Biological data observation apparatus

• US 20030109791A1
• Filed: 12/09/2002
• Published: 06/12/2003
• Est. Priority Date: 12/10/2001
• Status: Active Grant

• Current Assignee: Kabushiki Gaisha K -And- S
• Original Assignee: Kabushiki Gaisha K -And- S
• Inventors: Kondo, Shinji, Takemoto, Toru, Sakakibara, Noriaki, Honda, Toshihiro
• Granted Patent: US 6,953,435 B2
• Time in Patent Office: Days
• US Class Current: 600/500
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02108 from analysis of pulse wave characteristics
• CPC Class Codes: A61B 5/0285 Measuring or recording phase velocity of blood waves
• CPC Class Codes: A61B 5/4266 sweat secretion
• CPC Class Codes: A61B 5/4821 Determining level or depth of anaesthesia A61B5/1106 takes precedence

Abstract

A biological data observation apparatus includes a measuring unit including at least a photoelectric sensor including a light emitting element for emitting light with a predetermined wavelength onto a blood vessel of a subject and a light detecting element for detecting, as a photoelectric volume pulse wave, a change in an amount of transmitted or reflected light resulting from the light emitted from the light emitting section, a storage area in which pressure conversion data correlating a pulse wave area and a blood pressure value in order that the pulse wave area may be converted to the blood pressure value as an absolute value, the pulse wave area being obtained by integrating a wave form of the photoelectric capacity pulse wave per heartbeat, an operational unit calculating the pulse wave area on the basis of the photoelectric volume pulse wave obtained from the subject and further calculating the blood pressure value of the subject on the basis of the calculated pulse wave area and the blood pressure conversion data, and a display unit displaying a result of calculation performed by the operational unit.

Claims

1. A biological data observation apparatus comprising:

a measuring unit including at least a photoelectric sensor including a light emitting element for emitting light with a predetermined wavelength onto a blood vessel of a subject and a light detecting element for detecting, as a photoelectric capacity pulse wave, a change in an amount of transmitted or reflected light resulting from the light emitted from the light emitting element;

a storage area in which blood pressure conversion data correlating a pulse wave area and a blood pressure value in order that a pulse wave area may be converted to a blood pressure value as an absolute value, the pulse wave area being obtained by integrating a waveform of the photoelectric volume pulse wave per heartbeat;

an operational unit calculating the pulse wave area on the basis of the photoelectric volume pulse wave obtained from the subject and further calculating a blood pressure value of the subject on the basis of the calculated pulse wave area and the blood pressure conversion data; and

a display unit displaying a result of calculation performed by the operational unit.

2. An apparatus according to claim 1, wherein the blood pressure conversion data is calculated on the basis of a measuring artificial human body model including a liquid feeding unit pressure-feeding blood or an equivalent thereof per heartbeat time obtained while a sampling object having a predetermined form is in a rested state, the liquid feeding unit having a pressure adjustable in pressure feed, and a transfer tube through which the blood or equivalent thereof is transferred, the transfer tube having an inner diameter substantially equal to an inner diameter of a blood vessel of the sampling object near which blood pressure is measured by the photoelectric sensor while the object is in the rested state, a pressure measuring section measuring pressure of the blood or equivalent thereof in the transfer tube, and a photoelectric sensor irradiating light with a predetermined wavelength onto the transfer tube for detecting, as a photoelectric volume pulse wave, a change in an amount of transmitted or reflected light resulting from the irradiated light, and wherein the pressure applied to the blood or equivalent thereof during the pressure feed is varied into various values, and the photoelectric volume pulse wave and the pressure applied to the blood or equivalent thereof during the pressure feed are measured by the photoelectric sensor and the pressure measuring section respectively so that the pulse wave area per heartbeat time and the pressure value of the blood or equivalent thereof both obtained by the photoelectric sensor and the pressure measuring section respectively are correlated with each other.

3. An apparatus according to claim 2, wherein the measuring model has a flow rate measuring section measuring a flow rate of the blood or equivalent thereof per heartbeat time, the storage area stores flow velocity conversion data in which a flow velocity value obtained by dividing a flow velocity measured by the flow rate measuring section by a sectional area of the transfer tube, and the pulse wave area of the photoelectric volume pulse wave measured relative to the transfer tube, the flow velocity and the pulse wave area being correlated with each other, the measuring unit calculates a pulse wave area So on the basis of a photoelectric volume pulse wave obtained from the subject that is in a reference state prior to start of measurement, the measuring unit further calculating a reference pressure value Po and a reference flow velocity value Vo on the basis of the obtained pulse wave area So, blood pressure conversion data, flow velocity conversion data, the measuring model further calculating, from an algorithm, a blood pressure variation amount Δ

P indicative of a variation in a blood pressure in a predetermined time after calculation of the reference pressure value Po and the reference flow velocity value Vo on the basis of a change rate in a peak value of the photoelectric volume pulse wave and the reference flow velocity value Vo at the reference time, the algorithm being determined so that a flow velocity Vt at any time is calculated by substituting the flow velocity value Vo, a peak value Do of the photoelectric volume pulse wave, a peak value Dt of the photoelectric volume pulse wave at any time, and a constant k are substituted into equation (a) and the blood pressure variation amount Δ

P is obtained by substituting the reference flow velocity value Vo at the reference time, a flow velocity Vt at any time, and a blood density ρ

into equation (b);

Vt=(Do/kDt)²×

Vo  

 

(a) Pt−

Po=ρ

/2(Vo²−

Vt²)  

 

(b)

4. A biological data observation apparatus according to claim 3, wherein a plurality of the transfer tubes are provided having different diameters according to differences in individual subjects, the blood pressure conversion data and the flow velocity conversion data being calculated for each transfer tube, wherein the storage area stores a plurality of data tables so that the blood pressure conversion data and the flow velocity conversion data with respect to the transfer tubes with the different diameters are written into the data tables respectively, wherein the measuring unit includes a blood vessel diameter measuring section measuring a diameter of a blood vessel of the subject in a rested state in addition to the photoelectric sensor, and wherein based on results of measurement by the blood vessel diameter measuring section, the operational unit selects the data table storing the blood pressure conversion data and the flow velocity conversion data with respect to the transfer tube with the diameter approximate to the measured diameter of blood vessel of the subject.

5. A biological data observation apparatus according to claim 2, wherein the measuring unit further has another photoelectric sensor including a single light emitting element and a plurality of light detecting elements which are disposed along the blood vessel of the subject so as to be spaced each one from the other;

wherein the operational unit calculates a pulse wave area So on the basis of a photoelectric volume pulse wave obtained from the subject who is temporarily under the measuring reference state prior to measurement, further calculates a blood pressure value Po on the basis of the calculated pulse wave area So and the blood pressure conversion data, and still further calculates a flow velocity Vo in the measuring reference state on the basis of a phase difference between the photoelectric volume pulse waves obtained from the light detecting elements and distances between the light detecting elements;

wherein the operational unit calculates a flow velocity Vt in any period on the basis of a phase difference between the photoelectric volume pulse waves obtained from the light detecting elements and distances between the light detecting elements, and substitutes the flow velocity values Vo and Vt and the blood density ρ

for those in the equation (b) thereby to calculate a blood pressure variation amount Δ

P representative of variations in the blood pressure in any period;

Δ

P=Pt−

Po=ρ

/2(Vo²−

Vt²)  

 

(b)

and calculates the blood pressure value Pt in any period from the calculated blood pressure variation amount Δ

P and the blood pressure value Po at the measurement reference time.

6. A biological data observation system according to claim 3, wherein the measuring unit further includes a sweat amount measuring section measuring an amount of sweat given forth by the subject and a skin temperature measuring section measuring a temperature of a skin of the subject;

wherein the operational unit calculates a pulse wave area on the basis of the supplied the photoelectric volume pulse wave of the subject when the photoelectric volume pulse wave of the subject is supplied thereto, further calculating an amount of blood flowing in the subject on the basis of the calculated pulse wave area and the flow velocity conversion data and further calculates sweat amount conversion data correlating the amount of blood flowing and the sweat amount with each other from the calculated amount of blood flowing and the sweat amount measured by the sweat amount measuring section and skin temperature conversion data correlating the amount of blood flowing and the skin temperature with each other on the basis of the calculated amount of blood flowing and the skin temperature measured by the sweat amount measuring section, the sweat amount conversion and skin temperature conversion data being calculated for every subject; and

wherein the operational unit calculates mean values of the sweat amount and skin temperature of each subject on the basis of the sweat amount and skin temperature conversion data and the amount of blood of the subject without using the sweat amount and skin temperature measuring sections after the sweat amount and skin temperature data have been written into the storage area.

7. A biological data observation apparatus according to claim 6, wherein the storage area is written with body surface area conversion data which correlates personal form data including data of personal stature, weight, age, sex, and the like and data of body surface area with each other so that a body surface area of the subject is calculated;

wherein when at least one piece of personal form data regarding the subject has been supplied to the operational unit, the operational unit calculates a body surface area of the subject on the basis of the supplied personal form data and the body surface area conversion data, the operational unit further calculating calorie consumption required of the subject on the basis of the calculated body surface area or the skin temperature and a mean value thereof.

8. A biological data observation apparatus according to claim 3, wherein the storage area includes a waveform data storage section storing waveform data of the supplied photoelectric volume pulse wave, wherein the operational unit sets an allowed range the waveform data normally takes, based on the waveform data accumulated in the waveform data storage section,

wherein the operational unit determines whether new waveform data is within the allowed range upon supply of the waveform data thereto, and

wherein when part of the waveform data is out of the allowed range, the operational unit carries out a substituting process in which any waveform data is substituted for said part of the waveform data, said any waveform data being measured until the waveform data out of the allowed range has been detected from start of measurement and determined to be within the allowed range.

9. A biological data observation apparatus according to claim 8, wherein the operational unit calculates the allowed range on the basis of a period of past waveform data written onto the waveform data storage section.

10. A biological data observation apparatus according to claim 9, wherein in the substituting process, the operational unit calculates a mean waveform model on the basis of the periods and peak values of the waveform data measured until the waveform data out of the allowed range has been detected from start of measurement and determined to be within the allowed range.

11. A biological data observation apparatus according to claim 10, wherein the measuring unit includes a body motion sensor irradiating light having a wavelength shorter than a wavelength of the light irradiated by the photoelectric sensor in order to continuously detect an amount of light reflected on the skin surface of the subject, and the operational unit carries out a modifying process in which an output waveform of the body motion sensor is subtracted from an output waveform of the photoelectric sensor in order that a measurement error due to body motion of the subject may be eliminated.

12. A biological data observation apparatus according to claim 3, wherein in addition to the photoelectric sensor, the measuring unit further includes at least any one of:

a sweat amount measuring section measuring an amount of sweat given forth by the subject;

a skin temperature measuring section measuring a temperature of a skin of the subject;

an arterial oxygen saturation measuring section measuring an arterial oxygen saturation of the subject;

a heartbeat measuring section measuring a heartbeat of the subject; and

a brain wave measuring section measuring a brain wave of the subject;

wherein the operational unit calculates an anesthetic depth of the subject on the basis of primary biological data measured by the photoelectric sensor and said at least any one of the measuring section selected.

13. A biological data observation apparatus according to claim 12, wherein the storage area stores data of an algorism synthesizing different pieces of primary biological data so that a temporal transition is obtained, and the operational unit synthesizes a plurality of pieces of biological primary data obtained by the measuring unit, on the basis of the algorism, thereby calculating composite data A, the operational unit further selecting, as a reference value Ro, a value at a time approximately before or immediately after application of anesthesia from the calculated composite data A and compares a value At of the composite data A at a time after selection of the reference value Ao, thereby calculating an anesthetic depth.

14. A biological data observation apparatus according to claim 13, wherein the storage area stores data of change patterns of the composite data A, and when measurement of biological primary data of the subject is started after a time when the reference value Ao is to be selected, the operational unit collates a change pattern of composite data B based on said biological data with a change pattern of past composite data stored in the storage area thereby to extract similar composite data R and substitute the composite data B for a reference value Ro of the composite data R, the operational unit further calculating an anesthetic depth of the subject on the basis of the substituted reference value Ro and a value Bt of the composite data B.

15. A biological data observation apparatus according to claim 12, wherein the measuring unit includes the photoelectric sensor and the sweat amount measuring section, and the operational unit incorporates peak value data y1 of the photoelectric volume pulse wave obtained from the photoelectric sensor, heartbeat data y5 and sweat amount data y2obtained from the sweat amount measuring section thereby to calculate a mean value y1o of the peak value data in a predetermined period before application of anesthesia, a mean value y5o of the heartbeat data y5 in the predetermined period and a mean value y2o of the sweat amount data y2 in the predetermined period, the operational unit further obtaining a pulse-wave anesthesia depth T1 and a sweat amount anesthesia depth T2 from following equations (13) and (14) respectively on the basis of the mean values y1o, y5o and y2o and a value y1t of the peak value data y1 in a predetermined period after application of anesthesia, a value y5t of the heartbeat data y5 in the predetermined period and a value y2t of the sweat amount data y2, further calculating an anesthetic depth T (T=T1+T2) on the basis of the obtained pulse-wave anesthetic depth T1 and sweat amount anesthetic depth T2:

T1=(y1t×

y5t−

k1×

y1o×

y5o)/(k2×

y1o×

y5o)  

 

(13) T2=(y2t−

k3×

y2o)/(k4×

y2o)  

 

(14)

where k1, k2 and k3 are constants.

16. A biological data observation apparatus according to claim 3, wherein the operational unit calculates a cardiac output and arterial oxygen saturation on the basis of the photoelectric volume pulse wave obtained by the photoelectric sensor and blood pressure conversion data.

17. A biological data observation apparatus comprising:

a measuring unit including at least a blood pressure measuring section measuring a blood pressure value of a subject;

a storage area storing blood pressure and blood flow conversion data in which the blood pressure and an amount of blood flow are correlated with each other;

an operational section calculating a blood flow amount of the subject from a blood pressure value of the subject and the blood pressure and blood flow conversion data; and

a display unit displaying a result of calculation carried out by the operational section.