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Start Over Author "Andreas Caduff" Journal diabetes technology & therapeutics
2 results on '"Andreas Caduff"'

1. Impact of Posture and Fixation Technique on Impedance Spectroscopy Used for Continuous and Noninvasive Glucose Monitoring

Author

Andreas Pfützner, Thomas Forst, Andreas Caduff, Thomas W. Schrepfer, and Martin Larbig

Subjects
Adult, Blood Glucose, Male, medicine.medical_specialty, Time Factors, Supine position, Endocrinology, Diabetes and Metabolism, Arbitrary unit, Posture, Monitoring, Ambulatory, Cutaneous microcirculation, Microcirculation, Endocrinology, Forearm, Reference Values, Laser-Doppler Flowmetry, Supine Position, medicine, Humans, Skin, Fixation (histology), business.industry, Erythrocyte Membrane, Blood flow, Dielectric spectroscopy, Surgery, Medical Laboratory Technology, medicine.anatomical_structure, Female, business, Biomedical engineering
Abstract

Impedance spectroscopy allows for the assessment of changes in the permittivity and conductivity of erythrocyte cell membranes, induced by blood glucose variations. This study was performed to evaluate the potential influence of motion-induced microvascular blood flow variations from different forearm postures on the PENDRA (Pendragon Medical AG, Zürich, Switzerland) signal. Fifteen volunteers without diabetes were included (seven female, eight male, mean +/- SD age 33.3 +/- 9.9 years, body mass index 24.8 +/- 3.0 kg/m(2)). PENDRA devices were fixed at both upper extremities with different fixation techniques (bracelet and adhesive tape). Standardized position changes of the upper extremities were performed to induce variations in cutaneous microcirculation, which were assessed by laser-Doppler-fluxmetry with different probe temperatures on the forearm. Changes in microcirculation were seen in some of the different motion procedures: supine to hanging, 61.1 +/- 29.9 arbitrary units (AU) to 46.2 +/- 24.8 AU at 37 degrees C and 15.9 +/- 13.0 AU to 13.4 +/- 10.1 at skin temperature (P0.01 for both probes); supine to upright, 80.5 +/- 55.4 AU to 74.9 +/- 43.8 AU (not significant) at 37 degrees C and 18.7 +/- 16.8 AU to 20.9 +/- 16.1 AU at skin temperature (P0.01). An initially observed subtle influence of microcirculation variations on the impedance signal was minimized when the device was fixed by both bracelet and tape. Other influencing factors (such as temperature, local anatomy, etc.) are addressed in the complex calibration procedure. Well-educated patients might be the best candidates for first using the device for continuous glucose monitoring. They may especially benefit from the trend indication and the hypoglycemia/hyperglycemia threshold and alarm functions.

Published
2004

2. Cutaneous Blood Perfusion as a Perturbing Factor for Noninvasive Glucose Monitoring.

Author

Andreas Caduff, Mark S. Talary, and Pavel Zakharov

Subjects
*BLOOD sugar monitoring, *DIABETES, *SYSTEMATIC reviews, *PERFUSION, *ELECTROMAGNETISM in medicine, *NONINVASIVE diagnostic tests
Abstract

AbstractIt is widely accepted that noninvasive glucose monitoring (NIGM) has the potential to revolutionize diabetes therapy. However, current approaches to NIGM studied to date have not yet demonstrated a level of acceptable functionality to allow real-time use, beyond restricted fields of application. A number of reviews have been devoted to the subject of NIGM with different focuses related to challenges and a description of the respective underlying problems. This review is aimed at addressing a fundamental topic in the application of NIGM that seems to have received less attention, by describing the perturbations that result in a reduced functionality of NIGM in daily use. Here we provide a short general introduction to glucose monitoring and a basic illustration of the electromagnetic spectrum with a description of the respective physical mechanisms underlying the measurement techniques. This allows for a better understanding of how these perturbing factors affect the measured properties. Cutaneous blood perfusion is one of the major perturbing factors to NIGM, along with variations in temperature, migration of water, and the effect of attachment of the sensor to the skin. An understanding of the mechanisms underlying perfusion variation over time and within the measured human skin tissue matrix is required to enable a discrimination between glucose-induced effects within the tissue and various biophysical impacts to be made. It is suggested that a plurality of probing frequencies is required to discriminate glucose-related changes from the perturbations. A system designed to perform the measurements in different regions of the electromagnetic spectrum with dedicated sensors (multisensor approach) has the potential to more efficiently and reliably discriminate glucose-related information from perturbations. This can be achieved by combining signals related to measurements with different physical underlying mechanisms of the interaction between the probing field propagation and the tissue to help account for the different sources of perturbations. [ABSTRACT FROM AUTHOR]

Published
2010
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