020) Am Fam Physician 101(11):654-64 [PubMed]
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