Algorithms for Walking Speed Estimation Using a Lower-Back-Worn Inertial Sensor: A Cross-Validation on Speed Ranges.

Walking/gait speed is a key measure for daily mobility characterization. To date, various studies have attempted to design algorithms to estimate walking speed using an inertial sensor worn on the lower back, which is considered as a proper location for activity monitoring in daily life. However, these algorithms were rarely compared and validated on the same datasets, including people with different preferred walking speed. This study implemented several original, improved, and new algorithms for estimating cadence, step length and eventually speed. We designed comprehensive cross-validation to compare the algorithms for walking slow, normal, fast, and using walking aids. We used two datasets, including reference data for algorithm validation from an instrumented mat (40 subjects) and shanks-worn inertial sensors (88 subjects), with normal and impaired walking patterns. The results showed up to 50% performance improvements. Training of algorithms on data from people with different preferred speeds led to better performance. For the slow walkers, an average RMSE of 2.5 steps/min, 0.04 m, and 0.10 m/s were respectively achieved for cadence, step length, and speed estimation. For normal walkers, the errors were 3.5 steps/min, 0.08 m, and 0.12 m/s. An average RMSE of 1.3 steps/min, 0.05 m, and 0.10 m/s were also observed on fast walkers. For people using walking aids, the error significantly increased up to an RMSE of 14 steps/min, 0.18 m, and 0.27 m/s. The results demonstrated the robustness of the proposed combined speed estimation approach for different speed ranges. It achieved an RMSE of 0.10, 0.18, 0.15, and 0.32 m/s for slow, normal, fast, and using walking aids, respectively.

A probabilistic model to investigate the properties of prognostic tools for falls.

BACKGROUND: Falls are a prevalent and burdensome problem in the elderly. Tools for the assessment of fall risk are fundamental for fall prevention. Clinical studies for the development and evaluation of prognostic tools for falls show high heterogeneity in the settings and in the reported results. Newly developed tools are susceptible to over-optimism. OBJECTIVES: This study proposes a probabilistic model to address critical issues about fall prediction through the analysis of the properties of an ideal prognostic tool for falls. METHODS: The model assumes that falls occur within a population according to the Greenwood and Yule scheme for accident-proneness. Parameters for the fall rate distribution are estimated from counts of falls of four different epidemiological studies. RESULTS: We obtained analytic formulas and quantitative estimates for the predictive and discriminative properties of the ideal prognostic tool. The area under the receiver operating characteristic curve (AUC) ranges between about 0.80 and 0.89 when prediction on any fall is made within a follow-up of one year. Predicting on multiple falls results in higher AUC. CONCLUSIONS: The discriminative ability of current validated prognostic tools for falls is sensibly lower than what the proposed ideal perfect tool achieves. A sensitivity analysis of the predictive and discriminative properties of the tool with respect to study settings and fall rate distribution identifies major factors that can account for the high heterogeneity of results observed in the literature.

[Overdosing on diltiazem in heptic insufficiency]. / Sovradosaggio del diltiazem in presenza di insufficienza epatica.

In a patient with hepatic failure of middle grade diltiazem at standard therapeutic dosis for unstable angina caused collateral fuss on atrioventricular conduction. This event is not considered in medical literature or on the schedule of the product. Because of the pharmacokinetics features of diltiazem, a higher risk of side effects can be expected if a abnormality of hepatic function is present.

[Ebstein's anomaly in adult patients: diagnostic and prognostic profile with regard to two cases (author's transl)]. / L'anomalia di Ebstein nell'eta' adulta. Rilievi diagnostici e prognostici a proposito di due osservazioni.

Two cases of Ebstein's anomaly in apparently asymptomatic adult patients are described. The chances of non invasive recognition of the malformation by means of electro-vectorcardiography and echocardiography are discussed. Unlike their useful diagnostic contribution, their prognostic valve seems to be negligible. For this purpose clinical course of malformation would remain very important, even if some unusual electrocardiographic and radiological features can provide interesting informations.