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| 2. |
- Ask, Per, 1950-, et al.
(författare)
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ECG Electrodes : A Study of Electrical and Mechanical Long-term Properties
- 1979
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 23:2, s. 189-206
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Tidskriftsartikel (refereegranskat)abstract
- The long-term properties of commercially available ECG-electrodes were studied by investigating the parameters: polarization potential, electrical impedance, adhesion, and skin reactions during a period of 7 days. As expected, the most stable polarization potentials were obtained for Ag/AgCl electrodes. Certain simple disposable electrodes showed large polarization potential variations. The most stable electrode impedance was obtained for disposable electrodes with stable adhesion and equipped with an electrode cup or similar. Unchanged adhesion and mechanical properties during the test period were shown by the disposable electrodes with a large self-adhesive collar.
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| 3. |
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| 4. |
- Ask, Per, et al.
(författare)
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Frequency content of esophageal peristaltic pressure.
- 1979
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 236:3, s. E296-300
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Tidskriftsartikel (refereegranskat)abstract
- Fourier analysis of esophageal peristaltic pressure waves was performed by computer fast Fourier transform. The highest power spectral density was obtained in the frequency range below 1 Hz. The Fourier analysis showed spectral components up to about 12 Hz in the upper esophageal sphincter (UES). The significance of different frequency components was investigated by low-pass filtering at different cut-off frequencies. A reduction in the amplitude of UES contractions was obtained at a cut-off frequency of 4 Hz, whereas the cut-off frequency of 8 Hz did not show any distortion. For perfused manometry systems, only a low-compliance perfusion pump will have sufficient bandwidth for accurate recording of esophageal peristaltic pressures.
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| 6. |
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| 7. |
- Ask, Per, et al.
(författare)
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Pressure integrating transducer for oesophageal manometry.
- 1979
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Ingår i: Medical and Biological Engineering and Computing. - 0140-0118 .- 1741-0444. ; 17:3, s. 360-364
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Tidskriftsartikel (refereegranskat)abstract
- A transducer has been designed that gives an integrated measure of the radial pressure profile at a specific level in the oesophagus. The oesophageal pressure is picked up by a semicylinder elastically connected to a transducer housing by means of a slotted semicylinder. The displacement of the semicylinder is sensed by a semiconductor transducer element. The transducer has a linear relation between static pressure and output voltage, flat frequency characteristic and low temperature drift.
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| 8. |
- Ask, Per, et al.
(författare)
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Static and dynamic characteristics of fluid-filled esophageal manometry systems
- 1977
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Ingår i: American Journal of Physiology. - 0002-9513. ; 233:5, s. E389-E396
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Tidskriftsartikel (refereegranskat)abstract
- Esophageal manometric systems with water-filled catheters have been characterized by the use of model experiments. The examined parameters have been: catheter dimension, catheter compliance, catheter resistance, pump type, pump compliance, and perfusion flow. Accurate static pressure measurements have been obtained for perfused systems independently of the investigated parameters. The dynamic characteristics vary with catheter diameter and perfusion flow. For catheters with low diameter, a narrow bandwidth is obtained for the investigated perfusion flows. The results have been expressed in terms of an electric model of the measurement system. Perfusion pumps with low compliance are recommended to improve the dynamic properties of the measurement system.
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