Surgery – Truss – Pad
Patent
1995-02-13
1997-10-28
Nasser, Robert
Surgery
Truss
Pad
126677, 126650, 126681, 126691, 126687, 126713, A61B 500
Patent
active
056808674
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an electronic blood pressure measurement device which detects the cuff pressure for the evaluation of vascular dynamics and is concerned in particular with an improved device for obtaining biological information besides blood pressure, etc. on the basis of pulse wave components extracted from the cuff pressure.
PRIOR ARTS
Conventional devices for non-invasive measurement of vascular dynamics include that which detects the Korotkoff's sound that is generated by the pulse waves within the blood vessels during the process of gradually decreasing the pressure of a pressurized cuff. In such a device, the pressures at the points in time at which the Korotkoff's sound is generated, becomes the maximum and disappears are detected to obtain the systolic blood pressure, the mean blood pressure and the diastolic blood pressure. However, detection errors occur easily in this method since the Korotkoff's sound is a minute sound in a frequency band that is easily influenced by external noise and this method has such problems as large detection errors and poor reproducibility since the decay of sound waves differ greatly according to the detected part and the thickness of the superficial tissue.
Thus, in recent years, the oscillometric method has come to be used in which the blood pressure, etc. are directly computed from the variations in the cuff pressure. In this method, the pulse waves that are overlaid onto the detected cuff pressure are extracted to derive the amplitudes of the pulse waves and the pressures at the points at which the pulse wave amplitude is the maximum, at which the amplitude is a predetermined proportion of the maximum value at the higher pressure side of the maximum and at which the amplitude is a predetermined proportion of the maximum pressure at the lower pressure side of the maximum are determined as the mean blood pressure, systolic blood pressure and diastolic blood pressure, respectively. Sphygmomanometers that use this method are not easily affected by external influences such as external noise and vibration and enable measurements of high accuracy and reproducibility since highly sensitive pressure sensors can be used and since the detected signals are in a low frequency band.
Most of the measurement devices of the said type perform only the detection of the systolic pressure, the diastolic pressure, the mean blood pressure and the pulse rate. However, since these values are influenced by various factors such as cardiac output and degree of hardening of the arteries and the influence of such factors cannot be judged by simply measuring the blood pressure, it is not only impossible to correctly evaluate the blood pressure value but it is also impossible to obtain a correct understanding of the vascular dynamics.
Also, particularly in the case of measurement devices using the oscillometric method, the blood pressure values are computed generally by a predetermined method that is based on comparison with a direct method such as that in which a catheter is inserted. However, such a method has a problem in that, due to variations in the pattern of pulse wave amplitudes, cases arise that do not correspond with values detected by the direct method.
Furthermore, the mechanism of generation of Korotkoff's sounds and pulse wave amplitudes has not been investigated in detail and the present circumstances are such that the relationships between measured data and the cause thereof are judged experientially and case by case.
The present invention is one that solves the said problems and the purpose thereof is to provide a measurement device that can extract information reflecting the vascular dynamics from pulse wave amplitude patterns on the basis of the knowledge obtained through the clarification of the mechanism of generation of pulse amplitudes to provide indications for such measured values as the blood pressure.
DISCLOSURE OF THE INVENTION
The present invention provides a pressure detection means (12, 16, 17:23) that detects the cuff press
REFERENCES:
patent: 4349034 (1982-09-01), Ramsey, III
patent: 4922918 (1990-05-01), Ruiter
patent: 5092343 (1992-03-01), Spitzer et al.
patent: 5339818 (1994-08-01), Baker et al.
patent: 5390679 (1995-02-01), Martin
patent: 5406952 (1995-04-01), Barnes
patent: 5533511 (1996-07-01), Kasperi et al.
Komatsu Masaru
Shimazu Hideaki
Shimizu Hidetaka
Yamaguchi Noriyuki
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