CA2096836A1 - Medico-technical process and means for measuring blood irrigation of organs - Google Patents
Medico-technical process and means for measuring blood irrigation of organsInfo
- Publication number
- CA2096836A1 CA2096836A1 CA002096836A CA2096836A CA2096836A1 CA 2096836 A1 CA2096836 A1 CA 2096836A1 CA 002096836 A CA002096836 A CA 002096836A CA 2096836 A CA2096836 A CA 2096836A CA 2096836 A1 CA2096836 A1 CA 2096836A1
- Authority
- CA
- Canada
- Prior art keywords
- measuring
- sensor
- code
- instrument
- connecting element
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/14542—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue for measuring blood gases
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/1468—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means
- A61B5/1473—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means invasive, e.g. introduced into the body by a catheter
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/1495—Calibrating or testing of in-vivo probes
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
- A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
- A61B5/6847—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
- A61B5/6848—Needles
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/02—Details of sensors specially adapted for in-vivo measurements
- A61B2562/0209—Special features of electrodes classified in A61B5/24, A61B5/25, A61B5/283, A61B5/291, A61B5/296, A61B5/053
- A61B2562/0215—Silver or silver chloride containing
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/04—Arrangements of multiple sensors of the same type
- A61B2562/043—Arrangements of multiple sensors of the same type in a linear array
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
- A61B2562/08—Sensors provided with means for identification, e.g. barcodes or memory chips
Abstract
A measurement device relates to a patient (500) connected by a coded mask (501) to a hydrogen container (502). A perfusion container (503) is connected by corresponding connecting elements to a perfusion needle (504). Measurement probes (506), as well as a surgical instrument (507), are also connected to the measurement device (507) by connecting elements provided with corresponding fittings. Implanted probes (505) are provided with an electromagnetically readable code. Similarly, all used utensils and instruments are provided with a code (510).
Description
~ ~J V j ~J ~J j IC~L T~C~`TOLOG~ P~O GSS ~OR ME~SURI~G THE BLOOD F~OW IN ~1 ORG~N, ~D ME~NS TH~REFOR
The present invention relates to a process for measuringthe blood flow in an organ, partic:ularly in human tissue, employing the hydrogen clearance methcd, and suitable means for performing this process.
Such processes and measuring inst.-uments for it are known in the medical field and serve the pur~os2 of bo~h diagnos~ics and monitoring of the course and success of therapy or of a surgical operation. In this proc~ss, the blood of the su~ject is enriched with hydrogen and used as an electrolyte, which with two electrodes introduced into the tissue to be studied forms a galvanic element. The electrical voltage of this ele~ent is determinedby the concentration of the hydrogen in the blood, among other factors. When this process is employed, the hydrogen is introduced into the blood with the air of respiration or by lnjec~ion. .~s soon as the voltage between the electr~des has attained a ce~ain ii~it value, the delive-y of hyd_ogen is . , .
discontinued and the decrease in voltage as a function of time is ~
observed. The steepness of the ~easured curve of this function is ~-a measure for the tissue blood ~low, in which the hydrogen-enriched blood is re~oved and -sDlaced by hydrogen-f~ee blood.
The theoretical bases of t.iis process, and in particular the calculation or the potentials or the electrodes as a function of the hydrogen ion concentration w~th the aid o~ Nernst's equat on and the determination of the blood flow of a tissue volume from the decrease in concentration of the hydrogen in the blood with `~
the aid of diffusion principles, are described in detail, for instance by ~. Auc.~land e~ ai, in C -culation Research, Vol. ', ~;~
1964, pp. 16~ ff.
Although determining the blood flow of tissue with the aid of inert gases such as hydrogen has been known .or at least 40 ; ; !
years and has been discussed in many ublicaticns, the practical applic~tion of 'his pr~c~ss was prev~ously lim~ed ~o animal experimentation, or to measuring the blood flow rate at the tip of the little finger or a human being. The reasons for this are simple. With the e~uipment previously used to per.orm the process desc~ibed, evaluatable and reproducible measurements could be carried out only if the current intensity bet~een the electrodes and hence in the blood as well, that is, in the tlssue to be stud ed, was at least 1 x 10-6 A, a.value which s vhysiologically objectionable or even impermissible for some ~issues.
One such measuring instrument is described, for instance, in the article entitled "H2 Clearance ~easuremen~ of Blood Flow:
Review of Techni¢ue and Polarographic Principles"; ~ise Young, in STROK~, Vol. 11, No. 5, September-October 1980, pp. 552-564.
~ n appar2tus ~lth which, for the first ti~.e, the determination of tissue blood flow by the advantageous hydrogen clearance method can be used without the measuring current that is physiologically objectionable for human beings is described in ~urovean ~atsnt .~pplicatlon 0 ~52 276, f~r e~amvle.
~ lthough t;~e process desc~i~ed in ~his rarerence is a suitable method for measuring the blood flow in human tissue, it has been found in practice that in long-ter~ measurements, the highly sensitive electrodes required for this process relatively quic.~ly eithe- ~ecvme coatad ~lth endosenous anc especially fibrin-containing substances, or oxidize, thereby impairing the blood flow measurements made over a long period of time.
Another problem arises in the measurement of the spatial distributlon of t~e blood flow in the tissue to be studied, which is especiall~ desirable for long-tarm measurements. In such a measurement, multiple sensors are introduced into the tissue at multiple spa~ially separated points. I- usabia results are ~3 De attained, several measuring instruments, at undesirably high ,. ' . . ~ . .
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expense, are cur_entlv needed to evaluate the measured values scanned ~y the var~ous sensors. Partlcularly in long-ter~
measurements, this spatial measurement is made more difficult by the repeated insertion of new sensors and the calibration of these newly inserted sensors. It is self-evident that inserting new sensors at predetermined points in an organ to be studied involves undesirably high ex?ense for equipment and can be done only by suitably t_ained phvsicians. Particularly, it has also been found that given the great number of measuring electrodes available, technically untrained persons often us~ the wrong electrodes and/or inappropriate elect-odes for the particular equipment, which makes the measurements wrong. ~-In professional circles, the need therefore exists tocreate a process and means for performing this process that do not have these disadvantages and with which process long-term - -measurements in particular can be carried out with high measuring accuracy, in a simple and reliable way, even with spatial measurements. Looking for mistakes during surgery, under sterile external conditions, is flatlv unacce~table.
The object or tne presen~ invention is therefore to c-eate a process for measuring the blood flow by the hydrogen clearance method that overcomes the known disadvantages and in particular makes possible reproduci~le long-term measurements with multiple sensors and hl~hly sare mani~ulation. ~-In particular, the object of the present operating process is to make it possible to monitor whether the various sensors are operative and whether the connection between the measuring instrument and the sensors is proper, and to o~erate these sensors simultaneously wlth a single measuring ins~rument. -This object is attained by the present invention, which envisages a process or the type àiscussed at the outset that has the characteristics recited in the body of claim 1.
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In par~icular, the process ac~ording to ~he inventlon envisages ~he US2 of ' nterc.~angeable sensors of whate~er t~pe, or connecting elements or other medical technology utensils, which are inseparably provided with codes, to enable monitoring their origin, age and type, for lnstance, so that in the assemDled state, in other words, when ready for use, their proper connection can be monitored, or so that they can be operated by a single measuring instrument and/or therapeutic equipment, or in addition to enable ante-ograde and/or retrograde functional control and monitoring.
The advant~ges attained by the invention are substantially the increase in functional reliability and hence~atient safety, particularly from tne monitoring of all the contac~s and functions bet~een the measuring instrument and the arbitrarily disposed sensors, medical technology instruments or utensils; the capability of per~orming long-term measurements with increased accuracy and multidimenslonal aisplay of the measurement values;
quality assurance; and versatility in use made possible by the modular ccns~ruclion.
In addition, the sensors and/or connecting eiements may feed back or transmit stored or measured information. This mode of operation also enables purposeful control of special functions of the sensors.
~ ~easuring inst-ument, or in this cas2 a monitor as ~ell, which is suitable for performing the process of the invention has at least the characteristics recited in present claim 4.
Essentially, the measuring electrode and the reference elec~rode comprise metals whose chemical intrinsic potentlals are close to one another. In order to form the difference between their potentials, both the measuring electrode and the reference electrode are connec~ed via suitable suppl~ leads to the inputs ~f an operational amplifier. The measuring electrode, the reîerenc~
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elec~~ode and ~he neutral elec_-ode, with their supply leads, have shielding agains~ eJ~ternal dis~u_~ance fields. ~o lnduce an opposite potential in the tissue c~mpared with inductively or capacltively coupled potential fluctuations, the shields of the measuring and reference elect~odes and their supply leads are connected on the one hand to the neutr 1 electrode via the positive input of a voltage amplirier circuit, and on the other hand, the negative input of this voltage amplifier circuit is connec'ed to a voltage divider for forming the mean value of the potential of the measuring and reference electrodes that is connected bet-~een t~e suppl~ leads of these electrodes.
For using a plurality of sensors, particul~arly for measuring the spatial dis~ribution of blood flow in an organ, the measuring instrument is preferably equipped with an electronic multiplexer, -~ith which the voltage applied to the various sensors is scanned in succession, for example five times per second. `~
Since the measuring ~art of the instrument is galvanically -separate from the other parts of the instrument, this apparatus maXes it possiole to per~^or~ the hydrogen clearance method for determining ~iood flow using pAysiologically unoojec=ionable ~-~
current intensities and in a reproducible manner. ~ -~ n important factor for safely performing the process is components that carry a code detectable by the aforementioned measuring instrument. These codes may be provided with the aid of electronic, electromagnetic or optical structural elements. It will be understood that to enhance patient safety, these encoded components may be affixed to all the medical technology utensils needed or desired for the study. In any case, however, the sensors necessarv r^or the process of the lnvention and their connecting elements must be inseparably provided with such codes.
~ur-her prererred characteristics of the proces~ according to the invention and of the means for performing this process are recited . ' ; ' ' , ' . , :; ' ; :
. .. . .
in the claims.
The inventicn is desc~ bed in furt~e~ detail below in ter~s of an exemplar~ embodiment.
Shown are:
Fig. 1, a flow chart with the method steps essential to the invention;
Fig. 2, a block circuit diagram of a measuring instrument suitable for performing the process;
Fig. 3, a circuit diagram of the analoq or measuring part of a measuring instrument suitable for.performing the process;
Fig. ~, a more-detailed circuit diagram of the analog or measuring part of a measuring instrument suitable-for performing the process;
Figs. 5a-5q: connection pieces, connecting elements, ox closure elements, of the kind that ar3 suitable for performing the process of the invention;
Figs. 6a-60: sensors of the kind that are suitable for performing the process of the invention;
Fig. 7: one ~ossible ~easuring setup for perfor~inq the process according to the invention.
In Fig. 1, the various steps in the present process are assembled into a flow chart. To measure the spatial distribution of blood flow in a human organ, accord:ing to the invention, in a step a), a plurali_y of detachable, indiv~dually encoded sensors are implanted, in spatially distributed fashion, in a tissue to be studied. As a rule, this step is ca~rie~ out by an experienced .
pAysician. In a second step b), the various sensors, now implanted, are connected via encoded connecting elements to a measuring instrument for deter~ining the blood flow rate by the hydrogen clearance method. Thanks to the present invention, this second step can be carried out even by semis~ lled assistants. In a third step c3, the various code values of the sensors, , ~. . , , . :
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h v ~J ù ~ v connecting 2 lements, and generally o~her medical utensils are read and chec~ed D~r =he ~easu~ing ins~rumen~ a corrQc connection has not been made, then a fault report F is accordingly displayed by the measu~ing instrument. If the monitoring car~ied out by the measuring inst-ument does not lead to a fault report, the measured value detection unit is enabled to detect signals at the measurin~
electrodes. Simultaneously with the measurement d), the measured values, along with the associated code values, are stsred in ~emory, dis?layed, or delivered for evaluation .~.
Particularly once a first measurement has been made, the sensors can be left in the tissue and method step c) can be repeated at regular intervals. After a desired period of time, a further measurement can be made, preferably by the hydrogen clearance method. The measured values of the various measurements are then subjec'ed to evaluation ~. The block ci-cult diagram shown in Fig. 2 shows a power pack 100 that is connected to a power source 200 that has a potQntial lock of at least 4 ~'~ and supplies an analog part 300 with the necessary voltage. The sensors ~ and ~ are connected to the analog part 300. The likewise galvanically separate output of the analog part 300 is connected to a digital part ~00.
For long-term measurements, catheter~ e sensors are implanted, t~rough ~hose cannulas the electrodes necessary for the desired measurement are introduced, preferabiy wi.h a needle.
Depending on the type of electrodes, thev may be removed again and/or replaced after a measurement series has been performed, or unsoiled electrodes can be used for measurement repeate~ly by successively puiling out the needle.
This~flow chart may also be used for other measurement and therapy techniques, such as O~, pH, glucose, potassium, temperature, blood pressure and intrac.anial pressure measurements, as well as for medication-infusion equipment.
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Fig. , s~ows the measuring ~ar~ of a measuring instrument sui~able .or per 3r~1ng the pr~cess~ The measure~ Jalue detection unit 46 is essential to the invention and is connected to a sensor plug 52. TAe ~lxed resistor 54 together with the grounded coding resistor 49 forms a voltage divider whose value is recognized by the measured value detection unit 46. In this embodiment, the measuring elect.ode 11, shielded at 25 from external dis.urbance potentials, is connec_ed via a supply lead 12 to a first impedance converter '~, whose output is conne~ted to t~e negati-~e input of a measuring amplifier 13. A reference electrode 15~ shielded at 27, is connected via a supply lead 17 to a second i~pedance converter 16, whose output is connected to the positive input of the measuring amplifier 13 via a resistor that is variable for zero balancing. The measuring instrument used preferentially for the process of the invention also has a driving neut_al elect~ode 29, with which opposed fields are actively coupled into the measuring reason in order to compensate .or external disturbing fields. To that end, the mean value of all the signals from the voltage divider 31 is kept at 0 V Dy varying the common grour.d. The ground feedback via the two inverting amplifiers 28 or via a PI
controller is done with high impedance, for instance with an impedance of lO0 kn. The supply lead 24 for the disturbance voltages is ln communication with the shields 25, 27. The output of the differential amplifier 13 is connected to an analog/digital converter 46 via a low-pass filter. The component 46 shown in Fig. 3 detects six signals and has a 10-byte resolution (1024 component). Triggerlng on the digital side is done by a microprocessor 41 via a data bus ~l having at least four leads ~hat are connected Vi2 optical couplers 7 to the A/D converter 46. For the supply, a suitable repeating coil 48 is provided.
It will be understood that even h-gher-resolution components, such as a 4096 (12 byte) component may be used. The . , : . .. ,, : .
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free analog inputs 33, ~O c~n then derec~ fur her signals, such as pH ~a ue, te-nper2tlrQ, or codes. 'iia ~he four dlgital leads ~1, signals can be t-ans,erred to the analog part simply, using the same connections. The transfer is done serially and may be expanded at will. ror instance, the capability exists of controlling the cur,ent for H2 production, per-orming a switchover of measurement range, or of varying OFFSET and amplificatlon is signal detection. The digital par, primarily comprlses the processor 41, whose program `is stored in an EP~OM of the memory 42. A timer and an 8- to 32-kilobyte RAM memory is also provided, whose operation is backed up with a built-in battery. In the R~, a plurality of measurements can be stored and cal-led up again later. The inter~ace components for the display 43; serial interface 45, keyboard 44 and converters are well-known to one skilled in the ar'. For the display, LC~s or complete monitors can be used equally well. Acoustical warning signals may be built in without any inventive erfort.
In a proven embodiment, the voltage of the sensors is measured ~ ~ mes pe~ second. ~he current value is calcula_2d f~om that and shown in the display. In addition, the signal or the sensor is read and stored in the nonvo:Latile memory and made available for evaluation. Preferably, for further illumination of disturbances in the measured values, the mean value of the exponential regression is calculat-d rrom ~ to 10 measured values.
This a~paratus is eaually suitable for flow measurement in veterinary medicine, in laboratory work, and for industrial applications.
Fig. 4 shows the circuit diagram of the analog or measuring part ~or t-~o coded sensors, in detail. The sensors are connected to the instrument by a multipole plastic plu~ connection and a highly flexlble, sAielded sensor cable. Each of these parts has a special code, which can be recognized by the instrument.
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~ u ~ ~, ) u ~a Figs. a-~q show varlous embodiments for connection pieces and connec~ing ele~e.~s or clos~re e ements of the ~ind needed to perform the process of the invention. Connection pieces and connecting ele~ents of this kind and other are well-known in medical technology and according to the invention are provided with an electronically detectable code, or in other words if - necessary include at least one shielded elect~ic~l lead ~ith a suita~le contac_ point for producing an electrical connection bet~een a code reader unit, which is independent cr lntegrated into the m~asuring instrument, and the code-carrying element, which is embodied for instance of a resistor element, a microchip, or other elec~_onic components having a definable-value or state.
Figs. 6a-60 show examples of sensors and in par~icular electrode carriers, of the kind that are possible for performing the process of .he invention. Since in practical ter~s the area of potential use in medicine is unlimited, the-sensors also have a great many forms and properties. The following list is therefore limited merely to several basic types, which in their embodiment can naturally ce r~adily adapted ~3 e.Yi sting needs. In the variant shown in Figs. 6f, 6g, 6k and 61, each electrode or each measuring and/or therapy head is guided individually. ~s a result of this embodi~ent, it is possible to place the various electrodes locally independently. The result is accordingly three individual electrode carriers with the associated electrode materials.
In the variant of Fig. 6m, the electrodes are combined in one sensor. ~s a result of this embodlment, all the electrodes are placed ~t the same location. The result is accordingly only a single sensor, with the associated elec__ode materials. This specialized emDodiment even makes i- possible to expose only the sensitive measu-ing electrodes for the desired measurement, and then to retrac_ them back into the protective sheath again.
In the variant of Figs. 6a and 6n, a plurality of :: " . : : . . . : ::
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elec'~odes are c~ined in one sensor. Thls embodi~ent makes three-dlme~siona me~surement possibla. Accor~in~ly, ~here is only a sin~le sensor with the associated electrode materials.
In the variant of Fig. 6i, a plurality of elect-odes of the same electrode ma~2rial are accommodated in one senscr. This embodiment maXes three-dimensional area measurement possible. The result is accordingly one area sensor with a plurality of measuring elect~odes, and one neutral and one driving electrode each, along ,iit~. the associa`ted e~ec.rode mate~ials.
It will be understood that all possible forms may be used as the electrodes, for instance of the kind al~eady Xnown as membrane-covered elect-odes, implantable electrodes for H2, 2 or bioelectrical slgnals, stick-on electrodes, surface electrodes, one-way electrodes, needle electrodes, brush electrodes, disk mic.oelectrod2s, thin-film electrodes, and 3-D elect~odes. These electrodes can equally well be integrated into ultrasound sensors or catheters, such as venous catheters, central venous catheters, arterial catheters, cardiac catheters, balloon catheters, shunt meas~_ing ca_:~ete's, s'anosis meas~r ng c~thet~rs, liver catheters, Port-a-cath catheters, intrac~anial pressure catheters, drainage catheters, kidney~urine catheters, sensor catheters (for temperature, blood pressure, H2, 2~ etc), or in biopsy and aspiration instruments, of ~he kind also shown in Figs. 50-5q and 6a-6e. Examples of elect-ode mat~rials ~hat have proved particularly suitable for the measurin~ tip are the following:
platinum, silver~silver chloride, silver, platinum-iridium, iridium, platinum-iridium-based, film electrodes, platinum-~lack-covered, microelectrodes, multibarreled electrodes, mic-opipette electrodes, tlngsten, tungs'en glass fibers, platinum-rhodium-quartz fibers, tantalum-on-sapphire multielectrodes, platinum-tantalum polyimides, and metal-noble met~is. The suDstrate materials preferably used are polyamide, p+-type silicone, n-type .: .: ~ .
.
' '' ' ' ' `'" ~,'' ' ' ' ' ';. ~ " ~ ` ' .' '' , ' " ' ' ' ` ' ' silicone, silicone rubbers, Kapton (polyimide), ?yrex, Teflon, Tri-.~ll insuia~- sil~er ~ire, Dac~on-.~esh matri~, car~on, polyethylene, polyethylene glycol, polyurethane, borosilicates, epoxy resin, Hysol epoxy, Epoxylite, cyanoacrylate, stainless steel, Silast c, Parylene-N, polystyrene, polyepichlorohydrin, cellulose acetate membrane, and PVC membrane.
The sensors or therapy heads may also have t- nsistors or other sensors as well as controllable valves.
~ li the sensors used in connection with the _lcod flow measuring instrument have integrated sensor detection. This encoding has the advantage that the instrument automacically recognizes the ap~licable sensor type, so that sensor-specific and measurement-type-speciflc soft~are can be loaded. Furthe~more, defacti~e or incompatlble products that produce incorrect measurements can be recognized.
The sensor can select a defined filter value in the measuring inst-ument. In the encoding, various circuitry embodiments are possible. First, encoding with a resistor; with this resistor a defined voitage potentlal is genera~ed that is delivered to the microprocessor via A/D converters. The so~t-~are processes the appllcable signal and automatically selects the associated parameters. Second, encoding with ASIC (customer-specific IC); a digitally enciphered signal is generated with the ~SIC and is like~ise delivered to the ~icroprocessor. The microprocessor processes this signal and then again selects the associated parameters. If the code cannot be deciphered by the applicable reader or reader part, then an alarm signal can be tripped. These codes are likewise in.egrated into the catheters and so ~orth, thereby lnsurlng an unequivocal assignment to the sensor tvpe. In other words, the ins~rument (measurinq and/or application and/or monitoring instrument) is capable of unequivocally recognizing the specifically coded electrode, ;
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r~r micropipette, cathet-r, connecting element, and/or measuring and therapy head and may be compatible ~nd ~ence capable of opera~ing only with it. The code can provide the suitably programmed base ~lnit with the following inîormation, for example: electrode manufacturer, electrode type, elect-ode function, operativeness of the electrode, functional status of t~e electrode, location of the electrode, age of the electrode, segment or sector identification on the electrode or catheter, and elec~rode-specific baseline.
With an active code element, it is even possible to encode the measurement signal itself. More simply, it is also possible for some of the measuring electronics, in miniaturized form, to be integrated with the applicable sensor and in par~cular with its measuring tip.
The code element may have a preamplifier, monltoring and cont-ol function and is a component of the measuring and/or application sensor, micropipette, catheter, connecting element, and/or measuring and therapy head. The code element is located in the path between the measuring tip and the instrument and may be mounted direc~ly on the sensor, mic-oplpet~e or catheter, etc., or else is integrated directly with it. It can equally well be a component of the suply or outgoing lead or of a corresponding screw-type, plug-type or bayonet-type connection with the instrument. -t will be understood that the code element may also be a component of the sheathing or jac~et of the eiectrode, micropipette or catheter, and so forth, and has a direct connection with the electrode function, micropipette function or catheter function, or in other words takes on control functions for the particular application.
The advantages of the code are i~mediately apparent and accordina to the inventlon reside in quality assurance, patient ~ ~
safety and reproducibility of the measurements, in particular -`
long-term measurements. In particular, by means of the code, ~ ~
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.
,:. ' . . . : . ' material properties can be de~ined, the location of the electrodes, mic.~pipect2s or ca~he~e~s and so for~~ can be clearly defined, a basis for coordinate capability in multidimensional measured value or measurement subject dis~lay can ~e attained, the electrode-specific measured value range can be automatically defined, limitation of the electrolysis current or stimulation current (organ- or function-specific sa~resuarding) can be achieved, and electrode-specific cali~ration value specifications can be defined. Independently of this, encoding nedical technology utensils opens up further advantageous applications of .
the aids according to the invention. For instance, with the encoded connecting pieces, the leads of conventiGnal H2 explosimeters can be checked and monitored for whether they are correctly sealed. Applications in technical fields, par.icularly in laborator~ technology, vet2rinar~ medicine, etc., for instance in combination with C02 or other sensors, are within the competence of one skilled in tne art. In particular, the measuring apparatus according to the invention can be combined with other equipment, such as eauipment ~or the infusion of liquids and medicines. It will be understood that in this case the measuring elect odes can also be used as sensors for measuring the concentration of applied medications, such as vitamin C complexes, or for monitoring the pH value, glucose value, potassium value, and so forth.
The measuring array shown in Fig. 7 shows a patient 500, who is connected via a coded mask 501 to a hydrogen tank 502. An infusion bottle 504 is connected by suita~le connecting elements `~
to an in~usion needle 504. Measuring sens~rs 506 and a surgical instrument 507 are likewise connected to the measuring instrument 508 via connectina elements with corresponding connection ~ieces.
Implanted sensors 505 are provided with an electromagnetic, readable code. All the utensils and instruments used are likewise ' ., . . ~ . . . . .
'' .; ' ; ' ~,:: ', ~', , :. " , provided ~ith a code ~10.
For long-te~m measurements, sensors with mul~iple electrodes are preferably used, each of the elec~rodes for the measurements being extended from a protective sheath or jacXet.
This jac~et may be of a resorbable material.
In the fur~her .eature, the sensors are provided with means with which the electrodes can be bright sanded prior to each measurement. It will be understood that this process and means ~or it may also be employed `in the technolosical and in industrial fields.
In a proven embodiment, the sensors are connected to the measuring instrument via five-oole electric leads-. In order not to have to provide a separate electric lead for each of the coded elements used, an I2 C-ous circuit, an RS 485, or an ~SB bus system may be used, for instance, or the supply voltage for the -~
actlve coded elements or a cu~~ently commercially available TSS
400 signal processor may be clocked, in order to send the measuring data over the same leads during the sleep mode of the supply voltage. PALs (programmable logic arrays) are also especially suitable for the encoding, because with them it is again possible to make do with merely a two-wire lead. Explicit reference is maàe here to the use of optical leads and electrooptical components for the reading and measuring part of the instrument. The most comfortable embodiment provides for an integrated microprocessor in each case as coded elements. this has recently made it possible to handle data transmission in the form of a logical ring, hereina~ter described as "token ring H2".
The tokPn ring H2 is sent by active participants to active participants in a numerically inc~easing order of -~
partl`cipant addresses, wi.h a token telegram. ~n e~ce2tion is the par_icipant ha~ ng 'he highes_ address; ~ gi~/es a 'oken bac~ to ~-~
the central unit (which has the lowest address), to close the ~ ', :; ''' ' '~
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loglcal ring. ~hen one aclive par~icipant receives a token tQlegram, addressed to it, from its predecessor, then it is allowed to use the token and to handle message c~cles. Its predecessor is determined on the basis of the entries in the list of active stations (LAS), which was generated after power-on in the list-token phase and later is updated continually upon receipt of a token telegram. If the token sender is not the registered predecessor, then the addressee must initially assume that an error has occurred and ignores the token. Not until an ens~ing repetitlon from the same predecessor dces acceptance occu-, leading to token acceptance, since the receiver must assume that the logical ring has changed. The receiver repla~es a list of active stations (L~S) for the originally registe ed predecessors with the new list. After po~er-on, the software of the active participant changes to the list-token state, when it is ready for the logical token ring. In this state, it must listen on the line to ascertain which active participants are already in the logical token ring. To do that, all the token telegrams received are evaluated, and with the participant addresses contained in them the list of active stations (L~S) is generated. .~fter t-~o identical token cycles have been listened to in their entirety, the so~tware s~i l remains in ~his s~ate until it is addressed by its predecessor with a request status. It must acknowledge with the status "rsadv for the ring" and then assume the active state.
If a request status is received during the LAS generation, then it must acknowledge with the status "not ready for the ring". No ;-other telegrams are processed in the list-token state; that is, they are neither acknowledged nor answered. If, in detecting the active participants, the soft~are recognizes its own address in the source address or two token telegrams, then i~ ~ust assume that a part-c~pant having the sa~e acdrQss is a'-eady locatQd in the ring. It must then change to the of~-line state and send a :
~:
... .. ," , ... , , ., ~, - . ,~ ., ~.; .... .
' , , ' ' 'I '' " ~' ' ' ' " '`' ' ' ,, "' ~ ' ' "" '' "''' ' '' repor~ to ~he manage~.nent (cen~~al unit).
If the soft~are perceives no bus activity over a relatively long time, specificall~ during the time-out time, then it must conclude from this that the token was lost and that the logical ring must be rebuilt or restored, and it changes to the claim-token state.
The soft~are assumes the claim-token state after the list-token state or active state if its time-out period has elapsed, if no bus ac~ivitv was ascer_ained dur ng a certain period of time, and if it mus~ be assumed that the token was los.. In that state, an attempt is made to reinitialize the logical ring or to start an initialization. `~
The cent-al unit is accordingly capable at all times of monitoring the nu~ber of active participants using the list of active stations (LAS) and to trip an alarm immediately if there is a change. With the management by means of a token ring as desc-ibed above, the number of participants (hose, connecting piece, sensor, etc.) is not limited to a certain number either, and the various participants can be interconnected in an arbitrary order. ~s a result, it Lollcws that for any conceivable connection, only one processor type is used, always with the same software, which naturall~ si~pliries the manufac_u~ing process considerably. The ~arious components (hose, connecting piece, `~
sensor, etc.) are then me~ely additlonall~t loaded with some component-specific data. These da-ta are stored in the EE~ROM
region of the processor and can accordingly be changed at any time as needed. One possible requirement for change would be a change -~
of parameters because of empirical findings. These new parameters -~ ~
can then be loaced as a ne~ soft~are version (update) to the ~ :
central unit. If components that have not been loaded with the ~OSI recPnt data are ~hen incorpor~ed into the log~cal ring, ~he central unit recognizes this from the version number, which once ~;
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again is stored in memory each time in the processor of the various components, and can then chanqe the ent~ies in the corresponding -~ROM via the token ring as needed. This assures that even components that have not yet been loaded with the most recent parameters can still be used.
The cent-al unit of the measuring instrument is thus capable at any time of monitoring the active codes. In this embodiment, t~e number o~ medical technology components used is not subject to any soft-~are-dictated limitation, and they can be connectad in an arbitrary, that is, non-specified, order and combination without requiring that the software be adapted or changed. Thus not only can basic data of the various medical technology components be detec_ed, but e~piration dates, for instance from preserved blood supplies, can also be stored in memory and evaluated.
It will be understood that the above measuring and monitoring process can also be done in a multiplexing mode or is suitable for controlling medical manipulations, such as taking periodic tissue samples, administering medication, etc.
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The present invention relates to a process for measuringthe blood flow in an organ, partic:ularly in human tissue, employing the hydrogen clearance methcd, and suitable means for performing this process.
Such processes and measuring inst.-uments for it are known in the medical field and serve the pur~os2 of bo~h diagnos~ics and monitoring of the course and success of therapy or of a surgical operation. In this proc~ss, the blood of the su~ject is enriched with hydrogen and used as an electrolyte, which with two electrodes introduced into the tissue to be studied forms a galvanic element. The electrical voltage of this ele~ent is determinedby the concentration of the hydrogen in the blood, among other factors. When this process is employed, the hydrogen is introduced into the blood with the air of respiration or by lnjec~ion. .~s soon as the voltage between the electr~des has attained a ce~ain ii~it value, the delive-y of hyd_ogen is . , .
discontinued and the decrease in voltage as a function of time is ~
observed. The steepness of the ~easured curve of this function is ~-a measure for the tissue blood ~low, in which the hydrogen-enriched blood is re~oved and -sDlaced by hydrogen-f~ee blood.
The theoretical bases of t.iis process, and in particular the calculation or the potentials or the electrodes as a function of the hydrogen ion concentration w~th the aid o~ Nernst's equat on and the determination of the blood flow of a tissue volume from the decrease in concentration of the hydrogen in the blood with `~
the aid of diffusion principles, are described in detail, for instance by ~. Auc.~land e~ ai, in C -culation Research, Vol. ', ~;~
1964, pp. 16~ ff.
Although determining the blood flow of tissue with the aid of inert gases such as hydrogen has been known .or at least 40 ; ; !
years and has been discussed in many ublicaticns, the practical applic~tion of 'his pr~c~ss was prev~ously lim~ed ~o animal experimentation, or to measuring the blood flow rate at the tip of the little finger or a human being. The reasons for this are simple. With the e~uipment previously used to per.orm the process desc~ibed, evaluatable and reproducible measurements could be carried out only if the current intensity bet~een the electrodes and hence in the blood as well, that is, in the tlssue to be stud ed, was at least 1 x 10-6 A, a.value which s vhysiologically objectionable or even impermissible for some ~issues.
One such measuring instrument is described, for instance, in the article entitled "H2 Clearance ~easuremen~ of Blood Flow:
Review of Techni¢ue and Polarographic Principles"; ~ise Young, in STROK~, Vol. 11, No. 5, September-October 1980, pp. 552-564.
~ n appar2tus ~lth which, for the first ti~.e, the determination of tissue blood flow by the advantageous hydrogen clearance method can be used without the measuring current that is physiologically objectionable for human beings is described in ~urovean ~atsnt .~pplicatlon 0 ~52 276, f~r e~amvle.
~ lthough t;~e process desc~i~ed in ~his rarerence is a suitable method for measuring the blood flow in human tissue, it has been found in practice that in long-ter~ measurements, the highly sensitive electrodes required for this process relatively quic.~ly eithe- ~ecvme coatad ~lth endosenous anc especially fibrin-containing substances, or oxidize, thereby impairing the blood flow measurements made over a long period of time.
Another problem arises in the measurement of the spatial distributlon of t~e blood flow in the tissue to be studied, which is especiall~ desirable for long-tarm measurements. In such a measurement, multiple sensors are introduced into the tissue at multiple spa~ially separated points. I- usabia results are ~3 De attained, several measuring instruments, at undesirably high ,. ' . . ~ . .
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expense, are cur_entlv needed to evaluate the measured values scanned ~y the var~ous sensors. Partlcularly in long-ter~
measurements, this spatial measurement is made more difficult by the repeated insertion of new sensors and the calibration of these newly inserted sensors. It is self-evident that inserting new sensors at predetermined points in an organ to be studied involves undesirably high ex?ense for equipment and can be done only by suitably t_ained phvsicians. Particularly, it has also been found that given the great number of measuring electrodes available, technically untrained persons often us~ the wrong electrodes and/or inappropriate elect-odes for the particular equipment, which makes the measurements wrong. ~-In professional circles, the need therefore exists tocreate a process and means for performing this process that do not have these disadvantages and with which process long-term - -measurements in particular can be carried out with high measuring accuracy, in a simple and reliable way, even with spatial measurements. Looking for mistakes during surgery, under sterile external conditions, is flatlv unacce~table.
The object or tne presen~ invention is therefore to c-eate a process for measuring the blood flow by the hydrogen clearance method that overcomes the known disadvantages and in particular makes possible reproduci~le long-term measurements with multiple sensors and hl~hly sare mani~ulation. ~-In particular, the object of the present operating process is to make it possible to monitor whether the various sensors are operative and whether the connection between the measuring instrument and the sensors is proper, and to o~erate these sensors simultaneously wlth a single measuring ins~rument. -This object is attained by the present invention, which envisages a process or the type àiscussed at the outset that has the characteristics recited in the body of claim 1.
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In par~icular, the process ac~ording to ~he inventlon envisages ~he US2 of ' nterc.~angeable sensors of whate~er t~pe, or connecting elements or other medical technology utensils, which are inseparably provided with codes, to enable monitoring their origin, age and type, for lnstance, so that in the assemDled state, in other words, when ready for use, their proper connection can be monitored, or so that they can be operated by a single measuring instrument and/or therapeutic equipment, or in addition to enable ante-ograde and/or retrograde functional control and monitoring.
The advant~ges attained by the invention are substantially the increase in functional reliability and hence~atient safety, particularly from tne monitoring of all the contac~s and functions bet~een the measuring instrument and the arbitrarily disposed sensors, medical technology instruments or utensils; the capability of per~orming long-term measurements with increased accuracy and multidimenslonal aisplay of the measurement values;
quality assurance; and versatility in use made possible by the modular ccns~ruclion.
In addition, the sensors and/or connecting eiements may feed back or transmit stored or measured information. This mode of operation also enables purposeful control of special functions of the sensors.
~ ~easuring inst-ument, or in this cas2 a monitor as ~ell, which is suitable for performing the process of the invention has at least the characteristics recited in present claim 4.
Essentially, the measuring electrode and the reference elec~rode comprise metals whose chemical intrinsic potentlals are close to one another. In order to form the difference between their potentials, both the measuring electrode and the reference electrode are connec~ed via suitable suppl~ leads to the inputs ~f an operational amplifier. The measuring electrode, the reîerenc~
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elec~~ode and ~he neutral elec_-ode, with their supply leads, have shielding agains~ eJ~ternal dis~u_~ance fields. ~o lnduce an opposite potential in the tissue c~mpared with inductively or capacltively coupled potential fluctuations, the shields of the measuring and reference elect~odes and their supply leads are connected on the one hand to the neutr 1 electrode via the positive input of a voltage amplirier circuit, and on the other hand, the negative input of this voltage amplifier circuit is connec'ed to a voltage divider for forming the mean value of the potential of the measuring and reference electrodes that is connected bet-~een t~e suppl~ leads of these electrodes.
For using a plurality of sensors, particul~arly for measuring the spatial dis~ribution of blood flow in an organ, the measuring instrument is preferably equipped with an electronic multiplexer, -~ith which the voltage applied to the various sensors is scanned in succession, for example five times per second. `~
Since the measuring ~art of the instrument is galvanically -separate from the other parts of the instrument, this apparatus maXes it possiole to per~^or~ the hydrogen clearance method for determining ~iood flow using pAysiologically unoojec=ionable ~-~
current intensities and in a reproducible manner. ~ -~ n important factor for safely performing the process is components that carry a code detectable by the aforementioned measuring instrument. These codes may be provided with the aid of electronic, electromagnetic or optical structural elements. It will be understood that to enhance patient safety, these encoded components may be affixed to all the medical technology utensils needed or desired for the study. In any case, however, the sensors necessarv r^or the process of the lnvention and their connecting elements must be inseparably provided with such codes.
~ur-her prererred characteristics of the proces~ according to the invention and of the means for performing this process are recited . ' ; ' ' , ' . , :; ' ; :
. .. . .
in the claims.
The inventicn is desc~ bed in furt~e~ detail below in ter~s of an exemplar~ embodiment.
Shown are:
Fig. 1, a flow chart with the method steps essential to the invention;
Fig. 2, a block circuit diagram of a measuring instrument suitable for performing the process;
Fig. 3, a circuit diagram of the analoq or measuring part of a measuring instrument suitable for.performing the process;
Fig. ~, a more-detailed circuit diagram of the analog or measuring part of a measuring instrument suitable-for performing the process;
Figs. 5a-5q: connection pieces, connecting elements, ox closure elements, of the kind that ar3 suitable for performing the process of the invention;
Figs. 6a-60: sensors of the kind that are suitable for performing the process of the invention;
Fig. 7: one ~ossible ~easuring setup for perfor~inq the process according to the invention.
In Fig. 1, the various steps in the present process are assembled into a flow chart. To measure the spatial distribution of blood flow in a human organ, accord:ing to the invention, in a step a), a plurali_y of detachable, indiv~dually encoded sensors are implanted, in spatially distributed fashion, in a tissue to be studied. As a rule, this step is ca~rie~ out by an experienced .
pAysician. In a second step b), the various sensors, now implanted, are connected via encoded connecting elements to a measuring instrument for deter~ining the blood flow rate by the hydrogen clearance method. Thanks to the present invention, this second step can be carried out even by semis~ lled assistants. In a third step c3, the various code values of the sensors, , ~. . , , . :
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h v ~J ù ~ v connecting 2 lements, and generally o~her medical utensils are read and chec~ed D~r =he ~easu~ing ins~rumen~ a corrQc connection has not been made, then a fault report F is accordingly displayed by the measu~ing instrument. If the monitoring car~ied out by the measuring inst-ument does not lead to a fault report, the measured value detection unit is enabled to detect signals at the measurin~
electrodes. Simultaneously with the measurement d), the measured values, along with the associated code values, are stsred in ~emory, dis?layed, or delivered for evaluation .~.
Particularly once a first measurement has been made, the sensors can be left in the tissue and method step c) can be repeated at regular intervals. After a desired period of time, a further measurement can be made, preferably by the hydrogen clearance method. The measured values of the various measurements are then subjec'ed to evaluation ~. The block ci-cult diagram shown in Fig. 2 shows a power pack 100 that is connected to a power source 200 that has a potQntial lock of at least 4 ~'~ and supplies an analog part 300 with the necessary voltage. The sensors ~ and ~ are connected to the analog part 300. The likewise galvanically separate output of the analog part 300 is connected to a digital part ~00.
For long-term measurements, catheter~ e sensors are implanted, t~rough ~hose cannulas the electrodes necessary for the desired measurement are introduced, preferabiy wi.h a needle.
Depending on the type of electrodes, thev may be removed again and/or replaced after a measurement series has been performed, or unsoiled electrodes can be used for measurement repeate~ly by successively puiling out the needle.
This~flow chart may also be used for other measurement and therapy techniques, such as O~, pH, glucose, potassium, temperature, blood pressure and intrac.anial pressure measurements, as well as for medication-infusion equipment.
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Fig. , s~ows the measuring ~ar~ of a measuring instrument sui~able .or per 3r~1ng the pr~cess~ The measure~ Jalue detection unit 46 is essential to the invention and is connected to a sensor plug 52. TAe ~lxed resistor 54 together with the grounded coding resistor 49 forms a voltage divider whose value is recognized by the measured value detection unit 46. In this embodiment, the measuring elect.ode 11, shielded at 25 from external dis.urbance potentials, is connec_ed via a supply lead 12 to a first impedance converter '~, whose output is conne~ted to t~e negati-~e input of a measuring amplifier 13. A reference electrode 15~ shielded at 27, is connected via a supply lead 17 to a second i~pedance converter 16, whose output is connected to the positive input of the measuring amplifier 13 via a resistor that is variable for zero balancing. The measuring instrument used preferentially for the process of the invention also has a driving neut_al elect~ode 29, with which opposed fields are actively coupled into the measuring reason in order to compensate .or external disturbing fields. To that end, the mean value of all the signals from the voltage divider 31 is kept at 0 V Dy varying the common grour.d. The ground feedback via the two inverting amplifiers 28 or via a PI
controller is done with high impedance, for instance with an impedance of lO0 kn. The supply lead 24 for the disturbance voltages is ln communication with the shields 25, 27. The output of the differential amplifier 13 is connected to an analog/digital converter 46 via a low-pass filter. The component 46 shown in Fig. 3 detects six signals and has a 10-byte resolution (1024 component). Triggerlng on the digital side is done by a microprocessor 41 via a data bus ~l having at least four leads ~hat are connected Vi2 optical couplers 7 to the A/D converter 46. For the supply, a suitable repeating coil 48 is provided.
It will be understood that even h-gher-resolution components, such as a 4096 (12 byte) component may be used. The . , : . .. ,, : .
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free analog inputs 33, ~O c~n then derec~ fur her signals, such as pH ~a ue, te-nper2tlrQ, or codes. 'iia ~he four dlgital leads ~1, signals can be t-ans,erred to the analog part simply, using the same connections. The transfer is done serially and may be expanded at will. ror instance, the capability exists of controlling the cur,ent for H2 production, per-orming a switchover of measurement range, or of varying OFFSET and amplificatlon is signal detection. The digital par, primarily comprlses the processor 41, whose program `is stored in an EP~OM of the memory 42. A timer and an 8- to 32-kilobyte RAM memory is also provided, whose operation is backed up with a built-in battery. In the R~, a plurality of measurements can be stored and cal-led up again later. The inter~ace components for the display 43; serial interface 45, keyboard 44 and converters are well-known to one skilled in the ar'. For the display, LC~s or complete monitors can be used equally well. Acoustical warning signals may be built in without any inventive erfort.
In a proven embodiment, the voltage of the sensors is measured ~ ~ mes pe~ second. ~he current value is calcula_2d f~om that and shown in the display. In addition, the signal or the sensor is read and stored in the nonvo:Latile memory and made available for evaluation. Preferably, for further illumination of disturbances in the measured values, the mean value of the exponential regression is calculat-d rrom ~ to 10 measured values.
This a~paratus is eaually suitable for flow measurement in veterinary medicine, in laboratory work, and for industrial applications.
Fig. 4 shows the circuit diagram of the analog or measuring part ~or t-~o coded sensors, in detail. The sensors are connected to the instrument by a multipole plastic plu~ connection and a highly flexlble, sAielded sensor cable. Each of these parts has a special code, which can be recognized by the instrument.
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~ u ~ ~, ) u ~a Figs. a-~q show varlous embodiments for connection pieces and connec~ing ele~e.~s or clos~re e ements of the ~ind needed to perform the process of the invention. Connection pieces and connecting ele~ents of this kind and other are well-known in medical technology and according to the invention are provided with an electronically detectable code, or in other words if - necessary include at least one shielded elect~ic~l lead ~ith a suita~le contac_ point for producing an electrical connection bet~een a code reader unit, which is independent cr lntegrated into the m~asuring instrument, and the code-carrying element, which is embodied for instance of a resistor element, a microchip, or other elec~_onic components having a definable-value or state.
Figs. 6a-60 show examples of sensors and in par~icular electrode carriers, of the kind that are possible for performing the process of .he invention. Since in practical ter~s the area of potential use in medicine is unlimited, the-sensors also have a great many forms and properties. The following list is therefore limited merely to several basic types, which in their embodiment can naturally ce r~adily adapted ~3 e.Yi sting needs. In the variant shown in Figs. 6f, 6g, 6k and 61, each electrode or each measuring and/or therapy head is guided individually. ~s a result of this embodi~ent, it is possible to place the various electrodes locally independently. The result is accordingly three individual electrode carriers with the associated electrode materials.
In the variant of Fig. 6m, the electrodes are combined in one sensor. ~s a result of this embodlment, all the electrodes are placed ~t the same location. The result is accordingly only a single sensor, with the associated elec__ode materials. This specialized emDodiment even makes i- possible to expose only the sensitive measu-ing electrodes for the desired measurement, and then to retrac_ them back into the protective sheath again.
In the variant of Figs. 6a and 6n, a plurality of :: " . : : . . . : ::
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.
elec'~odes are c~ined in one sensor. Thls embodi~ent makes three-dlme~siona me~surement possibla. Accor~in~ly, ~here is only a sin~le sensor with the associated electrode materials.
In the variant of Fig. 6i, a plurality of elect-odes of the same electrode ma~2rial are accommodated in one senscr. This embodiment maXes three-dimensional area measurement possible. The result is accordingly one area sensor with a plurality of measuring elect~odes, and one neutral and one driving electrode each, along ,iit~. the associa`ted e~ec.rode mate~ials.
It will be understood that all possible forms may be used as the electrodes, for instance of the kind al~eady Xnown as membrane-covered elect-odes, implantable electrodes for H2, 2 or bioelectrical slgnals, stick-on electrodes, surface electrodes, one-way electrodes, needle electrodes, brush electrodes, disk mic.oelectrod2s, thin-film electrodes, and 3-D elect~odes. These electrodes can equally well be integrated into ultrasound sensors or catheters, such as venous catheters, central venous catheters, arterial catheters, cardiac catheters, balloon catheters, shunt meas~_ing ca_:~ete's, s'anosis meas~r ng c~thet~rs, liver catheters, Port-a-cath catheters, intrac~anial pressure catheters, drainage catheters, kidney~urine catheters, sensor catheters (for temperature, blood pressure, H2, 2~ etc), or in biopsy and aspiration instruments, of ~he kind also shown in Figs. 50-5q and 6a-6e. Examples of elect-ode mat~rials ~hat have proved particularly suitable for the measurin~ tip are the following:
platinum, silver~silver chloride, silver, platinum-iridium, iridium, platinum-iridium-based, film electrodes, platinum-~lack-covered, microelectrodes, multibarreled electrodes, mic-opipette electrodes, tlngsten, tungs'en glass fibers, platinum-rhodium-quartz fibers, tantalum-on-sapphire multielectrodes, platinum-tantalum polyimides, and metal-noble met~is. The suDstrate materials preferably used are polyamide, p+-type silicone, n-type .: .: ~ .
.
' '' ' ' ' `'" ~,'' ' ' ' ' ';. ~ " ~ ` ' .' '' , ' " ' ' ' ` ' ' silicone, silicone rubbers, Kapton (polyimide), ?yrex, Teflon, Tri-.~ll insuia~- sil~er ~ire, Dac~on-.~esh matri~, car~on, polyethylene, polyethylene glycol, polyurethane, borosilicates, epoxy resin, Hysol epoxy, Epoxylite, cyanoacrylate, stainless steel, Silast c, Parylene-N, polystyrene, polyepichlorohydrin, cellulose acetate membrane, and PVC membrane.
The sensors or therapy heads may also have t- nsistors or other sensors as well as controllable valves.
~ li the sensors used in connection with the _lcod flow measuring instrument have integrated sensor detection. This encoding has the advantage that the instrument automacically recognizes the ap~licable sensor type, so that sensor-specific and measurement-type-speciflc soft~are can be loaded. Furthe~more, defacti~e or incompatlble products that produce incorrect measurements can be recognized.
The sensor can select a defined filter value in the measuring inst-ument. In the encoding, various circuitry embodiments are possible. First, encoding with a resistor; with this resistor a defined voitage potentlal is genera~ed that is delivered to the microprocessor via A/D converters. The so~t-~are processes the appllcable signal and automatically selects the associated parameters. Second, encoding with ASIC (customer-specific IC); a digitally enciphered signal is generated with the ~SIC and is like~ise delivered to the ~icroprocessor. The microprocessor processes this signal and then again selects the associated parameters. If the code cannot be deciphered by the applicable reader or reader part, then an alarm signal can be tripped. These codes are likewise in.egrated into the catheters and so ~orth, thereby lnsurlng an unequivocal assignment to the sensor tvpe. In other words, the ins~rument (measurinq and/or application and/or monitoring instrument) is capable of unequivocally recognizing the specifically coded electrode, ;
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' . ' .
! , . .
r~r micropipette, cathet-r, connecting element, and/or measuring and therapy head and may be compatible ~nd ~ence capable of opera~ing only with it. The code can provide the suitably programmed base ~lnit with the following inîormation, for example: electrode manufacturer, electrode type, elect-ode function, operativeness of the electrode, functional status of t~e electrode, location of the electrode, age of the electrode, segment or sector identification on the electrode or catheter, and elec~rode-specific baseline.
With an active code element, it is even possible to encode the measurement signal itself. More simply, it is also possible for some of the measuring electronics, in miniaturized form, to be integrated with the applicable sensor and in par~cular with its measuring tip.
The code element may have a preamplifier, monltoring and cont-ol function and is a component of the measuring and/or application sensor, micropipette, catheter, connecting element, and/or measuring and therapy head. The code element is located in the path between the measuring tip and the instrument and may be mounted direc~ly on the sensor, mic-oplpet~e or catheter, etc., or else is integrated directly with it. It can equally well be a component of the suply or outgoing lead or of a corresponding screw-type, plug-type or bayonet-type connection with the instrument. -t will be understood that the code element may also be a component of the sheathing or jac~et of the eiectrode, micropipette or catheter, and so forth, and has a direct connection with the electrode function, micropipette function or catheter function, or in other words takes on control functions for the particular application.
The advantages of the code are i~mediately apparent and accordina to the inventlon reside in quality assurance, patient ~ ~
safety and reproducibility of the measurements, in particular -`
long-term measurements. In particular, by means of the code, ~ ~
:~ .
' , ~ ,. .
.'",. ' ' .. ''' ,' ' ' '.. '' ~ ' ~ I,.
.
,:. ' . . . : . ' material properties can be de~ined, the location of the electrodes, mic.~pipect2s or ca~he~e~s and so for~~ can be clearly defined, a basis for coordinate capability in multidimensional measured value or measurement subject dis~lay can ~e attained, the electrode-specific measured value range can be automatically defined, limitation of the electrolysis current or stimulation current (organ- or function-specific sa~resuarding) can be achieved, and electrode-specific cali~ration value specifications can be defined. Independently of this, encoding nedical technology utensils opens up further advantageous applications of .
the aids according to the invention. For instance, with the encoded connecting pieces, the leads of conventiGnal H2 explosimeters can be checked and monitored for whether they are correctly sealed. Applications in technical fields, par.icularly in laborator~ technology, vet2rinar~ medicine, etc., for instance in combination with C02 or other sensors, are within the competence of one skilled in tne art. In particular, the measuring apparatus according to the invention can be combined with other equipment, such as eauipment ~or the infusion of liquids and medicines. It will be understood that in this case the measuring elect odes can also be used as sensors for measuring the concentration of applied medications, such as vitamin C complexes, or for monitoring the pH value, glucose value, potassium value, and so forth.
The measuring array shown in Fig. 7 shows a patient 500, who is connected via a coded mask 501 to a hydrogen tank 502. An infusion bottle 504 is connected by suita~le connecting elements `~
to an in~usion needle 504. Measuring sens~rs 506 and a surgical instrument 507 are likewise connected to the measuring instrument 508 via connectina elements with corresponding connection ~ieces.
Implanted sensors 505 are provided with an electromagnetic, readable code. All the utensils and instruments used are likewise ' ., . . ~ . . . . .
'' .; ' ; ' ~,:: ', ~', , :. " , provided ~ith a code ~10.
For long-te~m measurements, sensors with mul~iple electrodes are preferably used, each of the elec~rodes for the measurements being extended from a protective sheath or jacXet.
This jac~et may be of a resorbable material.
In the fur~her .eature, the sensors are provided with means with which the electrodes can be bright sanded prior to each measurement. It will be understood that this process and means ~or it may also be employed `in the technolosical and in industrial fields.
In a proven embodiment, the sensors are connected to the measuring instrument via five-oole electric leads-. In order not to have to provide a separate electric lead for each of the coded elements used, an I2 C-ous circuit, an RS 485, or an ~SB bus system may be used, for instance, or the supply voltage for the -~
actlve coded elements or a cu~~ently commercially available TSS
400 signal processor may be clocked, in order to send the measuring data over the same leads during the sleep mode of the supply voltage. PALs (programmable logic arrays) are also especially suitable for the encoding, because with them it is again possible to make do with merely a two-wire lead. Explicit reference is maàe here to the use of optical leads and electrooptical components for the reading and measuring part of the instrument. The most comfortable embodiment provides for an integrated microprocessor in each case as coded elements. this has recently made it possible to handle data transmission in the form of a logical ring, hereina~ter described as "token ring H2".
The tokPn ring H2 is sent by active participants to active participants in a numerically inc~easing order of -~
partl`cipant addresses, wi.h a token telegram. ~n e~ce2tion is the par_icipant ha~ ng 'he highes_ address; ~ gi~/es a 'oken bac~ to ~-~
the central unit (which has the lowest address), to close the ~ ', :; ''' ' '~
.~ , ' .
..... .
.' : , , . ' , :
:-' ' ' ., ., - . : . .
- . :. :. . .. . . ..
,:. ~ ~ : . . :: .
loglcal ring. ~hen one aclive par~icipant receives a token tQlegram, addressed to it, from its predecessor, then it is allowed to use the token and to handle message c~cles. Its predecessor is determined on the basis of the entries in the list of active stations (LAS), which was generated after power-on in the list-token phase and later is updated continually upon receipt of a token telegram. If the token sender is not the registered predecessor, then the addressee must initially assume that an error has occurred and ignores the token. Not until an ens~ing repetitlon from the same predecessor dces acceptance occu-, leading to token acceptance, since the receiver must assume that the logical ring has changed. The receiver repla~es a list of active stations (L~S) for the originally registe ed predecessors with the new list. After po~er-on, the software of the active participant changes to the list-token state, when it is ready for the logical token ring. In this state, it must listen on the line to ascertain which active participants are already in the logical token ring. To do that, all the token telegrams received are evaluated, and with the participant addresses contained in them the list of active stations (L~S) is generated. .~fter t-~o identical token cycles have been listened to in their entirety, the so~tware s~i l remains in ~his s~ate until it is addressed by its predecessor with a request status. It must acknowledge with the status "rsadv for the ring" and then assume the active state.
If a request status is received during the LAS generation, then it must acknowledge with the status "not ready for the ring". No ;-other telegrams are processed in the list-token state; that is, they are neither acknowledged nor answered. If, in detecting the active participants, the soft~are recognizes its own address in the source address or two token telegrams, then i~ ~ust assume that a part-c~pant having the sa~e acdrQss is a'-eady locatQd in the ring. It must then change to the of~-line state and send a :
~:
... .. ," , ... , , ., ~, - . ,~ ., ~.; .... .
' , , ' ' 'I '' " ~' ' ' ' " '`' ' ' ,, "' ~ ' ' "" '' "''' ' '' repor~ to ~he manage~.nent (cen~~al unit).
If the soft~are perceives no bus activity over a relatively long time, specificall~ during the time-out time, then it must conclude from this that the token was lost and that the logical ring must be rebuilt or restored, and it changes to the claim-token state.
The soft~are assumes the claim-token state after the list-token state or active state if its time-out period has elapsed, if no bus ac~ivitv was ascer_ained dur ng a certain period of time, and if it mus~ be assumed that the token was los.. In that state, an attempt is made to reinitialize the logical ring or to start an initialization. `~
The cent-al unit is accordingly capable at all times of monitoring the nu~ber of active participants using the list of active stations (LAS) and to trip an alarm immediately if there is a change. With the management by means of a token ring as desc-ibed above, the number of participants (hose, connecting piece, sensor, etc.) is not limited to a certain number either, and the various participants can be interconnected in an arbitrary order. ~s a result, it Lollcws that for any conceivable connection, only one processor type is used, always with the same software, which naturall~ si~pliries the manufac_u~ing process considerably. The ~arious components (hose, connecting piece, `~
sensor, etc.) are then me~ely additlonall~t loaded with some component-specific data. These da-ta are stored in the EE~ROM
region of the processor and can accordingly be changed at any time as needed. One possible requirement for change would be a change -~
of parameters because of empirical findings. These new parameters -~ ~
can then be loaced as a ne~ soft~are version (update) to the ~ :
central unit. If components that have not been loaded with the ~OSI recPnt data are ~hen incorpor~ed into the log~cal ring, ~he central unit recognizes this from the version number, which once ~;
; . . , . ~
. . . ~ :,, ~ . .: :
.
,,: ~, ,, ~: . . : . :. , , ~, .: , . .. . . . . .
:: : : :.: :
~':': ' . : : , :.
.. . . . .
again is stored in memory each time in the processor of the various components, and can then chanqe the ent~ies in the corresponding -~ROM via the token ring as needed. This assures that even components that have not yet been loaded with the most recent parameters can still be used.
The cent-al unit of the measuring instrument is thus capable at any time of monitoring the active codes. In this embodiment, t~e number o~ medical technology components used is not subject to any soft-~are-dictated limitation, and they can be connectad in an arbitrary, that is, non-specified, order and combination without requiring that the software be adapted or changed. Thus not only can basic data of the various medical technology components be detec_ed, but e~piration dates, for instance from preserved blood supplies, can also be stored in memory and evaluated.
It will be understood that the above measuring and monitoring process can also be done in a multiplexing mode or is suitable for controlling medical manipulations, such as taking periodic tissue samples, administering medication, etc.
.-:
,, :: .. , . :
: , . .: :: : :
Claims (21)
1. A process for operating a medical technology apparatus, in particular for measuring the blood flow in an organ, preferably in human tissue, using the hydrogen clearance method, characterized in that a) at least one detachable, coded sensor having at least one electrode or measuring head is placed in the region of a tissue to be studied, b) the coded sensor is connected to a suitable instrument and in particular is connected to this instrument via at least one coded connecting element, c) the at least one code value of the at least one code is read and checked by the measuring instrument, d) not until checking of the at least one code value has been done is at least one first measurement performed, and e) the at least one measured value, together with the at least one associated code value, is stored in memory, displayed, or sent for evaluation.
2. The process of claim 1, characterized in that once a first measurement has been done, the at least one sensor is left in the tissue, process step c) is repeated at regular time intervals, after a desired period of time, at least one second measurement is performed.
3. The process of claim 2, characterized in that for the second measurement, unused electrodes or measuring heads are put in the region of the tissue to be studied.
?
?
4. A measuring instrument suitable for performing the process defined by claim 1, with a supply, with an analog or measuring part and a digital part for evaluation and display, which measuring or therapy part has at least one sensor with at least one electrode, characterized in that the measuring instrument includes means for generating a potential in the tissue to be studied that is the opposite of inductively or capacitively coupled-in potential fluctuations, and that the measuring instrument has means for reading, checking and storing in memory a code connected to at least one of the sensors or connecting elements.
5. The measuring instrument of claim 4, characterized in that the analog or measuring part includes a measured value and code value detection unit, which periodically scans the signals of the at least one sensor or connecting element.
6. The measuring instrument of claim 5, characterized in that the measuring or therapy part has at least one detachable sensor.
7. The measuring instrument of claim 5, characterized in that the analog or measuring part is galvanically separated from the other parts of the instrument.
8. A connecting element suitable for performing the process defined by claim 1, characterized in that the connecting element has at least one code recognizable by an associated code value detection unit.
9. The connecting element of claim 6, characterized in that the connecting element is part of a medical technology utensil.
10. The connecting element of claim 6, characterized in that the recognizable code is formed by an electrical resistor element.
11. The connecting element of claim 6, characterized in that the recognizable code is formed by a microchip.
12. The connecting element of claim 6, characterized in that the recognizable code is formed by a transponder.
13. The connecting element of claim 6, characterized in that the recognizable code is formed by an electrooptical component.
14. A sensor suitable for performing the process of claim 1, having an electrode or measuring head carrier and at least one electrode or measuring head substrate, characterized in that the sensor has at least one code recognizable by an associated code value detection unit.
15. The sensor of claim 12, characterized in that the recognizable code is formed by an electrical resistor element.
16. The sensor of claim 12, characterized in that the recognizable code is formed by a microchip.
17. The sensor or claim 12, characterized in that the recognizable code is formed by a transponder.
18. The sensor of claim 12, characterized in that the recognizable code is formed by an electrooptical component.
19. The sensor of one of claims 13-16, characterized in that the electronics of the measured value and/or code value detection unit are at least partially located in a sensor.
20. The sensor of claim 12, characterized in that the electrode or measuring head carrier is a medical technology instrument.
21. The sensor of claim 12, characterized in that the sensor has a plurality of electrodes or measuring heads.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH286091 | 1991-09-26 | ||
| CH2860/91-8 | 1991-09-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2096836A1 true CA2096836A1 (en) | 1993-03-27 |
Family
ID=4243212
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002096836A Abandoned CA2096836A1 (en) | 1991-09-26 | 1992-09-25 | Medico-technical process and means for measuring blood irrigation of organs |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US5830129A (en) |
| EP (1) | EP0566710A1 (en) |
| JP (1) | JPH06507815A (en) |
| AU (2) | AU667055B2 (en) |
| CA (1) | CA2096836A1 (en) |
| FI (1) | FI932354A (en) |
| NO (1) | NO931879L (en) |
| WO (1) | WO1993005700A1 (en) |
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| US6298255B1 (en) * | 1999-06-09 | 2001-10-02 | Aspect Medical Systems, Inc. | Smart electrophysiological sensor system with automatic authentication and validation and an interface for a smart electrophysiological sensor system |
| US20060095032A1 (en) | 1999-11-16 | 2006-05-04 | Jerome Jackson | Methods and systems for determining physiologic characteristics for treatment of the esophagus |
| US20040215235A1 (en) | 1999-11-16 | 2004-10-28 | Barrx, Inc. | Methods and systems for determining physiologic characteristics for treatment of the esophagus |
| WO2001035846A1 (en) | 1999-11-16 | 2001-05-25 | Ganz Robert A | System and method of treating abnormal tissue in the human esophagus |
| DE10155886B4 (en) * | 2001-11-14 | 2006-07-13 | Endress + Hauser Conducta Gesellschaft für Mess- und Regeltechnik mbH + Co. KG | Automatable measuring, cleaning and / or calibration device for electrodes for measuring ph values or redox potentials |
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| US7811231B2 (en) | 2002-12-31 | 2010-10-12 | Abbott Diabetes Care Inc. | Continuous glucose monitoring system and methods of use |
| DE10344263A1 (en) * | 2003-09-23 | 2005-05-12 | Conducta Endress & Hauser | Method for secure data transmission between an intrinsically safe sensor and a non-intrinsically safe evaluation unit |
| US7150745B2 (en) | 2004-01-09 | 2006-12-19 | Barrx Medical, Inc. | Devices and methods for treatment of luminal tissue |
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| CA2683721C (en) | 2007-04-14 | 2017-05-23 | Abbott Diabetes Care Inc. | Method and apparatus for providing dynamic multi-stage signal amplification in a medical device |
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| US8456301B2 (en) | 2007-05-08 | 2013-06-04 | Abbott Diabetes Care Inc. | Analyte monitoring system and methods |
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| US8251992B2 (en) | 2007-07-06 | 2012-08-28 | Tyco Healthcare Group Lp | Method and apparatus for gastrointestinal tract ablation to achieve loss of persistent and/or recurrent excess body weight following a weight-loss operation |
| KR101547931B1 (en) | 2007-07-06 | 2015-08-28 | 코비디엔 엘피 | Ablation in the gastrointestinal tract to achieve hemostasis and eradicate lesions with a propensity for bleeding |
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-
1992
- 1992-09-25 AU AU25898/92A patent/AU667055B2/en not_active Ceased
- 1992-09-25 WO PCT/CH1992/000194 patent/WO1993005700A1/en not_active Application Discontinuation
- 1992-09-25 EP EP92919928A patent/EP0566710A1/en not_active Withdrawn
- 1992-09-25 JP JP5505670A patent/JPH06507815A/en active Pending
- 1992-09-25 CA CA002096836A patent/CA2096836A1/en not_active Abandoned
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1993
- 1993-04-01 US US08/380,313 patent/US5830129A/en not_active Expired - Fee Related
- 1993-05-24 NO NO93931879A patent/NO931879L/en unknown
- 1993-05-24 FI FI932354A patent/FI932354A/en not_active Application Discontinuation
-
1996
- 1996-01-25 AU AU42205/96A patent/AU4220596A/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| FI932354A0 (en) | 1993-05-24 |
| US5830129A (en) | 1998-11-03 |
| WO1993005700A1 (en) | 1993-04-01 |
| NO931879D0 (en) | 1993-05-24 |
| AU4220596A (en) | 1996-06-06 |
| JPH06507815A (en) | 1994-09-08 |
| AU667055B2 (en) | 1996-03-07 |
| FI932354A (en) | 1993-05-24 |
| NO931879L (en) | 1993-05-24 |
| EP0566710A1 (en) | 1993-10-27 |
| AU2589892A (en) | 1993-04-27 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Discontinued |