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The effect of topical hyperalimentation on wound healing rate and granulation tissue formation of experimental deep second degree burns in guinea-pigs
Burns (1984).
10, 252-256
Printedin Great
Britain
The effect of topical hyperalimentation on wound healing rate and granulation tissue formation of experimental deep second degree burns in guinea-pigs Theodor Kaufman, Moisey Levin and Dennis J. Hurwitz Department of Surgery (Plastic), University of Pittsburgh School of Medicine Summary
Revital, a product containing 19 amino acids, was applied to experimental deep second degree bums in guinea-pigs for 24 days, in order to assess the effect of this form of hyperalimentation on the healing process. Silver sulphadiazine cream served as the contralateral control standard. Epithelialization was faster in the silver sulphadiazine treated burn wounds, while contraction of both tested wounds proceeded at a similar rate. Revital significantly enhanced the formation of granulation and scar tissue in this burn wound model. These observations indicate that topical wound hyperalimentation promotes granulation tissue formation of experimental deep
second degree burns in guinea-pigs. INTRODUCTION
THE deep burn wound is characterized by poor vascularity and low oxygen tension which cause nutritional deprivation. Viljanto et al. (1976) observed that burns covered by sponge sheets saturated with amino acids solution, carbohydrate and vitamins significantly increased the underlying granulation tissue formation. Niinikoski et al. (1977) indicated that in a dead-space wound model in rats, local hyperalimentation with amino acids, vitamins and electrolytes enhanced collagen synthesis and DNA content. Silvetti (1981) also demonstrated that local hyperalimentation applied to full-thickness thermal burns as well as to chronic open wounds, resulted in a relative early formation of highly tissue. vascularized granulation Recently, Bergman et al. (1983), showed that honey-treated open wounds in mice promoted wound healing.
The present study was undertaken to investigate the effect of Rev&al, a product composed of 19 amino acids, on the healing rate, contraction and granulation tissue formation of experimental deep ,second-degree bums in guinea-pigs. MATERIALS AND METHODS Animals
Eight Hartley derived female guinea-pigs, weighing 350-4OOg were studied. They were kept in individual cages and fed regular chow and water ad libitwn. Burn wound model
Twenty-four hours before burning, the animal’s back was clipped and depilated under light anaesthesia (i.p. sodium pentobarbital, 15 mg/kg). Two uniform burns were inflicted (after i.p. injection of sodium pentobarbital, 35 mg/kg) symmetrically on the back of the animals, using aluminium templates measuring 3.5 x 3.5cm, heated in a 75 “C water bath for 1 hour, and applied for 8 s to the moistened skin. Preliminary studies in our laboratories employing intra-aortic India ink injection demonstrated that this wound consists of a deep second-degree burn and confirming a similar burn model (Fang et al., 1982) The actual size of the burn wound was about 17cm2 due to contraction of the panniculus camosus muscle during the bum injury which involved about 4 per cent of the total body surface area.
Kaufmanet al.: Topical hyperalimentation
Revital Revital (Robertson Resources Ltd, Salisbury, MD, USA) is a mixture of 19 amino-acids (Table I) extracted from immature chicken feet. In the powder form which was employed in the present study, Revital has a pH of 4.6 when dissolved in water, a total water and nitrogen content of 7.9 and 1573 g per cent respectively and 6.10 g per cent of ash. The powder is hygroscopic, attracts water and moisture from the burn wound surface, and tends to be ‘muddy’ adhering to the wound. The agent is removed by saline irrigation. Tab/e I. Amino acid composition of Revital (mg per cent) Aspartic acid Glutamic acid Histidine Lysine Hydroxylysine Proline Hydroxyproline Arginine Threonine Serine
5.51 IO.24 0.81 3.80 I.19 11.83 IO.14 8.01 2.26 2.86
Tyrosine Glycine Cvstine Aianine Phenylalanine Methionine Leucine lsoleucine Valine
0.73 23.41 0.73 9.14 2.23 1 ,24 3.00 1.76 2.43
Mode of treatment Revital was applied to the right burn wound injury in the amount of 3 g per 17.76crn’ of burn area and changed every three days. To the contralateral control burn wound, Silvadene (1 per cent silver sulphadiazine cream, Marion Lab. Inc., Kansas City, MI, USA) was applied at a similar dose and dressings were changed every 3 days. Both wounds on each animal were separately dressed with a non-adhesive sterile Telfa dressing, (Kendall Company, Boston, MA, USA). Assessment of wound healing Evaluation of the open wound area, as well as that enclosed by the normal, hair bearing skin, was carried out employing the macrophotography technique (Kaufman et al., 1982) Areas were measured with a compensating polar-planimeter. The healing rate was monitored every 3 days for a total period of 24 days. Wound epithelialization as a per cent of the original wound size, was calculated employing the following formula: E=_-
A,-&
x 100,
4 where E = rate of epithelialization A, = area enclosed by the normal,
in per cent; hair bearing
skin on a given post burn day; A, = area of open wound on the same day as was measured. Wound contraction was calculated using the following formula:
c=- A, ---Anx 100. where C = rate of burn wound contraction expressed in per cent; A, = burn area as measured immediately following the burn injury; A, = area enclosed by normal, hair bearing skin. Morphology The animals were sacrificed on post-burn day (PBD) 24, and four punch biopsies (2mm in diameter) were taken from representative and comparable mirror image areas from the treated and control burn wound scars in each animal. Assessment of scar and epidermal thickness and volume Since collagen synthesis evaluation in resurfacing bum wound models is unreliable (Kaufman, 1982, unpublished data), measurements of the thickness of the newly formed scar tissue and its volume as well as that of the epidermal layer were carried out instead. Quantitation of the granulation and scar formation employing this approach provides an accurate estimation of the total amount of the newly formed scar tissue composed of newly deposited collagen as well as the cell-producing collagen population. Three segments of the scar tissue with their corresponding epidermal layers have been measured by means of an eyepiece micrometer in two adjacent sections from the centre of each punch biopsy. The volumes of the scar and epidermal layers were calculated by multiplying their thickness by the size of the wound on PBD 24. Analysis of data The analysis of variance was employed to assess the difference in the rate of epithelialization and contraction of the Revital and Silvadene treated wounds. The Student’s t test was used to evaluate the difference in wound healing on PBD 24 as well as for the difference of tissue thickness. RESULTS The mean burn size fs.e.m. of the Revital and Silvadene treated wounds following the burn injury were 17.76 + 1.34cm2 and 17.76kO.93 cm2, respectively. The mean per cent of healing rate +s.e.m. of the Revital-treated burns on PBD 9, 15, 18 and 24 were 41.78k1.35; 73.97k2.71;
254
BurnsVol. 1 O/No. 4
83*19+_3.24 and 94.34 + 1.81 respectively, and that of the Silvadene-treated wounds were 51.75 + 1.56; 86.96 + 2.61; 99.05 kO.94 and 100 respectively (Table II). The Silvadene-treated burns healed faster than the Revital-treated wounds (P ~0.005). The contraction rate on both tested burn wounds was similar (Table ZZZ)except on PBD 12 in which the Silvadene-treated bums contracted significantly more than the Revital treated wounds (P < 0.05). Table II. The rate of epithelialization (per cent) PBD
Silvadene
Revital
9 12 15 18 21 24
51.75i1.56’ 73.80*1.30’ 86.96h2.61 t 99.05*0.94t 1oo.oot 1oo.oot
41.78&l ,35 57.24i1.89 73.97*2.71 83.19k3.24 89.49*3.03 94.34il.81
‘P
t/J
Table Ill. The rate of contraction (per cent) PBD 6 9 12 15 :: 24 ??
Silvadene 80.91*3.88’ 68.73*3.26t 54.52*2.21$ 47.92*2,95t 42.35*3.01 35.79i3.47’ 23.70*3.75=
No significance; tP
Revital
??
83.62i3.07 61.74i2.84 45.4oi1.90 40.87k3.13 36.99i3.32 31.31*3.88 21.05i2.96
SPiO~O5.
There were 192 measured thicknesses of the newly formed scar tissue and epidermis in each test group of bum wounds. The Revital-treated bums consistently had a thicker scar than the Silvadene-treated wounds. The mean thickness of the newly formed scar tissue +s.e.m. on PBD 24 for the Revital and Silvadene-treated bums was 0.558 kO.103 mm and 0.288 &O.l38mm, re-
spectively (P
The healing process of our burn wound model consisted of epithelialization, contraction and formation of granulation and scar tissue. The epithelialization rate of the Silvadenetreated bums was significantly faster than the Revital-treated wounds. We assume that the hygroscopic effect of Revital delayed to some extent the mitosis and migration of the epidermal cells in this bum wound model. On the other hand, the moisture provided by the Silvadene to the control bums promoted epithelialization. Contraction of the wounds proceeded at a similar rate in both test groups, except on postburn day 12, in which the Sil.vadene-treated burns contracted more than the Revital wounds. We attribute this observation &‘some methodological error and speculate that both agents did not differ in their effect or lack of effect on the contraction rate of this burn wound model. Clinical studies suggested that topical hyperalimentation promoted the formation of a well vascularized granulation tissue of deep burns (Viljanto et al., 1976; Silvetti, 1981). In a controlled study, Niinikoski et al. (1977) has indicated that local hyperalimentation with amino acids, electrolytes and vitamins, significantly enhanced fiydroxyproline synthesis as well as the total number of cells in the newly formed granulation tissue, as reflected by the increased amount of DNA. In this study the investigators contrived a wound model in which granulation tissue grew into a subcutaneously implanted sponge in rats. Our burn wound model is also an injury deprived of nutritional substances and tissue oxygen due to ischaemia.
Table IV. Quantitative assessment of scar tissue and epidermal formation on PBD 24 Granulation tissue Volume Thickness (cm’) (mm) Revital Silvadene
0.558+0,103t 0.288*0.138
* No significance; tPcO.001.
0.099t 0.051
Epidermis Thickness Volume (cm3) (mm) 0.156*0.009* 0~145*0~012
0.027 0.025
255
Kaufmanet al.: Topical hyperalimentation
Since accurate quantification of collagen synthesis is not available to us, we measured the thickness and volume of the newly formed scar and granulation tissue. The Revital-treated burns exhibited a 1.9-fold thicker scar than the Silvadene-treated control wounds. Clinically this situation is undesirable. Our observations support the findings of others (Silvetti, 1981; Viljanto et al., 1976). We do not know why Revital caused an increase of granulation and scar formation in our burn wound model. Perhaps, it was due to chemical irritation of the burn wound as Revital has a pH of 4.6. It has been shown that acidification of wounds promoted healing and significantly increased the PO, of wound surface ‘by virtue of an appropriate shift in the oxyhaemoglobin-haemoglobin dissociation curve’ (Leveen et al., 1973). Increased availability of oxygen might increase the levels of pH in the wound as well as that of the intracellular compartment due to enhancement of the aerobic metabolism. Moreover, it has been suggested that a rise of the intracellular pH might serve as a signal for certain cells to divide and increase DNA and protein synthesis (Marx, 198 l), possibly through the production of a growth factor that stimulates a subset of the cell population to divide. We speculate, therefore, that the Revital’s low pH contributed to the formation of a thicker layer and volume of scar tissue. Perhaps, the hygroscopic effect of Revital might have significantly decreased the oedema in the burn tissue and hence, blood flow through the capillary bed was less affected by the thermal
injury sequelae than the Silvadene-treated burns. Therefore, the wound might reach higher PO2 tensions and hence, stimulate collagen synthesis. In fact, other investigators added to the amino acid mixtures some agents which possibly reacted as hygroscopic agents (Silvetti, 1981; Bergman et al., 1983). The multiple variables employed concurrently in the reported studies, should be carefully considered in order to accept the concept that topical hyperalimentation promotes healing and granulation tissue formation. The variables are listed in Table V. Niinikoski et al. (1977) postulated that local hyperalimentation promotes the number of collagen production cells as well as collagen synthesis. Using a similar mixture of amino acids, electrolytes, glucose and vitamins, Viljanto et al. (1976) suggested that tissue levels of adenosine triphosphatase were increased. None of the studies has proved that the nutrients topically applied were really incorporated by the granulation tissue cells. Therefore, one can assume that the effects of local hyperalimentation on wound healing and granulation and scar tissue formation could be attributed to some non-specific stimulations to the underlying connective tissue, possibly mediated by pH, hypertonicity and hygroscopy of the nutrient agent or by local mechanical factors. REFERENCES Bergman A., Yanai J., Weiss J. et al. (1983) Acceleration of wound healing by topical application of honey. An animal model. Am. J. Surg. 145, 374.
Tab/e V. Summary of the variables employed in different studies Vioanto (1976)
Niinikoski (1977)
Wound model
Open wounds, burns
Species Variables
Patients Salt sol.. vitam.,A.A. sol. sponges topically Unknown Unknown Unknown
Subcutaneous implanted sponges Rats Salt sol., vit., A.A. sol., sponges with dead space Unknown Unknown Unknown
PH Osmolarity Hygroscopic Results Closure wound Granul. tissue Other
ttt ATPase ttt
Hydroxyproline Ttt DNA tTT
(1981)
Bergman (1983)
Kaufman (7983)
Ch. open wounds, burns
Open wounds
Burns
Patients Salt & A.A. sol., D-glucose polysaccharide powder, vitamin C. 6.5 Unknown Possible
Mice
Guinea-pigs Amino-acid powder
m m
honey
3.6 Hypertonic Very potent
4.6 _ Potent
Delayed ttt
256 Fang C. H., Alexander J. W. and MacMillan B. G. (1982) Beneficial effects’of Hydron burn dressing on scar contraction and wound healing following deep partial-thickness bum injury. J.B.C.R. 3, 164. Kaufman T., Berlatzky Y. and Alexander J. W. (1982) The microclimate chamber for evaluation of the burn size and the rate of burn wound healing by serial photomacrography. Plast. Reconstr Surg. IO, 641. Leveen H. H., Falk G., Borer B. et al. (1973) Chemical acidification of wounds, an adjuvant to healing and the unfavorable action of alkalinity and ammonia. Ann. Surg. 178, 745. Marx J. N. (1981) Investigators focus on intracellular pH. Science 213, 745.
Burns Vol. 1 O/No. 4
Niinikoski J., Kivisaari J. and Viljanto J. (1977) Local hyperalimentation of experimental granulation tissue. Acta Chir. Stand. 143, 2OF.
Silvetti A. N. (1981) An effective method of treating long-enduring wounds and ulcers by topical application of solutions of nutrients. J. Dermatol. Surg. Oncol. 7, 501. Viljanto J. and Raekallio J. (1976) Local hyperalimentation of open wounds. Br. J. Surg. 63, 427.
Paper accepted 13 October 1983.
Correspondence shouldbe addressed fo: T. Kaufman MD, Department of Surgery (Plastic), University of Pittsburgh School of Medicine, The Monte&are Hospital, 3459 Fifth Avenue, Pittsburgh, Pennsylvania 15213 USA.
10, 252-256
Printedin Great
Britain
The effect of topical hyperalimentation on wound healing rate and granulation tissue formation of experimental deep second degree burns in guinea-pigs Theodor Kaufman, Moisey Levin and Dennis J. Hurwitz Department of Surgery (Plastic), University of Pittsburgh School of Medicine Summary
Revital, a product containing 19 amino acids, was applied to experimental deep second degree bums in guinea-pigs for 24 days, in order to assess the effect of this form of hyperalimentation on the healing process. Silver sulphadiazine cream served as the contralateral control standard. Epithelialization was faster in the silver sulphadiazine treated burn wounds, while contraction of both tested wounds proceeded at a similar rate. Revital significantly enhanced the formation of granulation and scar tissue in this burn wound model. These observations indicate that topical wound hyperalimentation promotes granulation tissue formation of experimental deep
second degree burns in guinea-pigs. INTRODUCTION
THE deep burn wound is characterized by poor vascularity and low oxygen tension which cause nutritional deprivation. Viljanto et al. (1976) observed that burns covered by sponge sheets saturated with amino acids solution, carbohydrate and vitamins significantly increased the underlying granulation tissue formation. Niinikoski et al. (1977) indicated that in a dead-space wound model in rats, local hyperalimentation with amino acids, vitamins and electrolytes enhanced collagen synthesis and DNA content. Silvetti (1981) also demonstrated that local hyperalimentation applied to full-thickness thermal burns as well as to chronic open wounds, resulted in a relative early formation of highly tissue. vascularized granulation Recently, Bergman et al. (1983), showed that honey-treated open wounds in mice promoted wound healing.
The present study was undertaken to investigate the effect of Rev&al, a product composed of 19 amino acids, on the healing rate, contraction and granulation tissue formation of experimental deep ,second-degree bums in guinea-pigs. MATERIALS AND METHODS Animals
Eight Hartley derived female guinea-pigs, weighing 350-4OOg were studied. They were kept in individual cages and fed regular chow and water ad libitwn. Burn wound model
Twenty-four hours before burning, the animal’s back was clipped and depilated under light anaesthesia (i.p. sodium pentobarbital, 15 mg/kg). Two uniform burns were inflicted (after i.p. injection of sodium pentobarbital, 35 mg/kg) symmetrically on the back of the animals, using aluminium templates measuring 3.5 x 3.5cm, heated in a 75 “C water bath for 1 hour, and applied for 8 s to the moistened skin. Preliminary studies in our laboratories employing intra-aortic India ink injection demonstrated that this wound consists of a deep second-degree burn and confirming a similar burn model (Fang et al., 1982) The actual size of the burn wound was about 17cm2 due to contraction of the panniculus camosus muscle during the bum injury which involved about 4 per cent of the total body surface area.
Kaufmanet al.: Topical hyperalimentation
Revital Revital (Robertson Resources Ltd, Salisbury, MD, USA) is a mixture of 19 amino-acids (Table I) extracted from immature chicken feet. In the powder form which was employed in the present study, Revital has a pH of 4.6 when dissolved in water, a total water and nitrogen content of 7.9 and 1573 g per cent respectively and 6.10 g per cent of ash. The powder is hygroscopic, attracts water and moisture from the burn wound surface, and tends to be ‘muddy’ adhering to the wound. The agent is removed by saline irrigation. Tab/e I. Amino acid composition of Revital (mg per cent) Aspartic acid Glutamic acid Histidine Lysine Hydroxylysine Proline Hydroxyproline Arginine Threonine Serine
5.51 IO.24 0.81 3.80 I.19 11.83 IO.14 8.01 2.26 2.86
Tyrosine Glycine Cvstine Aianine Phenylalanine Methionine Leucine lsoleucine Valine
0.73 23.41 0.73 9.14 2.23 1 ,24 3.00 1.76 2.43
Mode of treatment Revital was applied to the right burn wound injury in the amount of 3 g per 17.76crn’ of burn area and changed every three days. To the contralateral control burn wound, Silvadene (1 per cent silver sulphadiazine cream, Marion Lab. Inc., Kansas City, MI, USA) was applied at a similar dose and dressings were changed every 3 days. Both wounds on each animal were separately dressed with a non-adhesive sterile Telfa dressing, (Kendall Company, Boston, MA, USA). Assessment of wound healing Evaluation of the open wound area, as well as that enclosed by the normal, hair bearing skin, was carried out employing the macrophotography technique (Kaufman et al., 1982) Areas were measured with a compensating polar-planimeter. The healing rate was monitored every 3 days for a total period of 24 days. Wound epithelialization as a per cent of the original wound size, was calculated employing the following formula: E=_-
A,-&
x 100,
4 where E = rate of epithelialization A, = area enclosed by the normal,
in per cent; hair bearing
skin on a given post burn day; A, = area of open wound on the same day as was measured. Wound contraction was calculated using the following formula:
c=- A, ---Anx 100. where C = rate of burn wound contraction expressed in per cent; A, = burn area as measured immediately following the burn injury; A, = area enclosed by normal, hair bearing skin. Morphology The animals were sacrificed on post-burn day (PBD) 24, and four punch biopsies (2mm in diameter) were taken from representative and comparable mirror image areas from the treated and control burn wound scars in each animal. Assessment of scar and epidermal thickness and volume Since collagen synthesis evaluation in resurfacing bum wound models is unreliable (Kaufman, 1982, unpublished data), measurements of the thickness of the newly formed scar tissue and its volume as well as that of the epidermal layer were carried out instead. Quantitation of the granulation and scar formation employing this approach provides an accurate estimation of the total amount of the newly formed scar tissue composed of newly deposited collagen as well as the cell-producing collagen population. Three segments of the scar tissue with their corresponding epidermal layers have been measured by means of an eyepiece micrometer in two adjacent sections from the centre of each punch biopsy. The volumes of the scar and epidermal layers were calculated by multiplying their thickness by the size of the wound on PBD 24. Analysis of data The analysis of variance was employed to assess the difference in the rate of epithelialization and contraction of the Revital and Silvadene treated wounds. The Student’s t test was used to evaluate the difference in wound healing on PBD 24 as well as for the difference of tissue thickness. RESULTS The mean burn size fs.e.m. of the Revital and Silvadene treated wounds following the burn injury were 17.76 + 1.34cm2 and 17.76kO.93 cm2, respectively. The mean per cent of healing rate +s.e.m. of the Revital-treated burns on PBD 9, 15, 18 and 24 were 41.78k1.35; 73.97k2.71;
254
BurnsVol. 1 O/No. 4
83*19+_3.24 and 94.34 + 1.81 respectively, and that of the Silvadene-treated wounds were 51.75 + 1.56; 86.96 + 2.61; 99.05 kO.94 and 100 respectively (Table II). The Silvadene-treated burns healed faster than the Revital-treated wounds (P ~0.005). The contraction rate on both tested burn wounds was similar (Table ZZZ)except on PBD 12 in which the Silvadene-treated bums contracted significantly more than the Revital treated wounds (P < 0.05). Table II. The rate of epithelialization (per cent) PBD
Silvadene
Revital
9 12 15 18 21 24
51.75i1.56’ 73.80*1.30’ 86.96h2.61 t 99.05*0.94t 1oo.oot 1oo.oot
41.78&l ,35 57.24i1.89 73.97*2.71 83.19k3.24 89.49*3.03 94.34il.81
‘P
t/J
Table Ill. The rate of contraction (per cent) PBD 6 9 12 15 :: 24 ??
Silvadene 80.91*3.88’ 68.73*3.26t 54.52*2.21$ 47.92*2,95t 42.35*3.01 35.79i3.47’ 23.70*3.75=
No significance; tP
Revital
??
83.62i3.07 61.74i2.84 45.4oi1.90 40.87k3.13 36.99i3.32 31.31*3.88 21.05i2.96
SPiO~O5.
There were 192 measured thicknesses of the newly formed scar tissue and epidermis in each test group of bum wounds. The Revital-treated bums consistently had a thicker scar than the Silvadene-treated wounds. The mean thickness of the newly formed scar tissue +s.e.m. on PBD 24 for the Revital and Silvadene-treated bums was 0.558 kO.103 mm and 0.288 &O.l38mm, re-
spectively (P
The healing process of our burn wound model consisted of epithelialization, contraction and formation of granulation and scar tissue. The epithelialization rate of the Silvadenetreated bums was significantly faster than the Revital-treated wounds. We assume that the hygroscopic effect of Revital delayed to some extent the mitosis and migration of the epidermal cells in this bum wound model. On the other hand, the moisture provided by the Silvadene to the control bums promoted epithelialization. Contraction of the wounds proceeded at a similar rate in both test groups, except on postburn day 12, in which the Sil.vadene-treated burns contracted more than the Revital wounds. We attribute this observation &‘some methodological error and speculate that both agents did not differ in their effect or lack of effect on the contraction rate of this burn wound model. Clinical studies suggested that topical hyperalimentation promoted the formation of a well vascularized granulation tissue of deep burns (Viljanto et al., 1976; Silvetti, 1981). In a controlled study, Niinikoski et al. (1977) has indicated that local hyperalimentation with amino acids, electrolytes and vitamins, significantly enhanced fiydroxyproline synthesis as well as the total number of cells in the newly formed granulation tissue, as reflected by the increased amount of DNA. In this study the investigators contrived a wound model in which granulation tissue grew into a subcutaneously implanted sponge in rats. Our burn wound model is also an injury deprived of nutritional substances and tissue oxygen due to ischaemia.
Table IV. Quantitative assessment of scar tissue and epidermal formation on PBD 24 Granulation tissue Volume Thickness (cm’) (mm) Revital Silvadene
0.558+0,103t 0.288*0.138
* No significance; tPcO.001.
0.099t 0.051
Epidermis Thickness Volume (cm3) (mm) 0.156*0.009* 0~145*0~012
0.027 0.025
255
Kaufmanet al.: Topical hyperalimentation
Since accurate quantification of collagen synthesis is not available to us, we measured the thickness and volume of the newly formed scar and granulation tissue. The Revital-treated burns exhibited a 1.9-fold thicker scar than the Silvadene-treated control wounds. Clinically this situation is undesirable. Our observations support the findings of others (Silvetti, 1981; Viljanto et al., 1976). We do not know why Revital caused an increase of granulation and scar formation in our burn wound model. Perhaps, it was due to chemical irritation of the burn wound as Revital has a pH of 4.6. It has been shown that acidification of wounds promoted healing and significantly increased the PO, of wound surface ‘by virtue of an appropriate shift in the oxyhaemoglobin-haemoglobin dissociation curve’ (Leveen et al., 1973). Increased availability of oxygen might increase the levels of pH in the wound as well as that of the intracellular compartment due to enhancement of the aerobic metabolism. Moreover, it has been suggested that a rise of the intracellular pH might serve as a signal for certain cells to divide and increase DNA and protein synthesis (Marx, 198 l), possibly through the production of a growth factor that stimulates a subset of the cell population to divide. We speculate, therefore, that the Revital’s low pH contributed to the formation of a thicker layer and volume of scar tissue. Perhaps, the hygroscopic effect of Revital might have significantly decreased the oedema in the burn tissue and hence, blood flow through the capillary bed was less affected by the thermal
injury sequelae than the Silvadene-treated burns. Therefore, the wound might reach higher PO2 tensions and hence, stimulate collagen synthesis. In fact, other investigators added to the amino acid mixtures some agents which possibly reacted as hygroscopic agents (Silvetti, 1981; Bergman et al., 1983). The multiple variables employed concurrently in the reported studies, should be carefully considered in order to accept the concept that topical hyperalimentation promotes healing and granulation tissue formation. The variables are listed in Table V. Niinikoski et al. (1977) postulated that local hyperalimentation promotes the number of collagen production cells as well as collagen synthesis. Using a similar mixture of amino acids, electrolytes, glucose and vitamins, Viljanto et al. (1976) suggested that tissue levels of adenosine triphosphatase were increased. None of the studies has proved that the nutrients topically applied were really incorporated by the granulation tissue cells. Therefore, one can assume that the effects of local hyperalimentation on wound healing and granulation and scar tissue formation could be attributed to some non-specific stimulations to the underlying connective tissue, possibly mediated by pH, hypertonicity and hygroscopy of the nutrient agent or by local mechanical factors. REFERENCES Bergman A., Yanai J., Weiss J. et al. (1983) Acceleration of wound healing by topical application of honey. An animal model. Am. J. Surg. 145, 374.
Tab/e V. Summary of the variables employed in different studies Vioanto (1976)
Niinikoski (1977)
Wound model
Open wounds, burns
Species Variables
Patients Salt sol.. vitam.,A.A. sol. sponges topically Unknown Unknown Unknown
Subcutaneous implanted sponges Rats Salt sol., vit., A.A. sol., sponges with dead space Unknown Unknown Unknown
PH Osmolarity Hygroscopic Results Closure wound Granul. tissue Other
ttt ATPase ttt
Hydroxyproline Ttt DNA tTT
(1981)
Bergman (1983)
Kaufman (7983)
Ch. open wounds, burns
Open wounds
Burns
Patients Salt & A.A. sol., D-glucose polysaccharide powder, vitamin C. 6.5 Unknown Possible
Mice
Guinea-pigs Amino-acid powder
m m
honey
3.6 Hypertonic Very potent
4.6 _ Potent
Delayed ttt
256 Fang C. H., Alexander J. W. and MacMillan B. G. (1982) Beneficial effects’of Hydron burn dressing on scar contraction and wound healing following deep partial-thickness bum injury. J.B.C.R. 3, 164. Kaufman T., Berlatzky Y. and Alexander J. W. (1982) The microclimate chamber for evaluation of the burn size and the rate of burn wound healing by serial photomacrography. Plast. Reconstr Surg. IO, 641. Leveen H. H., Falk G., Borer B. et al. (1973) Chemical acidification of wounds, an adjuvant to healing and the unfavorable action of alkalinity and ammonia. Ann. Surg. 178, 745. Marx J. N. (1981) Investigators focus on intracellular pH. Science 213, 745.
Burns Vol. 1 O/No. 4
Niinikoski J., Kivisaari J. and Viljanto J. (1977) Local hyperalimentation of experimental granulation tissue. Acta Chir. Stand. 143, 2OF.
Silvetti A. N. (1981) An effective method of treating long-enduring wounds and ulcers by topical application of solutions of nutrients. J. Dermatol. Surg. Oncol. 7, 501. Viljanto J. and Raekallio J. (1976) Local hyperalimentation of open wounds. Br. J. Surg. 63, 427.
Paper accepted 13 October 1983.
Correspondence shouldbe addressed fo: T. Kaufman MD, Department of Surgery (Plastic), University of Pittsburgh School of Medicine, The Monte&are Hospital, 3459 Fifth Avenue, Pittsburgh, Pennsylvania 15213 USA.