Timothy D. Light

Long-term outcomes of patients with necrotizing fasciitis.

Context:Necrotizing fasciitis is an aggressive infection affecting the skin and soft tissue. It has a very high acute mortality. The long-term survival and cause of death of patients who survive an index hospitalization for necrotizing fasciitis are not known. Objective:To define the long-term survival of patients who survive an index admission for necrotizing fasciitis. We hypothesize that survivors will have a shorter life span than population controls. Design:Long-term follow-up of a registry of patients from 1989 to 2006 who survived a hospitalization for necrotizing fasciitis. Last date of follow-up was January 1, 2008. Settings:A university-based Burn and Trauma Center. Patients:A prospective registry of patients with necrotizing fasciitis has been collected from 1989 to 2006. This registry was linked to data from the Department of Health, Department of Motor Vehicles, and the University Hospital Medical Records Department in January 2008 to obtain follow-up and vital status data. Intervention:None. Main Outcome Measures:Date and cause of death were abstracted from death certificates. Date of last live follow-up was determined from the medical record and by the last drivers license renewal. The death rate of the cohort was standardized for age and sex against 2005 statewide mortality rates. Cause of death was collated into infectious and noninfectious and compared with the statewide causes of death. Statistical analysis included standardized mortality rates, Kaplan-Meier survival curves, and Aalens additive hazard model. Results:Three hundred forty-five patients of the 377 in the registry survived at least 30 days and were analyzed. Average age at presentation was 49 years (range, 1–86; median, 49). Patients were followed up an average of 3.3 years (range, 0.0–15.7; median, 2.4). Eighty-seven of these patients died (25%). Median survival was 10.0 years (95% confidence interval: 7.25–13.11). There was a trend toward higher mortality in women. Twelve of the 87 deaths were due to infectious causes. Using three different statistical analytic techniques, there was a statistically significant increase in the long-term death rate when compared with population-based controls. Infectious causes of death were statistically higher than controls as well. Conclusions:Patients who survive an episode of necrotizing fasciitis are at continued risk for premature death; many of these deaths were due to infectious causes such as pneumonia, cholecystitis, urinary tract infections, and sepsis. These patients should be counseled, followed, and immunized to minimize chances of death. Modification of other risk factors for death such as obesity, diabetes, smoking, and atherosclerotic disease should also be undertaken. The sex difference in long-term survival is intriguing and needs to be addressed in further studies.

Risk Factors for Acquiring Vancomycin-Resistant Enterococcus and Methicillin-Resistant Staphylococcus aureus on a Burn Surgery Step-Down Unit

The incidence of hospital-associated infections secondary to methicillin-resistant Staphylococcus aureus (MRSA) and those caused by vancomycin-resistant enterococci (VRE) continue to increase, despite the publication of evidence-based guidelines on infection control. We sought to determine modifiable risks factors for acquisition of MRSA or VRE or both on a burn trauma unit (BTU). We performed a retrospective single-center–matched control study. Our study group comprised 94 patients who acquired MRSA or VRE or both while on the BTU from January 1, 2001 to December 31, 2005. The case-patients were matched 1:1 to control-patients based on the time the cases were exposed to the BTU before they became colonized or infected. Logistic regression was used to analyze the relationship of demographic, procedure, and antimicrobial exposure variables to acquisition of MRSA or VRE. Acquisition of MRSA or VRE was related to patient factors, antimicrobial exposure, and device use. Younger age and prior vancomycin treatment while on the BTU were independently associated with MRSA acquisition. The presence of a Foley catheter was related to VRE acquisition. Sixteen study patients (17.0%) who became colonized on the BTU subsequently acquired 17 infections: six patients had MRSA bloodstream infections, nine had MRSA burn wound infections, and two had VRE urinary tract infections. Younger age, exposure to vancomycin, or Foley catheters were associated with increased risk of acquiring MRSA or VRE. Protocols or algorithms that help physicians remember to assess the necessity of antimicrobial agents and devices may help limit the duration of exposure to these risk factors, which may enhance infection prevention efforts. Future studies need to explore the effect of these variables on cross-transmission and their impact predominately in a burn unit.

Morphological parameters for assessment of burn severity in an acute burn injury rat model

Determination of burn severity (i.e. burn depth) is important for effective medical management and treatment. Using a recently described acute burn model, we studied various morphological parameters to detect burn severity. Anaesthetized Sprague–Dawley rats received burns of various severity (0‐ to14‐s contact time) followed by standard resuscitation using intravenous fluids. Biopsies were taken from each site after 5 h, tissues fixed in 10% neutral‐buffered formalin, processed and stained with haematoxylin and eosin. Superficial burn changes in the epidermis included early keratinocyte swelling progressing to epidermal thinning and nuclear elongation in deeper burns. Subepidermal vesicle formation generally decreased with deeper burns and typically contained grey foamy fluid. Dermal burns were typified by hyalinized collagen and a lack of detectable individual collagen fibres on a background of grey to pale eosinophilic seroproteinaceous fluid. Intact vascular structures were identified principally deep to the burn area in the collagen. Follicle cell injury was identified by cytoplasmic clearing/swelling and nuclear pyknosis, and these follicular changes were often the deepest evidence of burn injury seen for each time point. Histological scores (epidermal changes) or dermal parameter depths (dermal changes) were regressed on burn contact time. Collagen alteration (r2 = 0.91) correlated best to burn severity followed by vascular patency (r2 = 0.82), epidermal changes (r2 = 0.76), subepidermal vesicle formation (r2 = 0.74) and follicular cell injury was useful in all but deep burns. This study confirms key morphological parameters can be an important tool for the detection of burn severity in this acute burn model.

The Effect of Burn Center and Burn Center Volume on the Mortality of Burned Adults-An Analysis of the Data in the National Burn Repository

Regional variations of care, and improved outcomes with larger volumes, have been well described in the medical and surgical literature for a variety of conditions including heart surgery, vascular surgery, and orthopedic surgery. Burn care has not been recently subjected to such an analysis. The National Burn Repository (NBR) contains de-identified patient and burn center data to allow this analysis. The NBR was queried for adult burn patients admitted for an acute thermal burn injury. A multivariable regression analysis to identify risk of death was performed incorporating patient characteristics, de-identified burn center, and burn center volume. Patient characteristics such as age, size of burn, mechanism of burn, inhalation injury, race, and sex determine mortality. There is also a statistically significant difference in death rates when individual, de-identified centers are compared. This difference in care persists even when accounting for burn center volume. Analysis of registries like the NBR, insurance claims databases, and statewide hospital discharge databases may help identify opportunities to improve burn care. According to this analysis of data available in the NBR, burn mortality depends not only on patient characteristics but also where the patient is treated. Mortality does not linearly improve with burn center volume and plateaus with increasing burn center size. The optimal burn center size is a complicated and contentious question. Future discussions about burn center size and density should incorporate not only mortality but also the region’s ability to absorb surges in volume, and the optimal “staffing” ratios for the multidisciplinary aspects of burn care.

The evolution of resource utilization in regional burn centers.

Regional burn centers provide unique multidisciplinary care that has been associated with dramatically improved outcomes for burn victims. Patients with complex skin and soft tissue injuries are increasingly admitted to these centers for definitive care. This study was designed to assess current trends in burn center resource utilization. Members of the Multicenter Trials Group of American Burn Association were invited to participate in this retrospective review of all patients admitted to their respective regional burn centers during a 10-year period. Collected data included admission diagnosis, demographics, length of stay (LOS), hospital charges, and mortality. Five regional academic burn centers participated. They collectively admitted 18,246 patients during the study period, of whom 15,219 (83.4%) had a primary burn diagnosis and 3027 (16.6%) were patients with nonburn diagnoses. During this period, annual admissions for the five centers increased by 34.7%, ranging from 19 to 83% for individual centers. Simultaneously, mean burn size decreased from 12.3 to 8.8% TBSA. From 1998 to 2006, admissions for nonburn diagnoses increased by 244.9%, whereas burn admissions increased by 31.1%. Although mean LOS was reduced by >25%, total charges for all patients increased by 37.7% after adjustment for inflation. Nonburn patients had significantly higher mean age, longer LOS, greater mortality, and higher daily charges. This review of admissions to five academic burn centers reveals that these centers are treating more patients with smaller burns and an increasing number of complex nonburn conditions. Nonburn patients represent an older and more debilitated population that consumes disproportionately more resources than burn patients. These data show a dramatic shift in burn center resource utilization and the concurrent evolution of regional burn centers into centers for the care of complex wounds.

The impact of opioid administration on resuscitation volumes in thermally injured patients.

Administration of resuscitation volumes far beyond the estimates established by burn-body weight resuscitation formulas has been well documented. The reasons behind this increase are not clear. We sought to determine if our resuscitation volumes had increased and, if so, what factors were related to their increase. A retrospective chart review identified 154 patients admitted with burns greater than 20% of their BSA during the years of 1975–1976 (period 1), 1990–1991 (period 2), and 2006–2007 (period 3). Charts were reviewed for total fluids (crystalloid, colloid, and blood products) and opioids given before admission, during the first 8 hours of treatment, the next 16 hours of treatment, and the following 24 hours of treatment. Opioids were converted to opioid equivalents (OE). Multiple regression analysis was performed to determine the effects of variables of interest and control for confounders. Significance was assumed at the P < .05 level. Resuscitation fluid volumes increased significantly among adults from 3.97 ml/kg/%BSA during the first period to 6.40 ml/kg/%BSA during the third period (P < .01). The same trend in children <30 kg was not seen (P = .72). Fluid administered during the first 24 hours was significantly associated with age, BSA, intubation, latter two study periods, and opioid administration. Fluid administration was consistently associated with opioid administration at all measured time points. At 24 hours postburn, patients who received 2 to 4 OE/kg required an average of additional 3,650 ± 1,704 ml of fluid, those receiving 4 to 6 OE/kg had required an average of 25,154 ± 4,386 ml, and those who received >6 OE kg had required an average of 32,969 ± 3,982 ml. In this single center retrospective study, we have shown a statistically significant increase in resuscitation fluids (from 1975 to 2007) and an association of resuscitation volumes with opioids. Opioids have been shown to increase resuscitation volumes in critically ill patients through both central and peripheral effects on the cardiovascular system. Because increased fluid resuscitation has been associated with adverse consequences in other studies, further research on alternative pain control strategies in thermally injured patients is warranted.

The Efficacy of Hair and Urine Toxicology Screening on the Detection of Child Abuse by Burning

Abuse by burning is estimated to occur in 1 to 25% of children admitted with burn injuries annually. Hair and urine toxicology for illicit drug exposure may provide additional confirmatory evidence for abuse. To determine the impact of hair and urine toxicology on the identification of child abuse, we performed a retrospective chart review of all pediatric patients admitted to our burn unit. The medical records of 263 children aged 0 to 16 years of age who were admitted to our burn unit from January 2002 to December 2007 were reviewed. Sixty-five children had suspected abuse. Of those with suspected abuse, 33 were confirmed by the Department of Health and Human Services and comprised the study group. Each of the 33 cases was randomly matched to three pediatric (0–16 years of age) control patients (99). The average annual incidence of abuse in pediatric burn patients was 13.7 ± 8.4% of total annual pediatric admissions (range, 0–25.6%). Age younger than 5 years, hot tap water cause, bilateral, and posterior location of injury were significantly associated with nonaccidental burn injury on multivariate analysis. Thirteen (39.4%) abused children had positive ancillary tests. These included four (16%) skeletal surveys positive for fractures and 10 (45%) hair samples positive for drugs of abuse (one patient had a fracture and a positive hair screen). In three (9.1%) patients who were not initially suspected of abuse but later confirmed, positive hair test for illicit drugs was the only indicator of abuse. Nonaccidental injury can be difficult to confirm. Although inconsistent injury history and burn injury pattern remain central to the diagnosis of abuse by burning, hair and urine toxicology offers a further means to facilitate confirmation of abuse.

Autopsy after traumatic death--a shifting paradigm.

OBJECTIVE The role of autopsy in evaluating missed injury after traumatic death is well established and discussed in the literature. The frequency of incidental findings in trauma patients has not been reported. We believe that incidental findings are under recognized and reported by trauma surgeons. PATIENTS AND METHODS This prospective, descriptive, cohort study was conducted at a Level 1 trauma center in a rural state. Four hundred ninety-six deaths over a 4-y period were identified from the trauma registry. Two hundred four complete autopsies were available for review. One thousand eighteen traumatic diagnoses were identified from 204 autopsies and corresponding medical records by trauma surgeons blinded to patient identity. The surgeons recorded missed diagnoses, incidental diagnoses identified at autopsy, and diagnoses known at the time of death confirmed by autopsy. RESULTS The surgeons had a κ-score of 0.82-0.84. Forty-two patients (21% of patients) had 68 severe missed injuries; 67 patients (33% of patients) had 94 minor missed injuries. Twenty-eight patients (14%) had significant incidental findings including premature atherosclerosis, multiple endocrine neoplasia, tuberculosis, and others. CONCLUSIONS The autopsy after traumatic death is more than a mechanism of quality control and teaching. A high proportion of patients will have incidental findings important to family members, and have public health importance. Systems need to be developed to review autopsy results with attention to identifying and communicating incidental findings. Given the incidence of significant missed injuries and incidental findings, the autopsy continues to have an important role in health care.

Effectiveness of universal screening for vancomycin-resistant enterococcus and methicillin-resistant Staphylococcus aureus on admission to a burn-trauma step-down unit.

Vancomycin-resistant enterococcus (VRE) and methicillin-resistant Staphylococcus aureus (MRSA) are significant healthcare-associated pathogens. We sought to identify factors that could be used to predict which patients carry or are infected with VRE or MRSA on admission so that we could obtain cultures selectively from high-risk patients on our burn-trauma unit. We conducted a case–control study of patients admitted to our burn-trauma unit from September 2000 to March 2005 who were colonized or infected with either VRE or MRSA (cases) and patients who were not colonized or infected with one of these organisms (controls). We used logistic regression to construct a model that we subsequently validated based on data collected prospectively from patients admitted from September 2006 to August 2007. In the case–control study, colonization or infection with MRSA or VRE on admission were independently associated with the total days of antimicrobial treatment, age, prior hospitalization, prior operations, and admitting diagnosis (admission for a burn injury was protective). In the cohort study, a prior hospitalization with a length of stay ≥7 days and operations within the past 6 months were significantly associated with colonization or infection on admission. The latter model was 59.3% sensitive. If, we used this model to identify which patients should be cultured on admission, we would have missed 24 (39.3%) of the colonized or infected patients. These patients would not have been placed in isolation (434 missed isolation days, 71.0%) and may have been the source of transmission to other patients. Our model lacked the sensitivity to identify patients colonized or infected with VRE or MRSA. We recommend that units, which care for patients who are at high risk of hospital-acquired infection and having prevalence and transmission rates of VRE or MRSA similar to those in our study, screen all patients for these organisms on admission to the unit.

Apoptosis is differentially regulated by burn severity and dermal location.

BACKGROUND The cellular processes that contribute to cell death in burns are poorly understood. This study evaluated the distribution and extent of apoptosis in an established rat model of acute dermal burn injury. MATERIALS AND METHODS A branding iron (100 degrees C) was applied to the depilated dorsum of seven rats, creating burn contact times of 1-8, 10, 12, and 14 s. Biopsies were collected and immunohistochemistry performed for apoptosis and cell injury/necrosis by detection of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and high-mobility group box 1 (HMGB1), respectively. The slides were scored by evaluating staining in superficial, middle, and deep dermal fields. Within these, basal keratinocytes of the epidermis, mesenchymal cells, adnexal epithelia, and vasculature wall cells were morphometrically analyzed for stain detection of selected markers. RESULTS TUNEL staining had an inverse relationship with contact time in most fields except in deep dermal mesenchymal cells where it was increased. HMGB1 nuclear staining was significantly decreased with progressive contact time consistent with transition to cell injury/necrosis. CONCLUSIONS This study is the first to demonstrate that apoptosis rate is dependent on dermal location, cell type, and severity of thermal injury. Furthermore, this work suggests that for most dermal locations increased thermal injury corresponds with decreased apoptosis and increased cell injury/necrosis. Together, these findings indicate that many parameters can regulate apoptosis in burn wounds, and these results will be critical to understanding burn pathogenesis and assessing future therapies.