Use of a helium-oxygen mixture in the treatment of postextubation stridor in pediatric patients with burns

A mixture of helium and oxygen is less dense than room air. This property allows the gas to flow with less turbulence past airway narrowings, thereby decreasing airway resistance and increasing the volume of gas exchange. Previous studies demonstrated that airway obstruction that is manifested by stridor was present in 92% of patients requiring reintubation. Eight pediatric patients with burns in whom postextubation stridor or retractions unresponsive to racemic epinephrine developed, were treated with "heliox" (helium and oxygen) for 28 +/- 5 hours with an initial helium concentration between 50% and 70%. Of the eight patients treated with heliox, only two experienced respiratory distress and required reintubation. Both patients had stridor for a longer time before the initiation of heliox therapy compared with those patients who did not require reintubation. After initiation of heliox therapy, patients experienced a significant decrease in respiratory distress scores (6.8 +/- 0.7 vs 2.0 +/- 0.7). Heliox was able to relieve persistent stridor and thereby aid in the prevention of respiratory distress and reintubation.

Maintenance of serum albumin levels in pediatric burn patients: a prospective, randomized trial

A prospective, randomized trial was performed to determine whether maintaining serum albumin levels in burned pediatric patients had any effect on morbidity and mortality. Patients < 19 years of age with burns > 20% total body surface area were randomized to receive supplemental albumin to maintain levels 2.5 to 3.5 g/dL ("High Albumin") or were given albumin only if levels dropped < 1.5 g/dL ("Low Albumin") after completing burn shock resuscitation. The 36 patients in the Low Albumin group were well matched for age, burn size, depth of injury, and inhalation injury when compared with the High Albumin group (34 patients). As expected, serum albumin levels were significantly lower in the Low Albumin group when compared with the High Albumin group. No differences between groups were noted for resuscitation needs, maintenance fluid requirements, urine output, tube feedings received, days of antibiotic treatment, or ventilatory requirements. No differences in hematology, electrolytes, or nutritional laboratories were found. Finally, length of stay, complication rate, and mortality were not affected by albumin treatment. Albumin supplementation to maintain normal serum levels does not seem to be warranted in previously healthy children who suffer severe burns and who receive adequate nutrition.

Regulation of vascular endothelial growth factor expression in cultured keratinocytes. Implications for normal and impaired wound healing

Recent in situ hybridization studies had demonstrated a strong increase in vascular endothelial growth factor (VEGF) mRNA expression in the hyperproliferative epithelium during wound healing. To determine potential mediators of VEGF induction during this process, we analyzed the regulation of VEGF expression in cultured human keratinocytes. We found a large induction of VEGF expression upon treatment of quiescent cells with serum, epidermal growth factor, transforming growth factor-beta 1, keratinocyte growth factor, or the proinflammatory cytokine tumor necrosis factor alpha, respectively. Since all these factors are present at the wound site during the early phase of wound healing, they might also be responsible for VEGF induction after cutaneous injury. To determine the importance of increased VEGF production for wound repair, we compared the time course of VEGF mRNA expression during wound healing of healthy control mice with the kinetics of VEGF expression during skin repair of genetically diabetic db/db mice which are characterized by impaired wound healing. In normal mice we found elevated VEGF mRNA levels during the period when granulation tissue formation occurs. In contrast, VEGF mRNA levels even declined during this period in db/db mice, suggesting that a defect in VEGF regulation might be associated with wound healing disorders.

Capillary morphogenesis during healing of full-thickness skin grafts: An ultrastructural study

Biologic mechanisms by which skin grafts become revascularized after transplantation are poorly understood. To investigate graft revascularization, we examined the pattern of capillary growth in full-thickness skin grafts at serial time points. Full-thickness skin (2 x 2 cm) was excised to muscle fascia from the bilateral hind limbs of adult male Lewis rats. The graft/wound base boundary was identified by placement of a polypropylene mesh on the wound beneath the graft. Excised skin was replaced in its original orientation and secured with silk sutures tied over a gauze bolster dressing. After 3, 5, 7, and 10 days, animals were killed, and their aortas were cannulated and infused with an acrylic polymer to generate vascular casts. Grafts were excised, tissues were digested, and casts were examined with the use of scanning electron microscopy. Transmission electron microscopy was performed on tissues infused with the acrylic polymer that were not digested. At day 3, an immature lobular pattern was observed extending from the neovascular plexi on the graft side of the polypropylene mesh. At day 5, defined vessels with lobular ends occurred with high frequency. At day 7, the number of observed lobular structures was greatly reduced, and high frequencies of depressions in acrylic casts suggested protrusion of endothelial cell nuclei. By day 10, lobular structures were rare, well-defined microvascular plexi were contiguous with larger vessels, and depressions from endothelial cell nuclei appeared more shallow and less frequent. These findings suggest that (1) an immature lobular pattern representing either capillary outgrowth or extracapillary leakage occurs at day 3; (2) these immature lobules decrease, and more discrete capillaries increase by day 5; (3) vascular integrity is reestablished by day 7; (4) vascular plexi has regained full continuity, and there are suggestions that endothelial cell proliferation has subsided by day 10.

The use of extracorporeal life support in pediatric burn patients with respiratory failure

Respiratory failure is the most common cause of death after thermal injury and may be caused by inhalation injury, acute respiratory distress syndrome (ARDS) or pneumonia. ARDS is usually associated with sepsis; however, it may also occur during burn shock, especially in patients that have a delayed or inadequate fluid resuscitation. During the past 24 months, five pediatric burn patients underwent extracorporeal life support (ECLS) for respiratory failure unresponsive to optimal medical management. The mean age of the patients was 26 months (range, 8.5 to 48 months), with a mean burn size of 46% TBSA (> 95% third degree). The etiology of the respiratory failure included severe bronchospasm in a 22-month-old former premature infant with bronchopulmonary dysplasia; three patients with ARDS; and one patient with a severe inhalation injury. All five patients required greater than 56 cm H2O peak pressures and 100% FIO2 at the time of beginning ECLS. The oxygenation index (OI) ranged from 45 to 180. Three (60%) of the patients survived. In the three patients who ultimately survived, significant improvements in pulmonary and hemodynamic parameters occurred within 96 hours of ECLS. The two patients who died showed no improvement and were removed from ECLS at 10 and 11 days; both expired within hours. The patients who expired developed significant hemodynamic instability, coagulopathy, and hemorrhage from their burn wounds. The extent and degree of burn injury did not seem to alter the outcome. Indications for considering ECLS in the pediatric burn patient are unmanageable, life threatening pulmonary insufficiency in patients that undergo a relative short course of pre-ECLS ventilator support.(ABSTRACT TRUNCATED AT 250 WORDS)

Pigmentation and microanatomy of skin regenerated from composite grafts of cultured cells and biopolymers applied to full-thickness burn wounds

Rapid coverage and epithelial closure of extensive burns remains a major requirement for patient recovery. Although many skin substitutes have been described, permanent regeneration of both epithelial and connective tissues after a single surgical application of a skin substitute has not become routine. To replace both dermal and epidermal skin, cultured skin substitutes (CSS) were prepared from autologous keratinocytes and fibroblasts seeded onto collagen-glycosaminoglycan (C-GAG) substrates. CSS were applied to excised, full-thickness burns on 5 patients. Histologic analysis showed a fully stratified, hyperkeratotic epidermis within 12 days of grafting with little to no evidence of an inflammatory reaction. Epidermal and connective tissues are interdigitated in analogy to rete pegs and dermal papillae, and the neovascular plexus approximates the dermal-epidermal junction. Transmission electron microscopy identified a continuous basement membrane with hemidesmosomes and anchoring fibrils that connected the epidermis with the underlying connective tissue. Within 14-28 days, the C-GAG had been degraded and replaced by newly synthesized collagen in regenerated connective tissue. Spontaneous repigmentation of healing CSS from passenger melanocytes in keratinocytes culture was observed within 2 months after grafting. Electron microscopy revealed the presence of numerous melanosomes within the keratinocytes, illustrating pigment transfer between melanocytes and keratinocytes after wound closure. These results demonstrate that the CSS develop into functional permanent skin tissue capable of spontaneous repigmentation after grafting onto burn wounds.

Topical nutrients promote engraftment and inhibit wound contraction of cultured skin substitutes in athymic mice

Routine treatment of burns with cultured skin substitutes (CSS) has been limited by poor engraftment and by scarring. Hypothetically, topical application of essential nutrients and/or growth factors may support epithelial survival temporarily during graft vascularization. CSS, composed of human epidermal keratinocytes and dermal fibroblasts attached to collagen-glycosaminoglycan substrates, were incubated for 19 d in media optimized for keratinocytes. CSS, human xenografts, murine autografts, or no grafts were applied orthotopically to full-thickness skin wounds (2 x 2 cm) in athymic mice. Wounds were irrigated for 14 d with 1 ml/d modified cell culture medium or with saline containing epidermal growth factor, or were treated with dry dressings. After 6 weeks, treated sites were scored for percentage original wound area (mean +/- SEM) and percentage HLA-ABC-positive healed wounds [(number positive/n) x 100], and tested for significance (analysis of variance, p < 0.0001; Tukey test, p < 0.05). The data showed that CSS irrigated with nutrient medium were not statistically different in wound area (67.8 +/- 5.1%) from murine autografts (63.3 +/- 2.9%) but were statistically larger than human xenograft, no graft, or CSS treated with saline irrigation or dry dressings. HLA-ABC expression was 100% in CSS with nutrient irrigation, 86% in CSS with saline irrigation, 83% in CSS without irrigation, and 75% in xenografts with nutrient irrigation. These findings suggest that availability of essential nutrients supports keratinocyte viability during graft vascularization of CSS.

Wound healing in the transforming growth factor-beta1-deficient mouse

To investigate the role of transforming growth factor-beta(1) in tissue repair, we performed wound healing studies in the transforming growth factor-beta(1)-deficient mouse with targeted disruption of the transforming growth factor-beta(1) gene. Transforming growth factor-beta(1)-deficient mice exhibit no obvious developmental defects and are phenotypically normal until approximately 3 weeks of age when a severe wasting syndrome develops, accompanied by an overwhelming inflammatory response resulting in multisystem organ failure and death. Full-thickness 0.5 x 0.5 cm skin wounds were created on the backs of 10-day-old mice (wild type or heterozygous controls versus homozygous transforming growth factor-beta(1)-deficient mutants) and covered with a nonabsorbent dressing (OpSite). Serial wound measurements were made, and percentage of wound closure over time was determined. On day 10, wounds and liver were harvested for histologic and molecular analysis. Histologic scores were assigned (1 [no healing] to 12 [complete healing]) on the basis of granulation tissue formation, vascularity, collagen deposition, and epithelialization. Reverse transcription-polymerase chain reaction was performed to detect messenger RNA transcripts for transforming growth factor-beta(1), transforming growth factor-beta(2), platelet-derived growth factor A-chain and B-chain, interleukin-1beta and -6, and tumor necrosis factor-alpha in unwounded skin, day 10 wounds, and liver. No significant differences in wound closure were observed until day 10. Weight gain, however, was significantly decreased in the mutant animals as early as day 6. Histologic scores were significantly lower in the transforming growth factor-beta(1)-deficient mutants (5.4 +/- 0.6 versus 11.1 +/- 0.3, p < 0.01, Wilcoxon rank-sum test) and showed decreased granulation tissue formation, vascularity, collagen deposition, and epithelialization and a marked inflammatory infiltrate. As expected, transforming growth factor-beta(1) was expressed in controls but not mutants. Transforming growth factor-beta(2), platelet-derived growth factor A-chain and B-chain, and tumor necrosis factor-alpha were constitutively expressed in unwounded skin, day 10 wounds, and liver of both controls and mutants. Interleukin-1beta and -6, however, were induced after wounding. Early wound healing in the transforming growth factor-beta(1)-deficient mouse proceeds relatively normally because of upregulation or functional redundancy of other growth factors or possibly because of maternal rescue by means of transforming growth factor-beta(1) transmitted in milk. Loss of transforming growth factor-beta(1) regulation ultimately results in a marked inflammatory response, as evidenced by the histologic appearance of the wound and increased expression of the inflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta and 6). The severe wasting syndrome (marked by weight loss) undoubtedly has an adverse effect on wound healing.

The adequacy of limb escharotomies-fasciotomies after referral to a major burn center

To determine the frequency of inadequate decompression and its complications, the medical records of 108 pediatric burn patients requiring escharotomies or fasciotomies were reviewed. Of 108 patients, 100 (93%) had escharotomies or fasciotomies performed at an outlying facility before transfer. Of these 100 patients, 44 (117 limbs) were inadequately decompressed and required further decompression after admission to our facility. Initial mean compartment pressures were 50.3 +/- 1.3 mm Hg, which were reduced to 16.3 +/- 0.5 mm Hg after decompression. Pulses were present in 74% of limbs requiring decompression. Twenty limbs required decompression despite noncircumferential burns. Complications of inadequate or delayed decompression included foot drop in 20 patients (35 limbs) and muscle necrosis in 13 patients (23 limbs). Four patients (seven limbs) required amputations because of progressive muscle necrosis and infection. Complications of the procedure itself were limited to bleeding in three patients. In conclusion, compartment pressures should be followed in patients with significant burns since pressures may increase over time and pulses are not predictive of ischemia. Failure to decompress extremities with elevated pressures leads to significant but preventable complications.

Improved ventilatory function in burn patients using volumetric diffusive respiration

BACKGROUND

Volumetric diffusive respiration (VDR) offers theoretical advantages over conventional mechanical ventilation (CV) by using lower airway pressures, recruiting alveoli, and mobilizing secretions.

STUDY DESIGN

Forty-eight thermally injured pediatric patients with failing respiratory status were changed from CV to VDR. Data were obtained just before transition for CV and after stabilization on VDR, within six hours of transition.

RESULTS

Both ventilation and oxygenation were significantly improved with PaCO2 decreasing from 47 +/- 3 to 39 +/- 11 mm Hg and PaO2 increasing from 105 +/- 8 to 171 +/- 12 mm Hg after transition to VDR. Treatment with the VDR ventilator also resulted in a significant decrease in peak inspiratory pressures (PIP) from 52 +/- 2 to 38 +/- 2 cm H2O. The PaO2 to FiO2 ratio increased from 189 +/- 16 using CV, to 329 +/- 21 using VDR, suggesting an improvement in the ventilation and perfusion matching. Ventilatory efficiency, measured by the PaO2/FiO2/PIP ratio, greatly improved after transition from CV to VDR with fraction of inspired oxygen increasing from 3.9 +/- 0.4 to 10.3 +/- 1.0. Hemodynamic function (blood pressure and pulse rate) were not adversely affected by VDR.

CONCLUSIONS

The VDR ventilator is more effective than conventional ventilation for maintaining optimal gas exchange at lower airway pressures in thermally injured pediatric patients.

Induction of keratinocyte growth factor expression is reduced and delayed during wound healing in the genetically diabetic mouse

We have recently demonstrated induction of expression of several members of the fibroblast growth factor family during wound healing, particularly for keratinocyte growth factor, which was more than 150-fold induced within 24 h after injury. To assess whether wound-healing disorders are associated with a defect in fibroblast growth factor regulation, we have now investigated the expression of these mitogens as well as their receptors in normal and wounded skin of genetically diabetic db/db mice, which are characterized by their impaired wound healing. We demonstrate that induction of keratinocyte growth factor expression in these mice is significantly reduced and delayed compared to normal mice. Induction of acidic fibroblast growth factor (FGF) and basic FGF expression was earlier in diabetic mice than in normal mice, but by 3 d after injury expression of these mitogens had already returned to the basal levels. In contrast, elevated levels of acidic FGF and basic FGF transcripts were detected within the first 5 d in wounds from normal mice. Thus, FGFs seem to be expressed in a limited fashion in the wound tissue of db/db mice during the period when re-epithelialization and granulation tissue formation normally occur. These findings provide an explanation for the beneficial effect of exogenous FGF in the treatment of impaired wound healing in these animals and suggest that induction of KGF early in repair may be critical for the rapid re-epithelialization in normal wound healing.

A prospective study of burn scar maturation in pediatrics: does age matter?

A prospective study was performed to determine whether patterns of burn scar maturation varied among different pediatric age groups. Patients were divided into three groups according to age at the time of burn injury: birth to 3 years, 4 to 11 years, and 12 to 18 years. Scarring of sheet grafts on an extremity was assessed throughout the maturation process in three areas: vascularity, pliability, and height. A 1-inch square was selected on the graft edge adjacent to unburned skin. Two experienced therapists independently evaluated the test area and averaged their scores. There were no significant differences in rate of scar maturation between age groups. Burn scar maturation of sheet skin grafts in the pediatric patient with burns demonstrated a rapid peak of scarring (1 to 2 months) and scar maturation (9 to 13 months).

Cardiac abnormalities in children with burns: an autopsy analysis

After observing several cases of endocarditis-related deaths, we determined the contribution of cardiac abnormalities to burn mortality. Autopsy reports of all burn-related deaths between 1964 and 1992 (n = 212) were reviewed for cardiac disease. Cardiac abnormalities were categorized into infectious, acquired, or congenital. Cardiac abnormalities of all forms were associated with longer hospitalizations before death and affected a larger proportion of females than expected in the male-dominated burn population. The highest incidence of endocarditis (17.3% of all deaths) occurred in the past 5 years. The frequency of other forms of cardiac abnormalities has not changed over time. Improved burn management has resulted not only in improved survival but has also prolonged the duration of hospitalization of those patients who ultimately die of their injuries. As patients are kept alive for longer periods, the incidence of endocarditis and the cardiac manifestations of multiple organ failure have increased.

PDGF and TGF-alpha act synergistically to improve wound healing in the genetically diabetic mouse

Impaired wound healing results in significant morbidity for the surgical patient. The genetically diabetic (C57BL/KsJ-db/db) mouse is obese, hyperglycemic, insulin-resistant, and exhibits markedly impaired wound healing. Previous studies have demonstrated that the fibroblast mitogens, BB homodimer of platelet-derived growth factor (PDGF-BB) or basic fibroblast growth factor, plus insulin-like growth factor, act synergistically to enhance wound closure in the genetically diabetic mouse. The purpose of this study was to determine whether the keratinocyte mitogens, epidermal growth factor (EGF) or transforming growth factor-alpha (TGF-alpha), in combination with the fibroblast mitogen, PDGF-BB, would produce a similar synergistic enhancement in tissue repair. Full-thickness skin wounds created on the backs of diabetic mice received topical applications of vehicle (5% polyethylene glycol), PDGF-BB (10 micrograms), EGF (1 microgram), TGF-alpha (1 microgram), or the combination of PDGF (10 micrograms) and EGF (1 microgram) or TGF-alpha (1 microgram) for 5 consecutive days starting at wounding. Application of PDGF-BB or TGF-alpha alone to wounds in diabetic animals improved wound closure when compared to vehicle treatment. EGF did not affect healing and did not have any additive effects when combined with PDGF-BB. Significant improvements in wound closure were observed with the combination of PDGF-BB and TGF-alpha when compared to treatment with the individual growth factors. The PDGF-BB/TGF-alpha combination accelerated healing in the diabetic animals to a rate that was closer to that seen in nondiabetic mice.(ABSTRACT TRUNCATED AT 250 WORDS)

The importance of intra-abdominal pressure measurements in burned children

Four burned children suffering complications from elevated intra-abdominal pressures prompted initiation of a prospective study to determine the value of intra-abdominal pressure measurements in 30 children with large burns. Intra-abdominal pressures were measured every 4 hours during burn shock or sepsis, or daily during periods of stability. Patients were arbitrarily divided into those having one or more measurements > or = 30 mm Hg or all values < 30 mm Hg. Patients in the > or = 30 mm Hg group had significantly larger burns, higher mortality, and increased instances of sepsis. Five patients had elevated intra-abdominal pressures during burn shock, with two requiring abdominal escharotomies. Seven were at > 30 mm Hg during sepsis, with three requiring paralysis, and one each requiring placement of a peritoneal catheter or laparotomy. Significant intra-abdominal pressure elevations may occur in patients with extensive burns and are associated with a poorer prognosis. Elevation of intra-abdominal pressure should be considered in severely burned patients with oliguria, hypoventilation, or hypotension.

Delivery and activity of antimicrobial drugs released from human fibrin sealant

Engraftment and healing of native or cultured skin grafts depend on adherence, vascularization, and control of microbial contamination in the wound bed. Fibrin sealant is a biocompatible polymer that may be used to promote skin engraftment by serving as a delivery vehicle for antimicrobial drugs. Human fibrin sealant (25 mg/ml) was polymerized with antibacterial agents (mupirocin [32 micrograms/ml], nitrofurazone [0.02% wt/vol], polymyxin B [400 U/ml], or norfloxacin [20 micrograms/ml]) on nitrocellulose (nc) backing and was prepared as 6 mm diameter discs with skin punches. Discs (n = 6) were applied in the Wet Disc Assay to clinical isolates of Staphylococcus aureus (mupirocin, nitrofurazone) or Pseudomonas aeruginosa (polymyxin B, norfloxacin). Controls included drug applied to 6 mm paper discs (25 microliter) and nitrocellulose discs submerged in each drug, blotted, and applied to bacterial cultures on agar in petri dishes. Data were expressed as zone of clearing (mm diameter +/- SEM) after overnight incubation at 35 degrees C. Significant differences (ANOVA and Turkey's test, p < 0.05) were found for each drug released from the disc of fibrin sealant compared with other vehicles. Release from filter paper discs compared with nitrocellulose was significant for nitrofurazone and norfloxacin. Serial transfer of fibrin discs to fresh bacterial cultures after 24 hours showed no zones of clearing. The data show that fibrin sealant releases topical drugs with no inhibition of antimicrobial activity on burn organisms. Greater zones of clearing from fibrin sealant may result from passive fluid retention or from active binding to fibrin followed by protease digestion by burn organisms.(ABSTRACT TRUNCATED AT 250 WORDS)

The management of perineal contractures in children with burns

A retrospective review of patients undergoing reconstruction for perineal scar contracture between 1980 and 1991 was performed to determine the surgical principles involved in perineal contracture release. Of the 5280 reconstructive admissions, 18 (0.34%) were for perineal contracture release. Fifty-six percent of patients received a local flap as an initial release, 28% underwent incisional release with split-thickness skin grafting (STSG), 5% had primary release and closure, and 11% had a combination of these techniques. Recurrences developed in 40% of the local flap group, 20% of the STSG group, and 50% of the combination group, with no statistical differences between groups. Although there was a higher rate of recurrence in the flap group, the procedure was much simpler to perform and recovery time was shorter. The use of STSG should be reserved for large bilateral contractures and recurrences, especially if normal skin for a flap is not available. Growth is an important variable in the development of perineal contractures in children with burns; thus these patients should be followed up closely during rapid-growth periods.

Effects of basic fibroblast growth factor on the healing of partial-thickness donor sites. A prospective, randomized, double-blind trial

A phase I/II clinical study was performed to evaluate the safety and potential efficacy of topical recombinant human basic fibroblast growth factor on the healing of partial-thickness skin graft donor sites in burned children. Each child served as his or her own control. In a blinded and random fashion, one donor site was sprayed with basic fibroblast growth factor (5 microg/cm(2)) on days 0 to 4 after harvest, whereas the other site was treated with vehicle. Twelve patients were entered in the study but one patient died of sepsis that was unrelated to growth factor treatment. Of the remaining 11 patients, no adverse events related to basic fibroblast growth factor occurred. Serum basic fibroblast growth factor levels were never detected and antibody levels remained unchanged. No differences in the rate of epithelialization or days until complete closure were noted (basic fibroblast growth factor = 12.9 +/- 3.9 days, placebo = 12.2 +/- 5.5 days; mean +/- standard error of the mean). No differences in pain, itching, wound fragility, erythema, scarring, or pigmentation were noted. All of the scars matured within 1 year with good to excellent results. Investigators, patients, or families could not distinguish between the two wounds. Although basic fibroblast growth factor proved safe, no enhancement of donor site healing was seen in this small study. Because the time for donor site healing limits subsequent autograft use in patients with sizeable burns, studies should focus on accelerating healing in patients with larger burns where donor site healing is delayed and reharvest is required.

PDGF and FGF reverse the healing impairment in protein-malnourished diabetic mice

BACKGROUND

Growth factors have been shown to improve healing in impaired models but not after malnutrition. The effects of growth factors on altered tissue repair caused by malnutrition were examined.

METHODS

Nondiabetic and diabetic mice fed a 1% protein diet received full-thickness skin wounds. Wounds were treated topically with vehicle, platelet-derived growth factor (PDGF, 10 micrograms) or basic fibroblast growth factor (bFGF, 1 microgram), for 5 days.

RESULTS

Malnourished animals developed significantly impaired wound closure. PDGF or bFGF did not enhance closure in nondiabetic C57BL/KsJ-db/m mice, whether fed normal or restricted diets. The same treatment regimen was effective in reversing the delayed wound closure in their genetically diabetic C57BL/KsJ-db/db littermates. The growth factors significantly enhanced tissue repair in diabetic mice fed a 1% protein diet starting as early as day 15 and continuing until day 21. Protein-depleted diabetic wounds had significantly decreased cellularity and granulation tissue formation. These deficiencies were reversed with growth factor treatment.

CONCLUSIONS

Despite the lack of effects in nondiabetic animals, growth factors improve healing in diabetic mice with restricted protein intake. The differential effects may result from different healing mechanisms: nondiabetic animals heal mainly by contraction; diabetic animals require granulation tissue formation and reepithelialization.

Skin anatomy and antigen expression after burn wound closure with composite grafts of cultured skin cells and biopolymers

Closure of large skin wounds (i.e., burns, congenital giant nevus, reconstruction of traumatic injury) with split-thickness skin grafts requires extensive harvesting of autologous skin. Composite grafts consisting of collagen-glycosaminoglycan (GAG) substrates populated with cultured dermal fibroblasts and epidermal keratinocytes were tested in a pilot study on full-thickness burn wounds of three patients as an alternative to split-thickness skin. Light microscopy and transmission electron microscopy showed regeneration of epidermal and dermal tissue by 2 weeks, with degradation of the collagen-GAG implant associated with low numbers of leukocytes, and deposition of new collagen by fibroblasts. Complete basement membrane, including anchoring fibrils and anchoring plaques, is formed by 2 weeks, is mature by 3 months, and accounts for the absence of blistering of healed epidermis. All skin antigens tested (involucrin, filaggrin, laminin, collagens IV and VII, fibronectin, and chondroitin-sulfate) were expressed by 16 days after grafting. This cultured skin analogue provides an experimental alternative to split-thickness skin graft that develops histiotypic markers of skin anatomy and antigen expression after wound closure.

Synergistic actions of platelet-derived growth factor and the insulin-like growth factors in vivo

Topical application of growth factors has been shown to benefit both normal and impaired wound healing. In normal tissue repair, resident cells produce a "cocktail" of various types of growth factors that overlap in function. In vitro studies have proved that growth factor combinations can act synergistically to enhance cellular function beyond that achieved with individual growth factors. To determine whether similar combinations have a synergistic effect in vivo, we applied growth factor combinations topically to full-thickness skin wounds created in genetically diabetic mice. The C57BL/KsJ-db/db mouse is obese and has insulin-resistant diabetes, and it has been proved that this mouse has markedly impaired wound healing. Topical application of platelet-derived growth factor, insulin-like growth factor-I, or insulin-like growth factor-II enhances healing in this model. Marked synergism was found when platelet-derived growth factor and insulin-like growth factor-II were combined to produce augmentation in wound closure beyond that achieved by application of the individual growth factors. The synergistic effect allowed for improved tissue repair at doses of platelet-derived growth factor and insulin-like growth factor-II that were ineffective when applied individually. The addition of insulin-like growth factor-I or insulin to platelet-derived growth factor produced no significant synergism. Because multiple growth factors are released in the wound during the healing process, it is not surprising that their combination further enhances healing. Growth factor combinations should become an important addition to the armamentarium for the treatment of chronic, nonhealing wounds.

Comparison of back versus thigh donor sites in pediatric patients with burns

To substantiate an observation that donor sites that are harvested from the back scar less than those that are harvested from thighs, donor sites from both areas were evaluated for the extent of scarring. For donor sites that were harvested more that 1 year before evaluation, no significant improvements were observed. Back donor sites that were evaluated less than or equal to 1 year after harvest had significant improvements in height, color, edema, suppleness, and cosmetic appearance than those harvested from thighs. Thirty-two patients had both back and thigh donor sites harvested at the same time. Back donor sites had significant improvement in scar height, color, and edema. Cosmetic improvements were also observed. Significantly more patients preferred the back donor site over that of the thigh. The back is the preferred donor site for skin grafts in the pediatric burn population.

The early release of axillary contractures in pediatric patients with burns

In spite of the common teaching that contracture releases should be avoided until scars have matured, the Cincinnati Shriners Burns Institute has been releasing contractures in immature scars to prevent prolonged loss of range of motion. To evaluate the efficacy of axillary releases and, especially, to determine whether releases performed in immature scars were detrimental, axillary releases that were performed between January 1, 1988 and December 31, 1989 were evaluated for improvements in abduction and flexion. Overall, axillary releases significantly improved abduction and flexion, and the improvement was maintained for at least 1 year. Comparison of early (less than 1 year after burn injury) with late (more than 1 year after burn injury) releases revealed that the preoperative limitation was worse in the early release group but that the ultimate outcomes were similar. Waiting for scars to mature before performance of contracture releases is not necessary.

A comparison of full-thickness versus split-thickness autografts for the coverage of deep palm burns in the very young pediatric patient

From 1984 through 1989, 24 patients with 30 acute palmar burns (six were bilateral) that required skin grafting were evaluated to compare the efficacy of split-thickness versus full-thickness autografting. Sixteen of the palms had split-thickness skin grafts and 14 had full-thickness skin grafts. Normal range of motion was found in 8 of 14 palms that were treated with full-thickness skin grafts and in 4 of 16 for those that were treated with split-thickness skin grafts. Significantly fewer reconstructive surgical procedures were required in the palm burns that were treated with full-thickness skin grafts (full-thickness = 3 of 14 and split-thickness = 10 of 16). The results demonstrate improved function and decreased need for reconstructive procedures when full-thickness skin grafts are used for the treatment of deep palm burns in young pediatric patients.

Outcome and socioeconomic aspects of suspected child abuse scald burns

Fifty-two children suffering from abuse-related scald burns were admitted between January 1, 1986, and June 30, 1991. Their clinical and socioeconomic aspects were compared with those of 50 nonabused scalded children. Patients were matched for age, total body surface area burn, and percentage of full-thickness burn. Patient characteristics and initial nutritional parameters were similar except for race; a higher percentage of black children were in the abused group. A significantly longer length of hospital stay was found in the abused children after using analyses of covariance to control for percentages of total and full-thickness body surface area burn. The number of operations and frequency of complications were increased in the abused group, but not significantly so. Several significant differences were found in the socioeconomic characteristics of the two groups. Children suspected of being scalded intentionally were more likely to be part of a broken home, belong to a single parent, and have a younger mother than were children in the control group. The majority of the parents of abused children were unemployed, and all but two earned less than $20,000/year. All but one of the abused children were discharged with a person other than their parents, and compliance with rehabilitation follow-up was significantly worse than with the control group. The person suspected of performing the abuse was always a family member, except in cases where the baby-sitter was the suspected abuser. Child abuse hurts not only the child but also society by increasing the need for resources to pay for extended hospital admissions.(ABSTRACT TRUNCATED AT 250 WORDS)