Iontophoresis for Local Anesthesia
Iontophoresis for Local Anesthesia
ABSTRACT & COMMENTARY
Synopsis: Iontophoresis of lidocaine provides an effective alternative to topical or injected local anesthesia for office pediatric surgical procedures.
Source: DeCou JM, et al. Iontophoresis: A needle-free, electrical system of local anesthesia delivery for pediatric surgical office procedures. J Pediatr Surg 1999;34:946-949.
Thirty-four children undergoing a minor office surgical procedure (mostly excision of skin lesions or abscess drainage) were given local anesthesia with lidocaine-epinephrine delivered locally by iontophoresis. Sixty percent of patients who were able to rate procedural pain and 84% of parents rated procedural pain as none to mild. Seven patients required additional local anesthetic given through the previously anesthetized area. One child developed a small superficial burn. Iontophoresis is an effective and safe alternative method of local anesthesia for pediatric surgical procedures.
Comment by Howard A. Pearson, MD, FAAP
As has been previously commented upon in Pediatric and Adolescent Medicine Reports, there is increasing awareness and concern about pain experienced by infants and children undergoing invasive procedures including circumcision, spinal tap, bone marrow aspiration, venipuncture, and other injections. This has led to increasing use of topical local anesthetics (5% lidocaine-priolcaine or EMLA cream). Although this is usually fairly effective in reducing procedural-related pain, it must be applied at least 60 minutes before the procedure for maximum effect. Local anesthesia administered by subcutaneous needle injections, because of the child’s fear of needles, commonly increases anxiety and the discomfort associated with injections may be as bad as the procedure.
Iontophoresis is a needlefree method for local anesthesia in which a small electrical current is used to draw ionically charged 2% lidocaine-epinephrine into the skin and underlying subcutaneous tissue. Previous studies have compared iontophoresis with EMLA local anesthesia for dermatologic procedures and considered the anesthesia obtained by iontophoresis to be superior.1,2
DeCou and colleagues, pediatric surgeons from Greenville, S.C., evaluated the efficacy and safety of iontophoretic local anesthesia in a group of children 3 months to 15 years of age (mean, 6.8 years) who had minor surgical procedures in their office. They used a commercially available delivery system (Phoresor II Auto manufactured by Iomed Inc., Salt Lake City, Utah) consisting of a programmed nine-volt battery-driven power supply and two electrodes. Positively charged lidocaine and epinephrine molecules applied to the positive (delivery) electrode are attracted to the negative (dispersive) electrode placed at a distance and are drawn into the skin. The maximal current is 4 mA. The mean iontophoresis time was 16.1 minutes (7-30 minutes). Thirty-eight procedures were performed on 34 consecutive patients—mostly excision of skin lesions or drainage of an abscess. Procedure-related pain was judged to be none to mild by more than 80% of parents, physicians, and nurses. Ninety-five percent of patients who had had previous conventional local anesthesia described iontophoresis as superior, and three-fourths said that they would use it again. Eighteen percent of patients required additional local anesthesia but this was not associated with significant pain when injected through the previously anesthetized area. Fifty percent of patients experienced a tingling sensation at the point of electrode placement. One patient developed a small, superficial burn adjacent to the dispersive electrode. DeCou et al found that the mean time for iontophoresis was more compatible with office practice than the hour required for EMLA anesthesia.
Iontophoresis has been successfully used for two years in the ambulatory hematology/oncology center at the Yale-New Haven Children’s Hospital and is preferred over EMLA application by almost all of our patients—even those who usually applied EMLA at home before coming to the clinic. It is effective for venipuncture and lumbar punctures but less effective for bone marrow aspirations. It does not anesthetize the periosteum but reduces the pain of subsequent needle injections of lidocaine. Although most older children do not find the frequent tingling sensation uncomfortable, some infants and small children find it to be discomforting and express objections to the sensation.
References
1. Greenbaum SS, Bernstein EF. Comparison of iontophoresis of lidocaine with a eutectic mixture of lidocaine and prilocaine (EMLA) for topically administered local anesthesia. J Dermatol Surg Oncol 1994;20: 579-583.
2. Irsfeld S, et al. Dermal anaesthesia: Comparison of EMLA cream with iontophoretic local anaesthesia. Br J Anaesthiol 1993;71:375-378.
Iontophoresis for local anesthesia:
a. is effective in preventing pain associated with bone marrow aspiration.
b. is possible because lidocaine/epinephrine have negative ionic charges.
c. must be applied for a minimum of 60 minutes.
d. is considered to be superior to conventional local anesthesia by patients who have experienced both methods.
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