BACKGROUND The optimal method of vascular control and resuscitation in patients with life-threatening, extrathoracic torso hemorrhage remains debated. Guidelines recommend emergency department thoracotomy (EDT) with aortic clamping, although transabdominal aortic clamping followed by vascular control and direct vascular control (DVC) without aortic clamping are alternatives. The objective of this study is to compare the effectiveness of three approaches to extrathoracic torso hemorrhage in a large animal model. METHODS Adolescent swine (Sus Scrofa)(mean weight = 80.9 kg) were randomized into three groups all of which had class IV shock established by hemorrhage from an iliac artery injury. Group 1: EDT with thoracic aortic clamping (N = 6); group 2: transabdominal supraceliac aortic clamping (SCC; N = 6); and group 3: DVC of bleeding site without aortic clamping (N = 6). After hemorrhage, EDT or SCC was performed in groups 1 and 2, respectively, with subsequent exploration of the bleeding site and placement of a temporary vascular shunt (TVS). Group 3 (DVC) underwent direct exploration of the injury and placement of a TVS. All groups were resuscitated to predefined physiologic endpoints over 6 hours with repeated measures of central and cerebral perfusion and end-organ function at standardized time points. Postmortem tissue analysis was performed to quantify injury to critical tissue beds. RESULTS There was no difference in mortality among the groups and no TVS failures. Central aortic pressure, carotid flow, and partial pressure brain tissue oximetry, all demonstrated increases in EDT and SCC after application of the aortic clamp relative to DVC (p < 0.05). During resuscitation, serum lactate levels were higher in EDT compared with SCC and DVC (6.85 vs. 3.08 and 2.15, respectively; p < 0.05) and serum pH in EDT reflected greater acidosis than SCC and DVC (7.24 vs. 7.36 and 7.39, respectively; p < 0.05). EDT and SCC required more intravenous fluid than DVC (2,166 mL and 2,166 mL vs. 667 mL, respectively; p < 0.05) and more vasopressors were used in EDT and SCC compared with DVC (52.1 μg and 43.5 μg vs. 12.4 μg, respectively; p < 0.05). Brain and myocardial tissue stains demonstrated the same degree of acute ischemic changes in all groups. CONCLUSION Although aortic clamping increases central and cerebral perfusion, DVC results in less physiologic derangement. The optimal method of aortic control would incorporate the benefits of maintained central pressure with less associated morbidity. Clinical studies evaluating DVC are warranted.

BACKGROUND Noncompressible torso hemorrhage is the leading cause of potentially preventable death on the modern battlefield. The objective of this study is to characterize resuscitative aortic balloon occlusion (BO) compared to thoracotomy with aortic clamping in a model of hemorrhagic shock. METHODS A total of 18 swine (3 groups; 6 animals/group) were used in this study. Swine in class IV shock underwent no aortic occlusion (NO), thoracotomy and clamp occlusion (CO), or endovascular BO. Animals in the NO group underwent direct placement of a temporary vascular shunt (TVS) at the injury site, whereas animals in the CO and BO groups underwent aortic occlusion before TVS placement. Hemodynamic and physiologic measures were collected. RESULTS The central aortic pressure, carotid blood flow and brain oxygenation as measured by oximetry increased in the CO and BO groups compared to the NO group (P <.05). During resuscitation, the BO group was less acidotic than the CO group (pH,7.35 vs 7.24; P <.05) with a lower serum lactate level (4.27 vs 6.55; P <.05) and pCO2 level (43.5 vs 49.9; P <.05). During resuscitation, the BO group required less fluid (667 mL vs 2,166 mL; P <.05) and norepinephrine (0 mcg vs 52.1 mcg; P <.05) than the CO group. CONCLUSION Resuscitative aortic BO increases central perfusion pressures with less physiologic disturbance than thoracotomy with aortic clamping in a model of hemorrhagic shock. Endovascular BO of the aorta should be explored further as an option in the management of noncompressible torso hemorrhage.

BACKGROUND Noncompressible hemorrhage from central vascular injuries remains the leading cause of preventable death in modern combat. This report introduces a large animal model of noncompressible torso hemorrhage, which permits assessment of the various approaches to this problem. METHODS Yorkshire swine were anesthetized and monitoring devices for central aortic pressure, carotid flow, and intracerebral and transcutaneous brain oximetry were applied. Class IV hemorrhagic shock was induced through an iliac arterial injury and animals were subjected to different vascular control methods including thoracic aortic clamping, supraceliac aortic clamping, direct vascular control, and proximal endovascular balloon occlusion. After vascular control, the injury was shunted, and damage control resuscitation was continued. Serum markers, intravenous fluid volumes, and vasopressor requirements were tracked over a subsequent resuscitation period. Postmortem tissue analysis was performed to compare levels of acute ischemic injury between groups. RESULTS The protocol for animal preparation, hemorrhage volume, open surgical technique, and posthemorrhage resuscitation was developed using four animals. The endovascular approach was developed using two additional animals. After model development, treatment animals subsequently underwent noncompressible hemorrhage with thoracic aortic clamping, supraceliac aortic clamping, direct vascular control, and endovascular aortic occlusion. Premature death occurred in one animal in the direct vascular control group. CONCLUSION This study presents a large animal model of class IV hemorrhagic shock from noncompressible hemorrhage, which permits comparison of various vascular control methods to address this challenging problem. Future studies using this model as the standard will allow further development of strategies for the management of noncompressible hemorrhage.

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The extreme albedo asymmetry of Saturn's moon Iapetus, which is about 10 times brighter on its trailing hemisphere than on its leading hemisphere, has been an enigma for three centuries. Deposition of exogenic dark material on the leading side has been proposed as a cause, but cannot alone explain the global shape, sharpness and complexity of the transition between Iapetus' bright and dark terrain. We demonstrate that all these characteristics, and the asymmetry's large amplitude, can be plausibly explained by runaway global thermal migration of water ice, triggered by the deposition of dark material on the leading hemisphere. This mechanism is unique to Iapetus among the Saturnian satellites because its slow rotation produces unusually high daytime temperatures and H(2)O sublimation rates for a given albedo.

BACKGROUND: Temporary vascular shunting to restore flow after vascular injury has been advocated. The effectiveness of this adjunct in protecting against ischemic injury has not been established. This study will assess the temporal impact of shunts on ischemic injury and arterial flow. METHODS: A porcine model of hind-limb ischemia via iliac artery occlusion was used (N = 36; weight [kg]+/- SD: 89 +/- 4.4). Animals were randomized into one control (Iscctrl) and four study groups (Isc0, Isc1, Isc3, and Isc6) according to ischemic time. Shunt placement followed ischemia, and flow and circulating injury markers were collected incrementally during 18 hours of reperfusion. Flow proportions and a calculated Ischemia Injury Index were used to characterize group differences. RESULTS: There were no intergroup differences concerning initial weight, hemodynamic, or laboratory values. Shunt patency was 92% in the absence of anticoagulation. The proportion of common femoral arterial flow to baseline flow in the Isc6 group was lower than the Iscctrl group (p = 0.02). There was a similar trend with the Isc1 and Isc3 groups. The Ischemia Injury Index demonstrated that there was a difference in the Isc3 and Isc6 groups (late shunt placement) compared with the Iscctrl, Isc0, and Isc1 groups (early shunt placement)(p < 0.001). CONCLUSION: This study provides physiologic insight into the benefit of shunts in a model of extremity ischemia. Early shunting protects the extremity from further ischemic insult and reduces circulating markers of tissue injury. Additionally, the presence of a shunt does not increase the Ischemic Injury Index and patency is maintained in the absence of heparinization.

Part 1 concentrated on implications of dental trauma especially prior to and during orthodontic treatment. This paper examines the literature supporting various treatment options for poor prognosis anterior teeth and subsequent space generated when these teeth are lost. The role of an interdisciplinary team in managing this clinical situation is essential to obtain optimal results and an orthodontist is an essential member. Although some treatment options are not provided by orthodontists it is important that they have some knowledge of these and the latest research that support their use. Other techniques lie very much within the orthodontic remit. Treatment options can be split into maintaining the failing tooth or extraction and restoration of the edentulous gap. This paper reviews various treatment options including periodontal regeneration, surgical repositioning and distraction osteogenesis, composite build up to incisal levels and decoronation when maintaining a failing tooth. When extraction and restoration of edentulous gap is required the following treatment modalities are discussed: extraction technique to retain bone quantity, orthodontic space closure and opening (site development), autotransplantation, partial denture, resin bonded bridge and implants. All these options should be considered and available to an interdisciplinary team to ensure optimal care of children with anterior teeth of poor prognosis.

This is the first of two papers discussing the implications of dental trauma for patients requiring orthodontic treatment. This paper will focus on the factors the orthodontic specialist should consider when contemplating movement of traumatized teeth. The prevalence of dental trauma and the recognition and prevention of traumatic injuries are discussed. The evidence available in the literature relating to orthodontic tooth movement in vital and endodontically treated traumatized teeth is explored. The interdisciplinary management of root fractured and intruded teeth receive special attention. The second paper will look at the role of the specialist team in the management of failing anterior teeth and will outline possible treatment options for children and adolescents encountering such situations. Avulsion injuries and tooth transplantation are considered in particular detail.