A 5-year-old boy is brought to the emergency department after sustaining a laceration of the left lower extremity. Physical examination shows an isolated 2-cm lesion extending through the dermis. EMLA cream is applied prior to suturing.

The surgeon should wait for how many minutes before suturing the laceration?

(A) 5 minutes
(B) 10 minutes
(C) 20 minutes
(D) 30 minutes
(E) 60 minutes

The correct response is Option E.

Because EMLA cream reaches its peak efficacy approximately 45 to 60 minutes after initial application, the surgeon should wait for one hour before suturing the laceration. Studies show that EMLA cream is superior for anesthesia of simple extremity wounds and results in optimal anesthesia in open wounds after approximately 60 minutes. Cumulative sum (CUSUM) analysis has been used to confirm the minimal effective application time.

EMLA cream, a eutectic mixture of local anesthetics, contains lidocaine 5% and prilocaine 5%. Following topical application of EMLA cream, the affected site should be covered with an occlusive dressing.

References
1. Friedman PM, Fogelman JP, Nouri K, et al. Comparative study of the efficacy of four topical anesthetics. Dermatol Surg. 1999;25:950-954.
2. Maddi R, Horrow JC, Mark JB, et al. Evaluation of a new cutaneous topical anesthesia preparation. Reg Anesth. 1996;15:109-112.
3. Zempsky WT, Karasic RB. EMLA versus TAC for topical anesthesia of extremity wounds in children. Ann Emerg Med. 1997;30:163-166.