Oxygen mask

Abstract

An oxygen mask includes a mask body defining a cavity configured to be positioned over a patient's mouth and nose, an oxygen port formed on an upper half portion of the mask body, an annular aperture formed on the mask body, and at least one vent formed on the mask body, wherein each vent is formed on the lower half portion of the mask body in such a manner that gas exhaled by a patient is directed to the vent.

Description

[0001] Cross-references to related applications

[0002] This application is a divisional application of Chinese Patent Application No. 201680080081.8. Technical Field

[0003] This disclosure relates to a mask that facilitates the delivery of oxygen to a patient. More specifically, the invention relates to an oxygen mask operable to define an oxygen reservoir that collects and stores an amount of oxygen available for the patient's breathing during medical procedures. Background Technology

[0004] This section provides background information relating to this disclosure, which is not necessarily prior art.

[0005] An oxygen mask is connected to an oxygen source that delivers oxygen directly to the patient's airway (i.e., nose and mouth). Conventional oxygen masks typically cover the entire nose and mouth area and have no openings to allow surgical instruments to enter the mouth or nose. While conventional masks can form a seal around the patient's airway and attempt to confine the area around the airway delivering oxygen, they have several drawbacks. In particular, most conventional oxygen masks tend to dilute the oxygen delivered to the patient. Furthermore, these masks cause oxygen to disperse around and away from the patient's airway, potentially leading to ineffective oxygen delivery.

[0006] Nasal cannula can be used as the primary and sole source of oxygenation. This approach has problems. For example, nasal cannulas typically deliver oxygen inefficiently and wastefully. Most conventional oxygen masks are designed and functioned under the assumption that the patient receiving the procedure inhales the delivered oxygen precisely. Furthermore, this method assumes that a sufficiently large amount of oxygen infused will actually eventually reach the patient. This logic is flawed. This practice is extremely wasteful due to the dilution and dispersion of oxygen delivered through a conventional mask. Attempting to deliver oxygen in this manner wastes a significant amount of oxygen that must be continuously delivered throughout the respiratory cycle. Only a very small fraction of the oxygen is actually delivered to the patient.

[0007] In an attempt to address the aforementioned issues, a specific type of oxygen mask / delivery system has been developed, which essentially deploys a “face veil.” After the patient is placed in a lateral or prone position, a plastic sheet or bag is used to cover the patient’s face following nasal intubation. The plastic sheet or bag is operable to define a veil over the airway, which retains an oxygen reservoir purportedly available for the patient’s use. These improved oxygen masks, commonly referred to as TSE masks, have been discussed in Shaul Cohen et al., “TSE 'Mask' Improves Oxygenation in Deeply Sedated Patients with Nasal Cannula during Upper Endoscopy.” Anesthesiology This was discussed in 107:A922, 2007. It was shown in a poster at the American College of Anesthesiologists Annual Meeting, October 2007, Chicago, Illinois.

[0008] The TSE mask is designed to enhance its effectiveness in suppressing oxygen saturation drop. First, the TSE mask's oxygen reservoir provides 40-60% of the inhaled oxygen fraction at a flow rate of 4 L / min. Therefore, intravenous sedatives administered after pre-oxygenation can achieve moderate to deep sedation while maintaining spontaneous breathing without oxygen saturation drop. Second, the patient's breathing is monitored using a carbon dioxide monitor placed above the trachea or a pediatric precordial stethoscope. Therefore, if the patient experiences apnea due to airway obstruction or excessive sedation, healthcare personnel still have an average of 2-3 minutes to manage the airway before oxygen saturation drop occurs.

[0009] Additionally, as Leigh JM states, “Variation in Performance of Oxygen TherapyDevices.” Annals of The Royal College of Surgeons of England As discussed in 1973;52(4):234-253, oxygen therapy has consistently lacked control over oxygen dosage. This lack of control over oxygen dosage is present in the use of conventional oxygen masks for oxygen therapy. As Leigh noted, the use of conventional oxygen masks “still rarely conforms to the most basic rules of rational treatment – ​​namely, administering a known dose of substance to produce a sustained optimal blood level.” The inability to consistently deliver a known dose of oxygen is at least in part due to the difficulty in assessing the patient-device relationship. Patient factors, such as maximum inspiratory flow rate (“PIFR”), can affect the amount of oxygen delivered to the patient. For example, PIFR can affect the mixture of oxygen in the oxygen mask, exhaled gas, and room air. Thus, patient-factor PIFR can result in the patient inhaling an unknown amount of oxygen with each breath.

[0010] Ventimask® is a conventional oxygen mask designed to improve the efficacy of controlling the dose of oxygen delivered to a patient. Ventimask attempts to achieve this improved control by reducing the dependence of the dose of oxygen on patient factors PIFR. To this end, Ventimask is a high flow device that delivers an oxygen mixture at a flow rate above PIFR, such as 30 L / min - 45 L / min. However, to reduce the dependence on PIFR, Ventimask is limited to high flow rates, particularly flow rates greater than or equal to PIFR.

[0011] Additionally, conventional masks are typically compromised in performance due to sealing issues. Medical personnel typically do not take extra care in sealing conventional oxygen masks to a patient's face, which results in leaks and allows room air entrainment. Room air entrainment exacerbates the problem of lack of control of the dose of oxygen in conventional oxygen masks, as the oxygen is further diluted by room air. Even in cases where a conventional oxygen mask is carefully applied to a patient's face, there is typically a leak due to the difference between the profile of the conventional oxygen mask and the shape of the patient's face. Thus, the leak resulting from an incomplete seal is a common factor leading to the lack of control of the dose of oxygen in conventional oxygen masks.

[0012] Furthermore, conventional masks are typically not suitable for use in upper endoscopy procedures that require surgical instruments to be deployed through the patient's mouth and throat. For example, conventional masks do not include sufficient holes to allow surgical tools to access the mouth or nose. In this regard, an oxygen mask is needed that effectively delivers oxygen while having openings or apertures through which surgical instruments can be deployed. The openings or apertures in the mask must have sufficient flexibility to enable instruments to be easily and quickly manipulated, as occurs when deploying instruments in upper endoscopy procedures.

[0013] In an attempt to introduce an oxygen mask suitable for allowing surgical tools to access the mouth and nose in upper endoscopy procedures, a particular type of oxygen mask / delivery system has been developed. These surgical masks, commonly referred to as panoramic oxygen masks ("POMs"), have been discussed in US 8,960,195 to Lehman. US 8,960,195 describes an intubation-friendly oxygen mask that can be worn during standard oxygen therapy. The mask is intended to provide increased oxygen saturation and continuous monitoring of exhaled carbon dioxide. The mask introduces holes in the mask above the mouth to allow surgical tools to access the mouth and nose during upper endoscopy procedures.

[0014] While some conventional masks are designed for upper endoscopy procedures, these conventional masks still present health risks. For example, conventional masks designed for upper endoscopy procedures provide suboptimal monitoring of the patient. In 80% or more of cases, when a patient is sedated, an anesthesiologist can not be in the operating room. In this case, in addition to the normal workload (e.g., paperwork, administering drugs, following orders from the endoscopist or other doctors, protecting agitated and / or thrashing patients), a nurse typically also monitors the patient's oxygenation status and respiratory status. Indications of respiration can include: level of consciousness (e.g., verbal response to commands can determine the patient's level of consciousness), visual signs of respiration, vital signs (e.g., blood pressure, heart rate), EKG, oxygen saturation (oximetry), and carbon dioxide levels. However, determining all of these indications can occur in dark conditions or settings with less light, which can reduce accurate monitoring of the patient's respiratory and oxygenation status.

[0015] Most conventional and commonly used oxygen supplementation methods for upper endoscopy are the use of nasal cannula, and capnography machines are typically used to monitor respiration. To measure the patient's oxygen status, a finger monitor is typically used. However, these monitoring techniques present problems. For example, the CO2monitoring machines use the same or similar alarms when a negative event is detected. Thus, the alarm sound of the CO2monitoring machine does not specify to the caregiver whether the patient is not breathing, the O2saturation is low, or any other number of reasons that triggered the alarm. Furthermore, the CO2monitoring machine does not indicate the cause of the trigger. For example, if the O2saturation is low, the caregiver must still determine whether it is because the patient is breathing through the mouth or for some other reason. Each reason that can trigger the alarm can have a different appropriate response. If the patient has too little oxygen in their body, the O2flow rate can be increased to provide more oxygen. If the patient's airway is obstructed, the airway must be opened. Without knowing the cause of the alarm, the caregiver must take time to determine the cause. In many cases, false alarms can be triggered by events such as patient thrashing, further making it more difficult for the caregiver to react appropriately and disrupting the work environment. The net effect of the CO2monitoring technology of conventional oxygen masks designed for upper endoscopy procedures compromises patient safety.

[0016] While there have been various attempts to improve other conventional masks, all conventional masks, including masks designed for upper endoscopy procedures, have one or more of the following safety and effectiveness related problems: air entrainment, rebreathing of mechanical dead space air, lack of an effective continuous oxygen delivery system, oxygen waste (or other target gas or drug), limitations in dose control, ineffective monitoring of exhaled gases for early identification of adverse events, compromise of false alarms, bulkiness, and high cost.

[0017] It has been recognized that there is a significant need for an oxygen mask that can more efficiently and effectively provide oxygen enriched gas for easier uptake by the patient's airway upon inhalation while the patient is wearing the oxygen mask.

[0018] There is also a need for an oxygen mask that can improve monitoring of a patient undergoing an upper endoscopy procedure for early detection and prevention of oxygen desaturation or other adverse events.

[0019] There is also a need for an oxygen mask that can provide a reservoir of oxygen enriched air immediately proximate to the patient's airway upon inhalation by the patient to a greater extent than conventional oxygen masks.

[0020] Furthermore, there is a need for a mask that can sustain a source of enriched oxygen as a reservoir immediately proximate to the patient's airway while consuming a significantly lesser amount of oxygen than prior art oxygen masks.

[0021] There is still a need for an oxygen mask that is simple in construction, easy to deploy, can be readily used as a combined synergistic device with a nasal cannula, and can be used by a patient undergoing an upper endoscopy procedure so that the instrumentation can be deployed relatively easily and flexibly through such a mask. SUMMARY

[0022] This section provides an overview of the disclosure and does not disclose in its entirety the full scope or all of its features.

[0023] In one embodiment, an oxygen mask is provided comprising: a mask body defining a cavity configured to be placed over a patient's mouth and nose, an oxygen port formed on an upper half of the mask body, an annular hole formed on the mask body, and at least one vent port formed on the mask body, wherein each vent port is formed on a lower half of the mask body in a manner to direct the patient's exhaled gas to the vent port.

[0024] In another embodiment, an oxygen mask is provided comprising: a mask body defining a cavity configured to be placed over a patient's mouth and nose, an oxygen port formed on an upper half of the mask body, an oxygen reservoir tube directly connected to a lower half of the mask body, an annular hole formed on the mask body, and a vent port formed on the oxygen reservoir tube, wherein the vent port is formed on the oxygen reservoir tube in a manner to direct the patient's exhaled gas to the vent port.

[0025] In yet another embodiment, there is provided an oxygen mask comprising: a mask body defining a cavity configured to be placed over a patient's nose without covering the patient's mouth, an oxygen port formed near or on the upper half of the mask body, an oxygen storage tube directly connected to the lower half of the mask body, a vent port formed on the oxygen storage tube, wherein the vent port is formed on the oxygen storage tube in a manner to direct the patient's exhaled gas to the vent port.

[0026] In yet another embodiment, there is provided an oxygen mask comprising: a mask body configured to be placed near a patient's nose without covering the patient's mouth, one or two prongs configured to connect to an oxygen source, an oxygen port, an oxygen storage tube directly connected to the lower half of the mask body, a vent port formed on the oxygen storage tube, wherein the vent port is formed on the oxygen storage tube in a manner to direct the patient's exhaled gas to the vent port.

[0027] Other applicable areas will become apparent from the description provided herein.

[0028] By way of non-limiting example, the present application provides the following embodiments: Embodiment 1. An oxygen mask comprising: a mask body defining a cavity configured to be placed over a patient's mouth and nose, an oxygen port formed on the upper half of the mask body, a ring-shaped hole formed on the mask body, and at least one vent port formed on the mask body, wherein each vent port is formed on the lower half of the mask body in a manner to direct the patient's exhaled gas to the vent port.

[0029] Embodiment 2. The oxygen mask of embodiment 1, further comprising a protrusion formed in the interior space of the mask body, the protrusion partially dividing the interior space of the mask body into a nasal portion and an oral portion.

[0030] Embodiment 3. The oxygen mask of embodiment 2, wherein the protrusion is configured to reduce the chance of air dilution of oxygen in the interior space by gas exhaled from the patient's mouth.

[0031] Embodiment 4. The oxygen mask of embodiment 3, wherein the mask comprises two vent ports.

[0032] Embodiment 5. The oxygen mask of embodiment 4, wherein the mask body comprises a first vent port on the left side of the mask body and a second vent port on the right side of the mask body.

[0033] Embodiment 6. The oxygen face mask of embodiment 5, further comprising: at least one nasal instrument port formed on an upper half of the face mask body, and a suction port formed between the nasal instrument port and the vent port.

[0034] Embodiment 7. The oxygen face mask of embodiment 6, further comprising: at least one slit formed on a lower half of the face mask body.

[0035] Embodiment 8. The oxygen face mask of embodiment 1, further comprising at least one recess formed on the face mask body, wherein each recess is configured to allow direct access of an external oxygen source to the patient's nostrils.

[0036] Embodiment 9. The oxygen face mask of embodiment 8, wherein the face mask has two recesses.

[0037] Embodiment 10. The oxygen face mask of embodiment 9, wherein the oxygen port is connected with a hose to allow oxygen to be directly delivered to the nose or to allow direct sampling of carbon dioxide from the nose.

[0038] Embodiment 11. The oxygen face mask of embodiment 10, wherein each vent port is formed within 3 inches from a bottom most point of the face mask body.

[0039] Embodiment 12. The oxygen face mask of embodiment 11, wherein each vent port is formed within 2 inches from a bottom most point of the face mask body.

[0040] Embodiment 13. The oxygen face mask of embodiment 12, wherein the interior space of the face mask body is configured to store about 25 to about 100 cubic centimeters of oxygen when the oxygen face mask is worn.

[0041] Embodiment 14. The oxygen face mask of embodiment 13, wherein the oxygen face mask is configured to deliver about 95% to about 100% of oxygen to the patient during an inhalation phase of the patient's breathing.

[0042] Embodiment 15. The oxygen face mask of embodiment 6, further comprising an interface that inhibits the interior space of the face mask body from being heavily contaminated with room air when the oxygen face mask is used on a patient, wherein the interface is selected from the group consisting of: a gasket, a filler, a foam body, and an elastomer.

[0043] Embodiment 16. The oxygen face mask of embodiment 15, wherein each vent port is configured to have a filter housed therein.

[0044] Embodiment 17. The oxygen mask of embodiment 16, wherein the hose is configured to deliver medication and gas to the interior space.

[0045] Embodiment 18. An oxygen mask comprising: a mask body defining a cavity configured to be positioned over a patient's mouth and nose, an oxygen port formed on an upper half of the mask body, an oxygen reservoir tube directly connected to a lower half of the mask body, an annular hole formed on the mask body, and a vent formed on the oxygen reservoir tube, wherein the vent is formed on the oxygen reservoir tube in a manner that directs gas exhaled by the patient to the vent.

[0046] Embodiment 19. The oxygen mask of embodiment 18, wherein the oxygen reservoir tube is adjustable to increase or decrease a storage volume of the oxygen reservoir tube.

[0047] Embodiment 20. The oxygen mask of embodiment 19, wherein the oxygen mask is configured to store greater than about 20 cubic centimeters of oxygen when the oxygen mask is worn.

[0048] Embodiment 21. The oxygen mask of embodiment 20, wherein the oxygen reservoir tube is connected to a filter or a continuous positive airway pressure machine.

[0049] Embodiment 22. An oxygen mask comprising: a mask body defining a cavity configured to be positioned over a patient's nose without covering the patient's mouth, an oxygen port formed on or near a middle portion or an upper half of the mask body, an oxygen reservoir tube directly connected to a lower half of the mask body, a vent formed on the oxygen reservoir tube, wherein the vent is formed on the oxygen reservoir tube in a manner that directs gas exhaled by the patient to the vent.

[0050] Embodiment 23. The oxygen mask of embodiment 22, wherein the oxygen reservoir tube is adjustable to increase or decrease a storage volume of the oxygen reservoir tube.

[0051] Embodiment 24. The oxygen mask of embodiment 23, wherein the oxygen mask is configured to store greater than or equal to about 15 cubic centimeters of oxygen when the oxygen mask is worn.

[0052] Embodiment 25. The oxygen mask of embodiment 24, wherein the oxygen mask is configured to store greater than about 100 cubic centimeters of oxygen when the oxygen mask is worn.

[0053] Embodiment 26. An oxygen mask comprising: a mask body configured to be positioned near the nose of a patient without covering the mouth of the patient, one or two nasal pillow prongs configured to connect to an oxygen source, an oxygen port, an oxygen reservoir tube directly connected to a lower half of the mask body, a vent formed on the oxygen reservoir tube, wherein the vent is formed on the oxygen reservoir tube in a manner that directs gas exhaled by the patient to the vent.

[0054] Embodiment 27. The oxygen mask of embodiment 26, wherein the oxygen reservoir tube is adjustable to increase or decrease the storage volume of the oxygen reservoir tube.

[0055] Embodiment 28. The oxygen mask of embodiment 26, wherein the nasal pillow prongs are configured to fit into the nostrils of a patient.

[0056] Embodiment 29. The oxygen mask of embodiment 26, comprising two reservoir tubes, wherein one of the tubes is positioned on the left hand side and the other tube is positioned on the right hand side. BRIEF DESCRIPTION OF DRAWINGS

[0057] Figure 1 A conventional simple mask is shown.

[0058] Figure 2 An embodiment of a low FiO2 mask according to the present disclosure is shown.

[0059] Figure 3 A comparison of a conventional mask (such as Figure 1 ) and Figure 2 an embodiment thereof is shown.

[0060] Figure 4 A mask of Figure 2 further comprising a filter is shown.

[0061] Figure 5 An embodiment of a high FiO2 mask according to the present disclosure is shown.

[0062] Figure 6 A nasal oxygen conserving mask according to the present disclosure is shown.

[0063] Figure 7 An embodiment of an endoscopy mask according to the present disclosure is shown.

[0064] Figure 8 An endoscopy mask according to the present disclosure is shown. Figure 7 DETAILED DESCRIPTION

[0065] A multi-functional oxygen mask is provided for improving and controlling alveolar oxygen concentration. This can be achieved by strategically supplying oxygen according to a breathing cycle, which consists of three phases: expiration, expiratory pause (i.e. pause after expiration) and inspiration.

[0066] Conventional oxygen masks result in dilution of the intended oxygen (or other gas or drug) with a large amount of room air during each inspiration (especially early in inspiration). In some cases, the intended therapy (e.g. oxygen, other gases and drugs) can be effectively reduced by half or more. If a nasal cannula is used, this dilution occurs around the nasal area and if an open or ventilated system mask such as a simple mask or non-rebreathing mask is used as a supplemental oxygen delivery device, this dilution occurs around the vent located near the nasal area. Thus, the patient does not receive the required or appropriate amount of oxygen or drug.

[0067] The oxygen mask of the present disclosure can provide at least the following benefits: 1. Increased rescue capability in sedated medical procedures: By increasing the oxygen reserves in the patient during a sedated upper endoscopy procedure, the oxygen mask of the present disclosure can extend the safe period of respiratory pause of airway obstruction. Thus, the caregiver will have additional time to resolve the airway issue. This additional time can be life-saving.

[0068] Additionally, the oxygen mask of the present disclosure provides a more specific and sensitive CO2 monitor compared to a ventilated open mask or nasal cannula, which can result in fewer false alarms. The higher the accuracy of detecting respiratory problems, the better and earlier the problems can be detected. It is well known that capnography (waveform) is very important and must be deployed when a patient is under sedation for an upper endoscopy procedure. Capnography determines if a patient is breathing, if there is no CO2 waveform, it means there is no CO2 when breathing (expiration). This usually means there is an airway obstruction or the patient is not breathing or can be overly sedated or not beating a heart (i.e. cardiac arrest). It also indicates a slowing of breathing due to excessive sedation. It is the earliest detectable sign of a major adverse event and is an earlier signal than a pulse oximeter.

[0069] ​The oxygen mask of the present disclosure can reduce dilution or dispersion of CO2 compared to conventional masks (e.g., open airway masks) or nasal cannulas alone. There is no (or substantially no) CO2 build-up with each breath using the oxygen mask of the present disclosure because CO2 is pushed out of the oxygen mask by the continuous flow of oxygen during expiratory pause. Thus, there is no (or substantially no) CO2 present during inhalation, and exhaled CO2 during exhalation will be less diluted and less dispersed because the oxygen mask of the present disclosure requires lower continuous oxygen flow. Because CO2 is less diluted and dispersed, CO2 monitoring is more specific to respiratory issues. For example, the oxygen mask of the present disclosure can help tailor and make CO2 monitoring to the specific needs of each patient with each breath.

[0070] By providing a mechanism that can help prevent or correct airway obstruction to be identified more quickly and clearly, the oxygen mask of the present disclosure can enable caregivers to take appropriate action more quickly. For example, if a patient becomes apneic due to airway obstruction or over-sedation, the care team can still have several minutes to several minutes to act on the airway before a drop in oxygen saturation occurs. This is due to the high efficiency of alveolar oxygenation and early detection of airway obstruction by the oxygen mask of the present disclosure, which extends the safe period of apneic time.

[0071] 2. Reduce the number of medical condition misdiagnoses: Conventional oxygen masks can lead to medical condition misdiagnosis or false alarms due to various issues (e.g., baseline elevation due to rebreathing, less CO2 due to dilution). These flawed masks can lead to false alarms that disrupt workflow and have a tendency to overlook the most important monitoring. For example, an ineffective and inefficient oxygen and / or drug delivery system (e.g., due to room air dilution) can lead to misleading values of the amount of oxygen received by the patient. In doing so, there can be an impact of worse than actual cardiopulmonary shunt, increasing the need for unnecessary invasive and expensive diagnostic procedures and therapies. However, by reducing or eliminating dilution of oxygen (or other intended therapies), the oxygen mask of the present disclosure can reduce the false estimation of the amount of oxygen delivered to the patient. This in turn can reduce medical condition misdiagnosis, preventing sometimes risky and expensive unnecessary medical procedures, such as, for example, invasive medical interventions or endotracheal intubation requiring intensive care unit services.

[0072] 3. Reduce or eliminate rebreathing of exhaled gases: During exhalation, the fresh continuous flow of oxygen pushes the exhaled gases (e.g., dead space gases, carbon dioxide) and any indoor air that can have entered the oxygen mask. These gases are pushed into the atmosphere through the vent formed on the lower half of the oxygen mask. After each exhalation, the expiratory pause lasts for approximately 1 / 3 of the respiratory cycle, during which there is no air flow for breathing (expiration). The fresh continuous flow of oxygen continues to push the exhaled gases from the upper half of the oxygen mask to the lower half. The exhaled gases and any indoor air that enters the oxygen mask are pushed out of the reservoir into the atmosphere until all or almost all of the exhaled gases are pushed out into the atmosphere. This functionality of the oxygen mask of the present disclosure can eliminate the variability associated with the patient’s exhalation time, which can affect the gas composition (e.g., CO2) of the reservoir for the next inhalation.

[0073] As the exhaled gases and any indoor air inside the oxygen mask are pushed out, the fresh continuous flow of oxygen fills the reservoir-like space inside the oxygen mask between the nasal area and the vent. In this way, close to 100% oxygen is collected and stored near the nose to be drawn upon immediately during the next inhalation. Thus, upon inhalation, the patient inhales 100% or close to 100% oxygen. As a result, hypercarbia is suppressed since no or little carbon dioxide is inhaled.

[0074] 4. Reduction or elimination of dilution of oxygen with indoor air: With conventional oxygen delivery devices, there is a sudden tidal volume replacement during each inhalation. This is especially true during the early part of inhalation when the peak inspiratory flow rate (“PIFR”) occurs. With conventional oxygen delivery devices, a large amount of indoor air flows into the nose and dilutes the supplied oxygen at the time of PIFR. If a nasal cannula is used, this dilution occurs around the nasal area. If a vented oxygen mask is used, the two (or sometimes one) vents on each side of the mask near the nasal area cause dilution during the active early phase of inhalation. Because of this early inhalation phenomenon, open or vented oxygen delivery system devices such as simple masks, non-rebreathing oxygen mask (i.e., masks with the one-way valve removed) have a significant air dilution effect on alveolar oxygenation. In addition, Venturi masks and high flow nasal cannulas (“HFNC”) require high gas flows to avoid the indoor air dilution effect caused by the PIFR effect. Thus, these devices can require gas flows of 35 to 45 L / min to overcome the indoor air entrainment, which is an average of 3 to 4 times the minute ventilation of normal spontaneous breathing.

[0075] To avoid room air dilution, the oxygen mask of the present disclosure places each vent in either the upper or lower half opposite the nasal region to create a gas reservoir between the nasal region and the vent. During each early phase of inspiration, 100% oxygen stored during the expiratory pause (rather than diluted room air from the vent) is first breathed into the lungs, thereby avoiding (or delaying) the PIFR effect of room air. As such, the oxygen mask of the present disclosure can deliver a known 100% (or near 100%) storage of oxygen in the reservoir without room air dilution prior to entering the lungs.

[0076] The basic physiological function of PIFR is to enhance the speed of air movement to the alveoli to maximize effective and efficient oxygenation, especially during the very early phase of inspiration during normal spontaneous breathing. Thus, any air dilution during the early phase of inspiration using conventional oxygen devices can result in a lower percentage of inhaled O2, which defeats the purpose of PIFR seen during spontaneous breathing. The oxygen mask of the present disclosure can maximize the PIFR effect of any target gas or drug that needs to be delivered from the reservoir of the oxygen mask of the present disclosure to the lungs by delivering a known amount or dose of oxygen (or drug or other gas) to the patient on a controlled oxygen therapy.

[0077] 5. Reduction of oxygen waste: Conventional oxygen masks do not fully appreciate that the first half of inspiration (completely or mostly) is responsible for alveolar oxygenation. It has been clinically observed that oxygen is essentially only taken up into the blood during the early phase of inspiration during the breathing process. That is, during the early phase of inspiration, oxygen effectively reaches the alveoli. Oxygen applied during the later phase of inspiration remains in the “dead space” (such as the pharynx, trachea, and bronchi). Thus, approximately the first 1 / 6 of the breathing cycle is critical for alveolar oxygenation (the early portion of the first half of inspiration). It has thus been observed and concluded that it is more advantageous to apply a greater amount of oxygen. Also, it is useful (and effective) to apply oxygen only during the effective early phase of inspiration.

[0078] The effective early phase or maximum inspiratory flow rate time can last less than a second. For example, the effective early phase can last approximately 0.2 to 0.3 seconds. In another example, the effective early phase can last approximately 0.25 seconds. In most cases, the effective early phase is less than approximately one quarter of the duration of inspiration, and is typically approximately one eighth of the duration of inspiration. Thus, if oxygen is supplied at twice the normal volume per second (e.g., 100 cc / s rather than 50 cc / s), more than half of the savings will be realized. In some cases, more than three quarters of the savings can be realized.

[0079] Conventional oxygen masks cannot operate according to this effective early phase inhalation phenomenon. Thus, conventional oxygen masks do not deliver 100% or near 100% oxygen during the early phase of the first half of inhalation. Without any means of storing oxygen during expiratory pause, conventional oxygen masks waste continuous flow oxygen during these phases (by delivering oxygen to the atmosphere). Additionally, even during the first half of inhalation, much of the oxygen can be diluted by atmospheric air, resulting in oxygen being wasted and / or being at a low concentration affected by the maximum inhalation flow rate, even during the most effective phase. In some cases, less than 10% of the continuous flow of oxygen is delivered to the alveoli during each breath.

[0080] The oxygen mask of the present disclosure can reduce oxygen waste in at least two ways. First, by removing all or nearly all non-oxygen (e.g., C02and nitrogen) from the oxygen mask between expiration and the end of expiratory pause, there can be no or insignificant air entrainment. Thus, 100% (or near 100%) oxygen can be delivered to the alveoli during the early phase of the first half of inhalation. Second, the oxygen mask of the present disclosure provides a reservoir in the oxygen mask to collect and / or store oxygen during expiratory pause. In this way, continuous flow of oxygen can be maintained even when the patient is not inhaling. Thus, waste of fresh oxygen is reduced.

[0081] 6. Reducing or eliminating the effect of an improper mask seal on room air entrainment: The oxygen mask of the present disclosure can reduce or eliminate the effect of room air entrainment caused by an improper mask seal. While room air entrainment can occur through the vent of a conventional mask, room air entrainment can also occur due to an improper mask seal (e.g., a gap between the mask and the patient’s face). In some cases, the effect of room air entrainment due to an improper mask seal is often masked by the effect of room air entrainment through the vent, so medical personnel can be negligent of a proper mask seal. In the event that medical personnel are negligent, the oxygen mask of the present disclosure can not be secured and sealed to the patient’s face completely, resulting in a leak. While conventional oxygen masks tend to lack control over the oxygen dose due to room air entrainment caused by such leaks, the oxygen mask of the present disclosure can reduce or eliminate the effect of room air entrainment caused by an improper mask seal. By pushing any exhaled gases and room air out of the mask during expiration, and storing 100% oxygen near the nasal area during expiration and expiratory pause, the patient receives 100% near 100% oxygen at least during the first half of inhalation. Thus, the oxygen mask of the present disclosure reduces or eliminates the effect of room air entrainment caused by an improper mask seal on controlling the oxygen dose.

[0082] 7. Improving dose control: The following properties can allow the oxygen mask of the present disclosure to improve dose control: 1) No (or substantially no) air entrainment (not diluted by room air) during early inspiration; eliminating or reducing variability in room air entrainment of the patient and device self-PIFR effect during early inspiration; 2) No CO2 rebreathing; eliminating or reducing variability in the patient and device over the expiratory time; 3) A known amount of 100% oxygen is saved in the reservoir during each pause; 4) A known amount of 100% (or substantially 100%) oxygen is first delivered to the alveoli during the first half of inspiration via a continuous gas delivery (“SGD”) system, followed by a known amount of 100% (or substantially 100%) continuous flow oxygen with a known amount of room air having 21% oxygen; and 5) The ability to control the amount (dose) of oxygen by adjusting the reservoir volume and oxygen flow rate of the mask.

[0083] Conventional oxygen delivery devices rely on the accuracy of the promised FiO2 at the device level, not the alveolar level. The oxygen mask of the present disclosure can deliver, control, titrate, and maintain the desired proper amount (dose) of oxygen at the alveolar level.

[0084] The volume of the reservoir can vary depending on the desired O2 concentration. In some cases, the target FiO2 can be about 24% to about 60%. In other cases, the target FiO2 can be about 50% to about 100%. According to another embodiment, the reservoir varies from about 25 cc to 150 cc, and the oxygen mask can store up to about 400 cc total through the reservoir and attached oxygen storage tubing. The storage reservoir volume and oxygen flow rate of the oxygen mask of the present disclosure can be adjusted to accommodate the needs of each patient.

[0085] For example, the necessary storage reservoir volume and flow rate can be calculated using the patient tidal volume (“TV”), respiratory rate (“RR”), and target FiO2. If the patient’s TV is 450 cc, the respiratory rate is 20 / min, and the target FiO2 is 100%, the storage reservoir volume and oxygen flow rate can be calculated as follows: Since 2 / 3 of the patient's TV is delivered to the alveoli in the first half of inspiration, 300 cc (2 / 3 x 450 cc = 300 cc) is delivered to the alveoli. Using the oxygen mask of the present disclosure, the 300 cc delivered to the alveoli in the first half of inspiration can be 100% (or substantially 100%) Fi02. Thus, if "X" represents the amount of 100% oxygen stored in the reservoir during the expiratory pause, which constitutes 1 / 3 of the respiratory cycle, then ½ X represents the amount of oxygen delivered from the continuous flow oxygen source during the upper half of inspiration (since the first half of inspiration is ½ of the expiratory time duration). If "RA" represents the amount of 100% oxygen in room air (i.e., 21% oxygen) during the first half of inspiration, then the sum of X, ½ X, and RA is the final volume (300 cc) delivered to the alveoli in the first half of inspiration. This is shown in equation form: X + ½ X + RA = 300 cc of 100% oxygen. Solving for X shows that the total reservoir volume of the oxygen mask of the present invention should be given to the final volume of 300 cc delivered to the alveoli in the first half of inspiration: 1 X + ½ X + RA = 300 cc of 100% oxygen X + ½ X = 300 cc - RA X + ½ X = 300 cc - RA (3 / 2) X = 300 cc - RA X = (2 / 3) (300 cc - RA) X = 200 cc - (2 / 3) RA Since there is no room air during the first 300 cc of tidal alveolar ventilation, RA = 0, thus: X = 200 cc Therefore, for a final volume of 300 cc delivered to the alveoli during the first half of inspiration, the total storage volume is approximately 200 cc. Since the total storage volume is approximately 200 cc, if the oxygen mask of the present disclosure itself can store 150 cc, then any connected storage structure (such as a connected storage reservoir tube) can be adjusted to provide an additional 50 cc storage volume for a total storage volume of 200 cc. With the total storage volume, the appropriate flow rate can be calculated. Since the flow rate per breath phase is 200 cc / phase, and there are three breath phases (i.e., inspiration, expiration, expiratory pause), the flow rate per breath cycle is 600 cc / breath cycle (200 cc / phase x 3 phases / cycle = 600 cc / cycle). With a respiratory rate (“RR”) of 20 breath cycles per minute, the flow rate is 12 L / min (600 cc / cycle x 20 cycles / min = 12,000 cc / min). Therefore, if the oxygen mask of the present disclosure is adjusted to have a total storage volume of 200 cc and the flow rate is adjusted to 12 L / min, 100% oxygen stored in the reservoir (and any connected storage reservoir tube) of 200 cc, along with 100% oxygen from the continuous flow of the oxygen source, 100 cc, prior to the mixture of air and flowing oxygen within the delivery chamber, will result in a total of 300 cc of 100% oxygen delivered to the alveoli during the first half of inspiration, which includes the remaining amount of tidal volume (150 cc), for a total tidal flow volume of 450 cc. Since this embodiment utilizes a flow rate of 12 L / min, a higher FiO2 mask (such as the one shown in the embodiment) can be used. The above equations and calculations can be used to determine the appropriate total storage volume and flow rate. Figure 5

[0086] 8. Employing a continuous gas delivery (“SGD”) mode to improve alveolar oxygenation efficacy: During inspiration, in addition to the continuous flow of oxygen provided to the mask, the oxygen stored or collected in the storage space during the expiratory pause will also be delivered to the alveoli in an SGD mode. In this way, 100% oxygen is delivered first in the most efficient and effective oxygen delivery time (PIFR time) without chamber air dilution or exhaled gas from dead space ventilation. In many cases, this time frame is the first about 0.2 seconds to about 0.3 seconds of the early phase of inspiration. This initial oxygen delivery is followed by a supplemental tidal volume, which can include oxygen from the continuous oxygen flow and chamber air.

[0087] ​Accordingly, the oxygen mask of the present disclosure defines a reservoir for storing oxygen. According to one embodiment, the reservoir varies from about 20 cc to 200 cc. In one embodiment, the reservoir is about 20 cc to 100 cc or 75 cc to 150 cc. In a specific embodiment, the reservoir is about 75 cc. The volume can vary according to the design of the structure and the function of the mask for various different clinical applications. The oxygen stored during the expiratory pause is delivered as a bolus (about 20-150 cc in a 450 cc tidal volume) during inspiration. This early 20-150 cc bolus of oxygen enriched air will be effectively and efficiently taken into the alveoli at the time when oxygen exchange in the alveoli is most effective and efficient.

[0088] In use, the oxygen mask of the present disclosure can be used in combination with a nasal cannula, whereby the nasal cannula can be used as a source of oxygen flow with or without end tidal CO2 sampling, and the oxygen mask of the present disclosure can be used as a reservoir. Unlike conventional oxygen masks, the oxygen mask of the present disclosure is operable to define a reservoir that can be immediately collected, held, and made into an oxygen enriched reservoir. The reservoir can be directly adjacent to the patient's airway. When the patient breathes, the oxygen in the reservoir can be immediately inhaled. In this regard, during the pause between breaths by the patient, the oxygen continuously supplied through the nasal cannula will fill the reservoir defined by the mask.

[0089] Accordingly, the oxygen reservoir not only defines an oxygen reservoir, but it also selectively places oxygen directly around the patient's airway so that the patient can and must breathe in oxygen enriched air that is enriched relative to the air that is diluted and / or dissipated from the patient's nose and mouth when the patient inhales air. In this regard, the oxygen mask of the present disclosure can maintain the same bolus in close proximity to what the patient takes in with each breath.

[0090] The oxygen mask of the present disclosure can also deliver automatically adjusted back-up oxygen to accommodate air leaks or shallow breaths by patients with "night time oxygen saturation dips," which is a common and important problem in COPD patients in long term oxygen therapy.

[0091] This is in contrast to conventional oxygen masks that deploy a constant flow of oxygen and air, only a portion of which is actually consumed at a selected moment in time (e.g., the first 2 / 3 of the first half of inhalation) when the patient breathes. For example, using a standard nasal cannula and a conventional oxygen mask, the continuous flow of oxygen during patient exhalation is wasted to the atmosphere. The reservoir defined by the oxygen mask of the present disclosure, however, is designed to store approximately 20 cc and up to 150 cc of oxygen. The storage volume depends on a variety of factors, including but not limited to the patient’s respiratory rate and alveolar ventilation. This feature helps to reduce the effect of dilution / dispersion of the gas by room air at normal respiratory rates. By increasing efficiency and the subsequent benefit of more thorough oxygenation of the patient, a significantly higher degree of care can be provided.

[0092] Conventional masks that include a reservoir do not achieve the above objectives. For example, a conventional mask having three one-way valves and an attached storage bag does not achieve the above objectives at least because this type of mask does not effectively remove exhaled gas from within the mask body prior to the next inhalation. Thus, at inhalation, this conventional mask cannot first deliver 100% oxygen using the SGD mode because exhaled dead space air (rather than 100% oxygen) will be inhaled first. This conventional mask and its accessories create a mechanical dead space that limits its use in certain clinical applications as a rebreathing system. Because the dead space affects alveolar oxygenation (with exhaled gas) when the tidal volume or fresh gas flow is below normal levels, the use of this conventional mask for small patients (which have lower tidal volumes) is limited. Additionally, the maximum FiO2 of this conventional mask is limited below the FiO2 levels that can be achieved by the oxygen mask of the present disclosure, regardless of whether a higher oxygen flow rate is used.

[0093] 9. Improved control of the dose of oxygen (or other gas or medication) delivered to the patient: By adjusting the volume of oxygen stored in the reservoir during the exhalation phase, the oxygen mask of the present disclosure can more accurately determine the oxygen delivered to the alveoli. In doing so, the oxygen mask of the present disclosure can deliver a constant performance that is independent of patient factors PIFR and total exhalation time. The oxygen mask of the present disclosure acts as a reservoir during the exhalation pause and the oxygen delivered is not diluted by atmospheric air before entering the respiratory tract. By storing a known amount of oxygen in the oxygen mask of the present disclosure prior to inhalation, and by delivering the stored oxygen without dilution by atmospheric air before delivery to the lungs, the oxygen mask of the present disclosure is able to deliver a known amount of oxygen to the alveoli. Importantly, this allows the oxygen mask of the present disclosure to be independent of high flow rates to overcome the effect of PIFR-induced entrainment of room air during inhalation, for example, as shown by conventional oxygen masks such as the Ventimask.

[0094] Control of the oxygen dose is critical for several reasons. First, accurate delivery of a controlled dose of oxygen is beneficial for patients suffering from certain conditions. For certain conditions, lack of control over the oxygen dose can be detrimental or even fatal by delivering insufficient or excessive oxygen or delivering oxygen in inconsistent doses. For example, patients suffering from chronic obstructive pulmonary disease ("COPD") often require oxygen therapy because they often suffer from insufficient oxygen flow into the alveoli. In another example, many emergency patients require 100% oxygen delivery to stabilize the patient. Because COPD patients and many emergency patients often require a certain dose of oxygen to stabilize, insufficient oxygen delivery due to lack of oxygen control can further exacerbate the medical condition of the COPD patient or emergency patient. Thus, the oxygen mask of the present disclosure can more effectively stabilize these patients by accurately and consistently delivering the necessary dose of oxygen.

[0095] Other benefits of improved dose control include: more definitive and predictable alveolar oxygen concentration; standardized device performance; consistent device performance; safer and more effective use of the device; reduced confusion for the end user; device more capable of repeated assessment of treatment response; and improved diagnostic and prognostic value.

[0096] 10. Increased safety by delivering 100% (or near 100%) Fi02with lower oxygen flow: Delivery of 100% (or near 100%) Fi02is important for many patients (such as stroke patients, cardiac arrest patients, and patients with diseases characterized by hypoxic conditions) in emergency field or event until medical team care (e.g., ambulance pre-hospital care from the field to the hospital). Many emergency care vehicles (such as ambulances) carry conventional oxygen devices (such as non-rebreathing oxygen mask) that can deliver approximately 60% Fi02, far below 100%. Conventional non-rebreathing oxygen mask is the most widely recognized and used oxygen mask in the healthcare field and is designed to deliver the maximum oxygen concentration. Non-rebreathing oxygen mask is also designed with a one-way valve to direct gas from the oxygen reservoir into the mask during inhalation. During exhalation, two one-way valves located on both sides of the mask open to release exhaled gas to the atmosphere.

[0097] For patient safety issues in the event of an oxygen source interruption or disconnection, a regular non-rebreathing oxygen respirator mask typically has one exhalation valve removed to prevent asphyxiation. The removal of this one exhalation valve is the cause of continuous room air entrainment during inhalation. Therefore, the delivery of regular non-rebreathing oxygen respirator masks is significantly less than 100% oxygen concentration, despite their design for acute or critical event patients. The result of using sub-therapeutic oxygen levels includes further deterioration of the patient's condition, leading to the application of more advanced therapeutic interventions. Remedies for this inefficient oxygen delivery device include the use of additional procedures, mechanical ventilation using endotracheal intubation. These treatments not only pose safety risks to the patient, but also incur unnecessary expense and prolong hospital stays.

[0098] The oxygen mask of the present disclosure improves patient safety and reduces or eliminates risk factors of regular non-rebreathing oxygen respirator masks associated with inefficient oxygen delivery by delivering 100% (or near 100%) Fi02, even though its oxygen flow is lower than the oxygen flow typically used for regular masks.

[0099] 11. Improved preservation of natural water vapor: Water vapor can be collected and stored in a reservoir, at least because the oxygen mask of the present disclosure can use a lower oxygen flow. The benefits of retaining water vapor include prevention of dry mouth, mucus blockage, and drying of the nasal mucosa.

[0100] 12. Reduced cost of producing oxygen masks: Regular masks can use multiple one-way valves and / or storage bags, which can result in increased production costs. The oxygen mask of the present disclosure can provide a full range of oxygen masks, including inexpensive masks. By not using one-way valves and / or storage bags, the oxygen mask of the present disclosure can reduce production costs. However, some oxygen masks of the present disclosure can include one-way valves and / or storage bags.

[0101] Additionally, the oxygen mask of the present disclosure can reduce patient healthcare costs by improving safety and preventing additional negative health events due to inefficient oxygen delivery.

[0102] The basic principles of the oxygen mask of the present disclosure can be used in a variety of applications where more efficient delivery of oxygen to a patient is desired (e.g., for better safety or effectiveness).

[0103] With reference now to the drawing, exemplary embodiments are described in further detail.

[0104] With reference now Figure 1, showing a conventional oxygen mask, generally shown at reference number 100. As shown, the conventional oxygen mask 100 includes the following elements: a mask body 110, an air inlet 120, a vent 130, a nose clip 140, and a strap attachment 150. In conventional oxygen masks, the vent is typically formed near the nasal region of the conventional oxygen mask. For example, in the illustrated conventional oxygen mask, the vent 130 is formed on the upper half of the mask body 110. When the conventional oxygen mask 100 is worn, the vent 130 will be proximate to the nasal region, the oral region, or both.

[0105] Figures 2-7 An oxygen mask embodying one or more aspects of the present disclosure is shown. Generally, the oxygen mask of the present disclosure can be lightweight, comfortable to wear, ergonomically shaped, and / or disposable.

[0106] Figure 2 An embodiment is shown in which the oxygen mask 200 includes a mask body 210, an oxygen port 220, a vent 230, a nose clip 240, and a strap attachment 250.

[0107] The generally concave mask body 210 is molded from a generally air impermeable material, such as a non-toxic, medical grade plastic polymer material. In embodiments, the mask body 210 is made of silicone or polyvinyl chloride. The material of the mask body 210 can be transparent to allow a clinician to view the patient's condition. The mask body 210 and its connections and attachments can be disposable.

[0108] The mask body 210 defines a cavity adapted to fit over the mouth and nose of a patient. The profile of the peripheral edge of the mask body 210 is contoured so as to substantially seal the surrounding facial tissue of the patient to establish an inner chamber portion or interior space. The peripheral edge can be any shape so long as it is contoured so as to substantially seal the surrounding facial tissue of the patient. The peripheral edge can be formed to include one or more recesses to allow nasal cannula to enter the interior space.

[0109] In various embodiments, the mask body further includes an interface (not shown) that can be connected to the peripheral edge of the mask body 210 to inhibit the interior space of the mask body from being heavily contaminated with room air when the oxygen mask is in use. The interface can be made of various materials, including but not limited to, a gasket, a filler, a foam, and an elastomer.

[0110] The volume of the internal space according to the present disclosure is typically less than the volume of a conventional facemask. The facemask 200 is very efficient at delivering oxygen, and therefore does not require as much internal space for oxygen storage (e.g., reservoirs) as is required for conventional facemasks. In certain embodiments, the volume of the internal space is about 25 cc to about 100 cc. Thus, the oxygen facemask 200 can be configured to store about 25 cc to about 100 cc of oxygen while the oxygen facemask 200 is being worn. In specific embodiments, the oxygen facemask 200 is configured to store about 75 cc of oxygen while the oxygen facemask 200 is being worn.

[0111] The oxygen port 220 is configured to accept a standard oxygen tube. In various embodiments, the oxygen port 220 can be configured to accept any type of oxygen tube. The oxygen port 220 can be configured to accept any combination of gases or medications with oxygen. The oxygen port 220 can be configured to accept a CO2 sampling line with an oxygen tube. The oxygen port 220 allows oxygen to flow from an oxygen source (not shown) to the internal space of the oxygen facemask 200. The oxygen port 220 is formed on the upper half of the facemask body 210. In embodiments, the oxygen port 220 is formed directly above the midline that separates the upper half and the lower half of the facemask body 220. In this manner, the oxygen port 220 is located around the patient’s nostrils when the oxygen facemask 200 is being worn, allowing oxygen to be delivered to the nasal region.

[0112] One or more vent ports 230 are disposed on the lower half of the facemask body 210, allowing gases to be expelled from the oxygen facemask. In various embodiments, the vent ports 230 are located between 1 inch and 4 inches from the bottom of the facemask body 210, about 3 inches from the bottom of the facemask body 210, or about 2 inches from the bottom of the facemask body 210. In specific embodiments, the oxygen facemask 200 includes 2 vent ports 230. The vent ports 230 are disposed on opposite sides of the facemask body 210. The vent ports are located on the facemask body 210 such that they are located below the patient’s mouth when the oxygen facemask 200 is being worn.

[0113] The vent ports 230 can comprise openings that allow for free flow without any resistance to breathing. The vent ports 230 can be integrally formed with the molded facemask body 210, or can be inserted into the facemask body 210. The vent ports can be attached or connected as accessories in various ways, e.g., with filters or / and gas valves (PEEP) or one-way valves, etc.

[0114] The oxygen mask 200 can have an adjustable nose clip 240 disposed on the upper half of the mask body 210. In embodiments, the adjustable nose clip 240 is disposed on the upper half of the mask body 210 such that the nose clip 240 is above the nose when the oxygen mask 200 is worn. The adjustable nose clip 240 can be adjusted to conform to the nose to stabilize the oxygen mask 200 on the patient's face. The adjustable nose clip 240 can be made of various flexible materials. In embodiments, the adjustable nose clip 240 is made of metal.

[0115] The oxygen mask can include any number of strap attachments 250. In the illustrated embodiment, the oxygen mask includes 2 strap attachments 250. The two strap attachments 250 are disposed on opposite sides of the mask body 210 and are integrally molded with the mask body. In various embodiments, the strap attachments 250 can be separate components from the mask body and are connected to the mask body by different methods (e.g., adhesive, fasteners, and screws). The strap attachments 250 can include holes disposed thereon to allow straps to be connected to the strap attachments 250.

[0116] Figure 3 A comparison of the conventional oxygen mask 100 shown in Figure 1 to the oxygen mask 200 shown in Figure 2 is shown. The conventional oxygen mask 100 is shown as a dashed line, while the oxygen mask 200 is shown as a solid line. Generally, the mask body 210 has a thinner profile than the mask body 110, as the mask 200 does not need as much interior space as the mask 100 due to its higher oxygen delivery efficiency. In both oxygen masks, the vent is placed differently: the vent of the oxygen mask 200 is disposed near the bottom of the mask body 210; however, the vent of the conventional oxygen mask 100 is disposed near the nose region (or middle region) of the mask body 110.

[0117] Figure 4 Another embodiment of the oxygen mask of Figure 2 is shown. The oxygen mask 200 can optionally include filters 260, which can be placed on each vent 230 or can be disposed on the oxygen mask 200 instead of on the vents 230. The filters 260 are designed to filter out various undesirable substances (e.g., pathogens), and each of the filters 260 can be any shape or size to optimize filtration while eliminating (or reducing) breathing resistance.

[0118] Figure 5Another oxygen mask of the present disclosure is described, shown as reference number 300. The oxygen mask 300 can include a mask body 310, a supplemental oxygen port 320, a nose clip 340, a strap attachment 350, an oxygen reservoir tube 360, a vent 370, and an oxygen port 380. The nose clip 340 and strap attachment 350 are in accordance with other embodiments of the present disclosure.

[0119] The mask body 310 is a mask body 210 as described above.

[0120] The oxygen port 380 is an oxygen port 220 as described above.

[0121] The supplemental oxygen port 320 is formed near or on the upper half of the mask body 310 in the mid region. The supplemental oxygen port 320 can be configured to allow an oxygen source (not shown) to be connected to the supplemental oxygen port 320. In this way, oxygen can be delivered through the supplemental oxygen port 320 and the oxygen port 380 to provide a higher O2 concentration than oxygen delivered through the oxygen port 380 alone. The placement of the supplemental oxygen port 320 can allow oxygen to be delivered directly to the interior space or carbon dioxide to be sampled directly from the interior space. In embodiments, the supplemental oxygen port 320 is formed above a midline that separates the upper half and lower half of the mask body 310 and directly above the oxygen port 380. The supplemental oxygen port 320 can be any shape (e.g., generally circular, generally oval, generally rectangular). The supplemental oxygen port 320 can have a size between 0.1 inch and 3 inch diameter (or longest distance). In one embodiment, the supplemental oxygen port 320 is circular in shape with a diameter of about 1 inch. In embodiments, the oxygen port 380 can be configured as an aerosol therapy port to allow an aerosol unit or Heliox (or other gas) therapy port to be connected to the oxygen port 380. When the oxygen port 380 is used for aerosol therapy, the oxygen supplemental port 320 can be used to deliver additional needed oxygen directly to the interior space.

[0122] A filter, positive end-expiratory pressure (PEEP), one-way valve, or other application components can be applied (connected) between the mask body 310 and the oxygen reservoir tube 360 or at the end of the oxygen reservoir tube near the vent 370. The oxygen reservoir tube 360 can be integrally formed on the molded mask body 310 or can be connected to the mask body 310 through a connection hole in the mask body 310. The oxygen reservoir tube 360 is formed on or connected to the mask body 310 near the bottom of the mask body 310 (e.g., within 3 inches of the bottom of the mask body 310). In the illustrated embodiment, the oxygen reservoir tube 360 is connected to the mask body 310 within 1 inch of the bottom. The oxygen reservoir tube 360 is adjustable and can be made of any gas-impermeable material such as a non-toxic medical grade plastic polymer material (e.g., silicone or polyvinyl chloride).

[0123] In one embodiment, the oxygen storage tube 360 can be corrugated as shown to allow for adjustment in length. By adjusting the length of the oxygen storage tube 360, the volume of the oxygen storage tube 360 can be increased and decreased. In embodiments, the total oxygen storage volume is the volume of the mask body 310 plus the volume of the oxygen storage 360. The total oxygen storage volume is configured to have a volume that is about 2 / 3 of the minute ventilation of the alveoli of the patient. The diameter of the oxygen storage tube 360 can be about 0.5 inches to about 2.0 inches, or about 0.75 inches to about 1.0 inch. The length of the oxygen storage tube 360 when fully extended can be about 1 inch to about 36 inches, or about 4 inches to about 16 inches. The length (and volume) of the oxygen storage tube 360 can be adjusted according to the mask volume, 2 / 3 of the tidal volume from the spirometry value. In the illustrated embodiment, the length of the oxygen storage tube 360 when fully extended is about 12 inches.

[0124] The distal end of the oxygen storage tube 360 (opposite the proximal end on the mask body 310) can include a vent 370 allowing gas to flow from the mask body 310 through the oxygen storage tube 360 to the external environment, and from the external environment to the oxygen body 310 through the oxygen storage tube 360. In embodiments, the distal end of the oxygen storage tube 360 has a simple opening as the vent 370. The location of the vent 370 at the distal end of the oxygen storage tube 360 allows the vent 370 to be further away from the nasal and oral regions of the patient than the oxygen mask 200 shown in FIGS. 1-3. Figures 2-4 The vent 370 can include perforations. The vent 370 can be integrally formed with the oxygen storage tube 360, or can be inserted into the oxygen storage tube 360. The diameter of the vent 370 can be less than the diameter of the oxygen storage tube 360 to create a back pressure toward the alveoli to improve oxygenation from the maximum expiratory flow rate without increasing the respiratory resistance.

[0125] Figure 6 Another embodiment of the oxygen mask of the present disclosure is provided. The oxygen mask 400 can be a nasal oxygen conservation mask. The oxygen mask 400 can include a mask body 410, an oxygen port to allow an oxygen supply 430 to deliver oxygen or other gases to the interior of the mask body 410, a strap attachment 450, an oxygen storage tube 460, and a vent 470. The strap attachment 450, oxygen storage tube 460, and vent 470 are in accordance with other embodiments of the present disclosure. The oxygen mask 400 can optionally include a nose clip (not shown) in accordance with other embodiments of the present disclosure.

[0126] In one embodiment, the oxygen mask 400 is shaped to cover the nose of the patient without covering the mouth of the patient. In this way, the oxygen supply 430 can be inserted into the oxygen port or dual port for oxygen and a sampling port for end-tidal C02monitoring located near the nasal area and between the patient's nares. The oxygen reservoir tube 460 can also be located below the oxygen port and below the nares (when worn by the patient) to allow exhaled gases from the nares to exit the oxygen mask 400 through the vent 470.

[0127] Oxygen is supplied to the oxygen mask 400 in various ways known in the art. For example, oxygen can be supplied continuously (i.e., continuous flow oxygen or "CFO" system) or periodically (e.g., pulsed). In certain embodiments, the oxygen mask is provided with a bolus of oxygen periodically, where the amount of oxygen is determined based on the medical needs of the patient. While this amount can be determined or adjusted by medical personnel based on the condition of the patient, in certain embodiments, the amount of the bolus of oxygen is about 15 cc to about 25 cc. In other embodiments, the amount of the bolus of oxygen can be less than 15 cc or more than 25 cc. The mask body 410 can form an internal space to store a bolus of oxygen (or other gas) in the internal space of the oxygen mask 400 prior to inhalation by the patient. Because the internal space of the mask body 410 is insufficient to hold the bolus (pulse) amount of oxygen, the oxygen reservoir tube 460 is often needed to increase the total storage volume of the nasal mask.

[0128] The oxygen mask 400 can utilize at least 2 oxygen delivery systems to create a bolus of oxygen in the internal space of the mask body 410. In one system, oxygen is pulsed into the internal space of the oxygen mask 410 via the oxygen supply 430. This can allow for efficient delivery of oxygen by pulsing oxygen during an expiratory pause, during which oxygen is delivered to the internal space of the mask body 410 shortly before inhalation. The pulsed oxygen system can also be used with other embodiments of the present disclosure. In another system, oxygen is delivered continuously to the internal space of the oxygen mask 410 according to other embodiments of the present disclosure.

[0129] In another embodiment, a nasal pillow mask is provided that includes one or two nasal pillow prongs configured to connect with an oxygen source. The nasal pillow mask can include any conventional nasal pillow prong known in the art, and the appropriate nasal pillow prong can be determined by medical personnel based on the condition of the patient. Each nasal pillow prong can also be configured to fit the nare of the patient to allow oxygen to be delivered directly to the nare.

[0130] The nasal pillow mask comprises one or more reservoir tubes including a vent, typically one or two reservoir tubes. In one embodiment, the mask contains only one reservoir tube which is placed in the vicinity of the user's nares area when worn. In another embodiment, the mask contains two reservoir tubes, each placed on either side, i.e., the left and right sides of the mask. In one embodiment, the vent is placed at the distal end of the reservoir tube. The reservoir tube can be configured to be adjustable in volume, such that the user or medical professional can change the volume of the reservoir as needed. Also, different types of reservoir tubes can be applied depending on the desired application, such as oxygen reservoirs for long term oxygen therapy for COPD, fixed FiO2 therapy, nebulization therapy, etc. One of ordinary skill can determine the size, shape, and design of the reservoir tube depending on the medical condition of the user. In a specific embodiment, the reservoir tube is an extendable bellows.

[0131] Referring now to the drawings Figure 7 Another oxygen mask of the present disclosure is shown as reference number 500. The oxygen mask 500 can include a mask body 510, an oxygen port 520, a vent 530, a nose clip 540, a strap attachment 550, an oral aperture 560, a nasal device port 570, a suction port 575, a flexible slit 580, and a protrusion 590. The nose clip 540 and strap attachment 550 are according to other embodiments of the present disclosure.

[0132] The generally concave mask body 510 is molded from a generally air impermeable material, such as a non-toxic, medical grade plastic polymer material. In one embodiment, the mask body 510 is made of silicone or polyvinyl chloride. The material of the mask body 510 can be transparent to allow a clinician to view the patient's condition. The mask body 510 and its connections and attachments can be disposable.

[0133] The mask body 510 defines a cavity that fits over the mouth and nose of a patient. The mask body 510 optionally includes a protrusion formed in the interior space of the mask. In embodiments, the protrusion 590 can extend from the interior surface of the mask body to form a partial divider. The protrusion 590 is formed at a location on the mask body 510 such that the protrusion 590 at least partially divides the patient's nose and mouth. Thus, the protrusion 590 can be formed between the location of the oral aperture 560 and the top of the mask body 510. The protrusion 590 can have a variety of lengths, for example, from about 0.1 inches to about 3 inches. In the illustrated embodiment, the protrusion 590 is about 1.5 inches.

[0134] The peripheral edge of the mask body 510 is as described above for the peripheral edge of the mask body 210.

[0135] In various embodiments, the oxygen port 520 can be configured to accept any type of oxygen tube. In embodiments, the oxygen port 520 is a Luer-lock port. The oxygen port 520 allows oxygen to flow from an oxygen source (not shown) to the interior space of the oxygen mask 500. The oxygen port 520 is formed on the upper half of the mask body 510, for example on either side of the mask body 520. In this manner, when the oxygen mask 500 is worn, the oxygen port 520 is located to one side of the patient’s nares to allow oxygen to be delivered to the nasal region. In specific embodiments, the oxygen port 520 is formed on the left side of the mask (i.e., the right side of the patient). Further, as a Luer-lock port, the oxygen port 520 can also be used to sample carbon dioxide using a catheter. Thus, respiration (e.g., CO2 waveform) can be monitored for apneic conditions, including conditions that can lead to fatal hypoxia.

[0136] One or more vent ports 530 are disposed on the lower half of the mask body 510 to allow gas to be expelled from the oxygen mask. In various embodiments, the vent ports 530 can be located 1 inch to 4 inches from the bottom of the mask body 510, about 3 inches from the bottom of the mask body 510, or about 2 inches from the bottom of the mask body 510. In specific embodiments, the oxygen mask 500 includes two vent ports 530. The vent ports 530 are disposed on opposite sides of the mask body 510. The vent ports are located on the mask body 510 such that when the oxygen mask 500 is worn, they are located below the patient’s mouth.

[0137] The vent ports 530 can include perforations that allow gas to flow freely. The vent ports 530 can be integrally formed with the molded mask body 510 or can be inserted into the mask body 510.

[0138] An oral hole 560 is formed near the middle region or upper half of the mask body 560. When the oxygen mask 500 is worn, the oral hole 560 is positioned over the patient's mouth to provide access to the patient's mouth. In this manner, surgical tools can access the patient's mouth through the oral hole 560. In one embodiment, the oral hole 560 is formed directly above the midline that separates the upper half and lower half of the mask body 510. The oral hole 560 can be any shape (e.g., generally circular, generally oval, generally rectangular) as long as the oral hole can be formed in the mask body 510. The oral hole 560 can have a size of 0.1 inch to 3 inches in diameter (or longest length). In one embodiment, the oral hole 560 is circular and has a diameter of about 3 / 4 inch. An optional insulator (not shown) can be placed within the oral hole to prevent the free flow of gas. The optional insulator can be made of any suitable material including, but not limited to, rubber, silicone, and foam. The optional insulator has a hole to allow surgical tools to pass through the oral hole 560 and the optional insulator itself. In embodiments, the optional insulator is a septum having a continuously perforable membrane.

[0139] The oxygen mask 500 can optionally include one or more nasal instrument ports 570 formed on the upper half of the mask body 510. In one embodiment, the oxygen mask 500 includes two nasal instrument ports, as shown in Figure 6 In another embodiment, the oxygen mask 500 includes one nasal instrument port. Each nasal instrument port 570 is formed on the upper half of the mask body 510 such that each nasal instrument port 570 allows access to the patient's nose and nostrils when the oxygen mask 500 is worn. In this manner, nasal instruments can access the patient's nose and nostrils when the oxygen mask 500 is worn. Similar to the oral hole 560, the nasal instrument port 570 can have an optional insulator. In embodiments, the optional insulator is a septum having a continuously perforable membrane.

[0140] The oxygen mask 500 can optionally include one or more suction ports 575 formed on the mask body 510. In one embodiment, the oxygen mask 500 includes one suction port 575, as shown in Figure 6 Generally, the suction port 575 is formed on a side that is toward the center region of the oxygen mask 500. The suction port 575 is configured to allow a suction device (not shown) to be connected to the suction port 575. In this manner, the suction device can remove liquid or other materials from the interior space. The suction port 575 can be formed in any manner known in the art. In one embodiment, the suction port 575 includes a septum having a continuously perforable membrane.

[0141] The oxygen mask 500 may optionally include one or more flexible slits 580 formed on the lower half of the mask body 510. In one embodiment, the oxygen mask 500 includes two flexible slits 580, such as... Figure 6 As shown, the number of slits is not important. Therefore, a person skilled in the art can determine the number as needed. The flexible slit 580 can be of any shape (e.g., straight, curved, and V-shaped). In one embodiment, the flexible slit 580 is V-shaped. The flexible slit 580 is formed on the lower half of the mask body 510. For example, the flexible slit 580 is formed below the mouth opening, as shown in the illustrated embodiment. The flexible slit 580 can make the mask body 510 more flexible.

[0142] In one embodiment, an infection-preventing face shield is provided, which can be used in various medical procedures, such as endoscopy. Typically, the face shield body is made of infection-preventing materials known in the art, such as microfiber fabrics. The face shield body is opaque except for the window area.

[0143] Figure 8 Showing Figure 7 Another embodiment of the oxygen mask. Optional recesses 595 are formed on the peripheral edge of the mask body 510. Recesses 595 are configured and / or shaped to allow direct access of the nasal cannula to the nasal region of the internal space while minimizing leakage from the internal space to the external environment. Recesses 595 are located on the upper portion of the mask body 510. Recesses 595 may be located 1 to 4 inches from the bottom of the mask body 510, approximately 3 inches from the bottom of the mask body 510, or approximately 2 inches from the bottom of the mask body 510. In one embodiment, the oxygen mask 500 includes two recesses 595. Recesses 595 are located on opposite sides of the mask body 510. In one embodiment, an oxygen source (not shown) connected to a nasal cannula can supply oxygen to the patient individually. In one embodiment, an oxygen source (not shown) connected to a nasal cannula, combined with an oxygen source (not shown) connected to an oxygen port 520, can supply oxygen to the patient. In one embodiment, the aperture 560 may include a rubber insulator and may also be surrounded by a transparent material (e.g., a plastic polymer) to allow observation of the internal space of the oxygen mask of this disclosure through the transparent material. In one embodiment, a pad or other sealing structure may be included along the edge of the oxygen mask of this disclosure for sealing the mask to the patient's face and for preventing air leakage.

[0144] In one embodiment, the oxygen mask of the present disclosure can be used with a nasal cannula instead of with an oxygen source connected through the oxygen port 520. In this embodiment, the oxygen mask of the present disclosure does not include the oxygen port 520, and oxygen (or other medication) is delivered to the patient only through the nasal cannula, which enters the interior space of the mask through the recess 595. In this way, the oxygen mask of the present disclosure can simply be applied to a patient who is already using a nasal cannula, and the oxygen mask can be removed after use while the patient is still using the nasal cannula. This can be advantageous for patients undergoing surgical procedures, as many patients can require a nasal cannula both before surgery and during recovery after surgery, and the oxygen mask of the present disclosure can be conveniently applied and removed.

[0145] Example

[0146] Example 1: Comparative Study

[0147] In this example, the oxygen mask of the present disclosure is compared to a nasal cannula and a nasal reservoir cannula (i.e., an oxymizer) to understand how much oxygen is delivered to the alveoli and how much oxygen is wasted with each breath cycle.

[0148] There are three phases to each breath cycle: inspiration, expiration, and expiratory pause. During a normal spontaneous breath cycle, all three phases have equal time. Thus, each phase lasts one-third of the normal breath cycle. During the first half of the inspiration phase, oxygen reaches the alveoli. During the first half of the inspiration phase, 2 / 3 of the tidal volume reaches the alveoli. During the other phases of the breath cycle, the oxygen that is normally supplied is wasted.

[0149] A. Nasal Cannula: The oxygen flow rate is 4 L / min and the patient's respiratory rate is 20 breaths / min. The tidal volume is 450 cc. The tidal alveolar ventilation is 300 cc. Thus, the oxygen flow rate / breathing cycle is about 200 cc (4000 cc / 20 breaths / min) and the oxygen flow rate / stage is about 66.6 cc (200 / 3 cc). During inspiration, about 33.3 cc of 100% oxygen reaches the alveoli, and 56 cc of 100% oxygen from 21% oxygen of 267 cc of room air (300 cc - 33.3 cc = 266.7 cc and 266.7 x 21 / 100 = 56 cc). Thus, 89 cc of 100% oxygen is delivered to the alveoli per breath, which is 30% (89 / 300 x 100 = 30%). Per minute, about 666.6 cc (33.3 cc x 20 breaths / min = 666.6 cc) reaches the alveoli out of a total of about 4000 cc of oxygen supplied, resulting in about 17% utilization and about 83% oxygen waste. The proportion of inhaled oxygen delivered by a standard nasal cannula at a flow rate of 4 L / min is theoretically about 30%.

[0150] B. Nasal reservoir cannula (Oxymizer): The reservoir cannula is an oxygen conservation device ("OCD"). It can store 20 ml of oxygen during exhalation and make oxygen available for the start of the next inspiration. The oxygen flow rate is 4 L / min and the patient's respiratory rate is 20 breaths / min. The tidal volume is 450 cc. The alveolar ventilation is 300 cc. During inspiration, the first half of the inspiration time is responsible for alveolar ventilation, delivering about 33.3 cc of oxygen from the continuous flow of oxygen. During the first half of inspiration, a total of about 105 cc of 100% (or close to 100%) oxygen is delivered to the alveoli (20 cc from the reservoir + 33.3 cc from the continuous flow + 52 cc from 21% room air). Per minute, about 1066 cc of the provided oxygen is used for alveolar oxygenation out of 4000 cc of oxygen provided, resulting in 27% utilization and about 73% oxygen waste. The proportion of inhaled oxygen delivered by a reservoir nasal cannula is theoretically about 35%.

[0151] C. Oxygen mask of the present disclosure: The sealed oxygen mask can save about 66.6 cc of oxygen during the expiratory pause. At the early stage of the inspiratory phase, about 66 cc of nearly 100% oxygen bolus and about 33.3 cc of oxygen from the continuous oxygen flow and 42 cc of oxygen from the room air reach the alveoli, for a total of about 141.4 cc of 100% (or nearly 100%) oxygen per breath. About 1998 cc of oxygen reaches the alveoli per 4000 cc of oxygen delivered. Thus, about 50% of fresh oxygen from a 4 L / min flow is wasted. The percentage of inhaled oxygen delivered via the oxygen mask of the present disclosure is theoretically about 47%.

[0152] The results of this comparative study are shown in Table 1 below.

[0153] Table 1. Comparison of O2 utilized and the proportion of inhaled O2 per 4000 cc of O2 supplied.

[0154] Reference articles and textbooks Theoretical calculations Measured by end-tidal O2 (FeO2) The amount of O2 utilized can be estimated by defining “X” as the oxygen supply for each respiratory phase of the respiratory cycle and using the following equations (using X = 66.6 cc as an example): X = 66.6 cc of oxygen, • Nasal cannula: (1 / 2) X = 33.3 cc of utilized oxygen plus room air oxygen, • Reservoir nasal cannula: (1 / 2) X + 20 cc of reservoir oxygen = 53.3 cc of utilized oxygen plus room air, • Oxygen mask of the present invention: (1 / 2) X + X = 99.9 cc of utilized oxygen plus room air oxygen, The O2 flow required to achieve 30% FiO2 using the oxygen mask of the present disclosure can be determined using known TV and RR values. For example, when TV is 450 cc and RR is 20 cycles / minute, then the total volume delivered during the first half of inspiration is 300 (450 cc x (2 / 3) = 300 cc). If “Y” represents the amount of 100% oxygen delivered to the alveoli to achieve 30% FiO2, then the necessary flow rate can be calculated as follows: 100% x (Y / 300 cc) = 30% Y x 100% = 30% x 300 cc Y = 90 cc Accordingly, the amount of 100% oxygen required to be delivered to the alveoli to achieve a Fi02 of 30% is 90 cc. The oxygen mask of the present disclosure can deliver oxygen according to X + ½X + RA, where X is the amount of 100% oxygen stored in the reservoir during expiratory pause and then delivered to the alveoli during the first half of inspiration, ½X is the amount of 100% oxygen delivered from the continuous flow oxygen source during the first half of inspiration, and RA is the amount of 100% oxygen from room air at 21% oxygen. Accordingly, the amount of 100% oxygen required to be stored in the reservoir during expiratory pause can be calculated as follows: X + ½X + RA = 90 cc of 100% oxygen (3 / 2)X = 90 cc - RA Since RA is approximately 44 c, there is a Fi02 of 30%: (3 / 2)X = 90 cc - 44 cc = 46 cc X = (2 / 3) (46 cc) X = 30.6 cc During expiratory pause, 30.6 cc of 100% oxygen is stored in the reservoir, and 30.6 cc of 100% oxygen is delivered per breath phase. Given that there are 3 breath phases, 91.8 cc of 100% oxygen is delivered per breath cycle (30.6 cc / phase x 3 phases / cycle = 91.8 cc / cycle). With a RR of 20 cycles / minute, the required flow rate is 1836 cc / min (91.8 cc / cycle x 20 cycles / minute = 1836 cc / min). In other words, for this case, the oxygen mask of the present disclosure requires a flow rate of approximately 1.8 L / min. Considering that a nasal cannula requires an oxygen flow rate of 4 L / min for a Fi02 of 30%, the oxygen mask of the present disclosure saves over 50% of oxygen compared to a nasal cannula.

[0155] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" can include plural forms unless the context clearly indicates otherwise. The terms "comprises," "comprising," "includes," "including," and "has," "having," their derivatives, and the like, are inclusive (i.e., open-ended) rather than exclusive (i.e., closed-ended) and specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order in which they are described. It is also to be understood that additional or alternative steps can be employed.

Claims

1. An oxygen mask for use with spontaneously breathing patients, comprising: a mask body defining a cavity that covers the mouth and nose of a patient, an oxygen port formed in an upper half of the mask body, an internal space between the oxygen port and the vent, the internal space configured to store about 20 to 100 cubic centimeters of oxygen during expiratory pauses of the patient's breathing cycle, a vent formed in a lower half of the mask body and remaining open during expiration, during expiratory pauses, and during inspiration; wherein during expiratory pauses, continuous oxygen flow through the oxygen port expels exhaled gases in the internal space through the vent and fills the internal space with fresh oxygen, such that fresh oxygen is delivered with stored oxygen at the start of the next inspiration, thereby reducing oxygen dilution.

2. The oxygen mask of claim 1, wherein the oxygen mask further comprises an attachable oxygen reservoir tube that is fluidly connected to the internal space, the oxygen reservoir tube increasing the total storage volume when attached.

3. The oxygen mask of claim 1, wherein the internal space has a volume of about 50 to 75 cubic centimeters when the oxygen reservoir tube is not attached.

4. The oxygen mask of any of the preceding claims, wherein the oxygen mask delivers an inspired oxygen concentration (FiO2) of 50-55% when oxygen is supplied at a flow rate of 4 L·min 1.

5. The oxygen mask of any preceding claim, wherein the vent directs exhaled gases of the patient downward and away from the patient's airway.

6. The oxygen mask of any preceding claim, wherein the mask body is made of a flexible, transparent, medical grade polymer.

7. An oxygen mask, comprising: one or two nasal prongs configured to be placed within the patient's nostrils and connected to an oxygen source; and a mask body defining an internal space that overlies the patient's mouth and nose, and the mask body having no oxygen port thereon, a vent formed in a lower half of the mask body; wherein the internal space has a volume of about 20 to 100 cubic centimeters and is configured to store oxygen delivered from the nasal prongs during expiratory pauses and to expel exhaled gases through the vent, such that stored oxygen is delivered with continuous nasal prong flow at the start of inspiration.

8. The oxygen face mask of claim 7, wherein the nasal cannula airflow has a flow rate of 2 to 4 L min. ¹.

9. The oxygen mask of claim 7 or 8, wherein the oxygen mask further comprises a detachable oxygen reservoir tube connected to the mask body to increase the total storage volume.

10. The oxygen face mask of any one of claims 7 to 9, wherein the oxygen face mask delivers a FiO2 of 50-55% at the onset of inhalation when oxygen is supplied at 4 L·min ¹.

11. An oxygen mask, comprising: a mask body configured to cover only the patient's nose, an oxygen port formed in an upper half of the mask body, a corrugated, telescoping storage tube integral with the mask body and extending downward, the mask body and storage tube together defining an internal space having a total volume of less than 100 cubic centimeters; wherein during expiratory pauses, continuous oxygen flow expels exhaled gases in the internal space and fills the internal space with oxygen, such that stored oxygen is delivered with continuous oxygen flow at the start of the next inspiration, thereby reducing oxygen dilution.

12. The oxygen mask of claim 11, wherein the storage tube is corrugated and axially telescoping to increase the volume of the internal space when needed.

13. The oxygen face mask of claim 11 or 12, wherein the volume of the interior space is about 25 to 75 cubic centimeters when the reservoir tube is in the collapsed state.

14. The oxygen mask of any one of claims 11 to 13, wherein the oxygen mask delivers a FiO2 of 50-55% when the oxygen flow rate is 4 L·min ¹.

15. A method of delivering a therapeutic oxygen dose to a self-ventilating subject comprising: a) placing the oxygen face mask of claim 1 on the face of the subject; b) 2 to 4 L·min ¹ Oxygen supplied; c) expelling exhaled gases and storing about 20 to 100 cubic centimeters of oxygen in the interior space during each expiratory pause; and d) delivering the stored oxygen with a continuous flow of oxygen at the onset of the next inspiration, thereby achieving a blood oxygen saturation (Sp02) of at least 96% without increasing the flow of oxygen.

16. The method of claim 15, wherein step b) further comprises attaching an oxygen storage tube at Fi Below 0.55, attach oxygen storage tube.

17. The method of claim 15 or 16, wherein the subject’s peak inspiratory flow exceeds 60 L·min 1 during periods of dyspnea, and the method maintains Fi of at least 0.

50.

18. The method of any one of claims 15 to 17, wherein the oxygen face mask is used while performing an upper gastrointestinal endoscopy, and the subject remains self- ventilating.

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