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The level of digitalization and automation, including robotic systems, is increasing in modern operating theaters. However, the integration of such systems within an already complex and limited environment creates challenges, such as collaboration with dynamic robots and thus potential collisions. Yet, the placements of robotic systems largely rely on empirical guidelines provided by manufacturers, which do not account for the specific requirements of operating theater layouts or individual surgical procedures. In this work, we propose a framework for optimization of robotic set-ups in the operating theater to address these limitations and to enhance the overall workflow efficiency. By utilizing a simulation-based approach, we aim to determine the optimal placement of each surgical equipment within the constrained operating theater environment. In this study, we set the stage for future efforts and demonstrate the effectiveness of our approach by determining the optimal placement of a LBR iiwa 7 R800 as a surgical assistant for an abdominal surgery. Overall this work lays the groundwork for future research that will accommodate more complex scenarios and is a crucial first step towards a holistic workflow optimization in the operating theater.

Cerebral aneurysms are common lesions in the general population and are increasingly treated by endovascular procedures. Training of these methods not only improves the learning period of physicians but also increases patient safety. However, the use of traditional medical training methods such as training in living animal models is decreasing due to high costs and ethical issues, so computer simulations and 3D-printed phantoms are being used instead. A more realistic simulation requires pulsatile blood flow that can be customized and has body temperature. Current simulators that use 3D-printed phantoms are mainly used under X-Ray in an angiography intervention room, therefore a dual-use simulator that is easy to transport and can be used also without X-Ray is desirable. Either it could be used traditionally in an angiography intervention room or externally in any regular room with an image simulation according to rotational angiography. In this work, a prototype for blood flow simulation is presented as a first step towards such simulator and its application is demonstrated through different investigations. The fluid system is capable of simulating a given blood flow profile and the heating system can generate an accurate body temperature. The case can be easily integrated into a modular phantom system and is convenient to transport, although the weight could be further reduced.

Aspiration catheters play an important role in mechanical thrombectomy in interventional neuroradiology as they provide support for stent retrievers or are increasingly used separately for contact aspiration. To evaluate the performance of different aspiration catheters in terms of suction force, most current studies rely on manual measurement methods or the suction force is not measured close to the aspiration catheter tip. Moreover, there is currently no standardized method that records measurements digitally and with high temporal resolution. To overcome these challenges, we propose a new test bench that simulates a dedicated aspiration scenario and takes measurements close to the aspiration catheter tip. To meet the requirements, a simplified vascular phantom, a pressure sensor and a simplified clot model were implemented in the prototype. To demonstrate the applicability of the prototype, two commonly used aspiration catheters were evaluated. The obtained measurements show that it is possible to perform standardized comparisons between aspiration catheters from different manufacturers as well as different aspiration pumps and aspiration tubings and their combinations. The developed prototype overcomes the still widely used manual and semimanual and thus error prone measurement methods for the evaluation of vacuum based thrombectomy systems.

The positive end-expiratory pressure (PEEP) valve is important in the regulation of the pressure at the patient airways in devices for mechanical ventilation. The goal of this work is to derive a model that sufficiently captures the dynamics of the PEEP valve to be used for model-based control design. This paper describes the development of a model for common PEEP valve designs, thus allowing an adoption for different devices. A simplified first principle model with one mechanical degree of freedom is derived, under the assumption that the valve’s membrane behaves similar to a massspring- damper system. Following a grey-box model approach, physical parameters were lumped together and experimentally determined or identified from acquired data. Therefore, a valve test bench was developed to record various series of measurements. It was possible to determine a suitable flow factor which describes the correlation between flow, valve opening and upstream pressure. Additionally, a damping coefficient was estimated, with which the model achieves a good fit to the measured data at low dynamics and flows.

Radial compressors, Blowers, which are often used in modern devices for medical ventilation, are known to have non-linear dynamics regarding the generated pressure. To make them accessible for the large field of linear control theory their model needs to be linearized. This paper uses a gray box model of a blower driven by a brushless direct current (BLDC) motor to design a controller based on feedback linearization. The controller is designed to achieve approximate linear closed loop behavior of the system. The controller is then evaluated concerning reference tracking and disturbance rejection in simulation and on a demonstrator system. The evaluation showed that an approximate linear closed loop behavior was achieved.

For patient safety, it is important that a medical device can safely and reliably perform its intended purpose. The challenge in medical technology is that medical devices are heterogeneous systems and thus no widely applicable standard concepts for functional safety exist in medical technology. This is also reflected in the regulatory landscape, with its rather generally applicable standards. Patient safety is currently achieved by performing continuous risk management with an acceptable level of residual risk. Functional safety and its design concepts, as applied in other industries, have so far found little application in the field of medical technology. In this paper, the automotive safety concept "EGAS" is analyzed with regard to its applicability for medical devices. Based on the investigated example of a medical ventilator, important parallels were found between the automotive and the medical device sector, indicating the possibility of successfully applying the EGAS safety concept to medical devices.

In this study a physiological closed-loop system for arterial CO2 partial pressure control was designed and comprehensively tested using a set of models of the respiratory CO2 gas exchange. The underlying preclinical data were collected from 12 pigs in presence of severe changes in hemodynamic and pulmonary condition. A minimally complex nonlinear state space model of CO2 gas exchange was identified post hoc in different lung conditions. The control variable was measured noninvasively using the endtidal CO2 partial pressure. For the simulation study the output signal of the controller was defined as the alveolar minute volume set value of an underlying adaptive lung protective ventilation mode. A linearisation of the two-compartment CO2 gas exchange model was used for the design of a model predictive controller (MPC). It was augmented by a tube based controller suppressing prediction errors due to model uncertainties. The controller was subject to comparative testing in interaction with each of the CO2 gas exchange models previously identified on the preclinical study data. The performance was evaluated for the system response towards the following five tests in comparison to a PID controller: recruitment maneuver, PEEP titration maneuver, stepwise change in the CO2 production, breath-hold maneuver and a step in the reference signal. A root mean square error of 2.69 mmHg between arterial CO2 partial pressure and the reference signal was achieved throughout the trial. The reference-variable response of the model predictive controller was superior regarding overshoot and settling time.

In order to test medical devices, industry increasingly uses simulators closely reassembling the behaviour of physiological systems. In the context of respiratory therapy, most available simulators are designed based on a ventilated volume. This highly adjustable volume allowing for fast dynamical changes often leads to very costintensive test devices, particularly when incorporating realistic spontaneous breathing. Therefore, in this article we introduce a novel concept for a low-cost lung simulator, capable of mimicking the ventilation behaviour of the human lung at the Y-piece of a mechanical ventilator. The proposed design does not require any enclosed spaces to hold inhaled air nor expensive precise linear actuators adjusting its volume. Instead, the setup is designed based on the design of a mechanical ventilator, connecting the system with one port to the ventilator and then dividing the hose into two independent branches. Each branch has an integrated radial fan and a proportional valve, controlling the inspiratory and expiratory flow, individually. The mass flow and pressure are measured at the systems inlet port, representing the condition at patient airway. In contrast to existing setups, the proposed design is not limited by the physical properties of a volume such as fixed maximum size, allowing the simulation of various types of patients and conditions. Numerical simulations to evaluate this system design showed the ability to generate a realistic spontaneous breathing pattern. With a first experimental setup it was possible to prove the feasibility of this approach, by generating common flow curves during spontaneous breathing. Building on this design, the approach could eventually lead to a more accessible method for testing.

In this study a physiological closed-loop system for arterial CO2 partial pressure control was designed and comprehensively tested using a set of models of the respiratory CO2 gas exchange. The underlying preclinical data were collected from 12 pigs in presence of severe changes in hemodynamic and pulmonary condition. A minimally complex nonlinear state space model of CO2 gas exchange was identified post hoc in different lung conditions. The control variable was measured noninvasively using the endtidal CO2 partial pressure. For the simulation study the output signal of the controller was defined as the alveolar minute volume set value of an underlying adaptive lung protective ventilation mode. A linearisation of the two-compartment CO2 gas exchange model was used for the design of a model predictive controller (MPC). It was augmented by a tube based controller suppressing prediction errors due to model uncertainties. The controller was subject to comparative testing in interaction with each of the CO2 gas exchange models previously identified on the preclinical study data. The performance was evaluated for the system response towards the following five tests in comparison to a PID controller: recruitment maneuver, PEEP titration maneuver, stepwise change in the CO2 production, breath-hold maneuver and a step in the reference signal. A root mean square error of 2.69 mmHg between arterial CO2 partial pressure and the reference signal was achieved throughout the trial. The reference-variable response of the model predictive controller was superior regarding overshoot and settling time. [ABSTRACT FROM AUTHOR]