| 1. |
- Ask, Per, et al.
(författare)
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Effect of time interval between swallows on esophageal peristalsis.
- 1980
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Ingår i: American Journal of Physiology. - 0002-9513 .- 2163-5773. ; 238:6, s. G485-90
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Tidskriftsartikel (refereegranskat)abstract
- Esophageal peristaltic pressure amplitude, peristaltic incidence, speed of peristalsis, and wave duration were investigated as a function of swallow interval. In the distal half of the esophagus, the amplitude decreased at swallow intervals of 8 s and shorter. At intervals of 8 and 4 s, dropouts of contractions that were obtained were most frequent in the distal esophagus and for the 4-s interval. At continuous swallows no contractions were obtained below the upper esophageal sphincter until the end of the swallow sequence, after which a peristaltic wave of high amplitude propagated along the esophagus. The peristaltic speed increased toward a level 5 cm above the lower esophageal sphincter. The peristaltic wave duration was approximately the same in different parts of the esophagus and at different swallow intervals. The findings indicate an impairment of esophageal transport function by short swallow intervals.
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| 2. |
- Ask, Per, et al.
(författare)
-
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
-
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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| 3. |
- Ask, Per, et al.
(författare)
-
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
-
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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