Browsing School, Graduate by Subject "Wounds and Injuries"
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Cellular Changes in Response to Embedded Fragments: An Animal Surveillance ModelBackground: Explosive munitions have wounded approximately 50,000 service members in the Global War on Terrorism. Medical surveillance programs use traditional x-ray as a method of monitoring embedded metal fragments in the body. X-ray replicates a two-dimensional image of bone and air filled structures, it does not display the soft tissue. Tomographic imaging allows specific measured slices of the subject to be obtained in a quantitative manner to display anatomic structures like tumors. Purpose: The purpose of this pilot study was to determine the sensitivity and specificity of small animal Positron Emission Tomography - Computed Tomography (PET-CT) in identifying metabolic changes in muscle tissue surrounding a heavy metal tungsten alloy and compare this imaging to traditional x-ray images. Methods: In the first experiment Fischer 344 male rats were randomly assigned to three groups (implanted with heavy metal tungsten alloy (HMTA) pellets, tantalum (Ta) pellets as the control metal or Sham control without pellet implantation). One rat was in each category for the first experiment. Animals received a series of x-rays and 18F-fluoro-2-deoxy-D-glucose (FDG) and18F-3'-fluoro-3'-deoxy-L-thymidine (FLT) PET-CT scans over 16 weeks. The second experiment used a larger sample of (2 Sham, 15 Ta, 15 HMTA) animals and FDG PET-CT scans. Tracer uptake was quantified using the standard unit value (SUV). Imaging data were compared between groups and over time. Sensitivity and specificity were determined. Receiver Operating Characteristic (ROC) curve and the area under the curve (AUC) were calculated. Histopathology was assessed by a pathologist, blinded to treatment group. Results: Increased FDG uptake was associated with an aggressive malignancy in the HMTA implanted rats. A significant difference in FDG uptake between the Ta and HMTA animals and a significant change in tracer uptake over the sixteen weeks for the HMTA animals was found. PET-CT imaging had a sensitivity of 86% and specificity of 100% and the area under the curve (AUC) .938. Conclusion: PET-CT imaging provided information on metabolic changes occurring at the site of the implanted metals not available from x-rays. PET-CT imaging and can be a useful tool in the surveillance of toxic embedded fragments.
Efficacy of Acute Pain Management on Chronic Pain Following Lower Extremity TraumaBackground: Many patients with traumatic injuries report chronic pain, with injuries to the lower extremity resulting in higher rates than other sites. High pain intensity at the time of injury is a risk factor for chronic pain, but it is not clear what specific acute pain patterns following injury influence the development of chronic pain. In addition, it is not known whether chronic pain in this patient population includes symptoms of heightened sensitivity to innocuous and noxious stimuli, which have been reported in other chronic pain conditions. Purpose: To examine the relationship between post-trauma acute pain status and the incidence of chronic pain, and to test for hypo- or hypersensitivity to innocuous and noxious thermal and mechanical stimuli in patients with lower extremity traumatic injuries. Methods: This was a descriptive retrospective cohort study with a cross-sectional component. Patients were contacted by telephone and their pain related to the injury site was assessed. This was followed by a retrospective medical chart review. A sub-sample of patients and healthy controls also underwent sensory testing. Results: In this study 54% of patients experienced no improvement in pain during hospitalization. The mean pain score was higher for patients with chronic pain (78%) compared to patients with no chronic pain (5.1 vs. 4.2), but there were no significant difference between the group based on the pain trajectory. Patients with injuries had higher warmth detection threshold (36.5 vs. 33.2), and current perception threshold (CPT) stimulus-response at 2000 Hz (292 vs. 122) and 250 Hz (76 vs. 35) compared to healthy controls. Conclusion: Consistent with other studies, high pain intensity at the time of injury was associated with chronic pain. The increased warmth perception threshold and increased CPT stimulus-response in cases suggest hypoesthetic nerve function. This is the first study to conduct an in-depth analysis of acute pain intensity patterns and sensory function in patients with traumatic lower extremity injuries and will guide the design of a future longitudinal study.
Hypothermic coagulopathy in trauma: Effect of varying levels of hypothermia on enzyme speed, platelet function and fibrinolytic activityPurpose. The coagulopathy noted in hypothermic trauma patients has been variously theorized to be caused by either enzyme inhibition, platelet alteration, or fibrinolytic processes, but no study has examined the possibility that all three processes may work in conjunction. The purpose of this study was to determine the interrelationship of these three mechanisms as the causes of coagulopathy in adult trauma patients at varying levels of clinically common hypothermia (33.0 degrees C-36.9 degrees C). Methods. Of 232 consecutive adult trauma patients presenting to a Level I Trauma Center, n = 112 met the inclusion criteria of an Injury Severity Score of 9 or greater and time since injury of less than 2 hours. Patients with frank DIC at presentation were excluded. Of the included patients, 40 were normothermic and 72 were hypothermic (>=37 degrees C, n = 40, 36 superscript 9-36 degrees C, n = 29; 35 superscript 9-35 degrees C, n = 20; 34 superscript 9-34 degrees C, n = 16; 33 superscript 9-33 degrees C, n = 7). Included patients were prospectively studied with thrombelastography adjusted to core body temperature. Thrombelastography measures the shear elasticity of blood and is sensitive to interacting cellular and plasmatic components. Six parameters of blood clotting were analyzed (two each for enzyme speed, platelet activity, and fibrinolysis), and an overall index of coagulation was calculated. Additionally, PT, aPTT, platelets, CO2, hemoglobin, hematocrit, and ISS were measured. Results. Analysis by MANOVA of the relationship between coagulation and temperature demonstrated that in hypothermic trauma patients, 34 degrees C was the critical point where enzyme activity slowed significantly (p<.0001), and significant alteration in platelet activity was seen (p<.001). Fibrinolysis was not signifcantly different at an of the measured temperatures (p>.25). The coagulation index was also significantly lower for the patients with temperatures below 34 degrees C (p<.001). Conclusions. Enzyme activity slowing and decreased platelet function individually contribute to hypothermic coagulopathy in trauma patients, particularly below 34.0 degrees C. All three coagulation measure affected are part of the polymerization process of platelets and fibrin, and this may be the mechanism by which the alteration in coagulation occurs.