TECHNICAL FIELD

[0001] The present disclosure generally relates to improving breathing response of a user. In particular, the present disclosure relates to evaluating the breathing response of the user.

BACKGROUND

[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.

[0003] Carbon dioxide (CO2) tolerance is an important characteristic of breathing for a person. A higher level of CO2 tolerance means a person is better able to handle a temporary increase in CO2 content of the blood. For instance, when the person breathes during an athletic performance, the person will not only inhale and more oxygen but more carbon dioxide is also produced as a byproduct of the higher oxygen consumption. If a person with very low CO2 tolerance starts doing a physical exercise, the person will very soon start hyperventilating as a neurological response to the rising CO ₂ levels of the blood. This neurological response is also called the respiratory drive. When a person with a high CO2 tolerance starts doing physical exercise, they can perform at a very high level without getting out of breath, and their breathing is still quite calm and controlled even as a lot of oxygen is consumed, and their blood contains a high level of CO2. The respiratory drive also plays a role in stress, anxiety and panic, which are common causes of hyperventilation. Breathholding training helps build up CO ₂ tolerance, allowing one to become more comfortable in demanding or stressful situations. Buteyko and Pranayama Yoga breathing exercises also help to improve the CO2 tolerance. Further, at high altitudes, barometric pressure is significantly lower than that at sea level. A high altitude, oxygen molecules are spread further apart, lowering the oxygen (O ₂ ) content of each breath one takes, which leads to signs of O ₂ depletion: lower oxygen saturation (SpO ₂ ) values and lower oxygen consumption. When doing altitude training, mountaineers prepare themselves for the harsh condition of climbing mountains while breathing air with a much lower oxygen content. Therefore, there is a need to measure the level of CO ₂ tolerance and O ₂ depletion tolerance of the person. [0004] A strong causal relationship exists between a breathing minute volume airflow and a CO ₂ level of the blood. That is, when the CO ₂ percentage of the blood goes up, the breathing minute volume will also increase as a result, and when the CO ₂ percentage of the blood is decreased, the breathing minute volume will also decrease as a result. The CO ₂ tolerance testing procedure explores the relationship between the CO ₂ percentage of the blood and the breathing minute volume of the person’s breathing. As CO ₂ has an important enabling/facilitator function, promoting the body’s oxygen distribution, according to the Bohr effect, the testing score for the CO ₂ tolerance test is a relevant indicator of the general health and fitness of the person doing the testing. Higher scores mean the person has a higher CO ₂ tolerance and is likely more healthy and more fit.

[0005] In some conventional CO ₂ tolerance testing procedures, an easy breath-hold duration is counted and the breath-hold is stopped when the person experiences a very slight feeling of air-hunger, or a maximum breath-hold duration is counted and the breath-hold is stopped when the person experiences a strong feeling of air-hunger to build up the CO ₂ tolerance. A longer easy or maximum breath-hold duration means that the person has a higher CO ₂ tolerance. In another breathing-based CO ₂ tolerance testing procedure, the person starts by taking 3 or 4 breaths, where an inhale followed by an exhale equals 1 breath. Then a maximally deep inhale is taken and once the person’s lungs are full, the exhale is performed as slowly as possible through a nose or a mouth. A timer is stopped when the person runs out of air, swallows, or feels that he/she must take the breath in. The time taken (in seconds) to empty the lungs is recorded to determine the CO ₂ tolerance.

[0006] However, both breath-hold and breathing-based CO ₂ tolerance procedures are prone to inaccuracies and errors, and the subjective experience and actual CO ₂ level of the blood or the inhaled or exhaled air of the person doing the test is not measured at all during these tests. Also, these conventional CO ₂ tolerance testing procedures provide test results in terms of duration in seconds of exhalation or breath-hold, which is not the ideal scoring format for a CO ₂ tolerance test. The CO ₂ tolerance test should ideally output an actual detailed CO ₂ percentage number as the main test result, with a high level of accuracy, where a higher CO ₂ percentage number means the test result is better.

[0007] Furthermore, mountaineers prepare themselves in various ways to climb a mountain, for example by sleeping in an altitude simulation tent with lower levels of oxygen in the air or by using a breathing mask to restrict airflow (as in patent document US9707444B1). A hypoxia altitude simulation test (HAST) evaluates how persons respond to breathing air with significantly reduced levels of oxygen and is commonly done for airline pilots or people with pulmonary disease, for example, chronic obstructive pulmonary disease (COPD). The test consists of providing the test subject with air with oxygen content of, for example, 15.1%, simulating a cabin air pressure of 8000 feet. The test may also be done by placing the test subject in a hypobaric pressure tank. The test may also be done with various oxygen concentrations, for example, changing the oxygen content to subsequently 20.9% (baseline), 17.1%, 15.1%, 13.9%, and then again 20.9% (recovery) while ventilatory and gas exchange variables are measured, and the test subject is monitored for potential symptoms or arrhythmias. The test may be repeated with supplemental oxygen as well to ensure not only adequate treatment of hypoxia but also reversal of any symptoms described during the test. If the test subject passes the test they would be allowed to travel by air without supplemental oxygen. If the test is partially failed, they may be allowed to only travel by air if they take supplemental oxygen with them, or when the test is completely failed, they may not be allowed to travel by air at all.

[0008] The HAST testing procedures aim to test the safety and fitness for air travel of the test subject. It is not designed to measure the O ₂ depletion response as an indicator of athletic performance and altitude training performance for athletes and mountaineers at very high levels of detail and accuracy. It does not provide athletes and mountaineers with valuable, detailed, and accurate data of the current status and historical development of their 02 depletion response, and does not provide detailed and accurate data to help athletes and mountaineers review their training methods to improve their 02 depletion response.

[0009] There is, therefore, a need in the art for an improved system that may be used to evaluate the breathing response of the person or a user by overcoming the deficiencies of the prior art(s).

SUMMARY

[0010] The present disclosure generally relates to evaluating the breathing response of a user. In particular, the present disclosure relates to evaluating the breathing response of the user to higher levels of carbon dioxide and lower levels of oxygen.

[0011] In a first aspect, the present disclosure provides a system to evaluate a breathing response of a user. The system includes an air-supply means adapted to provide a controllable air mixture to the user, where the air mixture includes at least oxygen and carbon dioxide, one or more sensors configured to measure one or more respiratory parameters of the user, and a controller communicably coupled with the air-supply means and the one or more sensors. The controller includes a processor and a memory communicably coupled with the processor. The controller is configured to receive, from the one or more sensors, at least one respiratory parameter of the user, and operate the air- supply means to gradually and continuously vary the air mixture, such that a content of at least one of oxygen and carbon dioxide in the air mixture changes significantly over a first duration of time. The controller is configured to receive, from the one or more sensors, the corresponding at least one respiratory parameter of the user at a plurality of time intervals over the first duration of time, as the at least one respiratory parameter changes in response to the gradually varying air mixture. The controller is configured to determine a correlation between the variation in a value of carbon dioxide or oxygen in the air mixture and a resulting change in the at least one respiratory parameter of the user, or an estimated maximum value of carbon dioxide or estimated minimum value of oxygen in the air mixture tolerable by the user, such that the corresponding value of the at least one respiratory parameter stays within a predefined range, or a maximum value of carbon dioxide or minimum value of oxygen in the air mixture, measured as the value of the at least one respiratory parameter reaches a predetermined maximum or minimum value.

[0012] In some embodiments, the one or more respiratory parameters of the user includes any one or a combination of an airflow speed difference, an airflow pressure difference, a minute volume, an inhaled air mixture composition, an exhaled air composition, a physical stress, a mental stress, a breathing motion, a breathing pattern, an oxygen consumption (VO2), an oxygen saturation (SpCh), a tidal volume, a breathing pattern, and a respiratory rate of the user.

[0013] In some embodiments, the controller is configured to operate the air-supply means to perform a carbon dioxide tolerance test based on the one or more respiratory parameters of the user, such that the content of carbon dioxide in the air mixture gradually increases over the first duration of time, wherein the one or more respiratory parameters of the user comprise at least any one or a combination of a minute volume and a tidal volume, and wherein a predefined range and a predetermined maximum value of the one or more respiratory parameters are based on at least any one or a combination of a maximum minute volume and a vital capacity of the user.

[0014] In some embodiments, the controller is configured to operate the air-supply means to perform an oxygen depletion tolerance test based on the one or more respiratory parameters of the user, such that the content of oxygen in the air mixture gradually decreases over the first duration of time, wherein the one or more respiratory parameters of the user comprise at least any one or a combination of the SpC and VO2, and wherein a predefined range and a predetermined minimum value of the one or more respiratory parameters are based on at least any one or a combination of a SpO2 value and a VO2 value of the user which are lower than the SpCh value and the VO2 value of the user at a start of the oxygen depletion tolerance test.

[0015] In some embodiments, the controller is further configured to determine a breathing score for the user based on an extent of variation of the at least one respiratory parameter of the user and a corresponding extent of variation of the air mixture supplied to the user. The breathing score is indicative of a breathing health and physical fitness of the user.

[0016] In some embodiments, the controller is further configured to operate the airsupply means to gradually increase the content of carbon dioxide at predefined intervals over the first duration of time, where a rate of increase of the content of carbon dioxide at each predefined interval is determined based on respiratory, mental or physiological characteristics of the user, to gradually reduce the rate of increase of the content of carbon dioxide as the content of carbon dioxide gets closer to the maximum value of the carbon dioxide in the air mixture tolerable by the user.

[0017] In some embodiments, the controller is configured to operate the air-supply means to decrease the content of carbon dioxide in the air mixture.

[0018] In some embodiments, the controller is configured to operate the air-supply means to increase the content of oxygen in the air mixture.

[0019] In some embodiments, the controller is further configured to operate the airsupply means to gradually decrease the content of oxygen at predefined intervals over the first duration of time, where a rate of decrease of the content of oxygen at each predefined interval is determined based on respiratory, mental or physiological characteristics of the user, to gradually reduce the rate of decrease of the content of oxygen as the content of oxygen gets closer to the minimum value of oxygen in the air mixture tolerable by the user.

[0020] In some embodiments, the system further includes a learning engine communicably coupled to the controller. The learning engine is configured to be trained to predict, based on the recorded changes in the respiratory parameters and the carbon dioxide and oxygen values in the air mixture given to the user, and one or more user body and respiratory parameters, a point of failure for the user. The point of failure is defined as a maximum carbon dioxide value and/or minimum oxygen value in the air mixture at which the corresponding at least one respiratory parameter of the user is outside a natural or recommended respiratory capacity or ability of the user. [0021] In some embodiments, the controller is configured to generate at least one of, based on historical logs of operation of the system, a historical trend of correlation between the variation a value of carbon dioxide or oxygen in the air mixture and a change in at least one respiratory parameter of the user, a historical trend of recorded maximum carbon dioxide values and minimum oxygen values in the air mixture given to the user, or a historical trend of an actually measured maximum value of carbon dioxide or minimum value of oxygen in the air mixture, measured while a corresponding value of the at least one respiratory parameter stays within a predefined range.

[0022] In a second aspect, the present disclosure provides a method to evaluate a breathing response of a user. The method includes receiving, by a controller, from one or more sensors at least one respiratory parameter of the user, where the one or more sensors are configured to measure one or more respiratory parameters of the user. The method includes operating, by the controller, an air-supply means to gradually vary an air mixture, such that a content of at least one of oxygen and carbon dioxide in the air mixture changes continuously over a first duration of time, where the air-supply means is adapted to provide the air mixture to the user, and the air mixture includes at least oxygen and carbon dioxide. The method includes receiving, by the controller, from the one or more sensors, responsive to varying the air mixture, corresponding at least one respiratory parameter of the user at a plurality of time intervals over the first duration of time. The method includes determining, by the controller, a correlation between the variation in a value of carbon dioxide or oxygen in the air mixture and a resulting change in at least one respiratory parameter of the user, or an estimated maximum value of carbon dioxide or estimated minimum value of oxygen in the air mixture tolerable by the user, such that the corresponding value of the at least one respiratory parameter stays within a predefined range, or a maximum value of carbon dioxide or minimum value of oxygen in the air mixture, measured as the value of the at least one respiratory parameter reaches a predetermined maximum or minimum value.

[0023] In some embodiments, the one or more respiratory parameters of the user includes any one or a combination of the airflow speed difference, the airflow pressure difference, the inhaled air mixture composition, the exhaled air composition, the physical stress, the mental stress, the breathing motion, the breathing pattern, the oxygen consumption (VO2), SpO ₂ , tidal volume, the breathing pattern, and the respiratory rate of the user.

[0024] In some embodiments, the method includes determining, by the controller, a breathing score for the user based on an extent of variation of the at least one respiratory parameter of the user and a corresponding extent of variation of the air mixture supplied to the user. The breathing score is indicative of the breathing health and physical fitness of the user.

[0025] In some embodiments, the method includes operating, by the controller, the airsupply means to gradually increase the content of carbon dioxide at predefined intervals over the first duration of time, where a rate of increase of the content of carbon dioxide at each predefined interval is determined based on respiratory, mental or physiological characteristics of the user, to gradually reduce the rate of increase of the content of carbon dioxide as the content of carbon dioxide increases.

[0026] In some embodiments, the method includes operating, by the controller, the airsupply means to perform a carbon dioxide tolerance test based on the one or more respiratory parameters of the user, such that the content of carbon dioxide in the air mixture gradually increases over the first duration of time, wherein the one or more respiratory parameters of the user comprise at least any one or a combination of a minute volume and a tidal volume, and wherein a predefined range and a predetermined maximum value of the one or more respiratory parameters are based on at least any one or a combination of a maximum minute volume and a vital capacity of the user.

[0027] In some embodiments, the method includes operating, by the controller, the airsupply means to perform an oxygen depletion tolerance test based on the one or more respiratory parameters of the user, such that the content of oxygen in the air mixture gradually decreases over the first duration of time, wherein the one or more respiratory parameters of the user include any one or a combination of SpO2 and VO2, and wherein a predefined range and a predetermined minimum value of the one or more respiratory parameters are based on at least any one or a combination of a SpCh value and a VO2 value of the user which are lower than the SpCh value and the VO2 value of the user at a start of the oxygen depletion tolerance test.

[0028] In some embodiments, the method includes operating, by the controller, the airsupply means to gradually decrease the content of oxygen at predefined intervals over the first duration of time, where, the rate of decrease of the content of oxygen is determined based on the respiratory, mental, or physiological characteristics of the user, to gradually reduce the rate of decrease of the content of oxygen as the content of oxygen decreases.

[0029] In some embodiments, the method includes training, by the controller, a learning engine, to predict, based on the recorded changes in the respiratory parameters and the carbon dioxide and oxygen values in the air mixture given to the user, and one or more user body and respiratory parameters, a point of failure for the user. The point of failure is defined as the maximum carbon dioxide value or minimum oxygen value in the air mixture at which the corresponding at least one respiratory parameter of the user is outside the natural or recommended respiratory capacity or ability of the user.

[0030] In a third aspect, the present disclosure provides an apparatus to evaluate a breathing response of a user. The apparatus includes an air-supply means adapted to provide an air mixture to the user, wherein the air mixture comprises at least oxygen and carbon dioxide. The apparatus includes one or more sensors configured to measure one or more respiratory parameters of the user. The apparatus includes a controller communicably coupled with the air- supply means and the one or more sensors, and including a processor and a memory communicably coupled with the processor. The controller is configured to receive, from the one or more sensors, at least one respiratory parameter of the user. The controller is configured to operate the air-supply means to gradually vary the air mixture, such that a content of one of oxygen and carbon dioxide in the air mixture changes continuously over a first duration of time. The controller is configured to receive, from the one or more sensors, responsive to varying the air mixture, the corresponding at least one respiratory parameter of the user over the first duration of time. The controller is configured to determine a correlation between the variation in a value of carbon dioxide or oxygen in the air mixture and a resulting change in at least one respiratory parameter of the user, or an estimated maximum value of carbon dioxide or estimated minimum value of oxygen in the air mixture tolerable by the user, such that the corresponding value of the at least one respiratory parameter stays within a predefined range, or a maximum value of carbon dioxide or minimum value of oxygen in the air mixture, measured as the value of the at least one respiratory parameter reaches a predetermined maximum or minimum value.

[0031] Various embodiments adjust the oxygen and carbon dioxide levels of the air mixture continuously and gradually, so that the body and the respiratory system of the user may slowly, continuously, and gradually adjust to and respond to the changing air mixture, without causing unnecessary stress to the user. This continuous and gradual change in the air mixture allows a slow, continuous, and gradual response by the users’ body and respiratory system and helps achieve a very accurate and precise result from a carbon dioxide tolerance test or oxygen depletion tolerance test. Also, as the actual carbon dioxide or oxygen levels in the air mixture are coming closer to the maximum or minimum levels tolerable by the user, the adjustment in the carbon dioxide and oxygen levels in the air mixture should take place at a gradually reducing rate to achieve a more accurate and detailed final testing result. [0032] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0034] FIG. 1 illustrates an example representation of a system for evaluating a breathing response of a user, according to an embodiment of the present disclosure;

[0035] FIG. 2 illustrates an example flow chart of a method for evaluating the breathing response of the user, according to an embodiment of the present disclosure;

[0036] FIG. 3 A illustrates an example flow chart of a method for testing carbon dioxide tolerance of the user, according to an embodiment of the present disclosure;

[0037] FIGs. 3B and 3C illustrate example charts depicting carbon dioxide tolerance test results, according to an embodiment of the present disclosure;

[0038] FIG. 4A illustrates an example flow chart of a method for testing oxygen altitude depletion of the user, according to an embodiment of the present disclosure;

[0039] FIG. 4B illustrates an example chart depicting oxygen depletion tolerance test result, according to an embodiment of the present disclosure; and

[0040] FIG. 5 illustrates an exemplary schematic block diagram of a computer system for implementation of the system of FIG. 1.

DETAILED DESCRIPTION

[0041] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such details as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.

[0042] In a first aspect, the present disclosure provides a system to evaluate a breathing response of a user. The system includes an air-supply means adapted to provide an air mixture to the user, where the air mixture includes at least oxygen and carbon dioxide, one or more sensors configured to measure corresponding one or more respiratory parameters of the user, and a controller communicably coupled with the air-supply means and the one or more sensors. The controller includes a processor and a memory communicably coupled with the processor. The controller is configured to receive, from the one or more sensors, at least one respiratory parameter of the user, and operate the air-supply means to gradually and continuously vary the air mixture, such that a content of one of oxygen and carbon dioxide in the air mixture changes significantly over a first duration of time. The controller is configured to receive, from the one or more sensors, the corresponding at least one respiratory parameter of the user over the first duration of time, as the at least one respiratory parameter changes in response to the gradually varying air mixture. The controller is configured to determine a correlation between the variation in the air mixture and a change in at least one respiratory parameter of the user, or an estimated maximum value of carbon dioxide or estimated minimum value of oxygen in the air mixture tolerable by the user, such that the corresponding value of the at least one respiratory parameter stays within a predefined range, or a maximum value of carbon dioxide or minimum value of oxygen in the air mixture, measured as the value of the at least one respiratory parameter reaches a predetermined maximum or minimum value.

[0043] In a second aspect, the present disclosure provides a method to evaluate a breathing response of a user. The method includes receiving, by a controller, from one or more sensors at least one respiratory parameter of the user, where the one or more sensors are configured to measure corresponding one or more respiratory parameters of the user. The method includes operating, by the controller, an air-supply means to gradually vary an air mixture, such that a content of one of oxygen and carbon dioxide in the air mixture changes continuously over a first duration of time, where the air-supply means is adapted to provide the air mixture to the user, and the air mixture includes at least oxygen and carbon dioxide. The method includes receiving, by the controller, from the one or more sensors, responsive to varying the air mixture, corresponding at least one respiratory parameter of the user over the first duration of time. The method includes determining, by the controller, a correlation between the variation in the air mixture and a change in at least one respiratory parameter of the user, or an estimated maximum value of carbon dioxide or estimated minimum value of oxygen in the air mixture tolerable by the user, such that the corresponding value of the at least one respiratory parameter stays within a predefined range, or a maximum value of carbon dioxide or minimum value of oxygen in the air mixture, measured as the value of the at least one respiratory parameter reaches a predetermined maximum or minimum value.

[0044] In a third aspect, the present disclosure provides an apparatus to evaluate a breathing response of a user. The apparatus includes an air-supply means adapted to provide an air mixture to the user, wherein the air mixture comprises at least oxygen and carbon dioxide. The apparatus includes one or more sensors configured to measure corresponding one or more respiratory parameters of the user. The apparatus includes a controller communicably coupled with the air-supply means and the one or more sensors, and including a processor and a memory communicably coupled with the processor. The controller is configured to receive, from the one or more sensors, at least one respiratory parameter of the user. The controller is configured to operate the air-supply means to gradually vary the air mixture, such that a content of one of oxygen and carbon dioxide in the air mixture changes continuously over a first duration of time. The controller is configured to receive, from the one or more sensors, responsive to varying the air mixture, the corresponding at least one respiratory parameter of the user over the first duration of time. The controller is configured to determine a correlation between the variation in the air mixture and a change in at least one respiratory parameter of the user, or an estimated maximum value of carbon dioxide or estimated minimum value of oxygen in the air mixture tolerable by the user, such that the corresponding value of the at least one respiratory parameter stays within a predefined range, or a maximum value of carbon dioxide or minimum value of oxygen in the air mixture, measured as the value of the at least one respiratory parameter reaches a predetermined maximum or minimum value.

[0045] The various embodiments throughout the disclosure will be explained in more details with reference to FIGs. 1-5.

[0046] FIG. 1 illustrates an example representation 100 of a system for evaluating a breathing response of a user, according to an embodiment of the present disclosure.

[0047] The system 110 may be a carbon dioxide (CO2) tolerance testing system, CO2 sensitivity testing system, CO2 respiratory response testing system, or an oxygen (O2) altitude depletion testing system. The system 110 may slowly increase levels of CO ₂ in the inhaled air, observe changing characteristics of breathing, such as, without limitations, a respiratory rate, a tidal volume, a minute volume, a respiratory muscle movement, an airflow force, etc., of a user and respond to those changing characteristics during a CO2 tolerance test. The testing result is an actual CO ₂ percentage number, i.e., the CO ₂ content of the inhaled air that the user is able to sustain for a longer time. The higher the CO ₂ percentage number, the higher the user’s C0 ₂ tolerance. The system 110 may perform the CO ₂ tolerance testing procedure repeatedly and accurately.

[0048] The CO ₂ tolerance testing procedure may be easily implemented in various respiratory devices, breathing devices, or breath testing devices that have the capability of precisely setting the CO ₂ value of the inhaled air. Examples of respiratory devices, breathing devices, or breath testing devices may include, but are not limited to, a continuous positive airway pressure system, a bilevel positive airway pressure system, a portable emergency oxygen system, a nebulizer, a pulse oximetry meter, a home oxygen concentrator, a suction machine, VO ₂ max testing machine, a breathalyzer, and the like. When the CO ₂ tolerance testing procedure is implemented in the respiratory devices, the breathing devices, or the breath testing devices, they gain the unique capability to perform the CO ₂ tolerance test and have a clear advantage and distinction over other CO ₂ enrichment devices that are not able to perform the CO ₂ tolerance testing function. Further, during the CO ₂ tolerance testing procedure, the user may be provided with an instruction to follow their "instinct to breathe" or “urge to breathe”, and not to breathe more or less than what they physically and mentally feel they need to breathe. The user may be instructed not to change their breathing playfully without any reason, as that may affect the testing result.

[0049] In some embodiments, in the CO ₂ tolerance testing procedure, a person/user undergoing the test is supplied with, for example, a mask that supplies air with a gradually increasing CO ₂ content. Alternatively, delivery mechanisms such as, without limitations, a helmet, a mouthpiece, a tent, or a room fitted with appropriate technology to enrich the air to changing CO ₂ percentage requirements may be used. The respiratory parameters of the person may be analyzed, establishing that their maximal voluntary ventilation (MMV) or maximal breathing capacity (MBC) is 120 liters air per minute. It may then be determined that a suitable “Goal Minute Volume” for the CO ₂ tolerance test may be set at 100 liters per minute, comfortably below the MMV of 120 liter per minute. The CO ₂ enrichment may then start at a very low value, i.e., 0.1% or 0.5% or the like. Then, for every 1, 2, 5, 10, 15, or 30 seconds, the CO ₂ percentage may be raised, for example from 0.6%, 0.7%, etc., slowly continuing to 2.5%, 2.6%, 4.0%, 4.1%, etc., until the minute volume reaches the predetermined value of 100 liters per minute at which the CO ₂ percentage has reached that may be considered as a maximum sustainable CO ₂ percentage for that person. If the CO ₂ percentage rises too high, i.e., to the point of failure of 120 liters, the person may get a panicky feeling, lose a sense of control of breathing, and may feel they need to immediately take off the mask to get fresh air (air with low CO ₂ percentage). When the minute volume reaches a value close to the point of failure, the speed of increase of the CO ₂ percentage may be very slow as the reaction in minute volume increase may be strong and unpredictable. At times, the CO ₂ percentage may be lowered to give the body some rest, and observe the body’s reaction and the mental reaction to the lowered CO ₂ percentage. Further, a respiratory tidal volume, a respiratory rate, a breathing pattern, airflow speed, an airflow pressure, forcefulness of breathing muscle movement, O ₂ content of air, stress response, etc., may be measured and recorded as an alternative or supplement to minute volume. The minute volume may be measured together with the inhaled CO ₂ percentage. The minute volume may be estimated using any of the other indicators, especially respiratory exertion, airflow speed, airflow pressure, diaphragm movement, forcefulness of breathing muscle movement, range of breathing muscle movement, etc. The final score or the test result may be a maximum sustainable CO ₂ percentage for the user (for example, 6.5%, 5.4%, 5.5%, 7.8%, 7.9%, etc.,). This may best be a CO ₂ percentage point recorded below the point of failure, as the actual point of failure itself may be a physically and mentally tough experience. Also, a chart may be produced to show the test results in high detail, as shown in FIGs. 3B and 3C. The chart may show the CO ₂ percentage and the minute volume over time, or it may show the recorded CO ₂ percentage values plotted as a line in the chart against the recorded values of the respiratory parameter.

[0050] The point of failure and the maximum sustainable CO ₂ percentage level may be flexibly defined as a “Goal Minute Volume”. The goal minute volume is a predefined high minute volume at which the user is comfortable, breathing air with enriched level of CO ₂ percentage for a longer time. In the CO ₂ tolerance testing procedure, the CO ₂ percentage test result may be defined as an actual CO ₂ percentage attained when the user crosses, reaches, or goes beyond the goal minute volume.

[0051] In some embodiments, the system 110 may perform a similar test for oxygen depletion tolerance by slowly reducing the O ₂ content of the inhaled air, and may observe the changing characteristics of breathing. The system 110 may be used as a general physical fitness testing system or a general health testing system by, for example, mountaineers to test their fitness or health to climb up the mountain. The testing result may be evaluated in terms of a goal value of oxygen saturation (SpO ₂ ) rather than a goal minute volume in the oxygen depletion tolerance test. The tests performed by system 110 may be done while sitting, walking or running.

[0052] In some embodiments, the system 110 may include an air supply means 102, one or more sensors 104, and a controller 108. In some embodiments, the system 110 may include a breathing response evaluating apparatus. The breathing response evaluating apparatus may include the air supply means 102, the one or more sensors 104, and the controller 108. In some embodiments, the air-supply means 102 may be adapted to provide an air mixture to the user. The air mixture includes at least oxygen and carbon dioxide.

[0053] In some embodiments, the system 110 may include one or more sensors 104. The one or more sensors 104 may be individually referred to as “the sensor 104” and collectively referred to as “the sensors 104”. In some embodiments, all the sensors 104 may be provided on the system 110. The sensors 104 may include, without limitations, a pressure sensor, a tension sensor, a distance sensor, an optical sensor, a motion sensor, an air pressure sensor, an airflow sensor, an infrared sensor, a user stress sensor, a CO2 sensor, an O2 sensor, a heart rate sensor, a blood pressure sensor, a SpO ₂ sensor, stress sensor, brainwave sensor, VO ₂ sensor, etc.

[0054] In some embodiments, some sensors 104 (e.g., heart rate sensor, user stress sensor, air-pressure sensor, CO2 sensor, oxygen sensor, etc.) may be configured to measure various respiratory parameters of the user. The respiratory parameters of the user, include, without limitations, an airflow speed difference, an airflow pressure difference, the minute volume, an inhaled air mixture composition, an exhaled air composition, a physical stress, a breathing motion, an oxygen consumption (VO2), an oxygen saturation (SpCh), a tidal volume, a respiratory rate of the user, a breathing pattern, etc.

[0055] The system 110 may further include a controller 108 communicably coupled with the air-supply means 102 and the one or more sensors 104. The controller 108 may include a memory 112 and a processor 114 communicably coupled to the memory 112. The memory 112 may store instructions executable by the processor 114 to implement the functionality of the controller 108. The processor 114 may include, for example, without limitations, microprocessors, microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuits, any devices that manipulate data or signals based on operational instructions, and the like. Among other capabilities, the processor 114 may fetch and execute computer-readable instructions in the memory operationally coupled with the system 110 for performing tasks such as data processing, input/output processing, feature extraction, and/or any other functions. Any reference to a task in the present disclosure may refer to an operation being or that may be performed on data.

[0056] In some embodiments, the system 110 may include an interface 106. In some embodiments, the controller 108 may be associated with the interface 106. The interface 106 may include a variety of interfaces, for example, interfaces for data input and output devices, referred to as I/O devices, storage devices, and the like. The interface 106 may also provide a communication pathway for one or more components of the controller 108. The controller 108 may be communicably coupled to a database 124. The database 124 may be configured to store data generated during operation of the controller 108. An example of the data generated may include logs of operation. The database 124 may also be configured to store other data such as data pertaining to the user of the system 110.

[0057] In some embodiments, the controller 108 may include a receiver 116, a determination engine 118, a learning engine 120, and other engine(s) 122. The memory 112, the processor 114, the receiver 116, the determination engine 118, the learning engine 120, and other engine(s) 122 may be operatively connected with each other. The other engine(s) 122 may include engines configured to perform one or more functions ancillary functions associated with the controller 108. The other engine(s) 122 may be selected from any one of an indication engine, an input/output engine, and the like.

[0058] In some embodiments, the controller 108 may receive at least one respiratory parameter of the user from the one or more sensors 104 via the receiver 116. In some embodiments, the controller 108 may receive the corresponding at least one respiratory parameter of the user over a first duration of time via the receiver 116, as the at least one respiratory parameter changes in response to the gradually varying air mixture from the one or more sensors 104.

[0059] In some embodiments, the controller 108 may receive, from the one or more sensors 104, via the receiver 116, the corresponding at least one respiratory parameter of the user at a plurality of time intervals over the first duration of time, as the respiratory parameter changes in response to the gradually varying air mixture.

[0060] In some embodiments, the controller 108 may operate the air-supply means 102 to gradually and continuously vary the air mixture, such that the content of one of oxygen and carbon dioxide in the air mixture changes significantly over the first duration of time. In some embodiments, the controller 108 may operate the air-supply means 102 to increase the content of carbon dioxide in the air mixture. In some embodiments, the controller 108 may operate the air-supply means 102 to gradually increase the content of carbon dioxide in the air mixture at predefined intervals over the first duration of time. At each predefined interval, the carbon dioxide content may be increased at a rate lower relative to a previous predefined interval, based on the user’s respiratory parameters. In some embodiments, the controller 108 may be configured to operate the air-supply means 102 to decrease the content of carbon dioxide in the air mixture. [0061] In some embodiments, the controller 108 may be configured to operate the airsupply means 102 to increase the content of oxygen in the air mixture. In some embodiments, the controller 108 may be configured to operate the air-supply means 102 to gradually decrease the content of oxygen in the air mixture. In some embodiments, the controller 108 may be further configured to operate the air-supply means 102 to gradually decrease the content of oxygen at predefined intervals over the first duration of time. At each predefined interval, the oxygen content is increased at a rate lower relative to a previous predefined interval, based on the user’s respiratory parameters.

[0062] In some embodiments, the controller 108 may determine a correlation between the variation in the air mixture and the change in at least one respiratory parameter of the user via the determination engine 118. In some embodiments, the controller 108 may determine an estimated maximum value of carbon dioxide or minimum value of oxygen in the air mixture tolerable by the user via the determination engine 118, such that the corresponding value of the at least one respiratory parameter stays within a predefined range. In some embodiments, the controller 108 may, via the determination engine 118, determine a maximum value of carbon dioxide or minimum value of oxygen in the air mixture, measured as the value of the at least one respiratory parameter reaches a predetermined maximum or minimum value.

[0063] In some embodiments, the controller 108, via the determination engine 118, may determine a breathing score for the user based on an extent of variation of the at least one respiratory parameter of the user and a corresponding extent of variation of the air mixture supplied to the user. The breathing score may be indicative of a breathing health and physical fitness of the user.

[0064] In some embodiments, the controller 108 may include a learning engine 120. The learning engine 120 may be communicably coupled to the controller 108. The learning engine 120 may be configured to be trained to predict, based on the recorded carbon dioxide and oxygen values in the air mixture given to the user, and one or more user body parameters, a point of failure for the user. The point of failure may be defined as a maximum carbon dioxide value or minimum oxygen value in the air mixture at which the corresponding at least one respiratory parameter of the user is outside a natural or recommended respiratory capacity or ability of the user.

[0065] In some embodiments, the system 110 may include a database 124. The database 124 may be communicably coupled with the controller 108. In some embodiments, the controller 108 may be configured to generate a log of operations and store the log of operations in the database 124. In some embodiments, the controller 108 may be configured to generate, based on historical logs of operation of the system 110, a historical trend of correlation between the variation in the air mixture and the change in at least one respiratory parameter of the user, or the recorded maximum carbon dioxide and minimum oxygen values in the air mixture given to the user, or an actually measured maximum value of carbon dioxide or minimum value of oxygen in the air mixture, measured while the corresponding value of the at least one respiratory parameter stays within a predefined range.

[0066] In some embodiments, the system 110 may further include an electronic device (not shown). The electronic device may be associated with the user. The electronic device may be communicably coupled to the controller 108 or the system 110. The electronic device may be used to provide data to or receive data from any one or more components of the system 110. In some instances, the electronic device may include audio-visual devices, such as display screens, Light Emitting Diode (LED) lighting displays, speakers, etc. The electronic device may be any electrical, electronic, electromechanical, or computing device. The electronic device may include, without limitations, electronic monitoring devices. Examples of electronic monitoring devices may include, without limitations, smart inhalers, wearable, unobtrusive inertial-sensor-based device, and the like.

[0067] The system 110 may further include a transceiver unit (not shown) communicably coupled to the controller 108. The transceiver unit may be configured to facilitate exchange of data signals between the controller 108 and the system 110. In some embodiments, the transceiver unit may be a part of the electronic device.

[0068] The system 110 may further include an indication unit (not shown) communicably coupled with the controller 108. In some embodiments, the indication unit may be provided on the electronic device. In some embodiments, the indication unit may be a separate unit. The indication unit may be configured to indicate data generated by the controller 108 during an operation of the controller 108. In some embodiments, the indication unit may be configured to indicate the data in the form of a visual data, an audio data, a haptic data, a text data, or combinations thereof. In some embodiments, the indication unit may include any one or a combination of a display device, an audio device, and a haptic device (not shown).

[0069] Further, the system 110 may also include other engines 122 or units such as a display unit, an input unit, an output unit and the like, however, the same are not shown in the FIG. 1, for the purpose of clarity. Also, in FIG. 1, only few units are shown; however, the system 110 may include multiple such units or the system 110 may include any such numbers of the units, obvious to a person skilled in the art or as required to implement the features of the present invention.

[0070] FIG. 2 illustrates an example flow chart 200 of a method for evaluating the breathing response of the user, according to an embodiment of the present disclosure.

[0071] With reference to FIG. 2, at 210, the method may include receiving and analyzing, by a controller (e.g., 108), at least one respiratory parameter of the user from one or more sensors 104 of a system 110. The at least one respiratory parameter may be, for example, but not limited to, maximal voluntary ventilation (MW), maximal breathing capacity (MBC), vital capacity, current SpO ₂ , etc. The MW and MBC may be equal to a maximum value of minute volume that a user achieves. The one or more sensors 104 may be configured to measure corresponding one or more respiratory parameters of the user.

[0072] At 220, the method may include setting an appropriate goal for the at least one respiratory parameter. The goal for the at least one respiratory parameter may be a minute volume goal which is lower than the MMV, or an SpO ₂ goal which is lower than the current SpO ₂ , etc. For example, if the person’s MMV is 120 liters per minute, the minute volume goal may be set at 100 liters per minute. Or if the current SpO ₂ is 97%, the SpO ₂ goal may be set at 87%. The minute volume goal may be set at 60% to 99% of the user’s MMV.

[0073] At 230, the method may include enabling the user to connect to an air-supply means (e.g., 102) of the system 110.

[0074] At 240, the method may include operating, by the controller 108, the air-supply means 102 to gradually vary an air mixture, such that a content of one of oxygen and carbon dioxide in the air mixture changes continuously over a first duration of time. The air-supply means 102 may be adapted to provide the air mixture to the user. The air mixture includes at least oxygen and/or carbon dioxide. The air-supply means 102 may be preferably varied in a slow and gradual manner to give the body time to significantly respond (by adjusting the breathing) to the current characteristics of the air mixture as the air mixture is being varied.

[0075] At 250, the method may include receiving, by the controller 108, from the one or more sensors 104, responsive to varying the air mixture, corresponding at least one respiratory parameter of the user over the first duration of time.

[0076] At 260a, the method may include determining, by the controller 108, a correlation between the variation in the air mixture and a change in at least one respiratory parameter of the user. At 260b, the method may include determining, by the controller 108, an estimated maximum value of carbon dioxide and/or minimum value of oxygen in the air mixture tolerable by the user, such that the corresponding value of the at least one respiratory parameter stays within a predefined range. At 260c, the method may include determining, by the controller 108, a maximum value of carbon dioxide and/or minimum value of oxygen in the air mixture, measured as the value of the at least one respiratory parameter reaches a predetermined maximum or minimum value. The method may perform at least one of 204a, 204b, and 204c based on the respiratory parameter of the user received from the one or more sensors 104.

[0077] FIG. 3 A illustrates an example flow chart of a method for testing carbon dioxide tolerance of the user, according to an embodiment of the present disclosure.

[0078] With reference to FIG. 3 A, the carbon dioxide tolerance of the user may be tested by the following steps. At 310, the method may include measuring or analyzing a maximum minute volume (MMV) of a person. The MMV may be called as a MW or a MBC. Alternatively, rather than measuring the MMV of the person, a standard estimation value may be used based on body size, age, and sex of the person. MMV may also be estimated using other tests such as by measuring forced expiratory volume (in 1 second) of the person or by measuring the vital capacity of the person. The average fit young male adult may have the MMV of about 170 liter/min. Actual values may depend on body size, age, and sex of the person.

[0079] At the same time, the method may include monitoring breathing pattern and characteristics of the person using various sensors (e.g., 104) sensing data regarding any one of the characteristics of the person and/or their airflow. The characteristics of the person may include, without limitations a minute breathing volume (liters/minute), a tidal volume, a respiratory rate, a minute volume, an airflow speed difference (including changes and minimum and maximum values during inhalation and exhalation), an airflow pressure (including changes and minimum and maximum values during inhalation and exhalation), a heart rate, a Heart Rate Variability (HRV), a blood pressure, a blood oxygen level, a blood pressure, an infrared sensor (heat of exhaled air and body temperature), a brainwave frequency, a galvanic skin response, body temperature, intensity of breathing muscle movement, body oxygen consumption rate, carbon dioxide production rate or metabolism rate, oxygen content of inhaled air, oxygen content of exhaled air, and carbon dioxide content of exhaled air.

[0080] The characteristics of the person may be monitored to observe how the person’s breathing is dealing with the higher carbon dioxide percentage and how close the person is to reach the breathing point of failure. The point of failure may be defined in terms of an airflow speed difference, an airflow pressure difference, a minute breathing volume, stress levels, a difference between the carbon dioxide or oxygen content of inhaled and exhaled air, and a range of breathing muscle movement, etc.

[0081] The airflow speed difference may be the difference between the speed of exhalation airflow (as a positive value) and the speed of inhalation airflow (as a negative value). If this difference becomes larger, the person is moving close to the point of failure. The airflow pressure difference is the difference between the air pressure measured during the exhalation airflow and the air pressure measured during the inhalation airflow. If this difference becomes larger, the person is moving close to the point of failure. The minute breathing volume is referred to as the volume of liters of air the person breathes per minute, which is related to the current tidal volume, the respiratory rate, etc. The stress levels may go up eventually as the person is coming closer to the point of failure. It is a stressful event to be very near or at the point of failure. The sensors (e.g., 104) that measure stress levels may also be used to gather relevant values, such as the brainwave frequency, the galvanic skin response, the body temperature, the heart rate, the HRV, the blood pressure, etc.

[0082] The difference between the carbon dioxide or oxygen content of inhaled and exhaled air may be corrected for minute breathing volume. The result of difference may be an estimate of the total quantity of carbon dioxide molecules produced or the oxygen consumption (VO2) by the body. If the total quantity of exhaled carbon dioxide molecules goes down while VO ₂ stays equal or goes up, it may mean that the carbon dioxide is accumulating in the body of the person which may eventually lead to point of failure. The difference between the carbon dioxide and oxygen content of inhaled and exhaled air may be used to estimate how close the person is to the point of failure.

[0083] The range of breathing muscle movement may be measured through a complete breathing cycle of inhalation and exhalation. If the breathing muscles move more (higher maximum position and lower minimum position in terms of respiratory muscular contraction and expansion), the person is closer to the point of failure. This may be measured using, for example, a camera, gyroscope, pressure or tension sensors in a breathing belt/harness, etc.

[0084] In some embodiments, rather than the point of failure, the maximum sustainable carbon dioxide percentage may be used, shown, or measured. The maximum sustainable carbon dioxide percentage is the highest carbon dioxide percentage that the person’s breathing successfully, comfortably and sustainably deals with (without problems) for a period of at least a few minutes, in a way that the person’s brain is also comfortable and without high levels of stress and without signs of air hunger or mentally desiring more air than their respiratory system is able to deliver. The maximum sustainable carbon dioxide percentage may always be a bit lower than the carbon dioxide percentage at the point of failure.

[0085] In some embodiments, the point of failure may be estimated from basic health parameters of the person. The basic health parameters of the person may include, without limitations, height, weight, gender, body type, body build, lung capacity, athletic performance, and estimated level of fitness/health of the person. The value of the point of failure and the maximum sustainable CO2% may depend on, for example, a size of the lungs (liter volume), lung capacity, a strength of the breathing muscles, and tolerance level of brain and body to increased levels of carbon dioxide in the inhaled air.

[0086] At 320, a goal minute volume (GMV) to be used for the test may be set. A maximum sustainable carbon dioxide percentage level while still being under the point of failure may be flexibly defined as occurring at the GMV. The GMV is a predefined high minute volume at which the person is comfortable, breathing air with enriched level of carbon dioxide percentage for a longer time. The GMV may be normally set at 60% to 99% of the person’s MMV, but may be set much lower as well. 60% of MMV may be a quite comfortable testing procedure for the person. 99% of MMV may be a tough test for the person with the risk of the test being too hard and the person may be unable to finish the test due to a high level of mental and physical stress. If the person’s real MMV is 140 1/m and the GMV is set at 85% of MMV, the GMV may be 119 1/m.

[0087] At 330, the method may include enabling the person to connect to an air- supply means (e.g., 102) of the system 110. At 340, the person may be supplied with a mask to use and the person may start breathing with the mask. The mask may be connected to a carbon dioxide enrichment device, for example, a rebreather device or an air mixer device which mixes an accurate amount of carbon dioxide into the regular air, and increases the carbon dioxide level of the inhaled air. Then, the carbon dioxide percentage of the inhaled air is gradually increased, starting with a very low value (for example, 0.5%). As the carbon dioxide is gradually raised, at least the minute volume is measured continuously throughout the test. Further other health, breathing and stress variables may also be measured during the test. The carbon dioxide percentage of the inhaled air may be increased at moderate speed in the beginning but more slowly when reaching close to the GMV, to give the body time to properly respond to the increasing level of carbon dioxide in the inhaled air. Sometimes the carbon dioxide percentage may be lowered when the actual minute volume is close to the GMV to see what happens to the minute volume, i.e., to determine how much minute volume goes down or up and observe the changes in stress level, heart rate, etc. [0088] In some embodiments, historical sensor data may be used to ascertain how close the person’s respiratory system is to the point of failure and the maximum sustainable carbon dioxide percentage (in terms of carbon dioxide percentage and/or maximum minute breathing volume, etc.,) based on the sensor data received from the sensors (e.g., 104). If the person is close to the point of failure, the speed of the increase in carbon dioxide percentage may be relatively low (maybe increase by 0.1% every 20 to 60 secs). If the person is far from the point of failure, the speed of the increase in carbon dioxide percentage may be relatively higher as the impact from increasing it (on the breathing patterns) is still low and the person may not notice the additional increase (maybe increase by 0.1% every 2, 5 or 10 secs).

[0089] At 350, the ventilation changes may be observed as the carbon dioxide percentage is changed. Rather than the minute volume, other indicators may also be used as a replacement or a supplement during the test. In particular, a score for minute volume which values the most recent ventilation values more highly than values recorded 30 seconds ago (in a weighted average) may be obtained, for example as an airflow pressure difference score representing the variance in air pressure in the breathing mask or a breathing tube over the past 30 seconds. Most recent measurements may carry more weight than previously measured values.

[0090] When the person’s actual minute volume is equal to or higher than the GMV, the test may end and the actual carbon dioxide percentage of the inhaled air (at GMV) may be recorded as the primary test result. The secondary test result may be a whole progression of datapoints for a complete test, i.e., MV at each carbon dioxide percentage over time. The third test result may be any derivate values, such as a rate or amount of increase of MV when the carbon dioxide percentage goes up from 2% to 3%, etc. Or values such as the minute volume when the carbon dioxide percentage is equal to 5% or the carbon dioxide percentage when GMV is equal to 85% of MMV At the end of the test, the person may take of the mask, or the person may take off the mask at any time to end the test if they feel the need to stop. The carbon dioxide percentage of the inhaled air may go back to 0% automatically when MV=GMV to end the test. The total duration of the test may be about 3 to 5 minutes. The higher the final achieved carbon dioxide percentage, the better the test result and the higher the carbon dioxide tolerance of the person, or the user, or a test subject.

[0091] At 360a, the method may include determining, by the controller 108, a correlation between the variation in the carbon dioxide level in the air mixture and the resulting change in the minute volume of the person. At 360b, the method may include determining, by the controller 108, an estimated maximum percentage of carbon dioxide in the air mixture tolerable by the person, such that the corresponding minute volume stays under the GMV. At 360c, the method may include determining, by the controller 108, a maximum percentage of carbon dioxide in the air mixture, measured as the actual minute volume reaches the GMV. The method may perform at least one of 360a, 360b, and 360c based on the minute volume and/or the vital capacity of the person.

[0092] The test may be repeated several times and may also be used as a breath training procedure or breath training program to measure and improve the carbon dioxide tolerance of the person over a period of weeks, months and years. When repeating the carbon dioxide tolerance test several times in a single practice session, the later/sub sequent carbon dioxide tolerance testing scores should ideally be higher than the first carbon dioxide tolerance test score, due to the learning effect or training effect of a respiratory center in the brain which determines the neurological “respiratory drive” or the “urge to breathe”. For example, if the first test result of carbon dioxide GMV equal to 85% (the carbon dioxide measured at point where GMV=85% of MMV) is 5.87%, the second test result may be 5.93% and the third test result may be 6.05%. The improving carbon dioxide tolerance test results show that the person experiences a positive training effect by doing the test several times in a row, i.e., the respiratory response and health and fitness of the user are improved by repeatedly doing the carbon dioxide tolerance test. If the carbon dioxide tolerance test result is worsened in the later repeated tests, it indicates worsening of the performance, possibly due to overtraining and high user stress values during the test. Also, the test may initially be done using a relatively lower GMV of, for example, 75% of MMV, followed by a medium GMV of 80% of MMV when performing the test for a second time, and then finally a relatively higher GMV of 85% of MMV when performing the test for a third time. Further, the GMV may also be set as a plain absolute value of, for example, 110, 120, or 130 (1/m), etc.

[0093] During the test, values of, for example, without limitations, the current minute volume, the GMV, current carbon dioxide percentage, current oxygen percentage, respiratory ventilation values, airflow values, oxygenation values, stress values, heart values, etc., may be displayed.

[0094] The test result may be either the actual or estimated point of failure in terms of carbon dioxide percentage of the inhaled and/or exhaled air, or just below the actual or estimated point of failure in terms of carbon dioxide percentage of the inhaled and/or exhaled air), or the maximum sustainable carbon dioxide percentage. Or it may be the carbon dioxide percentage at which the person is able to sustainably breathe in relative comfort at a high minute breathing volume. The test result may be calculated and shown when the testing program is naturally completed, or upon the person ending the test intentionally/manually (pressing a button or taking the mask off), or upon a respiratory therapist or a medical professional ending the test for them. All the data of the test result may be put into a chart, as shown in FIGs. 3B and 3C, showing a timeline of the session and how the carbon dioxide percentage and the minute breathing volume go up and down over time during the test. The timeline chart may emphasize the causal relation between the carbon dioxide percentage and the resultant minute volume.

[0095] The carbon dioxide tolerance test may be performed to provide the person/user with a breathing performance metric and a health and fitness metric. The carbon dioxide tolerance test results may be used to determine the level of carbon dioxide in the inhaled air that the person may able to breathe with for a longer, extended time in a quite comfortable manner. It gives a performance metric for the breathing which we can compare to other people’s scores and to one’s own scores over time. The carbon dioxide tolerance training may be performed for better performance of divers, free-divers, mountaineers, and the like for altitude training and for performing better at various breathing exercise programs, sports, athletics, yoga, meditation, etc.

[0096] FIG. 4A illustrates an example flow chart of a method for testing the oxygen altitude depletion response of the user, according to an embodiment of the present disclosure. [0097] With respect to FIG. 4A, the oxygen depletion tolerance test may be done in a similar manner as carbon dioxide tolerance test. The oxygen depletion tolerance test may be performed by following tests. At 410, the method may include determining health and fitness of a person and measuring the actual current oxygen saturation (SpO ₂ ) and historical SpO ₂ or the actual current oxygen consumption (VO ₂ ) and historical VO ₂ of the person. The SpO ₂ may be an oxygen saturation level of the blood. At 420, goal SpO ₂ (and/or VO ₂ ) to be used for the test may be set, also considering the historical SpO ₂ (and/or VO ₂ ) values of the user. At 430, the method may include enabling the user to connect to an air-supply means (e.g., 102) of the system 110. At 440, the oxygen level of the inhaled air may be gradually reduced or decreased. As the oxygen level of inhaled air goes gradually and slowly down, the SpO ₂ (and/or VO ₂ ) may also slowly go down. At 450, the changing characteristics of breathing and the ventilation changes may be observed.

[0098] At 460a, the method may include determining a correlation between the variation in the oxygen level in the air mixture and the resulting change in the SpO ₂ (and/or VO ₂ ) of the person. At 460b, the method may include determining an estimated minimum percentage of oxygen in the air mixture tolerable by the person, such that the corresponding SpO ₂ (and/or V0 ₂ ) stays above the goal SpO ₂ (and/or goal VO ₂ ). At 460c, the method may include determining a minimum percentage of the oxygen in the air mixture, measured as the actual SpO ₂ (and/or VO ₂ ) reaches the goal SpO ₂ (and/or goal VO ₂ ). The method may perform at least one of 460a, 460b, and 460c based on the SpO ₂ (and/or VO ₂ ) of the person.

[0099] The test may be stopped when reaching, for example, 85% SpO ₂ (and/or a similarly lowered value of VO ₂ ). In harsh stress tests (for athletes, mountaineers, and extreme altitude testing) the SpO ₂ (and/or VO ₂ ) may go down much lower to 60% SpO ₂ or even lower. The person who achieves, for example, 85% SpO ₂ at 13% oxygen content of the inhaled air may have a better test result than the person who achieves 85% SpO ₂ at 15% oxygen content of the inhaled air. The person who achieved 85% SpO ₂ at 13% oxygen content of the inhaled air maintained a relatively higher SpO ₂ as the oxygen level of the inhaled air went down.

[0100] The test may be performed on different times and days and the progress of the person or the test subjects made in their training and preparation may be reviewed. Therefore, the test may be standardized and the test results may be recorded in various ways so that the test results may be better reviewed over time. For example, the test may stop when reaching an oxygen content of the inhaled air of 10% or it may stop when reaching a goal SpO ₂ of 75%. Detailed charts (as shown in FIG. 4B) may be produced displaying the specific levels of SpO ₂ and oxygen content of the inhaled air during the test, for easier comparison over time and between specific test performances. The oxygen depletion tolerance test may also be referred to as the oxygen altitude test. The test may also show the associated altitude where that oxygen percentage occurs in nature rather than only showing the oxygen percentage of the inhaled air.

[0101] FIG. 5 illustrates an exemplary schematic block diagram of a computer platform for implementation of the system of FIG. 1.

[0102] With respect to FIG. 5, the computer system 500 can include an external storage device 510, a bus 520, a main memory 530, a read-only memory 540, a mass storage device 550, a communication port 560, and a processor 570. A person skilled in the art will appreciate that the computer system 500 may include more than one processor 570 and communication ports 360.

[0103] In an embodiment, the communication port 560 may be any of an RS-232 port for use with a modem-based dialup connection, a 10/100 Ethernet port, a Gigabit or 10 Gigabit port using copper or fiber, a serial port, a parallel port, or other existing or future ports. The communication port 560 may be chosen depending on a network, such a Local Area Network (LAN), Wide Area Network (WAN), or any network to which the computer system 500 connects.

[0104] In an embodiment, the memory 530 may be a Random Access Memory (RAM), or any other dynamic storage device commonly known in the art. The read-only memory 540 may be any static storage device(s) e.g., but not limited to, a Programmable Read Only Memory (PROM) chips for storing static information e.g., start-up or Basic Input/Output system (BIOS) instructions for the processor 570.

[0105] In an embodiment, the mass storage device 550 may be any current or future mass storage solution, which can be used to store information and/or instructions. Exemplary mass storage solutions include, but are not limited to, Parallel Advanced Technology Attachment (PATA) or Serial Advanced Technology Attachment (SATA) hard disk drives or solid-state drives (internal or external, e.g., having Universal Serial Bus (USB) and/or Firewire interfaces), one or more optical discs, Redundant Array of Independent Disks (RAID) storage, e.g., an array of disks (e.g., SATA arrays).

[0106] In an embodiment, the bus 520 communicatively couples the processor(s) 570 with the other memory, storage, and communication blocks. The bus 520 may be, e.g., a Peripheral Component Interconnect (PCI)/PCI Extended (PCLX) bus, Small Computer System Interface (SCSI), USB or the like, for connecting expansion cards, drives, and other subsystems as well as other buses, such a front side bus (FSB), which connects the processor 570 to computer system 500.

[0107] Optionally, operator and administrative interfaces, e.g., a display, keyboard, joystick, and a cursor control device, may also be coupled to the bus 520 to support direct operator interaction with the computer system 500. Other operator and administrative interfaces may be provided through network connections connected through the communication port 560. Components described above are meant only to exemplify various possibilities. In no way should the aforementioned exemplary computer system 500 limit the scope of the present disclosure.

[0108] It should be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the spirit of the appended claims. Moreover, in interpreting both the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. Where the specification claims refer to at least one of something selected from the group consisting of A, B, C ... .and N, the text should be interpreted as requiring only one element from the group, not A plus N, or B plus N, etc. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.

[0109] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions, or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.