2007 Fiscal Year Final Research Report Summary
Development of Noninvasive Artificial Baroreflex System for Severe Orthostatic Hypotension
| Project/Area Number |
18300172
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Medical systems
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| Research Institution | Kochi University |
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Principal Investigator |
YAMASAKI Fumiyasu Kochi University, University Hospital, Assistant Lecturer (10243841)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Takayuki Kochi University, School of Medicine, Professor (90205930)
KAKINUMA Yoshihiko Kochi University, School of Medicine, Associate Professor (60265866)
ARIKAWA Mikihiko Kochi University, School of Medicine, Assistant Lecturer (20432817)
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| Project Period (FY) |
2006 – 2007
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| Keywords | Advanced device / Biomedical Engineering / Orthostatic Hypotension / Baroreflex / Noninvasive Therapeutic System |
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| Research Abstract |
Baroreflex failure due to progressive neurodegenerative diseases in middle age and elderly induced severe orthostatic hypotension and syncope. However, commonly used intervention can not restore the function and most affected patients remain bedridden. Therefore, we developed noninvasive artificial baroreflex system with clinical investigation for two years.
1. Estimation of baroreflex open-loop function : The open-loop transfer function of Hnative(f) estimated by comparing autonomic failure patients to normal subjects showed low-pass characteristics with a cut off frequency of 0.01Hz. The steady-state gain at the lowest frequency was 5.3.
2. Estimation of transfer function of HSTM-SAP(f) from abdominal pants pressure to arterial pressure (AP) : Averaged step response function in patients with autonomic failure showed rapid AP response to 90% of steady state by abrupt increase of pants pressure. The steady-state gain at the lowest frequency was 0.7±0.3 mmHg/mmHg.
3. Design of artificial vasomotor center : The instantaneous AP response to pants pressure was numerically simulated with the averaged HSTM-SAP(f). Based on these results, proportional correction factor of Kp was set at 0.4, and integral correction factor of Ki was set at 0.2, so that the system could quickly and effectively attenuate the effect of the AP decline. The system was leaded the artificial vasomotor center with these correction factors.
4. Setting up of the system and clinical application : The devise was composed of PC with the vasomotor center, AP monitor, solenoid control valve, compressed air cylinder and abdominal air pants. A sudden tilting produced a rapid progressive fall in AP of approximately 20 mmHg, when the system was activated, the AP fall was attenuate the drop in AP of 11mmHg.
5. Possibility of AP control with a thigh and lower leg cuff A step response function showed rapid AP response to the steady state by abrupt increase of cuff pressure in 20 seconds.
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