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Biomedical subjects

H B Bussmann

Publications and source records attributed to H B Bussmann.

4 recordsLinked to original sources
PubMed1998

Validity and reliability of measurements obtained with an "activity monitor" in people with and without a transtibial amputation.

BACKGROUND AND PURPOSE: In this study, the validity and reliability of measurements obtained with an "Activity Monitor" (AM) were examined. The instrument is designed to monitor ambulatory activity by use of accelerometer signals, and it detects several activities associated with mobility (standing, sitting, lying, transitions, movement-related activities). SUBJECTS: Four men with a transtibial amputation and 4 men without a transtibial amputation participated. METHODS: The subjects performed normal daily activities, during which accelerations were measured and videotape recording were made (reference method). Validity was assessed by calculating agreement scores between the AM output and the videotape recordings and by comparing the number of transitions and the duration of activities determined by both methods. RESULTS: The overall agreement between the AM output and the videotape recordings was 90%. Other agreement scores, in addition to the determination of the number of transitions and the duration of activities, were generally within a range of error of 0% to 10%. CONCLUSION AND DISCUSSION: The reliability and validity of the AM measurements appeared to be good, which supports its potential use in rehabilitation and physical therapy. [Bussmann HBJ, Reuvekamp PJ, Veltink PH, et al. Validity and reliability of measurements obtained with an "Activity Monitor" in people with and without a transtibial amputation.

Activities of Daily Living↗
PubMed1997

A novel tool to quantify physical activities: ambulatory accelerometry in psychopharmacology.

Accelerometry by means of body-mounted piezoresistive sensors was evaluated as a new method to quantify physical activities (body posture and physical and locomotor activity) in relation to the sedative and cardiovascular effects of benzodiazepines, in an ambulatory study. In a double-blind, randomized, crossover study, 12 healthy men received either an oral dose of 2 mg lorazepam, 0.5 mg alprazolam, 1 mg alprazolam, or a placebo on 4 different days. By means of a portable digital recorder, each day 4 hours of continuous measurements of accelerometer signals and heart rate were performed in a living room in the hospital. Changes in subjective sleepiness were assessed at the beginning, halfway, and at the end of the recording period. A separate validation study of the ambulatory environment was performed in three subjects, in which computer classification of activities based on accelerometry was compared with visual evaluation of simultaneously recorded videotapes. In our validation study, comparison of the computer classification with visual analysis based on videotapes revealed an overall agreement for spontaneous and standardized activities of 88% and 96%, respectively. In our pharmacological study, the subjects spent more time in the lying position (p < 0.01) and less time in the sitting position (p < 0.01) after benzodiazepine administration; the effects were strongest for lorazepam. Motility during static activities was reduced (p < 0.025), with motility after lorazepam administration being lowest. Both lorazepam and alprazolam (0.5 and 1 mg) increased subjective sleepiness (p < 0.01). On average , lorazepam induced an overall increase in mean heart rate of about 6%, whereas alprazolam reduced mean heart rate by 2% versus placebo (p < 0.01); the effects were not dependent on posture. The validation study showed that accelerometry forms a reliable method to quantify aspects of normal daily activities. Our pharmacological study revealed that quantification of body postures, physical activity, and motility by means of ambulatory accelerometry proves to be an objective and promising tool to evaluate the psychological and cardiovascular effects of (psycho) pharmaca in relation to the postural and mobility activities of normal daily life.

Adult↗
PubMed1996

Detection of static and dynamic activities using uniaxial accelerometers.

Rehabilitation treatment may be improved by objective analysis of activities of daily living. For this reason, the feasibility of distinguishing several static and dynamic activities (standing, sitting, lying, walking, ascending stairs, descending stairs, cycling) using a small set of two or three uniaxial accelerometers signals can be measured with a portable data acquisition system, which potentially makes it possible to perform online detection of static and dynamic activities in the home environment. However, the procedures described in this paper have yet to be evaluated in the home environment. Experiments were conducted on ten healthy subjects, with accelerometers mounted on several positions and orientations on the body, performing static and dynamic activities according to a fixed protocol. Specifically, accelerometers on the sternum and thigh were evaluated. These accelerometers were oriented in the sagittal plane, perpendicular to the long axis of the segment (tangential), or along this axis (radial). First, discrimination between the static or dynamic character of activities was investigated. This appeared to be feasible using an rms-detector applied on the signal of one sensor tangentially mounted on the thigh. Second, the distinction between static activities was investigated. Standing, sitting, lying supine, on a side and prone could be distinguished by observing the static signals of two accelerometers, one mounted tangentially on the thigh, and the second mounted radially on the sternum. Third, the distinction between the cyclical dynamic activities walking, stair ascent, stair descent and cycling was investigated. The discriminating potentials of several features of the accelerometer signals were assessed: the mean value, the standard deviation, the cycle time and the morphology. Signal morphology was expressed by the maximal cross-correlation coefficients with template signals for the different dynamic activities. The mean signal values and signal morphology of accelerometers mounted tangentially on the thigh and the sternum appeared to contribute to the discrimination of dynamic activities with varying detection performances. The standard deviation of the signal and the cycle time were primarily related to the speed of the dynamic activities, and did not contribute to the discrimination of the activities. Therefore, discrimination of dynamic activities on the basis of the combined evaluation of the mean signal value and signal morphology is proposed.

Activities of Daily Living↗