have proved themselves to be the ideal dressing for medium to high exuding wounds
over the past thirty years; the literature demonstrates their value as a gentle,
almost pain free primary dressing for a range of indications from donor sites
to cavity wounds.
Alginate dressings, originally derived
from seaweed, have been used for many years for a variety of wounds. The substance
was used as a haemostatic agent (Gilchrist and Martin 1983), particularly in dentistry,
but no companies now hold product licenses for haemostasis.
Like many long
established products, there are comparatively few large, well-randomized studies
(Thomas 2000a,b,c). In recent years, while alginates have been used as controls
for studies of newer materials, few researchers have explored the properties of
Alginate dressings consist of naturally occurring
polysaccharides that are derived from the cell walls of brown seaweed. They are
manufactured as non-woven, fibrous sheets or rope-like packing. The dressings
have been shown to be ideal for moderate to heavily exudating wounds (Limova 2003),
though they do require a secondary dressing; such as a film if the wound is relatively
dry, or an absorbent pad if there is heavy exudate.
In an exuding wound
bed, alginate dressing fibres form part of the gel and do not have to be manually
removed, provided the dressings are used, as recommended, for moderate to heavily
exudating wounds (Limova 2003). This avoids the need to disturb granulating tissue,
and makes the task of dressing removal easier for both professional and patient.
(Gilchrist and Martin 1983). The dressings are manufactured to be easily prepared
for the wound, either by cutting the square product or moulding the rope
Few studies have compared different alginate dressings; one
reported no significant differences in their effect on epithelialisation, but
did identify handling differences, in a pig study of four brands (Agren 1996).
A more recent study compared two brands, used for the treatment of leg ulcers,
and also found minor differences (such as wound odour), but no significant differences
in healing performance (Limova 2003).
Few studies have investigated the
secondary dressings most appropriate for alginates. In all but those with very
high exudate, it would seem logical to use an occlusive dressing, for infection
control reasons, as with any exuding wound (Lawrence 1994), and there several
factors to consider in the selection, such as convenience and ease of use for
the professional; comfort and pain on removal for the patient; cost. In one small
study, Beldon (2004) compared dressings on the basis of which provided the greatest
comfort, had the fastest healing time and could be removed without trauma, and
found that alginate with film cover was the superior choice with the added
benefit of being able to assess the need for dressing change without interfering
with the existing dressing. However, there is little information on the ideal
secondary dressing, so selection will depend on first principles.
are one of the dressings of choice for any moderate to highly exuding wounds,
and studies have demonstrated their value in a variety of wound types:
Split skin graft donor sites
Alginates made their first big impression
in wound care in the 1980s, as dressings for split skin graft donor sites; they
rapidly showed that they were superior to paraffin gauze, the usual dressing for
donor sites at that time. A study comparing the two dressings had to be abandoned
by Attwood (1989), as there was consistently better healing under the alginates.
These findings have been confirmed more recently by O'Donoghue et al (1997).
recent studies suggest that newer materials, such as polyurethane foam dressings,
may also have a role with these wounds; so far, however, there is not enough clinical
evidence to conclude that such dressings should replace alginates (Vaingankar
2001), but there is a wider choice of dressings available.
Groves and Lawrence
(1986) reported on the ability of alginate dressings to reduce blood loss from
skin graft donor sites, with significant haemostasis being achieved in the immediate
post operative period.
Dressing removal is also an issue with split skin
graft donor sites; a study that compared calcium alginate and a silicone-coated
polyamide net dressing found no significant difference in the pain associated
with dressing changes. However, in the net dressing arm of the trial, absorbent
gauze adhered to the donor site through the fenestrations in the dressing, and
a layer of paraffin gauze had to be inserted between the experimental dressing
and the cotton gauze, after the painful experiences of the first two patients
(O'Donoghue et al 2000).
The dressing removal benefits
found in donor site management may also apply in the management of burns too.
Surgery can increase complications, both by increasing local bleeding, and adding
the risk of skin grafts being removed with the dressing. Kneafsey et al (1996)
report that the control of minor haemorrhage during excision and grafting following
deep burns to the hand is difficult; while postoperative haematoma can reduce
graft take. Using alginates during and after the operation was found to be of
immense help in minimizing these problems.
3. Cavity Wounds
dressings are extremely absorbent, making them particularly useful for removal
of moderate to large amounts of exudate (Motta 1989); this can make the dressings
particularly useful for cavity wounds and infected surgical wounds.
trial comparing calcium alginate with the more traditional saline-soaked gauze
for packing abscess cavities, following incision and drainage, found that the
alginate packs were significantly easier to remove, with significantly less pain
than the traditional pack (Dawson et al 1992).
Despite the introduction
of newer, more absorbent dressings, alginate rope is still widely used in packing
cavities. Sadly, the limited research in this area does not include any definitive
comparisons between alginates and other materials; there is a need for such research
to consider fluid handling properties, as well as ease of use and patient comfort
on dressing application and removal.
There is little doubt that vacuum dressings
are having a major impact on cavity wounds (Smith 2004), but there is still a
need for research on cost-effectiveness, particularly with smaller cavity wounds,
in order to reassess the role of more traditional dressings.
High grade pressure ulcers often exude considerable amounts of fluid;
one study set out to compare a sequential strategy - calcium alginate for four
weeks, followed by hydrocolloid dressings - with treatment by hydrocolloids alone.
Significantly faster healing was found in the sequential treatment group than
in the control group (Belmin et al 2002).
When the efficacy of an alginate
dressing was compared to that of an established protocol (using dextranomer paste
in full-thickness pressure ulcers), a highly significant advantage was found in
favour of the alginate; median time taken to achieve this healing was four weeks
with alginate and more than eight weeks in the control group (Sayag et al 1996).
Diabetic foot lesions
Another study aimed at comparing both the efficacy
and tolerance of an alginate wound dressing, with a paraffin gauze dressing, in
the treatment of diabetic foot lesions, and found the alginate to be significantly
better, in terms of healing (p=0.04), frequency of re-dressing (p=0.07), and in
the pain associated with dressing changes (p=0.047) (Lalau et al 2002).
Alginates may have a role in heavily exuding leg ulcers, but
there is a dearth of helpful clinical studies. A key issue is the selection of
appropriate secondary dressings, and this issue is highlighted by Schultzes
study (2001), which compared an alginate plus secondary dressing with a polyurethane
foam dressing in managing leg ulcers. A longer wear time was observed in the polyurethane
dressing group compared with the alginate group (p = 0.001), but the study did
not find significant differences in healing, and did not investigate alternative
Advantages of Alginates
Motta (1989) argued
that alginate dressings were cost-effective because the frequency of dressing
change was significantly reduced (compared to contemporary dressings).
dressings, used in moderate to heavily exuding wounds, maintain a moist environment
at the wound, that promotes healing and the formation of granulation tissue, and
as the dressing can be rinsed away with saline irrigation, removal of the dressing
does not interfere with healing granulation either, a factor that makes dressing
changes virtually painless (Motta 1989).
This major benefit has been tested
and confirmed against several other dressings, even where no other clinical advantage
is demonstrated (Bettinger et al 1995), and in a variety of different wound types,
where the pain associated with dressing removal is a major issue, including haemorrhoidectomy
(Ingram et al 1998).
Calcium alginates are effective haemostats in wound
dressings (Steenfos and Agren 1998), acting as calcium ion donors with a potentiating
effect on coagulation and platelet activation. The benefit does vary between products,
with alginates containing zinc ions having a greater effect (Segal et al 1998).
Neither of these studies considered arterial bleeding, in which alginates are
In comparisons with paraffin gauze, the quality of healing
has been found to be significantly better when alginate dressings have been used
(Attwood 1989, Basse et al 1992)
Limitations of Alginates
and Varley (1987) found that cellular reactions could be provoked in full thickness
wound models without occlusion, where there was an insufficient volume of wound
exudate to completely wet the alginate fibres. Similar findings have been reported
in animal studies (Suzuki et al 1998), but clinical reports involving human subjects
have proved impossible to find.
These experimental studies might have been
rather different if the authors had used occlusion appropriately, and assessed
each wound for its suitability for the dressing; alginates are best avoided unless
there is sufficient exudate to form a gel which would almost entirely remove the
risk of alginate fibres remaining in the wound bed.
in vitro study found that a hydrofibre dressing sequesters and retains micro-organisms
upon exposure to simulated wound fluid significantly more effectively than an
alginate (p < 0.05), and may help in reducing the microbial load in wounds.
The clinical significance of this remains to be confirmed (Bowler 1999).
et al (1994) reported a florid foreign body giant cell reaction elicited by an
alginate used as a haemostat in a dental cavity, and not removed afterward. This
further emphasizes the need to confine alginates to wounds where there is sufficient
moisture to form a gel that can easily be flushed away with saline solution; and
to remove excess alginate material from dry areas.
Bhalla et al (2002) reported
a calcium alginate pack left in place to control bleeding following excision of
the left submandibular gland. After an extended period of time, the pack excited
a foreign body reaction, which appeared to be a recurrence of the tumour on, when
seen on a computed tomogram.
Pricing Authority (2007) lists four varieties of alginate dressings:
Alginate dressing - For medium to heavily exuding wounds.
are not ideal for infected wounds, and should not be used on dry wounds, or those
covered with dry necrotic tissue. They are manufactured in a variety of sizes,
from 5cm x 5cm to 30cm x 61cm these dressings are designed to lay flat
on the wound bed, and should be trimmed to fit inside the area where exudate appears.
If required, a double layer may be used, but in all cases a retention dressing
is required, and an absorbent pad is an option. If the dressing is to remain in
place days, then the user must decide if an occlusive dressing is required to
maintain the moisture required for best effect and easy removal, or whether absorbent
materials will be required to avoid strikethrough and leakage.
brands are ActivHeal, Algisite M, Algivon, Algosteril, Curasorb, Curasorb Plus,
Curasorb Zn, Kaltostat, Melgisorb, Sorbalgon, Sorbsan, Suprasorb A, Tegagen, and
2. Alginate Dressing with Absorbent Backing - For medium to heavily
With similar uses as the standard dressing, absorbent
padding is provided for ease of application. Sizes range from 7.5cm x 10cm to
19cm x 24cm (with a 15cm x 20cm contact area).
Current UK brands are Sorbsan
Plus and Sorbsan Plus SA (with adhesive border).
3. Alginate Containing
Hydrocolloid Dressing - For medium to heavily exuding wounds.
from 5cm x 5cm to 10cm x 20cm.
Current UK brands are SeaSorb Soft, Urgosorb
4. Capillary Action Absorbent Dressing
For low to heavily exuding
wounds; these are not appropriate for very vascular wounds (e.g. fungating wounds),
or where there is a risk of arterial bleeding (research showing haemostatic properties
has focussed on .
Current UK brands are Acticoat Absorbent, ActivHeal, Algisite
M-Rope, Algosteril Rope, Curasorb Rope, Curasorb Zn Rope, Curasorb Zn Rope, Kaltostat,
Melgisorb Cavity, SeaSorb Soft Filler, Sorbalgon T, Sorbsan Packing, Sorbsan Ribbon,
Suprasorb A, Tegagen, Trionic Rope, Urgosorb Rope,
The future of Alginates
dressings have been shown to be useful as carriers of therapeutic agents. As early
as 1993, a comparison of dry alginate dressing, saline moistened alginate dressing
and bupivacaine hydrochloride (0.5%) moistened alginate dressing in post-operative
split skin graft donor sites, showed a significant reduction (p < 0.04) in
post-operative pain in the bupivacaine-alginate group at 24 and 48 hours (Butler
et al 1993).
A number of recent pilot studies have investigated using alginates
to carry other active agents, but while these look promising, their value and
place in wound care have yet to be confirmed.
Van der Weyden (2005) reported
antibacterial, anti-inflammatory and deodorizing success, using a honey-impregnated
alginate dressing. This was a case history of a man with challenging venous ulcers.
value of silver as a topical anti-microbial agent is not in doubt, but the efficacy
of specific silver-bearing wound products is remains controversial (Hermans 2006).
Silver sulfadiazine-loaded alginate microspheres may be able to deliver
silver sulfadiazine in a controlled fashion, controlling infection for extended
time period with reduced dressing frequency, while enabling easier assessment
of the wound; laboratory studies are ongoing (Shanmugasundaram 2006). Silver-releasing
dressings for wounds at high risk of infection may influence prognosis; however,
the evaluation of these advantages is complex and methodology will need to be
refined before proper evaluation can take place (Meaume 2005).
With the huge number of new dressings made available in recent
years, it is inevitable that others dressings will equal the benefits offered
by alginates, and research increasingly uses alginate dressings as the control,
rather than the experimental dressing (Armstrong and Ruckley 1997, Schultze 2001,
Vaingankar 2001). Thus far, however, such trials suggest a need for further investigation
rather than substantiate a claim for all-round superiority.
the literature on alginate dressings, and found that, despite their widespread
use, alginates have featured in few properly controlled clinical studies (Thomas
2000a,b,c). He concluded that alginates do offer advantages over traditional dressings
for some clinical indications and highlighted the lack of understanding about
the importance of secondary dressing systems that must be used in with alginate
dressings; the choice of both the primary alginate dressing and the secondary
dressing can influence treatment outcomes.
It is a little sad to report,
several years later, that no one has accepted the challenge to investigate the
most appropriate secondary dressings. It would be useful to confirm that a vapour-permeable
film dressing is best for low-exudate wounds, as first principles suggest, and
still more useful to investigate the role of absorbent secondary dressings, in
the context of the ideal frequency of dressing changes, and the implications for
wound infection and infection control.
Many dressings with similar
indications to alginates have never been directly compared with them in properly
controlled trials. As most modern dressings are much more expensive than alginates,
even allowing for secondary dressings (Prescription Pricing Authority 2007), practitioners
really need such information to make the best, most cost effective, choices.
article is intended to remind clinical nurses of the potential usefulness of this
versatile dressing; it has been around too long to get the fanfares associated
with newer products, but it remains effective, and is almost unrivalled in its
ability to make dressing changes a more gentle experience for the patient.
the specialist, alginates remain a viable alternative to more complex and expensive
products, and still have a place in the tissue viability armoury. Now, more than
ever, practitioners need to examine all the options available for a particular
situation; if the wound requires a dressing that is easy to handle, largely pain-free
on removal, has haemostatic qualities and excellent fluid handling ability, then
alginates still have no rival. But in the many cases where only one or two of
these qualities are required, other dressings may be as good then it becomes
a matter of a cost effective solution. Few dressings can match alginates in a
value for money comparison; still fewer can offer the gentle touch.
have been deliberately excluded from this web publication, as - sadly - plagiarism
and other academic theft has become such a problem, and I do not wish to facilitate
that. However, The references can be made available for other needs. Please write
with your request - and the rationale for it. I apologise for any inconvenence;
but I know you understand.
Submitted: July 2007© Andrew Heenan