Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M41/00—Means for regulation, monitoring, measurement or control, e.g. flow regulation
  • C12M41/12—Means for regulation, monitoring, measurement or control, e.g. flow regulation of temperature
  • C12M41/14—Incubators; Climatic chambers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
  • B01L7/00—Heating or cooling apparatus; Heat insulating devices
  • B01L7/02—Water baths; Sand baths; Air baths
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M23/00—Constructional details, e.g. recesses, hinges
  • C12M23/48—Holding appliances; Racks; Supports
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M41/00—Means for regulation, monitoring, measurement or control, e.g. flow regulation
  • C12M41/48—Automatic or computerized control
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
  • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
  • G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
  • G01N21/783—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour for analysing gases
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
  • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
  • G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
  • G01N21/80—Indicating pH value
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
  • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
  • G01N2021/7769—Measurement method of reaction-produced change in sensor
  • G01N2021/7786—Fluorescence
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
  • G01N35/02—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor using a plurality of sample containers moved by a conveyor system past one or more treatment or analysis stations
  • G01N35/04—Details of the conveyor system
  • G01N2035/0496—Other details
  • G01N2035/0498—Drawers used as storage or dispensing means for vessels or cuvettes

Definitions

• This invention relates generally to analytical apparatus for detecting the presence of bacteria in human tissue, and is particularly directed to automated apparatus for culturing and detecting viable bacteria in human blood specimens.
• Bacteremia the prolonged presence of one or more viable bacteria in the blood ⁇ is a serious and life- threatening infection.
• the most common symptom of bacteremia is a fever of unknown origin. Accordingly, hospitals routinely perform a large number of tests to determine whether patients exhibiting this symptom have bacteremia.
• the only way a definitive diagnosis can be made is by isolating bacteria in the blood by means of a so-called "blood culture.” Because bacteremia is life-threatening, positive specimens must be detected as quickly as possible so that the patient can be treated with the correct antibiotics.
• the conventional manual method involves inoculating bottles containing a growth medium with blood specimens.
• the growth medium is formulated to provide nutrients for bacterial growth.
• the bottles are inspected daily for obvious signs of bacterial growth. Samples from bottles suspected to be positive are then further cultured -to obtain isolated bacterial colonies-vhich can then be identified.
• This method is very labor-intensive and costly, since daily inspections and ⁇ ubculturing of suspect bottles are required.
• Various attempts have been made to improve the conventional manual method. For example, culture bottles have been made with added attachments containing solid media. The user inverts the bottle each day, thereby inoculating the solid media and enabling growth of isolated bacterial colonies, which can then be identified.
• a third method is to concentrate organisms in the specimen by centrifugation and then culture the concentrated bacteria on solid media. Despite such improvements, these methods still suffer from the drawback of being highly labor- intensive. Attempts to automate the process of culturing blood specimens have also been made. Most automated processes rely on the fact that bacteria cultured in a medium including a carbon source, such as glucose, break down this carbon source to form CO2 as part of normal growth and metabolism. Early efforts at automation used culture bottles containing radioisotope-labelled media. Blood specimens are inoculated into the bottle.
• Bacteria if present in the specimen, metabolize the carbon-containing compounds in the media and give of radioactive-labelled CO2 as a waste product.
• Gas in the headspace of the bottle is sampled by puncturing the seal at the top of the bottle with a needle and removing a portion of the gas.
• the radioactive CO2 can then be detected by conventional radiometry.
• Application No. 85302261.4 describes a system in which radioisotope labelling has been replaced with direct detection of non-radioactive C0 2 in the headspace gas by means of infrared spectroscopy. While this alleviated the problems associated with radiometric detection, the shortcomings of invasive sampling remain. In addition, the use of infrared spectroscopy requires that culture bottles be made of special materials.
• EPO Application No. 83108468.8 discloses a system which detects CO2 levels in the headspace gas by taking infrared readings directly through the culture bottle, i.e.-, noninvasively.
• the instrument disclosed is equipped with only a single light source and detector. This, in turn, requires that the culture bottles be periodically cycled past the detector for readings, thus increasing the mechanical complexity of the instrument and limiting the number of samples the instrument can rapidly process.
• problems can occur in calibrating the infra-red spectrometer to the many bottles which must be read.
• the bottles are periodically agitated (to increase the diffusion of C0 2 and thereby shorten detection time) while being incubated at approximately 35 ⁇ C.
• a colorimetric sensor (pH indicator) is adhered to the bottom inside surface of each bottle. The sensor turns from green to yellow as the level of C0 2 within the media increases.
• optical units include LEDs to illuminate the sensor, photodetectors, and associated electronics and signal conditioning equipment.
• the instrument periodically "reads” each sensor using reflected light to monitor changes in the transmission of the sensor at a specific wavelength. When a level of CO2 consistent with microbial growth is reached, the instrument alerts the user of a positive blood culture.
• the detection system is based on changes in the light transmission of the sensor, the light illuminating the sensor is the same wavelength as the light reflected from the sensor. This makes it possible for light which is not indicative of changes in the sensor (e.g., light reflected from the bottom of the glass or plastic culture bottle, as well as other reflective surfaces) to reach the detector. Because the detection system does not discriminate between light reflected from the sensor and such unwanted
• noise the dynamic range of detection is generally more limited. In addition, it becomes critical to physically isolate the illuminating light source from the detector, placing further design constraints on the configuration of the optical system.
• an automated blood culture instrument which is capable of incubating blood specimens under the appropriate conditions, but which has a compact design, thereby reducing the laboratory floor space it occupies and making it more convenient for use by laboratory medical technicians.
• an instrument which uses non-invasive sampling and non-radiometric detection, but which has a highly accurate and sensitive detection system, which does not rely upon measuring changes in light transmission of monochromatic light.
• an instrument for detecting the presence of microorganisms in human tissue including a housing and one or more drawers slidably received in the housing.
• the drawers include means for holding a plurality of specimen-containing vessels.
• the drawer is movable between a first, closed position, in which the vessel holding means is substantially enclosed within the housing, and a second, open position, in which the vessel holding means is located substantially outside of the housing.
• a large number of specimen-containing vessels can be stored inside the instrument for incubation (including warming, agitation, and measurement of bacterial growth) , while still being readily accessible to the operator of the instrument upon opening of the drawer.
• Such an arrangement permits a large number of vessels to be stored while greatly reducing the overall size and "footprint" of the instrument.
• a unique warming system which preferably utilizes forced air convection within the drawer, is used to warm the interior of the drawer to an elevated temperature suitable for encouraging growth of microorganisms while the drawer is closed.
• Another aspect of the present invention is an instrument having a unique optical detection system for detecting the presence of bacterial growth within the specimen.
• This system includes light emission means for emitting excitation light falling within an emission wavelength range.
• the system is configured so that the excitation light impinges upon a specimen- containing vessel held within the instrument and, more particularly, upon a sensor located inside the vessel.
• Light emanating from the sensor (which, preferably, includes a light emitting fluorophore) is detected by a light detection means, which converts the light energy emitted by the sensor into a detectable signal.
• a filter means optically interposed between the light source and the detector. The filter is designed to achieve substantial spectral isolation between the excitation light and the light emanating from the sensor. In this way, substantially all light falling within the emission wavelength range is prevented from reaching the detector, thus rendering the detection means substantially "blind" to light falling within the emission wavelength range. It has been discovered that such an arrangement improves the overall sensitivity of the instrument.
• Yet another aspect of the present invention is an instrument having a unique agitation system for agitating the specimen containing vessels while they are being held within the instrument.
• the agitation system utilizes a mechanical arrangement designed to agitate the vessel holding means in a manner in which its distance of travel from a fixed reference point increases and decreases in a substantially sinusoidal manner. This sinusoidal pattern of motion makes it possible to start and stop the agitation more easily, thus helping to simplify and reduce the cost of the components used to manufacture the instrument.
• Still a further aspect of the present invention is an instrument having a unique means for gripping the specimen-containing vessels within the instrument.
• This gripping means is designed to removably and repeatably hold the vessel at a predefined, substantially fixed depth within a vessel receiving aperture. This arrangement helps to ensure that the vessel is correctly and consistently positioned relative to the optical detection unit.
• the gripping means is also adapted to provide audible or tactile feedback to an operator when the vessel is properly inserted into the aperture. Such feedback helps to ensure that the operator inserts the vessel into the aperture correctly.
• FIG. 1 is a perspective view of an automated blood culture apparatus made in accordance with the present invention
• FIG. 2 is a side view of the apparatus, showing one of the specimen-holding drawers in its open position;
• FIG. 3 is a view similar to that of FIG. 2 in somewhat schematic form, with portions of the specimen- holding assembly removed to show the system for heating and circulating air within the specimen-holding drawers;
• FIG. 4 is a side view of the specimen-agitating assembly used in one embodiment of the present invention, showing the specimen-containing racks in their lowermost agitation position;
• FIG. 5 is a view similar to that of FIG. 4, showing the specimen-containing racks in their uppermost agitation position;
• FIG. 6 is a top view of one of the specimen- containing drawers taken along the line 6—6 in FIG. 1;
• FIG. 7 is a front view of one of an individual specimen holder;
• FIG. 8 is a cross-sectional view taken along the lin 7—7 in FIG. 7;
• FIG. 9 is a side view of an alternative bottle- gripping arrangement for retaining culture bottle within the bottle holding racks;
• FIG. 10 is a perspective view of an assembly for moving the specimen-holding drawers between their closed and open positions;
• FIG. 11 is a perspective view of an assembly for agitating the specimen-containing racks
• FIG. 12 is a dwell chart showing the relative position of the specimen-containing racks during several agitation cycles in graphical form;
• FIG. 13 is a graph of intensity as a function of wavelength, showing schematically the optical properties of the excitation light as well as the light emitted by the fluorescent sensor;
• FIG. 14 is a side view of an alternative assembly which may be used to agitate the specimen-containing racks.
• Figs. 1 and 2 show the general arrangement of an instrument 10 made in accordance with the present invention.
• This Specification describes a preferred form of the invention, in which the instrument is used to culture and detect bacteria in human tissue and, in particular, in human blood.
• the instrument is described as being used for detection of microorganisms or bacteria in blood, it will be understood that the instrument may be used to detect microbial growth in any number of tissues, including urine, cerebral-spinal fluid, synovial fluid, and others.
• Fig. 1 illustrates the instrument of the present invention generally.
• Instrument 10 includes a specimen-handling module 12 under the control of a microcomputer 14, which is preprogrammed to follow certain specimen-handling protocols in accordance with input from the user.
• a microcomputer 14 which is preprogrammed to follow certain specimen-handling protocols in accordance with input from the user.
• a detailed description of the general types of software commands and processing steps which could be used to program the microcomputer to perform such protocols is attached as an Appendix hereto.
• each specimen-handling module 12 includes a housing 32 and two slide-out drawers 16, 18, each of which includes a plurality of racks 20, 22, 24, 26, 28, 30, which hold the specimen- containing vessels or bottles for processing.
• drawer 16 is shown in its open position, while drawer 18 is shown in its closed position.
• each of the slide-out drawers 16, 18 is equipped with a heating system (see Fig. 3) designed to warm the drawers to the appropriate temperature for bacterial growth and maintain them substantially at that temperature.
• Each of the drawers 16, 18 is also equipped with a mechanical agitation system (see Figs. 4 and 5) for periodically agitating the bottles. Such agitation is known to shorten the time to detection by causing C0 2 generated by bacteria within the bottle to diffuse more rapidly to the fluorescent sensor, which is preferably affixed to the bottom inside of the bottle.
• the drawers 16, 18 are also equipped with an optical detection system, including a plurality of optical units (see Figs. 7 and 8) which monitor CO2 production by optically interrogating the fluorescent sensors on each of the culture bottles. Optical readings for each bottle are transferred via a data link (not shown) to the microcomputer 14, where it is stored for later retrieval and use.
• a blood culture instrument module includes at least one, and preferably two or more, slide-out drawers 16, 18 slidably received in housing 32 for holding the blood specimen-containing vessels or bottles during processing.
• the instrument has sufficient bottle-holding capacity for hospital laboratory use, while maintaining a compact size and a small "footprint" desirable for most users. This is because the bottles can be held within the instrument for most processing steps, while still keeping them readily available and within easy reach of the laboratory technician upon opening the drawer.
• the compact size of the instrument made in accordance with the present invention is an important advantage in most settings, particularly hospitals, since laboratory space is generally limited due to the large number of instruments and pieces of equipment housed within a typical microbiology laboratory.
• each drawer includes an information panel/user interface for displaying information relating to the specimens held within that drawer and for enabling the user to control certain functions pertaining to that drawer.
• the information panel for drawer 16 is designated by the reference numeral 17.
• Information which may be displayed on the information panel by, for example, LED or LCD displays, include the temperature within the drawer, the number of specimen bottles which have been read as "positive,” and the number of available positions for additional specimen bottles.
• Functions which may be controlled by the user may include opening and closing the drawer, as well as disabling an alarm designed to signal, for example, a positive reading within the drawer.
• the system of the present invention is preferably designed so that multiple specimen-handling modules may be interfaced with a single microcomputer. In this way, the specimen-holding capacity of the system may be substantially increased, as desired.
• the modules are also preferably designed so that they may be stacked one atop another if desired, to minimize the amount of floor space the system occupies.
• the drawer 16 is slidably received within housing 32.
• a pair of integral slide extensions 34a, 34b are rigidly affixed to the drawer 16 by means of screws, bolts or the like at a position adjacent the top of drawer.
• the slide extensions are slidably received within tracks 36a 36b.
• Tracks 36a, 36b are themselves slidably received within receiving guides (not shown) which are rigidly mounted to the inside of housing 32.
• Conventional ball bearing assemblies (not shown) permit the slide extensions 34a, 34b to slide freely within tracks 36a, 36b, and the tracks 36a, 36b to slide freely within the receiving guides.
• the slide extensions 34a, 34b, tracks, 36a, 36b, and receiving guides are commercially available in the form of a three-section ball bearing slide which permits the drawer 16 to slide in and out of housing 32. Success has been had with a three-section ball bearing slide Model No. ESBB manufactured by Barnes Engineering Company of Anaheim, California.
• the slides are made of hardened steel which has been electro ⁇ plated such that they adequately support the drawers 16, 18 while maintaining their corrosion resistance under the temperature conditions prevailing within the drawers.
• Fig. 10 illustrates the manner in which the bottom of drawer 16 is slidably mounted within the housing.
• a single three-part ball bearing slide positioned to lay flat (i.e., rotated clockwise 90 degrees relative to the slide extensions 34a, 34b of the three-part slides illustrated in Fig. 1) is used to prevent the drawer from "wobbling" from side to side within the housing.
• the slide extension (not shown) , is rigidly attached to the underside of drawer 16 within a longitudinal recess 150 which runs substantially the length of the drawer 16. This extension is received in a track 152, which, in turn, is received within receiving guide 154 mounted 5 to the inside of the drawer housing.
• Figs. 1 and 10 illustrate one method of slidably attaching the drawer to the housing 32 using three-part ball bearing slides, it will be understood that the drawers may be slidably mounted to the housing using any suitable means, such as, by way of example, s conventional slides, tongue and groove configurations, and the like.
• a command from the user which can 5 be input, for example, from microcomputer 14 or from the information display/user interface 17 in Fig. 1.
• motor M under the control of the microcomputer, powers an associated belt drive 156.
• the belt drive 156 rotates a screw drive 158 0 which engages threaded drawer extension 160.
• the drawer extension 160 is rigidly attached adjacent a lower corner of the drawer 16.
• the rotating screw drive moves the drawer under power in or out of the housing, as desired, in 5 the directions of the double-headed arrow.
• Appropriate flags are used to signal the microcomputer to deactivate the motor M once the drawer 16 reaches its open or closed position.
• the drawer 16 also includes means for holding a plurality of specimen- containing vessels.
• This vessel-holding means may take the form of a plurality of racks 20, 22, 24, 26, 28, 30 which are adapted to hold or retain the specimen bottles during processing.
• Each rack has a plurality of bottle-receiving openings 38 which are sized to accommodate specimen bottles.
• an optical unit 46 for taking optical readings of a sensor affixed to the bottom inside of the bottle.
• the bottle receiving openings are illustrated as being circular to accommodate a generally cylindrical specimen bottle, it will be understood that apertures having a variety of shapes (e.g., rectangular, triangular, or polygonal), could also be used in appropriate circumstances.
• the drawer 16 is illustrated with six racks accommodating 10 bottles each, it will be understood that other quantities may also be held within the racks. Indeed, it is preferred that each drawer accommodate as many bottles as possible in order to maximize the capacity of .each module.
• the vessel-holding means When the drawer is in its closed position, the vessel-holding means should be substantially enclosed within, i.e., covered by, the housing. It will be understood that the vessel-holding means need not be completely enclosed within the housing, so long as the vessels are substantially located within the housing, thereby reducing the amount of space the instrument module occupies. Likewise, when the drawer is in its open position, the vessel-holding means should be located substantially outside the housing, i.e., in a position in which the vessels can be readily accessed or removed by the instrument operator.
• the racks may be fastened together to form an integrated assembly, as illustrated in the drawings, or may be fabricated as individual units which can be removably attached within the drawer 16. It may be desirable in certain circumstances for individual racks to be removed so that specimen bottles can be inserted offsite, and then the racks can be reinserted into the instrument at a later time. It will be understood that this can be accomplished in any number of ways, including providing a frame within the drawer to which the racks may be removably attached.
• each bottle holding rack is equipped with an LED (light emitting diode) panel 15, which includes an array of LEDs 19, two of which are associated with each bottle receiving opening 38.
• the LEDs associated with each opening provide the user with information concerning the status of the optical readings for the bottle contained in that opening. For example, a red LED might indicate a bottle testing "positive," while a green LED might indicate a bottle which has as yet tested “negative.”
• the panel 15 may take the form of a printed circuit board which includes the array of LEDs for all of the bottle receiving openings in that rack, as well as associated circuitry for transmitting on/off information and power to the LEDs under the control of the microcomputer. The panel 15 may then be removably mounted to its rack by means of Velcro® fasteners or other similar means.
• Fig. 7 depicts a portion of one of the bottle- holding racks in greater detail.
• gripping means Adjacent each bottle- receiving aperture is gripping means adapted to removably grip the specimen-containing vessel so that it may be repeatably held at a predefined, substantially fixed depth within the aperture. This depth is predefined and substantially fixed to allow the optical unit to interrogate the sensor affixed to the specimen-containing vessel from a well-defined and repeatable position, thereby ensuring more accurate optical readings when a vessel is removed and then reinserted.
• the gripping means may comprise one or more flexible arms positioned adjacent the periphery of the aperture.
• the gripping means may take the form of one or more arms.
• the gripping means includes three outwardly extending fingers 40a, 40b, 40c positioned around the periphery of each cylindrical opening 38 in order to repeatably position and support the bottle within the rack.
• the fingers may be fastened to the base of the rack (shown in Fig. 9) or formed integrally therewith so that they protrude upwardly adjacent the opening.
• the fingers 40a, 40b, 40c are molded integrally with the base of each rack from a suitable thermoplastic resin, such as an acrylonitrile- butadiene-styrene (ABS) resin or an acetal resin (e.g., Delrin®, a registered trademark of E.I. Du Pont de Nemours & Co.).
• ABS acrylonitrile- butadiene-styrene
• acetal resin e.g., Delrin®, a registered trademark of E.I. Du Pont de Nemours & Co.
• the fingers 40a, 40b, 40c are uniformly spaced at approximately 120° intervals around the periphery of the opening.
• Each of the fingers 40a, 40b, 40c includes a recessed portion 41a, 41c (the recessed portion of finger 40b is not visible in Fig. 7) which is shaped to engage an engagement area on the outside surface of a specimen bottle.
• a flanged end 42a, 42b, 42c on each finger is designed to engage the shoulder of culture bottle inserted into the aperture 38.
• the fingers 40a, 40b, 40c are arranged to form an opening which is smaller than the diameter of the culture bottle.
• the fingers 40a, 40b, 40c should also be capable of flexing or deforming outwardly to admit the bottle and, in cooperation with the flanged ends 42a, 42b, 42c, to engage the shoulder of the culture bottle in a "snap-fittable" mechanical arrangement once the bottle has been inserted to the pre-defined depth within the aperture.
• Such an arrangement has several advantages. First, it helps to properly position the bottom of the bottle (and, as a result, the sensor affixed to the bottle) securely and repeatably against the optical unit 46 to ensure accurate and consistent optical readings. Second, such an arrangement preferably gives the instrument operator tactile and/or audible feedback when the bottle is properly seated within the opening, helping to reduce errors in loading and positioning the bottles. In the absence of such tactile feedback, the operator could insert the bottle into the opening to varying degrees, causing inaccuracy and inconsistency in the optical readings.
• the bottle gripping means includes springs 53 formed of a resilient metal, such as spring stainless steel. Again, it is preferred that at least three, and preferably four, springs 53 be provided for each bottle and that they be equally spaced around the opening. However, it will be understood that two or even one .spring could be used.
• the springs 53 are attached to base plate 57 (which, in this embodiment is made from aluminum or another suitable metal) by riveting, welding, or other conventional means.
• Base plate 57 has a plurality of apertures formed therein so that the sensor (not shown) affixed to the inside of the bottle 120 can be optically interrogated by the optical units 46.
• Each spring 53 has a crimp 55 formed in one end for gripping the bottle 120.
• the crimps 55 are shaped to engage a corresponding engagement area taking the form of an indentation or detent 47 in the bottle 120.
• the springs are flexible and resiliently deformable so that when the bottle 120 is inserted into the bottle receiving opening, the springs 53 are resiliently deformed in an outward direction to admit the bottle 120.
• the springs 52 return substantially to their original position and engage the detent 47 in the bottle 120. This is evident to the operator by the tactile and audible feedback provided when the bottle "snap-fits" into tight, mechanical engagement with the springs 53.
• Fig. 9 also illustrates the manner in which the optical units and related circuitry are attached to the base plate 57 of the bottle holding racks.
• a plurality of PEM fasteners 59 are rigidly affixed to the base plate 57 at spaced intervals along its length.
• Each PEM fastener has an annular base 54 and plurality of prongs 56 adjacent its opposite end.
• a plurality of optical units 46 — one for each bottle receiving opening — are attached along the length of a printed circuit board (PCB) 41.
• the PCB 41 is equipped with the necessary circuitry for providing power to the optical units and for transmitting the optical readings (which, as explained in greater detail below, are converted into a voltage by the optical unit) to the microcomputer for storage and later use.
• the PCB 41 also has a plurality of holes formed along its length.
• the prongs 56 on the PEM fasteners 59 are inserted into the holes in the PCB 41 until the PCB engages the annular bases 54.
• the prongs 56 deform inwardly so that they can pass through the apertures in the PCB 41 and then spring back to their original position so that they retain the PCB 41 in engagement with the annular bases 54. In this way, the PCBs 41 are easily assembled to the bottle holding racks, and can easily be removed for repair or replacement.
• each drawer is preferably equipped with a bar-code reader 162 centrally positioned within a V-shaped channel 164, which extends longitudinally across the drawer 16.
• the channel 164 is sized to accommodate specimen bottles which are to be inserted into one of the bottle receiving openings 38.
• a bar-code label is placed on the side of each specimen bottle to identify the patient from whom the specimen was taken. It will be understood that many hospitals now employ systems in which detailed information about a patient is associated with a unique bar-code for that patient. Labels containing that bar-code are then used to track and identify treatments and procedures pertaining to that patient.
• the instrument of the present invention should be capable of interfacing with the hospital bar-code system, if available.
• bar-code labels could be generated solely for use with the instrument of the present invention to track specimens and identify them as having come from a particular patient.
• the user When the user wishes to insert a specimen bottle into the drawer, he or she places the area of the specimen bottle bearing the bar-code label in the V- shaped channel 164 and draws the bottle across the bar ⁇ code reader 162 to scan the patient information into the microcomputer.
• the system automatically detects where the bottle is placed within the drawer so that the patient information can be associated with the optical readings for that bottle.
• the optical readings and associated patient information are stored for later retrieval and use.
• the interior face of the drawer is equipped with a second user interface/ information panel 166. This user interface enables the user to perform certain additional operations, and provides certain additional information, such as instructions for inserting a new bottle into an available bottle-receiving aperture.
• the present invention includes means operably associated with the slide-out drawers for (1) warming the interior of the drawer to an elevated temperature suitable for encouraging growth of microorganisms, and (2) maintaining the interior of the drawer substantially at or near that elevated temperature, when the drawer is in its closed position.
• such means comprises a forced air convection system which will now be described in detail.
• Fig. 3 illustrates the interior of one of the slide-out drawers 16 with the bottle-holding racks removed.
• Adjacent the interior front end of the drawer 16 is a forward duct 60 positioned vertically within the drawer 16.
• the forward duct 60 is substantially hollow and open at side 61, which faces the interior of the drawer 16.
• Forward duct 60 is attached at its base to base plate 62, which is positioned transversely to the forward duct 60 adjacent the interior bottom of the drawer 16.
• Adjacent the -interior rear end of the drawer 16 is a vertically positioned rear duct 64, which is open at side 63 facing the interior of the drawer 16 and which is also attached to base plate 62.
• the ducts are formed of punched sheet metal, which is then bent and welded, or by other conventional methods of metal forming. It will be understood, however, that the ducts may be formed of other materials, such as molded plastic, and may be formed in a variety of shapes and configurations.
• upper openings 63, 65 of the vertically extending forward and rear ducts 62, 64 are brought into alignment with corresponding openings in upper duct 66, located within the module in the following manner.
• Upper duct 66 forms a passageway which is generally in the shape of an inverted U.
• the vertical segments of this inverted U-shaped passageway are brought into alignment with the upper openings 63, 65 of the forward and rear ducts located within the drawer 16, so that air may circulate from this upper passageway into the forward and rear ducts 60, 62.
• a blower fan 68 Located within the upper duct 66 are a blower fan 68 and a heating coil 70.
• the fan 68 is energized and forces air in the direction of the arrows in Figure 3.
• the air passes over the heating coil 70, where it is warmed.
• the heated air then passes downwardly in the direction of the arrows into the interior of the drawer 16 through the upper opening 65 in the rear duct 64 located within the drawer 16.
• the rear duct 64 is equipped with a plurality of louvres 72, which are sloped in order to direct and channel the heated air over, around, and across the culture bottles held within the racks.
• the openings between the louvres 72 coincide generally with the position of the bottle- holding racks. (A representative bottle, illustrated without its holding rack, is identified by reference numeral 76 in Figure 3.)
• the louvres also increase in size (and, in particular, width) from the top to the bottom of the rear duct 64. Because the air flow decreases at greater distances from the fan 68, this configuration assists in distributing the heated air in a substantially equal manner to each of the bottle holding racks in the drawer. After the heated air circulates within the closed drawer, passing over the bottles and thereby warming the specimens and media contained inside, it passes under the force of fan 68 into the forward duct 60. The air then passes upwardly (in the direction of the leftmost arrows in Figure 3) past a temperature probe 67 which monitors the air temperature.
• Temperature information is conveyed to the microcomputer, which is programmed to energize the fan 68 and heating coil 70 as needed in order to maintain the temperature of the interior of the drawer at about 35-37 ⁇ C and, more preferably, at 35 +2/-1 ⁇ C, in order to encourage bacterial growth within the specimen bottle.
• the instrument may be designed to maintain the internal temperature in other appropriate temperature ranges.
• the preferred temperature for culturing many types of fungi is approximately 31 ⁇ C.
• the instrument should be designed to maintain a temperature which is optimal for the particular type of microorganism to be detected. It will also be understood that some fluctuation in the temperature of the drawer interior is permissible, as long as the temperature of the culture vessels is kept within acceptable limits for encouraging growth of microorganisms.
• FIG. 6 is a top view of the specimen-handling module 12 taken along the line 6—6 in Figure 1. It will be seen that the module, includes a bulkhead 78.
• the bulkhead 78 is fabricated of aluminum or another suitable material, and may be lined with an insulating material, such as a rubber pad.
• Each end of the bulkhead 78 has an adjustment extension 80 which is attached to a corresponding support pillar 82 within the module housing by means of set screws 84.
• Each set screw 84 passes through an elongated slot (not shown) in the extension 80 and into a threaded receiving aperture (not shown) in the corresponding pillar 82. In this way, the bulkhead 78 may be adjusted at each end to move toward or away from the drawer 16 which slides in and out of the drawer receiving area 86.
• the drawer 18 is likewise equipped with a similar sealing arrangement adjacent the left-most side of the drawer in Fig. 1.
• a chamber which is substantially leak-proof is created within the interior of the drawers surrounding the bottle racks.
• the heat generated by heating coil 70 can be substantially confined to the interior of the drawer in which the bottles are held and does not escape from the bottle- holding drawers.
• the seal need not be completely airtight, as long as the heated air is substantially confined within the interior of the drawer.
• the drawers may be opened periodically for addition and removal of bottles without undue heat loss. Indeed, in some instances, a small amount of air leakage can help to more rapidly lower the temperature in the drawers when the temperature rises above the appropriate range.
• the warming means could comprise a heating element which warms the bottle holding racks directly. The heat would then indirectly warm the specimen-holding bottles and the drawer interior.
• the heating means could also comprise a radiator-type system, in which heated water is passed through conduits within the drawer, thereby warming the specimen bottles and the interior of the drawer indirectly.
• the instrument is also equipped with means for periodically and cyclically rocking or agitating the bottles while they are being held within the racks. It is known that such agitation assists in more rapidly detecting microorganisms in the bottle by ensuring that C0 2 generated by the microorganisms diffuses throughout the media and is thereby rapidly brought into contact with the sensor affixed to the bottom of the bottle. (Referring to Figure 8, the sensor is identified by reference numeral 100.)
• FIGs. 4 and 5 show three of the bottle holding racks 20, 22, 24 during the agitation cycle.
• the racks 20, 22, 24 are each pivotally attached to a first pair of rack supports 102a, 102b.
• a pivot pin 106 and bearing (not shown) are used to pivotally mount the first racking support 102a to one side of rack 20 at a position adjacent the back side 109 of the rack 20.
• a second pivot pin and bearing are used to pivotally mount the second racking support 102b to the opposite side of rack 20 in a similar manner.
• bearings made of an electrically conductive material, such as sintered metal are preferred. In this way, the electronic circuitry for the optical units is provided with a path to electrical ground.
• Rack 20 is also attached to a pair of drive supports 112a, 112b at a position adjacent to the bottle-receiving face 116 of rack 20.
• the pivotal mounting of the drive supports 112a, 112b is accomplished by means of pivot pins and bearings.
• Each of the other racks 22, 24 is likewise attached to the racking supports 102a, 102b and the drive supports 112a, 112b in a similar manner.
• drive support 112b is alternately and cyclically driven in an upward direction (illustrated by the arrows in Figure 5) and a downward direction
• Cam follower 178 is rigidly mounted to the cam at a position adjacent the outer circumference of the cam 176. - The cam follower 178, in turn, is slidably received within an oblong slot 180 in arm 182. Arm 182 is rigidly attached to drive support 112b and conveys power thereto. Upon actuation of the motor M, shaft 170, cam 176, and cam follower 178 are caused to rotate. When cam follower 178 reaches the right side of the oblong slot 180 in arm 182, it imparts a downward motion to arm 182 and, thus, to drive support 112b. (The arm 182 displaced in a downward direction is shown in phantom in Fig.
• Fig. 12 is a dwell chart showing the distance of a point P located on rack 20 from a fixed reference point.
• the fixed reference point is chosen as the position of point P when the rack 20 is in its lowermost position.
• the drive mechanism of the present invention causes the distance of travel of the point P from the fixed reference point to increase and decrease in a substantially sinusoidal fashion.
• the slope of the sinusoidal curve is relatively small. Since the slope of the curve is proportional to the velocity of point P (and, therefore, the velocity of the bottle holding racks) , it can be seen that the velocity of the racks near the maximum and minimum travel points is relatively low.
• Such an arrangement also has the significant advantage of reducing the cost of the motor and braking means which can be used in the practice of the invention.
• the distance the racks travel for a given angular movement of the shaft is small at positions near the maximum and minimum distances of travel of the racks, greater leeway in stopping the rotation of the shaft is allowed at these points. Because the rotation need not be stopped to move exacting tolerances, relatively inexpensive motors and braking systems may be used, thus reducing the total cost of the instrument.
• Fig. 14 illustrates an alternative mechanical arrangement for imparting a substantially sinusoidal pattern of motion to the bottle-holding racks.
• pivotal arm 190 is used to convey the rotational motion of the cam 176 to the drive support 112b.
• a first end of the pivotal arm 190 is pivotally mounted at pivot point 192 to the cam 176 at a location near the circumferential periphery of the cam.
• a second, opposite end of the pivotal arm 190 is pivotally mounted at a pivot point 194 to drive support 112b.
• the optical system for mechanically sensing changes in the CO2 sensor is the optical system for mechanically sensing changes in the CO2 sensor.
• the sensor 100 is affixed to the inside of the bottom wall of the culture bottle 120.
• the sensor is made in accordance with the disclosures of copending U.S. patent application S.N. 238,710, filed August 31, 1988 and/or copending U.S. patent application S.N. 609,278, filed November 5, 1990, both of which are entitled “Measurement of Color Reactions by Monitoring a Change of Fluorescence," are assigned to the owner of the present application, and which are incorporated herein by reference and made a part hereof.
• the senor preferably comprises a chromophore layer 122, which consists of a pH sensitive chromophore encapsulated within a gas permeable, hydrogen-ion impermeable matrix, such as ⁇ ilicone. Adjacent the chromophore layer 122 is the fluorophore layer 124.
• the fluorophore layer 124 consists of a fluorescent dye encapsulated within a water and gas impermeable polymer, such as an acrylic polymer.
• the fluorophore layer 124 is preferably positioned above the chromophore layer 122 when the bottle 120 is in an upright position. When placed within an aperture in the bottle-handling rack (see Fig.
• the chromophore layer 122 is thereby situated or sandwiched between the optical unit 46 and the fluorophore layer 124.
• the fluorophore layer 124 has a plurality of radial cut-outs 121, which extend from a position near the center of the fluorophore layer 124 to its periphery. (These cut-outs 121 give the fluorophore layer 124 an appearance similar to that of a "starfish" when viewed from above.)
• Figs. 7 and 8 illustrate the optical unit 46 in detail.
• the unit includes at least one, and preferably more than one, light emission means in the form of a light source.
• a plurality of light sources is preferred, since this helps to ensure excitation light impinges on the area of the bottle where the sensor is located, even when there are variations in the positioning of the sensor on the culture bottle.
• four light emitting diodes (LEDs) 126 serve as the light sources.
• each LED 126 has a plastic lens 127 which defines the cone of light emitted by the LED 126.
• the plastic lenses 127 assist in directing the cone of light emitted by the LED to the vicinity of the sensor and in minimizing stray light.
• the LEDs 126 are positioned around a centrally- located photodetector module 128, which is described in greater detail below.
• the LEDs 126 are positioned so that they fully illuminate the sensor 100 affixed to the inside bottom of a culture bottle 120 placed in an aperture 38.
• the LEDs are also held within a housing 130, which can be molded of a suitable plastic or made by other conventional means.
• the operation of the optical system is best understood by reference to Fig. 8.
• LEDs 126 are selected so that they emit light falling within an emission wavelength range and, preferably, a generally monochromatic light falling within a wavelength range which will excite the fluorophore in the fluorophore layer 124.
• the commercially available LEDs identified above emit a generally monochromatic light having a peak wavelength of 565 nm and a spectral line half width of about 30 nm.
• Light having these characteristics is well-suited to excite the fluorophores oxazine 1,7,0-perchlorate and oxazine 4- perchlorate, which are preferred fluorophores in the practice of the present invention.
• Light from the LEDs impinges on the specimen bottle (and, after passing through the bottle, on the sensor) and excites the fluorophore encapsulated within the fluorophore layer 124, causing it to fluoresce, i.e., emit radiation as it passes from a higher to a lower electronic state.
• Light to be detected emanates from the fluorophore within the specimen bottle.
• This sensor emission light emanating from the sensor has different spectral characteristics from the excitation light, i.e., it has a different peak wavelength.
• Preferred fluorophores emit light at peak wavelengths of approximately 580-650 nm.
• any microorganisms cultured in the media 132 within the bottle 120 produce C0 2 , which diffuses into the gas permeable chromophore layer 122, thereby causing a change in pH within the chromophore layer 122.
• This pH change causes a change in the absorption spectrum of the chromophore.
• Significant growth of microorganisms results in additional production of C0 2 , which causes a further change in the absorption of the chromophore.
• the chromophore is preferably selected so that its absorption spectrum overlaps with the excitation and the emission spectrum of the fluorophore in the fluorophore layer 124.
• the detection unit 128 includes light detection means for converting light energy emanating from the sensor within the specimen bottle into a detectable signal.
• the light detection means takes the form of a photodetector (not shown) , which converts light energy into an electric current. Success has been had with a photodiode made by United Detector Technology of Hawthorn, California, bearing the designation HDT 455.
• the current generated by the photodetector is transformed into a voltage by means of a conventional transimpedance amplifier.
• the voltage which can be correlated to the amount of bacterial growth in the bottle, is then measured by well-known means.
• the detection unit 128 is also equipped with filter means optically interposed between the LED light sources and the photodetector for preventing substantially all light falling within the wavelength range emitted by the LEDs from reaching the photodetector.
• the filter means is carefully chosen in order to achieve substantial isolation between the spectrum of the excitation light and the emission spectrum of the fluorophore. This spectral isolation is best understood by reference to Fig. 13, which is a graph showing schematically both the spectrum of the light emitted by the LEDs and the emission spectrum of the fluorophore. It will be seen that the spectrum of the light emitted by the LEDs has a lower peak wavelength than the sensor light emitted by the fluorophore wavelength.
• Fig. 13 This area of overlap, greatly exaggerated, is represented by the single-hatched area in Fig. 13.
• the filter means is chosen so that the photodetector receives a sufficiently strong fluorescent signal, but the amount of overlap between the spectrum of the excitation light and the spectrum of the fluorescence emission light is minimized and, preferably, eliminated altogether.
• Fig. 13 only light having a wavelength falling within the cross-hatched region is permitted to reach the photodetector; the filter means prevents all other light from reaching the photodetector.
• an area of fluorophore emission is chosen in which the overlap of excitation light and emission light (represented by the intersecting region "a" in Fig. 13) is minimal. It is preferred that the amount of such overlap be less than about 20% of the total signal, more preferably, less than about 5%, and still more preferably, between 1 and 2% or less. In general, to achieve substantial spectral isolation, the difference in peak wavelength between the excitation light and the fluorophore emission should be at least about 10-15 nm and, preferably, 25-80 nm or more. It is also preferred that any small amount of overlap be electronically "subtracted" from the optical signal so that only fluorescence emission is measured.
• the filter means is selected in order to substantially prevent light having a wavelength other than that of the light emitted by the fluorophore — including substantially all of the excitation light emitted by the LEDs 126 — from entering the photodetector.
• the detection system is, to as great a degree as possible, substantially optically “blind” to light having a wavelength other than the light emitted by the fluorescing fluorophore, including the excitation light emitted by LEDs 126.
• the light filter means consists of a longpass filter which prevents light having a wavelength smaller than a particular selected value from entering the photodetector.
• the fluorophore chosen for the fluorophore layer 124 is oxazine 1,7,0-perchlorate or oxazine 4-perchlorate
• the longpass filter is selected to prevent light having a wavelength of less than about 645 nm from entering the photodetector.
• Such an optical arrangement has significant advantages for use in a detection system for microorganisms.
• This optical arrangement permits substantially complete optical isolation between the excitation light and the light emitted by the fluorophore, thus significantly reducing background noise.
• Comparable systems which rely on directly monitoring monochromatic light transmitted by the sensor have significantly more noise because light from the light source can reflect off of other optical surfaces in the instrument (including the bottom of the bottle) and reach the optical system directly.
• the detection system of the present invention is substantially optically "blind" to the excitation light, the fluorophore can be inundated with excitation light, thereby producing an exceptionally strong fluorescence signal, without substantially increasing the noise affecting the detection system. This helps to improve the sensitivity of the system.
• SAMPLE INSTRUMENT PROTOCOL Blood drawn from a patient exhibiting symptoms of bacteremia is drawn and brought to the hospital microbiology laboratory, where it is inoculated into a culture bottle containing media conducive to bacterial growth and labelled with a bar code containing information linking that sample to the patient.
• the instrument operator initiates a command to the minicomputer to open the drawer. If the bottle holding racks are being agitated at that time, a command is sent to stop agitation when the bottle holding racks are near their lowermost agitation position. Alternatively, if optical readings are being taken at that time, the readings are completed before the drawer is opened.
• the system is preferably preprogrammed so that the agitation, heating, and optical reading functions are disabled (and cannot be restarted) while the drawer is open.
• the microcomputer then signals activation of the drawer-opening motor in order to open the drawer.
• the operator draws the bar-code on the culture bottle across the V-shaped channel and bar-code reader located inside the drawer, and the bar code information is scanned into the system.
• This information is transmitted to the microcomputer, which sends a signal to the inside information panel prompting the operator to place the bottle in an available bottle-receiving opening.
• the operator inserts the bottle into the proper opening until it "snap-fits" into engagement with the bottle-retaining means. Thereafter, optical readings for that bottle are associated with the patient information which has been scanned into the system.
• the temperature inside the drawers and, thus, the temperature of the bottles is kept at the preferred temperature for microbial growth.
• the microcomputer signals activation of the fan and heating elements, as required, in order to maintain that temperature within specified limits.
• the microcomputer signals the agitation motor to agitate the bottles using the system illustrated in Figs. 4, 5, and 11.
• agitation of the bottle holding racks is stopped when the bottles are in their uppermost agitation position. While the racks are in this position, optical readings are taken.
• the system is capable of distinguishing between empty openings a: 1 openings which contain bottles by the nature of the optical signal.
• the optical readings are transmitted to the microcomputer where they are associated with the appropriate patient information and stored for later retrieval and use. If the optical reading for a particular specimen exceeds a predetermined threshold, the microcomputer treats that sample as a "positive" and transmits that information to the instrument. An audible alarm is activated to signal this information to those present in the laboratory.
• the microcomputer also sends a command to illuminate the appropriate LED adjacent that bottle to identify the positive culture for the operator. That bottle can then be removed and subcultured so that the infecting bacterium can be identified, and an appropriate treatment regimen (including appropriate anti-microbial agents) can be prescribed for that patient.
• microcomputer Since the microcomputer is also programmed to store and manipulate the data pertaining to the specimens, it is also possible to generate print-outs of the data in various formats, including tables, graphs, and the like.
• a message sent from the host PC to the instrument, which commands the instrument to perform some action, return some data, set some parameter, etc.
• a software module which accepts commands (from the host or from other modules) and either acts on those commands, or relays them to other module(s) for action.
• the context is the memory (code, data, stack) and processor state (i.e. register contents) which "belong" to a given task.
• a block of information passed between tasks In this case, messages are forwarded between tasks by MMX. Commands from the host and responses to the host are a special class of messages.
• An operating system software component which relays messages between tasks.
• a logically grouped portion of software Generally, a module will be contained within a single compilation unit, and will contain functions and data which implenet a particular portion of the requirements for the software system.
• the operating system provides facilities to make multiple tasks, or threads, appear to execute simultaneously.
• the Blood Culture Operating System, and MMX in particular, provide mechanisms for transporting messages between independent tasks.
• MMX provides what can be described a sa many-to-many message system. This means that many tasks may send a particular message, and many tasks may receive a particular message.
• Passing messages involves (at least) three steps in MMX: First, tasks must declare which message they are "interested” in receiving. To send a message, a task "Posts” the message to MMX, which, in turn, delivers it to all other tasks which have declared an intent to receive that message. To receive a message, a task "Pends" for one. The execution of the task is suspended until a message is available for the task.
• Variations on the basic case outlined above include a "pend with time-out,” which limits the amount of time a task will remain suspended when waiting. Message may be "held” - reception deferred until later, while allowing other messages to be passed. Messages which have been hold must eventually be "released” and received.
• the Reller Operating System will be composed of the software components described at the Blood Culture System Design Review held previously. Though the operating system plays a key role in system operation, it will not be discussed extensively in this document. Instead, this document will focus on the software component generally called "the application.” While every software component contributes to the overall functionality of the instrument, it is the application that performs those functions that are most important to the host computer, and eventually, the user. In short, the application is the component that makes the Blood Culture instrument be a Blood Culture instrument.
• the application will be composed of seven modules, and ten tasks: A Coordinator task, responsible for application start-up and time marking; a host communication task, responsible for providing a standard command processor interface and response path for tasks; an access task which handles the actions necessary for letting users into drawers; an analog reading task, which administers the hardware for analog reading; two bottle reading tasks, responsible for handling the timing of and storage of bottle reads; two temperature control tasks, which control the temperature into drawers; and lastly, two agitation tasks, which are responsible for the timing and initiation of bottle agitation within drawers.
• the bottle reading, temperature control, and agitation tasks will be written so the main code body will be reentrant, with independent data segments.
• the machine For each bottle, the machine must read the sensor in bottle and store the information periodically contingent upon the drawer being open and agitation in progress.
• the photoboards sent to ICAAC will comprise the photosystem, with the addition of the lock-in detector.
• Heaters will be installed in each drawer, and the software will be expected to control them.
• New motors will be installed to control the agitation and drawer movement. There will only be crude control of these motors (i.e. Motor on and direction).
• EventName EventName
• commands supported indicates which functions will be provided by the module's command processor. (The command processor pseudocode is not described in this document.)
• braces Special code blocks, that are neither command processors, nor directly related to supporting a system event are indicated by braces.
• the agitation control task attempts to agitate the bottles in "its" drawer as close as possible to the set agitation period. requirements—
• AgDuration Number of FiveSecTicks to agitate bottles.
• AgitatingFlag Boolean indicating that agitation is underway.
• Aglnhibit Integer where non-zero indicates that agitation should be stopped, and no agitation should commence.
• TimeCounter Number of Time_tick periods to go until commencing next agitation phase (on or off).
• EVENT Agitation Inhibited (DEBUG, time, drawer). Increment Aglnhibited flag. Send Aglnhibited*. Pend with no timeout.
• Readlnhibited* was received, we sent a Readlnhibit* message to Bottle*. That means that we intended to commence agitation, and now upon receiving this message, have gotten the go-ahead to do so.
• the control algorithm will be able to time-normalize both readings, and control information.
• TickCounter Number of main clock ticks to remain in present heater state
• HeatDisable non-zero means that the heater will not be activated
• Cell number Disable a cell
• the reading is stored in a circular buffer.
• NoReads Flag that indicates that no readings should be started.
• Bottle Array of (number of bottles in drawer) of records. Active : Flag indicating that this cell should be sampled regularly.
• PeriodCount Number of time periods remaining until next read. events— Readlnhibit*:
• BottleRead*
• VCO measurement may be initiated at any time.
• MUX is selected.
• Drawer channel is selected.
• MUX is switched to appropriate drawer.
• Drawer channel is selected.
• X-S witch is set appropriately (for slow lock -in detect).
• MUX is switched to slow lock-in.
• Delay Number of VRTXticks to delay.
• DelaylnProgress A delay is in progress. A better name would be 'LocklnlnPro gress' .
• Lasttime The last time we started a pend (in VRTXtime)
• Reset DelaylnProgress flag Reset Delay to 0. go execute ⁇ time-out>. ] ] else if Delay ⁇ > 0
• the access task is responsible for primarily two major operations: (1) Notifying the bottle reader tasks, and agitation tasks that a particular drawer is going to be opened, and (2) handling all appropriate drawer parking and movement.

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• 1993
  • 1993-05-24 AU AU44024/93A patent/AU662065B2/en not_active Ceased
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