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- Andersson, Roger, 1967-, et al.
(författare)
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An asymmetric dialysis tube as an integrated part of a pressure-monitoring sensor
- 2001
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Ingår i: Technology and Health Care. - 0928-7329 .- 1878-7401. ; 9:5, s. 417-425
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Tidskriftsartikel (refereegranskat)abstract
- A sensor has been designed consisting of a tube holder with a force transducer and a tube with a modified cross-section. The holder has a lid that encloses the tube. By having a stiff holder and a compliant tube, the idea is that the intraluminal pressure in the tube can be obtained from the measured force. The method is intended for non-invasive pressure measurements in blood or dialysate tubes.We have used a tube cross-sectional geometry where the outer surface is elliptic and the inner surface is circular with a relation of 2:1 between the thinnest and thickest tube sides. The pressure transducer system shows a linear relationship between the applied pressure and the sensor output (r = 0.999). Within the temperature range, 32°–36°C, which corresponds to the blood and dialysate temperatures, the sensor accuracy is within ±0.8 kPa (±6 mm Hg). This indicates that the sensor should be clinically useful during dialysis and similar applications.
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- Andersson, Roger, 1967-, et al.
(författare)
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Cross-sectional changes in an asymmetric tube with bearing on non-invasive pressure measurements
- 2003
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Ingår i: Technology and Health Care. - 0928-7329 .- 1878-7401. ; 11:1, s. 11-20
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Tidskriftsartikel (refereegranskat)abstract
- This study aims at investigating the radial dimensional changes, as a result of an applied intraluminal pressure for an elastic tube with non-uniform cross section. The study is related to a method for non-invasive pressure measurement using the extracorporeal tube as part of the sensor. The intended application is for monitoring of pressure in the blood and dialysate tubes during haemodialysis. The intention is to find a tube cross-section geometry that results in an expansion of the tube so that it is suitable to use as a component in a pressure sensor. The tube should have high radial compliance and expand in a well-defined manner to be able to transfer the intraluminal pressure to a transducer element sensing the radial force. Radial expansion was studied experimentally for tubes with different cross-section geometries. For small tube expansions the resolution in the experimental measurements was not sufficient to study the radial expansion. In this case, numerical simulation was performed. We conclude that a tube with essentially elliptic outer surface and circular inner surface, with a relation of 1:2 between the size of the thin and thick wall, results in a radial expansion upon application of pressure indicating that this tube is suitable for use as part of a sensor.
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- Andersson, Roger, 1967-, et al.
(författare)
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Force to restore the shape of an asymmetric extracorporeal tube as the basis for non-invasive pressure measurements
- 2002
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Ingår i: International Journal of Artificial Organs. - 0391-3988 .- 1724-6040. ; 25:4, s. 281-289
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Tidskriftsartikel (refereegranskat)abstract
- A zero-balance principle is described where intraluminal pressure is estimated from the counter force needed to restore the tube shape of an elastic extra corporeal tube. The aim was to optimise cross-sectional tube geometry for tube expansion due to pressure and to reduce the sensitivity to variation in mechanical tube characteristics using an experimental statistical and factorial design. The main application is pressure monitoring in blood and dialysate tubes during hemodialysis. Improving the monitoring of the dialysis process will reduce complications, such as sudden decreases in systemic blood pressure or occlusion at the artero-venous fistula. The factorial design indicated strong influence from the geometrical characteristics of the tube as well from the geometrical design parameters of the pressure transducer. We found a consistent relationship between the intraluminal pressure and the applied force needed to restore the tube shape. The modified cross-sectional tube geometry enhances measurement sensitivity and facilitates the desired behavior of tubes during pressure applications.
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