CN1076348A - Instrument for measuring blood pressure - Google Patents

Abstract

The invention discloses a kind of instrument for measuring blood pressure, it contains prestage (14), venous pressure test circuit (12), signal processor (20), heart rate detector (28) and data display equipment (22).Described signal processor (20) is made up of peak holding circuit (1), valley hold circuit (2), mean value operating circuit (3).Described peak holding circuit (1) is in order to obtain the peak signal that characterizes systolic pressure, and described valley hold circuit (2) is in order to obtain the valley signal that characterizes diastolic pressure, and described mean value operating circuit (3) is in order to calculate mean arterial pressure.

Description

Instrument for measuring blood pressure

The invention relates to the instrument that blood pressure detects.It is specially adapted to the monitoring of blood pressure of critical patient and thoracic surgery etc.

For a long time, blood pressure measuring instrument commonly used is Baden's tubular type sphygomanometer or mercury sphygmomanometer in the hospital.The shortcoming of these sphygomanometers is that precision is low, response speed is slow.

In recent years along with the development of electronic technology, sensing technology, people develop a series of novel blood pressure measuring instruments, these instruments utilize pressure transducer directly to experience blood pressure, and the signal of telecommunication that pick off is exported amplifies, handles, and show with numeral or image then.For example U.S. Datascope company releases a kind of multi-functional detecting instrument, and it contains amplifier, wave filter, high-precision a/d converter, memorizer, single chip microcomputer, display etc.This instrument adopts microprocessor processes, and is multiple functional, not only can detect blood pressure, heart rate, but also take temperature, electrocardio, breathing etc.But this instrument costs an arm and a leg, and very flexible, owing to adopt software, maintenance is inconvenient.

The objective of the invention is to overcome weak point in the prior art, a kind of simple in structure, cheap, instrument for measuring blood pressure device of using flexibly, being convenient to keep in repair is provided, this instrument does not use microcomputer just can accurately measure the basic physiological parameter of blood pressure.

The present invention contains prestage (14), in order to signal of telecommunication Uaps, venous pressure test circuit (12), signal processor (20), heart rate detector (28), the data display equipment (22) of the arteriotony that has amplified to be provided.Described signal processor (20) connects prestage (14); Described data display equipment (22) connects data processor (20), heart rate detector (28), venous pressure test circuit (12) respectively.Described signal processor (20) is made up of peak holding circuit (1), valley hold circuit (2), mean value operating circuit (3).Described peak holding circuit (1) is in order to obtain the crest voltage Us that characterizes systolic pressure, and it connects the controller in prestage (14), mean value operating circuit (3), the data display equipment (22) respectively.Described valley hold circuit (2) is in order to obtain the valley point voltage Ud that characterizes diastolic pressure.It forms circuit (6), sampling hold circuit (4) etc. by valley value detection circuit (5), sampling pulse and forms.Described valley hold circuit (2) connects the controller in prestage (14), mean value operating circuit (3), the data display equipment (22) respectively.Described mean value operating circuit (3) is in order to calculate mean arterial pressure Um, described Um=1/3(Us+2Ud), it connects data display equipment (22).

Data display equipment of the present invention (22) can adopt following design.It comprises: controller (26), multi-way switch circuit (24), A/D converter (34), intervalometer (38), data register (36), enumerator (39), data-out port (43), light-emitting diode display (44).Described controller (26) is used to produce reset signal, the variable connector signal of signal processing, the enabling signal of A/D; It connects signal processor (20), multi-way switch circuit (24), A/D converter (34) respectively.Described multi-way switch circuit (24) is made of one group of four path analoging switch, and it connects signal processor (20), venous pressure test circuit (12), data register (36), A/D converter (34) respectively.Described A/D converter (34) also connects data register (36), intervalometer (38).Described counting connects heart rate detector (28), intervalometer (38), data register (36) respectively according to (39).Described data-out port (43) and LED charactron display (44) connect data register (36) and intervalometer (38) respectively.

Heart rate detector of the present invention (28) can adopt by wave filter (80), attenuator (82), the circuit of averaging (78) and comparator A8 and constitute.

Valley value detection circuit among the present invention (5) is formed anti-phase and level compensation circuit by operational amplifier A 5, resistor R 6-R11 and potentiometer W, with so that the signal inversion of Uaps, and the DC level that superposes; Described valley value detection circuit (5) also comprises the peak detection circuit that operational amplifier A 6, A7, diode D2, resistor 12, capacitor C2, switch S 2 are formed, and is used to detect the time that valley occurs.

Sampling pulse among the present invention forms circuit (6) can adopt monostable trigger.

Controller among the present invention (26) can comprise agitator OS, four phase clock generators of the long period short spacing that monostable trigger (60), (61), (62), XOR gate (64), (65), NAND gate (66) constitute, the A/D enabling gate signal circuit that monostable trigger (68) forms, the switch controlling signal that shift register (74) forms produces circuit, the reset signal generating circuit that NAND gate (72), monostable trigger (70) constitute.

The invention will be further described below in conjunction with drawings and Examples.

Fig. 1 is the block diagram of instrument for measuring blood pressure of the present invention;

Fig. 2 is the block diagram of signal processor (20);

Fig. 3 is the electrical schematic diagram of signal processor (20);

Fig. 4 is the main oscillogram of signal processor (20);

Fig. 5 is the electrical schematic diagram of controller (26) and switch (24);

Fig. 6 is the main oscillogram of controller (26) and switch (24);

Fig. 7 is the theory diagram of heart rate detector (28);

Fig. 8 is another embodiment theory diagram of data display equipment (22).

In the drawings, (10) are the input port from the arterial pressure transducer signal, and (11) are the input port from the venous pressure sensor signal, and described pick off can be selected pull spring formula or piezoresistive silicon sensor for use.Pick off converts arteriotony and venous pressure to the corresponding signal of telecommunication respectively.For the sensitivity that improves pick off with reduce common mode disturbances, pick off adopts the output of differential type balance.

Send into amplifier (16) from the output signal of arterial pressure pressure transducer.This amplifier adopts the differential input amplifier of high-gain and high cmrr, and its gain is about 50dB, and common mode rejection ratio is about 80dB.Deliver to wave filter (18) and heart rate detector (28) respectively through the signal (17) that amplifier (16) has amplified.Wave filter (18) is selected three rank active low-pass filters for use in order to filter noise and interference, and its bandwidth is about 40Hz.Heart rate detector (28) is in order to detect heart rate pulse HR (29).Amplifier (16) and wave filter (18) have been formed prestage (14).

Heart rate detector (28) is by formations such as wave filter (80), attenuator (82), the circuit of averaging (78) and comparator A8, and its connected mode as shown in Figure 7.

Deliver to circuit of averaging (78) and wave filter (80) respectively from the signal (17) of amplifier (16).The circuit (78) of averaging takes out the meansigma methods of signal (17), obtains one and changes with the peak valley difference and gradual change signal very stably.It is the active low-pass filter of 5Hz that described wave filter (80) adopts cut-off frequency, higher hamonic wave in its filtered signal and interference, what export is the signal (81) that only reflects fundamental frequency, and it wants much smooth than the waveform of original signal (17), and amplitude is approximate.In order to guarantee heart rate pulse of the stable generation of each cardiac cycle, through the decay of attenuator (82) dividing potential drop, make its peak value exceed average signal slightly signal (81).Then, the signal to mean signal after the decay compares in comparator A8, thereby obtains very stable heart rate pulse, counts as heart rate with it, just can be by determining heart rate in the arterial pressure signal (17) exactly.The heart rate pulse that is detected is sent to enumerator (39).

Through the filtered signal of wave filter (18) is the pulsating volage that characterizes blood pressure, i.e. arterial pressure signal Uaps (19).This signal is delivered to signal processor (20) and is handled.Signal processor (20) is got its crest voltage Us with peak holding circuit (1) from Uaps, characterize systolic pressure, gets its valley point voltage Ud with valley hold circuit (2), characterizes diastolic pressure.And utilize mean value operating circuit (3) to calculate, thereby obtain mean arterial pressure Um.

Signal processor (20) is to carry out work under the control signal effect that controller (26) is sent here.Controller (26) makes signal processor (20) and switch (24), A/D converter (34), data register (36), display co-ordinations such as (44).

Send into amplifier (30) in the venous pressure test circuit (12) from the output signal of venous pressure pressure transducer.Because the signal of venous pressure is very faint, so amplifier (30) must have higher gain and higher common mode rejection ratio than arterial pressure amplifier (16).Present embodiment adopts gain 68dB, common mode rejection ratio 100dB.For the venous pressure signal of telecommunication can use same A/D converter with the arterial pressure signal of telecommunication, the gain of venous pressure amplifier (30) must be formulated to consistent with the output coordinating of arterial pressure amplifier (16), be that A/D is output as 240 yards (BCD), corresponding venous pressure is 24.0cmH ₂O, arterial pressure is 240mmHg.Arterial pressure amplifier (16) and venous pressure amplifier (30) all adopt typical instrument amplifying circuit form, promptly are input as two homophase amplifier stages, and the second level is differential amplification.

Venous pressure is generally very little normal pressure, but occurs faint negative value sometimes.Because A/D converter (34) adopts the one-way only operation mode, so must insert one-level absolute value amplifier (32) afterwards at venous pressure amplifier (30).Described absolute value amplifier (32) comprises polarity decision circuitry, analog switch and unit see-saw circuit (being K=-1).When negative pressure occurring, the output of decision circuitry control analog switch, with the outfan of unit see-saw circuit access absolute value amplifier (32), its output equates with the vacuum magnitude that amplifier (30) transports, opposite in sign, becomes positive voltage.Therefore, no matter venous pressure is just or negative, absolute value amplifier (32) always output Uv on the occasion of.Meanwhile, " bearing " signal of its output is fed to display (44), to change the symbols displayed position.

The Uv of venous access output and Us, Ud, the Um of arterial channel deliver to multi-channel switcher (24) simultaneously, and flow to A/D converter (34) successively, convert analog quantity to digital quantity.

Described A/D converter (34) is advisable to adopt single bevel.The single bevel A/D converter contains ramp generator, comparator, enumerator and clock circuit etc.Conversion and control is finished by a gate signal, and this gate signal is come the control signal of self-controller (26).Enumerator adopts binary-decade counter, directly obtains binary-coded decimal.The present invention adopts the ramp generator of constant-current source type, can improve the linearity on slope greatly, and the nonlinearity erron that makes A/D converter (34) satisfies test request less than 1%.A/D converter (34) is output as three binary-coded decimals of 12 lines of time-division.

Intervalometer (38) also will export one group of clock signal-five tunnel control signal and go to control display (44) work, thereby the circulation that realizes five groups of data shows except providing the clock for A/D converter (34).

Tremulous pulse voltage signal after amplifier (16) amplifies is delivered to heart rate detector (28) and is located.Isolated heart rate pulse signal (29) is delivered to enumerator (39) and is carried out 1 minute counting, promptly gets the data of heart rate.The gate of described enumerator (39), control signal such as reset are all come self-timer (38).

Data register (36) comprises five groups of depositors and corresponding latch controllers.The heart rate data that four groups of data sum counters (39) that it sends A/D converter (34) here are sent here, be latched in the depositor respectively according to sequential, so that five groups of data outputs successively under the timing controling signal effect, deliver to display (44) and data-out port (43), realize that five circulations show.

From latching of four groups of data of A/D converter (34) is the pass gate signal that is produced when the each A/D EOC, through time-delay, and lock down in four road gate-control signals control that controller (26) produces, finish data converted and in time lock in the corresponding registers thereby make.Because heart rate data is from Cardiotacs (39) independently, thus it latch only synchronously with the reset signal of enumerator (39), and be the leading reset signal.The output of data register (36) is five groups of loop-around datas of time-division, these group data outputs (42) are combined into data-out port (43) with five road timing controling signals (45) that intervalometer (38) produces, it is connected with display (44), is the groundwork signal of outer display screen.

Display (44) contains driver, decoder, five groups of three LED charactrons, sign bit, heart rate display lamp etc.The output of decoder still is that five circulation show sign indicating number for seven sections.Circulation shows five tunnel control signals (45) control that produced by intervalometer (38).

As the needs monitoring, can add warning system (46), it contains finite value preset device (50), selector switch (52), magnitude comparator (48), audible-visual annunciator (54) etc.When needs are guarded, can set up this warning system.

Signal processor (20) and controller (26) are core contents of the present invention, are further described below.

In signal processor (20), be transported to the in-phase end of the A1 of peak holding circuit (1), the negative circuit input R7 of valley hold circuit (2), the signal input part of sampling hold circuit (4) simultaneously from pressure transducer and through the blood pressure signal Uaps (19) of amplification and filtering.

The output voltage U s of the peak holding circuit of being made up of A1, A2, D1, C1, R1, S1 (1) rises along with the rising of Uaps, and after rising to first summit, Uaps begins to descend, and Us then keeps former peak value, and does not descend.When Uaps rises and during greater than first peak value, Us follows the rising of Uaps once more and rises once more.As long as Uaps is less than Us, Us just keeps the maximum of Uaps, and peak value as shown in Figure 4 keeps waveform Us.When controller (26) sent reset signal for peak holding circuit (1), peak value Us was just as characterizing systolic pressure output.

The cycle of reset signal also is the collection period of data.The length in cycle requires to decide according to medical treatment, is advisable second with 3-4 usually.The pulse width of reset signal then is advisable with about 1 millisecond.

The R7 of Uaps in valley hold circuit (2) is added on the A5, anti-phase and the level compensation circuit that is made of A5 etc. is with the Uaps signal inversion, make its spike become low ebb, paddy originally becomes the peak, giving this signal stack a DC level by level compensation circuit again, is positive level with the spike point that guarantees inversion signal.In described anti-phase and level compensation circuit, A5 is actually an add circuit, and its of input is the Uaps from R7, and another is the negative voltage that gets from R6, W, R8 dividing potential drop, through the A5 summation, obtains anti-phase DC compensation.W divide the DC level of affects output of negative voltage, therefore,, must guarantee that the anti-phase peak point of signal afterwards is greater than zero level to the adjusting of W.For guaranteeing correct work, preferably whole waveform is all moved on to more than the zero level.

Signal after anti-phase and level compensation is delivered to the peak detection circuit that A6, A7 etc. form.The peak detection circuit that A6, A7 etc. form, the structural similarity of the peak holding circuit of forming with A1, A2 etc., but it is not the maximum that is used for obtaining signal the peaked moment occurs but be used for detecting.That is to say, (see figure 4) when first valley point appears in Uaps, the outfan of A6 produces downward transition rapidly, and keeps this low level, occurs being lower than first valley point once more up to Uaps, and A6 output is resetted.Along with the appearance of new valley point, the A6 outfan produces a downward transition again.Therefore, downward transition indicates the appearance of valley point.

Utilize downward transition to trigger sampling pulse and form circuit (6), what present embodiment adopted is monostable trigger.So monostable trigger just produces a burst pulse, promptly sampling pulse (57) deactivation sampling hold circuit (4) makes its work.When burst pulse arrived, sampling hold circuit (4) was just sampled, and after the pulse in the past, it just keeps the numerical value of sampling.

The input of sampling hold circuit (4) is Uaps (19), makes it utilize valley value detection circuit to detect the valley of sampling and catch Uaps in the valley point.After this valley occurs, if lower valley point does not appear in Uaps, just no longer include sampling pulse and produce, the output of sampling hold circuit (4) can not changed yet.Have only when Uaps has lower valley point to occur, sampling hold circuit (4) is just sampled once more and is kept, and arrives up to reset signal, and it just exports the minimum valley that maintains Uaps, i.e. Ud is as the output that characterizes diastolic pressure.

Reset signal (59) is from reseting signal controller (26), and the pulse width that its produces is that 1 millisecond, pulse period are 3-4 second.Before reset signal (59) arrived, gauge tap S1, S2, S3 were in open-circuit condition, thereby made peak, paddy holding circuit (1) and (2) be in the collecting work state.When reset signal (59) arrives, reset pulse makes switch S 1, S2, S3 short circuit, make the output of A2, A7, sampling hold circuit (4) become zero, so as to collect that next cycle occurs less than peaked peak value and of last one-period greater than the valley of minima of last one-period.This that is to say, reset start signal the collection period of next peak, valley.

Obtain the meansigma methods Um of arterial pressure if desired, then can add mean value operating circuit (3).The computing circuit of Us and Ud being delivered to A3, A4 and R2, R3, formations such as R4, R5 carries out computing.Wherein A4 is the unit inverting amplifier, i.e. K=-1, so that the negative value that obtains after the A3 computing is just got, it is output as meansigma methods Um, described Um=1/3(Us+2Ud).

Waveform shown in Fig. 4 is the waveform that sampling pulse forms the sampling pulse string (57) of circuit (6) output.We can be observed the wave form varies situation of Uaps, Us, Ud etc. in the collection period by Fig. 4.

Controller (26) comprises five parts: agitator OS, four phase clock generators of the long period short spacing that monostable trigger (60), (61), (62), XOR gate (64), (65), NAND gate (66) constitute; The A/D enabling gate signal circuit that monostable trigger (68) forms, the switch controlling signal that shift register (74) forms produces circuit; The reset signal generating circuit that NAND gate (72), monostable trigger (70) constitute.The method of attachment of each parts as shown in Figure 5.

The clock of controller (26) is from an agitator OS who is made of 555 timer chips, and its output cycle is the 3-4 square-wave signal of second (77) (referring to Fig. 6).Signal (77) triggers monostable (60).The time-delay of monostable (60) is adjusted at 100 milliseconds, and its output Q and Q trigger monostable (61) and (62) respectively.The time-delay of monostable (61) and (62) is adjusted at 50 milliseconds.The shift register (74) that the Q output signal (63) a tunnel of monostable (61) is fed and sealed in and go out is as input signal; Another Lu Yuqi Q output and through R13, the signal of C4 time-delay locates to carry out XOR at XOR gate (64), produces two burst pulses, and anti-phase through NAND gate (66) again obtains preceding two burst pulses in (67) waveform shown in Fig. 6.The Q of monostable (62) and Q output behind delay circuit R14, C5, are located XOR at XOR gate (65), also produce two burst pulses.Because the triggering signal of monostable (62) is the trailing edge of monostable (60) Q, so postponed 100 milliseconds, two burst pulses of XOR gate (65) output are latter two pulses in (67) waveforms of 100 milliseconds of delays like this.This part circuit comes down to four phase clock generators of a long period short spacing.With this four phase clocks signal deactivation A/D (34) work.

The burst pulse that the two-way XOR gate produces through synthesizing of NAND gate (66), obtains (67) waveform.This train of pulse is delivered to monostable (68) of 40 milliseconds of time-delays.Its Q output is as the enabling gate signal of A/D converter (34); Its Q output is as the clock (69) of shift register (74), referring to (69) among Fig. 6.

The shift register that four bit strings are gone into and gone out (74) is used for producing control signal A, B, C, the D of four path analoging switch.Its input is the Q output of monostable (61), and the width of signal (63) is 50 milliseconds.This pulse forms first clock pulses of signal (69) simultaneously through the delay of XOR gate (64), NAND gate (66) and monostable (68).Therefore, when this first clock pulses started shift register, the signal of input (63) was in high level, and this is inserted shift register.And second clock pulses be when arriving, and the high level of the signal of input (63) is over and done with certainly.Under three follow-up clock effects, four road signal A, B, C, the D of shift register are exported shown in the waveform of Fig. 6 like this.

The input of four path analoging switch inserts Us, Ud, Um and Uv respectively.The outfan of its four-way switch links together, and as total output, delivers to A/D converter (34) and does the time-division conversion.

Reset signal only acts on arterial pressure signal processor (20).As long as three amounts of Us, Ud and Um EOC can reset.Here use the D road output of shift register (74) and signal (69) with non-after, go to trigger monostable (70) with its resulting pulse, make 1 millisecond of wide burst pulse of its generation as reset signal (59), deliver to signal processor (20).

Above-mentioned data display equipment (22) can have multiple embodiments.Introduce another embodiment below.Its theory diagram is shown in Figure 8.

Data display equipment (22) comprising: sampling holder (90), (91), (92), digital voltage panel table (94), (95), (96), (97), controller (93), cardiotachometer (98).

The input of described sampling holder (90), (91), (92) connects Us outfan, Um outfan and the Ud outfan of signal processor (20) respectively, and its outfan connects voltmeter (94), (95), (96) respectively.Described controller (93) is made of agitator, frequency divider, monostable trigger, chronotron etc., and it exports reset signal (59), delivers to signal processor (20), (99) 100 milliseconds of the about late samples control impuls of this signal; It also produces controlling of sampling pulse (99), about 1 millisecond of its width, and the control end of sampling holder (90), (91), (92) is delivered in this pulse respectively.The control gate signal of controller (93) output connects cardiotachometer (98), and the gate cycle is 1 minute.Described cardiotachometer (98) is an enumerator that has the LED charactron to show.Its counting input end connects the outfan of heart rate detector (28).Voltmeter (97) is connected with the output Uv end of venous pressure test circuit (12).

Instrument for measuring blood pressure of the present invention compared with prior art has following good effect.

1, simple in structure, circuit is reliable, be easy to make.

2, certainty of measurement height.

3, can carry out large screen display.

4, with low cost.

5, be easy to safeguard.

Claims (6)

1, a kind of instrument for measuring blood pressure, contain prestage [14], in order to voltage signal Uaps, the venous pressure test circuit [12] of the arteriotony that has amplified to be provided, it is characterized in that the present invention also comprises: signal processor [20], heart rate detector [28] and data display equipment [22]; Signal processor [20] connects prestage [14], and data display equipment [22] connects signal processor [20], heart rate detector [28], venous pressure test circuit [12] respectively; Described signal processor [20] is made up of peak holding circuit [1], valley hold circuit [2], mean value operating circuit [3]; Described peak holding circuit [1] is in order to obtain the crest voltage Us that characterizes systolic pressure, it connects the controller in prestage [14], mean value operating circuit [3], the data display equipment [22] respectively, described valley hold circuit [2] is in order to obtain the valley point voltage Ud that characterizes diastolic pressure, it forms circuit [6], sampling hold circuit [4] etc. by valley value detection circuit [5], sampling pulse forms, and described valley hold circuit [2] connects the controller in prestage [14], mean value operating circuit [3], the data display equipment [22] respectively; Described mean value operating circuit [3] is in order to calculating mean arterial pressure Um, described Um=1/3 (Us+2Ud), and it connects data display equipment [22].

2, instrument for measuring blood pressure as claimed in claim 1, it is characterized in that described data display equipment (22) comprising: controller (26), multi-way switch circuit (24), A/D converter (34), intervalometer (38), data register (36), enumerator (39), data-out port (43), LED charactron display (44); Described controller (26) is used to produce reset signal, the variable connector signal of signal processing, the enabling signal of A/D, and it connects signal processor (20), multi-way switch circuit (24), A/D converter (34) respectively; Described multi-way switch circuit (24) simulates switch by one group four the tunnel and constitutes, and it connects signal processor (20), venous pressure test circuit (12), data register (36), A/D converter (34) respectively; Described A/D converter (34) also connects data register (36), intervalometer (38); Described enumerator (39) connects heart rate detector (28), intervalometer (38), data register (36) respectively; Described data-out port (43) and light-emitting diode display (44) connect data register (36) and intervalometer (38) respectively.

3, instrument for measuring blood pressure as claimed in claim 1 is characterized in that, described heart rate detector (28) is made of wave filter (80), attenuator (82), the circuit of averaging (78) and comparator A8.

4, instrument for measuring blood pressure as claimed in claim 1, it is characterized in that, described valley value detection circuit (5) is formed anti-phase and level compensation circuit by operational amplifier A 5, resistor R 6-R11 and potentiometer W, with so that the signal inversion of Uaps, and the DC level that superposes, described valley value detection circuit (5) also comprises the peak detection circuit that operational amplifier A 6, A7, diode D2, resistor R 12, capacitor C2, switch S 2 are formed, and is used to detect the time that valley occurs.

5, instrument for measuring blood pressure as claimed in claim 1 is characterized in that, described sampling pulse forms circuit (6) and adopts monostable trigger.

6, instrument for measuring blood pressure as claimed in claim 2, it is characterized in that, described controller (26) comprises agitator OS, four phase clock generators of the long period short spacing that monostable trigger (60), (61), (62), XOR gate (64), (65), NAND gate (66) constitute, the A/D enabling gate signal circuit that monostable trigger (68) forms, the switch controlling signal that shift register (74) forms produces circuit, the reset signal generating circuit that NAND gate (72), monostable trigger (70) constitute.

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