% vol = 17 number = 4 prevlink = 197 nextlink = 208 titolo = "COMPARATIVE STUDY OF AQUACEL AND SILVEROL TREATMENT IN BURNS" volromano = "XVII" data_pubblicazione = "December 2004" header titolo %>
SUMMARY. We conducted a prospective study of burns treatment by Aquacel, which is a representative of the new class of absorbent dressings, compared with treatment by Silverol, a customary preparation. The study focused on the ability of these preparations to control wound infection, relieve pain, and interact with the cellular substrate of the wound. Pain intensiveness during dressing change and a half-hour later was studied according to pain scores. The bacterial contamination and infection rate was controlled by wound culture and wound inspection. The cellular substrate of the wounds was studied during at every stage of wound healing by quantitative cell investigation of the imprints from the wound surface and exudate from the wound fixated in paraffin blocks. The cooling effect of Aquacel seems very effective in pain relief and superior to pain relief after Silverol application. In reaction to wound exudates, Aquacel forms a cohesive gel sheet that provides an analgesic effect also during treatment, making it easily removable during dressing change. Microbiological study of the wounds showed minor bacterial growth on the wound surface in the early stage of treatment. Comparative results of the cytological examination of wound healing in the two groups studied revealed some similarities and differences.
Partial-thickness thermal injuries comprise the majority of burns. A superficial partial-thickness burn (SPTB) usually heals within twenty-one days unless wound infection destroys surviving epidermal adnexae in the dermis. This risk motivated the common use of topical antimicrobials for SPTB as well as for deep burns.1 Surface colonization may lead to the untreated wound invading healthy tissue. Studies report that in the past twenty-five years early surgical excision and the use of topical antimicrobials decrease the rate of infection and significantly improve the survival rate of burn victims.2 Various methods and preparations are used in the treatment of burns.
The interaction of topical preparations with the cellular wound substrate, which can lead to disturbances in wound healing, is not well known and is considered less important than prevention of infection. In addition, nearly all topical preparations need one or two painful and costly daily dressing changes.5,6 The ideal topical preparation for burns and any kind of wound should have several characteristics. It should be antiseptic and not interact with the cellular wound substrate, keep the wound wet enough for cell movement but not macerate the skin around the wound, have an anaesthetic effect, and be non-adhesive and easily removable from the wound surface. Unfortunately, no current preparations have all these characteristics and the development of more effective wound dressings is still continuing. In addition, the concept that a wound dressing should have an antiseptic effect has lately been revised. It appears that wound infection does not play an important role in small burns and does not interact with the wound healing process, even though the application of an antibacterial preparation on the wound can lead to damage of the cellular substrate or to allergic reactions.7,8 This concept made possible the development of new classes of wound dressings that do not include antimicrobial preparations in their composition, but nevertheless help promote and maintain wound repair.
Aquacel (Convatec, E.R. Squibb & Sons, L.L.C) is a representative of the new class of absorbent dressings, which achieve a moist healing environment yet avoid skin maceration, and which are convenient and cost-effective for caregivers and patients.
It is now established that a moist environment is essential for wound healing; however, this can sometimes produce excessive exudate. The protease effect of exudate may lead to cell death and impair wound healing. The challenge to be met by the dressing is therefore to remove large volumes of exudate while preserving a moist environment.
Aquacel hydrofibre is a new type of dressing. It is a hydrocolloid that offers the healing benefits of conventional hydrocolloid dressings and superior exudate management compared with other fibrous dressings. The hydrofibre in Aquacel is composed of 100% sodium carboxymethyl cellulose with a very low degree of carboxymethylation. The key feature of hydrofibre is its ability to absorb fluid directly into the body of the fibre, significantly increasing the volume of fluid that can be absorbed.10 The removal of a large volume of exudate in infected wounds may lead to a decrease in the number of micro-organisms on the wound surface.11 In the presence of wound exudate, Aquacel forms a cohesive gel sheet. This facilitates its use under compression bandages and easy removal from the wound.10 The non-adherent features of the Aquacel dressing lead to significantly less pain on changing. In the management of surgical wounds Moore showed lower pain scores among patients treated with Aquacel.12 Pain relief, local wound infection prevention, and a moist environment dictate conditions in burn management.
We conducted a prospective study of burn treatment by Aquacel compared with treatment by silver sulphadiazine 1% cream (Silverol).
The goal was to compare burn treatment by Aquacel with treatment by Silverol cream, accenting the following:
Two patient groups consisting of 11 patients each had similar burns. One group was locally treated with Silverol and the second with Aquacel. After daily patient bathing, including burn wounds, the bandages were changed. Patients were chosen randomly for each group and, after debridement of wounds from separated epidermis and fibrin, gauze pads with Silverol or Aquacel were applied. Before application on the wound surface, Aquacel was wetted with 0.9% saline solution.
Pain intensiveness during dressing change and a half-hour later was studied according to pain scores - in children over 7 yr and adults, by using visual analogue scales, and in nonverbal children, by observation of behaviour.13,14 Additionally, the rate and number of painkillers were compared to estimate the effectiveness of each method in reaching local pain relief.
Bacterial contamination and the infection rate were controlled by wound culture and wound inspection. Wound inspection was performed daily during bandage change. A microbiological investigation of the wound was conducted before the first bandage application and afterwards, weekly, until wound epithelialization. The rate of general infection was controlled by changes in the patients’ clinical status, fever, and quantity of white blood cells and platelets. With suspicion of sepsis, a blood culture was taken.
The cellular substrate of the wounds was studied during every stage of wound healing by quantitative cell investigation of the imprints from the wound surface. The technique of imprint examination consisted of burn wound drying by gauze pad from the exudate, followed by a microscope slide placed on the wound surface. The substrate affixed to the slide was dried and imprint smears were stained by the May-Gruenwald-Giemsa method. In two patients from each group, in addition to imprint examination, a 0.9% saline solution flushing from the wounds was centrifuged and the sediment, fixated in paraffin blocks, was studied by microscopy.
A cell block was prepared from wound washing sediment preserved in CytiRich® Fluid (TermoShendon). After ten minutes of centrifugation at 7000 G, the supernatant was removed and 0.5 ml plasma and 0.2 ml thrombin were added to the sediment. The formed clot was fixed in 10% formalin solution and processed for embedding in paraffin. Three µ paraffin sections were stained by haematoxylin and eosin. Immunostaining was performed on paraffin sections using the avidin-biotin peroxidase-antiperoxidase method with monoclonal antibodies for:
Evaluation of the cellular pattern was performed on May-Gruenwald-Giemsa stained cytological smears. We noted different tissue reactions (necrosis, inflammation, granulation tissue, epithelialization), their degree, and their components. Degrees for each tissue reaction fluctuated from 1 to 3. Polymorphonuclear leukocytes (PL) and histiocytes (H) or their equal amount were designated as components of inflammatory reaction; myofibroblasts (MF) alone or myofibroblasts interspersed with polymorphonuclear leukocytes (MFP) and myofibroblasts interspersed with mononuclears (MFM) as components of granulation tissue; and young and mature squamous epithelium cells as components of epithelialization.
A combination of different tissue reactions, their degree, and their cellular components designates a number of cytological patterns consisting of the following:
Twenty-two patients suffering from burns were randomly divided into two groups, eleven patients in each. In the first group, patients were locally treated with Aquacel and in the second group with Silverol. No side effects or allergic reactions from local medication were noted in patients in either group. The first group consisted of seven males and four females, the second group of six males and five females. The age of the patients in the first group was from 1.5 to 37 yr (average, 16.1 yr) and in the second group from 2 to 41 yr (average, 17.5 yr). All patients in both groups suffered from 1st-2nd degree burns over an average area of 6.9% in the first group and 7.2% in the second (Table I). Bandages were changed daily in both groups a half-hour after patients received analgesics. On the first two days pain intensity during bandage changing was high in adults and children in both groups, reaching 8-9 points, with an average of 8.6 points based upon pain scores. Immediately after bandage application, the sense of pain improved and decreased in a half-hour to 6.1 points in the Aquacel group and 6.9 points in the Silverol group. Patients in both groups required a high dose of pain relief drugs during this period. Children were treated with oxycodone syrup (Rafa Laboratories Ltd) every 8-10 h and with syrup or suppository paracetamol (Dexon) supplement taken between narcotics. Adults received a pethidine hydrochloride (Biogal Pharmaceutical Works Ltd) injection before bandage change followed by paracetamol orally as needed. Usually, from the third day, the need for narcotic analgesics dropped in both groups; for pain relief, patients received paracetamol only, with a slightly lower amount for the Aquacel group (every 10 h and every 8 h for the Silverol group). Children continued to receive narcotic medications once a day before dressing change. From the third day of treatment, pain intensity began to decline and on the fifth day it was 7-8 points (average 7.4) in both groups during dressing change. Half an hour after dressing change for the Aquacel group, pain intensity was 5.2 points and for the Silverol group 5.6 points. Additionally, in the Aquacel group, we observed less itching than usually accompanies wound healing. Wound healing in both groups was uneventful, and in the stage of advanced epithelialization patients were discharged from hospital. The average stay in the hospital for the first group was 10.2 days and for the second group 11.8 days.<% createTable "Table I ","Group characteristics according to age and total burn surface area","; Group 1;Group 2@;Local preparation;Silverol;Aquacel @;Sex;m-7 f-4;m-6 f-5 @;Age (yr);15-37 (mean, 16.1);2-41 (mean, 17.5)@;Burn TBSA (%);1.5-15 (mean, 6.9);1-14 (mean, 7.2)","",4,300,true %>
Microbiological study of the wounds showed minor bacterial growth on the wound surface in the early stage of treatment. At this stage the most common coagulase-positive and -negative staphylococci and streptococci appeared. At the end of the first week, in all wounds of both groups, more than two micro-organisms were grown. In the majority of wounds for both groups coagulase-positive and -negative staphylococci were found, accompanied by gram-negative bacteria (Escherichia coli, Klebsiella sp., Enterobacter sp., Acinetobacter sp., Pseudomonas aeruginosa, Porphyromonas). The amount of micro-organisms (i.e. the number of colonies) in the Aquacel group was higher than in the Silverol group but this did not influence the patients’ clinical status. Two patients (one in each group) developed clinical signs of sepsis and were treated by intravenous antibiotics. Blood cultures in these patients did not show bacterial growth. Both patients improved after treatment and were discharged in good condition.
An examination of the cellular substrate in the two groups now follows.
Group 1. The cellular substrate from the wound was studied in ten patients in this group. Material for examination was obtained before application of Aquacel (0-4 days post-burn), after the first Aquacel application (5-10 days post-burn), and after the second Aquacel application (11-20 days post-burn).
Before application of Aquacel, a smear sufficient for examination was found in nine out of the ten patients. In one patient, all cells showed necrotic changes (pattern I). Pattern II was found in five patients, pattern III in two, and pattern IX in one. The cellular substrate in two out of the five patients with pattern II had an equal proportion of viable and necrotic inflammatory cells and, in one case, PL predominated over H; in another case, PL and H were in equal amounts. In three out of the five patients, viable PL and H predominated over necrotic PL; in two, PL predominated and, in the third, PL and H were in about equal amounts. In one of the two patients with pattern III, PL predominated; in the other one, PL and H were in about equal amounts. In the patient with pattern IX, a predominant epithelial component was intermixed with small amounts of MF, MFM, and PL.
A cell block showed cellular debris and inflammatory exudates of polymorphonuclear leukocytes in both cases, with enucleated squames and a little mononuclear cell admixture.
Immunohistochemical stains revealed MMP-10 immunostain positive in polymorphonuclear leukocytes, very weak in some anucleated squames and negative in mononuclears and cellular debris; MMP-3-immunostaining and mast cell tryptase-immunostain-negative.
After the first Aquacel application (6-9 days post-burn), the smear was found to be sufficient for examination in eight out of the ten patients. Pattern IV was found in two patients, pattern V in two, pattern VI in two, and pattern VIII in two. In two patients with pattern IV, PL and H in equal amounts predominated over MFM. In two patients with pattern V, granulation tissue contained MF and MFM with few PL or H admixed. Small fragments of connective tissue amorphous basal substance were also present. In two patients with pattern VI, a few YSC were admixed in granulation tissue composed of MF and MFM. In two patients with pattern VIII, the predominant epithelial component composed of YSC was associated with histiocytes.
A cell block presented, consisting predominantly of squamous cells with different grades of maturity (young, mature, and anucleated squames) and, in one case, of small amounts of cellular debris and inflammatory cells.
Immunohistochemical stains revealed MMP-10 immunostain positive in polymorphonuclear leukocytes (one case) and weak positive in all kinds of squamous cells (YSC, MSC, and enucleated squames); MMP-3-immuno-stain and mast cell tryptase-immunostain-negative.
After the second Aquacel application (11-20 days post-burn), the smear was found to be sufficient for examination in two of the three cases studied. In one of these patients studied on day 11 post-burn (7 days after application), the smear showed pattern V, consisting of MF and MFM. The second patient, studied on day post-burn (20 days after application), displayed pattern IX with YSC predominance associated with few MFM and PL.
Group 2. Nine patients were studied in this group. Material for examination was obtained before application of Silverol (1-4 days post-burn), after the first Silverol application (5-10 days post-burn), and after the second Silverol application (16-17 days post-burn).
Before application of Silverol, a smear sufficient for examination was found in seven of the nine patients. In five of these seven patients, pattern II was found, in one patient pattern III, and in one patient pattern VIII. In four out of these five patients with pattern II, viable (PL in three and H in one) and necrotic inflammatory cells were found in equal amounts. In one of these five patients viable PL were a predominant component. In one patient with pattern III, viable PL were the sole components of the smear. In one patient with pattern VIII, the inflammatory component composed of H was predominant, and was associated with MFM of granulation tissue and YSC.
Cell block consisted of more massive cellular debris in one case, with amounts of inflammatory cells (mononuclears and polymorphonuclear leukocytes) and some squamous cells (young and enucleated squames) in another.
Immunohistochemical stains revealed MMP-10 immunostain positive in polymorphonuclear leukocytes, weak positive in mononuclears (one case) and negative in anucleated squames (one case) and cellular debris; MMP-3-immunostain and mast cell tryptase-immunostain-negative in all kinds of cellular material.
Following the first Silverol application (5-10 days post-burn), a smear sufficient for examination was found in all nine patients. Pattern VI was present in two patients, pattern VII in four, and pattern IX in three. In two patients with pattern VI, the granulomatous component composed of MF was predominant. The inflammatory component was composed of H and some PL. YSC were occasionally present. In four patients with pattern VII, YSC only were found in two patients; a combination of YSC and MSC was found in two patients. In three patients with pattern VIII, the predominant epithelial component was composed of MSC. The granulomatous component was composed of MF. A similar proportion of H and PL presented an inflammatory component.
Cell block consisted of squamous cells (mature and enucleated squames) that were total in one and predominant in a second case; a small amount of cellular debris with inflammatory cell admixture was present in the second case.
Immunohistochemical stains revealed MMP-10 immunostain strong positive in mature squamous cells (two cases), in polymorphonuclear leukocytes and mononuclears (one patient) and weak positive in enucleated squames. MMP-3-immunostain and mast cell tryptase-immunostain were negative.
After the second Silverol application (16-17 days post-burn), a smear sufficient for examination was found in both cases studied. Pattern VI was found with granulation tissue composed of MF; the epithelial component was presented by YSC in one patient and by YCS and MSC in the second.
The majority of burn-injured patients suffer from partial-thickness burns. The local treatment of patients with superficial burns is still controversial. According to modern concepts, wound care preparation for local treatment should have several characteristics. It should be antiseptic but not interact with cellular wound substrate, keep the wound wet enough for cell movement but not macerate the skin around the wound, have an anaesthetic effect, and be non-adhesive and easily removable from the wound surface.
Aquacel is representative of a new class of preparations for local wound and burn treatment. Wetting Aquacel with saline solution converts it for gel substance chilling (cooling) of the wound surface. Cooling by Aquacel seems very effective in pain relief and superior to pain relief after Silverol application. In reaction to wound exudates, Aquacel forms a cohesive gel sheet that provides an analgesic effect and becomes easily removable during dressing changes.
Aquacel has no antimicrobial preparation in its composition but, as Brånvall showed, removal of a large volume of exudates in infected wounds may lead to a decrease in the number of micro-organisms on the wound surface.11 We observed a larger number of micro-organisms vegetating on the wound surface of Aquacel-treated patients than in the Silverol group, without the occurrence of more infectious complications. One patient in each group developed clinical features of generalized infection that required systemic antibacterial treatment.
Comparative results of the cytological examination of wound healing in the two groups of patients revealed some similarities and differences. Before application of Aquacel or Silverol, different patterns of wound status were detected in both groups. The most frequent (five cases) was pattern II - predominant inflammation associated with destruction of some inflammatory cells (necrosis). Less frequent was pattern III - viable inflammatory cells. The number of cases where the inflammatory component predominated was slightly higher in the Silverol group (six out of seven cases) than in the Aquacel group (seven out of nine).
The inflammatory reaction is known to play a significant role in wound healing by the absorption of cellular debris and by the secretion of different substances promoting migration, proliferation, and differentiation of various cellular subsets. Consequently, the inflammatory reaction may be a factor predicting stimulation of all these stages in the wound healing process in patients in the Silverol group. In one patient in the Aquacel group, nearly all the inflammatory cells underwent necrotic changes, with components negatively influencing wound repair. Examination of cell block preparations in patients before Silverol or Aquacel application revealed similar findings - cellular debris, inflammation, and enucleated squames. Occasional YSC were found in one patient in the Silverol group. Strong MMP-10-immunostaining was detected in polymorphonuclear leukocytes. Mononuclears and enucleated squames showed weak MMP-10-immunostaining. Cellular debris was negative. The inflammatory reaction was present in more patients in the Silverol than in the Aquacel group. The absence of necrosis and identification of YSC in the cell block of some patients in the Silverol group, before application, may possibly predict more successful wound healing in more patients in the Silverol group.
In patients in group 1, after Aquacel application I (6-9 days post-burn), several cytological patterns - pattern III, pattern IV, pattern VI, pattern VII - were found. Two patterns - pattern III and pattern IV - were free of epithelial components. In contrast, in patients in group 2, after Silverol application II (5-10 days post-burn), the smears of all patients showed epithelial cells (patterns VI, VII, VIII, IX). Squamous epithelial cells were a sole or a predominant component of the smear in five out of the nine patients in the Silverol group; in the Aquacel group, the smears of only two out of the eight patients studied were entirely or predominantly epithelial.
Examination of the cell block 6-10 days post-burn did not reveal significant differences in the Aquacel and Silverol groups. There were predominantly squamous cells in some patients or small amounts of cellular debris and inflammatory cells admixed with a predominant presence of squamous cells. MMP-10-immunostaining of cell block cellular components 6-9 days after Aquacel application resembled the pattern before application. More intensive MMP-10-immunostaining of MSC and mononuclears were found 5-10 days after burn in the Silverol group than in the Aquacel group. There were more patients with epithelial repair, according to cytological findings, owing perhaps to the shorter interval between the application and specimen preparation in the Aquacel group (7.1 days in the Aquacel group and 7.7 days in the Silverol group).
MMP extracellular proteins play an important role during epithelialization of the wound. Wound re-epithelialization was found to be associated with the active production of collagenase, 92-kDa gelatinase, and MMP-3 and MMP-10 by distinct subpopulation of keratinocytes at the migrating border.
An increased level of MMP is associated with tissue degradation and remodelling during wound healing. There is evidence that cell interactions between fibroblasts and keratinocytes lead to an increase in metalloproteinase production. In normal epithelium, the extracellular matrix metalloproteinase inducer was found. It stimulates production of interstitial collagenase, gelatinase A, and MMP-3 by fibroblasts. This ability may be involved in the regulation of matrix remodelling of the epidermal-dermal interface.17 In situ hybridization and immunohistochemistry studies revealed that distinct populations of keratinocytes in a variety of chronic ulcers produce MMP-3 and MMP-10. MMP-3 was detected in basal keratinocytes, which probably re-present the site of the proliferating epidermis. In contrast, MMP-10 was seen in only the basal front in some epidermal cell populations that expressed collagenase. MMP-3-producing keratinocytes resided on the basement membrane, whereas MMP-10-producing keratinocytes in contrast were in the dermal matrix.18 MMP over-expression can lead to tissue destruction, which is characteristic of chronic inflammatory diseases such as rheumatoid arthritis and scleritis.
In two patients in the Silverol group (12 and 13 days after the second Silverol application), the smears were examined 16 and 17 days post-burn and found to show a completely similar cytological pattern - i.e. the presence of granulation tissue with YSC admixture. In the Aquacel group, the cytological pattern was different in two patients. Granulation tissue was found only in the smear of a patient studied 11 days post-burn (7 days after Aquacel application). Retardation of epithelial repair in this case may be explained by the short interval between the burn and the smear, also resulting from the short period of treatment by Aquacel application. In the second patient, the smear was obtained 20 days post-burn (and 20 days after Aquacel application); it consisted predominantly of epithelial cells and a small amount of granulation tissue and inflammatory cells.
Consequently, many patients in the Silverol group before application had a slightly better cytological pattern of the wound than patients in the Aquacel group. Several days after Silverol application, the differences in wound healing persisted. The appearance of moderately MMP-10-positive squamous cells 5-10 days post-burn in the Silverol group may reflect wound repopulation by the collagen-expressing subpopulation of squamous cells,15 an event that did not occur after Aquacel application. Slightly more advanced epithelial repair in patients with Silverol application is associated not only with a better cytological pattern before treatment but also with a relatively short period of treatment in patients with Aquacel treatment. In the long run, the duration of the wound was found to be a more important factor in healing than the kind of material applied.
Aquacel is a new preparation for burn treatment. It is convenient for patients and caregivers. Its pain relief effect is superior to that of Silverol. The antimicrobial influence of Aquacel is not as strong as that of Silverol, but in small area burns both Silverol and Aquacel prevent dissemination of infection in the same manner. Aquacel interacts less with the cellular substrate than Silverol.
RESUME. Les Auteurs ont effectué une étude prospective du traitement des brûlures avec Aquacel, qui est représentatif de la nouvelle classe de pansements absorbants par rapport au traitement avec Silverol, une préparation traditionnelle. Les Auteurs ont concentré leur attention sur la capacité de ces préparations de régler l’infection des lésions, de soulager la douleur et d’interagir avec le substrat cellulaire de la lésion. Ils ont étudié l’intensité de la douleur pendant les changements des pansements et une demi-heure après, utilisant les scores de la douleur. Le taux de contamination bactérienne et d’infection a été vérifié moyennant la culture et l’inspection des lésions. Le substrat cellulaire des lésions a été étudié pendant toutes les phases de la guérison des lésions moyennant l’investigation quantitative cellulaire des empreintes de la surface de la lésion et de l’exsudat de la lésion fixées dans des blocs de paraffine. L’effet refroidissant de l’Aquacel semble être très efficace pour ce qui concerne le soulagement de la douleur et supérieur à celui obtenu avec l’application de Silverol. Réagissant aux exsudats des lésions, l’Aquacel forme une couche cohésive de gel qui exerce un effet analgésique même pendant le traitement, ce qui le rend facile à enlever pendant les changements des pansements. L’étude microbiologique des lésions a démontré une croissance mineure sur la surface des lésions pendant les premières phases du traitement. Les résultats comparatifs de l’examen cytologique de la guérison des lésions dans les deux groupes ont révélé des ressemblances et des différences.