| Summary: | 碩士 === 中原大學 === 醫學工程研究所 === 89 === Abstract
This research investigated the relationship between heart rate variability (HRV) and orthostatic hypotension of spinal cord injury patients at varied tilting angle controlled by tilting table. In order to clarify the mechanism of postural hypotension and to predict the timing of syncope, we monitored the changes of blood pressure and heart rate.
We studied 14 normal subjects (7 male :24 ±3 years, 7 female: 22 ±1 years) who have no history of either cerebrovascular or cardiovascular diseases and 9 patients (7 Frankel A∼B :30 ±14 years , 2 Frankel C∼D: 47 ±3 years) with spinal cord injury above T6. A 30-minute head-upright tilt test was conducted on all subjects. We set five tilting angle ( 0°、30°、45°、60°、75°) in our study , and each angle stayed 6 minutes. We analyzed the time and frequency (0.04 ~ 0.4Hz) domain of the heart rate variability in all subjects.
The results of our study suggested that the syncope would occur when the systolic or diastolic blood pressure decreased more than 20mmHg and the RR interval —LF (Low frequency) increased over 50% simultaneously in spinal cord injury patients with postural hypotension. Blood pressure plays a dominant role in evaluating syncope. We suggest that parameter of heart rate and RRI-LF index can also be the reasonable indicators to predict the syncope in our study.
Key Word: Heart rate variability、tilting table、Orthostatic hypotension、Spinal cord injury
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