Cyanoacrylate Tissue Adhesives

This family of adhesives is extensively used in human and veterinary medicine. Cyanoacrylates comprise a series of alkyl cyanoacrylate monomers. These are liquids which polymerise in the presence of hydroxyl ions found in moist living tissues. The polymerised cyanoacrylate forms a strong bond, capable of providing comparable wound repair strength to sutures in appropriate circumstances. The adhesive also forms a protective layer which may help prevent wound contamination and infection.

Initially short-chain cyanoacrylates such as methyl and ethyl cyanoacrylate were developed, but were found to be very toxic to living tissues. Their toxicity is due to rapid tissue degradation releasing various toxins including formaldehyde. Subsequent development of longer-chain butyl and octyl compounds made medical use of these adhesives practicable. Longer-chain cyanoacrylates degrade more slowly, are less tissue toxic and are more flexible when polymerised.

The characteristics of butyl cyanoacrylates such as vetloc xcel offer an ideal compromise, giving good persistence of bond, flexibility and low tissue toxicity. Tissue adhesives can entirely replace sutures when closing low tension wounds, saving surgical time and simplifying post-operative care. They have been shown to be an effective means of closing surgical neutering wounds in cats, a procedure where time-saving and the elimination of patient-accessible sutures can both be valuable benefits.

Read our new paper

Tissue Adhesives: Simple Wound Closure

by Georgie Hollis BSc MVWHA Secretary, Veterinary Wound Healing Association

The safety of wound closure with tissue adhesives has long been established. Advantages include faster wound closure, fewer tissue reactions due to foreign material, less need for sedation and no need for removal. For some of us, changing from wound closure through suturing or staples to what may be perceived as more of a DIY method can seem like a leap of faith, but it is a method that is favourably supported in research. 

                                                                                                                                                                                                                                        Introduction

Recognition of the benefits of assisting closure by holding the opposing edges of wounds together has a past that reaches back as far as 5,000 years. Suture techniques were first documented fully in the 11th Century by the Moorish physician Abu al-Qasim al-Zahrawi. Often called the forefather of surgery, his texts extending to over 12 volumes feature techniques of internal and external wound closure using catgut derived from sheep or deer intestine. The principles and methods he described, although ancient, are still routinely used today.

Only 60 years ago did progress present in the form of the cyanoacrylate super glues. Born out of science and chemistry they at last offered the first potential substitute for routine suturing.

How tissue adhesives work

All tissue adhesives work similarly with the polymerisation (adhesion) process initiated in contact with hydroxide ions present in moisture, or proteins present on skin or other surfaces. The process of adhesion continues until the liquid monomer converts to a solid polymer in the presence moisture. Hardening of the compound begins, and due to the original liquid state a close contact with skin is achieved forming a secure, intimate adhesion.

When applied topically to apposed wound edges, tissue adhesives set rapidly forming a bridge across wound margins. Once set, the adhesive has a tensile strength equivalent to a healed wound at seven days and forms a water resistant barrier protecting the wound from contamination. A bacteriostatic effect is also a useful characteristic complimenting its role in wound closure. (Fig 1a: Use of VETLOC^® xcel without applicator, Fig 1b: VETLOC^® xcel used with applicator for a canine castrate).

In terms of performance, the butyl cyanoacrylates create the fastest adhesion, usually within 30 seconds of application. This is combined with a higher tensile strength than the octyl cyanoacrylates. Wounds closed with adhesives also avoid the need for secondary dressings due to the barrier effect. Furthermore, removal is not required as the adhesive sloughs away naturally with keratinized epithelium 5-10 days after application.

Click here to read the full paper or to download the PDF

Tissue adhesives from Vygon Vet:
Vetloc xcel
Application cannula

© Vygon (UK) Ltd 2009