[go: up one dir, main page]

WO1993017627A1 - Dispositif de surveillance ameliore pour elements de protection chirurgicaux - Google Patents

Dispositif de surveillance ameliore pour elements de protection chirurgicaux Download PDF

Info

Publication number
WO1993017627A1
WO1993017627A1 PCT/US1993/001853 US9301853W WO9317627A1 WO 1993017627 A1 WO1993017627 A1 WO 1993017627A1 US 9301853 W US9301853 W US 9301853W WO 9317627 A1 WO9317627 A1 WO 9317627A1
Authority
WO
WIPO (PCT)
Prior art keywords
electrical condition
rate
value
detection circuit
change
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.)
Ceased
Application number
PCT/US1993/001853
Other languages
English (en)
Inventor
Robert E. Williams
William H. Marshall
Mark Maxham
John K. Bennett
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Novatec Medical Products Inc
Original Assignee
Novatec Medical Products Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Novatec Medical Products Inc filed Critical Novatec Medical Products Inc
Priority to AU37840/93A priority Critical patent/AU3784093A/en
Priority to BR9306029A priority patent/BR9306029A/pt
Priority to JP5515828A priority patent/JPH08504265A/ja
Publication of WO1993017627A1 publication Critical patent/WO1993017627A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/40—Investigating fluid-tightness of structures by using electric means, e.g. by observing electric discharges
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B42/00—Surgical gloves; Finger-stalls specially adapted for surgery; Devices for handling or treatment thereof
    • A61B42/30—Devices for detecting perforations, leaks or tears
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M3/00—Investigating fluid-tightness of structures
    • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
    • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
    • G01M3/16—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means
    • G01M3/18—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators
    • G01M3/186—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators for containers, e.g. radiators
    • G01M3/187—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators for containers, e.g. radiators for flexible or elastic containers

Definitions

  • This invention relates to the detection of adulteration of critical use articles, such as gloves used during surgery or other medical procedures, condoms, surgical gowns, or other barriers, in order to detect this adulteration as soon as technically possible.
  • This early detection reduces the risk of exposure of the wearer of the invention to the body fluids of patients. Early detection further protects patients from the body fluids of the person wearing the gloves.
  • Background of the Invention The adulteration of critical use articles such as surgical gloves and condoms poses considerable health risks.
  • Adulteration as used herein is intended to encompass conditions such as holes formed during manufacture of the article as well as holes formed thereafter for any reason, which holes provide a path for adulteration of the article by potentially dangerous fluids such as body fluids.
  • holes includes not only holes capable of initially passing fluid but also incipient holes, which may, initially, be too small to pass amounts of fluid but may enlarge over time, or otherwise breach or deteriorate the integrity of the barrier posed by the article. Such holes may even form a danger before reaching a size large enough to pass actual fluid since bacteria may theoretically pass through even smaller openings; but, it is more likely that a fluid carrier is needed to carry the bacteria through the membrane.
  • a critical use article is the surgical glove. Although problems associated with surgical gloves are discussed below, it is understood that similar problems are presented by other articles such as condoms, surgical gowns, surgical drapes, etc.
  • the water fill test is only capable of detecting holes large enough to pass visually detectable amounts of water. Danger exists when a hole is large enough to expose skin on the other side of the glove to harmful bacteria or virus even though the hole may not be large enough to actually allow visible amounts of water to pass through the hole during the water fill test.
  • the second source of holes or perforations in gloves occurs during use. For example, holes or dangerously thin spots may develop in gloves at the time that the surgeon first fits the gloves over his or her hands, or, a glove may be perforated during surgery. Perforations during surgery can occur because of penetration by sharp objects or because of the breaking down of inherently thin spots in the gloves or areas made thin as a result of putting the glove on the hand or manipulating instruments. Perforations expose the surgeon to actual or possible contact with patient body fluids because of the resulting adulteration of the surgical gloves.
  • the problem with the AIDS virus is not limited, however, to surgeons or other persons in the operating room such as nurses and anesthesiologists.
  • surgeons or other persons in the operating room such as nurses and anesthesiologists.
  • other users of critical use gloves such as dentists or paramedics may be subject to many of the same serious concerns because the dentist or paramedic is also exposed to body fluids during his or her work on a patient. While perhaps less likely, there is also some possibility for the spread of serious diseases from patients to doctors during physical examinations.
  • U.S. Patent No. 4,321,925 of John Hoborn and Ulrich Krebs discloses an electronic detector arranged so that the level of electronic conductivity through the gloves and between the patient and the surgeon may be sensed at regularly recurring discrete time intervals in order to measure a predetermined level of sensed conductivity and signal an alarm if such predetermined level is met.
  • the detecting circuit of the , 925 patent is actually located in one of the shoes of the surgeon and includes one contact located in the insole of the shoe in order to make electrical contact with the surgeon and a second contact exposed to an electrically conducting plate located on the floor of the operating room so that a closed circuit is formed between the operating table, the patient, the doctor, the electronic device located in the shoe and the round conducting element or plate located on the floor of the operating room.
  • the '925 patent teaches that five times per second the disclosed circuit short-circuits the contacts in the insole and in the bottom of the sole of the shoe in order to discharge static electricity from the insole contact which may have accumulated from the doctor. After each shor circuit, the circuit is opened between the two contacts and a voltage level sensor is used to detect the level of electrical conductivity which occurs externally between the contacts.
  • the impedance of the rubber or latex that comprises the surgical gloves is high. If there is a perforation in the operating gloves of the surgeon, the impedance is thereby reduced and a greater conductivity is provided through the gloves.
  • the '925 patent teaches that the occurrence of a perforation in the operating gloves may result in a relatively high electric conductivity between the surgeon and patient, thus allowing the sensing device to sound an alarm upon the occurrence of a predetermined level of sensed conductivity.
  • the level of conductivity required to trigger the alarm may differ from glove to glove, depending upon the nature of the material, the thickness of the material and any other factors which may impact upon the general conductivity of the series circuit, which includes not only the doctor and patient, but also the doctor's shoes, a round plate located on the operating floor, and the operating table itself. Therefore, the '925 patent may work fairly well for certain types of gloves whose characteristics conform to the particular resistance level chosen for the resistance level sensor, but the '925 patent may not work well with many other types of gloves. In order to function properly, the resistance level sensor in the '925 patent would have to be adjusted to some pre ⁇ determined level depending on the type of gloves used.
  • the present invention comprises a new and improved monitoring device for detection of holes in gloves and other barriers.
  • the monitoring device according to the present invention can reliably monitor the integrity of gloves for an extended period of time and is suitable for use with a number of different glove types from different glove manufacturers.
  • the monitoring device is a programmable, configurable, and self-adapting device.
  • the device continuously measures the resistance, the rate of change or first derivative of resistance, and the rate of change or second derivative of resistance across the gloves worn by the health care worker in a circuit comprised of the patient, the health care worker, and the gloves.
  • the device distinguishes between changes in resistance caused by a hole or puncture in the glove and changes in resistance caused by normal glove hydration.
  • the device When the system is turned on, a number of variables are initialized and the device is configured to a certain risk level. On certain high risk operations, the configuration of certain variables can be adjusted so that the alarm is activated more easily and therefore detects an even smaller adulteration than does the standard configuration.
  • the device continually monitors the voltage level applied across the gloves and performs an autorange function to maintain the voltage level in a desired range, where the devices measurement capability is most acute.
  • the autorange function ensures that, as the gloves become hydrated due to use, the current supplied across the gloves is adjusted upward accordingly to maintain the voltage level in the prescribed range. This significantly increases the length of time that the gloves can be reliably monitored.
  • the device continuously monitors the resistance across the gloves in the presence of substantial amounts of electrical noise and executes a smoothing function across the obtained resistance values using a combination of linear and non-linear filters.
  • These software filters improve the reliability of the system by decreasing the possibility of erroneous resistance values causing false alarms.
  • the linear filters employ averaging, and the non-linear filter employs a 5-point median filter.
  • the device computes the first and second derivatives of the resistance across the gloves and uses these values to aid in determining if a hole or puncture condition is likely to have occurred.
  • the device preferably operates such that, if the resistance across the gloves drops below a certain threshold value, referred to as the ARMING POINT and either the first or second derivative values of the resistance across the gloves indicate that a puncture condition may have occurred, the device enters an ARMED condition, indicating that the first step has been taken toward sounding the hole alarm. If the device is armed, and if the resistance across the gloves then drops below a second critical threshold value referred to as the HOLE POINT, then the END-OF-USE ALARM is sounded.
  • the END-OF-USE ALARM is primarily an indicator of a hole or puncture in the glove, but may also be signalled when the glove is unsafe to wear due to the risk of shock hazard to health care workers.
  • the device is ARMED for a period of time greater than a preset value, and the resistance does not drop below the HOLE POINT, then the device is disarmed, it being assumed that the armed condition did not represent a breach in the glove barrier, but rather a period of rapid hydration.
  • HYDRATION POINT a certain minimum value referred to as HYDRATION POINT
  • HYDRATION POINT a certain minimum value referred to as ARMED
  • END-OF-USE WARNING is an advisory signal that warns of a glove condition requiring regloving in the near future. This gives the health care worker time to plan to reglove when most convenient and when patient safety permits.
  • this invention comprises a device that continually monitors the resistance across a pair of gloves, as well as the first and second derivatives of resistance, to detect punctures or holes in the gloves.
  • the device continually monitors and adjusts the current generated through the gloves as the' gloves become hydrated over time to increase the length of time that gloves can be reliably monitored. When the resistance across the gloves drops below a certain warning value, then the surgeon is advised that the gloves should be changed. It should be noted that one distinguishing feature of the present invention over all other prior art devices is that, even if a glove gradually hydrates below some predetermined resistance level that would at least theoretically alarm prior art devices, the device according to the present invention will not signal an END-OF-USE ALARM.
  • the device according to the present invention requires a rapid drop in resistance (large first or second derivative) immediately prior to reaching a predetermined low resistance level in order to activate the END-OF-USE ALARM.
  • the monitoring device generates pulses of time-varying current, either AC or pulsating DC, across the gloves or other barrier being tested. This allows the electrical characteristics , in particular the resistance and capacitive reactance components of the barrier impedance, of the gloves or barrier to be fully characterized, thus providing enhanced testing accuracy.
  • Figure 1 is a block diagram of the glove monitoring device according to the preferred embodiment of the invention
  • Figures 2A-D are flowchart diagrams illustrating operation of the monitoring device of Figure 1;
  • Figures 3A-F are various graphs illustrating resistance and the first and second derivatives of resistance across the gloves versus time during various conditions of hydration and puncture.
  • Figures 4A-D are flowchart diagrams illustrating operation of the monitoring device according to a second embodiment of the invention.
  • the monitoring device is used to monitor the condition of surgical gloves.
  • the monitoring device can be used to monitor the condition of other articles that act as a barrier between persons to prevent the transmission of bodily fluids or other dangerous fluids.
  • the monitoring device can be used to monitor other articles including, but not limited to, condoms, surgical gowns, surgical masks, and surgical drapes.
  • the monitoring device includes a battery 12 that generates 9 volts that is provided to a voltage converter and regulator 14.
  • the battery 12 also preferably provides a logical ground to the voltage converter and regulator 14.
  • the voltage converter and regulator 14 receives the nine volts and generates voltage outputs referred to as AV+, AV-, AG, DV+ and DG.
  • AV+ is +6 Volts DC
  • AV- is -6 Volts DC
  • DV+ is +5 Volts DC.
  • AG is an analog ground
  • DG is a digital ground.
  • AG and DG are connected at a single point through a low impedance inductor L, so as to avoid ground loops.
  • the voltage converter and regulator 14 also generates a battery low voltage alarm signal referred to as BATT_LOW*.
  • the BATT_LOW* signal lights an LED when the voltage drops below a certain value.
  • the BATT_LOW alarm is independant of the other device alarms, which are generated by the microprocessor. Thus, the battery low voltage alarm will function even if the battery voltage is too low to operate the other alarm circuitry.
  • the monitoring device includes a processing system or microcontroller 20.
  • the microcontroller 20 is preferably the MC68HC11 microcontroller produced by Motorola Semiconductor, Inc. although other controllers can be used. For more information on the Motorola MC68HC11, the HCMOS MC68HC11 single chip microcontroller technical data book, published by Motorola, which is hereby incorporated by reference, should be consulted.
  • the microcontroller 20 is powered by voltages DV+ and DV-, as shown.
  • the microcontroller 20 includes a CPU 22, read only memory (ROM) 24, random access memory RAM 26, EEPROM (Electrically Erasable Programmable Read Only Memory) 28, various timers 30, and a block circuit 32 comprising four analog to digital (A/D) converters.
  • the microcontroller 20 also includes a serial port 34 and parallel ports referred to as port B 36, port C 38 and port D 40.
  • the serial port 34 is preferably used to provide information through a serial link to a central computer (not shown) .
  • Each of the various elements comprising the microcontroller 20 are interconnected through a shared bus 21, as shown.
  • Parallel port B 36 is an 8-bit port and outputs eight bits of data, referred to as PB ⁇ 0:7>, to a digital to analog (D/A) converter 42.
  • the D/A converter 42 is powered by voltages AV+ and AV-, as shown.
  • the D/A converter 42 includes a current to voltage converter (not shown) and outputs a voltage proportional to the eight-bit value of data provided by the parallel port B 36.
  • the voltage output from the D/A converter 42 referred to as Vout, can be computed as follows:
  • Vout 4.6 x (PBO + PBl + PB2 + PB3. + PB4 + PB5 + PB6 + PB7) Volts 2 4 8 16 32 64 128 256
  • 4.6 represents the supply voltage to the D/A converter (6 Volts DC) 42 less two diode drops (of
  • the D/A converter 42 outputs a voltage between zero and 4.6 volts.
  • the output of the D/A converter 42 is coupled through a resistor 44 to the inverting input of an operational amplifier (op amp) 46, thus creating a controlled current source that establishes the current applied to the doctor-patient interface (the glove) .
  • This current is proportional to D/A converter 42 output voltage Vout. Since the inverting input of op amp 46 is at virtual ground, the glove current Ig is determined by Ohm's law and is equal to Vout/R 4 .
  • the current that flows through the resistor 44 is designated as Ig.
  • the current Ig is shown in the direction away from the inverting input of the op amp 46 to the D/A converter 42 as the chosen convention.
  • the non-inverting input of the op amp 46 is connected through a resistor 48 to an AG and reduces the offset bias error of op amp 46.
  • Op amp 46 is powered by AV+ and AV-.
  • the inverting input of the op amp 46 is also connected through a resistor 50 to a jack 52, which is connected via a lead to the respective health care worker H using the gloves that are to be tested. As shown, the gloves can be modeled as a resistor in parallel with a capacitor. The resistance across the gloves is designated as Rn.
  • the output of the op amp 46 is connected through a resistor 54 to a jack 56, which is connected via a lead to the patient P being examined.
  • the op amp 46 acts as a current source, providing current through the resistor 54, the patient P via the lead connected to jack 56, through the gloves and to the health care worker H via the lead connected to jack 52 and back up through the resistors 50 and 44
  • the resistors 50 and 54 limit the maximum current applied to the patient/health care worker interface to less than 10 milliamperes, even in the case of a catastrophic circuit failure.
  • the current flowing through the gloves (Ig) is proportional to the voltage Vout output from the D/A converter 42. When Vout is its maximum value of approximately 4.6 volts, the current Ig flowing through the gloves is 9.7 microamperes. When Vout is at its minimum value of approximately 0.06 volts, then the current Ig is 120 nanoamperes.
  • a pair of protective diodes 57 and 58 are connected between the output of the op amp 46 and the resistor 54.
  • the cathode of diode 57 is connected between the op amp 46 and the resistor 54.
  • the anode of diode 57 is connected to AV-.
  • the anode of diode 58 is connected between the op amp 46 and the resistor 54, with the cathode of diode 58 being connected to AG.
  • the diodes 57 and 58 are low leakage clamping diodes that conduct when the output voltage of op amp 46 is greater than 6.7 volts below virtual ground or more than .7 volts above virtual ground, thus protecting both the health care worker H and the device from voltage transients such as those that might be introduced should the health care worker H neglect to disconnect the monitoring device during defibrillation of the patient P.
  • the non-inverting input of a JFET op amp 60 is connected between the protective diodes 57 and 58 and the resistor 54.
  • the non-inverting input of the JFET op amp 60 has an ultra high input impedance that prevents any of the current Ig from leaking. Since the inputs of op amps 46 and 60 have a high input impedance, the current Ig that flows through the gloves is the same current Ig flowing through the resistor 44. Also, since the microcontroller 20 knows the voltage output from the D/A converter 42 and the resistance of the resistor 44, the microcontroller 20 can easily determine the current Ig flowing through the gloves.
  • the JFET op amp 60 is configured as a unity gain buffer as shown.
  • the op amp 60 is powered by voltages AV+ and AV-.
  • the output of the op amp 60 is connected to the inverting input of the op amp 60.
  • a resistor 62 is connected between the output of the op amp 60 and the inverting input of an op amp 64 to establish a source impedence for op amp 64.
  • the op amp 64 is configured as a low gain inverter and is powered by voltages AV+ and AV-.
  • the output of the op amp 64 is connected through a feedback resistor 66 to the inverting input of the op amp 64.
  • the non-inverting input of the op amp 64 is connected through a resistor 68 to analog ground AG, thus reducing offset bias error of op amp 64.
  • the output of the op amp 64 produces a voltage referred to as Vg.
  • Vg is provided to the input of one of the A/D converters in the block circuit 32 in the microcontroller 20.
  • the microcontroller 20 periodically measures Vg to determine the resistance across the gloves being monitored, as follows. The current Ig flowing through the gloves is determined by the value written to port B 36 as was explained above.
  • the manner in which the microcontroller 20 periodically measures the resistance Rn across the gloves and uses the measured values to detect holes in the gloves is controlled by software stored in the ROM 26 and is explained more fully below.
  • Parallel port D 40 outputs three signals referred to as RED*, YEL*, and GRN*.
  • a signal name followed by an asterisk means that the signal is asserted when it has a logic low value.
  • the RED* signal is provided to the cathode of a light emitting diode 70 whose anode is connected through a resistor 71 to DV+.
  • the YEL* signal is connected to the cathode of a LED 72 whose anode is connected through a resistor 73 to DV+.
  • the GRN* is connected to the cathode of a green LED 74 whose anode is connected through a resistor to 75 to DV+.
  • Parallel port D also outputs a signal referred to as ALARM, which is provided through a resistor 76 to a PNP transistor 78.
  • the collector input of the transistor 78 is connected to ground.
  • the emitter is connected to an input of a piezo electric transducer 80.
  • the other input to the speaker 80 is connected to +9 volts.
  • the ALARM signal is also preferably provided to a vibrating alarm circuit 81 as shown.
  • the vibrating alarm 81 is connected to +9 volts and ground.
  • the BATT LOW* signal output from the voltage converter and regulator 14 is connected to the input of port C 38.
  • the cathode of an LED 69 is also connected to the BATT_LOW* signal.
  • the anode of LED 69 is connected to DV+.
  • FIG. 2A-D a flowchart diagram illustrating operation of software that controls operation of the monitoring device is shown.
  • the flowchart is shown in four portions for clarity, with interconnections between the four figures designated by reference to the circled letters A through E.
  • the software begins operation in step 100 when the monitoring device is powered on. At power on reset, the RED*, YEL*, and GRN* signals are negated high, and thus the corresponding LEDs 70, 72, and 74 are off. Also, the ALARM signal is negated low, and thus the alarms 80 and 81 are turned off.
  • step 102 the microcontroller 20 initializes various variables that are used in the software.
  • Parallel port B 36 is initially provided with value 0, thus providing the minimum voltage output from the D/A converter 42.
  • the actual current Ig flowing through the resistor 44 is 120 nanoamps.
  • IgMAX which represents the maximum current value of Ig
  • IgMIN is set to one, which corresponds to the minimum current value of 120 nanoamps.
  • t is set equal to zero.
  • Vg_HIGH_THRESHOLD are set equal to 2.5 volts and 4.375 volts, respectively.
  • the microcontroller 20 maintains the voltage Vg between the ranges of 2.5 volts and 4.375 volts for optimum reading of the resistance Rn across the gloves.
  • Resistance variables referred to as Rg and RgLast are the outputs of a 2-step software filtering process that consists of a 5- point non-linear median filter, followed by a 2-stage linear averaging filter, both applied to successive values of Rn as indicated.
  • the resistance Rg, and the first and second derivatives of Rg are the values used by the controller 20 in determining whether a hole has formed in the gloves, as is explained below.
  • a variable referred to as RgMIN represents the minimum observed value for the filtered resistance Rg.
  • RgMIN is set to the highest possible value of 2 16 -1 at initialization.
  • a variable referred to as dRg stores the first derivative of Rg, and a variable referred to as d 2 Rg stores the second derivative of Rg.
  • a variable referred to as RgLAST which stores the last computed value of Rg, is set equal to 2 16 -1, or 65,535, the highest value possible upon initialization.
  • a variable referred to as dRgLAST stores the last value of the variable dRg that was monitored by the microcontroller 20 and is also set to 2 16 -1.
  • RgAVG stores the average value of Rg since the last "heartbeat" of the device, which is preferably about eight seconds.
  • the "heartbeat" of the device refers to the fact that the green LED 74 and the transducer 80 are preferably turned on and off every eight seconds to symbolize a heartbeat for the device, i.e., to indicate that the device is operating properly.
  • RgAVG is preferably initialized to 2 16 -1.
  • a variable referred to as ARM_PT stores a resistance value against which the resistance Rg is compared.
  • the variable ARM_PT is preferably set to a value dependent upon perceived risk and is used to determine whether the monitoring devices should consider arming potential events.
  • a boolean variable referred to as ARMED indicates when the device is armed, which occurs when the resistance Rg has fallen below ARM_PT and either the first or second derivatives of the resistance Rg indicate that a puncture or hole condition is likely to have occurred. During initialization, the ARMED variable is set equal to false.
  • a variable referred to as HOLE_PT is set to a resistance indicative of a hole or puncture in the gloves, preferably set to a value dependent upon perceived risk.
  • HYD_PT is set to a resistance at which the glove wearer is warned that the level below which the monitoring device may not be able to reliably detect holes will be reached in the near future. This level is set depending upon perceived risk. This warning is referred to as the END-OF-USE WARNING.
  • ARMWAIT stores the length of time during which the monitoring device may be armed without detecting a hole.
  • variable ARMWAIT is preferably set to 5 seconds.
  • Variables referred to as dRg_PCT and d 2 Rg_PCT represent the percentage change of the value Rg_MIN that must occur in either the first or second derivatives of Rg, respectively, before the device can arm itself, as is explained below.
  • step 104 the controller 20 determines the configuration values stored in the EEPROM 28 by the operator.
  • two bits are used to store a possibility of four different protection configurations (0,1,2, and 3) .
  • a standard level of protection is programmed into the microcontroller 20.
  • the variables H0LE_PT, ARM_PT, HYD_PT, dRg_PCT, and d 2 Rg_PCT are set to levels appropriate to routine use. These levels may be tailored to the electrical characteristics of a particular glove, or family of gloves, or may be set at values appropriate for all gloves.
  • H0LE_PT 1.2M
  • HYD_PT 3.0M
  • dRg_PCT 50%
  • d 2 Rg_PCT 50%
  • the protection level is set to the value 2
  • the settings of these values at level 2 of protection are, as presently known, ARM_PT: 2.6M, H0LE_PT: 2.4 , HYD_PT: 4.0M, dRg_PCT: 50%, and dRg 2 _PCT: 50%.
  • the protection level is set to a value of 3, the highest protection level, then the settings of these values at level 3 of protection are, as presently known, ARM_PT: 5.0M, H0LE_PT: 4.8M, HYD_PT: 6.0M, dRg_PCT: 50% and d 2 Rg_PCT: 50%.
  • the operation of the percentage values dRg_PCT and d 2 Rg_PCT is explained further below. It is noted that other variables such as Vg_LOW_THRESHOLD and Vg_HIGH_THRESHOLD, among others, can be modified according to the protection level configuration set out above. It is also noted that other types of risk configurations can be chosen.
  • Vg_LOW_THRESHOLD and Vg_HIGH_THRESHOLD among others.
  • the monitoring device adjusts various variables to account for various tolerances in the circuitry.
  • each glove monitoring device is tested to account for the various tolerances in the various parts comprising the device.
  • a known resistance is placed across the two jacks 56 and 52 and the voltage Vg is measured.
  • Various data are stored in the EEPROM 24 of the microcontroller 20 to indicate the amount by which the measured Vg differs from the expected value. These values are used in step 106 in order to adjust the above variables to account for the tolerances of the various components forming the device. In step 106, this data is used to alter the configuration values appropriately, and then these values are stored in the RAM 26.
  • step 108 a power-on indication is given by the microcontroller 20 beeping the transducer 80 and illuminating all of the LED's 70, 72 and 74.
  • step 110 the microcontroller 20 performs various system diagnostic checks of the various subsystems, and turns the green LED 74 and the transducer 80 on and off if the system checks OK.
  • the green LED 74 and the transducer 80 are turned on and off every eight seconds to symbolize a heartbeat for the device, i.e., to indicate that the device is operating properly and has passed all self-tests.
  • step 112 the glove monitoring device computes RgAVG, which is the average value for Rg for the last 8 seconds.
  • step 114 the controller 20 determines if the variable ARMED is true. If the device is ARMED in step 114, then the time variable t is incremented by 1 in step 116, and the controller 20 advances to step 118 (Fig. 2B). If the device is not ARMED in step 114, then the device advances to step 118.
  • step 118 the controller 20 determines if the device has been ARMED for a period greater than ARMWAIT, which is preferably 5 seconds. If so, the device unarms itself in step 120 and then advances to step 122. If the device has not been ARMED for greater than ARMWAIT, then the device advances to step 122.
  • step 122 the controller 20 measures the voltage Vg received from the A/D converter in the logic block 32. In the preferred embodiment, the controller 20 takes four measurements of Vg and compares these four values. If these values differ by no more than a predetermined amount, then the four values are averaged to determine Vg for that sampling. If any pair of values of these differ by more than the preset amount, then four new values are obtained and this process is repeated. The controller 20 advances to step 124 when a new Vg value is successfully obtained.
  • Steps 124 through 138 comprise an autorange function wherein the controller 20, having measured the voltage Vg of the gloves, adjusts the current Ig provided to the gloves in order to retain full accuracy over the range of resistances encountered. Thus, as the resistance drops due to hydration of the gloves, the current provided to the gloves is increased to maintain the voltage Vg in the desired range.
  • the controller 20 determines if the voltage Vg is less than the value Vg_LOW_THRESHOLD. If the voltage Vg is determined to be less than Vg_LOW_THRESHOLD then, in step 126, the microcontroller 20 determines if the current Ig is equal to IgMIN, i.e. if value one has been written to parallel port B.
  • the current Ig is at its minimum value of 120 nanoamps. If Ig equals IgMIN in step 126, then in step 128 Ig remains at 1 and the flowchart then returns to step 110. If Ig does not equal IgMIN in step 126, then in step 128 the controller 20 determines if Ig is equal to IgMAX, which in this instance is 255, corresponding to 9.7 microamps. If Ig equals IgMAX in step 130, then the controller 120 returns to step 110.
  • the current Ig cannot be increased any further to increase the voltage Vg. In practice this condition would rarely occur because in this instance the resistance Rg would be so low that an END-OF-USE WARNING would have already sounded, as is discussed below. If Ig is not equal to
  • IgMAX in step 130 then Ig is incremented in step 132 by the controller 20 incrementing the value written to parallel port B.
  • the controller 20 then returns to step 110. It is noted that at power-up of the system, Ig will have been set to IgMIN and thus Ig will initially be set to 1 in step 128. Thereafter the software will loop several times until Ig is incremented to such an extent that the voltage Vg is greater than Vg_LOW_THRESHOLD.
  • step 134 the controller 20 determines if Vg is greater than Vg_HIGH_THRESHOLD. If Vg is not greater than Vg_HIGH_THRESHOLD in step 134, then the controller advances to step 140 (Fig. 2C) . If Vg is greater than Vg_HIGH_THRESHOLD in step 134, then in step 136 the controller determines if Ig is equal to IgMIN.
  • step 136 If Ig equals IgMIN in step 136, then the resistance Rg is at a very high value. In this instance, the controller 20 returns to step 110 and repeats the process. It can be assumed that Rg will eventually decrease due to hydration of the gloves so that eventually Vg will fall below Vg_HIGH_THRESHOLD. If Ig is not equal to IgMIN in step 136, then in step 138 Ig is decremented by the controller 20 writing a value one less than the current value to port B 36. During the remainder of the monitoring period, the autorange function in steps 124-138 maintains the voltage Vg between Vg_LOW_THRESHOLD and Vg_HIGH_THRESHOLD.
  • the controller 20 can read Vg more accurately, and for a longer period of time, thus increasing the length of time that the gloves can be reliably monitored. Also, the autorange function accounts for different types of gloves having varying resistances by ensuring that, regardless of the resistance of the gloves, the voltage across the gloves remains in a readable range.
  • step 140 the controller 20 computes a value for Rn, which is simply the raw resistance of the gloves.
  • step 144 the controller 20 smooths the value Rn with the previous 4 values using a 5-point non-linear median filter. In other words, the values Rn, Rn-1, Rn-2, Rn-3, and Rn-4 are sorted, and the median value is selected to form a new value, this value being designated as Rn s .
  • an averaging linear filter is used to calculate Rg and RgLast.
  • Rg is set equal to the average of (Rn ⁇ , Rnj.- ! , Rn ⁇ - 2 , and Rn s . 3 ) , i.e., the average of the last four smoothed values of Rn.
  • RgLast is set to the average of ( n s _ 4 , Rn s _ 5 , Rn s _ 6 , and Rn s _ 7 ) , i.e., the average of the four smoothed values that immediately preceded the four values used to compute Rg.
  • step 148 the controller 20 determines whether the monitoring device should be ARMED. This determination is based on whether the resistance Rg is less than the variable ARM_PT and either the first derivative dRg is greater than RgMIN x dRg_PCT or the second derivative d 2 Rg is greater than the value RgMIN x d 2 Rg_PCT.
  • step 150 the variable ARMED is set equal to TRUE, and the controller 20 advances to step 152. If the values for Rg, dRg, and d 2 Rg are such that the device should not be ARMED in step 148, then the controller 20 advances to step 152. In step 152, the controller 20 determines if the variable ARMED is true. If the variable ARMED is true in step 152, then in step 154 the controller 20 determines if the resistance Rg is less than the value H0LE_PT.
  • step 156 the controller 20 determines if the device has been armed for a period of time greater than ARMWAIT. If the device has not been armed for a period greater than ARMWAIT in step 156, then in step 158 (Fig. 2D) the END-OF-USE is given. Here the transducer 80 is sounded and the red LED 70 is flashed. The controller 20 then progresses to step 160 where the value RgMIN is reset to zero, and the controller 20 then advances to step 166.
  • the END-OF-USE is sounded in step 158 when the device is armed and Rg is less than H0LE_PT.
  • the END-OF-USE ALARM can be sounded based on other criteria, such as when the device is armed and either dRg or d 2 Rg indicate that a hole has occurred.
  • the END-OF-USE ALARM can be sounded based solely on a certain amount of change in d 2 Rg, or dRg.
  • step 162 If the variable ARMED is not true in step 152 (Fig. 2C) , then the controller 20 advances to step 162. Also, if the variable ARMED is true in step 152, but the resistance Rg is not less than H0LE_PT in step 154, then the controller 20 advances to step 162. If the variable t is greater than or equal to ARMWAIT in step 156, meaning that the device has been armed for greater than ARMWAIT, then in step 157 the controller 20 unarms itself and advances to step 162. In step 162, the controller 20 determines if the resistance RgAVG is less than HYD_PT.
  • the controller 20 is checking to see whether the average resistance RgAVG has dropped to a point below which the glove monitoring device may no longer reasonably detect holes or punctures in the gloves. If the resistance RgAVG is less than the variable HYD PT in step 162, then in step 164 a hydration condition has occurred, and the END-OF-USE WARNING is given.
  • the END- OF-USE WARNING preferably includes lighting the yellow LED 72 and sounds a unique signal on the transducer 80.
  • the controller 20 then advances to step 166 (Fig. 2D) . If RgAVG is not less than HYD_PT in step 162, then the controller 20 advances to step 166.
  • step 166 the controller 20 updates the variable dRgLAST to new value.
  • the variable dRgLAST is set equal to dRg.
  • the controller 20 then advances to step 168 where it determines if the resistance Rg is less than RgMIN. If Rg is less than RgMIN in step 168, then in step 170 RgMIN is set equal to Rg. The controller 20 then returns to step 110. If Rg is not less than RgMIN in step 168, then the controller 20 returns to step 110.
  • Rg is only altered if the new value for Rg has dropped below the previous value of RgMIN. This compensates for the problem where the surgeon withdraws his hands from the patient and thus the resistivity increases due to the surgeon's hands being away from the patient. In this instance, RgMIN will record the lowest value of Rg before the surgeon pulled his hands away from the patient.
  • the variable RgMIN is used in determining whether the monitoring device should ARM in step 148 based on percentage changes in RgMIN.
  • variable RgMIN guarantees that when the surgeon places his hands back onto the patient, and the resistance drops dramatically because of this, the device will not ARM in step 148 because the first and second derivatives will be compared with a percentage change in the prior lowest resistance, RgMIN, not merely on the amount of change that occurred in the resistance.
  • the controller 20 continually progresses through steps 110 to 170, monitoring the resistance, as well as the first and second derivatives of resistance, across the gloves and using these values to determine whether a hole has occurred in the gloves.
  • the autorange function in steps 124 to 138 maintains the measured voltage Vg in a prescribed range for a greater period of time, thus allowing the monitoring device to operate for a greater period of time.
  • the use of the first and second derivatives allows for a more accurate determination of when adulterations or near-adulterations occur.
  • the monitoring device alerts the health care worker when the resistance across the gloves has dropped to a value at which the device can no longer reliably monitor, thus providing added safety.
  • FIGURE 3 GRAPHS a diagram of various graphs illustrating the resistance across gloves versus time and first and second derivatives of the resistance versus time during hydration and hole conditions.
  • Figure 3B it is possible to detect a hole or adulteration by examining the resistance of the gloves versus time. However, looking solely at the resistance of the gloves, a hole could be easily confused with hydration of the gloves.
  • the first derivative of resistance versus time provides a much clearer indication of whether an adulteration has formed in a glove than does merely the resistance itself, as shown in Figure 3D. However, it can be more easily determined as to whether an adulteration has occurred by examining the second derivative of the resistance across the gloves versus time.
  • the glove monitoring device could be miniaturized down to a single integrated circuit, or to a size between the current packaging and a single circuit. If the device were to be fully miniaturized, the device and glove-wearer EKG patch could potentially be integrated, thus allowing the device to be marketed as a disposable.
  • the embodiments having at least certain of the features disclosed extends the functionality of the glove monitoring device to potentially allow gloves from most sources to be tested for periods of time longer than that associated with existing regloving intervals. It is further noted that the monitoring device may also be used to detect adulterations and near adulterations in other articles which act as barriers, such as condoms, surgical gowns, masks and various surgical drapes where the possibility of transmission of communicable diseases is possible.
  • the glove monitoring device generates pulses of current, either AC or pulsating DC, in order to facilitate more accurate monitoring of the electrical properties of the gloves.
  • This allows the glove's electrical characteristics including frequency dependent characteristics, to be fully characterized, thus providing an even greater level of testing accuracy.
  • the operating principle of this alternate embodiment is as follows: As a glove hydrates, its DC resistance decreases, but its capacitance increases. This is due both to the increase in the dielectric constant caused by the absorbed water, and to an increase in dielectric thickness due to swelling. Since capacitive reactance (Xc) is inversely proportional to both frequency and capacitance
  • the alternate embodiment preferably employs the same apparatus as that shown in Figure 1 but uses modified controlling software.
  • the alternate embodiment also includes a computer-controlled adaptive algorithm similar to Figures 2A-D of the preferred embodiment.
  • Figure 4B includes an additional step, step 121, prior to step 122.
  • step 121 the controller 20 generates a waveform by continually changing the value written to parallel port B 36 as the software loops through the flowchart.
  • the software can be designed to generate an AC signal, a pulsating DC signal, a square wave, or a variety of other waveforms. This waveform enables the second embodiment device to monitor the resistance and capacitive effects of the gloves.
  • Figures 2A-D is that in the embodiment of Figures 4A-D the device calculates the impedance Zn according to the formula:
  • Zn Vg(t) ohms ig(t) instead of merely the resistance Rn. It is noted that since Ig is a time varying current in this alternate embodiment, both Ig and Vg are now time dependent, as shown above. Accordingly, the value Zn will include both a resistance component and a capacitive reactance component. In Figures 4A-D the variables Rn and Rg, as well as the other variables based on Rn and Rg, are changed to Zn and Zg, respectively.
  • this alternate embodiment operates by measuring the impedance (as opposed to merely the resistance) , the rate of change of that impedance, and the second derivative of impedance, across a circuit comprised of the patient, the health care worker, and the gloves worn by the health care worker. These impedance measurements take into account the resistive and capacitive reactance contributions to the glove impedance.
  • this alternate embodiment more accurately models the glove as an electrical device in order to improve the accuracy and resolution of the measurements being made, and is designed to better distinguish between changes in the electrical properties of the glove caused by glove puncture and changes caused by glove hydration.

Landscapes

  • Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Surgery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Medical Informatics (AREA)
  • Public Health (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Engineering & Computer Science (AREA)
  • Molecular Biology (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Veterinary Medicine (AREA)
  • Measuring And Recording Apparatus For Diagnosis (AREA)
  • Examining Or Testing Airtightness (AREA)
  • Orthopedics, Nursing, And Contraception (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)

Abstract

Dispositif de surveillance permettant de détecter l'altération d'un article destiné à des applications à risque telles que des gants chirurgicaux portés par un chirurgien et exposés aux liquides biologiques d'un patient. Le dispositif permet de détecter une valeur particulière d'un état électrique, de préférence la résistance ou l'impédance, ainsi que des première et seconde dérivées de l'électrique. Ces valeurs sont surveillées de manière sensiblement continue, et sont lissées et filtrées afin de déterminer la présence d'un trou ou d'une région élimée dans le gant. En outre, le dispositif comprend une fonction d'auto-ajustement qui maintient la tension mesurée dans une plage prescrite, ce qui permet au dispositif de fonctionner à un niveau de précision supérieur et pendant une durée plus longue qu'un dispositif ne possédant pas cette caractérisique. Le dispositif avertit également le personnel de santé lorsque les caractéristiques électriques des gants se sont détériorées au point où le dispositif ne peut plus détecter de manière fiable des trous dans les gants.
PCT/US1993/001853 1992-03-04 1993-03-03 Dispositif de surveillance ameliore pour elements de protection chirurgicaux Ceased WO1993017627A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AU37840/93A AU3784093A (en) 1992-03-04 1993-03-03 Enhanced monitoring device for surgical barriers
BR9306029A BR9306029A (pt) 1992-03-04 1993-03-03 Aparelho de monitoração aperfeiçoado para barreiras cirúrgicas
JP5515828A JPH08504265A (ja) 1992-03-04 1993-03-03 外科用手袋、その他の防護具に対する強化された監視装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US84653992A 1992-03-04 1992-03-04
US846,539 1992-03-04

Publications (1)

Publication Number Publication Date
WO1993017627A1 true WO1993017627A1 (fr) 1993-09-16

Family

ID=25298221

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1993/001853 Ceased WO1993017627A1 (fr) 1992-03-04 1993-03-03 Dispositif de surveillance ameliore pour elements de protection chirurgicaux

Country Status (4)

Country Link
JP (1) JPH08504265A (fr)
BR (1) BR9306029A (fr)
CA (1) CA2117639A1 (fr)
WO (1) WO1993017627A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1285418A4 (fr) * 2000-04-12 2004-04-28 Ansell Healthcare Prod Inc Gant communiquant equipe de microcircuits en inclusion
CN106859771A (zh) * 2017-02-28 2017-06-20 锦州医科大学 一种具有防破损预警功能的手术手套

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU712082A1 (ru) * 1978-07-31 1980-01-30 Куйбышевский Медицинский Институт Им. Д.И.Ульянова Устройство дл контрол целости хирургических перчаток
US4956635A (en) * 1989-04-14 1990-09-11 Langdon Robert S Method and apparatus for testing personal barriers
US5036309A (en) * 1990-06-14 1991-07-30 Dennison Jr Everett G Portable system and method for continuously monitoring protective clothing for detecting and signaling the occurrence of a breach therein
US5114425A (en) * 1990-05-25 1992-05-19 Novatec Medical Products, Inc. Method and apparatus for detecting actual or likely adulteration of critical use gloves
US5157379A (en) * 1990-06-14 1992-10-20 Everett Dennison Method for monitoring a protective garment

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU712082A1 (ru) * 1978-07-31 1980-01-30 Куйбышевский Медицинский Институт Им. Д.И.Ульянова Устройство дл контрол целости хирургических перчаток
US4956635A (en) * 1989-04-14 1990-09-11 Langdon Robert S Method and apparatus for testing personal barriers
US5114425A (en) * 1990-05-25 1992-05-19 Novatec Medical Products, Inc. Method and apparatus for detecting actual or likely adulteration of critical use gloves
US5036309A (en) * 1990-06-14 1991-07-30 Dennison Jr Everett G Portable system and method for continuously monitoring protective clothing for detecting and signaling the occurrence of a breach therein
US5157379A (en) * 1990-06-14 1992-10-20 Everett Dennison Method for monitoring a protective garment

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1285418A4 (fr) * 2000-04-12 2004-04-28 Ansell Healthcare Prod Inc Gant communiquant equipe de microcircuits en inclusion
CN106859771A (zh) * 2017-02-28 2017-06-20 锦州医科大学 一种具有防破损预警功能的手术手套

Also Published As

Publication number Publication date
CA2117639A1 (fr) 1993-09-16
BR9306029A (pt) 1997-11-18
JPH08504265A (ja) 1996-05-07

Similar Documents

Publication Publication Date Title
US5389097A (en) Enhanced monitoring device for surgical gloves and other barriers
CA1200286A (fr) Systeme de controle a electrode de retour adaptatif
EP2223666B1 (fr) Outils pour la détection du chauffage au- dessous d'une électrode neutre
US5383874A (en) Systems for identifying catheters and monitoring their use
US6007532A (en) Method and apparatus for detecting loss of contact of biomedical electrodes with patient skin
US3584618A (en) A system and method for monitoring a progressive sequence of physiological conditions
EP0909551B1 (fr) Selection de valeurs limites pour les systèmes de surveillance de patient
US4956635A (en) Method and apparatus for testing personal barriers
US12303301B2 (en) Intraoperative neural monitoring system and method
BR112020005971B1 (pt) Luva de detecção de tensão
CN102048543A (zh) 生物信息监测装置以及警报控制方法
CN111249572B (zh) 生命体征监测系统
JP2005521456A (ja) 突然心停止モニターシステム
US5114425A (en) Method and apparatus for detecting actual or likely adulteration of critical use gloves
WO1993017627A1 (fr) Dispositif de surveillance ameliore pour elements de protection chirurgicaux
AU3784093A (en) Enhanced monitoring device for surgical barriers
US5658277A (en) Apparatus for electrical connection of glove monitor to patient
US5251622A (en) Responsive pacemaker with time domain reflectometer and method of use
JP7658523B2 (ja) 電極品質の試験
Simons et al. The evaluation of an auditory alarm for a new medical device
CN112914745B (zh) 自适应动态中性电极接触质量检测方法
Nanditha et al. Glove Rupture Detection System using skin impedance.
CN121057555A (zh) 用于测量医疗电极上的温度的测量装置
CN113679944A (zh) 检测双向半导体器件中的不对称性
WO1993020890A1 (fr) Stimulateur cardiaque a reflectometre a dimension temporelle

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AT AU BB BG BR CA CH CZ DE DK ES FI GB HU JP KP KR LK LU MG MN MW NL NO PL RO RU SD SE SK

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN ML MR SN TD TG

WWE Wipo information: entry into national phase

Ref document number: 2117639

Country of ref document: CA

WWE Wipo information: entry into national phase

Ref document number: 1993907131

Country of ref document: EP

REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

WWW Wipo information: withdrawn in national office

Ref document number: 1993907131

Country of ref document: EP

122 Ep: pct application non-entry in european phase