Bums (1992) 18,Supplement 2, S15-,518
SlS
Printed in Great Britain
Treatment of burns with occlusive dressings: some pathophysiological and quality of life aspects M. H. E. Hermans ConvaTec
International,
Skillman, New Jersey, USA
Introduction The earliest indications of mankind’s interest in the treatment of wounds goes back to the EgyptiansThe Papyrus Ebers Papers (Anonymous, 1700 BC) indicate that wounds were treated with frogskin or greased bandages. More recently other materials have been used, including tinctures and extracts, dressings soaked in vinegar, pressure dressings, boric lint, and carbolic dressings (Wong, 1980). The concept of the greased bandage is, to a large extent, similar to the bandage that is still most commonly used, the tulle gras (cotton impregnated with paraffin) which was first described by Lumiere during the Second World War. Also during this war the principles of tanning were described (Wallace, 1941) for larger bums. The first synthetic material, methylcellulose, became available in 1942 (Pickwell, 1942), followed by hydroxyethyl methacrylate in 1960 (Wichterie and Lim, 1962), and polyvinyl alcohols in 1962 (Chardack et al., 1962). The use of all these materials was based on the feeling that a wound had to be physically protected from the influences of external forces or agents (Bishop, 1960). Winter (1963) took the first steps to an explanation of why protection is so important for wound healing. Recent advances in understanding the dynamics of the wound-healing process have lead to the development of many new materials for the treatment of wounds; most of them are based on the principles of occlusion. This article describes some of the pathophysiological and quality of life advantages of occlusive dressings.
Prevention
of desiccation
of the wound bed
The importance of desiccation, which, in a wound, leads to scab formation, was demonstrated in animal experiments in which wounds were occluded or left exposed to the air. The scab that formed in the open wounds decreased the migration possibilities of keratinocytes, resulting in impaired wound healing (Winter, 1963). This general phenomenon turns out to be particularly important in partial skin thickness burns, If the zone of delayed stasis, which, in a burn wound, surrounds the central necrotic zone, is protected from desiccation, hair follicles and other remnants of the skin remain viable and form a focus from which wounds heal (Zawacki, 1974a,b). Wounds which are occluded with a material with a sufficiently low moisture vapour transmis10 1992 Butterworth-Heinemann 0305-4179/92/S2OS15-04
Ltd
sion rate (MVTR) do not dry out and this allows the tissue to retain its viability. It has been shown that conventional materials like tulle gauze have an MVTR which is too high (Jo&man, 1989). The ideal MVTR for a dressing is still an open question. Semipermeable materials (such as films) and impermeable materials (such as some hydrocolloids) all prevent desiccation of the wound (Hinman and Maibach, 1963; Alper et al. 1983; May, 1983; Hermans and Hermans, 1986), in spite of the differences in their MVTR.
Mechanical effects of a dressing wound bed
on the
Some dressings adhere to the wound bed so firmly that removing them leads to destruction of vital tissues or removal of newly grown epithelium. This impairs the wound healing process. Mechanical disturbance can regularly be observed when gauze-type materials are used. Bleeding of the wound bed and the pain during removal are both signs of mechanical damage (Winter, 1970). Sometimes tissue can even be found in the tulle (Gillman, 1970). Occlusive materials usually do not damage the wound bed upon removal because the moisture film between the dressing and the wound bed prevents firm adhesion to tissues.
(Bio)chemical wound bed
effects of a dressing
on the
Cotton-based materials can induce ‘biochemical disturbance’ to the wound: they may induce foreign-body reactions with giant cells and hyperinflammation (Gillman, ‘1970) or granulomas (Woods, 1976). Antiseptics are also known to disturb the wound healing process. Although some of these materials are only mildly cytotoxic (Ray et al., 1988), all of them do impair the tissue repair process, which results in a decrease in the rate of epithelialization (Monafo and Ayvazian, 1978; Bolton et al., 1985; Warden, 1987). Careful attention must be paid to indications for these agents; if they are not indicated they should not be used ‘as a precaution’ because they may have detrimental effects on cell growth (Cooper et al., 1991) or even cause severe systemic effects (Rath and Meissl, 1988).
Burns (1992) Supplement 2
S16
Occlusive materials usually are made out of synthetic constituents. with minor or non-existent side-effects; some of them produce a wound environment that, in itself, allows for optimal antimicrobial activity of the host defense cells (May, 1984; Varghese et al., 1988); hence, the use of local antimicrobials is quite often not necessary. pH and temperature The pH that exists in and above a wound has been shown to have an influence on tissue repair. A slightly acidic pH, as is provided by some of the occlusive materials, has mild antibacterial effects (Mertz et al., 1985; Katz et al., 1986; Mulder et al., 1989). Moreover, wounds that are exposed to air rapidly lose CO, and develop a local respiratory alkalosis which may lead to healing failure (Leveen et al., 1973). In an occlusive environment the pH can be controlled in a more secure way than in a non-occlusive environment in which exchange of gases and fluids between the wound surface and the atmosphere is possible (Leveen et al., 1973). The local temperature is somewhat higher in an occlusive environment which speeds up the healing rate of wounds (Gimbel and Farris, 1966; Leveen et al., 1973). In larger wound surfaces, occlusion may help in reducing the respiratory and metabolic effects of hypothermia (Dill and Forbes, 1941; Hemdon et al., 1987).
Infection and wound healing A literature survey has shown that the overall infection rate under occlusive dressings is lower than under conventional dressings (Hutchinson, 1989). In other studies it has been shown that Psetld. aentginasa disappears in a moist wound environment (Gillchrist and Reed, 1989) as provided by some dressings, and that wounds do heal in spite of their heavy and unchanging bacterial contamination (Gillchrist and Reed, 1988). A possible explanation for these phenomena may be found in the availability of polymorphonuclear cells (PMN): in wounds covered with an occlusive material the number of these cells is very high (Buchan et al., 1981), whereas, in the presence of a scab, the number of PMNs is decreased (Falanga, 1988). PMNs are likely to be the most important defence against infection and the ability of these cells to enter the wound site is therefore crucial. It has been shown that the activity of PMNs in fluid collected from skin lesions, treated with occlusive materials, is at least as high as that in autologous blood (Katz et al., 1986). Studies on PMNs, obtained from occluded wounds, have demonstrated the presence of stainable bacterial inclusions (May, 1983; Varghese et al., 1986): this suggests previous ingestion of bacteria. Dressings also can provide a barrier for microorganisms. A physical barrier against bacterial invasion exists in some of the occlusive dressings (Lawrence and Lilly, 1988). This helps to diminish the overall bacterial load with which the host defense mechanisms have to deal. One of the ‘side-effects’ of the viability of the PMNs and the macrophages is the autolytic debridement that occurs in an occlusive environment: this speeds up ‘preparation of the wound bed for re-epithelialization.
Quality of life Bumwounds are extremely painful and so are donor sites. When choosing treatment may sufficiently.
local wound treatments, the pain such a cause is not always taken into account
An occlusive wound environment offers excellent pain relief in many types of wounds (Donati and Vigano, 1988; Fechner and Kon, 1988; Hedman, 1988; Sayers and Porter, 1988; Waffle et al., 1988) possibly because the nerve endings are prevented from desiccation. Patient comfort is also enhanced when personal hygiene (showering, bathing) and other activities of daily living are not hampered. Some these benefits (Hermans and van dressings provide Wingerden, 1990). The long-term results of bum wound healing are very important: cosmetically unacceptable scars are still a major problem in bum care and may have a severe impact on the quality of life. Hypertrophic scarring is probably the single most important long-term cosmetic problem. Many hypotheses have been developed on the actual cause of hypertrophic scarring. Collagen deposition (Efting Dykstra, 1977) and myofibroblasts (Baur et al., 1975) are important, but to date a completely satisfactory explanation has not been found. Treatment of hypertrophic and keloid scars is even more controversial (Peacock, 1983) although the use of pressure garments or silastic sheets (Afin et al., 1989) is accepted as ways to reduce the scars. This type of therapy, which is expensive and uncomfortable for the patient, will not result in a complete disappearance of the scars. Reducing the chances of hypertrophic scar development is extremely important. One probable way of reducing the incidence of these scars is by the use of occlusive materials (Leveen et al., 1973; Tjong Wai et al., 1983; May et al., 1984; Eisenberg, 1986; Hermans and Hermans, 1986; Hoekstra, 1990).
Cost-effectiveness Many clinicians consider modem occlusive materials to be too expensive. The price per unit of occlusive dressings may be higher than those of conventional dressings, but the overall costs of treatment are not determined by the primary dressing alone. Additional costs may include fixation bandages and other miscellaneous materials such as gloves. The wearing time of a dressing influences the number of dressing changes and the nursing time involved. Healing time of a wound has a serious effect on the hospitalization time, and therefore on the overall cost of a particular treatment. For chronic lesions (leg ulcers; Harkiss, 1985) and for bums (Hermans, 1990) it has been shown that occlusive materials can be more cost effective than conventional materials. As the healing time of a wound usually is much shorter when occlusive therapy is used (Winter, 1963; May, 1984; Hermans, 1987; Donati and Vigano, 1988), cost differences probably would have been even more dramatic had hospital costs been calculated in these studies.
Indications There are many excellent classifications available for wound dressings (Guldalian et al., 1973; Queen et al., 1987) and this article is not meant to make another one. Therefore, only some indications and contraindications for occlusive materials are given below. Full skin-thickness burns A. In relatively large full skin thickness bums hardly any indication exists for the current synthetic materials. Only when excision is performed without grafting of all the excised areas, some occlusive materials may be used. These should be synthetic or biological materials that (firmly) adhere to the wound bed to provide protection
Hermans: Treatment of burns with occlusive dressings
against desiccation and contamination. All these materials are known to block re-epithelialization, however. In the sandwich (Alexander et al., 1981) or intermingled (Yang et al., 1980) techniques allografts play a crucial role; they provide coverage of the interstices and serve as a scaffold for migration of the keratinocytes from the autografts. B. Only very small full skin thickness bums (maximum 3-5 cm in diameter) may be treated without excision and grafting. Even then, healing will be slow but, often, satisfactory (Hermans and Hermans, 1988). Partial skin thickness
burns
A. Most of these bums are not life threatening because they are fairly small. The primary aim in the treatment of these bums is to restore cosmetically good skin. It is here that the use of occlusive dressings, whether biological or (semi) synthetic, is most indicated. 1. Biological materials, such as allografts, amnion, and, to a lesser extent, xenografts, have the advantage of adhering to the wound bed and, in most cases, they remain adherent until the wound underneath is healed. They block the formation of exudate. The materials may transfer diseases from the donor to the acceptor. In particular the allografts are capable of transferring viral diseases such as hepatitis and AIDS, although some preservation methods seem to be able to inactivate viruses and kill bacteria (Hoekstra et al., 1990). Rejection of biological dressings may be a problem and storage and availability is relatively complicated. Cosmetically, excellent results have been described (Tjong Wai et al., 1983; Eisenberg, 1986). Less common biological materials for the treatment of partial skin thickness bums are hen-egg membranes, banana leaves, potato peels, and multiple collagen films. With all of them good results have been described. Z. (Semi)synthetic materials. The number of (semi)synthetic
dressings has grown extensively during recent years. Theoretically, most materials offer a wound environment which is beneficial to the local wound healing process. Clinically there are major differences in performance of the materials, even within subgroups that are claimed to have similar properties. For many occlusive dressings pain relief is claimed to be good (Donati and Vigano, 1988; Fechner and Kon, 1988; Hedman, 1988; Sayers and Porter, 1988; Waffle et al., 1988), as are the speed of re-epithelialization and patient comfort. They
are readily
available
and easy to store.
The main advantage of synthetic over biological dressings is their ease of use: not much specific knowledge is required. Donor
sites
Most donor sites are very painful, but they do not cause healing problems. For most occlusive dressings clinical trials have been done with donor sites, and most of them with excellent results (Madden et al., 1985; Donati and Vigano, 1988; Fechner and Kon, 1988). Practical problems may occur for donor sites that are surrounded by grafted or burned areas; those occlusive dressings that require normal skin around the wound to adhere to cannot be used. Donor site treatment may then interfere with the other local treatment regimens.
s17
Conclusion In recent years, evidence that managing wounds with occlusive dressings offers many advantages has grown substantially. Although the treatment of full skin thickness bums has not yet acquired much from this evidence, it has been shown that partial skin thickness bums, which form the majority of all bum cases, really can gain from the use of occlusive dressings, because these materials provide fast re-epithelialization with low incidence of infection and good cosmetic results. In addition to the medical benefits observed, patient quality of life is increased and treatment costs reduced. It should be realized, however, that not all occlusive materials, not even all materials in one subgroup, share the same properties; this may result in clinically different properties (Lawrence and Lilly, 1988). It is therefore very important to only use materials that have been clinically tested for a particular indication (Bolton and Rijswijk, 1991).
References AhnS. T., Monafo W. W. and
Mustoe T. (1989) Topical silicone gel: a new treatment for hypertrophic scars. Surgery 10, 781. Alexander J. W., MacMillan B. G., Law E. et al. (1981) Treatment of severe bums with widely meshed skin autograft and meshed skin allograft overlay. 1. Trauma 21, 433. Alper J. C., Welch E. A., Ginsberg M. et al. (1983) Moist healing under a vapour permeable membrane.]. Am. Acad. Dem. 8,347. Anonymous (1700 Bc) Papyrtrs Smith Papers. Baur P. S., Lason D. L. and Stacey T. R. (1975) The observation of myofibroblasts in hypertrophic scars. Surg. Gynecol. Obstef. 141, 22. Bishop W. J. (1960) Be Early Hisfory of Surgery. Worcester and London: Ebenezer Baylis and Sons Ltd, The Trinity Press. Bolton L. and van Rijswijk L. (1991) Wound dressings: meeting clinical and biological needs. Dermatol. Nut-s. 4, 146. Bolton L., Oleniacz W., Constantine B. et al. (1985) Repair and antibacterial effects of topical antiseptic agents. In: Maibach H. and Lowe N. (eds), Models in Dermatology. Karger, BaseI: Maibach and Lowe, p. 145. Buchan I. A., Andrews J. K., Lang S. M. et al. (1981) Clinical and laboratory investigation of the composition and properties of human skin wound exudate under semi permeable dressings. Burns 7,326. Chardack W. M., Brueske D/A., Santomauro A. P. et al. (1962) Experimental studies on synthetic substitutes for skin and their use in the treatment of bums. Ann. Swg. 155, 1.27. Cooper M. L., Laxer J. A. and Hansbrough J. (1991) The cytotoxic effect of commonly used topical antimicrobial agents on human fibroblasts and keratinocytes. 1. Truumn 31, 775. Dill D. B. and Forbes W. H. (1941) Respiratory and metabolic effects of hypothermia. Am. J Physiol. 132, 685. Donati L. and Vigano M. (1988) Use of the hydrocolloidal dressing DuoDERM for skin donor sites for bums. hf. 1. Tissue Reacfions 4, 267. Efting Dykstra J. D. (1977) Littekenvonning. Thesis, Meppel, Netherlands: Krips Repro. Eisenberg M. (1986) The effect of occlusive dressings on reepithelialization of wounds in children with epidermiolysis bullosa. I. Pediafr. Surg. 21, 892. Falanga V. (1988) Occlusive wound dressings. Arch. Dematol. 124,872.
SlS Fechner M. R. and Kon M. (1988) De behandeling van donorplaatsen van huidtransplantaten met polyvinylhydrogelfolie. Ned. Tijdschr. Geneeskd. 25,1174. Gillchrist B. and Reed C. (1988) The bacteriology of leg ulcers under hydrocolloid dressings. In: Ryan T. J. (ed.), Beyond Occlusion, Woundcare Proceedings. R. Sot. Med. 136,83. Gillchrist B. and Reed C. (1989) The bacteriology of chronic venous ulcers treated with occlusive hydrocolloid dressings. Br. 1. Dermatol. 4, 337. Gillman T. (1970) Outline of some aspects of the healing of full thickness loss excised wounds. In: Had&s K. J. (ed.), Surgical Dressings and Wound Healing. Bradford: University Press, p. 98. Gimbel N. S. and Farris W. (1966) The influence of surface temperature in the epithelialisation rate of split thickness donorsites. Arch. Surg. 92, 554. Guldalian J., Jelenko C., Callaway D. et al. (1973) A comparative study of synthetic and biological materials for wound dressings. 1. Traum 13,32. Harkiss K. (1985) Cheaper in the long run. Community O&look
124,872. Hedman L. A. (1988) Effect of a hydrocolloid dressing on the pain level from abrasions on the feet during intensive marching. Milit. Med. 153, 188. Hermans M. H. E. (1987) Hydrocolloid dressing (DuoDerm) for the treatment of superficial and deep partial thickness bums. Stand. 1. Plast. Reconstr. Surg. 21,283. Hermans M. H. E. (1990) The role of hydrocolloid dressings in modem wound care. Trauma 1. Accid. Emerg. Med. 6, 12. Hermans M. H. E. and Hermans R. I’. (1986) DuoDerm, an alternative for the treatment of smaller burns. Burns 12,214. Hermans M. H. E. and van Wingerden S. (1990) Treatment of industrial wounds with DuoDERM bordered: a report on medical and patient comfort aspects. 1. Sot. Occq Med. 40, 3. Treatment of Herndon D. N., Curreri I’. W., Abston S. et al. (1987) bums. In: Ravitch M. M. (ed.), Currenl Problems in Surgery. Medical Publishers, p. 347 Hinman C. D. and Maibach H. (1963) Effect of air exposure and occlusion on experimental human skin wounds. Nature 200, 377. Hoekstra M. J. (1990) Specisle behandelingen van brandwonden. In: Hermans M. H. E. (ed.), DuoDERM Symposium Proceedings. Amsterdam: Excerpta Medica, p. 111. Hoekstra M. J., Buttenwerf J., Kreis R. W. et al. (1990) Cadaverskin and viruses. Proceedings of the 8th International Congress on Bum Injuries, New Delhi, India, p. 179. Hutchinson J. J. (1989) Prevalence of wound infection under occlusive dressing: a collective survey of reported research. Wounds 1, 123. Jo&man M. F. (1989) Epiderrnal Wound Healing betzoeen Moist and Dy Dressing. (Thesis). Groningen: Groningen University Press. Katz S., McGinley K. and Leydon J. J. (1986) Semipermeable occlusive dressing. Effect on growth of pathogenic bacteria and reepithelialisation of superficial wounds. Arch. Dermatol. 122,
58. Lawrence J. C. and Lilly H. A. (1988) Bacterial barrier properties of hydrocolloid dressing in vitro. In: Ryan T. J. (ed.), Beyond Occlusion, Wound Care Proceedings. R. Sot. Med. 136,75. Leveen H. H., Falk G., Borek B. et al: (1973) Chemical acidification of wound: an adjuvant to healing and the unfavourable action of alkalinity and ammonia. Ann. Surg. 138, 745. Madden M. R., Finkelstein J. L., Hefton J. M. et al. (1985) Optimal healing of donor sites with hydrocolloid dressings. In: Ryan T. J. (ed.), An Environmenl for Healing. R. Sot. Med. 136,133.
Bums(1992)Supplement2 May S. R. (1983) Physiological activity from an occlusive wound dressing. In: Lawrence J. C. (ed.), Wound Healing Symposium. Oxford: Medical Publishing Foundation, p. 35. May S. R. (1984) Physiology, immunology and clinical efficacy of an adherent polyurethane dressing: Opsite. In: Wise L. W. (ed.), Burn Wound Coverings, vol. II. Boca Raton, FL: CRC Press, p. 53. Mertz P. M., Marshall D. and Eaglstein W. H. (1985) Occlusive wound dressing to prevent bacterial invasion and wound infection. J. Am. Acad. Dematol. 12,662. Monafo W. W. and Ayvazian V. H. (1978) Topical therapy. Surg. Clin. North Am. 6, 1157. Mulder G. D, Kissil M. T. and Mahr J. J. (1989) Bacterial growth under occlusive and non-occlusive wound dressing. Wounds 1, 63. Peacock E. E. Jr (1983) Pharmacological control of surface scarring in human beings. Ann. Surg. 193,592. Pickerel1 K. L. (1942) A sulphonamide film for use as a surgical dressing. Bull. ]ohn Hopkins Hosp. 71, 304. Bums wound Queen D., Evans J. H., Gaylor J. D. S. et al. (1987) dressings - a review. Burns 13,218. Rath Th. and Meissl G. (1988) Induction of hyperthyroidism in bum patients treated with povidone-iodine. Burns14,320. Ray M., San J. and Antonys G. L. (1988) Tolerance and therapeutic efficacy of topically applied SSD cream in infected wounds. Curr. 7’her. Res. 43,1025. Sayers R. and Porter K. M. (1988) Comparison of DuoDERM and medicated tulle-gras in the treatment of fingertip-injuries. In: Ryan T. J. (ed.), Beyond Occlusion, Woundcare Proceedings. R. Sot. Med. 136,133. Tjong Wai R., Kreis R. W. and Hermans R. P. (1983) Resultaten van de behandeling met allogene huidtransplantaten van verbranding door hete vloeistoffen bijn kinderen. Ned. Tijdschr. Geneesk. 290. Varghese M. C., Balin A. K., Carter D. M. et al. (1986) Local environment of chronic wounds under synthetic dressings. Arch. Dermatol. 122,52. Waffle C., Simon R. R. and Jo&n C. (1988) Moisture vapour permeable film as an outpatient bum dressing. Burns 14,66. Wallace A. B. (1941) The Treatment of Burns. Oxford War Manuals. London: Humphrey Milford. Warden G. D. (1987) Outpatient management of thermal injuries. Bull. Burn lnj. 30. Wichterie 0. and Lim D. (1962) Hydrophilic gels for biological use. Nature 185, 117. Winter G. D. (1963) Effect of air drying and dressings on the surface of a wound. Nature 197,91. Winter G. D. (1970) Healing of skin wounds and the influence of dressings in the repair process. In: Harkiss K. J. (ed.), Surgical Dressings and Wotind Healing. Bradford: Bradford University Press, pp. 46-51. Wong P. (1980) Physical evaluation of hydrogel as a bum wound dressing. M.Sc. Thesis, University of Strathclyde. Woods R. A. B. (1976) Disintegration of cellulose dressings in open granulating wounds. Br. Med. J 1444. Yang C. C., Shih T. S., Chu T. A. et al. (1980) The intermingled transplantation of auto and homografts in severe bums. Burns 6,
141. Zawacki B. E. (1974a) The natural history of reversible burn injury. Surg. Gynecol. Obstet. 139,867. Zawacki B. E. (1974b) Reversal of capillary stasis and prevention of necrosis in burns. Ann. Surg. 139,98. Correspondence should be addressed lo: Dr M. H. E. Hermans, Director Medical Development, ConvaTec International, 200 Headquarters, Park Drive, Skillman, NJ 08558, USA.
SlS
Printed in Great Britain
Treatment of burns with occlusive dressings: some pathophysiological and quality of life aspects M. H. E. Hermans ConvaTec
International,
Skillman, New Jersey, USA
Introduction The earliest indications of mankind’s interest in the treatment of wounds goes back to the EgyptiansThe Papyrus Ebers Papers (Anonymous, 1700 BC) indicate that wounds were treated with frogskin or greased bandages. More recently other materials have been used, including tinctures and extracts, dressings soaked in vinegar, pressure dressings, boric lint, and carbolic dressings (Wong, 1980). The concept of the greased bandage is, to a large extent, similar to the bandage that is still most commonly used, the tulle gras (cotton impregnated with paraffin) which was first described by Lumiere during the Second World War. Also during this war the principles of tanning were described (Wallace, 1941) for larger bums. The first synthetic material, methylcellulose, became available in 1942 (Pickwell, 1942), followed by hydroxyethyl methacrylate in 1960 (Wichterie and Lim, 1962), and polyvinyl alcohols in 1962 (Chardack et al., 1962). The use of all these materials was based on the feeling that a wound had to be physically protected from the influences of external forces or agents (Bishop, 1960). Winter (1963) took the first steps to an explanation of why protection is so important for wound healing. Recent advances in understanding the dynamics of the wound-healing process have lead to the development of many new materials for the treatment of wounds; most of them are based on the principles of occlusion. This article describes some of the pathophysiological and quality of life advantages of occlusive dressings.
Prevention
of desiccation
of the wound bed
The importance of desiccation, which, in a wound, leads to scab formation, was demonstrated in animal experiments in which wounds were occluded or left exposed to the air. The scab that formed in the open wounds decreased the migration possibilities of keratinocytes, resulting in impaired wound healing (Winter, 1963). This general phenomenon turns out to be particularly important in partial skin thickness burns, If the zone of delayed stasis, which, in a burn wound, surrounds the central necrotic zone, is protected from desiccation, hair follicles and other remnants of the skin remain viable and form a focus from which wounds heal (Zawacki, 1974a,b). Wounds which are occluded with a material with a sufficiently low moisture vapour transmis10 1992 Butterworth-Heinemann 0305-4179/92/S2OS15-04
Ltd
sion rate (MVTR) do not dry out and this allows the tissue to retain its viability. It has been shown that conventional materials like tulle gauze have an MVTR which is too high (Jo&man, 1989). The ideal MVTR for a dressing is still an open question. Semipermeable materials (such as films) and impermeable materials (such as some hydrocolloids) all prevent desiccation of the wound (Hinman and Maibach, 1963; Alper et al. 1983; May, 1983; Hermans and Hermans, 1986), in spite of the differences in their MVTR.
Mechanical effects of a dressing wound bed
on the
Some dressings adhere to the wound bed so firmly that removing them leads to destruction of vital tissues or removal of newly grown epithelium. This impairs the wound healing process. Mechanical disturbance can regularly be observed when gauze-type materials are used. Bleeding of the wound bed and the pain during removal are both signs of mechanical damage (Winter, 1970). Sometimes tissue can even be found in the tulle (Gillman, 1970). Occlusive materials usually do not damage the wound bed upon removal because the moisture film between the dressing and the wound bed prevents firm adhesion to tissues.
(Bio)chemical wound bed
effects of a dressing
on the
Cotton-based materials can induce ‘biochemical disturbance’ to the wound: they may induce foreign-body reactions with giant cells and hyperinflammation (Gillman, ‘1970) or granulomas (Woods, 1976). Antiseptics are also known to disturb the wound healing process. Although some of these materials are only mildly cytotoxic (Ray et al., 1988), all of them do impair the tissue repair process, which results in a decrease in the rate of epithelialization (Monafo and Ayvazian, 1978; Bolton et al., 1985; Warden, 1987). Careful attention must be paid to indications for these agents; if they are not indicated they should not be used ‘as a precaution’ because they may have detrimental effects on cell growth (Cooper et al., 1991) or even cause severe systemic effects (Rath and Meissl, 1988).
Burns (1992) Supplement 2
S16
Occlusive materials usually are made out of synthetic constituents. with minor or non-existent side-effects; some of them produce a wound environment that, in itself, allows for optimal antimicrobial activity of the host defense cells (May, 1984; Varghese et al., 1988); hence, the use of local antimicrobials is quite often not necessary. pH and temperature The pH that exists in and above a wound has been shown to have an influence on tissue repair. A slightly acidic pH, as is provided by some of the occlusive materials, has mild antibacterial effects (Mertz et al., 1985; Katz et al., 1986; Mulder et al., 1989). Moreover, wounds that are exposed to air rapidly lose CO, and develop a local respiratory alkalosis which may lead to healing failure (Leveen et al., 1973). In an occlusive environment the pH can be controlled in a more secure way than in a non-occlusive environment in which exchange of gases and fluids between the wound surface and the atmosphere is possible (Leveen et al., 1973). The local temperature is somewhat higher in an occlusive environment which speeds up the healing rate of wounds (Gimbel and Farris, 1966; Leveen et al., 1973). In larger wound surfaces, occlusion may help in reducing the respiratory and metabolic effects of hypothermia (Dill and Forbes, 1941; Hemdon et al., 1987).
Infection and wound healing A literature survey has shown that the overall infection rate under occlusive dressings is lower than under conventional dressings (Hutchinson, 1989). In other studies it has been shown that Psetld. aentginasa disappears in a moist wound environment (Gillchrist and Reed, 1989) as provided by some dressings, and that wounds do heal in spite of their heavy and unchanging bacterial contamination (Gillchrist and Reed, 1988). A possible explanation for these phenomena may be found in the availability of polymorphonuclear cells (PMN): in wounds covered with an occlusive material the number of these cells is very high (Buchan et al., 1981), whereas, in the presence of a scab, the number of PMNs is decreased (Falanga, 1988). PMNs are likely to be the most important defence against infection and the ability of these cells to enter the wound site is therefore crucial. It has been shown that the activity of PMNs in fluid collected from skin lesions, treated with occlusive materials, is at least as high as that in autologous blood (Katz et al., 1986). Studies on PMNs, obtained from occluded wounds, have demonstrated the presence of stainable bacterial inclusions (May, 1983; Varghese et al., 1986): this suggests previous ingestion of bacteria. Dressings also can provide a barrier for microorganisms. A physical barrier against bacterial invasion exists in some of the occlusive dressings (Lawrence and Lilly, 1988). This helps to diminish the overall bacterial load with which the host defense mechanisms have to deal. One of the ‘side-effects’ of the viability of the PMNs and the macrophages is the autolytic debridement that occurs in an occlusive environment: this speeds up ‘preparation of the wound bed for re-epithelialization.
Quality of life Bumwounds are extremely painful and so are donor sites. When choosing treatment may sufficiently.
local wound treatments, the pain such a cause is not always taken into account
An occlusive wound environment offers excellent pain relief in many types of wounds (Donati and Vigano, 1988; Fechner and Kon, 1988; Hedman, 1988; Sayers and Porter, 1988; Waffle et al., 1988) possibly because the nerve endings are prevented from desiccation. Patient comfort is also enhanced when personal hygiene (showering, bathing) and other activities of daily living are not hampered. Some these benefits (Hermans and van dressings provide Wingerden, 1990). The long-term results of bum wound healing are very important: cosmetically unacceptable scars are still a major problem in bum care and may have a severe impact on the quality of life. Hypertrophic scarring is probably the single most important long-term cosmetic problem. Many hypotheses have been developed on the actual cause of hypertrophic scarring. Collagen deposition (Efting Dykstra, 1977) and myofibroblasts (Baur et al., 1975) are important, but to date a completely satisfactory explanation has not been found. Treatment of hypertrophic and keloid scars is even more controversial (Peacock, 1983) although the use of pressure garments or silastic sheets (Afin et al., 1989) is accepted as ways to reduce the scars. This type of therapy, which is expensive and uncomfortable for the patient, will not result in a complete disappearance of the scars. Reducing the chances of hypertrophic scar development is extremely important. One probable way of reducing the incidence of these scars is by the use of occlusive materials (Leveen et al., 1973; Tjong Wai et al., 1983; May et al., 1984; Eisenberg, 1986; Hermans and Hermans, 1986; Hoekstra, 1990).
Cost-effectiveness Many clinicians consider modem occlusive materials to be too expensive. The price per unit of occlusive dressings may be higher than those of conventional dressings, but the overall costs of treatment are not determined by the primary dressing alone. Additional costs may include fixation bandages and other miscellaneous materials such as gloves. The wearing time of a dressing influences the number of dressing changes and the nursing time involved. Healing time of a wound has a serious effect on the hospitalization time, and therefore on the overall cost of a particular treatment. For chronic lesions (leg ulcers; Harkiss, 1985) and for bums (Hermans, 1990) it has been shown that occlusive materials can be more cost effective than conventional materials. As the healing time of a wound usually is much shorter when occlusive therapy is used (Winter, 1963; May, 1984; Hermans, 1987; Donati and Vigano, 1988), cost differences probably would have been even more dramatic had hospital costs been calculated in these studies.
Indications There are many excellent classifications available for wound dressings (Guldalian et al., 1973; Queen et al., 1987) and this article is not meant to make another one. Therefore, only some indications and contraindications for occlusive materials are given below. Full skin-thickness burns A. In relatively large full skin thickness bums hardly any indication exists for the current synthetic materials. Only when excision is performed without grafting of all the excised areas, some occlusive materials may be used. These should be synthetic or biological materials that (firmly) adhere to the wound bed to provide protection
Hermans: Treatment of burns with occlusive dressings
against desiccation and contamination. All these materials are known to block re-epithelialization, however. In the sandwich (Alexander et al., 1981) or intermingled (Yang et al., 1980) techniques allografts play a crucial role; they provide coverage of the interstices and serve as a scaffold for migration of the keratinocytes from the autografts. B. Only very small full skin thickness bums (maximum 3-5 cm in diameter) may be treated without excision and grafting. Even then, healing will be slow but, often, satisfactory (Hermans and Hermans, 1988). Partial skin thickness
burns
A. Most of these bums are not life threatening because they are fairly small. The primary aim in the treatment of these bums is to restore cosmetically good skin. It is here that the use of occlusive dressings, whether biological or (semi) synthetic, is most indicated. 1. Biological materials, such as allografts, amnion, and, to a lesser extent, xenografts, have the advantage of adhering to the wound bed and, in most cases, they remain adherent until the wound underneath is healed. They block the formation of exudate. The materials may transfer diseases from the donor to the acceptor. In particular the allografts are capable of transferring viral diseases such as hepatitis and AIDS, although some preservation methods seem to be able to inactivate viruses and kill bacteria (Hoekstra et al., 1990). Rejection of biological dressings may be a problem and storage and availability is relatively complicated. Cosmetically, excellent results have been described (Tjong Wai et al., 1983; Eisenberg, 1986). Less common biological materials for the treatment of partial skin thickness bums are hen-egg membranes, banana leaves, potato peels, and multiple collagen films. With all of them good results have been described. Z. (Semi)synthetic materials. The number of (semi)synthetic
dressings has grown extensively during recent years. Theoretically, most materials offer a wound environment which is beneficial to the local wound healing process. Clinically there are major differences in performance of the materials, even within subgroups that are claimed to have similar properties. For many occlusive dressings pain relief is claimed to be good (Donati and Vigano, 1988; Fechner and Kon, 1988; Hedman, 1988; Sayers and Porter, 1988; Waffle et al., 1988), as are the speed of re-epithelialization and patient comfort. They
are readily
available
and easy to store.
The main advantage of synthetic over biological dressings is their ease of use: not much specific knowledge is required. Donor
sites
Most donor sites are very painful, but they do not cause healing problems. For most occlusive dressings clinical trials have been done with donor sites, and most of them with excellent results (Madden et al., 1985; Donati and Vigano, 1988; Fechner and Kon, 1988). Practical problems may occur for donor sites that are surrounded by grafted or burned areas; those occlusive dressings that require normal skin around the wound to adhere to cannot be used. Donor site treatment may then interfere with the other local treatment regimens.
s17
Conclusion In recent years, evidence that managing wounds with occlusive dressings offers many advantages has grown substantially. Although the treatment of full skin thickness bums has not yet acquired much from this evidence, it has been shown that partial skin thickness bums, which form the majority of all bum cases, really can gain from the use of occlusive dressings, because these materials provide fast re-epithelialization with low incidence of infection and good cosmetic results. In addition to the medical benefits observed, patient quality of life is increased and treatment costs reduced. It should be realized, however, that not all occlusive materials, not even all materials in one subgroup, share the same properties; this may result in clinically different properties (Lawrence and Lilly, 1988). It is therefore very important to only use materials that have been clinically tested for a particular indication (Bolton and Rijswijk, 1991).
References AhnS. T., Monafo W. W. and
Mustoe T. (1989) Topical silicone gel: a new treatment for hypertrophic scars. Surgery 10, 781. Alexander J. W., MacMillan B. G., Law E. et al. (1981) Treatment of severe bums with widely meshed skin autograft and meshed skin allograft overlay. 1. Trauma 21, 433. Alper J. C., Welch E. A., Ginsberg M. et al. (1983) Moist healing under a vapour permeable membrane.]. Am. Acad. Dem. 8,347. Anonymous (1700 Bc) Papyrtrs Smith Papers. Baur P. S., Lason D. L. and Stacey T. R. (1975) The observation of myofibroblasts in hypertrophic scars. Surg. Gynecol. Obstef. 141, 22. Bishop W. J. (1960) Be Early Hisfory of Surgery. Worcester and London: Ebenezer Baylis and Sons Ltd, The Trinity Press. Bolton L. and van Rijswijk L. (1991) Wound dressings: meeting clinical and biological needs. Dermatol. Nut-s. 4, 146. Bolton L., Oleniacz W., Constantine B. et al. (1985) Repair and antibacterial effects of topical antiseptic agents. In: Maibach H. and Lowe N. (eds), Models in Dermatology. Karger, BaseI: Maibach and Lowe, p. 145. Buchan I. A., Andrews J. K., Lang S. M. et al. (1981) Clinical and laboratory investigation of the composition and properties of human skin wound exudate under semi permeable dressings. Burns 7,326. Chardack W. M., Brueske D/A., Santomauro A. P. et al. (1962) Experimental studies on synthetic substitutes for skin and their use in the treatment of bums. Ann. Swg. 155, 1.27. Cooper M. L., Laxer J. A. and Hansbrough J. (1991) The cytotoxic effect of commonly used topical antimicrobial agents on human fibroblasts and keratinocytes. 1. Truumn 31, 775. Dill D. B. and Forbes W. H. (1941) Respiratory and metabolic effects of hypothermia. Am. J Physiol. 132, 685. Donati L. and Vigano M. (1988) Use of the hydrocolloidal dressing DuoDERM for skin donor sites for bums. hf. 1. Tissue Reacfions 4, 267. Efting Dykstra J. D. (1977) Littekenvonning. Thesis, Meppel, Netherlands: Krips Repro. Eisenberg M. (1986) The effect of occlusive dressings on reepithelialization of wounds in children with epidermiolysis bullosa. I. Pediafr. Surg. 21, 892. Falanga V. (1988) Occlusive wound dressings. Arch. Dematol. 124,872.
SlS Fechner M. R. and Kon M. (1988) De behandeling van donorplaatsen van huidtransplantaten met polyvinylhydrogelfolie. Ned. Tijdschr. Geneeskd. 25,1174. Gillchrist B. and Reed C. (1988) The bacteriology of leg ulcers under hydrocolloid dressings. In: Ryan T. J. (ed.), Beyond Occlusion, Woundcare Proceedings. R. Sot. Med. 136,83. Gillchrist B. and Reed C. (1989) The bacteriology of chronic venous ulcers treated with occlusive hydrocolloid dressings. Br. 1. Dermatol. 4, 337. Gillman T. (1970) Outline of some aspects of the healing of full thickness loss excised wounds. In: Had&s K. J. (ed.), Surgical Dressings and Wound Healing. Bradford: University Press, p. 98. Gimbel N. S. and Farris W. (1966) The influence of surface temperature in the epithelialisation rate of split thickness donorsites. Arch. Surg. 92, 554. Guldalian J., Jelenko C., Callaway D. et al. (1973) A comparative study of synthetic and biological materials for wound dressings. 1. Traum 13,32. Harkiss K. (1985) Cheaper in the long run. Community O&look
124,872. Hedman L. A. (1988) Effect of a hydrocolloid dressing on the pain level from abrasions on the feet during intensive marching. Milit. Med. 153, 188. Hermans M. H. E. (1987) Hydrocolloid dressing (DuoDerm) for the treatment of superficial and deep partial thickness bums. Stand. 1. Plast. Reconstr. Surg. 21,283. Hermans M. H. E. (1990) The role of hydrocolloid dressings in modem wound care. Trauma 1. Accid. Emerg. Med. 6, 12. Hermans M. H. E. and Hermans R. I’. (1986) DuoDerm, an alternative for the treatment of smaller burns. Burns 12,214. Hermans M. H. E. and van Wingerden S. (1990) Treatment of industrial wounds with DuoDERM bordered: a report on medical and patient comfort aspects. 1. Sot. Occq Med. 40, 3. Treatment of Herndon D. N., Curreri I’. W., Abston S. et al. (1987) bums. In: Ravitch M. M. (ed.), Currenl Problems in Surgery. Medical Publishers, p. 347 Hinman C. D. and Maibach H. (1963) Effect of air exposure and occlusion on experimental human skin wounds. Nature 200, 377. Hoekstra M. J. (1990) Specisle behandelingen van brandwonden. In: Hermans M. H. E. (ed.), DuoDERM Symposium Proceedings. Amsterdam: Excerpta Medica, p. 111. Hoekstra M. J., Buttenwerf J., Kreis R. W. et al. (1990) Cadaverskin and viruses. Proceedings of the 8th International Congress on Bum Injuries, New Delhi, India, p. 179. Hutchinson J. J. (1989) Prevalence of wound infection under occlusive dressing: a collective survey of reported research. Wounds 1, 123. Jo&man M. F. (1989) Epiderrnal Wound Healing betzoeen Moist and Dy Dressing. (Thesis). Groningen: Groningen University Press. Katz S., McGinley K. and Leydon J. J. (1986) Semipermeable occlusive dressing. Effect on growth of pathogenic bacteria and reepithelialisation of superficial wounds. Arch. Dermatol. 122,
58. Lawrence J. C. and Lilly H. A. (1988) Bacterial barrier properties of hydrocolloid dressing in vitro. In: Ryan T. J. (ed.), Beyond Occlusion, Wound Care Proceedings. R. Sot. Med. 136,75. Leveen H. H., Falk G., Borek B. et al: (1973) Chemical acidification of wound: an adjuvant to healing and the unfavourable action of alkalinity and ammonia. Ann. Surg. 138, 745. Madden M. R., Finkelstein J. L., Hefton J. M. et al. (1985) Optimal healing of donor sites with hydrocolloid dressings. In: Ryan T. J. (ed.), An Environmenl for Healing. R. Sot. Med. 136,133.
Bums(1992)Supplement2 May S. R. (1983) Physiological activity from an occlusive wound dressing. In: Lawrence J. C. (ed.), Wound Healing Symposium. Oxford: Medical Publishing Foundation, p. 35. May S. R. (1984) Physiology, immunology and clinical efficacy of an adherent polyurethane dressing: Opsite. In: Wise L. W. (ed.), Burn Wound Coverings, vol. II. Boca Raton, FL: CRC Press, p. 53. Mertz P. M., Marshall D. and Eaglstein W. H. (1985) Occlusive wound dressing to prevent bacterial invasion and wound infection. J. Am. Acad. Dematol. 12,662. Monafo W. W. and Ayvazian V. H. (1978) Topical therapy. Surg. Clin. North Am. 6, 1157. Mulder G. D, Kissil M. T. and Mahr J. J. (1989) Bacterial growth under occlusive and non-occlusive wound dressing. Wounds 1, 63. Peacock E. E. Jr (1983) Pharmacological control of surface scarring in human beings. Ann. Surg. 193,592. Pickerel1 K. L. (1942) A sulphonamide film for use as a surgical dressing. Bull. ]ohn Hopkins Hosp. 71, 304. Bums wound Queen D., Evans J. H., Gaylor J. D. S. et al. (1987) dressings - a review. Burns 13,218. Rath Th. and Meissl G. (1988) Induction of hyperthyroidism in bum patients treated with povidone-iodine. Burns14,320. Ray M., San J. and Antonys G. L. (1988) Tolerance and therapeutic efficacy of topically applied SSD cream in infected wounds. Curr. 7’her. Res. 43,1025. Sayers R. and Porter K. M. (1988) Comparison of DuoDERM and medicated tulle-gras in the treatment of fingertip-injuries. In: Ryan T. J. (ed.), Beyond Occlusion, Woundcare Proceedings. R. Sot. Med. 136,133. Tjong Wai R., Kreis R. W. and Hermans R. P. (1983) Resultaten van de behandeling met allogene huidtransplantaten van verbranding door hete vloeistoffen bijn kinderen. Ned. Tijdschr. Geneesk. 290. Varghese M. C., Balin A. K., Carter D. M. et al. (1986) Local environment of chronic wounds under synthetic dressings. Arch. Dermatol. 122,52. Waffle C., Simon R. R. and Jo&n C. (1988) Moisture vapour permeable film as an outpatient bum dressing. Burns 14,66. Wallace A. B. (1941) The Treatment of Burns. Oxford War Manuals. London: Humphrey Milford. Warden G. D. (1987) Outpatient management of thermal injuries. Bull. Burn lnj. 30. Wichterie 0. and Lim D. (1962) Hydrophilic gels for biological use. Nature 185, 117. Winter G. D. (1963) Effect of air drying and dressings on the surface of a wound. Nature 197,91. Winter G. D. (1970) Healing of skin wounds and the influence of dressings in the repair process. In: Harkiss K. J. (ed.), Surgical Dressings and Wotind Healing. Bradford: Bradford University Press, pp. 46-51. Wong P. (1980) Physical evaluation of hydrogel as a bum wound dressing. M.Sc. Thesis, University of Strathclyde. Woods R. A. B. (1976) Disintegration of cellulose dressings in open granulating wounds. Br. Med. J 1444. Yang C. C., Shih T. S., Chu T. A. et al. (1980) The intermingled transplantation of auto and homografts in severe bums. Burns 6,
141. Zawacki B. E. (1974a) The natural history of reversible burn injury. Surg. Gynecol. Obstet. 139,867. Zawacki B. E. (1974b) Reversal of capillary stasis and prevention of necrosis in burns. Ann. Surg. 139,98. Correspondence should be addressed lo: Dr M. H. E. Hermans, Director Medical Development, ConvaTec International, 200 Headquarters, Park Drive, Skillman, NJ 08558, USA.
