The LSUHSC New Orleans
Emergency Medicine Interest Group

Presents

The Student Procedure Manual


Emergency Department Anesthesia

(Infiltration and Neuro Blocks)

by Chris Gaffga

Contraindications
Use of Epinephrine
Choice of Anesthetic
Recommendations
Complications of Local Anesthetic
General Guidelines for Treatment of Systemic Toxicity
-Respiratory Depression
-Seizures
-Cardiovascular Complications
Topical Anesthetics
-Topical Jelly of Lidocaine
-Benzocaine
-TAC
-LET
General Procedure for Wound Infiltration
General Procedure for Nerve Block
Complications

Contraindications

  1. Previous reaction to local anesthetic. Ask questions
    about this to determine whether the reaction was a true allergic reaction, a vasovagal response (bradycardia and syncope without anaphylaxis or hives), or a problem with neuritis after a nerve block (neurogenic pain that usually spontaneously resolves).
  2. Liver disease, heart disease- R/O amide-based anesthetics (i.e. do not use Lidocaine, Mepivacaine, Prilocaine, Bupicacine, Etidocaine)
  3. Previous use of MAO inhibitors- R/O use of epinephrine
  4. Most anesthetics will reduce healing in wounds. Use carefully with slow healing wounds like leg ulcers

Use of Epinephrine
Epinephrine will:

*Epinephrine will often come premixed in a Lidocaine or other cartridge. Know what you are giving the patient, especially if you are working near an extremity.

*Local vasoconstriction can result from accidental intravascular injection. As you inject, watch for blanching. Effect can be reversed by administering 0.5 - 5.0 mg phentolamine. Other effects of intravascular administration of lidocaine include ringing in the ears and a strange taste in the patient's mouth.

Choice of Anesthetic

These are some commonly used anesthetics for wound repair. For dosage information on other drugs, consult a pharmacology manual.

Commonly Used Anesthetics
Agent
Lidocaine
Prilocaine
Bupivacaine
Conc. (for infiltration) 0.5 - 1.0% 0.5 - 1.0% 0.25%
Adult dose 300mg (500mg w/ epi.) 500mg (600mg w/ epi.) 175mg (225 w/ epi.)
Pediatric dose 4.5mg/kg (7mg/kg w/ epi.) 7mg/kg (9mg/kg w/ epi.) not for peds. use
Duration 1-2 hours 15-45 mins 4-8 hours

Recommendations

Complications of Local Anesthetic

*Be prepared to monitor and treat the following.

Safer-> Etidocaine >Bupivacaine >Lidocaine ->Less safe

*Watch for the following signs/symptoms as you give the injection. If you see any of the following, ask the patient to breathe rapidly to blow off CO2:

Warning Signs of Systemic Toxicity

  1. Tinnitus, numbness of tongue, lightheartedness, (drowsiness, with Lidocaine only)- This is usually first indication of systemic toxicity; happens at about 4 microgram/mL plasma
  2. Visual disturbances- Indicates a plasma concentration of about 6 micrograms/mL
  3. Muscle twitching, convulsions, coma, apnea- Indicates plasma concentration about 8 micrograms/mL

*Prepare for further treatment of respiratory depression that may follow (See below).

General Guidelines for Treatment of Systemic Toxicity

Topical Anesthetics

General Procedure for Wound Infiltration

  1. Use 10 mL syringe, 27 gauge needle
  2. To access the subcutaneous tissue place the needle in the wound edge if possible.
  3. Once in the skin aspirate the syringe
  4. Placement of the drug
  5. Numbing over a large field

See Basic Suturing for more information on wound infiltration

General Procedure for Nerve Block

  1. Use 25 or 27 gauge, short beveled needle with 10 mL
    syringe for digital or distal blocks.
  2. Use 23 or 25 gauge, short beveled needle with 30 mL
    Syringe for proximal blocks.

Note differences vs. infiltration procedure.

Procedure

  1. Swab skin with alcohol wipe
  2. Locate and identify landmarks, including nearby arteries
  3. Insert the needle parallel to the nerve fibers
  4. Nerves can be located exactly by eliciting paresthesia (a radiating "jolt" when the nerve is touched)
  5. After getting paresthesia, pull the needle out I mm and inject anesthetic.
  6. If you don't pull far enough out you can inject into the nerve sheath; the extra volume injected inside the sheath of a small nerve can compress the nerve and cut off its blood supply. Injection into the sheath will be a VERY sharp, radiating pain.
  7. Nerve block depends on getting very close to small nerves. If you are not sure that you got the "jolt" of paresthesia use a larger amount of anesthetic because it has to diffuse through tissue. Do not exceed the maximum in the dose range.
  8. Wait 30 minutes before deciding the block was not successful

Complications

 


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