Jenny A. Ziembicki

Evolving role of endovascular techniques for traumatic vascular injury: a changing landscape?

Background: Endovascular management of blunt aortic injury has dramatically reduced the morbidity and mortality associated with this specific injury. There remains a paucity of evidence quantifying the beneficial effects associated with endovascular (ENDO) techniques for other vascular injury types and little information regarding the impact ENDO techniques have had on the management of traumatic vascular injuries over time. Methods: We performed a retrospective analysis of data from the National Trauma Data Bank over 2002 to 2006 and 2008 time periods (NTDB 7.2 and RDS 2008). Injured patients undergoing any arterial vascular repair procedure using ENDO or standard open techniques were determined using ICD-9-CM procedure codes. Abbreviated Injury codes were used to select patients who suffered subclavian, carotid, or thoracic aortic injury. Logistic regression was used to determine whether EARLY ENDO procedures (first 24 hours after injury) were independently associated with a lower risk of mortality. Results: The percentage of ENDO procedures significantly increased over time irrespective of mechanism of injury. When aortic (thoracic), subclavian, and carotid arterial injuries were analyzed, a significant decrease in mortality over time was found. The percentage of ENDO procedures for all arterial injury subtypes significantly increased in the RECENT (2008) period. Seventy-five percentage of ENDO procedures occurred early (initial 24 hours) with 20% of those patients being hypotensive upon arrival (systolic blood pressure <90 mm Hg). For patients who had vascular procedures in the RECENT period, regression analysis revealed that early ENDO procedures were independently associated with a 35% reduction in mortality risk (odds ratio, 0.65; 95% confidence interval, 0.5–0.8) after controlling for major confounders including mechanism of injury and presence of hypotension on arrival. Conclusion: ENDO procedures for arterial injury have increased over time while mortality for arterial injury subtypes has significantly decreased. Early ENDO procedures are common and are independently associated with a lower risk of mortality. These results suggest outcomes after vascular injury may benefit from ENDO expertise and that ENDO techniques should be incorporated into the early treatment algorithm of trauma patients with vascular injury, particularly those that require difficult operative exposure. Level of Evidence: III

Characterization of sex dimorphism following severe thermal injury.

Sex-based outcome differences have been previously studied after thermal injury, with a higher risk of mortality being demonstrated in women. This is opposite to what has been found after traumatic injury. Little is known about the mechanisms and time course of these sex outcome differences after burn injury. A secondary analysis was performed using data from a prospective observational study designed to characterize the genetic and inflammatory response after significant thermal injury (2003–2010). Clinical outcomes were compared across sex (female vs male), and the independent risks associated with sex were determined using logistic regression analysis after controlling for important confounders. Stratified analysis across age and burn severity was performed, whereas Cox hazard survival curves were constructed to determine the time course of any sex differences found. During the time period of the study, 548 patients met inclusion criteria for the cohort study. Men and women were found to be similar in age, TBSA%, inhalation injury, and Acute Physiology and Chronic Health score. Regression analysis revealed that female sex was independently associated with over a 2-fold higher mortality after controlling for important confounders (odds ratio, 2.2; P = .049; 95% confidence interval, 1.01–4.8). The higher independent mortality risk for women was exaggerated and remained significant only in pediatric patients and demonstrated a dose–response relationship with increasing burn size (%TBSA). Survival analysis demonstrated early separation of female and male curves, and a greater independent risk of multiple organ failure was demonstrated in the pediatric cohort. The current results suggest that sex-based outcome differences may be different after thermal injury compared with traumatic injury and that the sex dimorphism may be exaggerated in patients with higher burn size and in those in the pediatric age group, with female sex being associated with poor outcome. These sex-based mortality differences occur early and may be a result of a higher risk of organ failure and early differences in the inflammatory response after burn injury. Further investigation is required to thoroughly characterize the mechanisms responsible for these divergent outcomes.

Risk Factors for Hypothermia in EMS-treated Burn Patients

Abstract Objective. Hypothermia has been associated with increased mortality in burn patients. We sought to characterize the body temperature of burn patients transported directly to a burn center by emergency medical services (EMS) personnel and identify the factors independently associated with hypothermia. Methods. We utilized prospective data collected by a statewide trauma registry to carry out a nested case-control study of burn patients transported by EMS directly to an accredited burn center between 2000 and 2011. Temperature at hospital admission ≤36.5°C was defined as hypothermia. We utilized registry data abstracted from prehospital care reports and hospital records in building a multivariable regression model to identify the factors associated with hypothermia. Results. Forty-two percent of the sample was hypothermic. Burns of 20–39% total body surface area (TBSA) (OR 1.44; 1.17–1.79) and ≥40% TBSA (OR 2.39; 1.57–3.64) were associated with hypothermia. Hypothermia was also associated with age > 60 (OR 1.50; 1.30–1.74), polytrauma (OR 1.58; 1.19–2.09), prehospital Glasgow Coma Scale <8 (OR 2.01; 1.46–2.78), and extrication (OR 1.49; 1.30–1.71). Hypothermia was also more common in the winter months (OR 1.54; 1.33–1.79) and less prevalent in patients weighing over 90 kg (OR 0.63; 0.46–0.88). Conclusions. A substantial proportion of burn patients demonstrate hypothermia at hospital arrival. Risk factors for hypothermia are readily identifiable by prehospital providers. Maintenance of normothermia should be stressed during prehospital care.

Admission temperature and survival in patients admitted to burn centers.

It is commonly believed that hypothermia occurring during burn resuscitation is associated with poor outcome, but there is little direct supporting evidence. The authors conducted an analysis of a statewide trauma registry to determine whether hypothermia (T ⩽36.5°C) was associated with mortality when controlling for clinical confounders. They included all patients treated at an accredited burn center from 2000 to 2011 where the trauma registrar recorded the primary injury type as a burn. They excluded records with missing data and nonphysiologic temperature (<26°C or >42°C). The primary exposure of interest was hypothermia. The authors constructed a hierarchical, multivariable logistic regression model to examine the effect of hypothermia on survival, controlling for potentially confounding variables. Predictors of mortality are presented as odds ratio (95% confidence interval). Primary burn injury was coded 17,098 times during the study period. Of these, 3809 were not treated at a burn center and 1192 were excluded for missing data. Admission hypothermia was independently associated with mortality (1.91 [1.58–2.29]) when adjusting for age, sex, total second- and third-degree burn surface area (TBSA), comorbid conditions, injury severity score, direct transport vs referral, method of temperature measurement, year, and the hospital providing care. Increasing age, female sex, TBSA >40%, presence of multiple comorbid conditions, and increasing injury severity score were associated with mortality. Other variables in the model were not independently associated with outcome. There was a weak correlation between TBSA and admission temperature (r = .18). Hypothermia at hospital admission is independently associated with mortality in burn patients when controlling for clinical confounders. Future studies should address potential causes underlying this observation.

Radiographic assessment of ground-level falls in elderly patients: Is the “PAN-SCAN” overdoing it?

INTRODUCTION Routine, whole-body computed tomography imaging (PAN-SCAN) has been shown to identify unexpected injuries and alter the management of patients presenting with blunt trauma. We sought to characterize the changes in practice over time and the utility of PAN-SCAN imaging in elderly patients who fall and require admission to a trauma center. METHODS We performed a retrospective analysis by using data derived from a Pennsylvania state-wide trauma registry (2007-2010). All hemodynamically stable patients (>65 years) who had a ground-level fall and were admitted for >24 hours were selected. Patients who underwent a combination of all three scans within 2 hours of arrival were considered to have underwent PAN-SCAN imaging. Clinical outcomes were compared across PAN-SCAN patients relative to less diagnostic imaging. Regression analysis was used to determine whether PAN-SCAN imaging was an independent determinate of mortality and resource use. RESULTS Over the period of study, 13,043 patients met inclusion criteria. The annual rate of PAN-SCAN imaging after ground-level falls increased over time. After we controlled for important confounders, PAN-SCAN imaging was not associated with mortality (odds ratio 0.97, P = .74, 95% confidence interval 0.80-1.18). Despite greater injury severity, PAN-SCAN imaging was independently associated with significantly lesser intensive care unit requirements, step-down days, and a lesser overall duration of stay. CONCLUSION PAN-SCAN imaging has become more common over time in elderly patients having a ground-level fall. Although PAN-SCAN imaging during the initial trauma evaluation was not associated with an independent decrease in the risk of mortality, it was independently associated with lesser hospital resource use. These data suggest that whole-body computed tomography imaging may benefit trauma center resource use for patients with ground-level falls.

Second-degree burns with six etiologies treated with autologous noncultured cell-spray grafting.

Partial and deep partial-thickness burn wounds present a difficult diagnosis and prognosis that makes the planning for a conservative treatment versus mesh grafting problematic. A non-invasive treatment strategy avoiding mesh grafting is often chosen by practitioners based on their clinical and empirical evidence. However, a delayed re-epithelialization after conservative treatment may extend the patients hospitalization period, increase the risk of infection, and lead to poor functional and aesthetic outcome. Early spray grafting, using non-cultured autologous cells, is under discussion for partial and deep partial-thickness wounds to accelerate the re-epithelialization process, reducing the healing time in the hospital, and minimizing complications. To address planning for future clinical studies on this technology, suitable indications will be interesting. We present case information on severe second-degree injuries after gas, chemical, electrical, gasoline, hot water, and tar scalding burns showing one patient per indication. The treatment results with autologous non-cultured cells, support rapid, uncomplicated re-epithelialization with aesthetically and functionally satisfying outcomes. Hospital stays averaged 7.6±1.6 days. Early autologous cell-spray grafting does not preclude or prevent simultaneous or subsequent traditional mesh autografting when indicated on defined areas of full-thickness injury.

Calculations for reproducible autologous skin cell-spray grafting

Non-cultured, autologous cell-spray grafting is an alternative to mesh grafting for larger partial- and deep partial-thickness burn wounds. The treatment uses a suspension of isolated cells, from a patients donor site skin tissue, and cell-spray deposition onto the wound that facilitates re-epithelialization. Existing protocols for therapeutic autologous skin cell isolation and cell-spray grafting have defined the donor site area to treatment area ratio of 1:80, substantially exceeding the coverage of conventional mesh grafting. However, ratios of 1:100 are possible by maximizing the wound treatment area with harvested cells from a given donor site skin tissue according to a given burn area. Although cell isolation methods are very well described in the literature, a rational approach addressing critical aspects of these techniques are of interest in planning clinical study protocols. We considered in an experimental study the cell yield as a function of the donor site skin tissue, the cell density for spray grafting, the liquid spray volume, the sprayed distribution area, and the percentage of surface coverage. The experimental data was then used for the development of constants and mathematical equations to give a rationale for the cell isolation and cell-spray grafting processes and in planning for clinical studies.

In vitro keratinocyte expansion for cell transplantation therapy is associated with differentiation and loss of basal layer derived progenitor population

An alternative approach for traditional clinical mesh grafting in burn wound treatment is the use of expanded autologous keratinocytes in suspension or sheets that are cultured over 2-4 weeks in a remote service facility. While a wound reepithelialization has been described, the functional and aesthetic outcome is under debate. Cell isolation from split-skin donor tissue aims to preserve the valuable stem cell progenitors from the basal epidermal layer and to provide patients with a rapid wound reepithelialization and a satisfying outcome. While the presence of epidermal progenitors in the cell graft is thought to enable an improved epidermal surface post reepithelialization, we investigated a feasible clinical approach involving cultured versus noncultured epidermal cells comparing the α6int(high)/K15(high)/FSC(low)/SSC(low) and α6int(high)/K5(high)/FSC(low)/SSC(low) keratinocyte progenitor subpopulations before and after in vitro culture process. Our results show a significant increase of cell size during in vitro passaging and a decrease of progenitor markers linked to a gradual differentiation. A provision of the regenerative epidermal progenitors, isolated from the split-skin biopsy and applied directly onto the wound in an on-site setting of isolation and cell spray grafting in the operation room, could be of interest when choosing options for skin wound care with autologous cells.

Effects of wound dressings on cultured primary keratinocytes

Autologous cell-spray grafting of non-cultured epidermal cells is an innovative approach for the treatment of severe second-degree burns. After treatment, wounds are covered with dressings that are widely used in wound care management; however, little is known about the effects of wound dressings on individually isolated cells. The sprayed cells have to actively attach, spread, proliferate, and migrate in the wound for successful re-epithelialization, during the healing process. It is expected that exposure to wound dressing material might interfere with cell survival, attachment, and expansion. Two experiments were performed to determine whether some dressing materials have a negative impact during the early phases of wound healing. In one experiment, freshly isolated cells were seeded and cultured for one week in combination with eight different wound dressings used during burn care. Cells, which were seeded and cultured with samples of Adaptic(®), Xeroform(®), EZ Derm(®), and Mepilex(®) did not attach, nor did they survive during the first week. Mepitel(®), N-Terface(®), Polyskin(®), and Biobrane(®) dressing samples had no negative effect on cell attachment and cell growth when compared to the controls. In a second experiment, the same dressings were exposed to pre-cultured cells in order to exclude the effects of attachment and spreading. The results confirm the above findings. This study could be of interest for establishing skin cell grafting therapies in burn medicine and also for wound care in general.

Early lower extremity fracture fixation and the risk of early pulmonary embolus: filter before fixation?

BACKGROUND Venous thromboembolism is a major cause of morbidity and mortality after injury. Prophylactic anticoagulation is often delayed as a result of injuries or required procedures. Those patients at highest risk in this early vulnerable window postinjury are not well characterized. We sought to determine those patients at highest risk for an early pulmonary embolism (PE) after injury. METHODS A retrospective analysis using data derived from a large state wide trauma registry (1997-2007) was performed. Patients with a documented PE and time of occurrence were selected (n = 712). Patients with fat emboli and lower extremity vascular injuries were excluded. Patients with a PE within the first 72 hours of admission (EARLY, n = 122) were compared with those with DELAYED presentation. Kaplan-Meier survival analysis was used to characterize the timing of death between the two groups. Backward stepwise logistic regression was used to determine independent risk factors for EARLY PE relative to those with DELAYED PE. RESULTS EARLY and DELAYED groups were similar in age, gender, Glasgow Coma Scale, emergency department systolic blood pressure, and injury mechanism. The EARLY PE group had a lower Injury Severity Score but injuries more commonly included femur fracture. Kaplan-Meier analysis revealed that EARLY PE patients have a significantly higher risk of early mortality relative to DELAYED PE patients (p = 0.012). Regression analysis revealed that the only independent risk factor for EARLY PE was lower extremity/pelvic orthopedic fixation (<48 hours from injury). The risk of EARLY PE was more than threefold higher (odds ratios, 3.85; 95% CI, 1.9-7.6; p < 0.001) for those who underwent early lower extremity orthopedic fixation versus those who did not. CONCLUSION Early lower extremity/pelvis orthopedic fixation is the single independent predictor of EARLY PE in this patient cohort. Venous thromboembolism/PE prevention strategies should be made a priority in this group of patients, including early preoperative institution of anticoagulation prophylaxis. These results suggest that those with contraindications to early anticoagulation may benefit from insertion of retrievable inferior vena cava filters preoperatively.