David M. Cline
Wounds can be closed primarily in the emergency department (ED) by the placement of sutures, surgical staples, skin-closure tapes, and adhesives.
All wounds heal with some scarring; however, preferred closure techniques make scars less noticeable.
In closing a laceration, it is important to match each layer of a wound edge to its counterpart. Care must be taken to avoid having one wound edge rolled inward.
The rolled-in edge occludes the capillaries, promoting wound infection. The dermal side will not heal to the rolled epidermal side, causing wound dehiscence when the sutures are removed, resulting in an inferior scar appearance.
The techniques described are an overview of basic wound closure, which should aid the practitioner in achieving acceptable results.
SUTURES
Sutures are the strongest of all wound closure devices and allow the most accurate approximation of wound edges.
Sutures are divided into two general classes: nonab-sorbable, and absorbable sutures, which lose all their tensile strength within 60 days.
Monofilament synthetic sutures such as nylon or polypropylene have the lowest rates of infection and are the most commonly used suture materials in the ED.
Synthetic monofilament absorbable sutures (eg, Monocryl®) are preferred for closure of deep structures such as the dermis or fascia because of their strength and low tissue reactivity.
Rapidly absorbing sutures (eg, Vicryl Rapide®) can be used to close the superficial skin layers or mucous membranes, especially when the avoidance of removal is desired.
Sutures are sized according to their diameter. For general ED use, 6–0 suture is the smallest, and it is used for percutaneous closure on the face and other cosmetically important areas.
Suture sizes 5–0 and 4–0 are progressively larger; 5–0 is commonly used for closure of hand and finger lacerations, and 4–0 is used to close lacerations on the trunk and proximal extremities.
Very thick skin, such as that of the scalp and sole, may require closure with 3–0 sutures.
SUTURING TECHNIQUES
Percutaneous sutures that pass through both the epidermal and dermal layers are the most common sutures used in the ED.
Dermal, or subcuticular, sutures reapproximate the divided edges of the dermis without penetrating the epidermis. These two sutures may be used together in a layered closure as wound complexity demands. Sutures can be applied in a continuous fashion (“running” sutures) or as interrupted sutures.
Improper tissue handling further traumatizes skin and results in an increased risk of infection and noticeable scarring. Gentle pressure with fine forceps is recommended.
SIMPLE INTERRUPTED PERCUTANEOUS SUTURES
Percutaneous sutures should be placed to achieve eversion of the wound edges. To accomplish this, the needle should enter the skin at a 90-degree angle. The needle point should also exit the opposite side at 90 degrees. The depth of the suture should be greater than the width. Sutures placed in this manner will encompass a portion of tissue that will evert when the knot is tied (Fig. 12-1).
An adequate number of interrupted sutures should be placed so that the wound edges are closed without gaping. Generally, the number of ties should correspond to the suture size (ie, 4 ties for 4–0 suture, 5 ties for 5–0 suture).
Straight, shallow lacerations can be closed with percutaneous sutures only, by sewing from one end toward the other and aligning edges with each individual suture bite. Deep, irregular wounds with uneven, misaligned, or gaping edges are more difficult to suture.
Certain management principles have been identified for these more difficult wounds.
Wounds with edges that cannot be brought together without excessive tension should have dermal sutures placed to partially close the gap.
When wound edges of different thickness are to be reunited, the needle should be passed through one side of the wound, and then drawn out before re-entry through the other side, to ensure that the needle is inserted at a comparable level.
Uneven edges can be aligned by first approximating the mid-portion of the wound with the initial suture. Subsequent sutures are then placed in the middle of each half until the wound edges are aligned and closed.
Simple interrupted sutures are the most versatile and effective for realigning irregular wound edges and stellate lacerations (Fig. 12-2). An advantage of interrupted sutures is that only the involved sutures need to be removed in the case of wound infection.
FIG. 12-1. Placement of simple interrupted sutures. The suture path should gather more tissue at its base than at its surface. Therefore, the suture will evert its skin edges when tightened.
FIG. 12-2. Stellate laceration closed with interrupted sutures.
CONTINUOUS (RUNNING) PERCUTANEOUS SUTURES
Continuous or running percutaneous sutures are best when repairing linear wounds. An advantage of the continuous suture is that it accommodates the developing edema of the wound edges during healing. However, a break in the suture may ruin the entire repair and may cause permanent marks if placed too tightly.
Continuous suture closure of a laceration can be accomplished by two different patterns. In the first pattern, the needle pathway is at a 90-degree angle to the wound edges and results in a visible suture that crosses the wound edges at a 45-degree angle (Fig. 12-3A).
In the other pattern, the needle pathway is at a 45-degree angle to the wound edges, so that the visible suture is at a 90-degree angle to the wound edges (Fig. 12-3B). In either case, the physician starts at the corner of the wound farthest away and sutures toward him- or herself.
DEEP DERMAL SUTURES
The major role of these sutures is to reduce tension. They are also used to close dead spaces.
However, their presence increases the risk of infection in contaminated wounds.
Sutures though adipose tissues do not hold tension, increase infection rates, and should be avoided.
With deep dermal sutures, the needle is inserted at the level of the mid-dermis on one side of the wound, and then exits more superficially below the dermal-epidermal junction (Fig. 12-4). The needle is then introduced below the dermal-epidermal junction on the opposite side of the wound and exits at the level of the mid-dermis. Thus, the knot becomes buried in the tissue when tying of the suture is completed.
The first suture is placed at the center of the laceration, while additional sutures then sequentially bisect the wound. The number of deep sutures should be minimized.
FIG. 12-3. A. Running suture crossing wound at 45 degrees. B. Running suture crossing wound at 90 degrees.
VERTICAL MATTRESS SUTURES
The vertical mattress suture (Fig. 12-5) is useful in areas of lax skin (eg, the elbow and the dorsum of the hand), where the wound edges tend to fold into the wound. It can act as an “all-in-one” suture, avoiding the need for a layered closure.
HORIZONTAL MATTRESS SUTURES
Horizontal mattress sutures are faster and better at eversion than vertical mattress sutures.
They are especially useful in areas of increased tension such as fascia, joints, and callus skin (Fig. 12-6). In order to avoid tissue strangulation, care must be taken not to tie the individual sutures too tightly.
FIG. 12-4. Placement of deep dermal suture. The needle is inserted at the depth of the dermis and directed upward, exiting beneath the dermal-epidermal junction. Then the needle is inserted across the wound and directed downward, exiting at the wound base. The suture knot is then placed deep in the wound.
DELAYED CLOSURE
Delayed primary closure is an option for wounds suspected of contamination, or for wounds presenting beyond 12 hours after injury.
With this method the wound is left open for a period of 3 to 5 days, after which it may be closed if no infection supervenes.
FIG. 12-5. Vertical mattress suture.
FIG. 12-6. Horizontal mattress suture.
STAPLES
Skin closure by metal staples is quick and economical, with the added advantage of low tissue reactivity.
Staples should be reserved for lacerations where the healing scar is not readily apparent (eg, scalp).
When placing staples, the wound edges should be held together with tissue forceps. Place the device gently against the skin and squeeze the trigger slowly. A properly placed staple should have its topside off the skin surface.
ADHESIVE TAPES
Adhesive tapes are the least reactive of all wound closure devices.
Skin-closure tapes are used as an alternative to sutures and staples and for additional support after suture and staple removal.
Tapes work best on flat, dry, immobile surfaces where the wound edges fit together without tension. Taped wounds are more resistant to infection than sutured wounds.
Tapes can be used for skin flaps, where sutures may compromise perfusion, and for lacerations with thin, friable skin that will not hold sutures.
Application of Benzoin to the skin surface 2 to 3 cm beyond the wound edges will enhance adherence. Maintain some space between individual tapes. The tapes will spontaneously detach as the underlying epithelium exfoliates.
CYANOACRYLATE TISSUE ADHESIVES
Cyanoacrylate tissue adhesives close wounds by forming an adhesive layer on top of intact epithelium.
Adhesives are most useful when they are used on wounds that close spontaneously, have clean or sharp edges, and are located on clean, immobile areas.
Do not apply adhesives within wounds, to mucous membranes, infected areas, joints, areas with dense hair (eg, scalp), or on wounds exposed to body fluids.
Wound closure with adhesives is faster and less painful than suturing and has comparable rates of infection, dehiscence, and cosmetic appearance.
Wounds with edges separated by more than 5 mm are unlikely to stay closed with tissue adhesives alone.
Subcutaneous sutures can be inserted to relieve this tension. Lacerations longer than 5 cm are unlikely to remain closed with tissue adhesives alone.
The adhesive is carefully expressed through the tip of the applicator and gently brushed over the wound surface in a continuous steady motion.
The adhesive should cover the entire wound in addition to an area covering 5 to 10 mm on either side of the wound edges.
After allowing the first layer of the adhesive to polymerize for 30 to 45 seconds, 2 to 3 additional layers of the adhesive are similarly brushed onto the surface of the wound, with pauses of 5 to 10 seconds between successive layers.
Take care to position the patient parallel to the floor, cover the eyes, and use gentle squeezing of the applicator to avoid problematic runoff.
Once applied, cyanoacrylate should not be covered with ointment, bandage, or dressing.
Instruct patient not to pick at edges of the adhesive. The area can be gently washed with plain water after 24 hours but should not be scrubbed, soaked, or exposed to moisture for any length of time.
The adhesive will spontaneously slough off in 5 to 10 days. Should a wound open, the patient should return immediately for closure.
For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 45, “Methods for Wound Closure,” by Adam J. Singer and Judd E. Hollander.