The purpose of this study was to compare the efficacy of eutectic mixture of local anesthetics (EMLA) cream to 4% liposomal lidocaine cream (LMX4) for managing pain during sharp debridement of wounds.
Sharp debridement involves the use of a scalpel or scissors to assist with removal of infected or necrotic tissue; this method is preferred for deep wounds, when there is a large amount of tissue to be removed, or when significant infection is present with risk of sepsis , and has been found to decrease time to healing over other forms of debridement. However, sharp wound debridement has been associated with pain, and minimizing pain is essential, as undertreated pain causes distress.
Eutectic mixture of local anesthetics (EMLA) is an emulsion of 2.5% lidocaine and 2.5% prilocaine. EMLA is effective in providing dermal anesthesia for IV cannulation in adults and children, lumbar puncture, sharp debridement of leg ulcers and decubitus ulcers, among other wound types. Lidocaine is an effective agent for providing anesthesia in a variety of procedures such as intravenous cannulation procedures of the oral cavity, prostate biopsy, episiotomy, and wound debridement. Lidocaine comes in different preparations and strengths. 4% liposomal lidocaine is a newer lidocaine preparation which facilitates a more rapid onset of anesthesia. Both EMLA and LMX4 have been available for several years, and much of the research on efficacy was conducted as these agents were released.
Few studies were found that compared EMLA to 4% lidocaine or 4% liposomal lidocaine. Of those studies found, EMLA cream was superior to 5%, 4%, and 2% lidocaine in studies of topical anesthesia for oral and nasal mucosa. Other studies found no significant difference between EMLA and 4% lidocaine gel; or between 4% liposomal lidocaine and EMLA when used for laser procedures and skin micro-needling. In addition, EMLA cream was reported to be more expensive than some of the lidocaine preparations. No studies were found comparing EMLA cream to 4% liposomal lidocaine cream for managing pain during sharp debridement.
Methods:
This study was a randomized, controlled, double-blinded, cross-over trial of EMLA cream compared to 4% liposomal lidocaine (LMX4) for the management of pain during sharp wound debridement. It was approved by the facility’s Institutional Review Board.
Forty patients referred to the wound center for sharp debridement of a venous, arterial, or lymphedemic wound, or pressure ulcer that required more than one debriding were recruited for this study. People with diabetes were included if there was no neuropathy. People who were taking analgesics were considered if they had not used an analgesic in the 24 hours prior to their appointment.
Each participant was randomly assigned to treatment order. An RN applied the anesthetic agent to the wound using the method prescribed by the manufacturer, and covered the site with an occlusive dressing. Lidocaine remained covered for 15 minutes and EMLA for 30 minutes prior to debridement. Debriding was performed according to wound type and location, and the wound was dressed as per standard care.
Participants were asked at both appointments to rate their wound pain using a visual analog scale with a range of 0 to 10 at four points during the procedure: prior to topical anesthetic application, before debridement started, during debridement, and following debridement. They were also assessed for any complications from the cream or the procedure. Following the second debridement, they were asked if the anesthetic applied at the first debridement (T1) or the second debridement (T2) provided better pain relief.
Results:
Thirty-two participants completed the study. Forty-one percent believed LMX4 provided better pain relief than EMLA (28%). Repeated measures MANOVA revealed a significant effect of time (λ = .369, F(3,28) = 15.964, p = < .001). Mean pain rating was higher at T1 than at T2 for corresponding assessment points. Pain during debridement at T1 was statistically significantly higher than pain at any other point except during T1 admission and T2 debridement. There was also a significant effect of drug by drug order (LMX4 applied at Time 1 or EMLA applied at Time 1) (λ = .796, F(1,30) = 7.677, p = .010); those who had EMLA at T1 reported less pain at T2 with LMX4, but there was no difference for those who had LMX4 at T1.
Conclusion:
This was the first known study to compare EMLA to LMX4 for sharp debridement. We found no statistically significant difference between EMLA and LMX4 in managing pain associated with sharp wound debridement. There were, however, significant differences in pain ratings for the four points in time at which pain was assessed for both topical anesthetics, and for the topical anesthetics by the order in which they were given. Participants believed that LMX4 provided better pain relief than EMLA. Five participants experienced burning on application of EMLA, a common complication associated with this agent (Claeys et al., 2010; Evans & Gray, 2005).
An unexpected finding was that participants who received EMLA first reported significantly lower pain during the second treatment when they were given LMX4. One possible explanation is that participants who received EMLA first, as a result of having more intense pain initially, experienced the decrease more acutely. It is also possible that the burning sensation experienced by some of the participants on application of EMLA may explain the difference.
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