DE3428873A1 - Heart/lung testing device - Google Patents

Abstract

The invention relates to a heart/lung testing device having a mouthpiece for the patient and a device for generating a signal that is proportional to the inhaled and exhaled flow, a CO2 analyser and an O2 analyser for the exhaled flow, which likewise generate signals, and a waveform analyser which has a computer and means for scanning the electrical signals in a predetermined sequence and for converting from these into digital form, as well as a device for at least temporary storage of the digital variables for use in arithmetic operations, a display for the results being provided which is controlled by a further computer to which the results of the first computer are transmitted.

Description

Medical Graphic Corporation, 5o1 West County Road, E, Shoreview, MN / USA

Herz-Lun οΎΊΓ ^ ΎΤΊϊΎ establishment

The invention relates to an electronic cardiopulmonary testing device that works directly and breath after breath works to improve the performance of the heart and lungs when beans are breached. to estimate. ~ ...

In the case of known monitoring devices, an analysis could be carried out Breath after breath of heart and lungs of a patient can not be realized on exercise.

The oldest monitoring devices involved exhaling or exhaling the patient into a bag, such as a Douglas bag or a weather balloon, for manual collection of exhaled gases. At the end of an exposure period, a gas analyzer was then used to analyze the gases in the bag to determine the CO ₂ and O ₀ exhaled. The exhaled volume was also determined by placing the contents of the bag in a gasometer (Tissot) and quantifying the volume of gas exhaled during the collection period. Starting from this data, numerous numerical calculations to be carried out by hand were necessary in order to determine some of the possible cardiopulmonary parameters.

Another known testing device consists of one Mixing chamber that is used to collect exhaled breath from a patient, which is passed through a Gas analyzer is checked at periodic intervals to get an average value related to the exhaled gas concentration determine. The exhaled volume is determined either by the bag method described above or by another

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^^ volume-changing device, such as a turbine, measured.

None of the known institutions perform breath-by-breath analysis

- to record the important first exhalations during an exercise period. The known devices are also not able to account for specific minute intervals, which are typically present in disability and rehabilitation assessments. A basic type of standard verification of the behavior and the parameters of the heart and lungs is therefore not yet available.

The cardiopulmonary testing device according to the invention is one such allows simultaneous processing and analyzes each breath starting with the first and progressing over a specified time interval as well as monitoring an individual both at rest and under stress.

The invention relates to a heart-lung test device with a

'i5 microprocessor based waveform analyzer for performing analysis of the An individual's cardiopulmonary activity at rest or, more importantly, in a stress period, breath after breath in real time to measure a Variety of parameters. The facility can be used to diagnose an organic heart or lung problem, or a general physical one To check an individual's constitution. The device is a diagnostic system accessible to the user, which has an output a basic metabolic function of an individual on a basis Breath by breath or over a user-specified time interval, starting with the first breath and continuing for as long as the individual is in a stressful situation or is being monitored during a state of rest.

According to a preferred embodiment, a microprocessor-based waveform analyzer is provided which receives as inputs the outputs of cardiopulmonary transducers in order to provide a real-time analysis, breath by breath, of the cardiopulmonary parameters of an individual. For example, the inputs can be a pneumatic tachograph or an O _{2 analyzer.} a (^ analyzer, an EKG monitor and, if desired, a cycle ergometer, a treadmill, other types of cardiac stressors, and an ear oximeter. The waveform analyzer, under computer control, samples and converts the analog signals from the transducer to digital signals while

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at the same time a possible phase shift of the signals is compensated.

..- ■ '"' and saves them for subsequent calculations- The waveform analyzer transmits digital data that define the heart-lung parameters of an individual, for recording on tape or disk or for graphical display on a screen and to a hard disk. iopy printer under the control of an auxiliary computer. Such parameters as the respiratory volume, minute air supply, breathing rate, heart rate, inhalation time of the last breath, total time of a previous breath, minimum of CCL and O ₂ , peak of CO ₂ and O ₂ and volume of CO ₂ and O ₂ can be stored, displayed or recorded. The device provides real-time monitoring of a patient while under stress until the anaerobic threshold is reached. When stress is relieved, the recovery of cardiopulmonary functions can be observed By making the inspection on a breath-by-breath basis, unnec Necessary patient stress and hazards are eliminated, which becomes important when the patient undergoes cardiac or pulmonary rehabilitation.

The checking can ir, for example, a hundred times per second; each dynamic channel to thereby provide a relatively "continuous update of the information that is being processed by the waveform analyzer." The waveform analyzer ν is not only controlled in such a way that it only takes into account every breath, but also detects inconsistent breathing behavior, for example as a result of coughing, swallowing, etc.

Another essential feature of the invention is provision of means by which fitness problems or organic heart and lung diseases are diagnosed and during treatment and Rehabilitation program can be monitored. The facility includes suitable electronic means for providing a momentary display the cardiopulmonary parameters of an individual in either a graphical display or tabular data format on a breath basis Breath. The printed output can later be used to encourage reimbursement of medical expenses, whether that be the Reimbursement through an insurance company or a government orogram.

Another important aspect of the invention is the practice of Stress tests. For this purpose, the patient can use a cycle ergometer, a

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. ^: '' Treadmill or some other device to do work, during which work certain metabolic parameters, such as an anaerobic threshold, can be determined. Here, the patient can be prevented from exceeding a predetermined safety threshold. This is particularly important for those individuals who are being diagnosed with medical conditions while avoiding unnecessary patient stress and discomfort, especially in those cases where exercise involves a. Could pose a risk to the patient.

Another important aspect of the invention is a breath-to-breath gas exchange analysis for exercise testing in a clinical setting that enables rapid, step-by-step exercise testing. Complete information about a patient's anaerobic parameters can be obtained
can be obtained using an incremental or progressive exercise study. These types of rapidly progressing exercise tests result in minimal patient fatigue and rapid recovery following exercise completion. This is beneficial because repeated tests can then be used to assess the effect of a medicine or oxygen treatment on body response to exercise.

The object of the invention is to mainly .cn a To create cardiopulmonary testing equipment that provides a real-time breath-by-breath analysis to monitor an individual to determine whether the individual is now in Is at rest or in a state of stress.

The test device according to the invention is flexible in clinical use, provides safety and comfort for the patient, increased resolution

and accuracy in the measurement of maximum oxygen uptake (VO ₂ max), the ability to measure the kinetics of the OP uptake of the (XL output and air supply during exercise, the ability to measure and determine the tendency of end breathing gas volume values throughout the exercise test and also the time of execution, playback and recording via hard copy

to reduce an overtest. ^:

The invention also offers the advantage of using a plurality of data processing devices that operate on a coordinated basis work according to a specific distribution of tasks between the data processors. In particular, a first data processor is used to scan the control various metabolic parameters, the sampled values in Bringing digital representation and various invoices using the

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To carry out digital data. A second data processor is related used with the print-plot and display facility to the user Deliver meaningful data.

. The waveform analyzer, which is provided for sampling a variety of analog input parameters, comprises circuitry for converting the analog signals to digital signals and for correctly arranging the phase shift of the dynamic signals belonging to the O ₂ and C0 ₂ concentration, sö ~ that these are precisely timed so that they are interrelated with the current. This means that the waveform analyzer also includes circuitry for digitizing the inhalation and exhalation flows which stores and stores these signals

- Corrected with regard to the phase lag between the exhalation flow _{signals and the O 2} and C0 ₂ signals.

..-. The test device according to the invention provides a real-time display or a real-time plot on the basis of breath by breath of a large number of parameters, including the respiratory volume, respiratory rate, exhalation ventilation, oxygen and C0 ₂ partial pressure at the end of inhalation, _{O 2} uptake, C0 ₂ release , Breathing quotient, venting equivalent for oxygen and CO ₂ , heart rate, oxygen pulse and oxygen saturation. These parameters are only given as examples.

Further refinements of the invention can be found in the following description and the claims.

The invention is illustrated below with reference to the accompanying figures an exemplary embodiment explained in more detail.

FIG. 1 shows a perspective view of a preferred one Embodiment of a heart-lung testing device.

FIG. 2 shows a block diagram of the cardiopulmonary tester FIG. 3 shows a schematic block diagram of a waveform analyzer as used in the test device of FIGS is used.

FIG. 4 shows representative waveform inputs for Waveform analyzer of Fig. 3.

FIG. Figures 5a through 5i show flow charts for the waveform analyzer Microprocessor base of Figs. 2 and 3.

FIG. Figure 6 shows a representative printout of the cardiopulmonary tester.

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According to FIGS. 1 and 2, the heart-lung testing device 1o comprises a Frame 12 containing a plurality of modules including a pneumatic tachograph 14 coupled to a mouthpiece 16. Adjacent to the mouthpiece 16 is a differential pressure transducer 18 and an associated carrier / demodulator amplifier 2o arranged ^ which are used to a analog electrical signal proportional to the gas flow during inhalation and ^ exhalation to deliver. Pneumatic tachographs are commercial available so that their structural details do not have to be explained. Between the mouthpiece 16 and an oxygen (Op) analyzer 24 and A carbon dioxide (COp) analyzer 26 is arranged with tubes 22.

An EKG monitor recorder 28 with a screen display 28a and a Strip recorders 28b provide the EKG output for an individual. A waveform analyzer 3o is connected to the pneumatic tachograph 14, the EKG monitor recorder 28, the oxygen analyzer 24 and the Carbon dioxide analyzer 26 connected. The waveform analyzer 3o can also with a cycle ergometer 32, a treadmill 34, an ear oximeter 36 and be connected to a cardiac stress system 38. Components 24 through 38 are known and available and in the manner described below with the Waveform analyzer 3o connected. Another frame includes a central one Computer unit 4o, a cathode ray current display 42, a teletype transceiver keyboard 44, a graphics copier 48, a Belt drive and possibly a plate 52, which are shown schematically in FIG is shown.

The inhalation and exhalation tubes 22, the mouthpiece assembly 16 and the transport hoses for the oxygen analyzer 24 and the Carbon dioxide analyzer 26 are carried by a spring-loaded two-legged articulation of the frame 12, so that the test person can hold the mouthpiece comfortably in the mouth, the weight of the other parts being borne by the articulation. -The test device 1o allows one precise, precise measurement, breath after breath, of respiratory and cardiac functions ■ in addition to checking the exhaled gas.

In the block diagram of FIG. 2, the relative connections of the various components 14 to 52 are shown. The waveform analyzer, which is shown schematically in Fig. 3, has a plurality of serial input-output channels for the input and output devices 14 to 38. The waveform analyzer 3o is connected to a computer 4o.

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- The pressure transducer 18 (Fig. 2) is used to convert äer differential pressures obtained during inhalation and exhalation through the mouthpiece 16, into electrical signals that are directly proportional to the breathing gas flow. This electrical signal is applied to a first input channel (CH 1) of the waveform analyzer 3o.

A test tube (not shown) connects the mouthpiece 16 to the

Inputs of a carbon dioxide analyzer 26. This is used to measure the concentration of carbon dioxide in an exhalation _{gas mixture using infrared absorption. However, other types of devices for measuring the partial pressure of CO 2} in a gas mixture can also be used

The output from analyzer 26 is an electrical analog waveform according to the real-time CCL concentration during the monitored Respiratory cycles. This electrical signal is applied to a second input channel of the waveform analyzer 3o.

In the same way, exhaled gas from the mouthpiece 16 is into the Inlet opening of a CL analyzer 24 out, which is also a provides an electrical signal that is a measure of the partial pressure of oxygen is in the gas mixture being tested. This electrical signal is applied to a third input channel of the waveform analyzer 3o.

As shown in Fig. 3, the waveform analyzer 3c is preferable a microprocessor based device for analyzing analog waveforms programmed to use received waveforms to a predetermined standard so that those waves that do not conform to the standard from further processing be eliminated. In this regard, the waveform analyzer 3o can be capable be able to measure and store the peaks of a received values Waveform and frequencies of the incoming signals. Furthermore, precautions have been taken to enable the waveform analyzer 3o by control an external device such as an auxiliary computer, which may be a general purpose digital computer. The waveform analyzer 3o is provided with a serial interface 8o. By using a microprocessor control in the waveform analyzer 3o it is possible to obtain the Unit to "program, with a multitude" of inputs analyzed and special work on the data can be performed in a desired order.

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There are four analog waveforms that are typically applied to channels 1 through 4 of waveform analyzer 3o that are proportional to gas flow, carbon dioxide and oxygen levels in the exhaled gas mixture, and heart rate, respectively. The heart rate signal is usually obtained from the EKG monitor 28 and fed to the channel 4 of the waveform analyzer 3o. Based on these input signals, in addition to others as intended, waveform analyzer 3o processed the received data to provide such parameters as final tidal volume, ventilation, inhalation time of last breath, total time of last breath, respiratory rate, etc. As a result of the use of the analog waveform from the carbon dioxide analyzer 26, the waveform analyzer 30 can be programmed to calculate the CCL peak value, baseline value, as well as the volume of CO ₂ exhaled on the last breath. Correspondingly, the analog signal obtained from the oxygen analyzer 24 can be processed in the waveform analyzer 3o to provide values indicative of the peak value of Op, the base value for O ₂ and the volume of O ₂ at previous breathing process was exhaled. The heart rate signal that is given on channel 4 of the waveform analyzer 3o is only the heart rate, which is measured in beats per unit of time.

The serial digital data from waveform analyzer 3o can be via a serial interface can be given to the computer 4o, which is programmed to carry out various calculations relating to the received data. The computer 4o can, for example, the ventilation value in Calculate liters per minute and present the calculated result on a Vidio display terminal 42 or a printer / plotter. Additionally the computer 4o can be programmed to display an instantaneous display on the Screen 42 to provide a series of text instructions so that the Device can be accurately calibrated and used. That is, the video display 42 can also present a sequential display of levels, which are to be carried out during the initial calibrations and the later test functions. The computer and the display option therefore make the facility "interactive" so that the need for highly skilled operators is reduced.

The waveform analyzer 3o comprises an analog input multiplexer 54, which has a large number of input channels, for example CH 1 to CH 8, with which the gas flow meters 14, 18 and 2o, the gas analyzers 24 and

26 and the EKG monitor 28 are connected. The multiplexer 54 ..works in the usual way to have one of the channels at a time with one

- \ 'output line 56 to be individually "coupled depending on the signals, to the selector inputs 58 of the multiplexer 54 from its internal Microprocessor can be applied. The output line 56 is at an input an analog / digital converter 6o connected, which has a pattern or a word in binary code. on the parallel output lines 62, the indicative for that placed at its entrance. Analog signal is.

The output from the analog / digital converter 6o is connected to an input register 64 of a bus-structured microprocessor 66 coupled. The microprocessor 66 includes a data bus 68 and a control bus 7o along with one arithmetic module 72, a control module 74 and a control module 76. Each the module receives control signals over control bus 114 and transmits or receives operand information over data bus 7o. Therefore, information from The input register 64 is transferred via the data bus 68 to the memory 76 under the control of the control module 74. Alternatively, data can be shared between the Memory module 76 and the arithmetic module 72 are transferred via the data bus 68.

Data from the memory 76, the arithmetic unit 72 or the control module 74 can also be sent to an output register 78 via the data bus 68 be transmitted. Where serial data transfer is desired, the individual levels of output register 78 can be set to one Parallel / serial converter are given, which is in the serial interface 8o is included, the serial output of which can be clocked out on line 82 at a rate determined by control signals transmitted via the Control bus can be given to the clock input 84 of the serial interface 8o. The data from the waveform analyzer 3o after completion can be used for each breath or by specifying a time interval selected by the user up to 6o seconds on the auxiliary computer 6o, the is used to provide a screen display 42 or hard copy printer / printer device 44 as shown in FIG steer.

The mode of operation of the heart-lung testing device 1o is described below in Connection with FIG. 4 is described.

FiQ- 4 shows representative waveform inputs for the The waveform analyzer of Figures 1 through 3. Here are the four

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^ Input analog signals from the carrier / demodulator 2o connected to the pneumatic tachograph 14 is connected, the CC ^ analyzer 26, des Op analyzer 24 and the EKG monitor 28 shown. The three dynamic ones Channels allow sampling to occur at a rate of about 100 sample points per second per channel.

The mouthpiece 16 of the person to be examined is in operation, which is either at rest or under stress, in their mouth for real-time analysis breath by breath. Before operation, the tachograph 14, the analyzers 24 and 26 and the EKG 28 were initially calibrated and set.

The signal that appears at the output of the carrier / demodulator amplifier 2o during any one of the many sampling periods appears is shown as waveform "A" which represents the instantaneous gas flow of the patient's breathing system, measured in milliliters per minute. It can be seen that the gas flow waveform is for the most part quite rhythmic, however becomes somewhat uneven in the section indicated by the vertical dashed lines before the rhythmic course is regained. The irregular one Section of the curve may be due to a cough or swallowing or the like occur.

As will be explained later, the waveform analyzer eliminates 3o from the various measurements to be plotted data that are recorded on a irregular section of the breathing airflow would be based. The waveform analyzer 3o can detect frequency variations of a received signal from determine a norm and generate a lock condition, thereby making calculations on data obtained until the lock situation is removed, be excluded.

To calculate the ventilation in milliliters per minute, the area under the gas flow waveform k, which is dashed, is integrated. On the basis of breath by breath, the product of the respiratory frequency and 'the volume for this provides minute ventilation measured in liters per minute. However, if each of these volumes are added up over a predetermined, user selected time interval, the result is the average ventilation over a number of breaths. The checker 10 operates so that data remains current. When a new breath is taken, a rate counter is incremented and the measured component corresponds to the

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- ■■ "is to be assigned to the oldest breath, which is now outside of the user selected time inter va-H-s-1 -lays, - is dropped.

The manner in which the analog gas flow signal is processed to obtain the desired information content therefrom is as follows

explained. _

The exhalation time T _£ comprises the positive half-wave period of a tachograph signal (waveform-A), while the total time Tj ₀₁ - is equal to the full wave time of the previous breath. The tidal volume Vj is equal to the integrated value of the exhalation half cycle of the previous breath and represented by the hatched area of waveform A. Using this variable, the ventilation is measured milliliters per minute and represented by the symbol V _£ das' / oleum multiplied by the respiratory rate above the last breathing process and can be expressed by the following equation:

(TV ₁ + TV + ... + TV J

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(TT ₁ + TT ₂ + ... + TT _n )

where (TT ₁ + TT ₂ + ... + TT) is greater than or equal to the time interval selected by the user, where TT _{1 is} the oldest time and TT is the newest time.

The waveform analyzer 3o eliminates these calculations irregular samples representative of abnormal breathing spaces. In particular, it must be for a given breath that is considered valid should be, the tidal volume Vj or the total exhaled volume for this given breath will provide a minimum value for Vj, Jer through the Operator is fixed as a constant. If the total time totals exceed the time interval selected by the user, the volume and the Time for oldest breath taken out of calculations and last volume and time taken in. In this way, the Data sampled by the waveform analyzer 3o and used to determine the Ventilation factor V ^ used, kept up to date. -

In order to obtain the desired CO ₂ and respiratory concentration, the waveform analyzer processes the signal output from OL analyzer 26 by summing the peak values of the pulses (waveform B) over the same from

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User selected time interval. By multiplying the

With the phase-aligned instantaneous gas flow and instantaneous CCL concentration, an integrated weighted average representing the exhaled CO ₂ volume (VCO ₂ ) can be obtained.

Similarly, the waveform analyzer treats the O ₂ signal, ^ "waveform C, by summing the peak values of the wave over the time interval selected by the user O ₂ volume (VO ₂ ). After receiving a suitable control signal from the auxiliary computer 4o, the waveform analyzer 3o will scan the input channels 1 to 4 sequentially in order to obtain the information regarding gas flow, COp, O ₂ and -'- "' In addition, information from a cycle ergometer, ear oximeter, etc. can optionally be received via the channels δ to 8. During the transmission and conversion processes, the processor in the waveform analyzer 3o can simultaneously make calculations on previously received data, so that on this way calculations and data transfers overlap e can be made. Data that flow to and from the auxiliary computer 4o are preferably encoded in a 7-bit ASCII code, with transmission rates of 240 baud being able to be used, which is compatible with known communication agreements for digital transmission systems.

The waveform analyzer 3o used in the test equipment 1o , includes a microprocessor programmed to perform a variety of functions as set out below with the aid of the flow charts of FIGS. 5a to 5i will be explained.

Fig. 5a shows a flow diagram for the operations performed after the power is turned on. The microprocessor of the Waveform analyzer 3o is operated intermittently and following the The RAM memory of the Microprocessor cleared (block 150) and all address counters and stack pointers started (block 152). Then the microprocessor causes that certain conversion constants that are activated via manually operated DIP switches entered into memory under program control (block 154). According to block 156, the communication algorithm, USART, is implemented in a Manner known to those familiar with the Intel 8o85

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- are familiar with the microprocessor. The facility then enters the Execution stream and "waits for the first interruption, whereupon one of the different processing modes can be set in motion. This is represented by block 158 in Figure 5a. Decision block 16o provides the Means by which the microprocessor can determine if there are any tasks --- waiting to be processed. If so, the handle Microprocessor this aof FIFO basis, as indicated by block 162.

After the oldest task has been completed, control returns to the entry point XI, and if there are no more tasks waiting, the execution is in an idle state awaiting the next interrupt.

Data from the various sensors 14, 24, 26 and 28 of FIG

into the waveform analyzer under control by the so-called "G command" .transferred. The flow chart relating to the G command is in Figure 5b When the waveform analyzer receives the G command from the computer, this causes the microprocessor of the waveform analyzer to collect all of the data from a previous command (block 164) and the analog multiplexer 54 of the analog-to-digital converter of FIG through 4 at a rate of about 100 per second (block 166). The following are the parameters of total time (TT) and respiratory volume (TV) for calculating ventilation response (VE) and breathing frequency (f) deleted from a previous iteration. This is indicated by block 168 in Fig. 5b. Next, the clock is initiated in such a way that interrupt signals of the update mode with approximately Outputs 3oo samples per second and increments each active channel from its previous result with the same hundred samples per second is brought up to date. Control is then passed back to the system execution at entry point XI at block 17o. The G command will again have a. Interruption started every millisecond occurs, the entry point being at G2 in the flow chart of Figure 5c.

Figure 5c shows that following entry the system clock is reset to be able to handle a subsequent interrupt to recieve. Also the analog multiplexer 54 and the analog / digital converter 6o are set to begin converting the data received from the active channels 1 to 4. These operations are performed by the Blocks 172 and 174, respectively. As described above, channel 1 is designed to have gas flow information about the tachograph 14 through the

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Carrier / demodulator amplifier 2o receives. Channel 2 receives data from ,., - '. "' CCL analyzer 26, while channel 3 data related to the Oxygen concentration from (k analyzer 24 picks up. Channel 4 receives Heart rate data from EKG 28.

Assuming that channel 1 is active so that the gas flow information is to be updated, as indicated by block 176, a gas flow conversion program is controlled which is shown in the flow charts of FIG. 5d and 5e is shown.

Fig. 5d shows that the control at the point labeled "GF" and Enters at decision block 178 where a determination is made whether the current date from the tachograph 14 is representative of the Is the inhalation part of a full respiratory cycle. If the waveform is negative, indicating inspiratory flow, the system will follow "Yes" exit from block 178 and it is determined whether the previous Sampling point on channel 1 was an indicator of the inspiratory flow at block 18o. If so, control loops to entry point GF is returned and this sampling continues until the sample becomes positive, indicating that an exhalation half cycle has begun Has. If this occurs, control exits decision block 178 via the "no" route and, as represented by block 182, becomes the current one The reading added to the exhaled tidal volume (TV) for that breath. Next, at decision block 184, a test is made carried out whether the previous reading was negative. Assuming that this was the F ^ II then it becomes the current real time of the microprocessor stored to later indicate the end of the inhalation time, this is done by block 186. If the previous reading on channel 1 was still positive, this is indicative that the exhalation half-cycle is not yet completed and the individual is still exhaling with the operations of blocks 188 and 19o provide a feedback path to the entry point of the Decision blocks 178 include. Following the exit of block 186, block 192 in the flow chart of FIG. 5d then initiates that the clock is reset to show the start time of the next breath.

Next, start the exhalation portion of the cycle with a compared to predetermined constant that is in the system through dip switches on the front wall of the waveform analyzer 3o. If the Exhalation time is less than the available time, this will be considered invalid

"Breath determined and the data belonging to this interval discarded. This ..Operations are represented by decision blocks 194 and 196, where

- "" the output of the latter is harvested-driven to the algorithm for the Re-initiate gas flow to bring it up to date by entering the GF. As stated earlier, an invalid breath can occur due to a cough or other breathing disorder. The inventive The system is therefore able to cope with such irregular sampling intervals discriminate so that they cannot lead to the processing of misleading data.

Assuming that the exhalation time interval is indicative of a valid breath, a flag is set indicative of the completion of the exhalation cycle, which flag is used by the CO ₂ and _{O 2} analysis programs, as will be described later . The setting of this flag is represented by block 198. The microprocessor in the waveform analyzer then subtracts the exhalation time from the total time to obtain the inhalation time IT for the breath (block 2oo).

The explanation of the flow chart of Figure 5d continued to this point assumes that the exhalation cycle has been sampled. At the onset of an inhalation cycle, control exits the decision block no path 18o and operation 2o2 is performed, with the current cycle time being recorded as the end of the exhalation cycle. The way in which this Information part is used will now be described in detail.

As shown by block 2o4, the system clock is reset to reflect the start of the exhalation time. It is again determined at decision block 2o6 whether the previous exhalation time was greater than or equal to 0.2 seconds. If not, that breath sample is discarded as invalid and control returns to entry point GF of block 178. Reference is made to blocks 2o8 and 21o of Figure 5d. However, if the test criteria for decision block 2o6 have been passed, the "inhalation active" flag is set and the CO ₂ and O ₂ algorithms are started. This operation is represented by block 212 of Figure 5d.

According to block 214, the microprocessor in the waveform analyzer 3o integrates the gas flow curve over the exhalation time interval to form the tidal volume (TV) factor. At decision block 216,

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determines "whether the exhaled volume is greater than or equal to the preset tidal volume limit is lower, and if not, the scan is invalid rejected as a "shallow" breath and the calculated value is not used to update the frequency and ventilation factors. Instead, control returns to the beginning of the algorithm Bringing back the gas flow, as by blocks 218 and 22o is shown. However, if the exhaled volume is greater than or is equal to the preset lower "limit, the sampled breath is valid and at the beginning of the inhalation cycle control returns to Entry point of decision block 178.

Figure 5e shows the flowchart that "ensures the operations following the completion of the operation represented by block 2oo in Figure 5d. When a breath sample is completed, memory buffering is allocated as shown by block 222, and that of First, breath identification data indicative of a shallow breath or a valid breath is entered into the transmission buffer, as is the inhalation time, total time and respiratory factors, which operations are performed by block 224 In the case of a short breath, test block 226 directs control so that the associated data is not transmitted, but instead the same buffer area is _{reserved for later use by the CO 2} and Op scanning programs what is shown by blocks 228 and 23o in Fig. 5e is tellt.

Assume that the breath sample meets the intended criteria decision block 226 directs control so that the next operation, represented by block 232, will take place. That that is, a new breath rate value is calculated by multiplying the Number of total time samples (TT) used by 6o and dividing that product by the sum of the total times of breaths taken in at a time interval selected by the user. In mathematical terms, this is:

6o χ Ν
F =

₁ + TT ₂ + ... + TT _n

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In this formula, DD is. the total time of the oldest breath in the sampling interval and TT the newest or most current total time of a breath.

After this calculated value in the selected transmission buffer is stored, the next operation of the waveform analyzer microprocessor is to compute ventilation, as by block 234 is shown in Fig. 5e. The calculated value is also included in the Transmission buffer stored at a desired location so that after transmission to the receiving computer, the latter will store the date at the location as the Properly recognizes ventilation parameters.

Following the operation described above, the

Waveform analyzer in connection with block 23o a flag that indicates that the gas flow update operation is complete and that control is passed to block 176 in Fig. 5c can return. These stages are through blocks 236 and 238 in that Flow chart shown in Fig. 5e.

When control is returned to the G-mode program for updating the processor, the next step shown by block 24o in FIG. 5c. This block directs control to the update program with respect to COp according to the flow charts of FIGS. 5f and 5g.

The first step that is performed is by block 242 in Figure 5f and consists in a comparison between the current amplitude sample at the output of the analyzer 26 with the minimum amplitude from this device for the breath in question. When this reading is less than the previous minimum reading, the new reading is stored as the new minimum value, block 244. If the value indicated by block 246 If the test shown reveals that the current reading exceeds a previous minimum value, a subsequent test is made in the decision block 248 to determine if it is negative, which is indicative of the inspiratory portion of an individual's breathing cycle. If it isn't Inhalation is involved, control becomes the entry point of Biock 242 as shown by block 25o in Figure 5f. This continues until the test at decision block 248 reveals that the Patient has started the exhalation cycle, at this point, after allowing the phase lag, the reading in channel 2 starts with the current one

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Expiratory flow, which corresponds to this time, multiplied and integrated is, block 252. The phase revision itself is introduced by providing a preset counter that is decremented at a fixed rate (Block 249a), a test being made at each iteration to determine whether the prescribed period of time has passed (Block 249). After that, the current CCL value at the time of sampling with the maximum reading of the COo value during the exhalation cycle of the breath in update block 254 compared. Next, that is made by decision block 256

• Performed the test shown, determining whether the ■ current COp reading is a new spike. If so, this current reading is considered indicative of. saved the peak value for CO ₂ for the breath in question. This operation is represented by block 258 in Figure 5f.

If, or if the current C0 ₂ does not spike and this spike reading is stored, proceed to decision block 26o in Figure 5g. A test is carried out here to determine whether the expiratory flow has ended. If not, the entry point of block 242 in FIG. 5f is returned, as illustrated by operation 262. Assuming that the exhalation cycle has ended, the microprocessor of the waveform analyzer calculates the volume of CO ₂ during the exhalation cycle. The resulting parameter is saved and comprises the weighted mean value of the exhaled CO ₂ volume. Since this is an electronically stored parameter, there is no need for a holding chamber to hold back the exhaled gas samples for later batch analysis, as is necessary in the prior art. These operations are represented by block 264 in Figure 5g.

If the results of the tests in decision blocks 246 and 256 were negative such that the minimum and peak values for CO _{2 were} not previously stored, then as represented by block 266, those values are not stored. The C0 ₂ parameters for that particular breath are then completed and the various timers and previously calculated values in the operational registers are caused to be cleared so that the system is ready to sample the next following breath. These operations are represented by block 268 in Figure 5g. Thereafter, return to block 242 in Figure 5f for the start of the CO _{2 update sequence.}

- YES-

.The G-mode update algorithm according to Fig. 5c, which _{follows after completion of the sequence for CO 2} , leads to return

- ■ "'" to the operation represented by block 27o for

Bringing up-to-date with O ₂ . The sequence represented by the flow charts 5h and 5i is actuated by the block 27o. In this sequence, a comparison is first carried out by block 272 between the instantaneous 0 ₂ amplitude on channel 3 and the maximum reading that is required for this particular
Breath was obtained. Decision block 274 determines whether the current sample exceeds a previous sample, and if so, then block 276 stores _{the current reading as the new peak value for O 2.} Following this operation, or immediately after determining that the new sample is not a peak, the signal on channel 1 is re-sampled to determine whether it is positive, ie, indicative of an exhalation cycle. This test is represented by decision block 278 in Figure 5h. If the test is negative, a jump is made back to the original comparator stage 272 in accordance with block 279b. If an exhalation cycle is occurring and the phase lag has been taken into account, the current amplitude reading on channel 3 is multiplied and integrated by the instantaneous expiratory flow corresponding to that time for that breath, as represented by block 28o.

If the phase lag is not detected at block 279, then the Phase lag is decremented by block 279a which loops back to block 279b.

According to FIG. 5h, the current reading from the 0 ₂ channel is compared with the

Compare the minimum reading for O _{2 obtained} during the exhalation time, block 282. Block 284 symbolizes the steps to be taken as a result of this comparison. If the current reading of channel 3 is less than any previous reading taken during the same breath interval, this is considered as the new minimum value and stored and later compared with a new reading of a subsequent cycle.

Following the storage step, it proceeds to flowchart entry point G02 of FIG. 5i. In decision block 288 it is decided whether the exhalation cycle is complete, and if not, a loop is made back to the entry point GO at block 272 in FIG. 5h. However, when the exhalation flow is complete, the next step is _{to calculate the volume of O 2} that has been exhaled by integrating the products obtained in block 2oo over the exhalation cycle, thus determining the need for a

Mixing chamber is mitigated. The resulting parameter is the weighted mean value of the CL volume and the various operations mentioned are represented by block 29o. If the maximum value for O ₂ and the peak value for this were not previously stored, as indicated by operations 276 and 286, these values will now be is stored in block 292, thereby completing the Op analysis for that particular breath.

-— At this point in time, various timers and counters are used used in the procedure, deleted or otherwise prepared to repeat the same functions on subsequent breaths. This operation is represented by block 294 in Figure 5i. After completing this step, one returns to block 27o in FIG. 5c.

If none of the indicators GF, GC or GO are active, according to Fig.

5c the heart rate HR on channel 4 considered next. in the Decision block 296 determines whether only the HR flag indicates activity. If this is the only active channel that has a Up-to-date is required, another test by Block 298 to determine whether a second has passed since a data stream was last transmitted from waveform analyzer 3o to computer 4o became. If more than one second has passed since the last heart rate data was sent, the one symbolized by the block 3oo is shown Surgery performed so that a new heart rate value in beats per Minute is calculated and transmitted. Then a return is made to the task that was interrupted for the previous calculations and transfers perform.

If the interruption occurred earlier than a second after the previous heart rate information was transmitted, a return to the interrupted task takes place immediately without renewed calculation and transmission. This is through operation 3o2 in Figure 5c

. shown. Similarly, another test is done at 3o4 if test 296 indicates that other than HR flags are active to determine whether a breath is complete. If not, you return immediately to the interrupted task. However, when the breath is completed, the entire data string becomes for the particular one Breath, which was previously formatted, transmitted to the computer by block 3o6.

The test device 1o is accessible for 4o parameters for each breath and can save it. Some of these parameters are set by the user

-lh ·

entered and are marked with (u).

1. Speed or workload, i.e. treadmill or ergometer

2. Height or force (u), i.e. ergometer or treadmill

3. VE ATPS - (ambient atmosphere, temperature and pressure, saturated)

4. True CL _

5. True CO ₂

~~ 6th breathing rate

7. Heart rate

δ. 0 ₂ saturation

9. VE BTPS (body temperature, pressure, saturated)

- 1o. VT BTPS - respiratory volume in body conditions

11. VO ₂ -O ₂ recording

12. VC0 ₂ -C0 ₂ delivery

13. R-respiratory exchange ratio

14. O ₂ PUIs

15. VE / VC0 ₂

16. PO ₂ (u) -arterial O ₂

_{17.CO 2} (u) -arterial CO ₂ 18.pH (u)

19. Base surplus (u)

20. A-aP0 ₂

21. V _D / V _T

22. O ₂ / KG 23. VE / VO ₂

24. PET C0 ₂ partial pressure of the final breathing volume

25. Parameter - open

26. PET O ₂ - partial pressure of the final breathing volume O ₂

27.Systolic pressure (either user input or read by waveform analyzer)

28. Diastolic pressure (either user input or read through the waveform analyzer)

29. Relative time

30. Workload

31. VE STPD (standard temperature, pressure, dry)

32. VT / VC

33. METS

EPO COPY

. Vt-

..- ■ '''34 . Breathing time ", .-" ^ "35. Total time of the last breath

36. Respiratory Basrsttnre- Oy- ~

37. Respiratory baseline CO ₂
38. Variable VT / TI

39. Variable TI / I I ^ --— ■ -

4Oi interval number

The test facility — 10 accesses, calculates, and stores 22 Parameter, breath by breath, for subsequent plotting, as these dynamic values are the most important in relation to plotting. The plotting on a screen or printer can be set to a selected interval with minimum and maximum values or from zero to a predetermined value be limited

The dynamic values that can be plotted are as follows: 1.VT (respiratory volume)

2. t (seconds)

3. Workload (kpm)

4. VT / VC («)

5. VE (ventilation per minute)
6. True O ₂ (V0 ₂ / VE STPD)

7. True CO ₂ (VC0 ₂ / VE STPD)

8. SaO ₂ (O ₂ saturation %)

9. Vo ₂ (surgery consumption ml / min)

10. VCOpiCOp production ml / min)
11. Heart rate

12. R (respiratory exchange ratio)

13. O ₂ -PuIs / ml / bpm)

14. v "E / V0 ₂ (C0 ₂ ventilation equivalent)
- ~ 15. VE / V0 ₂ (0 ₂ - ventilation equivalent)

16. 0 ₂ / kg (ml O ₂ / kg / min)

17. Systolic pressure (mmHg)

18. Diastolic pressure (mmHg)

19. METS

20. PETO ₂ (final respiratory volume %)
21. PETCO ₂ (final breathing volume 3 »)

COPY

.- '22. Respiratory rate

. ^ < Fig. 6 shows an example of a printout in tabular form of the dynamic parameters of an individual - and - is representative of parameters measured during exercise. The following parameters are listed from left to right:

1. Relative time (depending on the time interval)

2. Respiratory volume

3. Breathing rate

4. Exhalation ventilation

5. 0 ₂ partial pressure in the final breathing volume

6. CL partial pressure in the final breathing volume

7. CCL recording

8. C0 ₂ release

9. Respiratory quotient (CO ₂ A) ₂ )
1o. Ventilation equivalent of O ₂

11. Ventilation equivalent CO ₂

12. Heart rate

13. O ₂ PUIs / heart rate

14. Ear oximeter

The waveform analyzer 3o enables the basic limit threshold for exhalation flow as shown by waveform A in FIG. 4 to be determined. This threshold value supplies the real-time analysis, breath by breath, of the individual parameters. The waveform analyzer 3o also stores the expiratory flow values incrementing and taking into account the phase lag of the C0 ₂ signal and the O ₂ signal represented by waveforms B and C in FIG. These three values together with the EKG of the waveform D from FIG. 4 supply the necessary input parameters for the waveform analyzer 3o, which carries out the calculations and forwards them to the computer 4o. The waveform analyzer provides the real-time analysis for each breath as shown in the flow charts of FIG.

The testing device 1o enables the non-central processing of the Signals through the use of a microprocessor based waveform analyzer 3o which converts the received analog signals into digital signals can be converted, while the display and printing functions are controlled by using an auxiliary computer. The test device 1o delivers

EPO COPY # 1

-24-

, -. also an instantaneous display of the individual's parameters after each Breath and before the neatist's breath.

The hoses for sampling and the gas flow measuring module 16 are movably arranged on an adjustable spring-loaded boom device. _:
The waveform analyzer 3o preferably comprises an LED display window 3oa for displaying the respiratory volume, the final values for CO ₂ and O ₂ and the

Heart rate.

An analog to digital converter that works with a gas flow volume meter

is connected, can be connected to the computer 4o,. during a 32-character A / N display can be connected to the waveform analyzer 3o.

While the computer 4o is described as being connected downstream of the test device 1o it can also be used to perform other numerical calculations, whether or not related to the device 1o, for the best

"" Achieve timeshare.

The test device 1o can also be used for other types of clinical applications besides those described. these can Include nutritional studies, heat requirement studies, etc.

The computer 4o, the keyboard 44 and the plotting printer can also be used in the frame 12 can be integrated, wherein the computer 4o can be arranged in the lower panel, while an upper panel for a Polybarbonate overlay keyboard can be provided instead of keyboard 44. A plotting printer can also be provided in the frame -12, whereby a single, one-piece frame for the test device 1o is made possible.

The testing device 1o monitors and analyzes the first Exercise breaths to assess metabolic responses to exercise, for example the increase in the cardiac output, which can be assigned to an increase in the stroke volume.

The test device 1o also switches off the phase delay of the analog signals of the input parameter signals on a real-time basis.

- blank page -

EPO COPY

Claims (6)

Medical Graphics Corporation, 5b1 West County Road E, Shoreview, MN / USA Claims 1. Heart-lung testing facility, characterized by a) a mouthpiece for placement in the mouth of an individual, the Mouthpiece means means for generating a first analog electrical signal proportional to the inhalation and exhalation gas flow of the individual 5 includes, b) a first gas analyzer, which is coupled to the mouthpiece, for Generating a second analog electrical signal proportional to the amount of carbon dioxide in the exhaled gas stream, c) a second gas analyzer, which is coupled to the mouthpiece, for Generate a third analog electrical signal proportional to Gern Oxygen content in the exhalation gas stream, d. a waveform analyzer comprising: ' 1) a first computer which is programmed to perform arithmetic * operations according to a stored instruction program * 15 to carry out, 2) a device controlled by the first computer, which is connected to the device for generating the first analog electrical signal and the first and second gas analyzer is connected to sample the first, second and third analog electrical signals in a predetermined sequence and in convert digital quantities that are representative of the analog signals during the sampling interval of each signal, 3) a device in the first computer for at least temporarily storing the digital variables as operands for the arithmetic operations, e) means for displaying the results of an arithmetic Operations, f) a second computer, separate from the first computer, which controls the display device, and g) means for transferring the results of animal arithmetic operations from the first computer to the second computer. EPO COPY 2. Heart-lung testing device according to claim 1, characterized by
..--- a) a device-for-generating a heart rate signal and b) means for coupling the heart rate signal to the Means for sampling in the waveform analyzer. 3. Heart-lung testing device according to claim 1 or 2, characterized in that means for applying further signals to the Waveform analyzers are provided that relate to the workload being carried out performed by the individual. 4. Heart-lung testing device according to one of claims 1 to 3, characterized indicated that the means for sampling operates at a rate at least one hundred times greater than the period of the inspiratory or Expiratory flow is. 5. Heart-lung testing device according to one of claims 1 to 4, characterized indicated that the results of arithmetic operations are transmitted to the calculator at a rate that would display an indication on the basis of Breath after breath allows. 6. Herz-Lunngen test device according to one of claims 1 to 5, characterized indicated that a means for comparing the digital quantity, the ^ y is representative of the first analog electrical signal, with a "20 predetermined reference quantity and to exclude the digital quantity as Operands when the digital quantity misses the reference quantity in comparison is provided. £ 0