SIMPLE AUTO ELECTRONIC TOURNIQUET

Abstract

A simple auto electronic tourniquet includes a cuff, a pressurizing means for gradually raising the internal pressure of the cuff, a depressurizing means for gradually decreasing the internal pressure of the cuff, a pressure detecting means for detecting the internal pressure of the cuff, a target pressure setting means for setting the internal pressure of the cuff to a target pressure, a pressure control means for controlling the internal pressure of the cuff so that it gets close to the approximate value of the target pressure, and a notifying means for notifying that venipuncture is performable. In order to avoid excessive pressures, long-time performance of avascularization, sudden rise of pressure, which may cause patients to feel stressed, the width of the cuff of the tourniquet of the present invention shall be 75 mm or less, and more preferably in the range between 10 mm and 60 mm.

Claims

1. A simple auto electronic tourniquet comprises: a cuff, a pressurizing means for gradually raising the internal pressure of a cuff, a depressurizing means to gradually decreasing the internal pressure of the cuff, a pressure detecting means for detecting the internal pressure of the cuff, a target pressure setting means for setting the internal pressure of the cuff to a target pressure, and a pressure control means for controlling the internal pressure of the cuff so that it gets close to the approximate value of the target pressure, and a notifying means for notifying that venipuncture is performable.

2. The auto electron tourniquet as claimed in claim 1, wherein the depressurizing means is able to depressurize the internal pressure of the cuff by operating an operating device provided off the cuff.

3. The simple auto electron tourniquet as claimed in claim 1, wherein the width of the cuff is 75 mm or less.

4. The simple auto electron tourniquet as claimed in claim 1, wherein the capacity of the cuff is 80 cc or less.

5. The simple auto electron tourniquet as claimed in claim 1, wherein the target pressure setting means is able to select an arbitrary fixed value by operating from the outside.

6. The simple auto electron tourniquet as claimed in claim 1, wherein a biological signal detection means is further provided, and the target pressure setting means sets the target pressure based on the result of detection of biological signals by operation of the biological signal detection means.

7. The simple auto electron tourniquet as claimed in claim 1, wherein a biological signal detection means is further provided; the target pressure setting means is able to select an arbitrary fixed value by operating from the outside; the biological signal detection means detect a biological signal in a condition pressurized with a value of the internal pressure of the cuff corresponding to the arbitrary fixed value; and the notifying means notify that venipuncture is performable when the biological signal detection means detects the biological signal.

8. The simple auto electron tourniquet as claimed in claim 1, wherein a biological signal detection means is further provided; the target pressure setting means is able to select an arbitrary fixed value by operating from the outside; the biological signal detection means detect a biological signal in a condition pressurized with a value of the internal pressure of the cuff corresponding to the arbitrary fixed value; and when the biological signal is not detected, the target pressure setting means resets the internal pressure of the cuff to a target pressure which is higher than the previously selected arbitrary fixed value.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0036] FIG. 1 a view showing an auto electronic tourniquet of the present invention in the mounting condition

[0037] FIG. 2 a functional block diagram of an auto electronic tourniquet of the present invention

[0038] FIG. 3 an external view of an auto electronic tourniquet of the present invention

[0039] FIG. 4 an external view of the cabinet of an auto electronic tourniquet of the present invention

[0040] FIG. 5 a first flow chart showing a series of operations from the start of pressurization, notification of availability of venipuncture, to the gradual depressurization

[0041] FIG. 6 a second flow chart showing a series of operations from the start of pressurization, notification of availability of venipuncture, to the gradual depressurization

[0042] FIG. 7 a third flow chart showing a series of operations from the start of pressurization, notification of availability of venipuncture, to the gradual depressurization

[0043] FIG. 8 a conception diagram showing a relationship between width of the cuff and the necessary internal pressure of the cuff in a tourniquet

MODE FOR CARRYING OUT THE INVENTION

Example 1

[0044] An auto electronic tourniquet shown as the first embodiment of the present invention, as described in FIGS. 1-4, has a manchette (cuff) 1 mountable around an upper arm U which is one of the limbs of the human body and a cabinet 20 integrally provided with the cuff 1. The cabinet 20 has a controller 2 inside.

[0045] The cuff 1 is configured to be maintained in a pipe-like shape by a hook-and-loop fastener 1a when mounted around the upper arm U and to be easily detachable to and/or from the upper arm U. Also, the cuff 1 is provided with a pressure bag 1b at a portion thereof which is to be the inner surface when formed in a pipe-like shape. The pressure bag 1b provides pressurizing force to the upper arm U. The pressure bag 1b is provided with a pump 51 for supplying air pressure to the pressure bag 1b and a valve 52 for adjusting pressure in the pressure bag 1b. The pressure bag 1b is further provided with a pressure sensor 53 for detecting the inner pressure of the cuff and a biological signal extraction unit 54 for extracting and detecting only a portion of the pressure detected by the pressure sensor 53 which corresponds to a pulse pressure.

[0046] The cabinet 20 is provided with the controller 2 having hardware resources of a computer. The controller executes software with sequence program, thereby various controls described hereinafter are performed.

[0047] A power circuit (not shown in the drawings) is started by pushing down a power switch 21. A mode change-over switch 22 is for the purpose of switching binary mode, i.e., auto mode and manual mode. The manual mode is further set to 100 mmHg, 150 mmHg, and 200 mmHg as the fixed values for the target internal pressure of the cuff. Whenever the mode change-over switch is pushed down, change of the mode is possible. A pump 51 is started by pushing down a start switch 23, and air discharged from the pump 51 is filled into the cuff. When an operation of pressure release is needed in the cabinet 20, the valve 52 is thrown open by pushing down a release switch 24 and the internal pressure of the cuff decreases.

[0048] A switch for elbows 25 is connected to the cabinet 20 through a lead wire 25a and has a common function with the start switch 23 and the release switch 24. Namely, by pushing down the switch for elbows 25 once, pressurization of the cuff is started. Also, by pushing down the switch for elbows 25 again after the completion of venipuncture, the valve 52 is opened and the cuff is depressurized. When venipuncture is performed, as injectors, syringes and/or gauzes will usually occupy both hands of nurses and/or medical doctors, and an operating means for the internal pressurization/depressurization of the cuff which is operatable other than by hands has been desired. By using the switch for elbows 25, the internal pressure of the cuff may be released safely and surely while venipuncture is performed. The cuff 1 and the cabinet 20A constitute a cuff section, and the switch for elbows 25 corresponds to an operating device provided on other than the cuff section.

[0049] A pulse pressure indicator 31 is an LED lamp and flashes on and off in response to the presence or absence of biological signals (pulse pressures) extracted by the biological signal extraction unit 54 from the pressures detected by the pressure sensor 53. Thereby, whether avascularization is appropriately performed is visible. Further, the pulse pressure indicator 31 may be configured to be lighted at the time when avascularization is finished, namely when venipuncture becomes possible. In this case, the pulse pressure indicator 31 functions as a notifying means. Alternatively, when unusual situation occurs such as excessive pressurization, insufficient pressure, or a lack of battery, the pulse pressure indicator 31 may be functionalized as a means to notify the unusual situation by high-speed flashing. However, those additional notifying functions are not necessarily used jointly with the pulse pressure indicator 31 and may be performed by using a cuff pressure indicator 32 or a mode indicator 33 (both of which are described hereinafter) or by jointly using both or either of them.

[0050] The cuff pressure indicator 32 consists of a plurality of LED lamps and the LED lamps are lighted in order in response to the internal pressure of the cuff detected by the pressure sensor 53. Also, the mode indicator 33 consists of a plurality of LED lamps, and one of the LED lamps corresponding to the current mode [either automatic (automatic operation), 100 mmHg (manual operation), 150 mmHg (manual operation), or 200 mmHg (manual operation)] is lighted and notifies the current mode in response to the operation of the mode change-over switch 22.

[0051] When avascularization is finished and venipuncture is possible, a buzzer 40 rumbles and notifies the user the situation.

[0052] Hereinafter, operation of an auto electronic tourniquet with using a fixed value of avascularization pressure selected by manual operation will be explained with reference to FIG. 5.

[0053] A target internal pressure of the cuff is selected from the plurality of fixed values set in the manual mode by pushing down the mode change-over switch 22 (step S501). The mode change-over switch 22 functions as a target pressure setting means. Then, when the start switch 23 is pushed down (step S503: Yes), the pump 51 is driven and the valve 52 is completely closed and the internal pressure of the cuff starts increasing (step S505). While increasing, the internal pressure of the cuff is detected by the pressure sensor 53, and when it reaches a setting pressure (step S507: Yes), the completion of avascularization is notified (step S509). The notifying means may be to light either of the above-described indicators or may be to rumble the buzzer 40. Also, the operation of the pump 51 stops and the valve 52 remained closed to maintain the internal pressure of the cuff (step S511). Not shown in the Figures, although the internal pressure of the cuff is maintained in a pressure approximate to the target internal pressure of the cuff by closing the valve 52, it may be configured such that the pressure sensor 53 continues to detect the internal pressure of the cuff in preparation for slight leak of air, and when the difference between the internal pressure of the cuff and the target internal pressure reaches a predetermined value, the pump 51 is driven again. The pump 51 and valve 52 collaborate with the controller 2 and functions as a pressurizing means and a pressure control means.

[0054] After venipuncture is performed in this state, the release of the internal pressure of the cuff is usually needed in a state that the upper arm U is still punctured. Nurses and/or medical doctors who perform venipuncture release the pressure by pushing down either the release switch 24 or the switch for elbows 25. When either the release switch 24 or the switch for elbows 25 is pushed down (step S513: Yes), the valve is opened and the internal pressure of the cuff drops (step S515). The release switch 24, switch for elbows 25, and valve 52 collaborate with the controller 2 and function as a depressurizing means.

Example 2

[0055] Then, an operation of the auto electronic tourniquet with automatically setting a target avascularization pressure based on biological signals will be explained with reference to FIG. 6.

[0056] The automatic setting mode is selected by pushing down the mode change-over switch 22 (step S601). Then, when the start switch 23 is pushed down (step S603: Yes), the pump 51 is driven and the valve 52 is completely closed, and the internal pressure of the cuff starts increasing (step S605).

[0057] The pressure sensor 53 detects the internal pressure of the cuff during its increase, and the biological signal extraction unit 54 extracts and detects only a portion of the pressure values detected by the pressure sensor 53 which corresponds to a pulse wave. Deflection of the detected pulse wave is recorded over time, and when the maximum pulse wave is detected as a result of continuous detection (step S607: Yes), and with a time interval (buffer) corresponding to two beats of pulsation being imposed (step S609), the completion of avascularization is notified (step S611). The time interval (buffer) is not limited to using beat rate and may be configured to delay the operation by a predetermined second (i.e. one second). In this embodiment, the pressure sensor 53 and the biological signal extraction unit 54 collaborate with the controller 2 and functions as a target pressure setting means. The notifying means may be to light either of the above-described indicators or may be to rumble the buzzer 40. Also, the operation of the pump 51 stops and the valve 52 remained closed to maintain the internal pressure of the cuff (step S613). As in the first embodiment, in order to maintain the internal pressure of the cuff, a configuration is adopted such that the internal pressure of the cuff is continuously monitored by the pressure sensor 53, and when it decreases by a predetermined range or more, the pump 51 is driven to additionally pressurize it.

[0058] After venipuncture is performed in this state, the release of the internal pressure of the cuff is usually needed in a state that the upper arm U is still punctured. Nurses and/or medical doctors who perform venipuncture release the pressure by pushing down either the release switch 24 or the switch for elbows 25. When either the release switch 24 or the switch for elbows 25 is pushed down (step S615: Yes), the valve is opened and the internal pressure of the cuff drops (step S617).

Example 3

[0059] Then, hereinafter, another operation of an auto electronic tourniquet of the present invention will be explained with reference to FIG. 7, in which while a fixed value of avascularization pressure is selected by manual operation, whether avascularization is performed in an appropriate condition is detected by considering biological signals.

[0060] A target internal pressure of the cuff is selected from the plurality of fixed values set in the manual mode by pushing down the mode change-over switch 22 (step S701). Then, when the start switch 23 is pushed down (step S703: Yes), the pump 51 is driven and the valve 52 is completely closed and the internal pressure of the cuff starts increasing (step S705). While increasing, the internal pressure of the cuff is detected by the pressure sensor 53. When it reaches the setting pressure in the manual mode (step S707: Yes) and a predetermined biological signal is detected by the pressure sensor 53 and the biological signal extract unit 54 (step S709: Yes), the completion of avascularization is notified (step S711). The notifying means may be to light either of the above-described indicators or may be to rumble the buzzer 40. If a pulse wave with strength in a predetermined level or more is detected at the time when the internal pressure of the cuff reaches the setting pressure in the manual mode, a predetermined biological signals may be assumed to be detected. Alternatively, it may be configured such that pulse waves are detected over time by the biological signal extraction unit 54, and if a maximum pulse wave is detected during the detection, a predetermined biological signals may be assumed to be detected. Further, it may be configured such that pulse waves are detected over time by the biological signal extraction unit 54, and if a maximum pulse wave is detected during the detection and if a pulse wave at the time when the internal pressure of the cuff reaches the setting pressure in the manual mode falls within a predetermined range of maximum pulse wave, a predetermined biological signal may be assumed to be detected.

[0061] When a predetermined biological signal is not detected by the pressure sensor 53 and the biological signal extract unit 54 (step S709: No), resetting the value of the target internal pressure of the cuff is conducted (step S715). A resetting value of the target internal pressure of the cuff shall be a value which adds 50 mmHg to the original setting pressure in the manual mode. However, if the value of the setting pressure in this stage has been set to 200 mmHg (step S713: Yes), the increase of pressure is not to be conducted, and an error is notified (step S717). When a predetermined biological signal is detected, the operation of the pump 51 stops and the valve 52 remained closed to maintain the internal pressure of the cuff (step S719).

[0062] After venipuncture is performed in this state, the release of the internal pressure of the cuff is usually needed in a state that the upper arm U is still punctured. Nurses and/or medical doctors who perform venipuncture release the pressure by pushing down either the release switch 24 or the switch for elbows 25. When either the release switch 24 or the switch for elbows 25 is pushed down (step S721: Yes), the valve is opened and the internal pressure of the cuff drops (step S723).

[0063] In the auto electronic tourniquet of the present invention, its characteristic feature is that the width of the cuff is configured to be 75 mm or less. The technical significance of this point will be mentioned below.

[0064] The width W of the cuff of a tourniquet is preferably smaller from the viewpoint of easy mounting and short pressurizing time (FIG. 8 (a)). This point may be an advantage for the auto electronic tourniquet of the present invention which is not placed under the restrictions under which the common sphygmomanometers are placed (refer to FIG. 8 (b)). Namely, when a cuff with smaller width is used in conducting sphygmomanometry, measured values of blood pressure have to be higher. This is conceived that if pressurized area is smaller, higher pressure is required for providing a stenosis to blood vessel (a physical transformation of blood vessel) to the same extent as pressurized area being not smaller. In this regard, the object of the auto electronic tourniquet of the present invention is to provide a stenosis to blood vessel in relation to the internal pressure of blood vessel, and not to measure mean blood pressure. Further, changes of pulsation amplitude of internal pressure of the cuff is produced by a vascular stenosis of the pressurized portion of blood vessel, and when pulsation amplitude becomes maximum, an external force similar to the mean value of the internal pressure of blood vessel is applied. Namely, if a pressurized state of detecting a maximum value of pulse wave is realized, an optimum state for avascularization will be realized. In order not to make patients feel excessively stressed by the optimum avascularization state, while having studies the time until the internal pressure of the cuff reaches its maximum value and/or its target value, we have found that the width of the cuff equal to or less than 75 mm may produce a desired avascularization state in a short time without making patients feel unnecessary stress. Still, when the width W of the cuff is too small, as a strong tightening force is applied to a small area of the limb of a patient, the patient feeling more stressed. In addition, as a high internal pressure of the cuff is required, durability of the pressurized bag may be spoiled. Thus, the width of the cuff is preferably 10 mm or more, and it is also preferably 60 mm or less for prompt realization of an optimum avascularization state.

DESCRIPTION OF THE REFERENCE NUMERALS

[0065] 1 manchette (cuff) [0066] 2 controller [0067] 20 cabinet [0068] 21 power switch [0069] 22 mode change-over switch [0070] 23 start switches [0071] 24 release switch [0072] 25 switch for elbows [0073] 25a lead [0074] 31 pulse pressure-indicator [0075] 32 cuff pressure indicator [0076] 33 mode indicator [0077] 40 buzzer [0078] 51 pump [0079] 52 valve [0080] 53 pressure sensor [0081] 54 biological signal extract unit