Article, Dermatology

The loop technique: a novel incision and drainage technique in the treatment of skin abscesses in a pediatric ED

a b s t r a c t

Objective: This study assesses outcome in pediatric patients with skin abscess using the LOOP compared to the standard incision and drainage (I&D) with packing method.

Methods: This retrospective study used ICD-9 codes to identify pediatric patients aged 0 to 17 years with a skin abscess presenting to a level I pediatric trauma emergency department (ED). Patients requiring surgical debride- ment were excluded; as were patients with abscesses on the face, scalp, hands or feet. The primary outcome was failure rate, defined as those requiring admission, Intravenous antibiotics, or repeat drainage.

Results: Over a 1-year period there were 233 Pediatric abscesses identified: 79 cases (34%) treated with the LOOP technique and 154 cases with standard I&D (66%). The overall mean age of patients was 6.2 yrs: children in the LOOP group were younger than those in the standard group, 4.4 vs 7.1 years respectively (P = .001). Abscess location also differed between the two groups; however they had a similar Gender distribution and mean temperature. Of the cases identified by chart review, clinical outcome could be assessed in 143 patients (61%): 52 (36%) patients with LOOP vs 91 (64%) with I&D. Failure rate was 1.4% in the LOOP group and 10.5% in the standard I&D (P b .030).

Conclusion: There was a significant difference in failure rate between the LOOP and the standard I&D groups. A prospective randomized trial is needed to confirm these results, but this novel technique shows promise as an alternative to I&D with packing in the management of skin abscesses in pediatric ED patients.

Introduction

Skin abscesses and other soft tissue infections remain one of the most common patient afflictions presenting to the emergency department. Overall, the incidence of skin and soft tissue infections in US emergency departments has tripled from 1993 to 2005 and now exceeds 3.4 million cases annually [1]. With the recent spread of community-acquired methicillin-resistant staphylococcus aureus (ca-MRSA), communities report prevalence rates of 53% to 80% for these drug-resistant organisms [2-4]. With so much effort being spent on producing more antibiotics, little resources are utilized to better treat skin abscesses. While antibiotics are often prescribed in the treat- ment of skin abscesses, proper incision and drainage of the abscess re- mains the mainstay of treatment [3-5]. Since the 1970s, incision and drainage with packing has been the standard emergency department

? Grant Support: None.

?? Author Disclosure Statement: None.

? Abstract presented at the American College of Emergency Physicians Annual Scientif-

ic Assembly in Chicago Illinois, October 2008.

* Corresponding author. Tel.: +1 407 237 6329; fax: +1 407 649 3083.

E-mail addresses: [email protected] (J.G. Ladde), [email protected] (S. Baker), [email protected] (C.N. Rodgers), [email protected] (L. Papa).

¹ Tel.: +1 407 237 6329; fax: +1 407 649 3083.

technique [6,7], although alternatives using various drains, needle aspi- ration, or ultrasound guidance have been reported with varying degrees of success [8,9].

Most skin abscesses require incision and drainage, but packing with iodoform gauze can be painful and can dislodge, making a second procedure more likely. This can be especially problematic for pediatric patients who may require sedation and in whom caring for packing can be difficult. The LOOP technique offers a suitable alternative that eliminates the need for packing. No study to date compares this technique with standard packing in the pediatric emergency department population.

The purpose of this study is to assess outcomes using the LOOP tech- nique versus standard incision and drainage with packing to treat sim- ple skin abscesses presenting to a pediatric emergency department.

Methods

Study design, setting and population

This was a retrospective cohort study of pediatric patients aged 0 to 17 years old. The study was approved by institutional review board of the XXXXXXXX with exemption of written informed consent. No specif- ic patient identifying information was shared. This study was conducted at a level I pediatric trauma and tertiary care center with an annual

http://dx.doi.org/10.1016/j.ajem.2014.10.014

volume of over 50000 patient visits. The community served by this hos- pital has a 80% prevalence rate for ca-MRSA.

Study protocol

Patients with a skin abscess were identified using ICD-9 codes from January to December 2007. Three separate emergency physi- cians reviewed over 900 charts using a standard data extraction form. Inter-rater reliability of extraction assessed in 5% of charts was 100%. We included children with an abscess who had their abscess incised and drained in the ED. Patients requiring Surgical debridement were excluded, as were patients with abscesses on the face, scalp, hands or feet. Demographic data along with abscess location, presenting temperature, and use of sedation and antibiotics were recorded. We reviewed follow-up medical records and made phone call follow-ups to assess for out- come measures.

LOOP technique

The LOOP technique provides a novel technique to drain skin ab- scesses. Several studies in the surgical literature have described this technique and its safety when performed by surgeons, usually in the op- erating room [8,10,11]. The LOOP technique is performed using a stan- dard 11-blade, skin prep solution, local anesthesia such as lidocaine, standard hemostats, and one or more vascular ties. The skin cleansed and draped in the usual fashion before lidocaine (1% or 2%) is injected locally with a small bore needle to provide anesthesia (Fig. 1a). Intrave- nous sedation may be provided to patients who are unable to tolerate only local anesthesia. An initial incision (approximately 0.50 cm) is made at one end of the abscess. A hemostat is introduced and used to break up loculations within the abscess. Then, the hemostat is inserted into the wound and used to tent skin opposite the first incision, and a second incision is made at its tip (Fig. 1b). Once the second incision is made, the wound is thoroughly irrigated under high pressure with ster- ile irrigant. The vessel loop tie is grasped by the protruding end of the

Fig. 1. a, Step 1 in Loop drainage technique. Prepare the area and administer local anesthesia. Make a central incision and use a hemostat to break up loculations within the abscess. The abscess may be irrigated now or after the vessel loop is placed. b, Step 2 in LOOP drainage technique. Use the hemostat to tent the skin near the farthest edge of the abscess cavity, and make a second incision over the tip of the hemostat. c, Step 3 in LOOP drainage technique. Once the second incision is made, the wound is thoroughly irrigated under high pressure with sterile irrigant. Push the hemostat through the new incision, and use it to grab the vessel loop and pull it through the abscess cavity. d, Step 4 in LOOP drainage technique. Pull vessel loop through the abscess cavity. e, Step 5 in LOOP drainage technique. Tie the vessel loop, using a finger or hemostat to keep it loose over the surface of the skin. f, Step 6 in LOOP drainage technique. Appearance of final vessel loop placement.

Fig. 2. Multiple LOOP drainage technique. The figure demonstrates multiple LOOP drainage for an extensive abscess. Larger abscesses may require more than one loop to span most of the abscess cavity.

hemostat and pulled through the abscess cavity and out the first incision (Fig. 1c and d). It is then loosely hand-tied (Fig. 1e and f). In some instances, a second or more loops are placed if the abscess is large or irregularly-shaped (Fig. 2). The loop is removed 7 to 10 days after placement.

Outcome measures

The primary outcome measure was treatment failure, defined as the need for repeat incision and drainage, intravenous antibiotics, admis- sion, or surgical treatment within 10 days.

Data analysis

Data were analyzed using descriptive statistics including propor- tions, means with 95% confidence intervals. Univariate analyses includ- ed Fisher exact test, contingency coefficient, and Mann-Whitney U test. Comparison of Failure rates between the two treatment groups was per- formed using Fisher exact test. Adjusted odds ratios for clinical factors were calculated to adjust for potentially confounding factors using lo- gistic regression analysis. Significance was set at 0.05. All analyses were performed using the statistical software package PASW 17.0 (IBM Corporation, Somers, NY).

Patients treated for abscess during the study period N=235

No Method of drainage specified

N=2

LOOP

(Intervention) N=79

I & D (Standard Treatment)

N=154

Follow -up available N=51 (65%)

Follow-up available N=91 (59%)

Fig. 3. Flow chart. Flow chart showing patients in each of the two drainage groups.

Results

We identified 235 children with abscesses during the 12-month study period. We excluded 2 patients because method of drainage could not be determined, and we excluded 91 patients whose outcome could not be determined by phone interview or record review. Fig. 3 de- scribes the selection of the included cohort. There were 142 cases avail- able for final analysis: 91 cases had standard incision and drainage (I&D) (64%) and 51 cases (36%) were treated with the LOOP technique. There were no significant differences in age (P = .15) or gender (P = .34) in those who had outcome available versus those who did not. The overall median age of patients was 2.0 years (IQR 1.4-12.0) with a range from 5 months to 18 years. There was a significant difference in age between the I&D and the LOOP groups, with a median age of 6.0 (IQR 1.6-15.0) in the I&D group and 1.8 (IQR 1.3-3.0) in the LOOP group. Patient char- acteristics in each group are provided in Table. Children in the LOOP group were more likely to receive sedation (65% vs 35% of I&D, P b

.001). Abscesses occurred on the buttocks more frequently in the LOOP group than the standard I&D group (63% vs 28%) (P = .003). The median age of children with an abscess on the Torso was 2.0 (IQR 0.7-3.8), on the Extremities was 6.5 (1.8-14.3), on the Buttock or Groin was 1.9 (1.3-7.8), and on the Head or Neck was 1.8 (1.1-15.8).

Treatment failure occurred in 16.5% of those in the I&D group and in 3.9% of those in the LOOP group (P = .03) (Fig. 4a). The location of the abscesses relative to treatment failure was found to be highest in the re- gion of the head and neck in the I&D group and highest in the buttock/ Groin area for the LOOP group (Fig. 4b). Adjusted odds ratios were calcu- lated and results shown in Fig. 5. Factors significantly associated with treatment failure after adjusting for other factors were drainage method 7.13 (1.17-43.5) and location of the abscess 1.42 (1.04-1.93). The use of the LOOP technique was associated with significantly fewer treatment failures.

Discussion

Despite trends in the prevalence of ca-MRSA and antibiotic choices, the treatment of skin abscesses has not changed significantly in the last 60 years. While incision and drainage remains the most common method of treating skin abscesses, it was not until recently that alterna- tives to packing with gauze have appeared in the literature. While there is data to suggest that incision and drainage without packing is acceptable, it has not been widely adopted [13]. Romolo et al described how needle incision drainage using ultrasound guidance proved inadequate compared with traditional incision and drainage in the emergency department [9].

Previous studies describe the use of the LOOP technique in surgical patients with abscesses. Tsoraides, et al described this technique and its utility in pediatric patients with abscesses treated in the operating room under general anesthesia; five percent of the 115 patients de- scribed in this retrospective study had loop technique failure [10]. Ladd et al describes a retrospective series of 128 children at two institu- tions who were in an observation unit or who were outpatients; many were treated under general anesthesia. They found no failures [11]. Ours is the first study describing the use of the LOOP technique by emer- gency physicians. Additionally, this study is the largest study comparing the LOOP technique with traditional incision and drainage with packing to treat skin abscesses.

With the emergence of ca-MRSA, innovative ways of treating skin ab- scesses have become necessary. Our study population comes from a community in which there is a 80% reported prevalence of community- acquired MRSA in simple skin abscesses; we no longer perform routine cultures of abscesses. Uniquely, while other studies have shown higher failure rates with ca-MRSA abscesses, our results show great promise with the LOOP technique in areas where there is a high prevalence of ca-MRSA. As evidenced by a nearly eight-fold higher failure rate in chil- dren treated with traditional incision and drainage with packing, this

Table

Description of patient characteristics in the I&D vs LOOP group

	I&D, n = 91 (95% CI)	LOOP, n = 51 (95% CI)	P
Median age in years (IQR) [range]	6.0 (1.6-15.0) [range 6 mo-18 y]	1.8 (1.3-3.0) [range 5 mo-16 y]	b.001
Gender (% female)	51 (56%) [46%-66%]	27 (53%) [39%-67%]	.73
Admission	4 (4%) [0%-9%]	2 (4%) [0%-9%]	.67
Previous history of abscess	1 (1%) [0%-3%]	3 (6%) [0%-13%]	.13
Antibiotics prescribed at discharge	84 (92%) [87%-98%]	41 (80%) [69%-92%]	.06
Location of abscess Head and neck	10 (11%) [4%-18%]	2 (4%) [0%-9%]	.003
Torso	6 (7%) [1%-12%]	2 (4%) [0%-9%]
Extremities	47 (52%) [41%-62%]	15 (29%) [16%-42%]
Buttocks/groin Temperature (?F) (+- SD) {range}	28 (31%) [21%-40] 99.1 (+-1.4) {range 97.0-103.7} [98.8-99.4]	32 (63%) [49%-76%] 99.7(+-1.9) {range 96.8-104.2} [99.2-100.3]	.11
Sedation (%)	19 (21%) [12-29%]	36 (71%) [58-84%]	b.001
Treatment failure	15 (17%) [9-24%]	2 (4%) [0-9%]	.03

Fig. 4. a, Bar graph comparing treatment failure between the 2 groups. Comparison of treatment failure between standard I&D versus the LOOP technique. Bars represent 95% CI. b, Bar graph comparing treatment failure between the 2 groups by abscess location. Comparison of treatment failure between standard I&D versus the LOOP technique by location of abscess. Bars represent 95% CI.

Fig. 5. Adjusted odds ratios for factors potentially associated with treatment failure. Factors significantly associated with treatment failure after adjusting for other factors were drainage method 7.13 (1.17-43.5) and location of the abscess 1.42 (1.04-1.93).

technique may offer an alternative to this standard regimen in the treatment of uncomplicated skin abscesses in pediatric patients follow- ing further study.

In our particular institution, the LOOP technique is utilized by attending physicians, residents in both pediatric and emergency medi- cine, fellows, and physician extenders. This procedure requires an equivalent amount of dexterity and experience as the traditional tech- nique to perform successfully. It is relatively simple to learn, making widespread utilization accomplishable.

In addition, while the use of packing in certain anatomical areas such as the perineum may preclude success, use of the LOOP allows for sim- plified care as it is stabilized in the wound and should not displace. What once was only cured by a painful and large wound with repeat visits can now be performed with two small incisions with a single follow-up visit. Location of the abscess likely played a role in the physi- cian’s choice to perform the LOOP. This is evidenced by more abscesses on the buttocks, groin and torso in the LOOP group than in the standard I&D group (63% vs 28%)(P = .003). This further supports the need for a randomized controlled trial.

Limitations

Our results should be interpreted in the context of several limita- tions. First, it is possible that the retrospective nature of the data biases the results. Because the choice of LOOP vs. standard I&D with packing was at the discretion of the treating physician, it is possible that patients better suited for one technique received that treatment. Confounding treatments, such as sedation and use of antibiotics were not controlled for in this study and was at the discretion the treating emergency physician. Both groups received similar rates of antibiotic treatment and were probably affected equally. Furthermore, previous studies have shown that antibiotic choice has little effect on a properly drained abscess [12]. Sedation was, however, used more frequently in the LOOP group. While sedation could offer a more complete drainage of abscess material given better patient tolerance of a painful procedure, the use of

sedation was typically utilized in Younger children. The mean age of those who received sedation was 2.9 (95% CI 1.9-3.9) versus 8.0 (95% CI 6.7-9.3)(P b .001). Whether the LOOP technique is more painful could not be ascertained from this study. However, analysis of those patients treated with sedation demonstrated no greater outcome than those who were not sedated.

Some patients were lost to follow-up; inclusion these patients may have impacted our results. The limited sample size and retrospective nature of the study makes it possible that subtle differences between the two groups were not identified. Many of these potential biases could be eliminated during a randomized, prospective study.

Conclusion

In this retrospective review, abscesses treated with the novel LOOP technique had significantly fewer treatment failures than those treated with standard I&D with packing, although differences in baseline characteristics and confounding treatment variables could account for these differences. A prospective randomized trial is needed to confirm these results, but this novel technique shows promise as an alternative to I&D with packing in the management of skin abscesses in pediatric patients presenting to the emergency department.

References

AJEM