Patent Application
20230149655
The present disclosure claims priority from Australia Provisional Patent Application Serial No. 2020901121, filed on 8 Apr. 2020, the entire disclosure of which is hereby incorporated herein by reference.
The present technology relates generally to methods and apparatus for treating respiratory disorders, such as those involving gas adsorption or controlled pressure swing adsorption. Such methodologies may be implemented in an oxygen concentrator. In some examples, the technology more specifically concerns such methods and apparatus for generating an oxygen therapy from a portable oxygen concentrator with multiple flow paths for implementing a hybrid mode where a flow of therapy gas has characteristic(s) (e.g., purity and/or flow rate) that may differ during inspiration (or part of inspiration) relative to non-inspiration times or expiration.
The respiratory system of the body facilitates gas exchange. The nose and mouth form the entrance to the airways of a patient.
The airways include a series of branching tubes, which become narrower, shorter and more numerous as they penetrate deeper into the lung. The prime function of the lung is gas exchange, allowing oxygen to move from the inhaled air into the venous blood and carbon dioxide to move in the opposite direction. The trachea divides into right and left main bronchi, which further divide eventually into terminal bronchioles. The bronchi make up the conducting airways, and do not take part in gas exchange. Further divisions of the airways lead to the respiratory bronchioles, and eventually to the alveoli. The alveolated region of the lung is where the gas exchange takes place, and is referred to as the respiratory zone. See “Respiratory Physiology”, by John B. West, Lippincott Williams & Wilkins, 9th edition published 2012.
A range of respiratory disorders exist. Examples of respiratory disorders include respiratory failure, Obesity Hyperventilation Syndrome (OHS), Chronic Obstructive Pulmonary Disease (COPD), Neuromuscular Disease (NMD) and Chest wall disorders.
Respiratory failure is an umbrella term for respiratory disorders in which the lungs are unable to inspire sufficient oxygen or exhale sufficient CO2 to meet the patient's needs. Respiratory failure may encompass some or all of the following disorders.
A patient with respiratory insufficiency (a form of respiratory failure) may experience abnormal shortness of breath on exercise.
Obesity Hyperventilation Syndrome (OHS) is defined as the combination of severe obesity and awake chronic hypercapnia, in the absence of other known causes for hypoventilation. Symptoms include dyspnea, morning headache and excessive daytime sleepiness.
Chronic Obstructive Pulmonary Disease (COPD) encompasses any of a group of lower airway diseases that have certain characteristics in common. These include increased resistance to air movement, extended expiratory phase of respiration, and loss of the normal elasticity of the lung. Examples of COPD are emphysema and chronic bronchitis. COPD is caused by chronic tobacco smoking (primary risk factor), occupational exposures, air pollution and genetic factors. Symptoms include: dyspnea on exertion, chronic cough and sputum production.
Neuromuscular Disease (NMD) is a broad term that encompasses many diseases and ailments that impair the functioning of the muscles either directly via intrinsic muscle pathology, or indirectly via nerve pathology. Some NMD patients are characterised by progressive muscular impairment leading to loss of ambulation, being wheelchair-bound, swallowing difficulties, respiratory muscle weakness and, eventually, death from respiratory failure. Neuromuscular disorders can be divided into rapidly progressive and slowly progressive. Rapidly progressive disorders are characterised by muscle impairment that worsens over months and results in death within a few years (e.g. Amyotrophic lateral sclerosis (ALS) and Duchenne muscular dystrophy (DMD) in teenagers). Variable or slowly progressive disorders are characterised by muscle impairment that worsens over years and only mildly reduces life expectancy (e.g. Limb girdle, Facioscapulohumeral and Myotonic muscular dystrophy). Symptoms of respiratory failure in NMD include: increasing generalised weakness, dysphagia, dyspnea on exertion and at rest, fatigue, sleepiness, morning headache, and difficulties with concentration and mood changes.
Chest wall disorders are a group of thoracic deformities that result in inefficient coupling between the respiratory muscles and the thoracic cage. The disorders are usually characterised by a restrictive defect and share the potential of long term hypercapnic respiratory failure. Scoliosis and/or kyphoscoliosis may cause severe respiratory failure. Symptoms of respiratory failure include: dyspnea on exertion, peripheral oedema, orthopnea, repeated chest infections, morning headaches, fatigue, poor sleep quality and loss of appetite.
In respiratory therapies known as “flow” therapies, the interface to the patient's airways is ‘open’ (unsealed) and the respiratory therapy may supplement the patient's own spontaneous breathing with a flow of conditioned or enriched air. In one example, High Flow therapy (HFT) is the provision of a continuous, heated, humidified flow of air to an entrance to the airway through an unsealed or open patient interface at a “treatment flow rate” that is held approximately constant throughout the respiratory cycle. The treatment flow rate is nominally set to exceed the patient's peak inspiratory flow rate.
Another form of flow therapy is long-term oxygen therapy (LTOT) or supplemental oxygen therapy. Doctors may prescribe a continuous flow of oxygen enriched air at a specified oxygen purity (from 21%, the oxygen fraction in ambient air, to 100%) at a specified flow rate (e.g., 1 litre per minute (LPM), 2 LPM, 3 LPM, etc.) to be delivered to the patient's airway.
Respiratory flow therapies may be provided by a respiratory therapy system or device. A respiratory therapy system as described herein may comprise an oxygen source, an air circuit, and a patient interface.
An air circuit is a conduit or a tube constructed and arranged to allow, in use, a flow of conditioned or enriched air to travel between two components of a respiratory therapy system such as the oxygen source and the patient interface.
A patient interface may be used to interface respiratory equipment to its wearer, for example by providing a flow of air to an entrance to the airways. The flow of air may be provided via a mask to the nose and/or mouth, a tube to the mouth or a tracheostomy tube to the trachea of a patient. For flow therapies such as nasal HFT or LTOT, the patient interface is configured to insufflate the nares but specifically to avoid a complete seal. One example of such a patient interface is a nasal cannula.
Experts in this field have recognized that exercise for respiratory failure patients provides long term benefits that slow the progression of the disease, improve quality of life and extend patient longevity. Most stationary forms of exercise like tread mills and stationary bicycles, however, are too strenuous for these patients. As a result, the need for mobility has long been recognized. Until recently, this mobility has been facilitated by the use of small compressed oxygen tanks or cylinders mounted on a cart with dolly wheels. The disadvantage of these tanks is that they contain a finite amount of oxygen and are heavy, weighing about 50 pounds when mounted.
Oxygen concentrators have been in use for about 50 years to supply oxygen for respiratory therapy. Oxygen concentrators may implement processes such as vacuum swing adsorption (VSA), pressure swing adsorption (PSA), or vacuum pressure swing adsorption (VPSA). For example, oxygen concentrators, e.g., POCs, may work based on depressurization (e.g., vacuum operation) and/or pressurization (e.g., compressor operation) in a swing adsorption process (e.g., Vacuum Swing Adsorption, Pressure Swing Adsorption or Vacuum Pressure Swing Adsorption, each of which are referred to herein as a “swing adsorption process”). Pressure swing adsorption may involve using one or more compressors to increase gas pressure inside one or more canisters that contains particles of a gas separation adsorbent. Such a canister when containing a mass of gas separation adsorbent such as a layer of gas separation adsorbent may serve as a sieve bed. As the pressure increases, certain molecules in the gas may become adsorbed onto the gas separation adsorbent. Removal of a portion of the gas in the canister under the pressurized conditions allows separation of the non-adsorbed molecules from the adsorbed molecules. The adsorbed molecules may then be desorbed by venting the sieve beds. Further details regarding oxygen concentrators may be found, for example, in U.S. Published Patent Application No. 2009-0065007, published Mar. 12, 2009, and entitled “Oxygen Concentrator Apparatus and Method”, which is incorporated herein by reference.
Ambient air usually includes approximately 78% nitrogen and 21% oxygen with the balance comprised of argon, carbon dioxide, water vapor and other trace gases. If a gas mixture such as air, for example, is passed under pressure through a canister containing a gas separation adsorbent that attracts nitrogen more strongly than it does oxygen, part or all of the nitrogen will stay in the canister, and the gas coming out of the canister will be enriched in oxygen. When the sieve bed reaches the end of its capacity to adsorb nitrogen, the adsorbed nitrogen may be desorbed by venting. The sieve bed is then ready for another cycle of producing oxygen enriched air. By alternating pressurization cycles of the canisters in a two-canister system, one canister can be separating oxygen while the other canister is being vented (resulting in a near-continuous separation of oxygen from the air). In this manner, oxygen enriched air can be accumulated, such as in a storage container or other pressurizable vessel or conduit coupled to the canisters, for a variety of uses including providing supplemental oxygen to users.
Vacuum swing adsorption (VSA) provides an alternative gas separation technique. VSA typically draws the gas through the separation process of the sieve beds using a vacuum such as a compressor configured to create a vacuum within the sieve beds. Vacuum Pressure Swing Adsorption (VPSA) may be understood to be a hybrid system using a combined vacuum and pressurization technique. For example, a VPSA system may pressurize the sieve beds for the separation process and also apply a vacuum for depressurizing the sieve beds.
Traditional oxygen concentrators have been bulky and heavy making ordinary ambulatory activities with them difficult and impractical. Recently, companies that manufacture large stationary oxygen concentrators began developing portable oxygen concentrators (POCs). The advantage of POCs is that they can produce a theoretically endless supply of oxygen and provide mobility for patients (users) during use. In order to make these devices small for mobility, the various systems necessary for the production of oxygen enriched air are condensed. POCs seek to utilize their produced oxygen as efficiently as possible, in order to minimise weight, size, and power consumption. In some implementations, this may be achieved by delivering the oxygen as series of pulses, each pulse or “bolus” timed to coincide with the onset of inhalation. This therapy mode is known as pulsed oxygen delivery (POD) or demand mode.
Continuous flow mode long-term oxygen therapy is advantageous for clinical reasons, e.g. reassuring patients they are receiving therapy, and relieving anxiety. However, continuous flow mode is draining of battery life and thus is more suitable for stationary devices. A need therefore exists for a portable oxygen concentrator capable of emulating the benefits of continuous flow mode with reasonable battery life.
Examples of the present technology may provide methods and apparatus for controlled operations of an oxygen concentrator, such as a portable oxygen concentrator. In particular, the technology provides methods and apparatus for a portable oxygen concentrator configured to deliver long-term oxygen therapy in a mode of delivery referred to herein as hybrid mode, while maintaining acceptable battery life. Hybrid mode therapy is a breath-synchronised therapy in which there is a non-zero inter-bolus flow of gas to the patient as well as boluses delivered in synchrony with inhalation as in POD mode. Hybrid mode therapy may be delivered according to a bilevel purity species, a bilevel flow rate species, or species intermediate between those two species.
All species of hybrid mode therapy present a challenge to traditional methods of detecting the onset of user inhalation. Examples of the present technology may therefore also include a sensor configuration that allows accurate detection of the onset of inhalation in the various sub-modes of hybrid mode therapy.
Some implementations of the present technology may include an oxygen concentrator for providing a therapy gas to a delivery conduit for patient inhalation. The oxygen concentrator may include a compressor configured to generate a pressurised air stream. The oxygen concentrator may include one or more sieve beds. The one or more sieve beds may include adsorbent material configured to preferentially adsorb a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The oxygen concentrator may include a valve set. The valve set may be configured to selectively pneumatically couple the compressor to the one or more sieve beds so as to selectively convey the pressurised air stream to the one or more sieve beds. The valve set may be configured to selectively vent exhaust gas to atmosphere from an exhaust outlet of the one or more sieve beds. The oxygen concentrator may include an accumulator pneumatically coupled to the one or more sieve beds so as to receive the oxygen enriched air produced from a product outlet of the one or more sieve beds. The oxygen concentrator may include a supply valve configured to selectively release oxygen enriched air from the accumulator via a primary flow path and then to the delivery conduit. The oxygen concentrator may include a secondary flow path configured to pass a portion of the exhaust gas from the exhaust outlet to the delivery conduit. The oxygen concentrator may include a controller operably coupled to the valve set and the supply valve. The controller may be configured to selectively actuate the valve set in a periodic pattern so as to produce oxygen enriched air for receiving by the accumulator and vent exhaust gas from the one or more sieve beds. The controller may be configured to selectively actuate the supply valve to release oxygen enriched air from the accumulator to the delivery conduit in synchrony with inhalation of the patient. The therapy gas may include the released oxygen enriched air and the portion of the exhaust gas.
In some implementations, the therapy gas may be provided to the delivery conduit in a hybrid mode wherein the therapy gas flows to the delivery conduit at least during patient inspiration and patient expiration. The hybrid mode may vary a characteristic of the therapy gas. The varied characteristic may be oxygen purity. The varied oxygen purity may include a first oxygen purity during at least a portion of patient inspiration and a second oxygen purity after the portion of patient inspiration. The first oxygen purity may be a purity in a range of about 50 percent to about 99 percent. The second oxygen purity may be a purity in a range of about 4 percent to 35 percent. The primary flow path may be configured to provide the therapy gas with the first oxygen purity. The secondary flow path may be configured to provide the therapy gas with the second oxygen purity. The secondary flow path may include a secondary valve configured to selectively release the portion of the exhaust gas to the delivery conduit. The controller may be further configured to selectively actuate the secondary valve in anti-sync with actuation of the supply valve to release the portion of the exhaust gas to the delivery conduit. The supply valve and the secondary valve may be implemented as a three-way valve configured to release either the oxygen enriched air or the portion of the exhaust gas to the delivery conduit.
In some implementations, the oxygen concentrator may further include a pressure sensor configured to generate a signal representative of a difference in pressure between a sense port and a reference port thereof, the sense port being connected to the delivery conduit, and the reference port being coupled to a flow path of the oxygen concentrator that may be downstream of the supply valve. The controller may be further configured to detect onset of inhalation from the generated pressure difference signal and to actuate the supply valve based on the detected onset of inhalation. The controller may be configured to detect onset of inhalation by detecting a drop in the generated pressure difference signal. The reference port of the pressure sensor may be connected to a downstream side of the supply valve via a flow restrictor. The controller may be configured to actuate the secondary valve in anti-sync with actuation of the supply valve in response to user activation of a control on an interface of the oxygen concentrator.
In some implementations, the oxygen concentrator may further include a flow restrictor within the secondary flow path and in line with the secondary valve. The flow restrictor may be configured such that a flow rate of exhaust gas when released to the delivery conduit may be approximately equal to a flow rate of the oxygen enriched air when released to the delivery conduit. The oxygen concentrator may include a further secondary valve configured to selectively release oxygen enriched air from the accumulator to the delivery conduit via a flow restrictor. The controller may be further configured to selectively actuate the further secondary valve in anti-sync with actuation of the supply valve to release oxygen enriched air to the delivery conduit. The hybrid mode may vary a further characteristic of the therapy gas. The varied further characteristic may be flow rate of the therapy gas.
Some implementations of the present technology may include apparatus for providing a therapy gas. The apparatus may include means for generating a pressurised air stream such as a motor operated compressor as described in more detail herein. The apparatus may include means for preferentially adsorbing a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream such as one or more sieve beds as described in more detail herein. The apparatus may include means for selectively pneumatically coupling, in a periodic pattern, the means for preferentially adsorbing with (a) the means for generating so as to selectively convey the pressurised air stream to the means for preferentially adsorbing, and (b) an exhaust outlet to atmosphere for selectively venting exhaust gas to atmosphere from the means for preferentially adsorbing, so as to produce oxygen enriched air within the means for preferentially adsorbing, such as a controller and a set of valves described in more detail herein. The apparatus may include means for accumulating the oxygen enriched air, such as an accumulator as described in more detail herein, produced from a product outlet of the means for preferentially adsorbing. The apparatus may include means for selectively releasing oxygen enriched air from the means for accumulating to a delivery conduit for a patient in synchrony with inhalation of the patient, such as a supply valve and a controller described in more detail herein. The apparatus may include means for passing a portion of the exhaust gas to the delivery conduit, such as a secondary flow path as described in more detail herein. The therapy gas may include the released oxygen enriched air from the means for accumulating and the portion of the exhaust gas.
Some implementations of the present technology may include an oxygen concentrator for producing a therapy gas for a patient. The oxygen concentrator may include a compressor configured to generate a pressurised air stream. The oxygen concentrator may include one or more sieve beds. The one or more sieve beds may include adsorbent material configured to preferentially adsorb a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The oxygen concentrator may include a valve set configured to selectively pneumatically couple the compressor to the one or more sieve beds so as to selectively convey the pressurised air stream to the one or more sieve beds. The oxygen concentrator may include an accumulator pneumatically coupled to the one or more sieve beds so as to receive the oxygen enriched air produced by one or more sieve beds. The oxygen concentrator may include a supply valve configured to selectively release oxygen enriched air from the accumulator, via a primary path, to a delivery conduit for the patient. The oxygen concentrator may include a secondary valve configured to selectively release oxygen enriched air from the accumulator, via a secondary path, to the delivery conduit for the patient. The oxygen concentrator may include a controller operably coupled to the valve, the supply valve, and the secondary valve. The controller may be configured to selectively actuate the valve set in a periodic pattern so as to produce oxygen enriched air in the accumulator. The controller may be configured to selectively actuate the supply valve to release oxygen enriched air to the delivery conduit in synchrony with inhalation of the patient. The controller may be configured to selectively actuate the secondary valve in anti-sync with actuation of the supply valve to release oxygen enriched air to the delivery conduit.
In some implementations, the therapy gas may be provided to the delivery conduit in a hybrid mode wherein the therapy gas flows to the delivery conduit at least during patient inspiration and patient expiration; and wherein the hybrid mode varies a characteristic of the therapy gas. The varied characteristic may be a flow rate of the therapy gas. The flow characteristic of the primary path may be different from a flow characteristic of the secondary path. The oxygen concentrator may further include a flow restrictor within the secondary path and in line with the secondary valve. The flow restrictor may be configured such that a flow rate of oxygen enriched air when released to the delivery conduit via the secondary valve may be substantially lower than a flow rate of the oxygen enriched air when released to the delivery conduit via the supply valve. The supply valve and the secondary valve may be implemented as a three-way valve configured to release oxygen enriched air to the delivery conduit.
In some implementations, the oxygen concentrator may further include a pressure sensor configured to generate a signal representative of a difference in pressure between a sense port and a reference port thereof. The sense port may be connected to the delivery conduit and the reference port may be coupled to a flow path of the oxygen concentrator that may be downstream of the supply valve. The controller may be further configured to detect onset of inhalation from the generated pressure difference signal and to actuate the supply valve based on the detected onset of inhalation. The controller may be configured to detect onset of inhalation by detecting a drop in the generated pressure difference signal. The reference port of the pressure sensor may be connected to a downstream side of the supply valve via a flow restrictor. The controller may be configured to actuate the secondary valve in anti-sync with actuation of the supply valve in response to user activation of a control on an interface of the oxygen concentrator. The oxygen concentrator may further include a further secondary valve configured to selectively release a portion of exhaust gas from the one or more sieve beds to the delivery conduit, wherein the controller may be further configured to selectively actuate the further secondary valve in anti-sync with actuation of the supply valve to release the portion of the exhaust gas to the delivery conduit. The hybrid mode may vary a further characteristic of the therapy gas. The varied further characteristic may be oxygen purity of the therapy gas.
Some implementations of the present technology may include apparatus. The apparatus may include means for generating a pressurised air stream. The apparatus may include means for preferentially adsorbing a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The apparatus may include means for selectively pneumatically coupling, in a periodic pattern, the means for preferentially adsorbing with the means for generating to selectively convey the pressurised air stream to the means for preferentially adsorbing so as to produce oxygen enriched air in the means for preferentially absorbing. The apparatus may include means for accumulating the oxygen enriched air produced by the means for preferentially adsorbing. The apparatus may include primary means for selectively releasing, in synchrony with inhalation of a patient, oxygen enriched air from the means for accumulating to a delivery conduit for the patient. The apparatus may include secondary means for selectively releasing, in anti-sync with actuation of the primary means for selectively releasing, oxygen enriched air from the means for accumulating to the delivery conduit for the patient.
Some implementations of the present technology may include an oxygen concentrator. The oxygen concentrator may include a compressor configured to generate a pressurised air stream. The apparatus may include one or more sieve beds. The one or more sieve beds may include adsorbent material configured to preferentially adsorb a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The apparatus may include a valve set configured to selectively pneumatically couple the compressor to the one or more sieve beds so as to selectively convey the pressurised air stream to the one or more sieve beds. The apparatus may include an accumulator pneumatically coupled to the one or more sieve beds so as to receive the oxygen enriched air produced by the one or more sieve beds. The apparatus may include a supply valve configured to selectively release oxygen enriched air from the accumulator to a delivery conduit for a patient. The apparatus may include a secondary path configured to convey a flow of gas to the delivery conduit for the patient. The apparatus may include a pressure sensor configured to generate a signal representative of a difference in pressure between a sense port and a reference port thereof. The sense port may be connected to the delivery conduit. The reference port may be coupled to a flow path of the oxygen concentrator that may be downstream of the supply valve. The apparatus may include a controller operably coupled to the valve set and the supply valve. The controller may be configured to selectively actuate the valve set in a periodic pattern so as to produce oxygen enriched air for the accumulator. The controller may be configured to detect onset of inhalation of the patient from the generated pressure difference signal. The controller may be configured to selectively actuate the supply valve to release oxygen enriched air to the delivery conduit in synchrony with inhalation of the patient.
In some implementations, the controller may be further configured to actuate the supply valve based on the detected onset of inhalation. The controller may be configured to detect onset of inhalation by detecting a drop in the generated pressure difference signal. The reference port of the pressure sensor may be connected to a downstream side of the supply valve via a flow restrictor. The secondary path may include a secondary valve configured to selectively release exhaust gas from the one or more sieve beds to the delivery conduit. The secondary path may further include a further secondary valve configured to selectively release oxygen enriched air from the accumulator to the delivery conduit via a flow restrictor. The secondary path may include a secondary valve configured to selectively release oxygen enriched air from the accumulator to the delivery conduit via a flow restrictor.
Some implementations of the present technology may include apparatus. The apparatus may include means for generating a pressurised air stream. The apparatus may include means for preferentially adsorbing a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The apparatus may include means for selectively pneumatically coupling, in a periodic pattern, the means for preferentially adsorbing with the means for generating so as to selectively convey the pressurised air stream to the means for preferentially adsorbing so as to produce oxygen enriched air in the means for preferentially absorbing. The apparatus may include means for accumulating the oxygen enriched air produced by the means for preferentially adsorbing. The apparatus may include means for selectively releasing oxygen enriched air from the means for accumulating to a delivery conduit for a patient. The apparatus may include secondary means for conveying a flow of gas to the delivery conduit for the patient. The apparatus may include means for generating a signal representative of a difference in pressure between a sense port and a reference port thereof. The sense port may be connected to the delivery conduit. The apparatus may include means for detecting onset of inhalation of the patient from the generated pressure difference signal and for selectively actuating the means for selectively releasing oxygen enriched air to release oxygen enriched air to the delivery conduit in synchrony with inhalation of the patient.
Another general aspect includes an oxygen concentrator. The oxygen concentrator includes a compressor configured to generate a pressurised air stream. The oxygen concentrator also includes at least one sieve bed, the or each each sieve bed including adsorbent material configured to preferentially adsorb a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The oxygen concentrator also includes a valve configured to: selectively pneumatically couple the compressor to the or each sieve bed so as to selectively convey the pressurised air stream to the sieve bed, and selectively vent exhaust gas from the or each sieve bed. The oxygen concentrator also includes an accumulator pneumatically coupled to the or each sieve bed so as to receive the oxygen enriched air produced by the or each sieve bed. The oxygen concentrator also includes a supply valve configured to selectively release oxygen enriched air from the accumulator to a patient via a delivery conduit. The oxygen concentrator also includes a secondary valve configured to selectively release a portion of the exhaust gas to the delivery conduit. The oxygen concentrator also includes a controller operably coupled to the valve, the supply valve, and the secondary valve, the controller configured to: selectively actuate the valve in a periodic pattern so as to produce oxygen enriched air in the accumulator, selectively actuate the supply valve to release oxygen enriched air to the delivery conduit in synchrony with inhalation of the patient, and selectively actuate the secondary valve in anti-sync with actuation of the supply valve to release the portion of the exhaust gas to the delivery conduit.
One general aspect includes apparatus. The apparatus also includes means for generating a pressurised air stream. The apparatus also includes means for preferentially adsorbing a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The apparatus also includes means for selectively pneumatically coupling the means for generating to the means for preferentially adsorbing so as to selectively convey the pressurised air stream to the means for preferentially adsorbing. The apparatus also includes means for selectively venting exhaust gas from the means for preferentially adsorbing. The apparatus also includes means for receiving the oxygen enriched air produced by the means for preferentially adsorbing. The apparatus also includes means for selectively releasing oxygen enriched air from the means for receiving to a patient via a delivery conduit. The apparatus also includes means for selectively releasing a portion of the exhaust gas to the delivery conduit. The apparatus also includes means for selectively actuating the means for selectively pneumatically coupling in a periodic pattern so as to produce oxygen enriched air in the means for receiving. The apparatus also includes means for selectively actuating the means for selectively releasing oxygen enriched air to release oxygen enriched air to the delivery conduit in synchrony with inhalation of the patient. The apparatus also includes means for selectively actuating the means for selectively releasing exhaust gas in anti-sync with actuation of the means for selectively releasing oxygen enriched air to release the portion of the exhaust gas to the delivery conduit.
One general aspect includes an oxygen concentrator. The oxygen concentrator also includes a compressor configured to generate a pressurised air stream. The oxygen concentrator also includes at least one sieve bed, the or each each sieve bed including adsorbent material configured to preferentially adsorb a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The oxygen concentrator also includes a valve configured to selectively pneumatically couple the compressor to the or each sieve bed so as to selectively convey the pressurised air stream to the sieve bed. The oxygen concentrator also includes an accumulator pneumatically coupled to the or each sieve bed so as to receive the oxygen enriched air produced by the or each sieve bed. The oxygen concentrator also includes a supply valve configured to selectively release oxygen enriched air from the accumulator to a patient via a delivery conduit. The oxygen concentrator also includes a secondary valve configured to selectively release oxygen enriched air from the accumulator to the patient via the delivery conduit. The oxygen concentrator also includes a controller operably coupled to the valve, the supply valve, and the secondary valve, the controller configured to: selectively actuate the valve in a periodic pattern so as to produce oxygen enriched air in the accumulator, selectively actuate the supply valve to release oxygen enriched air to the delivery conduit in synchrony with inhalation of the patient, and selectively actuate the secondary valve in anti-sync with actuation of the supply valve to release oxygen enriched air to the delivery conduit.
One general aspect includes apparatus. The apparatus also includes means for generating a pressurised air stream. The apparatus also includes means for preferentially adsorbing a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The apparatus also includes means for selectively pneumatically coupling the means for generating to the means for preferentially adsorbing so as to selectively convey the pressurised air stream to the means for preferentially adsorbing. The apparatus also includes means for receiving the oxygen enriched air produced by the means for preferentially adsorbing. The apparatus also includes means for selectively releasing oxygen enriched air from the means for receiving to a patient via a delivery conduit. The apparatus also includes secondary means for selectively releasing oxygen enriched air from the means for receiving to a patient via a delivery conduit. The apparatus also includes means for selectively actuating the means for selectively pneumatically coupling in a periodic pattern so as to produce oxygen enriched air in the means for receiving. The apparatus also includes means for selectively actuating the means for selectively releasing oxygen enriched air to release oxygen enriched air to the delivery conduit in synchrony with inhalation of the patient. The apparatus also includes means for selectively actuating the secondary means for selectively releasing oxygen enriched air in anti-sync with actuation of the means for selectively releasing oxygen enriched air to release oxygen enriched air to the delivery conduit.
One general aspect includes an oxygen concentrator. The oxygen concentrator also includes a compressor configured to generate a pressurised air stream. The oxygen concentrator also includes at least one sieve bed, the or each each sieve bed including adsorbent material configured to preferentially adsorb a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The oxygen concentrator also includes a valve configured to selectively pneumatically couple the compressor to the or each sieve bed so as to selectively convey the pressurised air stream to the sieve bed. The oxygen concentrator also includes an accumulator pneumatically coupled to the or each sieve bed so as to receive the oxygen enriched air produced by the or each sieve bed. The oxygen concentrator also includes a supply valve configured to selectively release oxygen enriched air from the accumulator to a patient via a delivery conduit. The oxygen concentrator also includes a secondary path configured to convey a flow of gas to the patient via the delivery conduit. The oxygen concentrator also includes a pressure sensor configured to generate a signal representative of a difference in pressure between a sense port and a reference port thereof, the sense port being connected to the delivery conduit. The oxygen concentrator also includes a controller operably coupled to the valve and the supply valve, the controller configured to: selectively actuate the valve in a periodic pattern so as to produce oxygen enriched air in the accumulator, detect onset of inhalation of the patient from the generated pressure difference signal, and selectively actuate the supply valve to release oxygen enriched air to the delivery conduit in synchrony with inhalation of the patient.
One general aspect includes apparatus. The apparatus also includes means for generating a pressurised air stream. The apparatus also includes means for preferentially adsorbing a component gas from the pressurised air stream, thereby producing oxygen enriched air from the pressurised air stream. The apparatus also includes means for selectively pneumatically coupling the means for generating to the means for preferentially adsorbing so as to selectively convey the pressurised air stream to the means for preferentially adsorbing. The apparatus also includes means for receiving the oxygen enriched air produced by the means for preferentially adsorbing. The apparatus also includes means for selectively releasing oxygen enriched air from the means for receiving to a patient via a delivery conduit. The apparatus also includes means for conveying a flow of gas to the patient via the delivery conduit. The apparatus also includes means for generating a signal representative of a difference in pressure between a sense port and a reference port thereof, the sense port being connected to the delivery conduit. The apparatus also includes means for selectively actuating the means for selectively pneumatically coupling in a periodic pattern so as to produce oxygen enriched air in the means for receiving. The apparatus also includes means for detecting onset of inhalation of the patient from the generated pressure difference signal. The apparatus also includes means for selectively actuating the means for selectively releasing oxygen enriched air to release oxygen enriched air to the delivery conduit in synchrony with inhalation of the patient.
Of course, portions of the aspects may form sub-aspects of the present technology. Also, various ones of the sub-aspects and/or aspects may be combined in various manners and also constitute additional aspects or sub-aspects of the present technology.
Other features of the technology will be apparent from consideration of the information contained in the following detailed description, abstract, drawings and claims.
Advantages of the present technology will become apparent to those skilled in the art with the benefit of the following detailed description of implementations and upon reference to the accompanying drawings in which similar reference numerals indicate similar components:
Examples implementations of the present disclosure are described in detail with reference to the drawing figures wherein like reference numerals identify similar or identical elements. It is to be understood that the disclosed embodiments are merely examples of the disclosure, which may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure.
Oxygen concentrator 100 may be a portable oxygen concentrator. For example, oxygen concentrator 100 may have a weight and size that allows the oxygen concentrator to be carried by hand and/or in a carrying case during use. As discussed further herein, such a device typically operates with an included power supply that provides power to the oxygen concentrator using one or more batteries, such as Lithium ion batteries, which are typically rechargeable. In one implementation, oxygen concentrator 100 has a weight of less than about 20 pounds, less than about 15 pounds, less than about 10 pounds, or less than about 5 pounds. In an implementation, oxygen concentrator 100 has a volume of less than about 1000 cubic inches, less than about 750 cubic inches, less than about 500 cubic inches, less than about 250 cubic inches, or less than about 200 cubic inches.
Oxygen enriched air may be produced from ambient air by pressurising ambient air in canisters 302 and 304, which contain a gas separation adsorbent and are therefore referred to as sieve beds. Gas separation adsorbents useful in an oxygen concentrator are capable of separating at least nitrogen from an air stream to produce oxygen enriched air. Examples of gas separation adsorbents include molecular sieves that are capable of separating nitrogen from an air stream. Examples of adsorbents that may be used in an oxygen concentrator include, but are not limited to, zeolites (natural) or synthetic crystalline aluminosilicates that separate nitrogen from an air stream under elevated pressure. Examples of synthetic crystalline aluminosilicates that may be used include, but are not limited to: OXYSIV adsorbents available from UOP LLC, Des Plaines, IW; SYLOBEAD adsorbents available from W. R. Grace & Co, Columbia, Md.; SILIPORITE adsorbents available from CECA S.A. of Paris, France; ZEOCHEM adsorbents available from Zeochem AG, Uetikon, Switzerland; and AgLiLSX adsorbent available from Air Products and Chemicals, Inc., Allentown, Pa.
As shown in
Compression system 200 may include one or more compressors configured to compress air. Pressurized air, produced by compression system 200, may be forced into one or both of the canisters 302 and 304. In some implementations, the ambient air may be pressurized in the canisters to a pressure approximately in a range of 13-20 pounds per square inch gauge pressure (psig). Other pressures may also be used, depending on the type of gas separation adsorbent disposed in the canisters.
The oxygen concentrator may typically include a valve set of one more valves for directing the pressurized air for the processes of the oxygen concentrator so as to produce the oxygen enriched air. For example, coupled to each canister 302/304 are inlet valves 122/124 and outlet valves 132/134. As shown in
In some implementations, a two-step valve actuation voltage may be generated to control inlet valves 122/124 and outlet valves 132/134. For example, a high voltage (e.g., 24 V) may be applied to an inlet valve to open the inlet valve. The voltage may then be reduced (e.g., to 7 V) to keep the inlet valve open. Using less voltage to keep a valve open may use less power (Power=Voltage*Current). This reduction in voltage minimizes heat buildup and power consumption to extend run time from the power supply 180 (described below). When the power is cut off to the valve, it closes by spring action. In some implementations, the voltage may be applied as a function of time that is not necessarily a stepped response (e.g., a curved downward voltage between an initial 24 V and a final 7 V).
In an implementation, pressurized air is sent into one of canisters 302 or 304 while the other canister is being vented. For example, during use, inlet valve 122 is opened while inlet valve 124 is closed. Pressurized air from compression system 200 is forced into canister 302, while being inhibited from entering canister 304 by inlet valve 124. In an implementation, a controller 400 is electrically coupled to valves 122, 124, 132, and 134. Controller 400 includes one or more processors 410 operable to execute program instructions stored in memory 420. The program instructions configure the controller to perform various predefined methods that are used to operate the oxygen concentrator, such as the methods described in more detail herein. The program instructions may include program instructions for operating inlet valves 122 and 124 out of phase with each other, i.e., when one of inlet valves 122 or 124 is opened, the other valve is closed. During pressurization of canister 302, outlet valve 132 is closed and outlet valve 134 is opened. Similar to the inlet valves, outlet valves 132 and 134 are operated out of phase with each other. In some implementations, the voltages and the durations of the voltages used to open the input and output valves may be controlled by controller 400. The controller 400 may include a transceiver 430 that may communicate with external devices to transmit data collected by the processor 410 or receive instructions from an external device for the processor 410.
Check valves 142 and 144 are coupled to canisters 302 and 304, respectively. Check valves 142 and 144 may be one-way valves that are passively operated by the pressure differentials that occur as the canisters are pressurized and vented, or may be active valves. Check valves 142 and 144 are coupled to the canisters to allow oxygen enriched air produced during pressurization of each canister to flow out of the canister, and to inhibit back flow of oxygen enriched air or any other gases into the canister. In this manner, check valves 142 and 144 act as one-way valves allowing oxygen enriched air to exit the respective canisters during pressurization.
The term “check valve”, as used herein, refers to a valve that allows flow of a fluid (gas or liquid) in one direction and inhibits back flow of the fluid. Examples of check valves that are suitable for use include, but are not limited to: a ball check valve; a diaphragm check valve; a butterfly check valve; a swing check valve; a duckbill valve; an umbrella valve; and a lift check valve. Under pressure, nitrogen molecules in the pressurized ambient air are adsorbed by the gas separation adsorbent in the pressurized canister. As the pressure increases, more nitrogen is adsorbed until the gas in the canister is enriched in oxygen. The nonadsorbed gas molecules (mainly oxygen) flow out of the pressurized canister when the pressure reaches a point sufficient to overcome the resistance of the check valve coupled to the canister. In one implementation, the pressure drop of the check valve in the forward direction is less than 1 psi. The break pressure in the reverse direction is greater than 100 psi. It should be understood, however, that modification of one or more components would alter the operating parameters of these valves. If the forward flow pressure is increased, there is, generally, a reduction in oxygen enriched air production. If the break pressure for reverse flow is reduced or set too low, there is, generally, a reduction in oxygen enriched air pressure.
In an exemplary implementation, canister 302 is pressurized by compressed air produced in compression system 200 and passed into canister 302. During pressurization of canister 302 inlet valve 122 is open, outlet valve 132 is closed, inlet valve 124 is closed and outlet valve 134 is open. Outlet valve 134 is opened when outlet valve 132 is closed to allow substantially simultaneous venting of canister 304 to atmosphere via the canister's exhaust outlet while canister 302 is being pressurized. Canister 302 is pressurized until the pressure in canister is sufficient to open check valve 142. Oxygen enriched air produced in canister 302 exits from the canister's product outlet and passes through a check valve and, in one implementation, is collected in accumulator 106.
After some time, the gas separation adsorbent will become saturated with nitrogen and will be unable to separate significant amounts of nitrogen from incoming air. This point is usually reached after a predetermined time of oxygen enriched air production. In the implementation described above, when the gas separation adsorbent in canister 302 reaches this saturation point, the inflow of compressed air is stopped and canister 302 is vented to desorb nitrogen. During venting, inlet valve 122 is closed, and outlet valve 132 is opened. While canister 302 is being vented, canister 304 is pressurized to produce oxygen enriched air in the same manner described above. Pressurization of canister 304 is achieved by closing outlet valve 134 and opening inlet valve 124. The oxygen enriched air exits canister 304 through check valve 144.
During venting of canister 302 from its exhaust outlet, outlet valve 132 may be opened allowing exhaust gas to exit the canister to atmosphere through concentrator outlet 130. In an implementation, the vented exhaust gas may be directed through muffler 133 to reduce the noise produced by releasing the pressurized gas from the canister. As gas is released from canister 302, the pressure in the canister 302 drops, allowing nitrogen to become desorbed from the gas separation adsorbent. The vented exhaust gas exits the oxygen concentrator through outlet 130, resetting the canister to a state that allows renewed separation of nitrogen from an air stream. Muffler 133 may include open cell foam (or another material) to muffle the sound of the gas leaving the oxygen concentrator. In some implementations, the combined muffling components/techniques for the input of air and the output of oxygen enriched air may provide for oxygen concentrator operation at a sound level below 50 decibels.
During venting of the canisters, it is advantageous that at least a majority of the nitrogen is removed. In an implementation, at least about 50%, at least about 60%, at least about 70%, at least about 80%, at least about 90%, at least about 95%, at least about 98%, or substantially all of the nitrogen in a canister is removed before the canister is re-used to separate nitrogen from air. In some implementations, nitrogen removal may be assisted using an oxygen enriched air stream that is introduced into the canister from the other canister or stored oxygen enriched air.
In an exemplary implementation, a portion of the oxygen enriched air may be transferred from canister 302 to canister 304 when canister 304 is being vented of exhaust gas. Transfer of oxygen enriched air from canister 302 to canister 304 during venting of canister 304 helps to desorb nitrogen from the adsorbent by lowering the partial pressure of nitrogen adjacent the adsorbent. The flow of oxygen enriched air also helps to purge desorbed nitrogen (and other gases) from the canister. In an implementation, oxygen enriched air may travel through flow restrictors 151, 153, and 155 between the two canisters. Flow restrictor 151 may be a trickle flow restrictor. Flow restrictor 151, for example, may be a 0.009D flow restrictor (e.g., the flow restrictor has a radius 0.009″ which is less than the diameter of the tube it is inside). Flow restrictors 153 and 155 may be 0.013D flow restrictors. Other flow restrictor types and sizes are also contemplated and may be used depending on the specific configuration and tubing used to couple the canisters. In some implementations, the flow restrictors may be press fit flow restrictors that restrict air flow by introducing a narrower diameter in their respective tube. In some implementations, the press fit flow restrictors may be made of sapphire, metal or plastic (other materials are also contemplated).
Flow of oxygen enriched air between the canisters is also controlled by use of valve 152 and valve 154. Valves 152 and 154 may be opened for a short duration during the venting process (and may be closed otherwise) to prevent excessive oxygen loss out of the purging canister. Other durations are also contemplated. In an exemplary implementation, canister 302 is being vented and it is desirable to purge canister 302 by passing a portion of the oxygen enriched air being produced in canister 304 into canister 302. A portion of oxygen enriched air, upon pressurization of canister 304, will pass through flow restrictor 151 into canister 302 during venting of canister 302. Additional oxygen enriched air is passed into canister 302, from canister 304, through valve 154 and flow restrictor 155. Valve 152 may remain closed during the transfer process, or may be opened if additional oxygen enriched air is needed. The selection of appropriate flow restrictors 151 and 155, coupled with controlled opening of valve 154 allows a controlled amount of oxygen enriched air to be sent from canister 304 to canister 302. In an implementation, the controlled amount of oxygen enriched air is an amount sufficient to purge canister 302 and minimize the loss of oxygen enriched air through venting valve 132 of canister 302. While this implementation describes venting of canister 302, it should be understood that the same process can be used to vent canister 304 using flow restrictor 151, valve 152 and flow restrictor 153.
The pair of equalization/vent valves 152/154 work with flow restrictors 153 and 155 to optimize the gas flow balance between the two canisters. This may allow for better flow control for venting one of the canisters with oxygen enriched air from the other of the canisters. It may also provide better flow direction between the two canisters. It has been found that, while flow valves 152/154 may be operated as bi-directional valves, the flow rate through such valves varies depending on the direction of fluid flowing through the valve. For example, oxygen enriched air flowing from canister 304 toward canister 302 has a flow rate faster through valve 152 than the flow rate of oxygen enriched air flowing from canister 302 toward canister 304 through valve 152. If a single valve was to be used, eventually either too much or too little oxygen enriched air would be sent between the canisters and the canisters would, over time, begin to produce different amounts of oxygen enriched air. Use of opposing valves and flow restrictors on parallel air pathways may equalize the flow pattern of the oxygen enriched air between the two canisters. Equalising the flow may allow for a steady amount of oxygen enriched air to be available to the user over multiple cycles and also may allow a predictable volume of oxygen enriched air to purge the other of the canisters. In some implementations, the air pathway may not have restrictors but may instead have a valve with a built-in resistance or the air pathway itself may have a narrow radius to provide resistance.
At times, oxygen concentrator may be shut down for a period of time. When an oxygen concentrator is shut down, the temperature inside the canisters may drop as a result of the loss of adiabatic heat from the compression system. As the temperature drops, the volume occupied by the gases inside the canisters will drop. Cooling of the canisters may lead to a negative pressure in the canisters. Valves (e.g., valves 122, 124, 132, and 134) leading to and from the canisters are dynamically sealed rather than hermetically sealed. Thus, outside air may enter the canisters after shutdown to accommodate the pressure differential. When outside air enters the canisters, moisture from the outside air may be adsorbed by the gas separation adsorbent. Adsorption of water inside the canisters may lead to gradual degradation of the gas separation adsorbents, steadily reducing ability of the gas separation adsorbents to produce oxygen enriched air.
In an implementation, outside air may be inhibited from entering canisters after the oxygen concentrator is shut down by pressurising both canisters prior to shutdown. By storing the canisters under a positive pressure, the valves may be forced into a hermetically closed position by the internal pressure of the air in the canisters. In an implementation, the pressure in the canisters, at shutdown, should be at least greater than ambient pressure. As used herein the term “ambient pressure” refers to the pressure of the surroundings in which the oxygen concentrator is located (e.g. the pressure inside a room, outside, in a plane, etc.). In an implementation, the pressure in the canisters, at shutdown, is at least greater than standard atmospheric pressure (i.e., greater than 760 mmHg (Torr), 1 atm, 101,325 Pa). In an implementation, the pressure in the canisters, at shutdown, is at least about 1.1 times greater than ambient pressure; is at least about 1.5 times greater than ambient pressure; or is at least about 2 times greater than ambient pressure.
In an implementation, pressurization of the canisters may be achieved by directing pressurized air into each canister from the compression system and closing all valves to trap the pressurized air in the canisters. In an exemplary implementation, when a shutdown sequence is initiated, inlet valves 122 and 124 are opened and outlet valves 132 and 134 are closed. Because inlet valves 122 and 124 are joined together by a common conduit, both canisters 302 and 304 may become pressurized as air and/or oxygen enriched air from one canister may be transferred to the other canister. This situation may occur when the pathway between the compression system and the two inlet valves allows such transfer. Because the oxygen concentrator operates in an alternating pressurize/venting mode, at least one of the canisters should be in a pressurized state at any given time. In an alternate implementation, the pressure may be increased in each canister by operation of compression system 200. When inlet valves 122 and 124 are opened, pressure between canisters 302 and 304 will equalize, however, the equalized pressure in either canister may not be sufficient to inhibit air from entering the canisters during shutdown. In order to ensure that air is inhibited from entering the canisters, compression system 200 may be operated for a time sufficient to increase the pressure inside both canisters to a level at least greater than ambient pressure. Regardless of the method of pressurization of the canisters, once the canisters are pressurized, inlet valves 122 and 124 are closed, trapping the pressurized air inside the canisters, which inhibits air from entering the canisters during the shutdown period.
Referring to
In some implementations, compression system 200 includes one or more compressors. In another implementation, compression system 200 includes a single compressor, coupled to all of the canisters of canister system 300. Turning to
In one implementation, compressor 210 includes a single head wobble type compressor having a piston. Other types of compressors may be used such as diaphragm compressors and other types of piston compressors. Motor 220 may be a DC or AC motor and provides the operating power to the compressing component of compressor 210. Motor 220, in an implementation, may be a brushless DC motor. Motor 220 may be a variable speed motor configured to operate the compressing component of compressor 210 at variable speeds. Motor 220 may be coupled to controller 400, as depicted in
Compression system 200 inherently creates substantial heat. Heat is caused by the consumption of power by motor 220 and the conversion of power into mechanical motion. Compressor 210 generates heat due to the increased resistance to movement of the compressor components by the air being compressed. Heat is also inherently generated due to adiabatic compression of the air by compressor 210. Thus, the continual pressurization of air produces heat in the enclosure. Additionally, power supply 180 may produce heat as power is supplied to compression system 200. Furthermore, users of the oxygen concentrator may operate the device in unconditioned environments (e.g., outdoors) at potentially higher ambient temperatures than indoors, thus the incoming air will already be in a heated state.
Heat produced inside oxygen concentrator 100 can be problematic. Lithium ion batteries are generally employed as power supplies for oxygen concentrators due to their long life and light weight. Lithium ion battery packs, however, are dangerous at elevated temperatures and safety controls are employed in oxygen concentrator 100 to shutdown the system if dangerously high power supply temperatures are detected. Additionally, as the internal temperature of oxygen concentrator 100 increases, the amount of oxygen generated by the concentrator may decrease. This is due, in part, to the decreasing amount of oxygen in a given volume of air at higher temperatures. If the amount of produced oxygen drops below a predetermined amount, the oxygen concentrator 100 may automatically shut down.
Because of the compact nature of oxygen concentrators, dissipation of heat can be difficult. Solutions typically involve the use of one or more fans to create a flow of cooling air through the enclosure. Such solutions, however, require additional power from the power supply 180 and thus shorten the portable usage time of the oxygen concentrator. In an implementation, a passive cooling system may be used that takes advantage of the mechanical power produced by motor 220. Referring to
Moreover, an external rotating armature may help the efficiency of the motor, allowing less heat to be generated. A motor having an external armature operates similar to the way a flywheel works in an internal combustion engine. When the motor is driving the compressor, the resistance to rotation is low at low pressures. When the pressure of the compressed air is higher, the resistance to rotation of the motor is higher. As a result, the motor does not maintain consistent ideal rotational stability, but instead surges and slows down depending on the pressure demands of the compressor. This tendency of the motor to surge and then slow down is inefficient and therefore generates heat. Use of an external armature adds greater angular momentum to the motor which helps to compensate for the variable resistance experienced by the motor. Since the motor does not have to work as hard, the heat produced by the motor may be reduced.
In an implementation, cooling efficiency may be further increased by coupling an air transfer device 240 to external rotating armature 230. In an implementation, air transfer device 240 is coupled to the external armature 230 such that rotation of the external armature 230 causes the air transfer device 240 to create an air flow that passes over at least a portion of the motor. In an implementation, air transfer device 240 includes one or more fan blades coupled to the external armature 230. In an implementation, a plurality of fan blades may be arranged in an annular ring such that the air transfer device 240 acts as an impeller that is rotated by movement of the external rotating armature 230. As depicted in
Further, referring to
In an implementation, the compressor outlet conduit 250 is composed of a heat exchange metal. Heat exchange metals include, but are not limited to, aluminum, carbon steel, stainless steel, titanium, copper, copper-nickel alloys or other alloys formed from combinations of these metals. Thus, compressor outlet conduit 250 can act as a heat exchanger to remove heat that is inherently caused by compression of the air. By removing heat from the compressed air, the number of molecules in a given volume at a given pressure is increased. As a result, the amount of oxygen enriched air that can be generated by each canister during each pressure swing cycle may be increased.
The heat dissipation mechanisms described herein are either passive or make use of elements required for the oxygen concentrator 100. Thus, for example, dissipation of heat may be increased without using systems that require additional power. By not requiring additional power, the run-time of the battery packs may be increased and the size and weight of the oxygen concentrator may be minimized. Likewise, use of an additional box fan or cooling unit may be eliminated. Eliminating such additional features reduces the weight and power consumption of the oxygen concentrator.
As discussed above, adiabatic compression of air causes the air temperature to increase. During venting of a canister in canister system 300, the pressure of the gas being released from the canisters decreases. The adiabatic decompression of the gas in the canister causes the temperature of the gas to drop as it is vented. In an implementation, the cooled exhaust gases 327 vented from canister system 300 are directed toward power supply 180 and toward compression system 200. In an implementation, base 315 of canister system 300 receives the exhaust gases from the canisters. The exhaust gases 327 are directed through base 315 toward outlet 325 of the base and toward power supply 180. The exhaust gases, as noted, are cooled due to decompression of the gases and therefore passively provide cooling to the power supply 180. When the compression system is operated, the air transfer device 240 will gather the cooled exhaust gas and direct the exhaust gas toward the motor of compression system 200. Fan 172 may also assist in directing the exhaust gas across compression system 200 and out of the housing 170. In this manner, additional cooling may be obtained without requiring any further power from the battery.
Oxygen concentrator 100 may include at least two canisters, each canister including a gas separation adsorbent. The canisters of oxygen concentrator 100 may be disposed formed from a molded housing. In an implementation, canister system 300 includes two housing components 310 and 510, as depicted in
As shown, valve seats 322, 324, 332, and 334 and air pathways 330 and 346 may be integrated into the housing component 310 to reduce the number of sealed connections needed throughout the air flow of the oxygen concentrator 100.
Air pathways/tubing between different sections in housing components 310 and 510 may take the form of molded conduits. Conduits in the form of molded channels for air pathways may occupy multiple planes in housing components 310 and 510. For example, the molded air conduits may be formed at different depths and at different x,y,z positions in housing components 310 and 510. In some implementations, a majority or substantially all of the conduits may be integrated into the housing components 310 and 510 to reduce potential leak points.
In some implementations, prior to coupling housing components 310 and 510 together, O-rings may be placed between various points of housing components 310 and 510 to ensure that the housing components are properly sealed. In some implementations, components may be integrated and/or coupled separately to housing components 310 and 510. For example, tubing, flow restrictors (e.g., press fit flow restrictors), oxygen sensors, gas separation adsorbents, check valves, plugs, processors, power supplies, etc. may be coupled to housing components 310 and 510 before and/or after the housing components are coupled together.
In some implementations, apertures 337 leading to the exterior of housing components 310 and 510 may be used to insert devices such as flow restrictors. Apertures may also be used for increased moldability. One or more of the apertures may be plugged after molding (e.g., with a plastic plug). In some implementations, flow restrictors may be inserted into passages prior to inserting plugs to seal the passages. Press fit flow restrictors may have diameters that may allow a friction fit between the press fit flow restrictors and their respective apertures. In some implementations, an adhesive may be added to the exterior of the press fit flow restrictors to hold the press fit flow restrictors in place once inserted. In some implementations, the plugs may have a friction fit with their respective tubes (or may have an adhesive applied to their outer surface). The press fit flow restrictors and/or other components may be inserted and pressed into their respective apertures using a narrow tip tool or rod (e.g., with a diameter less than the diameter of the respective aperture). In some implementations, the press fit flow restrictors may be inserted into their respective tubes until they abut a feature in the tube to halt their insertion. For example, the feature may include a reduction in radius. Other features are also contemplated (e.g., a bump in the side of the tubing, threads, etc.). In some implementations, press fit flow restrictors may be molded into the housing components (e.g., as narrow tube segments).
In some implementations, spring baffle 139 may be placed into respective canister receiving portions of housing components 310 and 510 with the spring side of the baffle 139 facing the exit of the canister. Spring baffle 139 may apply force to gas separation adsorbent in the canister while also assisting in preventing gas separation adsorbent from entering the exit apertures. Use of a spring baffle 139 may keep the gas separation adsorbent compact while also allowing for expansion (e.g., thermal expansion). Keeping the gas separation adsorbent compact may prevent the gas separation adsorbent from breaking during movement of the oxygen concentrator 100.
In some implementations, filter 129 may be placed into respective canister receiving portions of housing components 310 and 510 facing the inlet of the respective canisters. The filter 129 removes particles from the feed gas stream entering the canisters.
In some implementations, pressurized air from the compression system 200 may enter air inlet 306. Air inlet 306 is coupled to inlet conduit 330. Air enters housing component 310 through inlet 306 and travels through inlet conduit 330, and then to valve seats 322 and 324.
In an implementation, pressurized air is sent into one of canisters 302 or 304 while the other canister is being vented. For example, during use, inlet valve 122 is opened while inlet valve 124 is closed. Pressurized air from compression system 200 is forced into canister 302, while being inhibited from entering canister 304 by inlet valve 124. During pressurization of canister 302, outlet valve 132 is closed and outlet valve 134 is opened. Similar to the inlet valves, outlet valves 132 and 134 are operated out of phase with each other. Valve seat 322 includes an opening 323 that passes through housing component 310 into canister 302. Similarly valve seat 324 includes an opening 375 that passes through housing component 310 into canister 302. Air from inlet conduit 330 passes through openings 323 or 375 if the respective valves 122 and 124 are open, and enters a canister.
Check valves 142 and 144 (See
Oxygen enriched air from either canister travels through conduit 342 or 344 and enters conduit 346 formed in housing component 310. Conduit 346 includes openings that couple the conduit to conduit 342, conduit 344 and accumulator 106. Thus, oxygen enriched air, produced in canister 302 or 304, travels to conduit 346 and passes into accumulator 106. As illustrated in
After some time, the gas separation adsorbent will become saturated with nitrogen and will be unable to separate significant amounts of nitrogen from incoming air. When the gas separation adsorbent in a canister reaches this saturation point, the inflow of compressed air is stopped and the canister is vented to desorb nitrogen from the adsorbent. Canister 302 is vented by closing inlet valve 122 and opening outlet valve 132. Outlet valve 132 releases the exhaust gas from canister 302 into the volume defined by the end of housing component 310. Foam material may cover the end of housing component 310 to reduce the sound made by release of gases from the canisters. Similarly, canister 304 is vented by closing inlet valve 124 and opening outlet valve 134. Outlet valve 134 releases the exhaust gas from canister 304 into the volume defined by the end of housing component 310.
While canister 302 is being vented, canister 304 is pressurized to produce oxygen enriched air in the same manner described above. Pressurization of canister 304 is achieved by closing outlet valve 134 and opening inlet valve 124. The oxygen enriched air exits canister 304 through check valve 144.
In an exemplary implementation, a portion of the oxygen enriched air may be transferred from canister 302 to canister 304 when canister 304 is being vented of nitrogen. Transfer of oxygen enriched air from canister 302 to canister 304 during venting of canister 304 helps to desorb nitrogen from the adsorbent by lowering the partial pressure of nitrogen adjacent the adsorbent. The flow of oxygen enriched air also helps to purge desorbed nitrogen (and other gases) from the canister. Flow of oxygen enriched air between the canisters is controlled using flow restrictors and valves, as depicted in
Oxygen enriched air in accumulator 106 passes through supply valve 160 into expansion chamber 162 which is formed in housing component 510. An opening (not shown) in housing component 510 couples accumulator 106 to supply valve 160. In an implementation, expansion chamber 162 may include one or more devices configured to estimate an oxygen purity (fractional oxygen concentration, typically expressed as a percentage) of the gas passing through the chamber.
An outlet system, coupled to one or more of the canisters, includes one or more conduits for providing oxygen enriched air to a user. In an implementation, oxygen enriched air produced in either of canisters 302 and 304 is collected in accumulator 106 through check valves 142 and 144, respectively, as depicted schematically in
Turning to
Oxygen enriched air in accumulator 106 passes through supply valve 160 into expansion chamber 162 as depicted in
The fluid dynamics of the outlet pathway, coupled with the programmed actuations of supply valve 160, may result in a bolus of oxygen being provided at the correct time and with an amplitude profile that assures rapid delivery into the user's lungs without excessive waste.
Expansion chamber 162 may include one or more oxygen sensors adapted to determine an oxygen purity of gas passing through the chamber. In an implementation, the oxygen purity of gas passing through expansion chamber 162 is estimated using an oxygen sensor 165. An oxygen sensor is a device configured to measure oxygen purity of a gas. Examples of oxygen sensors include, but are not limited to, ultrasonic oxygen sensors, electrical oxygen sensors, chemical oxygen sensors, and optical oxygen sensors. In one implementation, oxygen sensor 165 is an ultrasonic oxygen sensor that includes an ultrasonic emitter 166 and an ultrasonic receiver 168. In some implementations, ultrasonic emitter 166 may include multiple ultrasonic emitters and ultrasonic receiver 168 may include multiple ultrasonic receivers. In implementations having multiple emitters/receivers, the multiple ultrasonic emitters and multiple ultrasonic receivers may be axially aligned (e.g., across the gas flow path which may be perpendicular to the axial alignment).
In use, an ultrasonic sound wave from emitter 166 may be directed through oxygen enriched air disposed in chamber 162 to receiver 168. The ultrasonic oxygen sensor 165 may be configured to detect the speed of sound through the oxygen enriched air to determine the composition of the oxygen enriched air. The speed of sound is different in nitrogen and oxygen, and in a mixture of the two gases, the speed of sound through the mixture may be an intermediate value proportional to the relative amounts of each gas in the mixture. In use, the sound at the receiver 168 is slightly out of phase with the sound sent from emitter 166. This phase shift is due to the relatively slow velocity of sound through a gas medium as compared with the relatively fast speed of the electronic pulse through wire. The phase shift, then, is proportional to the distance between the emitter and the receiver and inversely proportional to the speed of sound through the expansion chamber 162. The density of the gas in the chamber affects the speed of sound through the expansion chamber and the density is proportional to the ratio of oxygen to nitrogen in the expansion chamber. Therefore, the phase shift can be used to measure the concentration of oxygen in the expansion chamber. In this manner the relative concentration of oxygen in the accumulator may be estimated as a function of one or more properties of a detected sound wave traveling through the accumulator.
In some implementations, multiple emitters 166 and receivers 168 may be used. The readings from the emitters 166 and receivers 168 may be averaged to reduce errors that may be inherent in turbulent flow systems. In some implementations, the presence of other gases may also be detected by measuring the transit time and comparing the measured transit time to predetermined transit times for other gases and/or mixtures of gases.
The sensitivity of the ultrasonic oxygen sensor system may be increased by increasing the distance between the emitter 166 and receiver 168, for example to allow several sound wave cycles to occur between emitter 166 and the receiver 168. In some implementations, if at least two sound cycles are present, the influence of structural changes of the transducer may be reduced by measuring the phase shift relative to a fixed reference at two points in time. If the earlier phase shift is subtracted from the later phase shift, the shift caused by thermal expansion of expansion chamber 162 may be reduced or cancelled. The shift caused by a change of the distance between the emitter 166 and receiver 168 may be approximately the same at the measuring intervals, whereas a change owing to a change in oxygen purity may be cumulative. In some implementations, the shift measured at a later time may be multiplied by the number of intervening cycles and compared to the shift between two adjacent cycles. Further details regarding sensing of oxygen in the expansion chamber may be found, for example, in U.S. patent application Ser. No. 12/163,549, entitled “Oxygen Concentrator Apparatus and Method”, which published as U.S. Publication No. 2009/0065007 A1 on Mar. 12, 2009 and is incorporated herein by reference.
Flow rate sensor 185 may be used to determine the flow rate of gas flowing through the outlet system. Flow rate sensors that may be used include, but are not limited to: diaphragm/bellows flow meters; rotary flow meters (e.g. Hall effect flow meters); turbine flow meters; orifice flow meters; and ultrasonic flow meters. Flow rate sensor 185 may be coupled to controller 400. The rate of gas flowing through the outlet system may be an indication of the breathing volume of the user. Changes in the flow rate of gas flowing through the outlet system may also be used to determine a breathing rate of the user. Controller 400 may generate a control signal or trigger signal to control actuation of supply valve 160. Such control of actuation of the supply valve may be based based on the breathing rate and/or breathing volume of the user, as estimated by flow rate sensor 185.
In some implementations, ultrasonic oxygen sensor 165 and, for example, flow rate sensor 185 may provide a measurement of an actual amount of oxygen being provided. For example, flow rate sensor 185 may measure a volume of gas (based on flow rate) provided and ultrasonic oxygen sensor 165 may provide the concentration of oxygen of the gas provided. These two measurements together may be used by controller 400 to determine an approximation of the actual amount of oxygen provided to the user.
Oxygen enriched air passes through flow rate sensor 185 to filter 187. Filter 187 removes bacteria, dust, granule particles, etc. prior to providing the oxygen enriched air to the user. The filtered oxygen enriched air passes through filter 187 to connector 190. Connector 190 may be a “Y” connector coupling the outlet of filter 187 to pressure sensor 194 and delivery conduit 192. Pressure sensor 194 may be used to monitor the pressure of the gas passing through delivery conduit 192 to the user. In some implementations, pressure sensor 194 is configured to generate a signal that is proportional to the amount of positive or negative pressure applied to a sensing surface. Changes in pressure, sensed by pressure sensor 194, may be used to determine a breathing rate of a user, as well as to detect the onset of inhalation (also referred to as the trigger instant) as described below. Controller 400 may control actuation of supply valve 160 based on the breathing rate and/or onset of inhalation of the user. In an implementation, controller 400 may control actuation of supply valve 160 based on information provided by either or both of the flow rate sensor 185 and the pressure sensor 194.
Oxygen enriched air may be provided to a user through delivery conduit 192. In an implementation, delivery conduit 192 may be a silicone tube. Delivery conduit 192 may be coupled to a user using an airway delivery device 196, as depicted in
In an alternate implementation, a mouthpiece may be used to provide oxygen enriched air to the user. As shown in
Mouthpiece 198 is removably positionable in a user's mouth. In one implementation, mouthpiece 198 is removably couplable to one or more teeth in a user's mouth. During use, oxygen enriched air is directed into the user's mouth via the mouthpiece. Mouthpiece 198 may be a night guard mouthpiece which is molded to conform to the user's teeth. Alternatively, mouthpiece may be a mandibular repositioning device. In an implementation, at least a majority of the mouthpiece is positioned in a user's mouth during use.
During use, oxygen enriched air may be directed to mouthpiece 198 when a change in pressure is detected proximate to the mouthpiece. In one implementation, mouthpiece 198 may be coupled to a pressure sensor 194. When a user inhales air through the user's mouth, pressure sensor 194 may detect a drop in pressure proximate to the mouthpiece. Controller 400 of oxygen concentrator 100 may control release of a bolus of oxygen enriched air to the user at the onset of inhalation.
During typical breathing of an individual, inhalation may occur through the nose, through the mouth or through both the nose and the mouth. Furthermore, breathing may change from one passageway to another depending on a variety of factors. For example, during more active activities, a user may switch from breathing through their nose to breathing through their mouth, or breathing through their mouth and nose. A system that relies on a single mode of delivery (either nasal or oral), may not function properly if breathing through the monitored pathway is stopped. For example, if a nasal cannula is used to provide oxygen enriched air to the user, an inhalation sensor (e.g., a pressure sensor or flow rate sensor) is coupled to the nasal cannula to determine the onset of inhalation. If the user stops breathing through their nose, and switches to breathing through their mouth, the oxygen concentrator 100 may not know when to provide the oxygen enriched air since there is no feedback from the nasal cannula. Under such circumstances, oxygen concentrator 100 may increase the flow rate and/or increase the frequency of providing oxygen enriched air until the inhalation sensor detects an inhalation by the user. If the user switches between breathing modes often, the default mode of providing oxygen enriched air may cause the oxygen concentrator 100 to work harder, limiting the portable usage time of the system.
In an implementation, mouthpiece 198 is used in combination with nasal cannula airway delivery device 196 to provide oxygen enriched air to a user, as depicted in
Operation of oxygen concentrator 100 may be performed automatically using an internal controller 400 coupled to various components of the oxygen concentrator 100, as described herein. Controller 400 includes one or more processors 410 and internal memory 420, as depicted in
In some implementations, controller 400 includes processor 410 that includes, for example, one or more field programmable gate arrays (FPGAs), microcontrollers, etc. included on a circuit board disposed in oxygen concentrator 100. Processor 410 is configured to execute programming instructions stored in memory 420. In some implementations, programming instructions may be built into processor 410 such that a memory external to the processor 410 may not be separately accessed (i.e., the memory 420 may be internal to the processor 410).
Processor 410 may be coupled to various components of oxygen concentrator 100, including, but not limited to compression system 200, one or more of the valves used to control fluid flow through the system (e.g., valves 122, 124, 132, 134, 152, 154, 160), oxygen sensor 165, pressure sensor 194, flow rate sensor 185, temperature sensors (not shown), fan 172, and any other component that may be electrically controlled. In some implementations, a separate processor (and/or memory) may be coupled to one or more of the components.
Controller 400 is configured (e.g. programmed by program instructions) to operate oxygen concentrator 100 and is further configured to monitor the oxygen concentrator 100 such as for malfunction states or other process information. For example, in one implementation, controller 400 is programmed to trigger an alarm if the system is operating and no breathing is detected by the user for a predetermined amount of time. For example, if controller 400 does not detect a breath for a period of 75 seconds, an alarm LED may be lit and/or an audible alarm may be sounded. If the user has truly stopped breathing, for example, during a sleep apnea episode, the alarm may be sufficient to awaken the user, causing the user to resume breathing. The action of breathing may be sufficient for controller 400 to reset this alarm function. Alternatively, if the system is accidentally left on when delivery conduit 192 is removed from the user, the alarm may serve as a reminder for the user to turn oxygen concentrator 100 off.
Controller 400 is further coupled to oxygen sensor 165, and may be programmed for continuous or periodic monitoring of the oxygen purity of the oxygen enriched air passing through expansion chamber 162. A minimum oxygen purity threshold may be programmed into controller 400, such that the controller lights an LED visual alarm and/or an audible alarm to warn the user of the low concentration of oxygen.
Controller 400 is also coupled to internal power supply 180 and may be configured to monitor the level of charge of the internal power supply. A minimum voltage and/or current threshold may be programmed into controller 400, such that the controller lights an LED visual alarm and/or an audible alarm to warn the user of low power condition. The alarms may be activated intermittently and at an increasing frequency as the battery approaches zero usable charge.
The server 460 may also be in wireless communication with the portable computing device 480 using a wireless communication protocol such as GSM. A processor of the smartphone 480 may execute a program 482 known as an “app” to control the interaction of the smartphone 480 with the user 1000, the POC 100, and/or the server 460. The server 460 may have access to a database 466 that stores operational data about the POC 100 and user 1000.
The server 460 includes an analysis engine 462 that may execute methods of operating and monitoring the POC 100. The server 460 may also be in communication via the network 470 with other devices such as a personal computing device 464 via a wired or wireless connection. A processor of the personal computing device 464 may execute a “client” program to control the interaction of the personal computing device 464 with the server 460. One example of a client program is a browser.
Further functions that may be implemented with or by the controller 400 are described in detail in other sections of this disclosure.
Control panel 600 serves as an interface between a user and controller 400 to allow the user to initiate predetermined operation modes of the oxygen concentrator 100 and to monitor the status of the system.
In some implementations, control panel 600 may include buttons to activate various operation modes for the oxygen concentrator 100. For example, control panel may include power button 610, flow rate setting buttons 620 to 626, active mode button 630, sleep mode button 635, altitude button 640, and a battery check button 650. In some implementations, one or more of the buttons may have a respective LED that may illuminate when the respective button is pressed, and may power off when the respective button is pressed again. Power button 610 may power the system on or off. If the power button is activated to turn the system off, controller 400 may initiate a shutdown sequence to place the system in a shutdown state (e.g., a state in which both canisters are pressurized).
Flow rate setting buttons 620, 622, 624, and 626 allow a flow rate of oxygen enriched air to be selected (e.g., 0.2 LPM by button 620, 0.4 LPM by button 622, 0.6 LPM by button 624, and 0.8 LPM by button 626). In other implementations, the number of flow rate settings may be increased or decreased. After a flow rate setting is selected, oxygen concentrator 100 will then control operations to achieve production of the oxygen enriched air according to the selected flow rate setting. Optionally, the control panel may include one or more hybrid button(s) to activate any of the hybrid modes described herein. Optionally, the control panel may include a POD button to activate a POD mode. Thus, the device may be set to operate in a traditional bolus mode (POD) where the device merely releases bolus for patient inspiration such as in accordance with the set flow rate, a continuous flow mode (CFM) where the device provides gas flow with gas characteristics that generally remain constant for inspiration and expiration such as in accordance with the set flow rate, and/or a hybrid mode where the gas characteristics generally change for inspiration and expiration as discussed herein. In some cases, the controller may automatically change from a mode of higher power consumption to a mode of lower power consumption based on remaining battery life. For example, on detection of a low battery condition such as when the controller is configured with a voltage detection circuit (e.g., an undervoltage detector) to sample battery voltage, the controller may switch from a continuous mode to a hybrid mode or a POD mode. Similarly, on detection of a low or lower battery condition, the controller may switch from hybrid mode to a POD mode.
Altitude button 640 may be activated when a user is going to be in a location at a higher elevation than the oxygen concentrator 100 is regularly used by the user.
Battery check button 650 initiates a battery check routine in the oxygen concentrator 100 which results in a relative battery power remaining LED 655 being illuminated on control panel 600.
The user may manually indicate active mode or sleep mode by pressing button 630 for active mode or button 635 for sleep mode.
The methods of operating and monitoring the POC 100 described below may be executed by the one or more processors, such as the one or more processors 410 of the controller 400, configured by program instructions, such as including, as previously described, the one or more functions and/or associated data corresponding thereto, stored in a memory such as the memory 420 of the POC 100. Alternatively, some or all of the steps of the described methods may be similarly executed by one or more processors of an external computing device, such as the server 460, forming part of the connected POC therapy system 450, as described above. In this latter implementation, the processors 410 may be configured by program instructions stored in the memory 420 of the POC 100 to transmit to the external computing device the measurements and parameters necessary for the performance of those steps that are to be carried out at the external computing device.
The main use of an oxygen concentrator 100 is to provide supplemental oxygen to a user. One or more flow rate settings may be selected on a control panel 600 of the oxygen concentrator 100, which then will control operations to achieve production of the oxygen enriched air according to the selected flow rate setting. In some versions, a plurality of flow rate settings may be implemented (e.g., five flow rate settings). The controller 400 may implement a POD (pulsed oxygen delivery) or demand mode of operation. Controller 400 may regulate the volume of the one or more released pulses or boluses to achieve delivery of the oxygen enriched air according to the selected flow rate setting. The flow rate settings on the control panel 600 may correspond to minute volumes (bolus volume multiplied by breathing rate per minute) of delivered oxygen, e.g. 0.2 LPM, 0.4 LPM, 0.6 LPM, 0.8 LPM, 1.1 LPM.
Oxygen enriched air produced by oxygen concentrator 100 is stored in an oxygen accumulator 106 and, in a POD mode of operation, released to the user as the user inhales. The amount of oxygen enriched air provided by oxygen concentrator 100 is controlled, in part, by supply valve 160. In an implementation, supply valve 160 is opened for a sufficient amount of time to provide the appropriate amount of oxygen enriched air, as estimated by controller 400, to the user. In order to minimize the wastage of oxygen, controller 400 may be programmed to open the supply valve 160 to release a bolus of oxygen enriched air soon after the onset of a user's inhalation is detected. For example, the bolus of oxygen enriched air may be provided in the first few milliseconds of a user's inhalation. Releasing a bolus of oxygen enriched air to the user as the user inhales may prevent wastage of oxygen by not releasing oxygen, for example, when the user is exhaling.
In an implementation, a sensor such as a pressure sensor 194 may be used to detect the onset of inhalation by the user and thereby trigger the release of a bolus. For example, the onset of inhalation may be detected by using pressure sensor 194. In use, delivery conduit 192 for providing oxygen enriched air is coupled to the user's nose and/or mouth through the nasal airway delivery device 196 and/or mouthpiece 198. The pressure in delivery conduit 192 is therefore representative of the user's airway pressure and hence indicative of user respiration. At the onset of inhalation, the user begins to draw air into their body through the nose and/or mouth. As the air is drawn in, a negative pressure is generated at the end of delivery conduit 192, due, in part, to the venturi action of the air being drawn across the end of delivery conduit 192. Controller 400 analyses the pressure signal from the pressure sensor 194 to detect a drop in pressure indicating the onset of inhalation.
A positive change or rise in the pressure in delivery conduit 192 indicates an exhalation by the user. Controller 400 may analyze the pressure signal from pressure sensor 194 to detect a rise in pressure indicating the onset of exhalation. In one implementation, when a positive pressure change is sensed, supply valve 160 is closed until the next onset of inhalation is detected. Alternatively, supply valve 160 may be closed after a predetermined interval known as the bolus duration.
By measuring the intervals between adjacent onsets of inhalation, the user's breathing rate may be estimated. By measuring the intervals between onsets of inhalation and the subsequent onsets of exhalation, the user's inspiratory time may be estimated.
In other implementations, the pressure sensor 194 may be located in a sensing conduit that is in pneumatic communication with the user's airway, but separate from the delivery conduit 192. In such implementations the pressure signal from the pressure sensor 194 is therefore also representative of the user's airway pressure.
Hybrid mode therapy is a breath-synchronised therapy in which there is a non-zero inter-bolus flow of gas to the patient as well as boluses delivered in synchrony with inhalation as in POD mode. In such a mode, the controller may control operations of the device to activate delivery of the bolus at such synchrony times and otherwise control or operate the device to deliver the non-zero inter-bolus flow of gas. Thus, the device may provide a generally continuous flow of therapy gas during each respiratory cycle (i.e., inspiration and expiration) but the characteristic(s) of the gas flow (e.g., purity and/or flow rate) may differ during inspiration (or part of inspiration) relative to non-inspiration times or expiration. Examples of such modes are described in more detail herein. Such gas characteristic delivery differences for the hybrid mode(s) may be implemented with multiple flow paths within the oxygen concentrator that employ different configurations. For example, such gas characteristic delivery differences may be implemented with a primary flow path (or primary path) and one or more secondary flow paths (or secondary paths). In this regard, the primary path generally concerns the typical path for flow of therapy gas from the accumulator through the supply valve that releases inspiratory triggered boluses to the delivery conduit. The primary path may provide the therapy gas to the delivery conduit with a first gas characteristic. Moreover, a secondary path generally concerns a path for flow of therapy gas to the delivery conduit that is separate from the primary path. Such a secondary path may provide the therapy gas to the delivery conduit with a second gas characteristic that is different from the first gas characteristic. In some example implementations, therapy gas provision via the primary path may generally involve therapy gas provided for inspiration times, whereas therapy gas provision via the secondary path(s) may generally involve therapy gas provided for expiration times or non-inspiratory times. However, in other examples, the secondary path(s) may also provide therapy gas for inspiratory times. Examples of such different paths for different hybrid modes are discussed in more detail herein.
The lower oxygen purity of the inter-bolus flow means less oxygen is wasted than during conventional continuous flow, in which the oxygen purity and flow rate are generally constant. This in turn helps to extend battery life, since the device, including the compressor, does not need to work as hard as during conventional continuous flow to maintain system pressure at the desired value for the current flow rate setting. In addition, portable oxygen concentrators are limited in the volume of oxygen they can produce in a given time due to the design constraints (size, weight, power consumption, adsorbent mass). By conserving oxygen delivery, bilevel purity hybrid mode allows the other design constraints more room for optimisation.
The flow source 700 may be coupled to the downstream side of the flow restrictor 175 via a secondary flow path (SFP) comprising the secondary valve 710 and the flow restrictor 720. The secondary flow path is a different path from the primary flow path and may be operated to provide therapy gas with a different gas characteristic than the primary path. Thus, the flow in the secondary flow path is at a lower purity than the oxygen enriched air released by the supply valve 160 to the patient via the primary flow path (PFP). The controller 400 controls the secondary valve 710 to allow flow along the lower-purity path when a bolus is not being released by the supply valve 160. The controller 400 may also control the secondary valve 710 to prevent flow along the lower-purity path during bolus release. In other words, the secondary valve 710 may be actuated in anti-sync with the supply valve 160. As such, the controller 400 generates a control signal to control the secondary valve 710 to be open when the supply valve 160 is closed and closed when the supply valve 160 is open. In an alternative to the modified outlet system 350 for implementing bilevel purity hybrid mode, the two valves 160 and 710 may be replaced by a three-way valve (or a three-port valve) that is configured to couple the accumulator 106 to either the primary flow path (when triggered by the onset of inhalation) or the secondary, lower-purity path at all other times. The three-way valve may be either downstream of the flow restrictors 175 and 720 or upstream of a single flow restrictor which replaces and combines the effects of the flow restrictors 175 and 720.
In one implementation, the flow source 700 may be the compressor 210 with an outlet to the secondary path. In such an implementation, the flow restrictor 720 is chosen such that the flow rate in the lower-purity path is approximately equal to the bolus flow rate in the higher-purity primary flow path (or primary path). In some implementations, the flow restrictor 720 may be omitted altogether, depending on the pressure of the flow source 700 and the pneumatic impedance of the secondary flow path.
In an alternative implementation, the flow source 700 may be a secondary compressor with an outlet to the secondary path. Such a compressor may be configured to generate a flow of air at flow rates approximately equal to the bolus flow rates in the higher-purity path. In such an implementation the flow restrictor 720 may be omitted. The secondary compressor may optionally be controlled by the controller 400 to achieve the specified flow rates.
In either such implementation, the oxygen purity in the lower-purity path is approximately that of ambient air (21%).
In yet a further implementation of bilevel purity hybrid mode, the flow source 700 is a portion of the vented exhaust gas that has been re-routed from the outlet 130 (e.g., from the exhaust outlet of the canister(s)) to the lower-purity path. Such vented exhaust gas may be of oxygen purity typically around the ambient purity of 21%, but may be as high as 35% and as low as 4% depending on the amount of the purge flow. In one such implementation, the flow restrictor 720 is chosen such that the flow rate in the lower-purity path is approximately equal to the bolus flow rates in the higher-purity primary path. Thus, the therapy gas provided to the delivery conduit in such a hybrid mode may use both accumulated enriched gas (e.g., a bolus) and exhaust gas that may flow to the delivery conduit at least during patient inspiration and patient expiration. The hybrid mode may then vary a characteristic of the therapy gas, such as where the varied characteristic is oxygen purity. The varied oxygen purity may have a first oxygen purity during at least a portion of patient inspiration and a second oxygen purity after the portion of patient inspiration (e.g., during remaining inspiration and/or expiration). The first oxygen purity may be a purity in a range of about 50 percent to about 99 percent, which may be attributable to the bolus release gas and may be provided via the primary path to the delivery conduit. Moreover, the second oxygen purity may be a purity in a range of about 4 percent to 35 percent, which may be attributable to the vented exhaust gas and may be provided via the secondary path to the delivery conduit. Thus, the primary path, which generally concerns the path for flow of therapy gas from the accumulator via the supply valve that releases inspiratory triggered boluses to the delivery conduit, may provide the therapy gas with the first oxygen purity. Moreover, the secondary path, which is a flow path to the delivery conduit that is separate from the primary path, may provide the therapy gas with the second oxygen purity.
In some such implementations, the sensor configuration of the outlet system of
However, with the differential connection of
Optionally, the device may be controlled so that the bilevel purity hybrid mode can be deactivated. Thus, with the aforementioned secondary valve configuration(s), oxygen enriched air is not required to be produced in bilevel purity hybrid at all times using the modified outlet system 350. In some implementations, the controller 400 may maintain the secondary valve 710 in a closed state so that the oxygen enriched air can be delivered according to a different mode without use of the secondary path. For example, with the maintained closure state, the controller can operate the device to provide gas flow in a POD mode via the primary path. Optionally, the controller may be configured to operate in the POD mode until a control (e.g., a hybrid button or a comfort button) on the control panel 600 is activated. For example, the control may be activated if the user is experiencing dyspnea or shortness of breath and is in need of reassurance or comfort. Once such a control is activated, the controller 400 may generate control signals to operate the secondary valve such as to begin to open and close the secondary valve 710 in anti-sync with the supply valve 160 as described above to implement bilevel purity hybrid mode. Optionally, pressing of the button may trigger operation in the hybrid mode for a predetermined period or for an indefinite period until the control on the control panel is de-activated. For example, the comfort button may activate the hybrid mode for such a predetermined time period. The controller 400 then reverts to control of oxygen enriched air in a POD mode after the predetermined time. Pressing the hybrid button may activate the hybrid mode in a more continuous fashion such as until the user activates another mode or the device is turned off.
The lower flow rate of the inter-bolus flow means less oxygen is wasted than during conventional continuous flow, in which the flow rate and oxygen purity are generally constant over the breathing cycle. This in turn helps to extend battery life, since the device, including the compressor, does not need to work as hard as during conventional continuous flow to maintain system pressure at the desired value for the current flow rate setting. In addition, portable oxygen concentrators are limited in the volume of oxygen they can produce in a given time due to the design constraints (size, weight, power consumption, adsorbent mass). By conserving oxygen delivery, bilevel flow rate hybrid mode allows the other design constraints more room for optimisation.
The controller 400 is configured to control the secondary valve 810 to allow flow along the lower-flow path when the controller is not controlling a release of a bolus with the supply valve 160. The controller 400 may also control the secondary valve 810 to prevent flow along the lower-flow path during that controlled bolus release. In other words, the secondary valve 810 may be actuated in anti-sync with the supply valve 160. As such, the controller 400 generates a control signal to control the secondary valve 710 to be open when the supply valve 160 is closed and closed when the supply valve 160 is open.
The modified outlet system 500 may also implement the differentially connected pressure sensor 194 with the flow restrictor 730, as in the modified outlet system 350, to enable more accurate triggering.
Optionally, the device may be controlled so that the bilevel flow rate hybrid mode can be deactivated. Thus, with the aforementioned secondary valve configuration(s), oxygen enriched air is not required to be produced in bilevel flow rate hybrid mode at all times using the modified outlet system 500. In some implementations, the controller 400 may maintain the secondary valve 810 in a closed state so that the oxygen enriched air can be delivered according to a different mode without use of the secondary path. For example, with the maintained closure state, the controller can operate the device to provide gas flow in a POD mode via the primary flow path (or primary path). Similar to the operations previously described, the controller 400, such as in response to a user pressing a control button (e.g., a comfort button or a hybrid button), can operate in the bilevel flow rate hybrid mode by generating control signals to the aforementioned valves, either for a predetermined period of time or in a more continuous fashion as previously described.
In an alternative implementation, the modified outlet system 500 may be configured for providing the bilevel flow rate hybrid mode without the secondary valve 810. With the secondary valve 810 removed, the secondary, lower-flow path through the flow restrictor 820 provides a gas flow as long as the POC 100 itself is operating. To permit a lower flow rate of the secondary path relative to the primary path, the paths may be configured with different flow characteristics such that a flow characteristic of the primary path is different from a flow characteristic of the secondary path. For example, a flow restrictor of the secondary path may be chosen to restrict flow so as to achieve a lower flow rate of gas in the secondary path when compared to the flow rate of the primary path. Similarly, the pneumatic resistance of the primary and secondary flow paths may be chosen, such as according to different conduit sizes, to achieve the flow rate differences. For example, a smaller, more restrictive conduit may be chosen for the secondary path when compared to the conduit of the primary path.
In a further alternative modified outlet system for implementing bilevel flow rate hybrid mode, the valves 160 and 810 may be replaced by a three-way valve (e.g., three-port valve) that pneumatically couples the accumulator 106 to the primary path and the secondary flow path. Thus, the three-way valve may be activated by the controller to selectively pneumatically couple the accumulator to one of the primary path, such as when the controller is triggered by detection of the onset of inhalation, and the secondary, lower-flow path, such as at all other times.
One benefit of the bilevel flow rate hybrid delivery mode is that the oxygen enriched air delivered at a low flow rate via the secondary, lower-flow path “pools” within the delivery conduit 192 and is therefore available for inhalation as soon as inhalation begins, even before the opening of the primary path for the release of the bolus.
Such intermediate versions may be implemented with a controller 400 controlling a combination of components of the modified outlet systems 350 and 500 to implement both of the secondary lower-purity path (SPF from
Although the components of
The differentially connected pressure sensor 194 may be used with all examples of hybrid mode delivery in order to improve the accuracy of detection of inspiration and control of triggering of valve 160 for release of a bolus (and thereby the signals associated with the anti-sync operation of valves 710, 810.
For the purposes of the present technology disclosure, in certain forms of the present technology, one or more of the following definitions may apply. In other forms of the present technology, alternative definitions may apply.
Air: In certain forms of the present technology, air may be taken to mean atmospheric air, consisting of 78% nitrogen (N2), 21% oxygen (O2), and 1% water vapour, carbon dioxide (CO2), argon (Ar), and other trace gases.
Oxygen enriched air: Air with a concentration of oxygen greater than that of atmospheric air (21%), for example at least about 50% oxygen, at least about 60% oxygen, at least about 70% oxygen, at least about 80% oxygen, at least about 90% oxygen, at least about 95% oxygen, at least about 98% oxygen, or at least about 99% oxygen. “Oxygen enriched air” is sometimes shortened to “oxygen”.
Medical Oxygen: Medical oxygen is defined as oxygen enriched air with an oxygen purity of 80% or greater.
Ambient: In certain forms of the present technology, the term ambient will be taken to mean (i) external of the treatment system or patient, and (ii) immediately surrounding the treatment system or patient.
Flow rate: The volume (or mass) of air delivered per unit time. Flow rate may refer to an instantaneous quantity. In some cases, a reference to flow rate will be a reference to a scalar quantity, namely a quantity having magnitude only. In other cases, a reference to flow rate will be a reference to a vector quantity, namely a quantity having both magnitude and direction. Flow rate may be given the symbol Q. ‘Flow rate’ is sometimes shortened to simply ‘flow’ or ‘airflow’.
Flow therapy: Respiratory therapy comprising the delivery of a flow of air to an entrance to the airways at a controlled flow rate referred to as the treatment flow rate that is typically positive throughout the patient's breathing cycle.
Patient: A person, whether or not they are suffering from a respiratory disorder.
Pressure: Force per unit area. Pressure may be expressed in a range of units, including cmH2O, g-f/cm2 and hectopascal. 1 cmH2O is equal to 1 g-f/cm2 and is approximately 0.98 hectopascal (1 hectopascal=100 Pa=100 N/m2=1 millibar˜0.001 atm). In this specification, unless otherwise stated, pressure is given in units of cmH2O.
The term “coupled” as used herein means either a direct connection or an indirect connection (e.g., one or more intervening connections) between one or more objects or components. The phrase “connected” means a direct connection between objects or components such that the objects or components are connected directly to each other. As used herein the phrase “obtaining” a device means that the device is either purchased or constructed.
In the present disclosure, certain U.S. patents, U.S. patent applications, and other materials (e.g., articles) have been incorporated by reference. The text of such U.S. patents, U.S. patent applications, and other materials is, however, only incorporated by reference to the extent that no conflict exists between such text and the other statements and drawings set forth herein. In the event of such conflict, then any such conflicting text in such incorporated by reference U.S. patents, U.S. patent applications, and other materials is specifically not incorporated by reference in this patent.
Further modifications and alternative implementations of various aspects of the present technology may be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the technology. It is to be understood that the forms of the technology shown and described herein are to be taken as implementations. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the technology may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the technology. Changes may be made in the elements described herein without departing from the spirit and scope of the technology as described in the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020901121 | Apr 2020 | AU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/SG2021/050188 | 4/5/2021 | WO |
