A simplified mathematical model for thrombin generation.

A new phenomenological mathematical model based directly on laboratory data for thrombin generation and having a patient-specific character is described. A set of the solved equations for cell-based models of blood coagulation that can reproduce the temporal evolution of thrombin generation is proposed; such equations are appropriate for use in computational fluid dynamic (CFD) simulations. The initial values for the reaction rates are either taken from already existing model or experimental data, or they can obtained from simple reasoning under certain assumptions; it is shown that coefficients can be adjusted in order to fit a range of different thrombin generation curves as derived from thrombin generation assays. The behaviour of the model for different platelet concentration seems to be in good agreement with reported experimental data. It is shown that the reduced set of equations used represents to a good approximation a low-order model of the detailed mechanism and thus it can represent a cost-effective and-case specific mathematical model of coagulation reactions up to thrombin generation.

Management of blunt bowel and mesenteric injuries: Experience at the Alfred hospital.

BACKGROUND: The incidence of blunt bowel and mesenteric injury (BBMI) has increased recently in blunt abdominal trauma, possibly due to an increasing number of high-speed motor accidents and the use of seat belts. OBJECTIVE: Our aim was to identify the factors determining the time of surgical intervention and how they affect the outcome of the patient with BBMI. This was achieved by reviewing our experience as a major Victorian trauma service in the management of bowel and mesenteric injuries and comparing this to the experiences reported in the literature. METHODS: A retrospective study reviewing 278 consecutive patients who presented to the Alfred trauma center with blunt bowel and mesenteric injuries over a 6-year period. RESULTS: The patient cohort comprised 278 patients with BBMI (66% were male, 34% were female), of whom 80% underwent a laparotomy, 17% were treated conservatively and 3% were diagnosed post-mortem. In terms of time from admission to laparotomy, 67% were treated within 0-4 h, 9% within 4-8 h, 3% within 8-12 h, 10% within 12-24 h, 4% within 24-48 h and 7% at >48 h. A focused abdominal sonography for trauma (FAST) was performed in 86 patients, of whom 51% had a positive FAST, 44% had a negative FAST and 4% had an equivocal FAST. Overall, 13% of the patient cohort did not have a FAST. Computerized tomography (CT) scans were undertaken preoperatively in 68% of the patients, revealing free gas (22% of patients), bowel-wall thickening (31%), fat and mesenteric stranding or hematoma (38%) and free fluid with no solid organ injury (43%). CONCLUSION: The timing of surgical intervention in cases of BBMI is mostly determined by the clinical examination and the results of the helical CT scan findings. The FAST lacks sensitivity and specificity for identifying bowel and mesenteric trauma. A delayed diagnosis of > 48 h has a significantly higher bowelrelated morbidity but not mortality.

Definitive management of acute cardiac tamponade secondary to blunt trauma.

Blunt cardiac injuries are a leading cause of fatalities following motor-vehicle accidents. Injury to the heart is involved in 20% of road traffic deaths. Structural cardiac injuries (i.e. chamber rupture or perforation) carry a high mortality rate and patients rarely survive long enough to reach hospital. Chamber rupture is present at autopsy in 36-65% of death from blunt cardiac trauma, whereas in clinical series it is present in 0.3-0.9% of cases and is an uncommon clinical finding. Patients with large ruptures or perforations usually die at the scene or in transit--the rupture of a cardiac cavity, coronary artery or intrapericardial portion of a major vein or artery is usually instantly fatal because of acute tamponade. The small, rare, remaining group of patients who survive to hospital presentation usually have tears in a cavity under low pressure and prompt diagnosis and surgery can now lead to a survival rate of 70-80% in experienced trauma centres. As regional trauma systems evolve, patients with severe, but potentially survivable cardiac injury are surviving to ED. Two distinct syndromes are apparent--haemorrhagic shock and cardiac tamponade. Any patient with severe chest trauma, hypotension disproportionate to estimated loss of blood or with an inadequate response to fluid administration should be suspected of having a cardiac cause of shock. For patients with severe hypotension or in extremis, the treatment of choice is resuscitative thoracotomy with pericardotomy. Closed chest cardiopulmonary resuscitation is ineffective in these circumstances. Blunt traumatic cardiac injury presenting with shock is associated with a poor prognosis. The majority of survivors of blunt or penetrating cardiac injury present to the ED/trauma centre with vital signs. The main pathophysiologic determinant for most survivors is acute pericardial tamponade. The presence of normal clinical signs or normal ECG studies does not exclude tamponade. In recent years the widespread availability and use of ultrasound for the initial assessment of severely injured patients has facilitated the early diagnosis of cardiac tamponade and associated cardiac injuries. Two cases of survival from blunt traumatic cardiac trauma are described in the present paper to demonstrate survivability in the context of rapid assessment and intervention.

The evolution of an integrated State Trauma System in Victoria, Australia.

The incidence of major trauma and associated fatalities in the State of Victoria, Australia, have declined over 20 years following the successful implementation of strategies to modify environmental and behavioural factors that contribute to motor vehicle injuries. However, several system deficiencies in the management of major trauma patients had remained unresolved. To investigate these shortfalls the State Government of Victoria established a task force in 1997 to review trauma and emergency services. The task force adopted the principle of "the right patient to the right hospital in the shortest time" and in 2000 began to deploy an integrated State Trauma System. Implementation of such a system required the designation of specific hospitals of various levels to care for trauma patients; the concentration of trauma expertise at these centres; integration and coordination between the service providers; development of agreed triage and transfer protocols and improved education, training and research programs. A statewide major trauma database was established to enable system monitoring and facilitate further enhancements. The Victorian experience with the development of an integrated trauma system should aid in the development of similar systems nationally and internationally and is described in this paper.