Hardware-in-the-loop simulation of vascular cannula interaction.

Traditionally, the functional development, testing and verification of higher level automation, control and safety functions in extracorporeal circulations systems relies very much on the conduction of animal experiments. This especially applies to functions requiring interaction with the patients physiology. Besides ethical aspects, animal experiments have the disadvantage of higher complexity, limited reproducibility and certain pathological conditions can only be represented with difficulty. An alternative to this can be Hardware-in-the-loop (HIL) simulators.In this paper we present a HIL solution to simulate the hydraulic interaction between the cannula and the connected blood vessel. We derive a hydraulic model for an elastic vessel with particular emphasis on negative transmural pressure. In this case the resistance is mainly determined by collapse phenomena. The next section describes the design of an universal resistance actuator that can simulate vascular resistances in the expected range. Combined in the HIL simulator, the simulation model then generates the setpoint for the actuator while simultaneously receiving the resulting internal states of the hydraulic interface. This creates a truly interactive HIL simulator where the device under test interacts in the same way as with a physiological system.

Local YB-1, Epo, and EpoR concentrations in fractured bones: results from a porcine model of multiple trauma.

Little is known about the impact of multiple trauma (MT)-related systemic hypoxia on osseous protein concentration of the hypoxia transcriptome. To shed light on this issue, we investigated erythropoietin (Epo), erythropoietin receptor (EpoR), and Y-box binding protein 1 (YB-1) concentrations in the fracture zone in a porcine MT + traumatic hemorrhage (TH) model. Sixteen male domestic pigs were randomized into two groups: an MT + TH group and a sham group. A tibia fracture, lung contusion, and TH were induced in the MT + TH group. The total observation period was 72 h. YB-1 concentrations in bone marrow (BM) were significantly lower in the fracture zone of the MT + TH animals than in the sham animals. Significant downregulation of BM-localized EpoR concentration in both unfractured and fractured bones was observed in the MT + TH animals relative to the sham animals. In BM, Epo concentrations were higher in the fracture zone of the MT + TH animals compared with that in the sham animals. Significantly higher Epo concentrations were detected in the BM of fractured bone compared to that in cortical bone. Our results provide the first evidence that MT + TH alters hypoxia-related protein concentrations. The impacts of both the fracture and concomitant injuries on protein concentrations need to be studied in more detail to shed light on the hypoxia transcriptome in fractured and healthy bones after MT + TH.

Impact of anticoagulation and antiplatelet drugs on surgery rates and mortality in trauma patients.

Preinjury anticoagulation therapy (AT) is associated with a higher risk for major bleeding. We aimed to evaluated the influence of preinjury anticoagulant medication on the clinical course after moderate and severe trauma. Patients in the TraumaRegister DGU ≥ 55 years who received AT were matched with patients not receiving AT. Pairs were grouped according to the drug used: Antiplatelet drugs (APD), vitamin K antagonists (VKA) and direct oral anticoagulants (DOAC). The primary end points were early (< 24 h) and total in-hospital mortality. Secondary endpoints included emergency surgical procedure rates and surgery rates. The APD group matched 1759 pairs, the VKA group 677 pairs, and the DOAC group 437 pairs. Surgery rates were statistically significant higher in the AT groups compared to controls (APD group: 51.8% vs. 47.8%, p = 0.015; VKA group: 52.4% vs. 44.8%, p = 0.005; DOAC group: 52.6% vs. 41.0%, p = 0.001). Patients on VKA had higher total in-hospital mortality (23.9% vs. 19.5%, p = 0.026), whereas APD patients showed a significantly higher early mortality compared to controls (5.3% vs. 3.5%, p = 0.011). Standard operating procedures should be developed to avoid lethal under-triage. Further studies should focus on detailed information about complications, secondary surgical procedures and preventable risk factors in relation to mortality.

Hematological and Chemical Profiles in a Porcine Model of Severe Multiple Trauma.

BACKGROUND: Clinical chemistry and hematological tests are widely used to monitor the clinical course of several diseases. However, these parameters are sparse in large-animal models of multiple trauma (MT). Thus, we aimed to provide these missing data to improve future experimental setups in trauma research. METHODS: Male pigs (German Landrace pigs) were randomized into either an MT group (n = 8) including blunt thoracic trauma, tibial fracture, and controlled hemorrhage or a sham group (n = 8) without any trauma. After trauma induction, all animals received intensive care treatment for 72 h under anesthesia, including mechanical ventilation and volume resuscitation. Blood and urine samples were obtained to measure common hematological and chemical parameters before trauma (0 h), after trauma (1.5 h), during resuscitation (2.5 h), after fracture stabilization (3.5 h), and at 12, 24, 48, and 72 h. Statistical analyses were performed using a linear mixed model (group × time) and Welch's ANOVA. RESULTS: MT led to a perceptible immunological reaction. Between groups, significantly different time courses of leukocyte counts (p = 0.034) and lymphocyte proportions (p = 0.001) were observed. Moreover, MT changed the time course of total protein (p = 0.006). Significantly lower concentrations compared to sham were found in MT at each single time point starting at 1.5 h to the end of the observation period (all p < 0.05). CONCLUSIONS: Our results indicate that a traumatic insult leads to significant alterations in the immune system already shortly after trauma. Together with the additional catabolic reactions observed, these alterations might contribute to the occurrence of later complications. The presented data provide valid references for further experimental setups with prolonged observation times, especially in similar porcine models of MT.

Peyton's four-step approach for teaching complex spinal manipulation techniques - a prospective randomized trial.

BACKGROUND: The objectives of this prospective randomized trial were to assess the impact of Peyton's four-step approach on the acquisition of complex psychomotor skills and to examine the influence of gender on learning outcomes. METHODS: We randomly assigned 95 third to fifth year medical students to an intervention group which received instructions according to Peyton (PG) or a control group, which received conventional teaching (CG). Both groups attended four sessions on the principles of manual therapy and specific manipulative and diagnostic techniques for the spine. We assessed differences in theoretical knowledge (multiple choice (MC) exam) and practical skills (Objective Structured Practical Examination (OSPE)) with respect to type of intervention and gender. Participants took a second OSPE 6 months after completion of the course. RESULTS: There were no differences between groups with respect to the MC exam. Students in the PG group scored significantly higher in the OSPE. Gender had no additional impact. Results of the second OSPE showed a significant decline in competency regardless of gender and type of intervention. CONCLUSIONS: Peyton's approach is superior to standard instruction for teaching complex spinal manipulation skills regardless of gender. Skills retention was equally low for both techniques.