Inflammatory and oxidative stress after surgery for the small area corrections of burn sequelae

Purpose: To compare vitamin levels, inflammatory and oxidative stress markers before and after skin autograft surgery to correct burn scar areas. Methods: This prospective study was conducted with 8 patients with a median age of 28 years (range, 16 to 40 years) that had burn sequelae and were admitted to a Burn Unit for correction of small burn scar areas [3.3 (1.0-5.0) % of the corporal surface]. The volunteers were evaluated before and 48 hours after excision of scar tissue and skin autograft. Routine laboratory data, along with a food questionnaire and anthropometry were collected in the preoperative period. Serum vitamin A, C, E, B12 and folic acid levels, inflammatory markers (C-protein reactive, alpha-1-acid glycoprotein, ferritin) and oxidative stress markers (reduced glutathione GSH and Thiobarbituric Acid Reactive Substances TBARS) were determined at preoperative and postoperative phases. Data were analyzed with two-sample Wilcoxon test. Results: All volunteers were clinically stable and had adequate nutritional status at admission. After surgery, C-reactive protein serum levels increased [0.4 (0.01–1.0) vs. 2.5 (0.6–4.7) mg/dL, p=0.01] and vitamin A levels decreased [3.4 (2.1-4.2) vs. 2.4 (1.6-4.1) μmol/L, p=0.01]. No changes occurred in other vitamins, ferrritin, alpha-1-acid glycoprotein, GSH and TBARS levels. Conclusion: Minimal metabolic changes were produced after skin autograft in small areas of well-nourished patients without active infection or inflammation.


Introduction
The rate of survival after thermal injury has improved in the past two decades 1 but a large number of patients develop postburn scar contractures 2 .To restore anatomy and function, these patients require multistage correction surgery 3 that includes single scar release, use of skin grafts, skin expansion, regional or free musculocutaneous or fasciocutaneous flaps.
Although free radicals influence the bactericidal capacity of neutrophils and macrophages, they are likely to cause structural, functional and biochemical cellular changes, as well as modification of membrane permeability, mitochondrial dysfunction, and cell damage and death 4 .The antioxidant substances, which include enzymes such as superoxide dismutase (SOD) and catalase, and non-enzymatic antioxidants such as the carotenoids, ascorbate, vitamin E and reduced glutathione (GSH) 5 , are important to maintain low levels of free radicals.The antioxidants substances are critical to the organism survival and allow ischemic skin to recover from ischemia induced injury 6 .
Recent attention has been focused on the hypothesis that the accumulation of free radicals initiates a significant inflammatory response which includes the secretion of proinflammatory and anti-inflammatory cytokines that contribute to cellular injury 7 .
The inflammatory response may cause changes in vascular permeability, alteration in the coagulation system, impairment of gut function, hypermetabolic response, and immune depression 8 , anorexia, weight loss and tissue waste 9 .
Although the intensity of oxidative stress is known to interfere with the clinical course of victims of acute thermal trauma 10 , this aspect has not been evaluated after surgical reconstruction of postburn contractures.In animal models of skin ischemia, the intensity of local inflammatory response and an imbalance in the formation of free radical and antioxidant substances may be important in the clinical evolution as well as the survival of skin flaps 6 .It was hypothesized that small areas of skin autograft cause metabolic changes including the elevation of inflammatory and oxidative stress markers.Thus, the purpose of this study was to compare vitamin levels, inflammatory and oxidative stress markers before and after skin autograft for the correction of small burn scar areas.This study was approved by the Institutional Ethics Committee.Written informed consent was obtained from each subject and all patients received treatment according to the preexisting protocol.The surgery lasted about 60 minutes and the same plastic surgery and anaesthetic team were involved in all procedures.The exeresis of scar tissue was performed, followed by a skin autograft using healthy skin from the patient himself.

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A thin slice of skin (0.005-0.010 in) was removed from the donor region, whose dimensions vary according to the area to be repaired (Table 1), using a Padgett ® electric dermatome (Integra Lifesciences Corporate) or an Aesculap ® dermatome (B.Braun Melsungen AG Division).If necessary, the graft was submitted to an expansion process with the aid of an external skin expander (Brenner Medical, Inc.) in order to cover a greater extension of the injured area.The extent of the surgically injured area was determined by the rule of Lund and Browder immediately after the reparative surgical procedure, considering the sum of the skin surface obtained by the exeresis of the scar injury and of the skin donor area.
The Semi-quantitative Food Consumption Frequency Questionnaire was applied during the preoperative period in order to obtain information about food intake over the previous 6 months.Body weight and height were measured and the body mass index (BMI, kg/m 2 ) was calculated.Inflammatory stress markers (C-reactive protein, ferritin, acid α1-glicoprotein), serum vitamins The surgical procedures were not complicated.There were no adverse effects related to the exeresis of scar tissue and skin autograft and none of the patients developed contracture recurrence.Table 1 describes the volunteers´ demographic data, donor sites and deployed areas.The median total body surface area excised was 3.3% (range, 1.0-5.0%).
prospective study was conducted in 2007 and 2008 at the Burn Unit of a Brazilian University Hospital.Eight volunteers with a median age of 28 years (range, 16 to 40 years), being 4 males and 4 females, were submitted to correction of burn scar contractures.In order to eliminate the interference of inflammatory stress caused by the acute burn, only subjects whose thermal trauma had occurred at least one year before the study [2 (1-21) years] were included.Volunteers with diabetes, cardiovascular disease, hepatic insufficiency, chronic renal insufficiency, and use of systemic corticosteroids were excluded.

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A, C, E, B 12 and folic acid) and oxidative stress markers (GSH and Thiobarbituric Acid Reactive Species -TBARS) were evaluated on two distinct occasions, i.e., preoperatively (Preoperative Phase) and 48 hours after surgical exeresis of the lesions and skin autograft applying (Postoperative Phase).Serum C-reactive protein and acid α1-glycoprotein levels were determined by turbidimetry using commercial Cobas ® kits, and ferritin levels were determined by chemoluminescence.Serum levels of vitamins A and E were determined by HPLC (Shimadzu, model LC10A).Vitamin C was determined by colorimetry and the analysis of folic acid and vitamin B 12 were performed on IMMULITE ® .GSH was determined by the modified method of Sedlack and Lindsay 11 and TBARS levels were determined by Buege and Austi´s method 12 .Data analyses were performed with Statistica software (version 7.0, StatSoft Inc.).Variables were analyzed by twosample Wilcoxon test, and are reported as median and range.The significance level was set at p<0.05 in all analyses.Results None patients were taking supplemental vitamins.The daily nutrient intake was above the recommended dietary allowances regarding intake of energy [5433.8(2652.0-11913.3)kcal), protein [195.0 (94.9-428.8)g), mineral and vitamins, including vitamin A [2558.6 (684.0-4953.0)IU), C [375.8 (297.0-919.7)mg], E [22.2 (11.6-75.2) mg], B 12 [11.5 (1.7-74.4)µg] and folic acid [684.7 (263.0-1224.7)µg).During the preoperative period, the patients had normal range BMI values [23.4 (18.1-27.2) kg/m 2 ].Serum levels of clinical and nutritional biochemical indices before the surgical procedures were normal.

TABLE 1 -
Demographic data, donor sites and deployed areas of postburn contractures patients.Surgical procedure caused an increase in C-reactive protein (p = 0.01) but no changes in other inflammatory stress markers levels were documented.Except for a reduction in serum vitamin A levels (p = 0.006), the serum levels of the other vitamins remained stable after the surgical procedure (Table2).Reparative surgery did not cause any significant changes in serum GSH or TBARS concentrations.

TABLE 2 -
Inflammatory and oxidative stress markers and vitamin levels before and after the surgical procedure.