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Nine Myths About Wound Care
Does time to closure really influence infection risk? Do subcuticular sutures actually reduce scarring? Using an evidence-based approach, the authors clear up some common misconceptions about these and other issues in wound management.
By Marvin A. Wayne, MD, FACEP, and Adam J. Singer, MD, FACEP
Wherever wounds occur on the body, the fundamental goals of wound management are always the same: early closure, prevention of infection, and a cosmetically appealing and functional scar. All of the key steps in wound management are taken with these results in mind.
The number and variety of wounds seen by emergency department physicians justifies continued interest in wound care. The most recent figures provided by the National Center for Health Statistics in 2005 show that, of approximately 120 million emergency department visits, there were 12 million wounds, 7 million lacerations, 2.5 million abscesses, and 430,000 burns serious enough to be treated in the emergency department. Lacerations occur on many parts of the body, which often influences how they are treated. They most commonly occur on the upper extremities (38%), face (27%), and trunk (13%). About 11% occur on the lower extremities and 11% in the head and neck area.
Many myths about the management of wounds still abound. This article examines—and debunks—nine of the most common ones.
MYTH #1
WOUNDS SHOULD BE KEPT DRY
Until the mid-20th century, wounds were kept dry to avoid infection. It was also thought blisters healed faster when they were broken. However, studies in pigs during the 1960s showed that treating partial thickness wounds with occlusive dressings, which help create a moist environment, doubled the rate of reepithelization. Studies in humans during the same decade also seemed to confirm that occluded wounds healed faster.
Later studies confirmed the advantages of moist wound healing. A moist wound healing environment has been shown to help prevent cell dehydration and death, promote angiogenesis, and improve phagocytosis and growth factor elaboration. It also improves the rate of re-epithelialization, reduces pain, and improves the cosmetic outcome. Those who objected to the use of occlusive dressings argued that they would cause infection. However, most studies have not confirmed this suspicion. In fact, a meta-analysis of more than 3000 wounds covered with occlusive dressings or gauze demonstrated that wound infection rates were significantly lower with occlusive dressings: 2.6% of those with occlusive dressings became infected versus 7.1% of those with gauze dressings (p=0.05).
Reality Check: Infection rates are lower and healing is faster when wounds are kept moist.
MYTH #2
STERILE TECHNIQUE PREVENTS INFECTION
It may seem counterintuitive that anyone would question whether sterile technique prevents wound infection. However, a revealing study shows the effect of using caps and masks on infection rates. In this study, 442 lacerations were irrigated with chlorhexidine. A cap and mask were worn while repairing 239 lacerations and not worn while repairing the rest (203). The incidence of wound infection was 2.5% when clinicians wore caps and masks and 3.9% when they did not, with no statistically significant difference between the groups. Thus, caps and masks do not seem to prevent infection. Of course, common sense should prevail. A mask should be used when the practitioner has a respiratory infection and is sneezing or coughing.
Another study—a multicenter, single-blind, randomized study of 816 patients—looked at sterile versus nonsterile gloves as a factor in wound infections. Most of the wounds were sutured and 25% were treated with topical antibiotics. Ninety-seven percent were followed up within one week. In the sterile glove group, 6.1% of wounds developed infections versus 4.4% in the nonsterile glove group. Several other similar studies have come to the same conclusion.
Reality Check: The use of caps, masks, and sterile gloves is probably not necessary for the average laceration treated in the emergency department.
MYTH #3
FACIAL AND SCALP LACERATIONS SHOULD BE IRRIGATED
Although there is evidence that irrigation lowers infection rates in contaminated wounds created in animals, there is no evidence that irrigation is effective in clean, low-risk wounds in humans. Overall infection rates are 3% to 5% after traumatic laceration repair in the emergency department and are even lower in well-vascularized facial and scalp lacerations.
An observational study of 1923 wounds examined whether high-pressure irrigation is necessary in facial and scalp wounds. In this study, 1090 wounds were irrigated and 833 were not. Infection rates and cosmetic outcome of low-risk wounds were compared. (The cosmetic parameter was added because high-pressure irrigation might cause wound distortion that is difficult to correct.) The two groups compared were similar in terms of patient demographics and wound characteristics, including length of wounds, layers of closure, and use of antibiotics. The study revealed that infection rates were similar in patients whose wounds were irrigated (0.9%) and those whose wounds were not (1.4%). In terms of cosmetic outcome, 76% of the irrigated group achieved good results, compared to 82% of the nonirrigated group. Although the difference in cosmetic outcome was not statistically significant, there was definitely a trend favoring no irrigation (p=0.07).
Again, common sense should prevail: Dirty or highly contaminated wounds still require meticulous cleansing and irrigation.
Reality Check: High-pressure irrigation of low-risk facial and scalp lacerations of the type generally seen in the emergency department does not lower the incidence of infection but may result in a slightly less optimal cosmetic result.
MYTH # 4
SALINE SOLUTION IS A MORE EFFECTIVE IRRIGANT THAN TAP WATER
Somehow, the idea of running tap water over a wound seems less appropriate than irrigating it with saline solution. However, saline costs more than tap water and is not readily available outside the hospital. Is there any evidence that saline is more effective than tap water at preventing wound infections?
A randomized, controlled study of 530 wounds in pediatric patients treated in the emergency department compared wound infection rates. Saline was used is 271 patients; tap water was used in 259. While the baseline characteristics in both study groups were fairly similar, the group randomized to tap water irrigation had more hand lacerations, which tends to increase the infection rate. The results were as follows: 2.8% of the saline-irrigated group developed an infection versus 2.9% of the tap-water irrigated group. Other studies confirm these results.
Although saline appears to be no more effective than tap water in preventing infection, it is still commonly used in the United States at considerable expense to health care institutions. In other countries where saline is unaffordable, tap water is used. As long as the tap water is not contaminated, it seems to be effective.
Reality Check: Saline solution is no more effective in preventing wound infections than tap water.
MYTH #5
A RELATIONSHIP EXISTS BETWEEN THE TIME FROM INJURY TO CLOSURE AND WOUND INFECTION RATES
One of the oldest wound controversies concerns the length of the “golden period” of the wound. This period represents the time interval between wound injury and closure when closing the wound is still safe without significantly increasing the risk of infection. Some have recommended that wounds more than 6 to 12 hours old not be closed. Several studies have reached different conclusions based on the types of wounds and patients.
One of the largest studies was conducted in Jamaica, where many patients have dirty wounds and present relatively late to the emergency department. This observational study compared healing rates at 7 days, without infection, between wounds closed within 19 hours of injury and those closed after 19 hours of injury. The results are representative of other studies demonstrating that lacerations on the face, head, and neck can be safely closed even after 19 hours without increasing the risk of infection.
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| Location influences "golden period." Infection risk rises more rapidly with time to closure in wounds of the lower extremities and trunk. This calf wound, 5.5 hours old, was still free enough to be healed by primary closure. |
In contrast, studies show that lacerations over the lower extremities (see image above) and trunk have an increased risk of infection and nonhealing when closed after 19 hours from the time of injury. Thus, the golden period of the wound must be individualized based on patient characteristics and wound characteristics including, but not limited to, wound location.
Reality Check: For wounds on the face, head, and neck, there is no evidence that delayed closure results in an increase in the rate of wound infection. Wounds on the trunk, arms, and legs probably should not be closed after 6 to 12 hours.
MYTH #6
MAMMALIAN BITES TREATED WITH PRIMARY CLOSURE ARE MORE PRONE TO INFECTION
An observational study from 2000 looked at 145 patients with mammalian bites from dogs, cats, and humans (although not many human bites were included) treated with primary closure, with a mean time from injury to treatment of 1.8 hours. Fifty-seven percent of the bites were on the head and neck and 36% were on the extremities. Essentially, the infection rate was the same for patients with bite wounds (5.5%) and nonbite wounds (3% to 7%).
What about dog bites specifically (see images below)? In 1988, 96 patients with 169 wounds were studied in a randomized clinical trial. Of these, 92 wounds were randomized to suturing and 77 were left open. Most of the wounds were short and on the hands, and the average time from wound to treatment was 2.5 hours. No systemic antibiotics were given to any of the patients. The rate of infection in both groups of patients was approximately 8%. Because the cosmetic outcome of facial lacerations is so important and overall infection rates in this area tend to be low, most facial lacerations are sutured, regardless of whether they are caused by dog, cat, or human bites. When it comes to extremities, where infection rates are higher and cosmesis is less important, most small puncture wounds are not closed, large wounds are loosely closed, and patients are given oral antibiotics for prophylaxis.
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A role for every device. Sutures are the best choice for high-tension wounds like this child's dog-bite lacerations. |
Should antibiotics be given to prevent infection in patients with dog bites? In eight randomized studies reported in the 2001 Cochrane database, antibiotics clearly reduced infections in wounds caused by human bites but did not reduce infections caused by dog or cat bites. However, the study showed that regardless of the cause of the extremity bites, these wounds benefited most from prophylactic systemic antibiotics.
Reality Check: Facial lacerations (especially large ones) from any mammalian bite can be safely sutured. Studies confirm that antibiotics reduce wound infections caused by human bites on the extremities.
MYTH #7
SUTURES ARE THE BEST CLOSURE DEVICE FOR LACERATIONS
Sutures have been around longer than other closure methods. But what is the best or most appropriate method of closing wounds—sutures, staples, surgical tapes, or topical skin adhesives?
All of the available wound closure devices have a role in wound closure and each has its own advantages and disadvantages. Sutures are the time-honored method of closing wounds, but they have several drawbacks. They are painful to insert and painful to remove for the patient. They are also relatively expensive, carry a risk of a needle-stick injury for the provider, are time-consuming to put in, depend on the skill of the person doing the suturing, and cause greater tissue reactivity than other wound closure devices.
Another major disadvantage of sutures is that most require removal. Those left in the skin beyond seven days may cause ugly dots on either side of the wound. Fast-absorbing sutures may avoid the need for removal. On the other hand, sutures provide the most meticulous closure, the greatest tensile strength, and the lowest dehiscence rate. In general, sutures are the most appropriate wound closure device for complex and high-tension wounds and over areas where other devices may be inappropriate, such as the hair and mucous membranes.
Staples are excellent for scalp wounds. Other than topical antibiotics, no further dressings are required. Staples can be applied quickly with little training, have low tissue reactivity, are inexpensive, and carry a very low risk of injury to the physician. The disadvantages are that staples result in a less meticulous closure, may interfere with imaging, and require removal, which can be painful.
Surgical tape is inexpensive, has the lowest infection rates in animal models, can be placed quickly, is comfortable for the patient, and is the least tissue reactive of all wound closure devices. However, the tape often falls off, cannot get wet, cannot be used over hair, has low tensile strength, and can cause blisters. Surgical tapes can be used to reinforce wounds after removal of sutures or staples when the wound’s bursting strength is quite low.
Cyanoacrylate topical skin adhesives were first synthesized in 1949 and first used clinically in 1959. Their application is rapid, simple, painless for the patient, and relatively inexpensive. The material is a liquid monomer that polymerizes into a solid polymer on contact with tissue anions. It is applied topically and bonds the apposed wound edges. No removal is necessary because the topical adhesive sloughs off spontaneously in 5 to 10 days as the skin renews itself. Fingernail bed injuries can be closed with a topical adhesive as well as hand lacerations that are to be splinted over the next 5 to 10 days.
Topical skin adhesives are extremely valuable for fragile skin, such as skin tears and shin lacerations, but they are not particularly useful in and around mucous membranes because they often fall off prematurely. They also are not very useful for wounds on the hands and feet or wounds directly over bending areas. Extreme care should be used in lacerations around the eyes in order to prevent runoff and matting of the eyelashes. If adhesive does get into the patient’s eye, use ophthalmic ointment to hasten sloughing of the adhesive.
The table above provides a comparison of the various wound closure devices.
Reality Check: Sutures are not the only reliable means of wound closure. Effective alternatives exist, depending on wound type and location.
MYTH #8
DOUBLE-LAYER SUTURING YIELDS BETTER COSMESIS FOR FACIAL WOUNDS THAN SINGLE-LAYER SUTURING
Emergency physicians rarely use deep sutures, but plastic surgeons frequently use them in the face. Scar width is related to wound tension and correlated with the force required to close the wound. Deep sutures have been shown to increase infection rates in contaminated animal wound models. Is there any proof that deep sutures decrease infection and scar formation in facial lacerations?
A study was conducted on 17 patients undergoing laminectomy who had the upper and lower parts of their incisions closed randomly either with or without 4/0 subcuticular polyglycolic acid sutures in addition to percutaneous nylon sutures. The conclusion? The width of the scar was unaffected by the presence of subcuticular sutures.
Another trial looked at time to closure and cosmesis in 60 patients with nongaping (less than 10 mm wide) facial lacerations randomized to a single layer of uninterrupted 6/0 polypropylene sutures or a double layer of deep dermal buried 5/0 polyglactin sutures, plus simple interrupted 5/0 polypropylene sutures. The authors concluded that there was no benefit in terms of scar width and cosmetic appearance in using deep sutures in addition to the superficial single layer of percutaneous interrupted sutures. In fact, there was an expected time advantage (six minutes) in using only a single layer of sutures.
Reality Check: In nongaping facial lacerations, there is no benefit in using double-layer instead of single-layer suturing. Deep dermal sutures may still be required in high-tension gaping facial lacerations.
FROM PLANTS TO ANTS: A BRIEF HISTORY OF WOUND CLOSURE
Wound closure has an interesting and occasionally bizarre history. The first written records of wound treatment date from around 2500 B.C. Plants figured prominently in wound treatment for more than 1000 years. Herbs were applied in a balsam, and leaves and grasses were used as bandages. Honey, butter, clay, and bark were used as medicines, and urine, dung, and blood were used more for ritualistic purposes. During the Middle Ages, purulence was considered essential for wound healing and wounds were intentionally contaminated to produce pus. The earliest record of using sutures to close wounds comes from a mummy dating from 1100 B.C. Although staples for closing wounds were not developed until the early 20th century, a form of this technique was used in the ancient Hindu civilization, where wounds were closed with the jaws of dead ants. |
MYTH #9
EPINEPHRINE FOR DIGITAL BLOCK MAY CAUSE GANGRENE
Since 1888, there have been 48 cases of digital gangrene after the administration of an anesthetic. Epinephrine was used in 21 of these cases, but its concentration was unknown, and in many cases tourniquets were used, making data interpretation difficult. In contrast, no cases of digital gangrene have been reported since 1948, when a commercial combination of epinephrine in lidocaine was introduced.
A 1991 study randomized patients undergoing hand surgery to digital blocks with lidocaine with or without epinephrine and found no cases of gangrene. Furthermore, the addition of epinephrine reduced the need for additional injections of an anesthetic and tourniquet use, which are far more detrimental to digital blood flow than epinephrine. In addition, an ultrasonic study of digital blood flow found that an injection of epinephrine resulted in a transient decrease in blood flow that completely resolved within 60 to 90 minutes. Finally, a recent observational report of more than 5000 patients undergoing digital block with lidocaine and epinephrine failed to demonstrate any cases of digital gangrene or other complications.
Reality Check: No evidence links epinephrine use with digital gangrene. While epinephrine may have a vasoconstrictive effect, that effect may actually be desirable and resolves in 60 to 90 minutes.
BEYOND THE MYTHS
Millions of patients visit emergency departments every year for the treatment of wounds. Because wounds are so common, misconceptions flourish about how to care for them. Old habits also die hard. As emergency physicians, we must keep our minds open and look beyond the myths to the evidence supporting different treatments. As always, we must also use good clinical judgment and common sense when determining how best to manage patients with wounds.
Suggested Reading
Berk WA, et al.: Evaluation of the “golden period” for wound repair: 204 cases from a third world emergency department. Ann Emerg Med 17(5):496, 1988.
Chen E, et al.: Primary closure of mammalian bites. Acad Emerg Med 7(2):157, 2000.
Hinman CD and Maibach H: Effect of air exposure and occlusion on experimental human skin wounds. Nature 200:377, 1963.
Hollander JE and Singer AJ: Laceration management. Ann Emerg Med 34(3):356, 1999.
Hollander JE, et al.: Irrigation in facial and scalp lacerations: does it alter outcome? Ann Emerg Med 31(1):73, 1998.
Hutchinson JJ. Prevalence of wound infection under occlusive dressings: a collective survey of reported research. Wounds 1:123, 1989.
Krunic AL, et al.: Digital anesthesia with epinephrine: an old myth revisited. J Am Acad Dermatol 51(5):755, 2004.
Medeiros I and Saconato H: Antibiotic prophylaxis for mammalian bites. Cochrane Database Syst Rev (2):CD001738, 2001.
Moscati RM, et al.: A multicenter comparison of tap water versus sterile saline for wound irrigation. Acad Emerg Med 14(5):404, 2007.
Perelman VS, et al.: Sterile versus nonsterile gloves for repair of uncomplicated lacerations in the emergency department: a randomized controlled trial. Ann Emerg Med 43(3):362, 2004.
Singer AJ, et al.: Closure of lacerations and incisions with octylcyanoacrylate: a multicenter randomized clinical trial. Surgery 131(3):270, 2002.
Singer AJ, et al.: Evaluation and management of traumatic lacerations. N Engl J Med 337(16):1142, 1997.
Singer AJ, et al.: National trends in ED lacerations between 1992 and 2002. Am J Emerg Med 24(2):183, 2006.
Singer AJ, et al.: Single-layer versus double-layer closure of facial lacerations: a randomized controlled trial. Plast Reconstr Surg 116(2):363, 2005. |
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