Alginates have been used in various forms for fifty
years, and yet they remain a poorly understood and probably underused dressing.
Compared to many modern dressings, the literature is sparse and inconclusive.
This article aims to provide answers to many of the questions that users might
ask. It is not intended to be the final word; rather the opposite. These
answers are written to be a starting point and no more.
Originally these dressings were a loose
fleece formed primarily from fibres of calcium alginate. More recently they have
been developed so that the fibres have been entangled to form a product with more
cohesive structure, which increases the strength of the dressing when soaked with
exudate or blood. Some products also contain a significant amount of sodium alginate
to improve the gelling properties of the dressing. Other dressings have been produced
from freeze-dried alginate. 
Highly absorbent, biodegradable alginate dressings
are derived from seaweed. They have been successfully applied to cleanse a wide
variety of secreting lesions. The high absorption is achieved via strong hydrophilic
gel formation This limits wound secretions and minimizes bacterial contamination.
Alginate fibres trapped in a wound are readily biodegraded .
maintain a physiologically moist microenvironment that promotes healing and the
formation of granulation tissue. Alginates can be rinsed away with saline irrigation,
so removal of the dressing does not interfere with healing granulation tissue.
This makes dressing changes virtually painless. Alginate dressings are very useful
for moderate to heavily exudating wounds .
Reference 1: Thomas
S., Alginate dressings in surgery and wound management: Part 1. J Wound Care.
2000 Feb;9(2):56-60. 11933281
2: Gilchrist T, Martin AM., Wound treatment with Sorbsan - an alginate fibre
dressing; Biomaterials 1983 Oct;4(4):317-320 6640060
GJ., Calcium alginate topical wound dressings: a new dimension in the cost-effective
treatment for exudating dermal wounds and pressure sores; Ostomy Wound Manage
Once in contact with an exuding wound,
an ion-exchange reaction takes place between the calcium ions in the dressing
and sodium ions in serum or wound fluid. When a significant proportion of the
calcium ions on the fibre have been replaced by sodium, the fibre swells and partially
dissolves forming a gel-like mass.
The degree of swelling is determined principally
by the chemical composition of the alginate, which depends on its botanical source.
Although it is recognised that the differences between the various brands of dressings
may influence their handling characteristics - particularly when wet - it is generally
assumed that these differences are of limited relevance to the dressing's performance
clinically or at a cellular level.
There is some evidence to suggest, however,
that these assumptions may be wrong and that alginates may influence wound healing
in a number of ways not yet fully understood.
It has also become obvious that
there is a general lack of understanding about the importance of secondary dressing
systems that must be used in with alginate dressings. Careful examination of the
design and outcomes of the published studies suggests that the choice of both
the primary alginate dressing and the secondary dressing can play a major role
in determining treatment outcomes. [1,2,3]
Reference 1: Thomas
S., Alginate dressings in surgery and wound management: Part 1. J Wound Care.
Reference 2: Thomas
S., Alginate dressings in surgery and wound management: Part 2. J Wound Care.
Reference 3: Thomas
S., Alginate dressings in surgery and wound management: Part 3. J Wound Care.
Alginates have been shown
to be useful in a variety of situation; sloughy wounds which also produce a degree
of exudate may be dressed with alginate dressings such as Sorbsan, Tegagen, Kaltostat
(or other gel forming polysaccharide dressings). The gel which is formed as these
products absorb exudate forms a moist covering over the slough preventing it from
drying out. These dressings require moisture to function correctly, so alginates
are not indicated for dry sloughy wounds or those covered with hard necrotic tissue.
For shallow, heavily exuding wounds such as leg ulcers, fibrous sheet dressings
made from alginate fibre may be used, while cavity wounds, traditionally packed
with gauze soaked in saline, hypochlorite, or proflavine, are now more commonly
dressed with alginate fibre in the form of ribbon or rope.
wounds, alginates have an advantage over cellulose dressings in that they can
be removed without causing pain or trauma if they are first well soaked with sodium
Reference 1: [Full
Text]: Dr Stephen Thomas A structured approach to the selection of dressings,
World Wide Wounds, 1997:
Few studies mention side effects; certainly alginate
use is characterised by convenience in application and removal, as confirmed by
descriptive studies .
Foreign body reaction
One study considered
two treatment protocols for the management of patients with non-infected cavity
wounds, using data obtained from both the community and the outpatients clinic.
Patients were treated with either a polyurethane foam hydrophilic dressing (Allevyn)
or a calcium sodium alginate dressing (Kaltostat). Although alginate fibres were
found to be incorporated in tissue, both dressing regimes were found to be easy
to use, effective and acceptable to patients and clinicians .
has been one report of a florid foreign body giant cell reaction seven months
after the use of an alginate dressing to obtain haemostasis in an apicectomy cavity
on an upper lateral incisor. The case suggests that alginate fibres left in situ
may elicit a long-lasting and symptomatic adverse foreign body reaction. The authors
suggest that alginates should be reserved for problematic haemorrhage and be removed
from the tooth socket soon after haemostasis .
Dermal calcification in
Calcium alginate dressings have been used as the standard dressing
for split skin donor sites at one burn unit for 12 years. Recently, five cases
of dermal calcification in the donor site have been observed, following the use
of two new varieties of calcium alginate dressing.
Torres de Castro OG, Galindo Carlos A, Torrai Bou JE., Pure calcium-sodium
alginate dressing. Multicenter evaluation of chronic cutaneous lesions, Rev Enferm
Reference 2: Berry
DP, Bale S, Harding KG., Dressings for treating cavity wounds; J Wound Care
Reference 3: Odell EW, Oades
P, Lombardi T., Symptomatic foreign body reaction to haemostatic alginate;
Br J Oral Maxillofac Surg 1994 Jun;32(3):178-179
Reference 4: Davey
RB, Sparnon AL, Byard RW. Unusual donor site reactions to calcium alginate
dressings. Burns. 2000 Jun;26(4):393-8.
study compared four different calcium alginate dressings (Algosteril, Comfeel
Alginate, Kaltostat and Sorbsan) with respect to wound fluid retaining ability,
adherence, dressing residues, epithelialisation and inflammatory cell infiltration
using a standardised partial-thickness wound model in domestic pigs.
fluid spread laterally onto surrounding normal skin by about 40% more with Sorbsan
than with the other alginate dressings after 24h (P = 0.026). The corresponding
figure after 66h was 20% (P = 0.030). Algosteril (mean 1.7 [sem 0.3]) adhered
significantly (P = 0.014) more to the wounds than Comfeel Alginate (mean 0.2 [0.2]).
Kaltostat (mean 1.8 [0.3]) left significantly (P = 0.038) more dressing residues
on the wound surface at dressing removal than the Comfeel Alginate dressing (mean
0.8 [0.2]). In the effect on epithelialisation or dermal inflammation there was
no statistically significant difference at significance level 5% among the four
alginate dressings, as assessed by light microscopy.
In summary, the four alginate
dressings showed significant differences in important handling characteristics
but did not differ significantly in their effect on epithelialisation.
MS., Four alginate dressings in the treatment of partial thickness wounds:
a comparative experimental study; Br J Plast Surg 1996 Mar;49(2):129-134
The value of
alginates in this area has been challenged; a prospective, randomised clinical
trial to compare the effectiveness of calcium alginate swabs versus traditional
cotton swabs in the control of blood loss after extraction of deciduous teeth
included 101 healthy children, aged 3-5 years. Teeth were extracted under general
anaesthesia and blood collected for measurement in order to compare blood loss
using the two systems. The number of teeth extracted ranged from 1-14; total blood
loss ranged from 0.53-78.13 ml with a median of 12.9 ml. Calcium alginate swabs,
used in 51 subjects, were not found to produce any clinical or statistical advantage
over traditional cotton swabs .
Henderson NJ, Crawford PJ, Reeves BC., A randomised trial of calcium alginate
swabs to control blood loss in 3-5-year-old children. Br Dent J 1998 Feb 28;184(4):187-190
Alginates act as calcium ion (Ca) donors as they contain mannuronic (M)
or guluronic (G) groups with a high Ca content. A study compared the effects of
calcium and zinc containing alginates and non-alginate dressings on blood coagulation
and platelet activation to determine which was the best haemostat.
showed that alginate materials activated coagulation more than non-alginate materials.
The extent of coagulation activation was affected differently by the alginate
M or G group composition. It was demonstrated that alginates containing zinc ions
had the greatest potentiating effect on prothrombotic coagulation and platelet
Segal HC, Hunt BJ, Gilding K., The effects of alginate and non-alginate wound
dressings on blood coagulation and platelet activation. J Biomater Appl 1998 Jan;12(3):249-257
with paraffin gauze
In a prospective controlled trial, thirty patients
were randomised to the calcium alginate group and 21 to the paraffin gauze group.
The donor sites were assessed at 10 days post harvesting to determine if they
were completely healed (100%) or not. Twenty one of the patients dressed with
calcium alginate were completely healed at day 10, while only seven in the paraffin
gauze group were healed (p < 0.05). There were two infections in the study,
both occurring in the alginate group while there was no difference in dressing
slippage between the two groups.
Calcium alginate dressings provide a significant
improvement in healing split skin graft donor sites .
Compared with scarlet
Twelve paired wounds were covered with either calcium alginate or scarlet
red in seven patients with burns undergoing skin grafting. The rate of reepithelialization
was assessed by optical planimetry for the calcium alginate and by time for sloughing
of the scarlet red. This comparison failed to demonstrate objectively any difference
in the rate of wound healing between these dressings; however, calcium alginate
did significantly reduce the pain severity and was favored by the nursing personnel
because of its ease of care. Thus calcium alginate does appear to have clinical
advantages as a dressing for skin graft donor sites .
JM, O'Sullivan ST, Beausang ES et al. Calcium alginate dressings
promote healing of split skin graft donor sites; Acta Chir Plast 1997;39(2):53-55
Bettinger D, Gore D, Humphries Y., Evaluation of calcium alginate for skin
graft donor sites; Burn Care Rehabil 1995 Jan;16(1):59-61
A prospective double blind controlled trial examined the differences
in post-operative split skin graft donor site pain between sites dressed with
three differently treated types of dressing; a dry calcium alginate dressing,
a saline moistened calcium alginate dressing and a bupivacaine hydrochloride (0.5%)
moistened calcium alginate dressing.
There was a significant reduction in post-operative
pain in the calcium alginate and bupivacaine group (group 3) at 24 and 48h when
compared to the other two groups (p < 0.04). There was no difference in ease
of removal of dressings or the quality of wound healing on day 10 between the
This study suggested a significant reduction in post-operative
pain in bupivacaine soaked calcium alginate, without reducing the beneficial effects
of the calcium alginate on donor site healing .
Reference 1: Butler
PE, Eadie PA, Lawlor D, et al. Bupivacaine and Kaltostat reduces
post-operative donor site pain; Br J Plast Surg 1993 Sep;46(6):523-524
study aimed at comparing the efficacy and tolerance of an alginate wound dressing
with a parafin gauze dressing in the treatment of diabetic foot lesions, 77 patients
were enrolled, 64 completeing their treatment. Pain on dressing change was lower
in the calcium alginate group, and the total number of dressing changes was also
lower (p=0.07).The authors conluded that calcium alginate appears to be more appropriate
than parafin gauze, for topical treatment of diabetic foot lesions in terms tolerance.
Reference 1: Lalau
JD, Bresson R, Charpentier P, et al., Efficacy and tolerance of calcium
alginate versus vaseline gauze dressings in the treatment of diabetic foot lesions;
Diabetes Metab. 2002 Jun;28(3):223-9.
A prospective, randomised, controlled trial of 92 patients with full-thickness
pressure ulcers set out to compare the efficacy of an alginate wound dressing
with an established local treatment with dextranomer paste. During treatment,
a minimal 40% reduction in wound area was obtained in 74% of the patients in the
alginate group and in 42% of those in the dextranomer group. The median time taken
to achieve this goal was four weeks with alginate and more than eight weeks in
the control group. Mean surface area reduction per week was 2.39 cm2
(sd 3.54) and 0.27 cm2 (sd 3.21) in the alginate and dextranomer groups
respectively (p = 0.0001). This difference was still highly significant when the
sub-groups of almost completely healed subjects at the end of the study were considered.
This striking healing efficacy of an alginate dressing suggests it possesses
pharmacological properties which require further investigation .
1: Sayag J, Meaume
S, Bohbot S., Healing properties of calcium alginate dressings; J Wound Care
A controlled trial
set out to compare calcium alginate with the more traditional saline-soaked gauze
for packing abscess cavities, following incision and drainage. Patients were randomized
to receive either calcium alginate (16 patients) or gauze dressing (18 patients).
At the first dressing change the patient marked on a linear analogue scale the
pain experienced; the nurse noted similarly the ease of removal of the dressing.
Calcium alginate was significantly less painful to remove after operation (P
less than 0.01), and also easier to remove (P less than 0.01) than gauze dressings.
If abscess cavities are packed after incision and drainage, calcium alginate appears
to be an improvement on conventional dressings .
Reference 1: Dawson
C, Armstrong MW, Fulford SC, et al., Use of calcium alginate to pack
abscess cavities: a controlled clinical trial; R Coll Surg Edinb 1992 Jun;37(3):177-179
A study examined the CT and MR appearances
of four packing materials commonly used in otolaryngologic surgery. Bismuth and
iodoform paraffin paste, aqueous betadine gauze, calcium sodium alginate, and
triadocortyl cream were examined.
CT attenuation values were measured using
phantoms containing packing materials; MR characteristics were examined by packing
the external auditory meati of volunteers. Two illustrative case reports also
Bismuth and iodoform paraffin paste has a high CT attenuation
(> 3000 Hounsfield units) resulting in severe image degradation attributable
to streak artifact. Aqueous betadine gauze was of high attenuation (258 Hounsfield
units; SD, 16.5) but did not cause image degradation. The attenuation value of
calcium sodium alginate coincided with that of muscle, and the attenuation value
of triadocortyl creme coincided with that of fat.
On MR, calcium sodium alginate
and bismuth and iodoform paraffin paste had imaging characteristics similar to
muscle and aqueous betadine gauze had appearances similar to bone marrow. Triadocortyl
cream had a high signal equal to that of fat on T1-weighted images but a lower
signal similar to bone marrow on T2-weighted images.
The authors concluded
that the presence of bismuth and iodoform paraffin paste can give rise to clinically
important image degradation on CT. More seriously, residual packing material -
including alginate - may be misinterpreted as infection or tissue necrosis .
Hartley C, Ng KL, Jackson A., CT and MR appearance of otolaryngologic packing
materials; AJNR Am J Neuroradiol 1995 Sep;16(8):1697-1702
dressings have been employed in footcare for many years, for sinus drainage and
in the treatment of fissures, hypergranulation tissue, interdigital maceration,
heloma molle and other lesions. Alginates have been used effectively in the treatment
of diabetic and trophic foot ulcers.
Fraser R, Gilchrist T., Sorbsan calcium alginate fibre dressings in footcare;
Biomaterials 1983 Jul;4(3):222-224
Written in 1998; updated for RealNurse in July 2005 ©