Polyhexamethylene biguanide (PHMB) dressings
Polyhexamethylene biguanide hydrochloride (PHMB) has been used for over 60 years as an antimicrobial agent. Commercially, it has been used as a general disinfectant to treat swimming pools (McDonnell and Russell, 1999; Moore and Gray, 2007), contact lenses (Moore and Gray, 2007) and in the food industry due to its broad spectrum of antimicrobial activity. Today, PHMB dressings are used as an alternative to other antimicrobial dressings on the market. Laboratory studies have demonstrated cell death when Escherichia coli were in contact with PHMB (McDonnell and Russell, 1999), and prevention of degradation of wound fluid and skin proteins with Pseudomonas aeruginosa induced infection (Werthen et al, 2004).
How does PHMB work?
- PHMB works by binding to the bacterial cell membrane, causing complex reactions to alter the integrity of the wall. This allows entry of the PHMB, reducing wall strength and hence, death of the bacterium (Gilbert, 2006; Hubner and Kramer, 2010; McDonnell and Russell, 1999)
- PHMB impregnated dressings may also help reduce pathogenic contamination of the underlying wound (Main, 2008).
Note: Not all PHMB products are the same and the manufacturers’ instructions should be considered when treating the various types of wound.
There are many PHMB and PHMB combination products available, how do I select the right one?
Each patient has different needs that need to be considered when choosing the correct product. The following questions can help with dressing selection.
How much exudate is the wound producing?
If the wound is producing medium to high volumes of exudate, a plus or superabsorbent product may be required. However, if exudate production is low, a light or thin dressing may be more suitable. Correct exudate assessment (based on colour and amount) and management are essential both to maintain a moist wound healing environment and to prevent the periwound skin from maceration.
Methods for assessing exudate have been suggested by Falanga (2000), Bates-Jensen wound assessment tool (Bates-Jensen, 2007) and a proposed national wound assessment form (Fletcher, 2010). The latter uses the term ‘wound moisture level’ rather than exudate, and is based on the World Union of Wound Healing Societies (WUWHS) document on exudate (WUWHS, 2007). Clinicians should also refer to their local policy on exudate assessment.
How fragile is the patient’s skin: adherent or non-adherent?
Non-adherent PHMB dressings do not stick to the skin, so need to be secured in place with tape or light retention bandages. These dressings are suitable for use on fragile or damaged skin, where adhesive dressings may result in skin damage.
Adherent PHMB dressings have an adhesive backing so that they stick directly to the skin without needing to be held in place by other products.
Is the dressing going to be used under compression?
Most PHMB dressing can hold fluid; however, some cannot hold fluid under pressure. This means that if pressure is applied, such as by compression bandaging or body weight if the dressing is placed on the sacrum or heel, the fluid in the dressing may leak out. In such circumstances, dressings which have the ability to wick and lock fluid away should be used.
Some PHMB dressings have a film-backing which prevents strike-through; this can prevent bandages or other dressings which are being used to fix them in place from becoming wet.
Is antimicrobial action needed?
Most PHMB dressings have antimicrobial components, which help the dressings to kill the microorganisms that may be responsible for local wound infection or delayed healing. Antimicrobial dressings should only be used if infection is present, or if the patient is considered to be at an increased risk of wound infection.
Does the wound need protection?
PHMB foam dressings can also be used to protect and cushion ulcers, burns, surgically induced body exit, entry sites such as those made by intravenous (IV) catheters, J-tubes, G-tubes, venous central lines and chest drains. Manufacturers’ instructions should always be followed.
Where is the wound? Is it in a place that is difficult to dress?
Some wound sites such as the sacrum or heel can be difficult to dress. The range of PHMB and PHMB combination dressings are specifically designed for use in such anatomical areas.
Selecting a PHMB dressing
Selection of a PHMB dressing should be guided by:
- Volume of exudate
- Condition of skin
- Location of wound
- Use under compression
- Presence of infection.
Although cost-effectiveness is important, choosing the cheapest PHMB dressing is not necessarily the best thing to do; dressing choice should always be guided by the patient’s needs. If a dressing fails to perform well, more frequent dressing changes will be needed, incurring greater nursing time.
Patient choice and preference should always be considered. This helps to build up a good nurse–patient relationship, and is in line with national policy.
Wound care specialists should ensure that the patient is not sensitive to any additives or agents in the PHBM dressing and should ask about PHMB sensitivity before application. Moreover, as there are a variety of PHMB products on the market, contraindications and cautions should always be considered.
- Fluid-handling capacity
- Film backing/no film backing
- Secondary dressing required
- Can be used under compression
Bates-Jensen B (1997) The pressure sore status tool a few thousand assessments later. Adv Wound Care 10(5): 65–73
Falanga V (2000) Classifications for wound bed preparation and stimulation of chronic wounds. Wound Rep Regen 8(5): 347–52
Fletcher J (2010) Development of a new wound assessment form. Wounds UK 6(1): 92–9
Gilbert P (2006) Avoiding the resistance pitfall in infection control — does the use of antiseptic products contribute to the spread of antibiotic resistance? Ostomy Wound Management 52: 10A(suppl): 1S–3S
Hubner NO, Kramer A (2010) Review on the efficacy, safety and clinical applications of polihexanide, a modern wound antiseptic. Skin Pharmacol Physiol 23(suppl 1): 17–27
Main RC (2008) Should chlorohexidine gluconate be used in wound cleansing? J Wound Care 17 (3): 112–14
McDonnell G, Russell AD (1999) Antiseptics and disinfectants: activity, action and resistance. Clin Microbiol Rev 12 (1): 147–79
Moore K, Gray D (2007) Using PHMB antimicrobial to prevent wound infection. Wounds UK 3(2): 96–102
Werthern M, Davoudi M, Sonesson A, et al (2004) Pseudomonas aeruginosa-induced infection and degradation of human wound fluid and skin proteins ex vivo are eradicated by a synthetic cationic polymer. J Antimicrob Chemother 54(4): 772–9
World Union of Wound Healing Societies (2007) Principles of Best Practice: Wound Exudate and the Role of Dressings. A Consensus Document. Available online.