Biomed Tech 2016; 61 (s90) © by Walter de Gruyter • Berlin • Boston. DOI 10.1515/bmt-2016-5008 S90 ID: J-OP-02 Ventilation with “Expiratory Ventilation Assistance” – In vivo evaluation of a mechanical ventilator prototype Johannes Schmidt, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] Christin Wenzel, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] Marlene Mahn, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] Sashko Spassov, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] Heidi Cristina-Schmitz, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] Silke Borgmann, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] Jörg Haberstroh, Experimental Surgery, Center for Experimental Models and Transgenic Service, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] Stephan Meckel, Department of Neuroradiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] Steffen Wirth, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] Stefan Schumann, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] Emergency access to the airway with small bore catheters is commonly accepted. However, ventilation is limited by insufficient expiratory flow due to the generated high airway resistance. In a controlled in-vivo trial we evaluate a new automatic mechanical ventilator with an “Expiratory Ventilation Assistance” (EVA) via a cuffed endotracheal tube having an inner diameter of 2 mm. This allows a fully controlled ventilation, i.e. flow controlled inspiration and active expiration induced by suctioning. Anesthetised pigs (40-51 kg, 7 per group) were either ventilated with a conventional ventilator (Evita 4, Dräger Medical, Lübeck, Germany; = control group) or the mechanical EVA-ventilator prototype (Ventinova Medical BV, Eindhoven, The Netherlands; = EVA group) for five hours. Respiratory parameters, arterial blood gases (ABG) and hemodynamic markers were recorded hourly. After five hours a computed tomography (CT) of the thorax was performed. For statistical analyses the Welch’s t-test was performed. The EVA-ventilator achieved a minute volume up to 6.2 l/min. Mean airway pressure was significantly higher in the EVA group compared to the control group (12.0 ± 0.6 mbar vs. 8.9 ± 0.2 mbar, p=0.0007). Arterial O2 partial pressure was significantly higher in the EVA-group (142.6 ± 5.6 mmHg vs. 130.7 ± 3.1 mmHg, p=0.006). Despite a significantly lower minute volume in the EVA group (5.5 ± 0.4 l/min vs. 6.7 ± 0.9 l/min, p=0.04), arterial CO2 partial pressure was comparable in both groups (41.3 ± 1.6 mmHg vs. 41.5 ± 1.2 mmHg, p=0.83). Mean arterial pressure was significantly lower in the EVA group (71 ± 9 mmHg vs. 89 ± 9 mmHg, p=0.02). The CT revealed a more constant and steady distribution of ventilation during a breathing cycle in the EVA group. Our results suggest that gas exchange is improved due to increased alveolar ventilation with EVA. Biomed Tech 2016; 61 (s91) © by Walter de Gruyter • Berlin • Boston. DOI 10.1515/bmt-2016-5008 S91 ID: J-OP-03 Pressure-flow characteristics of coaxial tubing systems C. Wenzel, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] S. Schumann, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] J. Spaeth, Department of Anesthesiology and Critical Care, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany, [email protected] During mechanical ventilation, tubing systems represent an essential component of the artificial airways. Conventional, a circular tubing system comprises two separate tubes one for inspiration and one for expiration, a Y-piece and a 90°- connector. Since recently, coaxial tubing systems (coaxTS) are available. These coaxTS include the inspiratory tube within the expiratory tube’s lumen. By design, this facilitates clinical handling. However, the cross section areas of the inspiratory and expiratory tubes are reduced, which may impact resistance to airflow. We hypothesized that coaxTS increase resistance to airflow and related work of breathing (WOB) compared to conventional tubing systems. Therefore, we determined the flow-dependent pressure gradient (∆P) across a conventional reusable tubing system (crTS; composed of two silicone tubes, Y-piece and 90°-connector), a conventional disposable tubing system (cdTS; composed of two plastic tubes, Y-piece and 90°-connector) and coaxTS, the latter two from three different manufacturers. Additionally, ∆P across the isolated 90°-connectors were determined. To test the clinical implications of our findings, the tubing related WOB and perception of discomfort of breathing through the different types of tubing systems were investigated in 14 volunteers. At a representative flow rate of 1.0 L/s coaxTS showed the highest ∆P (5.0±0.1 cmH2O), followed by cdTS (1.4±0.1 cmH2O) and crTS (1.3±0.1 cmH2O; two-way ANOVA, p<0.001). ∆P across coaxTS was significantly higher in expiration compared to inspiration (p<0.001) and varied between manufacturers (p<0.05). At the same flow rate the 90°- connector caused up to 40% from ∆P in cdTS but only 8% in crTS, respectively. Additional WOB was up to fourfold higher in coaxTS compared to crTS (4.0±2.3 vs. 0.95±0.53 J/min; one-way ANOVA, p<0.0001) and discomfort was rated the highest across coaxTS (11 from 14 volunteers). As a result from our study, coaxial tubing systems should be carefully considered in patients with pathologically increased airway resistance. Biomed Tech 2016; 61 (s92) © by Walter de Gruyter • Berlin • Boston. DOI 10.1515/bmt-2016-5008 S92 ID: J-OP-04 Comparative Assessment of Stroke Patients' Upper Limb Tasks to Evaluate a System Based on Inertial Measurement Units and Fuzzy Logic Braulio Roberto Duarte Benitez, Department of Rehabilitation & Prevention Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, Aachen, Germany, [email protected] Catherine Disselhorst-Klug, Department of Rehabilitation & Prevention Engineering, Institute of Applied Medical Engineering, RWTH Aachen University, Aachen, Germany, [email protected] According to the World Health Organization, per year 15 million people suffer a stroke worldwide. Of these, 5 million are permanently disabled. Currently there are several methods to evaluate upper limb movements on stroke patients; they are mostly based on observation by physicians and physiotherapists, whose judgement is influenced by experience and subjective impressions. This study was done on 16 stroke patients, using a system which is based on four Inertial Measurement Units (IMUs) which are composed of accelerometers, gyroscopes, and magnetometers. Each sensor was placed on each segment of the patient´s arm, i.e. scapula, arm, forearm, and hand. Every patient was told to perform simple movements with the arm, such as “move the hand to the mouth” and “hand to the head” starting from a resting position while they were standing, or sitting when requiring a wheelchair. Repeated movements were performed continuously between 15 and 20 times, while the data from the IMUs were recorded. Afterwards, the data were processed to obtain the orientation of every segment of the arm, given as Euler angles in relation to a laboratory coordinate system. The Euler angles were run through a Fuzzy Logic algorithm. The resulting values from a specific repetition were compared with other repetitions of the same exercise, assigning a score to each repetition based on a final scaled value between 0 and 10. Physiotherapists were asked to evaluate the patients´ movements. Comparing their evaluation with the proposed methodology, physiotherapists were able to highlight certain characteristics from the movements on a specific period of the exercise. In contrast with physiotherapists, Fuzzy algorithm considers and processes what the patient performed during the entire exercise. The outcome from the Fuzzy algorithm offered an objective, stable and consistent movement evaluation which was independent of the performed task and the analyzed patient. Biomed Tech 2016; 61 (s93) © by Walter de Gruyter • Berlin • Boston. DOI 10.1515/bmt-2016-5008 S93 ID: J-OP-05