Expanding the use of Topical anesthesia in

wound management: sequential layered application of topical lidocaine with epinephrine

Slava V. Gaufberg MD^a,*, Michael J. Walta MD^b, Tom P. Workman MD^a

^aDepartment of Emergency Medicine, The Cambridge Hospital, Cambridge Health Alliance, Division of Emergency Medicine,

Harvard Medical School, Boston, MA 02139, USA

^bDepartment of Internal Medicine, Cambridge Health Alliance, Harvard Medical School, Boston, MA 02139, USA

Received 4 April 2006; revised 1 November 2006; accepted 2 November 2006

Abstract

Topical anesthesia eliminates the need for injection of anesthetic. Most studies on the use of topical anesthesia were done on children, using 3 active ingredients (lidocaine, epinephrine, tetracaine, or tetracaine, adrenaline, cocaine) for relatively small wounds of the face and scalp.

Objectives: To demonstrate that topical anesthesia is effective and safe in adults of all ages and for larger wounds, using a preparation with 2 active ingredients, topical lidocaine and epinephrine (TLE). Methods: One hundred patients were enrolled in a randomized controlled trial, with 50 in each group. The study group received TLE using a unique method of bsequential layered application.Q The control group received 2% lidocaine infiltration anesthesia. Patients rated the pain from the application of anesthesia and from suturing, using a 0 to 10 visual analog pain scale. Follow-up interviews were conducted to assess for complications and to rate patients’ wound repair experience.

Results: Patients in the study group reported significantly less pain from TLE application, with 66% reporting no pain vs 0% reporting no pain from the infiltration in the control group ( P b .001). There was no difference in pain during wound repair between the 2 groups ( P ~ .59). On follow-up, 95% of patients contacted in the TLE group rated their experience in regard to pain as bexcellent,Q compared to 5% of patients in the control group ( P b .001).

Conclusion: Topical lidocaine and epinephrine bsequential layered applicationQ is an effective, safe, and less painful method of anesthesia for a wide variety of lacerations. Patients recall their experience with this technique very favorably.

D 2007

Introduction

More than 10 million lacerations are treated annually in EDs in the United States. Pain relief during wound repair is a

* Corresponding author. Tel.: +1 617 665 1712.

E-mail address: [email protected] (S.V. Gaufberg).

primary goal of the emergency physician. There are a number of methods available for wound anesthesia, includ- ing topical anesthesia, infiltration of the wound, field or nerve block, hematoma block, and conscious sedation [1].

The main advantage of topical anesthesia is the elimination of injection of anesthetic. It effectively elimi- nates pain from injection, distortion of infiltrated wound

0735-6757/$ - see front matter D 2007 doi:10.1016/j.ajem.2006.11.013

tissues, and decreases the risk of needle-stick injury to the operator [2].

However, the use of topical anesthesia has been limited. Most previous studies have used preparations that contain 3 active ingredients, either lidocaine, epinephrine, tetracaine (LET), or tetracaine, adrenaline, cocaine (TAC). LET has been studied extensively in children [1,3], but its use has been largely confined to small wounds (b2 cm) on the face and scalp [2,4,5] or superficial wounds [6]. Anesthetic failure has been reported to exceed 5% on extremities [6,7]. The use of TAC has declined because of concerns about the potential for severe toxicity from systemic absorption of cocaine [1,8].

We therefore undertook a study to investigate the use of Topical anesthetics in adults for a large variety of wounds and lacerations. Because we planned to use topical anesthesia for large wounds that require a significant amount of anesthetic, we used a preparation with only

2 active ingredients, topical lidocaine and epinephrine (TLE), to limit the potential for toxicity [9]. Because the traditional method of applying topical anesthetic to the wound surface does not provide sufficient anesthesia to deep wounds, we developed a Novel method of bsequential layered applicationQ of TLE.

We hypothesized that sequential layered application of TLE would allow us to achieve anesthesia equal to that of infiltration with lidocaine, minus the pain caused by infiltration.

Methods

Study design

We performed a prospective, randomized controlled trial of the effectiveness of TLE anesthesia using the sequential layered application technique. Patients presenting with lacerations to the ED were enrolled in either the study group (using topical anesthetic) or the control group (injection anesthetic). The primary outcome measured was pain reported by the patient during application of anesthetic and during wound repair using a 0-to-10 visual analog pain scale. Informed consent was obtained from all subjects. The study was approved by the institutional review board.

Study setting and population

The setting of the study was a community teaching hospital ED with an Annual patient volume of 30 000 serving an urban population.

The study population consisted of 100 adults greater than 18 years old, having lacerations in need of suturing.

The following exclusion criteria were applied: allergy to lidocaine or epinephrine, altered mental status, inability to verbalize pain according to the visual analog pain scale, pregnancy, age younger than 18 years.

Study protocol

Subjects in both groups were given anesthesia before wound irrigation and cleaning.

In the study group, all lacerations were anesthetized with TLE solution, containing 5% lidocaine and 0.025% epi- nephrine. A novel technique of bsequential layered appli- cation,Q developed by Slava V. Gaufberg, MD, was used for the application of TLE. A piece of cotton just large enough to cover the laceration and 2 mm of surrounding skin was soaked with TLE. The soaked cotton was placed on the wound for 10 to 15 minutes, then removed. A second, similarly sized piece of cotton soaked in TLE was packed deeper inside the wound for 10 to 15 minutes, then removed. For deeper wounds, a third layer of cotton soaked with TLE may be packed deeper into the wound in the same fashion (see Fig. 1). The wound was presumed to be anesthetized and ready for suturing when 3-mm-wide or greater area of vasoconstrictive pallor formed along all wound edges. The wound was then probed with the teeth of surgical forceps to assure anesthesia along the entire length and depth of the wound. If an area of the wound was inadequately anesthe- tized, more TLE was applied to the wound until adequate anesthesia was achieved.

In the control group, infiltration anesthesia with buffered 2% lidocaine solution with 8.4% sodium bicarbonate solution 9:1 was performed using the standard technique.

The wound was then probed with the teeth of surgical forceps in the same fashion as in the study group. If an area of the wound was inadequately anesthetized, more lidocaine

Fig. 1 A small piece of TLE-soaked cotton is packed on the wound surface. Vasoconstrictive pallor develops, indicating anes- thesia. Another piece of cotton is packed deeper and remains for 10 to 15 minutes. This is repeated until the wound is fully anesthetized.

Fig. 2 Percent reporting pain during application of anesthetic.

Table 1 Characteristics of control and study group

	Control group, n	Study group, n	P
Total	50	50
Age (y)			.75
18-30	20	19
31-50	21	22
51-70	6	8
N70	3	1
laceration length (cm) b1	1	0	.75
1-2	5	3
2-3	14	16
3-5	19	22
N5	11	9
Laceration depth (cm) b0.5	13	14	.95
0.5-2.0	31	29
2.0-4.0	6	7
Laceration location			.10
Scalp	7	8
Face	5	10
Lower extremity	9	4
Upper extremity	11	4
Hands	18	24

was infiltrated into the wound until adequate anesthesia was achieved.

Measurements

In each group, baseline characteristics including age of the subject, length and depth of the wound, location of wound, and time to achieve anesthesia were recorded. Information about the number of cotton layers and amount of TLE used in the study group was recorded.

The effectiveness of anesthesia was assessed by the patient immediately after the procedure using a 0-to-10 visual analog pain scale administered by third-party (a resident, nurse, or multilingual interpreter). The subject was instructed to assess the pain from the application of anesthesia (either from TLE application or lidocaine infiltration) and the pain from suturing the wound. These pain assessments were recorded immediately.

Table 2 Application of anesthesia

Control group Study group P

Time to achieve

anesthesia (min)
Range	1-12	20-40	b.001
Mean	5	29
Amount of lidocaine used (mg) Range	10-340	25-400	.90
Mean	124	135

Follow-up assessment 3 to 6 months later was made by ED volunteers (premed students) who asked patients whether they had encountered bany problem with wound healing, including infection,Q and then asked patients to rate their overall wound repair experience as bexcellent,Q bgood,Q bsatisfactory,Q or bunsatisfactory.Q

Data analysis

Data for all 100 patients were analyzed without any exclusion. Baseline characteristics and follow-up data were compared using v² tests. v² values were converted to P values using standard conversion tables. Pain scores were compared using Wilcoxon rank sum tests. The difference between means was used to construct 95% confidence intervals (CIs) around the difference in the mean pain scores between the study and control groups. P values of less than

.05 were considered significant.

Results

We enrolled 100 consecutive adult patients presenting for laceration repair. Fifty subjects were randomly enrolled in each group.

Baseline characteristics for the 50 patients in each group were similar (Table 1).

In the control group, time necessary for adequate infiltration anesthesia varied from 1 to 12 minutes, with a mean time of 5 minutes. The amount of lidocaine needed to achieve adequate anesthesia varied between 10 and 340 mg, with a median amount of 124 mg. For the study group, the time for the application of TLE necessary for adequate wound anesthesia varied from 20 to 40 minutes, with a mean time of 29 minutes. The time taken for TLE to achieve adequate anesthesia was significantly longer than for the control group ( P b .001). The number of application layers needed to achieve adequate anesthesia varied between 1 and

Table 3 Pain during application of anesthetic					Table 4 Effectiveness of anesthesia during wound repair
	Control	Study	P			Control group, n	Study group, n	P
	group, n	group, n			Visual analog			.59
Visual analog			b.001		pain scale
pain scale					0	42	4
0	0	33			1	6	4
1	4	16			2	2	2
2	6	1			3	0	0
3	9	0			4	0	0
4	10	0			z5	0	0
5	9	0			Mean	0.20	0.16

4, with a mean of 2.7. Twenty-six patients (52%) required 3 layers, 17 patients (34%) required 2 layers, and 5 patients (10%) required 4 layers of TLE. The amount of TLE needed to achieve adequate anesthesia varied from 25 to 400 mg of lidocaine, with a median amount of 135 mg (Table 2). The amount of lidocaine used in TLE application was compa- rable to that (mean 124 mg) in the control group ( P ~ .90).

6	5	0
7	2	0
8	2	0
9	1	0
10	2	0
Mean	4.34	0.36
Difference	3.98
between means
95% CI (range of	(4.60-3.36)
difference)

Pain during application of anesthetic and wound repair

During the application of anesthesia, patients in the control group reported significant pain from infiltration of lidocaine, with 21 patients (42%) reporting pain of 5 or greater. In the study group, 33 patients (66%) reported no

Fig. 3 Percent reporting pain during wound repair.

pain from the application of TLE. The remaining 17 patients reported mild pain, with no patients reporting a score greater than 2 (Fig. 2). The mean pain score for the control group is

4.34 vs a pain score of 0.36 in the study group ( P b .001), with a difference of 3.98 in the mean pain scores between groups. We are 95% confident that the difference between pain scores is between 4.60 and 3.36 (Table 3).

Difference

between means 95% CI (range of

difference)

0.04

(0.23 to -0.15)

During wound repair, effectiveness of anesthesia was similar in both groups. In the control group, 42 patients (84%) reported no pain from suturing, and no one reported a pain level above 2. In the study group, 44 patients (88%) reported no pain from suturing, and no patients reported pain scores greater than 2 (Fig. 3). In the control group, the mean pain score was 0.20 vs a pain score of 0.16 in the study group ( P ~ .59), with a difference of 0.04 in the mean pain scores between groups. We are more than 95% confident that there is no difference in the pain scores between the control and study groups during wound repair (Table 4).

Follow-up interview

We obtained follow-up interviews with 37 patients in the control group and 42 patients in the study group (Table 5). Patients in the TLE application group reported a better

Table 5 Follow-up interview after wound repair

Patients contacted

(% of total)

Recall of experience

(% of patients contacted) Excellent

Good Satisfactory Unsatisfactory

Difficulty with wound healing or infection

Control

group, n

37 (74%)

Study P

group, n 42 (84%)

b.001

2 (5%)

23 (62%)

10 (27%)

2 (5%)

0

40 (95%)

2 (5%)

0

0

0

overall experience than patients in the control group. A majority (95%) of patients contacted in the TLE application group rated their experience as bexcellent,Q as compared to only 5% of patients contacted in the control group. The difference in satisfaction between the 2 groups was significant ( P b .001). No patients in either group reported difficulty with wound healing or infection.

Discussion

Topical anesthesia for laceration repair has been prac- ticed for many years. Factors responsible for limiting its use include concern for toxicity, lack of optimal technique for application in large wounds, and increased time to achieve anesthesia.

Sequential layer application technique

In our study, adults of all ages with a wide variety of lacerations on various areas of the body achieved effective anesthesia using sequential layered application of TLE. Application of TLE was significantly less painful than the infiltration technique used in the control group. Overall, patients who received TLE reported a significantly better wound repair experience than patients receiving injectable lidocaine. No complications in wound healing or infection were reported during follow-up interviews in either group. Most of the topical anesthesia studies showed poor success on trunk and extremity wounds in comparison with scalp and face wounds [9-11]. However, in previous studies, application of anesthetic was limited to the surface of the wound [2-12]. We postulate that, as the circulation on the trunk and extremities is relatively poor compared to the face and scalp, local tissue absorption of single-layered topical anesthetic in these areas is limited. Using sequential layer application of topical anesthetic may overcome relatively

poor absorption in these areas.

Time to achieve anesthesia

The time taken to achieve adequate anesthesia for TLE is the major pitfall of this technique. Time ranged between 20 and 40 minutes, and 1 to 4 layers of TLE were required. Deeper lacerations requiring several layers are the most time- consuming. However, waiting 10 to 15 minutes for anes- thesia to take effect for each layer was arbitrarily used in this study. It is possible that this time could be reduced without compromising the effectiveness of anesthesia, although we did not evaluate this in the present study. Training ancillary staff, including Triage nurses, in the application of TLE might reduce the problems associated with longer applica- tion times [10,11]. Fully anesthetized patients would then be ready for wound repair by the ED physician.

bIs it worth the time?Q In our opinion, it is. The technique leads to the elimination of the following factors: painful injection, risk of hollow-bore needle injury, and distortion of

infiltrated wound tissue. It also shows the high rate of patient satisfaction. We feel this justifies the additional time spent on applying topical anesthesia.

Potential for toxicity

The generally accepted limit for the use of injectable lidocaine with epinephrine is 7 mg/kg [12,13]. We propose the same limit be used for TLE, although substantially less lidocaine is absorbed when used topically.

As such the limit for a 70-kg person would be: 70 x 7 = 490 mg, or 10 mL of the 5% solution that was used in this study. Therefore, the limit for 5% lidocaine solution would be 1 mL for every 7 kg of body weight. This imposes a practical limit on the size of lacerations that can be treated with this technique. The largest laceration treated in this study was 12 cm long in a 79-kg patient who needed a total of 8 mL of TLE (400 mg of lidocaine) to achieve good anesthesia.

Two percent lidocaine solution in control group was chosen over 1% solution to decrease the volume of injected solution and subsequent tissue distortion. Lidocaine without epinephrine was used for injection anesthesia in the control group to avoid excluding patients with lacerations on acral areas.

Limitations

Data collection and statistical analysis

Our study may be limited by the way in which primary data were collected. Background information on age, laceration depth, and laceration length was collected with respect to somewhat arbitrary ranges and placed into tables for statistical analysis. The effect was to break otherwise continuous variable into discrete variables. t-Test analysis would have been the preferred statistical method had these data been recorded on a continuous scale. It is impossible to know whether this had more than a nominal effect on our results and analysis.

Follow-up interview

When we obtained follow-up interview, we were unable to contact 26% of the patients from control group vs 16% from study group. This may weaken the follow-up comparisons between the groups, although it is difficult to know whether the subjects lost to follow-up were more prone to good or bad wound repair experiences.

Use on acral areas

It is generally accepted that epinephrine should not be injected in acral areas such as the fingers, toes, nose, penis, and ears. Such injection can theoretically cause vasospasm and threaten the viability of the part. However, recent studies suggest low risk of ischemic vasospasm when local

epinephrine is injected into acral areas [14,15]. Our study does not provide any additional information regarding this issue. We therefore cannot recommend that the technique described here be used on acral areas, although topical lidocaine-adrenaline-tetracaine preparations have been used safely on children with finger lacerations [16].

Conclusions

Topical anesthesia with only 2 active ingredients (lidocaine and epinephrine) using our sequential layered application technique is a highly effective and safe method of pain control for suturing a wide variety of lacerations. Patients graded their experience with this technique very favorably.

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