Reduction of topical anesthetic onset time using ultrasound: a randomized controlled trial prior to venipuncture in young children.

Background: Ultrasound treatment prior to topical anesthetic application has been shown to speed anesthesia onset by enhancing anesthetic penetration into the skin.

Objective: To evaluate a low-frequency ultrasound device to facilitate absorption of topical anesthetic in young children who require venipuncture.

Methods: This was a prospective controlled comparison of analgesic effect of a 5-minute application of liposomal lidocaine cream after ultrasound treatment, with a 30-minute application of liposomal lidocaine cream, in children aged 3 to 7 years undergoing venipuncture. Children rated the pain of the venipuncture using the Wong-Baker FACES Pain Rating Scale (FACES) (0 = no pain, 10 = maximal pain), and parents rated their child's pain using a 100-mm (0 = no pain, 100 = maximal pain) visual analogue scale (VAS). Venipuncture skin sites were evaluated for effect immediately posttreatment, and at 24 to 72 hours post phlebotomy.

Results: Seventy subjects were enrolled: the first 10 patients comprised a pilot series, receiving the ultrasonic treatment and liposomal lidocaine cream; the next 60 subjects were randomized, including 29 allocated to the ultrasound treatment group, and 31 randomized to the 30-minute control treatment with liposomal lidocaine cream. Demographics were similar between the two groups. Mean child's FACES scale results were similar: Ultrasound group 4.78 (95% CI; 3.06, 6.52), CONTROL group 4.32 (95% CI; 2.82, 5.82) (P = 0.72); and mean parent VAS scores were also the same: Ultrasound: 19.1 (95% CI; 10.3, 27.8), CONTROL: 23.2 (95% CI; 14.7, 31.7) (P = 0.87). Skin effects immediately after ultrasound were limited to minor redness in 9/39 children and significant redness in 2/29 patients.

Conclusion: Ultrasound treatment speeds time of onset of liposomal lidocaine cream anesthesia in young children undergoing venipuncture. Side effects were mild in our population.