Wound Adhesives, 2-Octyl Cyanoacrylate

  AUTHOR INFORMATION

Author: Nathan D Schwade, PhD, Research Director, Assistant Professor, Department of Otolaryngology-Head and Neck Surgery, University of Texas Southwestern Medical Center

Editor(s): Anthony P Sclafani, MD, Director, Associate Professor, Department of Otolaryngology, Division of Facial Plastic Surgery, New York Eye and Ear Infirmary, New York Medical College; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Dean Toriumi, MD, Associate Professor, Department of Otolaryngology, University of Illinois Medical Center; Christopher L Slack, MD, Consulting Staff, Otolaryngology-Facial Plastic Surgery, Lawnwood Regional Medical Center; and Arlen D Meyers, MD, MBA, Professor, Department of Otolaryngology-Head and Neck Surgery, University of Colorado Hospital


  INTRODUCTION

The cyanoacrylates first were synthesized in 1949 by Airdis. Coover et al described their adhesive properties and suggested their possible use for surgical adhesives. In the early 1960s, various surgical applications were investigated for these adhesives.

Cyanoacrylates can be synthesized by reacting formaldehyde with alkyl cyanoacetate to obtain a prepolymer that, by heating, is depolymerized into a liquid monomer. The monomer then can be modified by altering the alkoxycarbonyl (-COOR) group of the molecule to obtain compounds of different chain lengths. Upon application to living tissues (water or base), the monomer undergoes an exothermic hydroxylation reaction that results in polymerization of the adhesive. The shorter-chain derivatives tend to have a higher degree of tissue toxicity than the longer-chain derivatives.

Inflammation, tissue necrosis, granulation formation, and wound breakdown can occur when cyanoacrylates are implanted subcutaneously. The process causing the histologic toxicity is thought to be related to the by-products of degradation, cyanoacetate and formaldehyde. The local concentrations of these breakdown products are proportional to the rate of degradation (an aqueous degradation process) of the parent compound. Therefore, slower degradation rates result in less toxicity to the tissues. This is explained by the hypothetical possibility that slowly degrading compounds release degradation products more gradually, thereby permitting more effective clearance and invoking a less intense inflammatory response. The longer-chain compounds degrade much more slowly than the shorter-chain compounds, hence the lower reactivity of the longer-chain compounds.

Until recently, butyl-2-cyanoacrylate was the only commercially available cyanoacrylate tissue adhesive. Although butyl-2-cyanoacrylate is effective in closing superficial lacerations under low tension, it has several limitations. Several studies have shown wound-breaking strength in wounds repaired with butyl-2-cyanoacrylate to be equal to that in wounds repaired with sutures at 5-7 days; however, on day 1, breaking strength with the tissue adhesive is only approximately 10-15% of that in a wound sutured with 5-0 monofilament. After polymerizing, the adhesive becomes brittle and is subject to fracturing when used in skin creases or long incisions. This restricts the use of adhesives to areas of low tension, thus limiting their use for incision repair. Butyl-2-cyanoacrylate has been used widely with good cosmetic outcomes for various plastic surgical procedures (eg, upper lid blepharoplasty, facial skin closure, scalp wound closure).

The polymer 2-octyl cyanoacrylate was formulated to correct some of the deficiencies of the shorter-chain cyanoacrylate derivatives. As an 8-carbon alkyl derivative, this polymer should be less reactive than the shorter-chain derivatives. The slower degradation of the octyl derivatives may result in lower concentrations of the cyanoacrylate polymer by-products in surrounding tissues, resulting in less inflammation. Additionally, plasticizers are added to produce a more pliable and tissue-compatible product that flexes with the skin and remains inherent for longer periods of time. The 3-dimensional breaking strength of 2-octyl cyanoacrylate is 3 times that of butyl-2-cyanoacrylate and is closer to that of a 5-0 monofilament suture. This stronger flexible bond may allow its use on longer incisions.

The Food and Drug Administration (FDA) has approved 2-octyl cyanoacrylate for closure of incised skin. In addition to its surgical adhesive indication, 2-octyl cyanoacrylate (Dermabond) was approved by the FDA in January 2001 for use as a barrier against common bacterial microbes including certain staphylococci, pseudomonads, and Escherichia coli.

USE IN PATIENTS

Cost analysis has found that the use of tissue adhesives can significantly decrease health care costs and is preferred by patients. Adhesives also provide a needle-free method of wound closure, an important consideration because of blood-borne viruses (eg, HIV). The cyanoacrylates function as waterproof occlusive dressings, have antimicrobial properties against gram-positive organisms, and may decrease infections. They have been demonstrated to decrease histologic and clinical infection rates in contaminated wounds when compared to closure with sutures. If the adhesives are used improperly and are implanted into the wound, they can cause a foreign-body reaction and actually may increase infection rates.

The following discussion is limited to 2-octyl cyanoacrylate. Moreover, this text is designed to be only a guideline; as always, physicians should use their own discretion in the use of these materials. Although tissue adhesives have many advantages, their successful incorporation into the physician’s practice depends on understanding the indications, contraindications, and proper method of application. Without understanding these concepts, results are more likely to be unsatisfactory and advantages of adhesives are more likely to be lost.

The adhesive can be used topically to close skin incisions and lacerations alone, or it can be used in conjunction with deep sutures. Generally, the octyl products can be used in place of nonabsorbable sutures for primary closure of skin incisions and lacerations on the face. For facial incisions and lacerations that are under tension and when closing incisions and lacerations on the extremities and torso, deep (subcutaneous) sutures are recommended.

The adhesive should not be used on the oral mucosa, hands, feet, or joints, where repetitive movement and washing may cause the adhesives to slough prematurely. Other types of wounds that are not optimal for cyanoacrylates are decubitus ulcers, stellate lacerations, animal or human bites, and nonsurgical puncture wounds. The adhesive does not replace the requirement for good quality wound care. Wounds still need careful examination and exploration with irrigation and debridement when appropriate. These types of wound preparations still may require local anesthetic.

In learning to apply tissue adhesives, the most important concept is that they are for topical closure only. Give special care to ensure the adhesive will not leak between the wound edges. If used properly, the adhesive acts as a strong bridge to hold the well-opposed wound edges together. If placed in the wound, it acts as a barrier to proper epithelialization and may slow healing. Once in the wound, the adhesive also has the potential to cause a foreign-body reaction and to increase the incidence of infection.

Toriumi et al have published an excellent paper on the use of 2-octyl cyanoacrylate. They underscore two other important principles, which are the need to reduce skin tension at the site of the laceration and the need to ensure no dead space is present before sealing with the tissue adhesive.

Deep dermal sutures (vertical mattress stitches) are used to bring the skin edges into everted apposition. The everted edges are extremely important to successful closure with tissue adhesives, since they prevent scar broadening and improve the cosmetic result. The everted skin apposition should be maintained with forceps or fingers during the application of the 2-octyl cyanoacrylate. For best results, a thin layer should be applied over the epidermis and allowed to dry for approximately 20-30 seconds. This method prevents pooling and running of the tissue adhesive, and it also provides a layer of protection from the heat generated by the exothermic polymerization. Subsequent layers of cyanoacrylate then are applied over the top of this initial layer.

Several clinical studies have shown that 2-octyl cyanoacrylate provides cosmetic results equal to those of sutures. Therefore, given the speed and efficacy of this new tissue adhesive, it should firmly establish itself in the treatment repertoire for closure of the skin. Future investigations with this product no doubt will expand its use.
  BIBLIOGRAPHY

NOTE:
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Wound Adhesives, 2-Octyl Cyanoacrylate excerpt

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