Local anaesthesia (numbing medicine) that is directly applied to the skin can provide pain control for repair of skin lacerations

Background: Pain control during suturing of torn skin is generally achieved by injecting medication into the skin (infiltration) to numb the area. This injection itself may cause pain, but topical anaesthetics are applied directly to the skin and are painless to administer. Cocaine was one of the first anaesthetics to be successfully applied topically. Concerns over adverse effects of cocaine, its potential misuse and the administrative burden of dispensing a controlled substance led to the development of cocaine-free topical anaesthetics. Multiple cocaine-free topical anaesthetics have been found to provide effective anaesthesia for repair of dermal lacerations.

Study characteristics: The evidence is current to December 2016. We included in this review 25 randomized controlled trials involving 3278 participants. Studies included both adults and children. Fifteen of the included trials used self-reporting of pain intensity by trial participants to determine the effectiveness of local anaesthetics.

Key results: Study results suggest that directly applying local anaesthetics to the skin is an effective, non-invasive way of providing pain control during suturing or stapling of skin lacerations. Study findings on the efficacy of individual topical anaesthetics were limited by study design, and data on the efficacy of each topical agent were obtained mostly from single trials. Researchers reported no serious side effects following the use of cocaine-containing or cocaine-free topical anaesthetics. The overall broadly comparable effectiveness of cocaine-free topical anaesthetics for skin laceration repair brings into question the necessity to include cocaine as a component of local anaesthetic solutions. The small number of trials in each comparison group and the range of outcome measures assessed prevented pooling and quantitative analysis of data for all but the single outcome of pain intensity.

Additional studies are necessary to directly compare the effectiveness of different formulations of topical anaesthetics. Our review was limited to pain control for repair of superficial lacerations, and our results might not be generalizable to deeper lacerations or more complex procedures performed on intact skin. Further research is needed to strengthen the evidence and to overcome the weakness of the included studies.

Quality of the evidence: The overall quality of the evidence was low owing to limitations in study design, ways that studies were carried out (implementation), imprecision of results and high probability of selective data reporting. Most of the trials that compared infiltrated and topical anaesthetics were at high risk of bias, and this was likely to influence measured effects.

Authors' conclusions: 

We have found two new studies published since the last version of this review was prepared. We have added these studies to those previously included and have conducted an updated analysis, which resulted in the same review conclusions as were presented previously.

Mostly descriptive analysis indicates that topical anaesthetics may offer an efficacious, non-invasive means of providing analgesia before suturing of dermal lacerations. Use of cocaine-based topical anaesthetics might be hard to justify, given the availability of other effective topical anaesthetics without cocaine. However, the overall quality of the evidence according to the GRADE system is low owing to limitations in design and implementation, imprecision of results and high probability of publication bias (selective reporting of data). Additional well-designed RCTs with low risk of bias are necessary before definitive conclusions can be reached.

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Background: 

Topical local anaesthetics provide effective analgesia for patients undergoing numerous superficial procedures, including repair of dermal lacerations. The need for cocaine in topical anaesthetic formulations has been questioned because of concern about adverse effects, thus novel preparations of cocaine-free anaesthetics have been developed. This review was originally published in 2011 and has been updated in 2017.

Objectives: 

To assess whether benefits of non-invasive topical anaesthetic application occur at the expense of decreased analgesic efficacy. To compare the efficacy of various single-component or multi-component topical anaesthetic agents for repair of dermal lacerations. To determine the clinical necessity for topical application of the ester anaesthetic, cocaine.

Search strategy: 

For this updated review, we searched the following databases: Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 11), Cumulative Index to Nursing and Allied Health Literature (CINAHL; 2010 to December 2016), Embase (2010 to December 2016) and MEDLINE (2010 to December 2016). We did not limit this search by language or format of publication. We contacted manufacturers, international scientific societies and researchers in the field. Weemailed selected journalsand reviewed meta-registers of ongoing trials. For the previous version of this review, we searched these databases to November 2010.

Selection criteria: 

We included randomized controlled trials (RCTs) that evaluated the efficacy and safety of topical anaesthetics for repair of dermal laceration in adult and paediatric participants.

Data collection and analysis: 

Two review authors independently assessed trial quality and extracted data. We contacted study authors for additional information when needed. We collected adverse event information from trial reports. We assessed methodological risk of bias for each included study and employed the GRADE approach to assess the overall quality of the evidence.

Main results: 

The present updated review included 25 RCTs involving 3278 participants. The small number of trials in each comparison group and the heterogeneity of outcome measures precluded quantitative analysis of data for all but one outcome: pain intensity. In two pooled studies, the mean self-reported visual analogue scale (VAS; 0 to 100 mm) score for topical prilocaine-phenylephrine (PP) was higher than the mean self-reported VAS (0 to 100 mm) score for topical tetracaine-epinephrine-cocaine (TAC) by 5.59 points (95% confidence interval (CI) 2.16 to 13.35). Most trials that compared infiltrated and topical anaesthetics were at high risk of bias, which is likely to have affected their results. Researchers found that several cocaine-free topical anaesthetics provided effective analgesic efficacy. However, data regarding the efficacy of each topical agent are based mostly on single comparisons in trials with unclear or high risk of bias. Mild, self-limited erythematous skin induration occurred in one of 1042 participants who had undergone application of TAC. Investigators reported no serious complications among any of the participants treated with cocaine-based or cocaine-free topical anaesthetics. The overall quality of the evidence according to the GRADE system is low owing to limitations in design and implementation, imprecision of results and high probability of publication bias (selective reporting of data). Additional well-designed RCTs with low risk of bias are necessary before definitive conclusions can be reached.

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