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Iontophoresis for myringotomy or ear procedures under local anesthesia

last modified on: Fri, 02/09/2024 - 10:28

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What is iontophoresis?

Iontophoresis is a process in which ionized chemical substances are applied to the surface of the body and introduced into the tissue using electrical current. The anesthetic will act in tissue along the path of least resistance.

Purpose

Iontophoresis can be used to safely and easily anesthetize the TM using the method below. Different methods of iontophoresis are employed to anesthetize the ear canal. Iontophoresis does not involve any injection, is nearly painless, and is well tolerated by children. 

Indications

Iontophoresis may be useful for placement of a myringotomy with or without tympanostomy tube or for use children to facilitate foreign body removal.

Steps

  1. It is critical to fully examine the TM to ensure there is no perforation, do not proceed if there may be a perforation. Confirm the patient does not have any allergy to lidocaine or local anesthetics.
  2. Mix 1 mL 4% lidocaine (topical) with 1 mL 1:1000 epinephrine in a 3 cc syringe and mix in the syringe and warm it in your hands. Do not use any premixed solution. Do not use any other local anesthetic, as these have been proven to be cochleotoxic.
  3. Connect the grounding pad to the lead and apply to the ipsilateral upper arm
  4. Once the solution is warmed to body temperature, turn the ear upwards with the head in a comfortable position. Instill the 2% lidocaine with 1:2000 epinephrine mixture down the ear canal into the ear to avoiding trapping bubbles, and fill up just to the cartilaginous EAC. Do not overfill the EAC.
  5. Insert the electrode into the solution without touching the bony ear canal and hold it in position
  6. Turn on the ionesthetizer and set the timer to 10 minutes (up to 15), 0.5 mA and press start
  7. Wait until the unit beeps to remove the electrode
  8. Turn the ear down to drain out the anesthetic and wait 5 minute to test anesthesia. If anesthesia is incomplete then test after another 5 minutes

Anesthesia of the TM should last about 1.5 hours.

The iontophoresis unit is kept in the clean utility room on the right in a locked glass cabinet.

References

Gillespie CA, Swanson GC, Johnson CM, Strom CG. Inner ear lidocaine concentrations following iontophoresis. Laryngoscope. 1980 Nov;90(11 Pt 1):1845-51.

Yen DM, Murray MT, Puchalski R, Gould AR, Ansley J, Ow RA, Moss JR, England LJ, Syms CA 3rd. In-Office Tympanostomy Tube Placement Using Iontophoresis and Automated Tube Delivery Systems. OTO Open. 2020 Feb 24;4(1):2473974X20903125. doi: 10.1177/2473974X20903125. PMID: 32133434; PMCID: PMC7040928.