II. Indications
- Regional Anesthesia to allow for procedures (in place of Procedural Sedation)
- Severe localized pain control (e.g. Femur Fracture)
III. Contraindications
-
Anticoagulation is NOT a contraindication to Nerve Blocks
- However, best to perform block at compressible site
- Infection overlying injection site
- Limb Compartment Syndrome suspected
- Allergy to medication components
- Serial Neurologic Exam required
- Patient unable to report pain or Paresthesias at injection site (suggests nerve injection)
- Altered Mental Status or sedation
IV. Types: Head and Neck
- Images
- Occiput
- Ear
- Regional Anesthesia for the Forehead
- Regional Anesthesia for the Central Face
- Regional Anesthesia for the Anterior Mandible
- Lips
- Teeth
- Neck
V. Types: Trunk (Chest Wall including Ribs)
- Erector Spinae Plane Block
- Serratus Anterior Nerve Block
- Intercostal Nerve Block
VI. 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
- Wrist
VII. Types: Leg
- Images
- Hip
- Lower leg (below knee)
- Popliteal Sciatic Nerve Block (peroneal nerve and tibial nerve)
- Ankle
VIII. Complications
- Nerve injury with persistent Paresthesias
-
Local Anesthetic System Toxicity (LAST Reaction)
- Intravascular injection of Anesthetic results in Seizures, Arrhythmias 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 Arrhythmias
- Treated with Intralipid (20% IV fat emulsion) 1.5 ml/kg bolus, then 0.25 ml/kg/min until stable
- Airway management and treat Seizures with Benzodiazepines
IX. Exam
- Identify region of Anesthesia needed (and most appropriate Nerve Block to adequately cover that region)
- Focused peripheral nerve exam
X. 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
-
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 Arrhythmias (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)
- Maximum: 0.5 mg/kg/h of 0.2% (2 mg/ml)
- References
- Reardon and Martel (2020) Regional Anesthesia for Acute Care Conference, attended 12/11/2020
- Mepivacaine 1 to 1.5%
-
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
- Pontocaine 0.25%
-
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
- Plane blocks (e.g. Fascia Iliaca Block) fills a virtual plane between muscle or fascial layers
- Volume is more important than concentration for block efficacy
- Skin preparation
- Apply topical antiseptic to region of needle insertion site
- Chlorhexidine (Hibiclens, preferred)
- Povidone-Iodine (Betadine)
- Drape surrounding skin
- Apply topical antiseptic to region of needle insertion site
XI. 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
-
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 Paresthesias 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
- Observe for Anesthetic spread on Ultrasound (tissues separate)
- 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
XII. Resources
- Local Anesthetics: Clinical Pharmacology and Rational Selection
- Upper Extremity Nerve Blocks (AAFP, Includes diagrams and videos)
XIII. 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
- Swaminathan and Stone in Herbert (2019) EM:Rap 19(3): 3-4
- Yurgil (2020) Am Fam Physician 101(11):654-64 [PubMed]
Images: Related links to external sites (from Bing)
Related Studies
Concepts | Therapeutic or Preventive Procedure (T061) |
English | regional block anesthesia, Regional block anesthesia |