Supraclavicular Nerve Block Periprocedural Care
- Author: Alma N Juels, MD; Chief Editor: Meda Raghavendra (Raghu), MD more...
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- An ultrasound machine with a 8-15 MHZ straight or curved-array probe and sterile ultrasound gel is needed. The higher frequency transducer is used since it is such a superficial block.
- A needle, usually a 21-gauge or 22-gauge 80-mm block needle, is needed. Use an insulated stimulating needle that can be connected to a nerve stimulator if any doubt exists regarding the nature of any structure that may look like the nerves. These needles tend not to be very echogenic. Specific echogenic needles can be used for ultrasound guided blocks, but the difference tends to be minimal.
- A nerve stimulator can be used, if wanted in adjunct to ultrasound images or if an ultrasound is available. Use a 21-gauge or 22-gauge insulated needle, with the nerve stimulator set at 1-1.5 mA,* pulse frequency of 1 Hz and pulse duration of 0.1 msec. Attach the needle to the nerve stimulator and place the grounder on patient.
- Local anesthetic (see below): If you have a good image, 20mL is all you need. Increasing the volume increases the chance of phrenic nerve paralysis. Local anesthetic with a 25-gauge or 27-gauge needle is also needed for a skin wheal before block needle insertion.
- Lipid emulsion and resuscitation equipment must be available. The patient needs to have basic monitoring with 3-5 lead EKG, NIBP, and pulse oximetry.
- Sterile prep such as ChloraPrep and sterile ultrasound gel: In the authors’ institution, the authors use a sterile Tegaderm to place over the ultrasound probe; they then place the sterile ultrasound gel the Tegaderm. A printer can be attached to the ultrasound to get still images for the chart.
For surgical anesthesia in adults, a single shot of 30mL of 1.5% Mepivacaine plain provides close to immediate (5 min) to 2-3 hrs of surgical analgesia. For longer surgical anesthesia up to 3-4 hrs, 1:400,000 epinephrine is added to the solution. The block completely resolves about 2 hrs later. If a longer block is needed, adding Tetracaine at 2mg/mL (0.2%) prolongs the block to 4-6 hrs.
For longer postoperative analgesia, 0.25% Ropivacaine or Bupivacaine is used and should provide more than 12 hr of pain relief. The onset will be delayed from 5 min to about 20 min and providesr both perioperative and postoperative pain control. A combination of both can be used.
Monitoring & Follow-up
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- Pneumothorax is the biggest concern with a supraclavicular block. The incidence has decreased substantially with ultrasound guidance. Onset of symptoms may take up to 24 hours.
- Hematoma can occur. To reduce the chance of a hematoma, avoid multiple needle insertions and apply firm pressure after removing needle. Consider risk/benefit in coagulopathic patients.
- Nerve injury is always a possibility with nerve blocks. Avoid contact with the nerve bundles and advance the needle slowly. Stop when a "pop" is felt entering the nerve sheath. Do not inject if high pressure is felt. Do not inject if patient experiences pain. Readjust the needle when the above scenarios are experienced. Most of the time, the needle needs to be withdrawn slightly. This is an extremely rare complication.
- Once again, toxicity can occur with any block. The clinician needs to prevent intravascular injection. Aspirate every 3-5 mL. Inject slowly to avoid injecting local anesthetics into smaller vessels and lymphatics that have been punctured during needle insertion.
- Infection: To avoid, use strict aseptic technique.
- Horner syndrome
- Phrenic nerve palsy (this is less likely than with an interscalene block)
- One study showed 50% diaphragm paralysis with a supraclavicular block compared with 100% with an interscalene block. This study was with the sole use of a nerve stimulator. With the ability to localize the brachial plexus better with an ultrasound and the need for lower volumes, the incidence of diaphragm paralysis is significantly less.