| Project/Area Number |
17590758
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Circulatory organs internal medicine
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| Research Institution | Yokohama City University |
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Principal Investigator |
TOCHIKUBO Osamu Yokohama City University, Medicine research course, Professor (30046099)
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| Co-Investigator(Kenkyū-buntansha) |
UMEMURA Satoshi Yokohama City University, Medicine research course, Professor (00128589)
EIMURA Kazuo Yokohama City University, Attached hospital, Professor (90214866)
OOSHIGE Keryi Yokohama City University, Department ofMedicine, Associate professor (50343398)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,540,000 (Direct Cost: ¥3,300,000、Indirect Cost: ¥240,000)
Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Blood Pressure Monitoring / Hypertension Circulation / Information Communication Technology / Internal medicine / Social medicine |
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| Research Abstract |
A very small continuous blood-pressure monitor (CBPM) in the style of an earpiece situated in the cephalic area, where the tragus and the ear orifice are located, produces continual blood-pressure measurements more easily than a brachial device. Its location employs the proximity to the brain of the antilobium and the ear orifice, near which runs the superficial temporal artery (the anastomosis of the infernal artery). Furthermore, since this part of the body moves less vigorously than the upper arm, blood-pressure measurements made with this device impede action less. Owing to clear positional relations between cephalic blood pressure (BPc) and brachial blood pressure (BPb) and the heart (hydrostatic-pressure difference between the two is h), measurements made in this region are easy to evaluate theoretically: relations between the two- BPb= a ×BPc+ h (a=ratio to arterial diameter; h=hydrostatic pressure).
With the CBPM, an earpiece outfitted with a small cuff housing a small photoelec
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tric sensor tube is positioned in the region of the ear opening. Together, this small cuff and a small cuff at the external antilobium apply pressure to the superficial temporal artery. A micro-pump regularly pressurizes the cuff. A microcomputer analyzes the pulse-wave patterns observed by the photoelectric tube and arterially caused cuff-oscillation and automatically computes and records systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR).
Improvements to the device facilitate attachment at the ear opening take accuracy and practicality into consideration. Even when corrected by h, both SBP and DBP decreased by an average of 80% in comparison with brachially measured blood pressure. Correlation was high (r>0.80) , and it is thought that changes in relative blood pressure can be measured.
Weighing only a few grams, the earpiece causes no more discomfort than a hearing aid and is therefore less burdensome than ordinary brachial devices for measuring ambulatory blood-pressure. In addition to better attachment, revisions have improved the way the photoelectric tube collects arterial pulse-data.
Research is now proceeding toward making possible continuous (beat-by-beat) BP measurements inside the tragus. To this end, we make use of a subminiature laser-Doppler blood flow (BF) meter developed by the NTT MI Laboratory. Since blood pressure is expressed as the product of blood flow and systemic vascular resistance R (BP=BF x R), stabilizing R makes continuous BP measurement possible. R is regulated by arteriolar caliber (proportional to the amount of oxidized hemoglobin in the tragus). We therefore attempted to stabilize R and make continuous BP measurements by measuring tragal oxidized hemoglobin and using a cuff to apply air pressure to determine tissue oxidized hemoglobin (actually a measurement of light absorbance). We are currently investigating ways to make the system more practical. Less
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