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MOIST WOUND HEALING AND MOIST EXPOSED
THERAPY
Professor Bishara S. Atiyeh and Dr Shady N. Hayek
American University of Beirut Medical Center, Beirut, Lebanon
Introduction
Wound healing is a complex and highly regulated process that can be compromized
by both endogenous and exogenous factors.1 In both
primary and secondary healing it consists of a series of events characterized
by inflammation, epithelialization, connective tissue deposition and contraction.
The contribution of each event varies according to the type of wound.2
At any rate, the longer it takes for spontaneous wound healing to be completed,
the worse the outcome usually is, with increasing likelihood of developing
hypertrophic scarring and unsightly alterations in pigmentation. Moreover,
under unfavorable conditions, the self-perpetuating inflammatory cascade
may result in increasing tissue destruction and necrosis rather than healing.3,4
On the other hand, understanding the concept of occlusion has been fundamental
to the evolution of our knowledge about wound healing leading to the development
of new wound dressings and has created a paradigm shift in the management
of wounds.6,7,8,9,10 Before this understanding,
wounds often were kept dry, as advocated by Pasteur to keep them ‘germfree‘.6
There is now growing evidence of improved healing of full- and partial-thickness
cutaneous wounds in wet and moist environments. Retention of biologic
fluids over the wound prevents desiccation of denuded dermis or deeper
tissues and allows faster and unimpeded migration of keratinocytes over
the wound surface. It allows also the naturally occurring cytokines and
growth factors to exert their beneficial effect on wound contracture and
re-epithelialization. Enthusiasm generated by these results has been,
however, tempered by concerns over tissue maceration and infection following
prolonged cutaneous water exposure.2,11 These concerns
may not be justified.2,12,13 Nevertheless, despite
mounting evidence and appreciation of the biologic beneficial factors
of moist environments, applying the moist healing principles to large
surface areas, in particular to large burns and skin graft donor sites,
is hindered by the major impracticality and technical handicap of creating
and maintaining a sealed moist environment over these areas.5,14,15
Dressings have been used since antiquity to facilitate the healing process.
More recently many sophisticated dressings have become available to the
wound care practitioner. These newer materials and agents supplement older
dressing materials, such as gauze, which still are commonly used.6
Wound dressings provide several important functions including protection,
prevention of infection, promotion of healing through keeping the wound
moist and warm, reduction of pain, absorption of exudate, comfort, stability
and reduction of wound motion. Dressings should also be easy to apply
and remove without causing further trauma. Although there is not one ideal
dressing capable of providing all these functions, and not every wound
requires every attribute, yet a wound may need a different dressing as
it progresses through the healing process.6,7,8
Different dressing materials, devices and agents provide different functions
to greater or lesser degrees, and the attributes of each need to be matched
to the specific wound on which it is placed.6
Moist Exposed Burn Ointment
Since recent evidence suggests that moist environment favors more optimal
healing, and since currently available moisture retentive devices cannot
be universally applied, clinical trials were conducted to evaluate the
efficacy of a newly introduced moisture retentive ointment, MEBO (Moist
Exposed Burn Ointment) (Julphar Gulf Pharmaceutical Industries, UAE),
on primary healing of surgically repaired wounds and on re-epithelialization
of partial thickness wounds. The ointment is capable of providing an optimal
moist environment without the need of an overlying occlusive dressing.
MEBO is a Chinese burn ointment with a USA patented formulation since
1995. The active component of the ointment is b-sitosterol in a base of
beeswax, sesame oil and other components. Clinical and experimental studies
reported in the Chinese literature have demonstrated that it reduces markedly
evaporation from the wound surface.15 Though MEBO
does not have any demonstrable in vitro bacteriostatic and bactericidal
activity probably due to its oily composition that does not allow proper
diffusion in a watery culture medium,16,17, 26,27
it has been shown that in vivo, it had similar action to 1% Silver Sulfadiazine
in controlling burn wound sepsis and systemic infection with P. aeroginosa.18,28
It has also been demonstrated experimentally that MEBO exhibited a statistically
significant wound healing potential on rabbit corneal epithelium as compared
to saline, homologous serum, Vitamin A and dexamethasone.19
The ointment produces good analgesia and has a good debriding effect,
moreover, it drastically reduces water loss and exudation from the open
wound surface. The required frequent application of the ointment is easy
and can be performed by the patient himself or a member of his family.
The most remarkable practical advantage of MEBO over other types of dressings
is that it provides an effective wet environment favorable for optimal
wound healing without the need of any covering or occlusive dressing.
In some cases, however, particularly when the patient is not confined
in bed or at home, a simple covering dressing may be more convenient.
Moist exposed burn ointment (MEBO) has been used traditionally in China
for topical burn injuries treatment and was explored by Xu Rongxiang20
from the Beijing Chinese Burn Center. It has been popularized outside
China only two and a half decades ago. Reports about its properties and
functions have been published in the Chinese literature; there was, however,
a need to independently document the claimed benefits of this ointment
in wound healing. Chinese traditional medicine (CTM) is quite different
from the type of medicine and approach to disease as practiced in the
west. Amongst our frenetic drive to develop more and more sophisticated
and active wound healing devices and treatment modalities, it is wrong,
however, to totally disregard CTM and its empirically time proven practices
and remedies. It is difficult though to accept CTM without somehow adapting
it to our ways of scientific analysis and documentation.21
Figure I: (A) Healed STSG donor site at 2.5 months.
Note better cosmetic result of the area treated with moist exposed burn
ointment (MEBO®).
Note also epidermal sliding present in the area treated by Sofra-Tulle
®.
Demarcation zone between the two treatment areas indicated by arrow.
(B and C) STSG donor sites treated by MEBO® and Tegaderm®.
Better healing with better cosmetic result observed with MEBO®.
Clinical Trials
We as well as others have already validated the claim that the ointment
effectively preserves moisture at the surface of partial thickness wounds
by both experimental studies and clinical trials. Results have already
been published documenting better re-epithelialization.21,22,23,24,25,26,27,28
When compared to the classical split thickness skin graft donor
site dressing consisting of an antibiotic impregnated Vaseline gauze (Sofra
Tulle®, Roussel Laboratories Ltd., Uxbridge, England) covered by a
bulky gauze dressing, moist exposed burn ointment promoted speedy healing
with excellent cosmetic outcome.23,24,25 Re-epithelialization
of donor sites with ointment application was also better than dressing
the donor sites with Tegaderm® (3M Health Care, St Paul, MN), a moisture
retaining semi-permeable adhesive film27,28 (Figure
1). MEBO treatment resulted in earlier anatomical healing with significantly
superior cosmetic appearance of the resultant scars over six months follow-up.
The study demonstrated also significantly faster functional healing with
restoration of cutaneous barrier function with ointment application. The
observed positive correlation between improved scar quality and early
physiologic recovery indicated that better cosmesis and improved function
are closely linked.
When evaluating primary healing using the visual analogue scale,29
cosmetically better scars consistent with lower scores are observed following
prophylactic MEBO application for a period of six weeks after wound primary
suturing at one, three, and six months when compared to a control no treatment
group and another group treated with topical antibiotic application (Fucidin®,
Leo Pharmaceutical, Danmark)30,31 (Figure 2). Though
significant differences in scores for colour, contour, distortion, and
aspect between the three groups were observed with more favorable scores
for the MEBO treated group, only colour scores exhibited significant changes
over time. At six months, the observed colour difference among the three
groups becomes nonsignificant. It is, however, extremely significant at
one and three months indicating that the permanent scar colour may be
expected at an earlier stage whenever the scar is managed prophylactically
with MEBO. Of all the parameters, only differences in texture values reflecting
deeper dermal healing became extremely significant at six months while
these were less significant at one and three months, indicating a net
divergence in fibroblastic and scar remodeling activity between the treatment
groups in favor of moist exposed burn ointment.
Figure 2: Improved scar quality of primarily
healed facial lacerations.
Conclusion
Our investigation of this new moisture retentive ointment indicates so
far that it has a definite positive effect on wound healing. The nature
of the studies and their limited clinical scope, allow us, however, only
to speculate on its mechanism of action as well as on its effect on the
various phases and components of the wound healing cascade. Further research
is still required to explore the bio-cellular mechanisms involved and
its action on the different cytokines and metalloproteinases proven lately
to be essential in determining the final outcome of healing. These reported
studies as well as another prospective clinical trial of this ointment
in topical treatment of chronic ulcers32,33 have
demonstrated the extreme ease of application and practicality of this
ointment in providing the necessary moist conditions for optimal healing
as compared to currently available labor intensive and time consuming
moisture retaining products and devices. Though it is not an antibiotic
and definitely not suitable for the treatment of established wound sepsis,
adequate local antibacterial action of the ointment maintaining open wounds
in a healthy ‘none infected’ condition has also been demonstrated.
Even when used for prolonged periods of time, emergence of resistant strains
was not observed.32,33
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Bishara S. Atiyeh, MD, FACS
Clinical Professor
Division Plastic and Reconstructive Surgery
American University of Beirut Medical Center
Beirut, LEBANON
Shady N. Hayek, MD
Chief Resident
Division Plastic and Reconstructive Surgery
American University of Beirut Medical Center
Beirut, LEBANON
Responsible Author and Reprint Requests:
Bishara S. Atiyeh, MD, FACS.
Clinical Professor
Division of Plastic and Reconstructive Surgery
American University of Beirut
Beirut, Lebanon
Tel: (916) 3 340032
Fax: (961) 1 363291
E-mail: aata@terra.net.lb
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