MXPA00002596A - Individualized and calibrated air tube for spirometer - Google Patents

Abstract

Disposable air tubes (12) having tracking information disposed thereon are disclosed. Spirometer (10, 304) for reading the tracking information on the disposable air tubes (12) are also disclosed. The tracking information automatically ensures that air tubes are not reused among different patients. The tracking information thus reduces or eliminates cross contamination between patients, and increases the accuracy of spirometry (10) readings by reducing condensation buildup within the disposable air tube (12).

Description

i AIR TUBE, INDIVIDUALIZED AND CALIBRATED FOR SPIROMETER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to air tubes for use with spirometers and spirometers that use these tubes for air. More particularly, the present invention relates to air tubes that are disposable and at least partially biodegradable and to calibration and tracking techniques to ensure a high level of precision when disposable air tubes are used with spirometers. 2. Description of Related Art Spirometers are devices that are used to measure the volume and flow rate of exhaled gas and inhaled by a user or patient, for example a human being. Two general types of spirometers measure volume and flow, respectively. For the type of flow, the current gate of the spirometer used to measure the flow is the pneumotachometer, of which one type is the Fleisch.

These measurements are important for physiological studies and for diagnostic analysis of the lung performance of the spirometer user. For example, the effects of various medications used to treat patients with pulmonary or asthmatic problems can be analyzed by checking the volume and flow rate of exhaled gas before and after the administration of medications. Several devices are available in the market, which are known as pneumotachometers, such as the Fleisch neu otacómetro. These devices depend on a laminar airflow beyond an element of resistance. Other spirometers use more sophisticated electronic components in such a way that laminar flow is not required. The measurement of the differential pressure or the pressure difference of the exhaled gas through an element that creates or causes the difference in pressure, is the basis for differential pressure spirometers. In these differential pressure spirometers, it is important that the air tube (pneumotachometer) is precisely configured and located, for example, with respect to the electronic components systems and the pressure detection of the spirometers in such a way that measurements can be made in the Reliable and reproducible. These precisely configured pneumotachometers, instead of being disposable, are made of durable metals or plastics to be long lasting and effective after many uses, without structural degradation. See, for example, Waterson et al., In the U.S. patent. No. 5,137,026, the description of which is incorporated herein by reference.

Since most spirometers involve passing exhaled gas directly from a user's respiratory system to the instrument for measurement, a major complication in using these devices is contamination from one patient to another if the same spirometer is used by both. Various approaches to overcoming this contamination problem have been suggested. A particularly popular approach is to use a nozzle and / or disposable bacterial filter over the entrance to the spirometer. The patient using the spirometer comes into contact only with the nozzle and / or bacterial filter and is able at least in theory to avoid contamination of the rest of the device. Disadvantages of this approach include the relative cost of these nozzles / filters, and the relative inefficiency of these systems. Another approach to overcome this contamination problem is the sterilization between patients or the portions of the spirometer that come into contact with the user and / or the exhaled air. Disadvantages of this approach include having to devote additional capital to sterilization equipment and supplies, having to verify the operation and effectiveness of the sterilization equipment and having to purchase relatively durable and expensive spirometers to support the sterilization processes. A third alternative that has been suggested is the use of disposable spirometry components. See, for example, Norlien et al. In U.S. Pat. No. 5,038,773; Acorn et al. Of U.S. Pat. No. 5,305,762; Karpo icz in the US patent. Do not give. 272.184; Boehringer et al. In the U.S. patent. No. 4,807,641; and Bieganski et al., in the U.S. patent. No. 4,905,709. These prior disposable spirometer components have generally been made of durable plastics or medical grade metals so that even when disposable, the cost of producing these components is relatively high. In addition, these disposable components are relatively difficult to discard and for example, because they are made of durable and long-lasting materials. An element of human error may exist to introduce contamination into a spirometer system, even with the use of disposable spirometer components. For example, a user who does not discard an air tube after use and instead leaves the air tube in the spirometer for subsequent use by another patient, may cause the subsequent patient to be contaminated. Subsequent use of the air tube may also introduce excessive condensation into the air tube, which may result in inaccurate spirometry readings.

The inexpensive manufacture of a relatively inexpensive spirometer component from a low cost and / or biodegradable material has hitherto been prohibitive due for example to considerations of quality control. General industrial specifications require high-quality spirometer components, but the quality of these components may decrease as the components become biodegradable, for example the placement of these components inside the spirometer may also present problems. The placement of the resistive element within each tube can affect the performance of the total spirometer, for example. The resistive element shall be placed in a normal or perpendicular configuration with respect to the inner wall of the air tube and shall also be placed at predetermined exact distances from the two opposite ends of the air tube. Resistive elements of the prior art often do not exhibit linear flow resistance counter-resistance responses. More particularly, resistive elements configured to exhibit good resistance to high flow costs, often do not perform adequately at low flow rates, and on the other hand, resistive elements configured to perform well at low flow rates, often do not provide resistance Ideal at high flow costs. In this way, any possibility of manufacturing a relatively inexpensive spirometer, as an alternative to the durable non-biodegradable metal or plastic components of the prior art, would appear to be flawed due to the manufacturing and performance aspects. These manufacturing aspects include the inconsistencies between various biodegradable, disposable spirometry components that can be produced in a production line, and also include subsequent performance variances between the spirometer components that result from these inconsistencies. The inconsistencies in these components can be increased when they are assembled together or placed in the spirometer. For example, the gate of an air tube may not be perfectly formed, and the subsequent placement of this passage gate in the spirometer may introduce abnormally low pressure readings due to air leakage around the pressure gate. Even the placement of resistive element inside the air tube, as another example, may not be exact between various structures, and accordingly, even a problem of accuracy may be prevalent between existing non-biodegradable components of durable metal or plastic alike . Accordingly, it would be advantageous to provide a means to ensure high performance quality and consistency between various spirometry components of a production line, regardless of whether the spirometer components are plastic metal or biodegradable. COMPENDIUM OF THE INVENTION New calibrated air tubes for use in spirometers and spirometers including these calibrated air tubes have been discovered. The calibrated air tubes present are disposable, so that after use by a patient they are removed from the spirometer and discarded. Follow-up means are incorporated into the spirometer and / or the air tube, to ensure that the air tubes are discarded after use. The tracking means can reduce or eliminate cross-contamination between patients and can increase the accuracy by reducing the accumulation of condensation in the air tube. Each air tube is provided with individualized calibration information. The spirometer can memorize the calibration information in a tube for air determined before using that tube for air, for example and compare that memorized calibration information with calibration information in subsequent air tubes to ensure that an air tube previously used does not Reinsert yourself in the spirometer. In alternate form, special tracking information can be placed in an air tube in addition to or as an alternative to the calibration information. The air tubes are preferably almost completely biodegradable, can be manufactured relatively cheaply and are capable of producing high and consistent performance characteristics. As used herein, the term "biodegradable" means that the material component is decomposed into more environmentally acceptable components, such as carbon dioxide, water, methane, and the like, by natural biological processes such as microbial action, for example are exposed to of typical embankments, in no more than five years, preferably not more than three years and also preferably not more than one year. Having the biodegradable calibrated air tube provides substantial advantages. First, when the air tube and the resistive elements are discarded, the environmental load of this waste is reduced, for example to a tube for non-biodegradable air, such as those made from plastics or conventional metals. In addition, because the air tube and the resistive elements are biodegradable, they can be made from materials that are cheap and abundant. In this way, the current air tubes are relatively inexpensive, easy and simple to produce. A subsequent calibration of the air tubes takes into account any discrepancies in size, shape and performance of the air tubes. Since the present air tubes can be processed inexpensively, replacing a used air tube with a new air tube is used without substantial economic impact. In addition, the present air tubes can be replaced in the spirometer, very easily. These advantages promote compliance by the operator since the spirometer operator (for example, the care provider or the patient operating the spirometer) is more likely to change the air tubes present after each treatment or patient, reducing in this way the risks of contamination and the spread of diseases, for example tuberculosis and other disorders of the respiratory system, AIDS, other systemic conditions and the like. Spirometers that use the calibrated air tubes present provide cost effective, reliable and reproducible measurements (air tube in air tube) of the user's lung performance, with reduced contamination risk. In short, the present disposable biodegradable calibrated air tubes are economical and easy to produce to acceptably accurate specifications (for reproducible performance) they are effective and reliable in use, and are conveniently and effectively discarded in an environmentally acceptable or safe manner, for reduce the risks of contamination caused by the use of the spirometer. Brief Description of the Drawings Figure 1 is a side view of a spirometer according to the present invention showing a portion of the electronic components cut out of the hand unit. Figure IA is a front side view of the spirometer shown in Figure 1. Figure 2 is an exploded view of the air tube of the present invention.; Figure 3 is a cross-sectional view of the air tube of the present invention; Figure 4 is a top plan view of the resistive element of the present invention; Figure 5 is a partial cut-away view, upper front view, in perspective, of the air tube shown in the spirometer shown in Figure 1. Figure 6 is a somewhat schematic illustration showing a spirometer according to the present invention. Figure 6A is a cross-sectional view taken generally on line 6A-6A of Figure 6. Figure 7 is a cross-sectional view taken generally on line 7-7 of Figure 1. Figure 8 is a side view of an alternative embodiment of a spirometer according to the present invention. Figure 9 is a rear side view of the spirometer shown in Figure 8. Figure 10 is a perspective view illustrating the structure for bar code reading of the spirometer of the currently preferred embodiment. Figure 11 is a circuit diagram illustrating a specific implementation of the bar code reading structure of Figure 10; Figure 12 is a schematic representation of a linear configuration of photodiodes for receiving light from a bar code label according to the currently preferred embodiment; and Figure 13 is a perspective view of an autofocus lens structure used to focus light on the structure of the linear photodiode configuration in accordance with the currently preferred embodiment. Figures 14 and 15 illustrate perspective views of a spirometer design according to the currently preferred embodiment. Detailed Description of the Drawings With reference to Figures 1 and IA, a spirometer according to the present invention, generally shown at 10, includes a disposable, biodegradable air tube 12, a housing 14 and electronic control components 16. Spirometer 10 is what is currently known as a differential pressure spirometer and generally operates in a manner similar to the spirometer described in the US patent No. 5,137,026 issued to Waterson et al. Previously noted. The air tube 12 is described with reference to Figures 2 and 3. The air tube 12 includes a first tubular segment 18, a second tubular segment 20 and a collar tube 21. A resistive element 22 couples between the first tubular segment 18 and the second tubular segment 20. The air tube 12 and the resistive element 22 are preferably about ninety-nine percent biodegradable. The tubular segments 18, 20 and 21 are made of cardboard or heavy biodegradable paper, for example in a manner similar to conventionally made cardboard tubes, such as those used with toilet paper and the like. These segments 18, 20 and 21 are preferably coated with a satin layer. The resistive element 22 preferably comprises biodegradable material having good memory characteristics. As it is currently incorporated, the resistive element 22 comprises a Nomex material. The resistive element material 22 can alternatively comprise any nylon or other material that is somewhat resistant to moisture. As currently incorporated, resistive element 22 has an approximate thickness of .076 mm (.003 inch), but other thicknesses may be employed according to design parameters. The resistive element 22 is first fastened to either the first tubular segment 18 or the second tubular segment 20, and then the other tubular segment 18 or 20 is then attached to the resistive element 22. A biodegradable adhesive is preferably used. As currently incorporated, an outer diameter of the first tubular segment 18 is equal to an outer diameter of the second tubular segment 20, and the outer diameter of the resistive element 22 is equal to the outer diameter of the first tubular segment 18. An inside diameter of the tubing collar 21 is approximately equal to the outer diameter of the first tubular segment 18. The collar tube 21 is adapted to engage both the first tubular segment 18 and the second tubular segment 20. Although adhesives are preferably used to hold the resistive element 22 between the first tubular segment 18 and the second tubular segment 20, the intimate frictional fit of the collar tube 21 on the first tubular segment 18 and the second tubular segment 20, may be sufficient only to hold the resistive element 22 between the first tubular segment 18 and the second tubular segment 20. The distal end 23 of the collar tube 21 is flush with the distal end 25 of the first tubular segment 18, when the collar tube 21 is suitably clamped both on the first tubular segment 18 and the second tubular segment 20. Additionally, a notch 27 that preferably it comprises a semi-circle punched at the distal end 23 of the collar tube 21, preferably aligned with a gate 24 of the second tubular segment. The gate 24 of the tubular segment 20 preferably comprises a punched circle in the second tubular segment 20. The groove 27 and / or the gate 24 can be formed in the collar tube 21 and / or the second tubular segment 20 either before or after of assembling the three pieces 18, 20 and 21. After assembling the three elements 18, 20 and 21, the gate 24 opens directly into a hollow space (Figure 3) of the air pipe 12. Figure 3 illustrates the air tube 12 in an assembled state. Although a three-piece configuration of the air tube 12 is currently preferred, these three pieces 18, 20 and 21 can be replaced by a single tube, for example and / or the resistive element 22 can be attached to an annular ring (not shown) that is inserted inside the simple tube. Figure 4 illustrates a planar top view of the resistive element 22, according to the currently preferred embodiment. The resistive element 22 comprises a central opening 32 and a plurality of slots 34 that extend radially from the central opening 32. Each pair of adjacent slots 34 forms a hinged window 36, which as currently incorporated comprises an arrowhead shape. Each hinged window in the shape of an arrowhead 36 comprises a tip located near the central opening 32 and a neck 38 located remote from the central opening 32. As currently incorporated, the resistive element 22 comprises eight hinged windows 36, but larger numbers or smaller hinged windows 36 can be used according to design parameters. The width of each neck 38 controls the flexibility of the corresponding hinged window 36. A larger neck makes the corresponding hinged window 36 less flexible, and a smaller neck 38 makes the corresponding hinged window 36 more flexible. A human patient who blows at one end of the air tube 12 generates an air flow through the resistive element 22, which typically can comprise an air flow expense of between 0 and 16 liters per second. The resistance that is provided by the resistive element 22 should ideally be approximately linear on these various air flow expenses. Resistive elements of the prior art comprise a disk with a single opening, for example they do not have linear relationships of flow rate against pressure. A disc-shaped resistive element of the prior art having good strength of less than 1.5 cm of water per liter per second at about 12 liters per second, for example will not have good resistance to lower flow costs. More particularly, this conventional disk-shaped resistive element will have a very low resistance to low flow costs, which is unacceptable. The resistive element 22 of the present invention utilizes unique hinged windows 36 having collars 38, which can be engineered to adjust the resistance of the resistive element 22 to various flow rates. The resistive element 22 of the present invention is adapted to provide an ideal resistance of less than 1.5 cm of water per liter per second, at an approximate flow rate of 12 liters per second, but in contrast to a conventional disk-shaped resistive element, the resistive element 22 of the present invention also provides good resistance to low flow costs. Generally speaking, the resistive element 22 provides a very good approximate linear flow-versus-resistance response, for flow rates between zero and 16 liters per second. At high flow rates, hinged windows 36 are widely opened to provide good strength that is not too high. At low flow costs, the hinged windows 36 open very little, so as to provide a good resistance which is not too low. According to the presently preferred embodiment, an angle between two of the slots 34 is approximately 45 degrees, and each of the slots 34 has an approximate width of .508 mm (.02 inch). A preferred width of each of the perpendicular hinged portions 37, which is used to control the width of a neck 38 is approximately 1018 mm (.04 inch). The diameter of the resistive element 22 is preferably 27.68 mm (1.09 inches) plus or minus .0127 mm (.0005 inch) and a width between a line 39 that bisects one of the hinged windows 36 and another line 41 that passes through a slot 34 from approximately 1,588 mm (.0625 inch) plus or minus .127 mm (.005 inch). An important element of the resistive element 22 of the present invention is the resistance provided at low flow costs, since typically unhealthy patients are unable to generate high flow costs. The same resistive element also works equally at high flow rates. Resistive element 22 provides good resistance to various flow expenses, regardless of whether the patient exhales or inhales. With reference to Figure 5, the air tube 12 includes an open inlet 46 and an open outlet 48. The area surrounding the open inlet 46 is sized and adapted to fit in the mouth of a human being. This nozzle area is used by the patient using the spirometer 10 (Figure 1) when placing the area 46 in the mouth and exhaling in the hollow space 30 of the air tube 12. Returning to Figure 1, when you want to use the air tube 12, is unpacked and coupled to the housing 14. In particular, the air tube 12 is coupled to the housing tube 51. The housing tube 51 includes a tab 52, which is adapted to engage within the n 27 ( Figure 2) of the air tube 12. Before the air tube 12 is placed in the accommodation tube 51, the n 27 is aligned with the gate 24 (Figure 2) and as it is currently incorporated, it is manually aligned by the user just prior to insertion into the accommodation tube 51. When the n 27 is aligned with the gate 24, the gate 24 will align with the pressure sensing foot 76 as illustrated in Figure 6. More particularly, a foot fitting of pressure detection 76 that preferably comprises a suction cup shape 77, fits around the gate 24 for an airtight fit. The suction cup shape accessory 77 preferably comprises vinyl or silicone rubber, and is adapted to provide a good fit around the gate 24, so as to attenuate any air leakage at this interface. Consequently, the patient's breathing is not introduced to the pressure sensing foot 76 and contamination of the pressure sensing leg 76 is prevented. After the n 27 of the air tubing 12 is placed inside the accommodation tube 51 and more particularly placed on the alignment tab 52, the distal end 23 of the collar tube 21 should be flush with the distal end of the housing tube 51. At this point, the spirometer 10 is ready for use. It should be noted that the air tube 12 is longer than the receiving tube 51 and when properly fitted to the receiving tube, it extends beyond one end of the receiving tube. The relatively long air tube 12 reduces the risk of exhaled air from the user of the spirometer that comes into effective contact with and contaminates the housing. Figure 6 illustrates the general operation of a spirometer, generally shown at 10. The following is a general description of the operation of the spirometer 10 after the air tube 12 is properly located and positioned relative to the pressure detection leg 76. The method and calibration apparatus of the present invention will subsequently be discussed in greater detail after the general operation that is now provided. This general description is applied using any spirometer, such as the spirometer 10, according to the present invention. The gate 24 (FIG. 2) communicates with the leg for pressure detection 76. As an additional protection against contamination, the pressure detection leg 76 may be equipped with a filter, although this is not required. The pressure detection leg 76 communicates with a differential pressure transducer or "manometer" 80 which may for example be a transducer sold by Motorola under the brand MPX 2020D. The pressure transducer 80 generates an electrical signal in a pair of output wires 82 and 84, this signal is proportional to the differential pressure between the pressure detection leg 76 and a detected atmosphere pressure. This signal is amplified by a differential amplifier stage 86 and fed to an analog-to-digital converter 88 that converts the output of the amplifier into digital signals. The output of the converter 88 is fed to a microprocessor 90, which is part of the electronic control components 16. The microprocessor 90 uses calibration data supplied by the encoded information in the air tube 12, in combination with an algorithm stored in a ROM 92, for performing various calculations on the signal from the converter 88 and displaying the calibrated final results, for example volume and flow rate in the display 94, for example a liquid crystal display module or conventional monitor. The microprocessor 90 is energized by an energy source 91, either for example a battery or a connector capable of being coupled or connected to a conventional power line voltage source. The switch 96 can be activated to initiate the operation of the spirometer through the microprocessor 90. The results during each measurement can be stored in a RAM 98 for future reference. An input / output gate 100 can also be provided to allow changing the programming of the microprocessor 90. In addition, the microprocessor 90 can be programmed in such a way that before command, it can download the accumulated results in the RAM 98 through the input / output gate 100, to a printer or computer. The patent of the U.S.A. No. 5,137,026 to Waterson et al. Provides details regarding the operation of a conventional spirometer. When a patient concludes a diagnostic treatment or exercise using the spirometer 10, the biodegradable air tube 12 is removed from the housing tube and discarded in an environmentally safe manner. As illustrated in FIGS. 1 and 1A, the housing 14 is structure to be held by a user's hand. For example, the arrow 102 of the housing 14 is configured for easy clamping by hand. In addition, indentations for finger 104 are provided to make it even easier to hold this device by hand. Indentations for finger 104 can be placed in different places in alternate modes, or they can be omitted altogether in other alternate modes. The embodiment shown in Figures 1 and IA includes electronic control components 16 located within the portable housing 14. Communication with computers or external printers can occur through cable 106 that can be connected to the converter using a plug-in-socket 105, such as a conventional RJ-11 quick plug plug in the housing 14. As is currently preferred, communication may also occur through an additional infra-red Data Association link (IRDA) Infrared Data Association) that is conventional and operable between the housing 14 and the external computer or printer. The electronic components in the housing 14 are preferably energized by a battery pack, such as a conventional rechargeable nickel-cadmium battery. If this battery pack is used, the housing 14 includes a gate through which the battery pack can be charged. In the embodiment shown in Figures 1 and IA, the microprocessor 90 may be a dedicated microprocessor that includes a transparent overlay pushbutton structure and specifically adapted to control the operation of a spirometer. Alternatively, the microprocessor 90 may be a component of a general purpose personal computer, which includes a full size keyboard, video monitor, hard disk drive and printer. The dedicated microprocessor is particularly advantageous due to its relative simplicity, reduced cost and ease of use. In addition, the arrow 102 of the housing 14 includes a tapered portion 107 as illustrated in Figure IA, which facilitates placement and maintenance of the housing on a flat surface, for example between uses. The embodiment shown in Figures 1 and A, is useful as a completely new spirometer, or the air tube 12 and housing 14 can be used for retroactive modification of an existing spirometer. For example, an existing spirometer includes a hand-held unit comprising a permanent breathing tube, a limb or leg for pressure sensing, a pressure transducer, an amplifier and an analog-to-digital converter, and is connected to a control system. dedicated control, which operates in a manner substantially similar to the electronic control components 16. Simply by replacing the existing portable unit, with the housing 14 and the components coupled to or placed in the housing, a retroactive modification spirometer is produced, which has many of the advantages of the present invention. Figure 7 shows a cross-sectional view of the spirometer 10 of Figure 1, taken on line 7-7 of Figure 1. Another embodiment is illustrated in Figures 8 and 9. This spirometer, shown generally at 210, is except as expressly stated herein, structured in a manner similar to the spirometer 10. Spirometer components 210 corresponding to components of the spirometer 10 have corresponding reference numbers increased by 200. The fundamental differences between the spirometer 210 and the spirometer 10, have to do with the configuration of the air tube 212 and the configuration of the accommodation tube 251. The air tube 212 is structured substantially similar to the air tube 12 except that in the region near the open outlet 248, two air gates are provided. location 107 and 108. The housing tube 251 is structured to act as a support for the air tube 212, instead of surrounding it to the air tube 212, as the receiving tube 51. In addition, the receiving tube 251 includes two upwardly extending projections 109 and 110 which are positioned to receive when locating the gates 107 and 108, respectively, when the tube air 212 is coupled to housing tube 251. With projections 109 and 110 engaged in or received by location gates 107 and 108, gate 224 (not shown) is suitably aligned with pressure detecting leg 276 (not shown) . As illustrated in Figures 8 and 9, a transparent overlay control button 112 of the microprocessor 90 is located on the arrow 302 of the housing 214. In addition, this preferred mode comprises greater ROM, and the display 94 is located in housing 214 below the transparent overlay button 112. In the spirometer 210, the power source 91 is a battery pack, such as a conventional rechargeable nickel-cadmium battery., and is located within the housing 214. The gate 114 of the housing 214 is adapted to provide communication between the battery pack 91 and a conventional battery charger for recharging the battery pack when required. The I / O (I / O) gate 100 is also transported through the housing 214 and provides convenient communication between the microprocessor 90 and a computer or printer, when it is desired to download information from the electronic circuits 111 to this other device. As with the embodiment of Figure 1, an IRDA optical damper is also arranged on arrow 302. Spirometer 210 is a self-contained unit that can be operated by a single patient. In order to operate the spirometer 210, the air tube 212 is coupled to the housing tube 251 in such a manner that the projections 109 and 110 engage location or location gates 107 and 108 respectively. The patient then activates a switch on the transparent overlay button 112 and uses the spirometer 210 for any desired treatment and / or diagnostic procedure. When it is desired to remove the air tube 212 from the housing tube 251, the biodegradable air tube 212 simply rises from the housing tube 212 and can be discarded in an environmentally acceptable manner. Again with reference to Figure 6, a character recognition unit 304 is placed inside the housing 14 of the spirometer 10. The character recognition unit 304 preferably comprises a device for recognizing bar code strips The character recognition unit 304 is placed inside the housing 14 to align with a sequence of characters 306, preferably bar code type strips in the air tube 12, when the air tube 12 is placed inside the housing 14. According to the present invention, calibration information and / or tracking information with respect to the air tube 12 it is encoded within the character sequence 306. This coded information is read by the rejection unit. knowledge of characters 304 and transported to converter 88 via line 308 and then to microprocessor 90. Converter 88 preferably comprises eight feeds. Out of these eight, two reception pressure transducer signals 80, one receives tube flow pressure, and one for rmomanometry (nasal air pressure). Rhinomanometry feeding can be used to accept a pulse oximetry feed in an alternate mode. As currently incorporated, the character recognition unit 304 is placed inside the housing 14 of the spirometer 10 to automatically read the sequence of characters 306, but alternatively, this reading of information from the character sequence 306 can be done manually . Human-readable characters can be placed next to the sequence of characters 306, for example. Additionally, the reading of character sequence information 306 can be performed before, during or after each reading by the spirometer 10 according to the design preference. After an operation of the spirometer 10 has been performed, the air tube 12 should be discarded in accordance with the present invention. Disposal of each air tube after each use reduces or prevents cross-contamination of patients. The disposal of each air tube after use can also reduce the accumulation of condensation in the air tube, thereby increasing the accuracy. In the currently preferred embodiment, the spirometer 10 compares character sequence information 306 of each new air tube 12, to ensure that a new character sequence 306 is present. Character sequence information 306 in this way preferably it is read by the character recognition unit 304 before each operation of the spirometer 10. The information read by the character recognition unit 304 is stored in the RAM 98 for future reference. If a new sequence of characters 306 is not detected, the spirometer 10 considers that the air tube 12 has not been replaced after previous reading. The character recognition unit 304 reads information in the character sequence 306 before each new operation of the spirometer 10, to ensure that the previously used air tube has been removed. If the information in the character sequence 306 corresponds to the information stored in RAM 98, corresponding to the character sequence previously read 306, then a determination is made that the previously used air tube is still present. Upon this determination that the previously used air tube has not been removed, the spirometer 10 will cease to operate totally or partially, according to the present invention. For example, the spirometer 10 may refuse to provide a reading until a new tube for unused air is installed. Alternately, a warning such as a visual or audible alarm will be activated. In another mode, the spirometer will cease to operate totally or partially and an alarm will be activated. The spirometer 10 may comprise a comparator for each integral character sequence 306 of each air tube, or may be configured to compare only a portion of each character sequence 306 of each air tube, to avoid reuse. A tracking character or single tracking character sequence is preferably provided within each sequence of characters 306 in addition to calibration information. The spirometer 10 can be programmed to maintain a record of past air tubes that have been read. For example, the spirometer 10 can be configured to maintain a record of the last 100 air tubes that have been read by the spirometer 10. Prior to each new operation of the spirometer, the information of the new character sequence is compared with information in the Character sequence of the last 100 air tubes to ensure that an old air tube is not being reused. The character recognition unit 304 is preferably an optical character recognition unit, adapted to read a sequence of bar code characters 306, but alternatively, other techniques that convey information can be implemented.

For example, recognition of magnetic characters, recognition of optical alpha numeric characters, recognition of optical symbols, etc., can be employed, provided that the calibration information regarding the air tube 12 is transported to the microprocessor 90. Preferably, the unit Character Recognition 304 comprises a linear structure for recognizing bar-type codes. Figure 6A illustrates a cross-sectional view taken on line 6A-6A of Figure 6. As currently incorporated, a light source 310 projects light in the direction of the arrow Al over the sequence of characters 306 placed on a surface of the air tube 12. As currently incorporated, the character sequence 306 comprises a bar code label or alternatively a bar code printed directly on the air tube 12. Light from the light source 310 is reflected from the character sequence 306 in a direction of the arrow A2 and enters a self-focusing lens structure 313. The light of the auto-focus lens structure 313, subsequently focuses on a linear structure of Photodiodes 315. The linear structure of photodiodes generates an electrical output, which is subsequently interpreted by the converter 88 and then by the microprocessor 90 (Figure 6) to discern the tracking information and / or calibrating information contained within the character sequence 306. In accordance with the currently preferred embodiment, a wedge-shaped black plastic support 318 is placed between the light source 310 and the auto focus lens structure 313 and the linear array of photodiodes 315. The black plastic wedge-shaped support 318 is adapted to hold these three elements 310, 313 and 315 for proper alignment within the housing 14 of the spirometer 10. A perspective view of the recognition unit of characters 304 of the currently preferred embodiment is illustrated in Figure 10. Light from the light source 310 focuses on the character sequence 306 placed in the air tube 12. Reflective light is received by the auto-lens structure. focus or autofocus 313, which as presently incorporated, is positioned at an angle 321 of approximately 45 degrees from the light source 310. Both the light source 310 and the auto-focus lens structure 313 have lengths that are substantially parallel to a centerline scan 323 that passes through the character sequence 306. The linear structure of photodiodes 315 is positioned substantially parallel to the autofocus lens structure 313, and is adapted to receive focused light from the autofocus lens structure 313. An external light stop 325 is placed on a portion of the autofocus lens structure 313, and another external light stop 327 is placed on the linear structure of the photodiodes 315. Figure 13 illustrates the light stop with fastener 325 adapted to accommodate the autofocus lens structure 313, in accordance with the currently preferred embodiment. The light stop 325 preferably comprises black plastic, and can be frictionally adjusted around the self-focusing lens structure 313 and / or subject using an adhesive. Alternatively, less expensive light stop techniques can be implemented, according to design preference. As previously mentioned with reference to Figure 6A, both the light source 310 and the self-focusing lens structure 313 and more preferably also the linear structure of the photodiodes 315 are placed on a wedge-shaped black plastic support 318 The wedge-shaped black plastic support 318 provides the correct angle between the light source 310 and the self-focusing lens structure 313 and the linear array of photodiodes 315. The black plastic wedge-shaped support 318 also facilitates adequate spacing of the light source 310, the self-focusing lens assembly 313 and the linear array of photodiodes 315 with each other and with respect to the air tube 12. The wedge-shaped black plastic support preferably comprises a black color to suppress light reflections. The total conjugate focal length 333 of the autofocus lens assembly 313 is preferably approximately 9.4 mm, which is measured from an internal sensitive surface of the linear structure of photodiodes 315 to the target surface of the character sequence 306. As it is currently incorporated , the self-focusing lens structure 313 comprises a set of Selfoc1"'lenses manufactured by Nippon Sheet Glass Co., Ltd. This self-focusing lens structure 313 is positioned halfway between the linear structure of photodiodes 315 and the sequence of characters 306 such that both the linear array of photodiodes 315 and the character sequence 306 are at focal points of the autofocus lens assembly 313. As currently incorporated, the autofocus lens structure 313 is set to 2.5 mm of the sequence of characters 306 and 2.5 mm of the linear array of photodiodes 315. A portion with an approximate width of 1 mm of the image of the sequence of acters 306 on the character sequence center line 323 is transferred by the autofocus lens array 313 to the linear array of photodiodes 315, when the character sequence 306 is illuminated by the light source 310 as it is currently incorporated, the set of autofocus lens 313 is approximately 18 to 20 mm in length, and comprises a single row of lenses 336. The autofocus lens assembly 313 is preferably slightly longer than the linear array of photodiodes 315, which is approximately 16 mm long, to ensure that the complete linear array of photodiodes 315 receives an image, allowing misalignment and / or lens damage of plus or minus 1 mm in the self-focusing lens assembly 313. Although the orientations described above, Distances and tolerances are preferred, different orientations distances, and tolerances can be implemented in alternate modes to generate similar results. The two focal points of an exemplary single lens 336 of the autofocus lens assembly 313, which are not to scale, are illustrated at 339 and 340. The linear array of photodiodes 315 preferably comprises an intelligent optical detector manufactured by Texas Instruments, model number TSL215, and comprises a set of 128 pixels as charge in a linear array of 128 X I. The linear array of photodiodes 315 is preferred over a charge coupler device (CCD = Charge Coupled Deviee) due to ease of use, Between other reasons. The linear array of photodiodes 315 comprises integrated synchronizer generators, analog output buffers, and digital latch circuits, which would otherwise be required as a CCD circuit. The focal point 340, for example, is focused approximately 1 mm below the top surface of the photodiode array 315. As currently incorporated, in addition to the light stop 327, a transparent plastic package 344 is placed on the surface sensitive 346 as illustrated in Figure 12. Central scanning line 323 projects onto sensitive surface 346, as illustrated by line 348. As currently incorporated, focal point 340 (Figure 10) is approximately 1 mm below the upper surface of the transparent plastic package 344, and projects onto the sensitive surface 346 of the assembly. The light is projected onto the sensitive surface 346 of the linear array of photodiodes 315, when the light source 310 is activated by the microprocessor 90 (Figure 6). As illustrated in Figure 11, the microprocessor 90 activates the light source 310 using the "lighting-ignition" signal line 350, which is connected to a parallel port terminal 352 of the microprocessor 90 as it is currently incorporated, the light source 310 comprises a set of four-element light-emitting diodes, of approximately 45 milicandelas (lu ens / ster), having a wavelength of approximately 635 nanometers, and which is an approximately Lambertian source. The light source 310 is derived with 20 milliamps of current in half, two lamps and 25 milliamps of current in the end lamps, to provide even illumination over the character sequence 306 according to the present invention. The light source 310 provides approximately 23 microwatts per square centimeter of illumination, and is placed approximately 7 millimeters from the target bar code, as illustrated by the reference number 354. The light stop 325 between the light source 310 and the autofocus lens assembly 313 suppresses parasitic light. The present invention incorporates a wavelength of 635 nanometers to roughly correspond to the peak detector responsiveness of the linear array of photodiodes 315 that is approximately 750 nanometers. The sensitivity obtained in the linear set of photodiodes 315 approximately is 80% of the maximum linear set sensitivity at 100% at 750 nanometers of wavelength. The light source 310 has a length of approximately 16 millimeters. As currently incorporated, the light source 310 is only activated by the microprocessor 90 during bar code readings, since evidently, the activation of the light source 310 dissipates energy. Both the light source 310 and the linear array of photodiodes 315 preferably comprise integrated circuits which are mounted on a flexible PC board, and form a dihedral angle 321 with each other of 45 degrees. With reference to Figure 11, the image integration time of the photodiode array 315 begins with a short pulse on line 360 by the microprocessor 90 at a series power terminal 362 of the photodiode array 315. After approximately 1 to 10 milliseconds, a second pulse of series power is fed to the linear array of photodiodes 315 on line 360. After this second series supply pulse, the image is read on the video output terminal 364 when synchronizing the synchronization terminal 366 between 10 kilohertz and 100 kilohertz, using 129 or more synchronization pulses. The resulting signal is placed on the serial video output line 368. During the aforementioned synchronization operation, the serial video output, which comprises an analog voltage, is read by the analog to digital converter (A / D). ) 370, which preferably comprises a precision of 12 bits and a power range of 0 to 5 volts. The analog-to-digital converter 370 outputs digital data in the data bus 373, which reflects the amplitude of each video pulse and consequently the darkness of each detector pixel in the linear set of photodiodes 315. This digital data in the bus duct data 373 is subsequently read by microprocessor 90. Analog to digital converter 370 is controlled by microprocessor 90, and has a conversion time of approximately 10 microseconds. Accordingly, the linear array of photodiodes 315 can be synchronized up to 10 microseconds (100 kilohertz). The linear array of photodiodes 315 is energized by a 3-terminal voltage regulator 375, to keep the power supply interference and interference of the video set to a minimum. Although the Texas Instruments TSL215 product is currently preferred, a more recent product from Texas Instruments, TSL1402 can be used instead. This last model comprises twice as many pixels in the same length of 16 millimeters. The model has twice the resolution and will allow more digits and more reliability. This later model is compatible with terminals, so that the number of synchronization cycles can simply be changed from 129 to 257, and is less susceptible to optical saturation. The TSL1402 also does not require the initial pixel load period of 40 milliseconds and will provide double speed and accuracy. The sequence of characters 306 preferably comprises a bar code which already has an interleaved sequence 2 of 5 ITF, provides approximately 3 decimal digits of calibration data plus a check sum digit or alternatively, may comprise a direct binary code . The direct binary barcode is currently preferred, and is configured to provide approximately five and a half digits plus a binary verification amount of approximately six bits. The binary code will be non-return-to-zero (NRZ) with bars and spaces of constant width, plus a starting mark. This configuration ensures that the total width of the code is constant and allows one millimeter on each side for code location error. The minimum black and white bar widths in the bar code are chosen from at least 2 to 3 pixels wide in the linear array of photodiodes 315. Since the linear array of photodiodes has spacing of .125 millimeters between photodiodes, the width Minimum bar is approximately twice that width. This configuration ensures that at least one pixel position in the video output 368 of the linear array of photodiodes 315 goes completely low or high since a pixel in the set 315 is totally black or white and is not located halfway between a bar black and a white area. The integral high or low voltage in relation to other voltages in the video output 368 of the linear array of photodiodes 315, is decoded by software (software) to positively indicate a bar position. Since the light source 310 is preferably of constant intensity, variances in the light source intensity between units and over time are compensated for by the present invention. For this reason, and to compensate for the efficiency of the detector, the light integration of the linear array of photodiodes 315 is adjusted. The level of the video image that is read from the linear array of photodiodes 315 can be increased by increasing the time between pulses of series power on line 360, that is, the light integration interval time. After each bar code is read, if the bar code amplitude data is very low, the integration time is adjusted until the amplitude is sufficient to detect white-to-black differences. The total amplitude of the integral serial video data stream of each read operation forms a non-linear curve due to changes in light intensity on the light source. In software (software) according to the present invention, an average operating differential or other indicator indicates the approximate threshold from white to black over the entire length of video data. This average will be used to detect white data from blacks by comparing software (software). High frequency interference is separated by filtering software (software) and the resulting data stream comprises a bar code image. As it is currently incorporated, this resulting data stream is decoded by the binary NRZ method or the interleaved method 2 to 5, depending on the code used. This NRZ format changes the bar code color if the data bits do not change and the bar code color does not change when the bits change. The resulting current, after being decoded by either the binary method NRZ or the integrated method 2 through 5, comprises the original binary or decimal number that was originally coded in the air tube 12. This number is then used to calibrate this detector to Spirometric flow. The linear array of photodiodes 315 must initially be preconditioned by an operation period of 40 milliseconds, before each bar code read, in order to allow each of the 128 pixels to change from white to black or vice versa correctly. During this pre-conditioning period, the light source remains on, and the barcode data is ignored. Subsequently, several barcode exprers are made until the correct data is obtained, judging by the checksum embedded in the barcode. Accordingly, the total read operation is approximately 40 milliseconds plus 5 milliseconds per bar code scan or approximately 100 milliseconds. Each bar scan requires 128 times 10 microseconds of minimum time, or 128 times 100 microseconds of maximum time. The time is determined by the required integration time as mentioned above. The light source 310 is lit evenly during all bar code scans, up to 100 milliseconds, and does not turn off during scans of 5 milliseconds, as the pixels have to be illuminated throughout the integration time. An embedded 16-bit microprocessor synchronizer is programmed to develop repetition time periods of 10 to 100 milliseconds with each period that generates an interrupt. A synchronization switch initiates a routine that outputs the start integration pulse if required, and then outputs 129 synchronization pulses, generated by the synchronizer. At each synchronization pulse, the analog to digital converter 370 is read by the microprocessor 90 via the data conduit 373 and stored for further analysis. After completing the 129 synchronization pulses, the synchronizer is stopped and the data is analyzed by the microprocessor 90 to find the black-white threshold level in motion, for each pixel using filtering and continuous averaging. The data is then filtered in software (software) and compared to the threshold level in motion, before becoming barcodes. In the currently preferred mode, approximately 8 bar code scans are taken and stored at the same time, requiring 8 times 12.5 mi 11 seconds or 100 milliseconds of maximum time, so that the initial pixel load time of 40 milliseconds does not It has to be repeated. Regarding the linear autofocus set 313, this structure may have to be adjusted to focus exactly on the sequence of characters 306 within plus or minus .3 millimeter unless this is guaranteed by the manufacturing process. The focal length may have to be adjusted in a light environment, while a diagnostic program runs the microprocessor 90 and continuously scans the 306 character sequence, sending out the percent of read errors when reading the character sequence 306. This focal length is preferably adjusted until errors are minimized. Examples of random or worst case bar codes will be used preferably for this procedure. According to the method of calibrating an air tube of a subject 12 and placing the calibration information in the air tube 12 in the form of a sequence of characters 306, a large batch of initial samples of air tubes 12 is tested. from a manufacturing line. As currently incorporated, the test procedure comprises subjecting each flow tube 12 to an air stream of 7.5 liters per second in the expiratory direction. A detector leg similar to that shown in Figure 6 at 76 is placed on the through gate 24 (Figure 2) of the air tube 12, and this detection leg is connected to a high precision pressure sensor. A mechanical resonance filter may be required in the tube. This measured pressure, in response to the airflow of 7.5 liters per second in the expiratory direction, is noted for each tube and subsequently, a similar measured pressure for the same air flow rate in the direction of inspiration is obtained for each air tube 12. The present invention recognizes that, although there are manufacturing differences between each air tube 12, the air flow feed curve versus pressure outlet for each air tube 12 is remarkably similar. More particularly, this air flow feed curve versus pressure outlet for each flow tube 12 can be modeled mathematically by a third order polynomial with fixed coefficients. The polynomial for each air tube 12 varies only by a simple gain factor. Thus, according to the currently preferred embodiment, the response of any air tube can be calibrated to replicate an ideal response or model by simply multiplying the air tube response by a constant. Since the pressure output curve versus air flow feed for each air tube 12 varies only by one constant, the measured pressure of an air tube 12 can be compensated to achieve an ideal pressure output, for any expense of Air flow determined between 0 and 16 liters per second. Although the present invention is described in a particular embodiment wherein calibration of each air tube can be performed by simple generation of a simple calibration constant for each direction of air flow (inspiration or expiration), the present invention is not limited to this exemplary mode. According to the currently preferred embodiment, after pressure measurements are obtained for air flow expenses in the direction of inspiration and the expiration direction for an air tube 12 present, these two pressure measurements are compared with two measurements of corresponding model pressure. The model pressure measurements are obtained by averaging pressure measurements from a large batch of initial sample of flow tubes 12 from the manufacturing line as is currently preferred. A gain factor is determined, based on the tube pressure measurement of the present air tube 12, and the tube model pressure measurements. For example, if the model pressure measurements for the direction of inspiration are slightly higher than the measurement of tube pressure present for the direction of inspiration, a correction factor is generated to increase the pressure measurement of the tube present 12 to the measurement of pressure model. This correction factor comprises a constant in the currently preferred mode. A search table that has a number of air-tube-present measurements 12 and corresponding correction factors can be used, as just one example. As currently incorporated, this search table may comprise a large number of tube pressure measurements present according to the desired precision and corresponding correction factors. The correction factors as they are currently incorporated, calibrate each tube present at a desired pressure level. Still further, in accordance with the currently preferred embodiment, a simple binary number is employed to represent both correction factors for any present air pipe 12. Since the present air pipe 12 is tested for a pressure measured both in the direction of inspiration as the direction of expiration, two different correction factors will be generated, corresponding to the two measured pressure ratios of the tube for present air 12. The simple binary number is currently preferred to represent these two correction factors in a compressed form, and they can also be obtained from a search table. Figures 14 and 15 illustrate perspective views of a spirometer design according to the currently preferred embodiment. The tube 212 is substantially covered by the housing and the display 94 and the transparent overlay button 112 are larger than in the previously described embodiments. This invention has been described with respect to various examples and specific modalities. Alternate modes may include different equipment, orientations, distances and tolerances as long as the information of the air pipes can be sent automatically. It will be understood that the invention is not limited thereto and that it can be practiced in a variety of ways within the scope of the following claims.

Claims (20)

1. CLAIMS 1. A spirometer adapted to support an air tube, the spirometer is characterized in that it comprises: a frame adapted to detachably hold an air tube that has tracking information; a character recognition unit adapted to automatically read the tracking information; and circuits adapted to determine if the air tube will be previously employed in the spirometer, by comparing the reading tracking information with at least one reference value.
2. 2. The spirometer according to claim 1, characterized in that the spirometer also comprises means for deactivating the spirometer before a determination by the circuits that the air tube has previously been used in the spirometer.
3. 3. The spirometer according to claim 1, characterized in that the spirometer also comprises means for activating a spirometer alarm on a determination by the circuits that the air tube has previously been used in the spirometer.
4. 4. The spirometer according to claim 1, characterized in that the spirometer also comprises a memory for storing the reference value at least.
5. The spirometer according to claim 4, characterized by at least one reference value comprising tracking information that was previously read from another tube for air, by the character recognition unit.
6. 6. The spirometer according to claim 4, characterized in that at least one reference value comprises a plurality of reference values, each of the plurality of reference values corresponds to tracking information that was previously read from an air tube individual by the character recognition unit.
7. The spirometer according to claim 1, characterized in that the frame is adapted to removably support an air tube having a pressure response and a machine-readable calibration information, referring to the pressure response of the tube for air; and the character recognition unit is adapted to automatically read the calibration information.
8. The spirometer according to claim 7, characterized in that the spirometer further comprises: a pressure sensing structure adapted to detect a pressure in the air tube is held by the frame and to provide pressure data based at least on part in the pressure in the air tube.
9. 9. The spirometer according to claim 8, characterized in that the circuits are adapted to automatically process the calibration information that is read by the character recognition unit, the circuits are adapted to use the reading calibration information to automatically correct the pressure response of the air tube that is supported by the frame to a pressure response of a model air tube, having a configuration and dimensions that are substantially similar to the air tube that is supported by the frame.
10. 10. A spirometer adapted to support an air tube, the spirometer is characterized in that it comprises: a frame adapted to removably support an air tube having a calibration and pressure response information with respect to the pressure response of the air tube; a pressure sensing structure adapted to detect pressure in the air tube supported by the frame and to provide pressure data based at least in part on the pressure in the air tube; a character recognition unit adapted to read the calibration information; a memory for storing the calibration information that is read by the character recognition unit; circuits adapted to process the calibration information that is read by the character recognition unit, the circuits are adapted to determine if the air tube has been previously used in the spirometer, by comparing the read calibration information with a reference value in the memory.
11. 11. The air tube according to claim 10, characterized in that the circuits are further adapted to use the read calibration information to correct the pressure response of the air tube supported by the frame to a pressure response of a tube for model air that has dimensions that are substantially similar to the air tube supported by the frame.
12. 12. The air tube according to claim 10, characterized in that the calibration information is machine readable.
13. The air tube according to claim 10, characterized in that the character recognition unit is adapted to automatically read the calibration information.
14. The air tube according to claim 10, characterized in that the air tube further comprises tracking information which is separate and distinct from the calibration information.
15. 15. An air tube having a pressure response adapted for use in a spirometer, the air tube is characterized in that it comprises: a tubular member; machine-readable calibration information adapted to automatically match the pressure response of the air tube with a model pressure response of a model air tube having dimensions substantially similar to the air tube; and machine-readable tracking information arranged on the outer surface of the air tube to automatically match the tracking information, providing a unique identification of the air tube compared to other air tubes.
16. 16. The air tube according to claim 15, characterized in that the air tube further comprises machine-readable calibration information adapted to automatically relate a pressure response of the tube for air, with a pressure response model of a tube for model air that has dimensions substantially similar to the air tube.
17. 17. The air tube according to claim 16, characterized in that the machine-readable calibration information excludes alpha-numeric text.
18. 18. The air tube according to claim 15, characterized in that the calibration information comprises a bar code format.
19. 19. The air tube according to claim 15, characterized in that the air tube is disposable.
20. 20. The air tube according to claim 15, characterized in that the air tube is biodegradable.