Alginates are a 'natural' form of dressing manufactured from different types of algae and seaweed, which form into a gel when they come into contact with liquid. They are designed to absorb wound fluid (exudate) and, therefore, control the wound's moisture levels. Alginates can also be used to stop bleeding (Kaneda et al, 2008).
How do alginate dressings work?
Alginate dressings are dry until they come into contact with the wound, whereupon they 'up-take' fluid into the space between their fibres, and into the fibres themselves. This can help to absorb significant amounts of exudate. Once they have formed into a gel, alginates can also aid healing through promoting the growth of fresh epidermis (upper layer of skin) (Timmons, 2009). The gel that is formed by an alginate dressing helps to stop the wound from drying out and aids debridement.
Note: Not all alginates are the same: the amount of fluid absorbed varies from product to product.
There are many alginate products available, how do I select the right one?
Each patient has different requirements 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?
Normally, the volume of exudate produced by a wound will reduce over time as the wound heals. A certain amount of exudate is healthy, as it aids moist wound healing by promoting growth factors as well as proteins (metalloproteinases) and cells (macrophages), which help healing (Cutting, 2003). A 'healthy' amount of exudate also prevents a wound from drying out (World Union of Wound Healing Societies [WUWHS], 2007). However, if a wound becomes chronic (where healing is delayed), volumes of exudate can increase which should alert the clinician to problems such as infection or inflammation (Ratliff, 2009). As alginates are designed to absorb fluid they can help to manage excess exudate. There are also superabsorbent types of alginate dressings available (Clark, 2012).
What kind of wounds can an alginate dressing be used on?
Alginate dressings have traditionally been used on 'wet' wounds, which are producing exudate, and 'sloughy' wounds (where there is significant dead tissue), including:
- Moderately or heavily exuding wounds
- Full-thickness burns
- Surgical wounds
- Donor sites
- Chronic ulcers
- Superficial or cavity wounds.
Does the wound need to be debrided?
Alginate dressings can aid autolytic debridement, as they maintain a moist wound environment where debridement is promoted through the body's own enzymes (Gibbs, 2010).
Is the wound bleeding?
When an alginate dressing comes into contact with a wound, calcium ions are released into the wound. Calcium is a natural element in coagulation, which means that alginates can help to regulate blood flow in a wound (Timmons, 2009).
When should an alginate not be used?
Alginates should be used with caution in dry or lowly exuding wounds as they can adhere to the wound bed. The following are also contraindicated for alginate dressings (Clark, 2011):
- Wounds with little exudate
- Surgical implantations
- Patients with allergies to alginate components
- Third-degree burns.
Is the wound in an awkward or difficult-to-dress area?
Alginates are ideal for treating deep, cavity wounds, as the gel they form is conformable, meaning that it will fit with the shape of the wound (Timmons, 2009). Alginates also come in a variety of presentations, such as ribbon or flat non-woven pads. Many alginate dressings require a secondary dressing to keep them in place, although self-adhesive dressings are available (Clark, 2012).
Is the dressing going to be used under compression?
Applying compression can be a problem for wounds that produce high volumes of exudate, however, some alginates are produced as flat sheets with an added absorbent layer and can be used on leg ulcers as well as under compression (Timmons, 2009). It is important to check the manufacturer's instructions to make sure that the dressing is suitable for use with compression.
Does the patient have fragile skin?
Similar to other dressings designed to absorb exudate, leakage of fluid onto the surrounding skin can possibly cause maceration. A protective barrier film can be applied to help prevent this (Clark, 2012).
Is antimicrobial action needed?
Many alginate dressings are combined with an antimicrobial agent to combat infection. Some contain silver and there are also reports of antimicrobial action with honey-impregnated alginate dressings (Van der Wyden, 2005). It is important to change an alginate frequently if infection is suspected, as any microbes that have been absorbed into the dressing are then removed (Clark, 2012).
Tips for application and removal
It is important to irrigate the wound after the use of an alginate dressing in order to fully clean out any fibres. Dressings should be changed when there is 'strikethrough' of exudate to the secondary dressing (Clark, 2012). If there is any sign of adherence to the wound bed, alginates can be moistened before removal.
Although cost-effectiveness is important, choosing the cheapest absorbent dressing is not necessarily the best thing to do, as 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 nursing-patient relationship and is in line with national policy.
- Fluid-handling capacity
- Secondary dressing required
- Can be used under compression
Clark M (2012) Technology update: rediscovering alginate dressings. Wounds International. Available online.
Cutting K (2003) Wound exudate: composition and functions. Br J Comm Nurs 8(9): 4–9
Gibbs K (2010) Absorptive dressings: alginates and Hydrofibers. Adv Wound Care 1: 142–7
Kaneda K, Kuroda S, Goto N, Sato D, Ohya K, Kasugai S (2008) Is sodium alginate an alternative haemostatic material in the tooth extraction socket. J Oral Tiss Eng 5(3): 127–33
Ratliff CR (2008) Wound exudate: an influential factor in healing. Adv Nurs Practice 16(7): 32–5
Timmons J (2009) Alginates as haemostatic agents: worth revisiting? Wounds UK 5(4): 122–5
Van der Weyden EA (2005) Treatment of a venous leg ulcer with a honey alginate dressing. Br J Community Nurs Suppl:S21, S24: S26–7
World Union of Wound Healing Societies (2007) Wound Exudate and the Role of Dressings: a consensus document. Wounds International. Available online.