One hundred ninety-five cases of high-voltage electric injury.

High-voltage electric injury (HVEI) is associated with a high incidence of extremity compartment syndrome and of major amputation. The purpose of this study was to review our experience with HVEI and to attempt to develop predictors of the need for fasciotomy and amputation in patients with HVEI. The records of the 195 patients with HVEI who were admitted to a single burn center during a 19-year period were reviewed. Evidence for muscle necrosis, to include myoglobinuria and elevated creatine phosphokinase (CPK) levels, was noted. A total 187 patients (95.9%) survived to hospital discharge. A total of 56 underwent fasciotomy within 24 h of injury; 80 patients underwent an amputation during the hospitalization. Fasciotomy was predicted by presence of myoglobinuria with an overall accuracy of 72.8%. Amputation was predicted by a logistic model incorporating myoglobinuria, undergoing a previous fasciotomy, and age, with an overall accuracy of 73.3%. HVEI was associated with high amputation risk and a low rate of mortality in patients admitted to our burn center. Patients with gross myoglobinuria are at higher risk of requiring fasciotomy and/or amputation.

[Preliminary study on the release of DNA from Pseudomona aeruginosa induced by piperacillin/tazobactam in vitro].

OBJECTIVE: To observe the release of DNA from Pseudomonas aeruginosa (P. aeruginosa) induced by different concentrations of piperacillin/tazobactam (Piper) in vitro. METHODS: The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of Piper against 1244 strain (ATCC 27317) of P. aeruginosa were determined, respectively. This strain of P. aeruginosa was separately cultured with Piper in different concentrations at 37 degrees C for 4 h and 24 h. The samples of cultural supernatant were filtered and electrophoresis was conducted in 1.8% agarose with SYBR Gold stain. Then the images of the gel sheets were photographed. RESULTS: This strain of P. aeruginosa was sensitive to Piper. The bacterial DNA was not detected in 4-h cultured P. aeruginosa either with or without Piper by this method. The bacterial DNA molecules could be detected in 24 h samples in cultures without Piper, and they were displayed in two zones of molecular weight over 2000 base pairs (bp) and lower than 100 bp. Similar results were observed when the MIC of piper (0.002, 0.004 g/L) were under the MIC measured at the 3rd time (0.008 g/L), but there was much more bacterial DNA with molecular weight lower than 100 bp. When Piper concentration was higher than its MIC, only smaller quantities of bacterial DNA in the area with molecular weight lower than 400 bp could be detected in 24-h culture samples. CONCLUSION: A certain amount of bacterial DNA was released from P. aeruginosa under its natural growth circumstance. Different concentrations of Piper showed different effects on DNA release, in regard to its quantity and molecular weight, from P. aeruginosa cultures.

Topical silver treatment after escharectomy of infected full thickness burn wounds in rats.

White male Sprague Dawley rats (200 g.) with 20% full thickness scald burns seeded with 10 Pseudomonas aeruginosa, strain 59-1244, were used as experimental animals. Studies including the following: (1). Control groups. (2). DC pretreatment groups. (3). Treatment groups. P. aeruginosa infected burn wounds were excised, and then treated with either autograft or silver-nylon dressings, with (SNDC) or without (SN) application direct current. Excision and treatment were initiated 1, 2, 3, 4 or 5 days after burning and inoculation. (4). Groups for antimicrobial barrier function study. Mortality of each group was recorded at 21 days PB. With burns alone, there was no mortality. Without treatment 19 of 20 burn inoculated controls died. In the pretreatment study, the mortality of the group pretreated with SN was 95% while that of the group pretreated with SNDC was only 30%. With excision and autografting, PB mortality rose from 5/20 at day 2 PB to 19/20 at day 3 PB. In the excision and SN groups, mortality rose from 5/20 at day 3 PB to 18/20 at day 4 PB. In the excision and SNDC groups, mortality rose from 5/20 at day 3 PB to 18/20 at day 4 PB. In the antimicrobial barrier function study, the 10% mortality in the SN dressing group was significantly less than that of 95% in the plain nylon dressed group. Histologic examination revealed progressively deepening colonization of non-viable wound tissue, progressing to invasion of underlying viable tissue by PB day 4. With wound excision, SN, SNDC, and autografting were equally protective for the first two days, but only SN and SNDC extended this effect to the third PB day. In conclusion, SN and SNDC have a strong local anti-microbial effect on the burn wound when applied within 72 hours of the time of bacterial inoculation, but little effect if applied after the bacteria have invaded unburned vessels and viable tissue adjacent to the burn.

[Release of DNA from Pseudomonas aeruginosa in vitro during spontaneous growth and treatment with ciprofloxacin].

OBJECTIVE: To observe the DNA release from Pseudomonas aeruginosa (P. aeruginosa) during spontaneous growth and exposure to different concentrations of ciprofloxacin (Cipro) in vitro. METHODS: The P. aeruginosa 1244 strain (ATCC 27317) was selected because it was sensitive to Cipro in vitro. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of Cipro against this strain were determined, respectively. Different concentrations of Cipro were cultured with this strain at 37 degrees C for 4 h and 24 h. The samples of culture supernatant were filtered and electrophoresed in 1.8% agarose with SYBR Gold stain. Then the images of the gel sheets were photographed. RESULTS: The MIC and MBC of Cipro were 0.25 - 0.5 mg/L. The free bacterial DNA in 4 h culture samples with or without Cipro could not be detected by this method. The certain amount of free bacterial DNA molecules in 24 h culture samples without antibiotic appeared at the two zones whose molecular weights were more than 2000 bp and less than 100 bp. The large amount of free bacterial DNA molecules showed at three zones in 24 h culture samples with Cipro when its concentrations were much lower than its MIC. In terms of DNA molecular weight, the first two zones were above 2000 bp, and the third zone was below 100 bp. There was no detectable DNA release from bacteria in 24 h culture samples when Cipro was at or above its MIC. CONCLUSIONS: The certain amount of bacterial DNA were released from P. aeruginosa in the spontaneous growth. Different concentrations of Cipro had quite differential effects on the DNA release from P. aeruginosa in quantities and molecular weights in vitro.

Exogenous administration of Substance P enhances wound healing in a novel skin-injury model.

Soft tissue injury accounts for approximately 44% of all wounds in both the military and civilian populations. Following injury to soft tissue, Substance P (SP) and other neuropeptides are released by cutaneous neurons and modulate the function of immunocompetent and inflammatory cells, as well as epithelial and endothelial cells. The interaction between these components of the nervous system and multiple target cells affecting cutaneous repair is of increasing interest. In this report, we describe the effects of SP on wound repair in a novel, laser-induced, skin-wound model. Gross and histologic examination of laser-induced injury revealed that exogenously administered SP affects wound healing via neurite outgrowth, in addition to adhesion molecule and neurokinin-1 receptor involvement in vivo. All SP effects were decreased by pretreatment with Spantide II, an SP antagonist. The elucidation of SP-mediating mechanisms is crucial to firmly establishing the involvement and interaction of the peripheral nervous system and the immune system in cutaneous repair. Findings presented here suggest that SP participates in the complex network of mediators involved in cutaneous inflammation and wound healing.

External fixator pin tract infection model in the caprine (goat) tibia: a randomized, prospective, blinded study.

Six goats had 2 Schanz pins inserted in each tibia. Twenty-four pins were inoculated with saline or Staphylococcus aureus. Three investigators, blinded to the inoculum, evaluated 23 pins at 14 days. Clinical pin tract infections developed in all inoculated pins and in 5/12 uninoculated pins, Quantitative cultures demonstrated that infections were produced in 10/11 inoculated and in 0/12 uninoculated pins. Prediction of culture status by clinical criterion (P<.01, Fisher Exact Test) had 100% sensitivity and a 58% specificity. The prediction of infection in inoculated sites by culture criterion (P<.001, Fisher Exact Test) had a 91% sensitivity and 100% specificity. A reproducible long bone pin tract infection model was developed that produced clinically and microbiologically evident pin tract infections.

Survival benefit conferred by topical antimicrobial preparations in burn patients: a historical perspective.

BACKGROUND: Topical antimicrobial agents have proven efficacy in preventing life-threatening invasive burn wound infection. Under wartime or mass-casualty conditions, however, there may be an inadequate supply of these agents. This study aimed to identify those patients most likely to benefit therefrom. METHODS: Logistical regression analysis of data from the U.S. Army Burn Center was performed. Mortality data for the period immediately preceding the introduction of topical mafenide acetate (MA) (1950-1963) were compared with data for the subsequent period (1964-1968). During the second period, MA was routinely applied but treatment was otherwise similar. The mortality decrement attributed to MA was determined for various ages and burn sizes. RESULTS: For patients of combatant age (20-50 years), MA was associated with a greater than 10% reduction in mortality for those with burns of 40-79% of the total body surface area (TBSA). Only a minimal effect on mortality was noted for those patients with burns smaller than 40% or greater than 79%. CONCLUSIONS: When resources are limited, topical therapy (specifically, MA) is likely to confer the greatest survival benefit for combatants with burns of 40-79% TBSA.

Evaluation of renal cortical perfusion by noninvasive power Doppler ultrasound during vascular occlusion and reperfusion.

BACKGROUND: Urine output, a frequently used resuscitation end point, is presumed to represent renal cortical perfusion. However, no noninvasive method for direct measurement of renal perfusion exists. Power Doppler ultrasound (PDUS) is a method that reportedly is sensitive to low-velocity and microvascular blood flow and can depict it. This study aimed to develop a quantitative technique for PDUS image analysis, and to evaluate the ability of PDUS to quantify cortical perfusion during renal ischemia induced by vascular occlusion. METHODS: A method was developed to determine the mean gray-scale intensity of PDUS images from within the renal cortex (PDUS image intensity). This index was hypothesized to represent renal cortical microvascular blood flow. Renal cortical blood flow was determined using fluorescent microspheres in five swine. Renal artery flow was measured with an ultrasonic flow probe. Power Doppler ultrasound was performed at baseline; at 75%, 50%, and 25% of baseline renal artery flow; and during reperfusion. RESULTS: Subjectively, PDUS images showed decreases in image intensity corresponding to renal artery occlusion and increases after reperfusion. Cortical blood flow correlated well with renal artery flow (n = 25; r2 = 0.868) and with PDUS image intensity (n = 25; r2 = 0.844). CONCLUSION: Noninvasive power Doppler ultrasound image intensity correlated well with invasively measured renal cortical blood flow, and may be useful during resuscitation of injured and critically ill patients.

Predicting increased fluid requirements during the resuscitation of thermally injured patients.

BACKGROUND: We determined whether factors present soon after burn predict which patients will receive more than 4 mL/kg/% burn during the first 24 hours, and whether total fluid intake during the first 24 hours (VOL) contributes to in-hospital mortality (MORT). METHODS: We reviewed the records of patients admitted during 1987-97. The modified Brooke resuscitation formula was used. One hundred four patients met inclusion criteria: total body surface area burned (TBSA) > or = 20%; admission directly from the field; weight > 30 kg; no electric injury, mechanical trauma, or blood transfusions; and survival > or = 24 hours postburn. Eighty-nine records were complete. RESULTS: Mean TBSA was 43%, mean full-thickness burn size was 21%, mean age was 41 years, mean VOL was 4.9 mL/kg/% burn, and mean lactated Ringer's volume was 4.4 mL/kg/% burn; 53% had inhalation injury. MORT was 25.8%. Mean urine output was 0.77 mL/kg/h. By linear regression, VOL was associated with weight (negatively) and full-thickness burn size (r2 = 0.151). By logistic regression, receipt of over 4 mL/kg/% burn was predicted at admission by weight (negatively) and TBSA; by 24 hours postburn, mechanical ventilation replaced TBSA. With respect to MORT, logistic regression of admission factors yielded a model incorporating TBSA and an age function; by 24 hours postburn, the worst base deficit was added. CONCLUSION: Burn size and weight (negatively) were associated with greater VOL. However, a close linear relationship between burn size and VOL was not observed. Mechanical ventilation supplanted TBSA by 24 hours as a predictor of high VOL. Worst base deficit, TBSA, and an age function, but not VOL, were predictors of MORT.

Production of tumor necrosis factor-alpha, interleukin 1-beta, interleukin 2, and interleukin 6 by rat leukocyte subpopulations after exposure to substance P.

The interaction between components of the nervous system and multiple target cells in the cutaneous immune system has been receiving increasing attention. Recently, the involvement of neuropeptides has been demonstrated to play an important role in the inflammatory cascade. Neuropeptides such as Substance P are released by cutaneous neurons and modulate the function of immunocompetent and inflammatory cells as well as epithelial and endothelial cells. Substance P has been shown to function as a mediator for cell proliferation, cytokine production, and as an upregulator of various cell surface receptors. In this study, we show the effect of Substance P on the production of Tumor Necrosis Factor-alpha, Interleukin 1-beta, Interleukin 2, and Interleukin 6 by T-lymphocytes, macrophages and neutrophils. These data demonstrate that pathophysiological levels of Substance P induce production of cytokines in all three cell populations tested. Interestingly, T-cells demonstrated the highest percentage of cells expressing all four cytokines. In contrast, macrophages and neutrophils produced the highest absolute levels of cytokines. The elucidation of mediating mechanisms of Substance P activation of leukocytes is crucial to the understanding of the cutaneous inflammatory cascade and involvement of the peripheral nervous system on the immune system. These findings suggest that Substance P participates in the complex network of mediators that regulate cutaneous inflammation and potentially the rate of wound healing.

Antibodies against human cell receptors, CD36, CD41a, and CD62P crossreact with porcine platelets.

BACKGROUND: A limitation in platelet study has been the availability of platelet function-specific membrane receptor antibodies for use in the various animal species that are currently used in the study of hemostasis and other phenomena. METHODS: Platelets were isolated from human and porcine blood. Resting and activated platelets were incubated with antibodies against the human cell surface receptors CD36 (clone CB38), CD41a (clone HIP8), CD62P (clone AK4), and CD63 (clone H5C6). Antibody titration and ligand blocking studies also were performed. RESULTS: Binding of anti-CD41a and anti-CD62P were similar for human and porcine platelets in percentage of platelets labeled and in number of receptors per cell. Binding of anti-CD36 was similar between species, with fewer receptors present in porcine cells. Anti-CD63 and anti-CD107a did not bind specifically to porcine platelets. CONCLUSION: The anti-CD36, anti-CD41a, and anti-CD62P antibodies studied crossreact with porcine platelets and will be useful in the investigation of platelet function in porcine models.

Advanced hemostatic dressing development program: animal model selection criteria and results of a study of nine hemostatic dressings in a model of severe large venous hemorrhage and hepatic injury in Swine.

BACKGROUND: An advanced hemostatic dressing is needed to augment current methods for the control of life-threatening hemorrhage. A systematic approach to the study of dressings is described. We studied the effects of nine hemostatic dressings on blood loss using a model of severe venous hemorrhage and hepatic injury in swine. METHODS: Swine were treated using one of nine hemostatic dressings. Dressings used the following primary active ingredients: microfibrillar collagen, oxidized cellulose, thrombin, fibrinogen, propyl gallate, aluminum sulfate, and fully acetylated poly-N-acetyl glucosamine. Standardized liver injuries were induced, dressings were applied, and resuscitation was initiated. Blood loss, hemostasis, and 60-minute survival were quantified. RESULTS: The American Red Cross hemostatic dressing (fibrinogen and thrombin) reduced (p < 0.01) posttreatment blood loss (366 mL; 95% confidence interval, 175-762 mL) and increased (p < 0.05) the percentage of animals in which hemostasis was attained (73%), compared with gauze controls (2,973 mL; 95% confidence interval, 1,414-6,102 mL and 0%, respectively). No other dressing was effective. The number of vessels lacerated was positively related to pretreatment blood loss and negatively related to hemostasis. CONCLUSION: The hemorrhage model allowed differentiation among topical hemostatic agents for severe hemorrhage. The American Red Cross hemostatic dressing was effective and warrants further development.

Burn center management of necrotizing fasciitis.

Necrotizing fasciitis is a rapidly progressive soft-tissue infection associated with significant morbidity and mortality. Necrotizing fasciitis is similar to invasive burn wound infection in that diagnosis requires histologic examination of affected tissue and treatment requires aggressive surgical debridement followed by skin autograft. Transfer to a burn center facilitates the management of necrotizing fasciitis, where requisite surgical and nursing expertise is available. We reviewed the experience of one burn center in the management of necrotizing fasciitis over a 5-year period. Ten patients were transferred to the burn center from other medical facilities for care, arriving a mean of 8.9 days after initial hospital admission. The diagnosis was made by a surgical service or consultation before transfer in all cases; initial admission to a medical rather than a surgical service delayed surgery in five cases. All patients had surgical debridement before transfer but required a mean of 5.1 additional operations at the burn center. Although the mean extent of involvement was 14.8% body surface area, the mean length of burn center stay was 34.9 days. Complications were frequent, including pulmonary failure requiring mechanical ventilation (n = 6), renal insufficiency or failure (n = 5), hypotension requiring pressers (n = 4), deep venous thrombosis (n = 3), and pulmonary emboli (n = 1). Overall mortality was 2 of 10 patients (20%). Both fatalities were associated with delay in initial surgical procedure and in transfer to the burn center. The similarity of necrotizing fasciitis and invasive burn wound infection makes the burn center the ideal setting for the treatment of this disease. We advocate the addition of necrotizing fasciitis to the list of conditions currently recognized by the American Burn Association as appropriate for burn center transfer and care.

Optical monitoring and treatment of potentially lethal wound infections in vivo.

We report on the use of optical techniques to monitor and treat Pseudomonas aeruginosa wound infections in mice. Bioluminescent bacteria transduced with a plasmid containing a bacterial lux gene operon allow the infection in excisional mouse wounds to be imaged by use of a sensitive charge-coupled device camera. Photodynamic therapy (PDT) targeted bacteria, by use of a polycationic photosensitizer conjugate, which is designed to penetrate the gram-negative cell wall and was topically applied to the wound and was followed by red-light illumination. There was a rapid light dose-dependent loss of luminescence, as measured by image analysis, in the wounds treated with conjugate and light, a loss that was not seen in untreated wounds, wounds treated with light alone, or wounds treated with conjugate alone. P. aeruginosa was invasive in our mouse model, and all 3 groups of control mice died within 5 days; in contrast, 90% of PDT-treated mice survived. PDT-treated wounds healed significantly faster than did silver nitrate-treated wounds, and this was not due to either inhibition of healing by silver nitrate or stimulation of healing by PDT.

Effect of a chitosan-based hemostatic dressing on blood loss and survival in a model of severe venous hemorrhage and hepatic injury in swine.

BACKGROUND: Hemorrhage is a leading cause of death from trauma. An advanced hemostatic dressing could augment available hemostatic methods. We studied the effects of a new chitosan dressing on blood loss, survival, and fluid use after severe hepatic injury in swine. METHODS: Swine received chitosan dressings or gauze sponges. Standardized, severe liver injuries were induced. After 30 seconds, dressings were applied and resuscitation initiated. Blood loss, hemostasis, resuscitation volume, and 60-minute survival were quantified. RESULTS: Posttreatment blood loss was reduced ( p< 0.01) in the chitosan group (264 mL; 95% confidence interval [CI], 82-852 mL) compared with the gauze group (2,879 mL; 95% CI, 788-10,513 mL). Fluid use was reduced ( p= 0.03) in the chitosan group (1,793 mL; 95% CI, 749-4,291) compared with the gauze group (6,614 mL; 95% CI, 2,519-17,363 mL). Survival was seven of eight and two of even in the chitosan and gauze groups ( p= 0.04), respectively. Hemostasis was improved in the chitosan group ( p= 0.03). CONCLUSION: A chitosan dressing reduced hemorrhage and improved survival after severe liver injury in swine. Further studies are warranted.

Integra as a dermal replacement in a meshed composite skin graft in a rat model: a one-step operative procedure.

BACKGROUND: Current use of Integra, the collagen-based dermal analogue, requires a two-step grafting procedure to achieve wound closure with an "ultrathin" autograft. METHODS: A one-step operative procedure of meshed composite skin graft (MCSG) using Integra as a dermal template for a meshed split thickness autograft was developed in rats. The silicon layer of Integra was removed, the resulting dermal analogue was meshed (1:1.5), expanded, and placed on excised full thickness wound and covered with a meshed (1:1.5 or 1:6) split thickness autograft. Grafted wounds were dressed with BioBrane, Vaseline gauze, silver-impregnated nylon, or silver-nylon and direct current (SNDC). At scheduled intervals up to 3 months postgrafting, wounds were examined for epithelialization, collagen deposition and fibrosis, hair growth, and contraction. The results of wound closure and healing following the one-step procedure were compared with the outcome of the two-step grafting procedure where application of meshed Integra (step one) was followed in 14 days by removal of the silicon layer and application of the meshed autograft (step two). RESULTS: The one-step procedure applied to meshed autograft/Integra (1:1.5/1:1.5) composite graft accelerated wound closure by 6-19 days when compared with the two-step procedure. At 3 months postgrafting, the contraction of the healed wound dressed with SNDC, BioBrane, or Vaseline gauze was reduced by 13-16% following the one-step procedure compared with the two-step procedure (p < 0.05). The one-step procedure allowed the expansion of the autograft layer to 1:6 while achieving wound healing results similar to grafting with 1:1.5 meshed autograft layer using the two-step grafting procedure. CONCLUSION: Single-step application of meshed, thin, split thickness autograft over meshed Integra-derived dermal substitute allows more rapid wound closure with less contraction and more efficient use of graft donor skin than can be obtained with the commonly used two-step grafting procedure.