Physiological Signal Monitoring for Identification of Emotional Dysregulation in Children.

Children, particularly those with atypical or delayed development, have a reduced ability to self-regulate their emotions and behaviour. After a number of anxiety or stress provoking events, this reduced regulatory ability can result in a meltdown. Extrinsic signals of an impending meltdown are often recognised and acted on by clinicians or parents. These external indications are also accompanied by internal physiological changes, such as increase in heart rate, skin electrodermal activity, and skin temperature. These physiological signals may be used to predict impending meltdown events and facilitate earlier and effective carer intervention, especially in complex management cases. We present a preliminary study using a wearable sensor system for continuous monitoring of physiological signals to measure and predict emotional changes in school-aged children. Our models are able to correctly classify the behavioural state of a child with 68% mean global model accuracy and up to 85% for person-dependent models. Prediction of emotion and identification of impending meltdowns will potentially assist parents, carers, teachers and clinicians to manage stress and problem behaviours before they escalate, and support self-management strategies throughout the variety of normal daily life.

Residual limb fluid volume change and volume accommodation: Relationships to activity and self-report outcomes in people with trans-tibial amputation.

BACKGROUND: Fluctuations in limb volume degrade prosthesis fit and require users to accommodate changes using management strategies, such as donning and doffing prosthetic socks. OBJECTIVES: To examine how activities and self-report outcomes relate to daily changes in residual limb fluid volume and volume accommodation. STUDY DESIGN: Standardized, two-part laboratory protocol with an interim observational period. METHODS: Participants were classified as "accommodators" or "non-accommodators," based on self-report prosthetic sock use. Participants' residual limb fluid volume change was measured using a custom bioimpedance analyzer and a standardized in-laboratory activity protocol. Self-report health outcomes were assessed with the Socket Comfort Score and Prosthesis Evaluation Questionnaire. Activity was monitored while participants left the laboratory for at least 3 h. They then returned to repeat the bioimpedance test protocol. RESULTS: Twenty-nine people were enrolled. Morning-to-afternoon percent limb fluid volume change per hour was not strongly correlated to percent time weight-bearing or to self-report outcomes. As a group, non-accommodators ( n = 15) spent more time with their prosthesis doffed and reported better outcomes than accommodators. CONCLUSION: Factors other than time weight-bearing may contribute to morning-to-afternoon limb fluid volume changes and reported satisfaction with the prosthesis among trans-tibial prosthesis users. Temporary doffing may be a more effective and satisfying accommodation method than sock addition. Clinical relevance Practitioners should be mindful that daily limb fluid volume change and prosthesis satisfaction are not dictated exclusively by activity. Temporarily doffing the prosthesis may slow daily limb fluid volume loss and should be investigated as an alternative strategy to sock addition.

Effects of socket size on metrics of socket fit in trans-tibial prosthesis users.

The purpose of this research was to conduct a preliminary effort to identify quantitative metrics to distinguish a good socket from an oversized socket in people with trans-tibial amputation. Results could be used to inform clinical practices related to socket replacement. A cross-over study was conducted on community ambulators (K-level 3 or 4) with good residual limb sensation. Participants were each provided with two sockets, a duplicate of their as-prescribed socket and a modified socket that was enlarged or reduced by 1.8mm (∼6% of the socket volume) based on the fit quality of the as-prescribed socket. The two sockets were termed a larger socket and a smaller socket. Activity was monitored while participants wore each socket for 4 weeks. Participants' gait; self-reported satisfaction, quality of fit, and performance; socket comfort; and morning-to-afternoon limb fluid volume changes were assessed. Visual analysis of plots and estimated effect sizes (measured as mean difference divided by standard deviation) showed largest effects for step time asymmetry, step width asymmetry, anterior and anterior-distal morning-to-afternoon fluid volume change, socket comfort score, and self-reported utility. These variables may be viable metrics for early detection of deterioration in socket fit, and should be tested in a larger clinical study.

A Bioimpedance Analysis Platform for Amputee Residual Limb Assessment.

OBJECTIVE: The objective of this research was to develop a bioimpedance platform for monitoring fluid volume in residual limbs of people with trans-tibial limb loss using prostheses. METHODS: A customized multifrequency current stimulus profile was sent to thin flat electrodes positioned on the thigh and distal residual limb. The applied current signal and sensed voltage signals from four pairs of electrodes located on the anterior and posterior surfaces were demodulated into resistive and reactive components. An established electrical model (Cole) and segmental limb geometry model were used to convert results to extracellular and intracellular fluid volumes. Bench tests and testing on amputee participants were conducted to optimize the stimulus profile and electrode design and layout. RESULTS: The proximal current injection electrode needed to be at least 25 cm from the proximal voltage sensing electrode. A thin layer of hydrogel needed to be present during testing to ensure good electrical coupling. Using a burst duration of 2.0 ms, intermission interval of 100 µs, and sampling delay of 10 µs at each of 24 frequencies except 5 kHz, which required a 200-µs sampling delay, the system achieved a sampling rate of 19.7 Hz. CONCLUSION: The designed bioimpedance platform allowed system settings and electrode layouts and positions to be optimized for amputee limb fluid volume measurement. SIGNIFICANCE: The system will be useful toward identifying and ranking prosthetic design features and participant characteristics that impact residual limb fluid volume.