Skin glues for wound closure

Skin glues are a safe and effective method to close selected wounds.

They are also cost-effective and help prevent infection.

Ideally, wounds should be less than 4 cm, not contaminated or infected and have skin edges that are not under tension. Wounds should be closed within 12 hours.

Most patients will be children with short clean wounds.

Dehiscence is slightly higher with skin glues than with sutures, but the cosmetic outcome is comparable and skin glues are painless.

Closure of wounds is often needed to promote wound healing and to produce an acceptable cosmetic result. Traditionally sutures and also adhesive strips have been used. Skin glues are safe and effective but wound selection is important.^1-4

Skin glues are cyanoacrylates. Derivatives with long chains are less reactive and stronger. They are available in liquid monomer formulations which react with formaldehyde on contact with skin or other surfaces. This polymerisation produces an exothermic reaction to create a bridge while becoming adherent to the skin.

Today's products are all effective and non-toxic and produce strong bonds.⁵ One study has shown that the current adhesive properties have a bursting strength equivalent to 4/0 nylon in an intracuticular wound closure.²

Not all wounds are suitable for skin glues (Box 1) – it is likely that they are only appropriate for 15–20%.² In particular, bites should not be treated with glues. Wounds should be less than 12 hours old, clean and free of debris.

Most wounds studied, particularly in emergency departments, were 1–6 cm. Some experts believe that wounds greater than 4 cm should not be closed with skin glue alone⁶ while others believe up to 10 cm is acceptable ^7,8 . A general agreement is that for optimum results, wounds should be less than 4 cm in length. Longer wounds have increased rates of dehiscence.

Skin glues should be used only for superficial approximation of skin. With surgical incisions, wound closure of layers should be performed and ideally glue should only be used in the skin approximation. Similarly in all other wounds which are gaping, it is vital to have skin approximation before applying the skin glue.

Without deeper sutures to approximate the skin, using skin glues to close excision sites is associated with increased rates of dehiscence. ^2,9 Glues may be used over joints only when accompanied by deeper tension sutures and splinting. ^1,2 They are generally acceptable for the treatment of skin flaps.² Glues do not appear to compromise circulation further given that the circulation is often already compromised. Nail bed repair has been successfully reported.

Applying skin glue is painless. In about 20% of patients there is a report of a sensation of mild heat but no actual pain.¹ Wound infection rates are low (less than 3%) and are not increased with skin glues.⁵

Procedure time is reduced.^1,2,5,8 Studies reported that the time of the actual wound repair in all settings was less than formal suturing. Sedation, which is sometimes used in children having sutures, is not needed with skin glues.

Cosmetic appearance with skin glues is comparable to outcomes with sutures and strip approximation.¹ Most of the trials have used a blinding method with photographs assessed by plastic surgeons, other doctors and patients themselves. Comparisons were made of appearance, absence of step-off, margin irregularities, separation, edge inversion and wound distortion. The results universally recorded that final cosmetic appearance for skin glues was similar to sutures, and both were better than adhesive strips. ^8,9

Skin glues are expensive. However, when compared with equipment and labour costs as well as the need for follow-up for suture removal, the overall cost is felt to be equivalent to sutures.¹¹

Patient satisfaction with skin glues was higher than with sutures in most studies. Reasons included lack of pain, ease of wound care and no need for follow-up and suture removal.

There is no chance of needle-stick injury with skin glues. They provide a barrier for short-term exposure to water. Swimming is generally not recommended.

In studies, 4% of wounds reopen with skin glues compared to 1–2% with sutures. This was thought to be due to a combination of poor technique, poor wound selection, but most importantly breakage of bonds or sloughing from the skin surface. ^1,2 Dihescence may cause delayed healing, poor cosmetic result and possible infection.

Patients may not feel that glue alone is adequate.⁷ This was found generally in active males who felt there was a higher chance of wound breakdown. Some patients are allergic to the cyanoacrylate or residual formaldehyde.

Accurately applying skin glues is easy (Box 2) and takes less than an hour to learn. In contrast, optimising suture usage takes about two years.¹² The wound still needs to be irrigated and prepared before applying skin glues.

Antibiotic ointments should not be used in conjunction with the application of skin glues. Care should be taken not to get the glue near or in the eye. Eyes should be protected with gauze to prevent eyelid attachment or corneal deposition. Antibiotic ointment or petroleum jelly can facilitate removal of glue if corrections are required.

Applying the glue

The two most common applicators for skin glues involve pressure on the container with gravity assisting. They are difficult to apply upwards on a wound. In one type (Fig. 1A), the inner glass container is crushed between the fingers which starts the polymerisation process. The liquid flows easily from the bottom of the container by gravity and pressure feed to an outward nozzle which allows continuous application due to lower viscosity. The other type (Fig. 1B) requires scissors to open the feeder and has larger droplets with higher viscosity to allow droplet application. The nozzle is then used to spread the coating.

The skin edges are approximated with fingers of the other hand, taking care not to include the gloves in the application process. It is important to practise controlling the applicator and get used to adhesive viscosity. The glue should cover the wound plus about 5–10 mm of skin on either side. Polymerisation takes 30–45 seconds. Two additional layers should be used, with 10–15 seconds between each layer. Full strength is achieved after 2.5 minutes.

Careful wound selection and practice of the technique make wound closure with skin glue acceptable in up to 20% of wounds. An increased rate of wound dehiscence is a potential drawback.

Conflict of interest: none declared

Singer AJ, Kinariwala M, Lirov R, Thode HC Jr. Patterns of use of topical skin adhesives in the emergency department. Acad Emerg Med 2010;17:670-2.