Infant movement classification through pressure distribution analysis.

BACKGROUND: Aiming at objective early detection of neuromotor disorders such as cerebral palsy, we propose an innovative non-intrusive approach using a pressure sensing device to classify infant general movements. Here we differentiate typical general movement patterns of the "fidgety period" (fidgety movements) vs. the "pre-fidgety period" (writhing movements). METHODS: Participants (N = 45) were sampled from a typically-developing infant cohort. Multi-modal sensor data, including pressure data from a pressure sensing mat with 1024 sensors, were prospectively recorded for each infant in seven succeeding laboratory sessions in biweekly intervals from 4 to 16 weeks of post-term age. 1776 pressure data snippets, each 5 s long, from the two targeted age periods were taken for movement classification. Each snippet was pre-annotated based on corresponding synchronised video data by human assessors as either fidgety present or absent. Multiple neural network architectures were tested to distinguish the fidgety present vs. fidgety absent classes, including support vector machines, feed-forward networks, convolutional neural networks, and long short-term memory networks. RESULTS: Here we show that the convolution neural network achieved the highest average classification accuracy (81.4%). By comparing the pros and cons of other methods aiming at automated general movement assessment to the pressure sensing approach, we infer that the proposed approach has a high potential for clinical applications. CONCLUSIONS: We conclude that the pressure sensing approach has great potential for efficient large-scale motion data acquisition and sharing. This will in return enable improvement of the approach that may prove scalable for daily clinical application for evaluating infant neuromotor functions.

The movement of a baby is used by health care professionals to determine whether they are developing as expected. The aim of this study was to investigate whether a pad containing sensors that measured pressure occurring as the babies moved could enable identification of different movements of the babies. The results we obtained were similar to those obtained from use of a computer to process videos of the moving babies or other methods using movement sensors. This method could be more readily used to check the movement development of babies than other methods that are currently used.

The future of General Movement Assessment: The role of computer vision and machine learning - A scoping review.

BACKGROUND: The clinical and scientific value of Prechtl general movement assessment (GMA) has been increasingly recognised, which has extended beyond the detection of cerebral palsy throughout the years. With advancing computer science, a surging interest in developing automated GMA emerges. AIMS: In this scoping review, we focused on video-based approaches, since it remains authentic to the non-intrusive principle of the classic GMA. Specifically, we aimed to provide an overview of recent video-based approaches targeting GMs; identify their techniques for movement detection and classification; examine if the technological solutions conform to the fundamental concepts of GMA; and discuss the challenges of developing automated GMA. METHODS AND PROCEDURES: We performed a systematic search for computer vision-based studies on GMs. OUTCOMES AND RESULTS: We identified 40 peer-reviewed articles, most (n = 30) were published between 2017 and 2020. A wide variety of sensing, tracking, detection, and classification tools for computer vision-based GMA were found. Only a small portion of these studies applied deep learning approaches. A comprehensive comparison between data acquisition and sensing setups across the reviewed studies, highlighting limitations and advantages of each modality in performing automated GMA is provided. CONCLUSIONS AND IMPLICATIONS: A "method-of-choice" for automated GMA does not exist. Besides creating large datasets, understanding the fundamental concepts and prerequisites of GMA is necessary for developing automated solutions. Future research shall look beyond the narrow field of detecting cerebral palsy and open up to the full potential of applying GMA to enable an even broader application.

Influence of polyester spacer fabric, cotton, chloroprene rubber, and silicone on microclimatic and morphologic physiologic skin parameters in vivo.

BACKGROUND: Skin diseases can develop upon disadvantageous microclimate in relation to skin contact with textiles of supporting devices. Increased temperature, moisture, mechanical fracture, pressure, and inflammatory processes often occur mutually and enhance each other in their adverse effects. Therefore, the early prevention of skin irritations by improvement of microclimatic properties of skin in contact with supporting devices is important. MATERIALS AND METHODS: In this study, the microclimate under occlusion with polyester, cotton, chloroprene rubber, and silicone textiles, used for supporting devices, was analyzed by determining several characteristic physiologic skin parameters in vivo, including temperature, moisture, and transepidermal water loss (TEWL). This is achieved by comparing a miniaturized in vivo detection device with several established optical and sensory methods in vivo. RESULTS: A highly significant TEWL decrease was found after polyester, chloroprene rubber, and silicone application. The application of all materials showed highly significant decrease in skin surface temperature, with chloroprene rubber showing the lowest. Similarly, all materials showed highly significant increase in relative moisture, where the highest increase was found for chloroprene rubber and silicone and the lowest increase for cotton. The cutaneous carotenoid concentration of chloroprene rubber, silicone, and polyester decreased. A manipulation of the surface structure of the stratum corneum was recognized for all materials except for cotton by laser scanning microscopy. CONCLUSION: The skin parameters temperature, relative moisture, antioxidant status, and TEWL can effectively characterize the microclimatic environment during occlusion with medical supporting materials. These parameters could potentially be used to develop standardized testing procedures for material evaluation.

Designs and performance of three new microprocessor-controlled knee joints.

A crossover design study with a small group of subjects was used to evaluate the performance of three microprocessor-controlled exoprosthetic knee joints (MPKs): C-Leg 4, Plié 3 and Rheo Knee 3. Given that the mechanical designs and control algorithms of the joints determine the user outcome, the influence of these inherent differences on the functional characteristics was investigated in this study. The knee joints were evaluated during level-ground walking at different velocities in a motion analysis laboratory. Additionally, technical analyses using patents, technical documentations and X-ray computed tomography (CT) for each knee joint were performed. The technical analyses showed that only C-Leg 4 and Rheo Knee 3 allow microprocessor-controlled adaptation of the joint resistances for different gait velocities. Furthermore, Plié 3 is not able to provide stance extension damping. The biomechanical results showed that only if a knee joint adapts flexion and extension resistances by the microprocessor all known advantages of MPKs can become apparent. But not all users may benefit from the examined functions: e.g. a good accommodation to fast walking speeds or comfortable stance phase flexion. Hence, a detailed comparison of user demands and performance of the designated knee joint is mandatory to ensure a maximum in user outcome.

Bipolar radio-frequency-induced thermofusion of intestinal tissue - In vivo evaluation of a new fusion technique in an experimental study.

PURPOSE: Bipolar radio-frequency-induced thermofusion (BiRTh) of intestinal tissue might replace conventional stapling devices which are associated with technical and functional complications. Previous results of our study group confirmed the feasibility to fuse intestinal tissue using BiRTh-induced thermofusion ex vivo. The aim of this study was now to evaluate the efficacy of fusing intestinal tissue in vivo by BiRTh-induced thermofusion. MATERIALS AND METHODS: In male Wistar rats a blind bowel originating from the caecum was closed either by BiRTh (n = 24) or conventional suture (n = 16). At 6 h, 48 h, 4 days, and 2 weeks after the procedure caecum bursting pressure was measured to compare both groups. RESULTS: In total 18 of 21 (85.7%) thermofused and 15 of 16 (93.7%) sutured cecal stumps were primarily tight and leakage-proof (p > 0.05). The operative time was comparable in both groups without significant differences. Both groups showed increases in bursting pressure over the post-operative period. The mean bursting pressure for thermofusion was 47.8, 48.3, 55.2, and 68.0 mmHg, compared to 69.8, 51.5, 70.0 and 71.0 mmHg in the hand-sutured group (p > 0.05) after 6 h, 48 h, 4 days, and 2 weeks, respectively. CONCLUSION: These results suggest that BiRTh-induced thermofusion is a safe and feasible method for fusing intestinal tissue in this experimental in vivo model and could be an innovative approach for achieving gastrointestinal anastomoses.

Human Achilles tendon plasticity in response to cyclic strain: effect of rate and duration.

High strain magnitude and low strain frequency are important stimuli for tendon adaptation. Increasing the rate and duration of the applied strain may enhance the adaptive responses. Therefore, our purpose was to investigate the effect of strain rate and duration on Achilles tendon adaptation. The study included two experimental groups (N=14 and N=12) and a control group (N=13). The participants of the experimental groups exercised according to a reference protocol (14 weeks, four times a week), featuring a high strain magnitude (~6.5%) and a low strain frequency (0.17 Hz, 3 s loading/3 s relaxation) on one leg and with either a higher strain rate (one-legged jumps) or a longer strain duration (12 s loading) on the other leg. The strain magnitude and loading volume were similar in all protocols. Before and after the interventions, the tendon stiffness, Young's modulus and cross-sectional area were examined using magnetic resonance imaging, ultrasound and dynamometry. The reference and long strain duration protocols induced significantly increased (P<0.05) tendon stiffness (57% and 25%), cross-sectional area (4.2% and 5.3%) and Young's modulus (51% and 17%). The increases in tendon stiffness and Young's modulus were higher in the reference protocol. Although region-specific tendon hypertrophy was also detected after the high strain rate training, there was only a tendency of increased stiffness (P=0.08) and cross-sectional area (P=0.09). The control group did not show any changes (P=0.86). The results provide evidence that a high strain magnitude, an appropriate strain duration and repetitive loading are essential components for an efficient adaptive stimulus for tendons.

Designs and performance of microprocessor-controlled knee joints.

In this comparative study, three transfemoral amputee subjects were fitted with four different microprocessor-controlled exoprosthetic knee joints (MPK): C-Leg, Orion, Plié2.0, and Rel-K. In a motion analysis laboratory, objective gait measures were acquired during level walking at different velocities. Subsequent technical analyses, which involved X-ray computed tomography, identified the functional mechanisms of each device and enabled corroboration of the performance in the gait laboratory by the engineering design of the MPK. Gait measures showed that the mean increase of the maximum knee flexion angle at different walking velocities was closest in value to the unaffected contralateral knee (6.2°/m/s) with C-Leg (3.5°/m/s; Rel-K 17.0°/m/s, Orion 18.3°/m/s, and Plié2.0 28.1°/m/s). Technical analyses corroborated that only with Plié2.0 the flexion resistances were not regulated by microprocessor control at different walking velocities. The muscular effort for the initiation of the swing phase, measured by the minimum hip moment, was found to be lowest with C-Leg (-82.1±14.1 Nm; Rel-K -83.59±17.8 Nm, Orion -88.0±16.3 Nm, and Plié2.0 -91.6±16.5 Nm). Reaching the extension stop at the end of swing phase was reliably executed with both Plié2.0 and C-Leg. Abrupt terminal stance phase extension observed with Plié2.0 and Rel-K could be attributed to the absence of microprocessor control of extension resistance.

Bipolar radiofrequency-induced thermofusion of intestinal anastomoses--feasibility of a new anastomosis technique in porcine and rat colon.

PURPOSE: In recent years, vessel sealing has become a well-established method in surgical practice for sealing and transecting vessels. Since this technology depends on the fusion of collagen fibers abundantly present in the intestinal wall, it should also be possible to create intestinal anastomoses by thermofusion. Bipolar radiofrequency-induced thermofusion of intestinal tissue may replace traditionally used staples or sutures in the future. The aim of this study was to evaluate the feasibility of fusing intestinal tissue ex vivo by bipolar radiofrequency-induced thermofusion. MATERIALS AND METHODS: An experimental setup for temperature-controlled bipolar radiofrequency-induced thermofusion of porcine (n = 30) and rat (n = 18) intestinal tissue was developed. Colon samples were harvested and then anastomosed, altering compressive pressure to examine its influence on anastomotic bursting pressure during radiofrequency-induced anastomotic fusion. For comparison, mechanical stapler anastomoses of porcine colonic samples and conventional suturing of rat colonic samples identical to those used for fusion experiments were prepared, and burst pressure was measured. RESULTS: All thermofused colonic anastomoses were primarily tight and leakage proof. For porcine colonic samples, an optimal interval of compressive pressure (1,125 mN/mm(2)) with respect to a high amount of burst pressure (41 mmHg) was detected. The mean bursting pressure for mechanical stapler anastomosis was 60.7 mmHg and did not differ from the thermofusion (p = 0.15). Furthermore, the mean bursting pressure for thermofusion of rat colonic samples was up to 69.5 mmHg for a compressive pressure of 140 mN/mm(2). CONCLUSION: These results confirm the feasibility to create experimental intestinal anastomoses using bipolar radiofrequency-induced thermofusion. The stability of the induced thermofusion showed no differences when compared to that of conventional anastomoses. Bipolar radiofrequency-induced thermofusion of intestinal tissue represents an innovative approach for achieving gastrointestinal anastomoses.

Pilot study of bipolar radiofrequency-induced anastomotic thermofusion-exploration of therapy parameters ex vivo.

PURPOSE: Vessel sealing has been well-established in surgical practice in recent years. Bipolar radiofrequency-induced thermofusion (BIRTH) of intestinal tissue might replace traditionally used staples or sutures in the near future. In this experimental study, the influence of compressive pressure, fusion temperature, and duration of heating on the quality of intestinal anastomosis was investigated to obtain the relevant major parameters for the in vivo use of this system. METHODS: An experimental setup for a closed-loop temperature-controlled bipolar radiofrequency-induced thermofusion of porcine intestinal tissue was developed. Twenty-four colon samples were harvested from nine different Saalower-Kräuter pigs and then anastomosed altering compressive pressure on five different levels to explore its influence on anastomotic bursting pressure. RESULTS: The anastomotic bursting strength depends on the compressive pressure applied to the colonic fusion site. An optimal interval of compressive pressure (CP = 1.125 N/mm(2)) in respect of a high amount of burst pressure was detected. A correlation (r = 0.54, p = 0.015) of burst pressure to delta compression indicated that increasing colonic wall thickness probably strengthens the anastomotic fusion. CONCLUSION: This study is a first step to enlighten the major parameters of tissue fusion, though effects and interactions of various main parameters of bipolar radiofrequency-induced thermofusion of colonic tissue remain unclear. Further studies exploring the main effects and interactions of tissue and process parameters to the quality of the fusion site have to follow.

Framework conditions and requirements to ensure the technical functional safety of reprocessed medical devices.

Testing and restoring technical-functional safety is an essential part of medical device reprocessing. Technical functional tests have to be carried out on the medical device in the course of the validation of reprocessing procedures. These ensure (in addition to the hygiene tests) that the reprocessing procedure is suitable for the medical device. Functional tests are, however, also a part of reprocessing procedures. As a stage in the reprocessing, they ensure for the individual medical device that no damage or other changes limit the performance. When determining which technical-functional tests are to be carried out, the current technological standard has to be taken into account in the form of product-specific and process-oriented norms. Product-specific norms primarily define safety-relevant requirements. The risk management method described in DIN EN ISO 14971 is the basis for recognising hazards; the likelihood of such hazards arising can be minimised through additional technical-functional tests, which may not yet have been standardised. Risk management is part of a quality management system, which must be bindingly certified for manufacturers and processors of critical medical devices with particularly high processing demands by a body accredited by the competent authority.