Patent Description:
In view of infectious respiratory diseases, such as coronavirus (and specifically the COVID-<NUM> pandemic), an effort is being made to greatly expand access to mechanical ventilation in medical facilities. In addition to increasing production of various ventilators, efforts abound to adapt many different types of ventilators to treat patients. A key requirement of such ventilators is the need to provide controlled supplemental oxygen between <NUM>% and <NUM>% fraction of inspired oxygen (FiO<NUM>) or fractional oxygen. This is currently not doable with most ventilators that can be produced in very high quantities, such as sleep apnea treatment ventilators or CPAP machines.

For example, the Philips/Respironics Trilogy EVO ventilator can include an oxygen blending module (OBM) option, but world-wide supply chain limitations make it difficult to meet demand for such ventilators with OBMs, which is projected to be in the <NUM>,<NUM> to <NUM>,<NUM> per month range. As an alternative to ventilators such as the Trilogy EVO with OBM, there is a need to create a controlled FiO<NUM> between <NUM>% and <NUM>% for use as in ventilators that lack OBMs.

The following discloses certain improvements to overcome these problems and others.

<CIT> describes a ventilator device and system comprising a rotating compressor, preferably a drag compressor, which, at the beginning of each inspiratory ventilation phase, is accelerated to a sufficient speed to deliver the desired inspiratory gas flow.

In one aspect, there is provided a gas delivery apparatus according to claim <NUM>.

In another aspect, there is provided a mechanical ventilation method according to claim <NUM>.

One advantage resides in providing a mechanical ventilator with an adjustable FiO<NUM> setting.

Another advantage resides in providing a substantially constant, clinician controlled FiO<NUM>.

Another advantage resides in providing an adapter for existing mechanical ventilators with OBMs.

Another advantage resides in providing a ventilator with a reservoir of mixed air and oxygen.

Another advantage resides in provider a ventilator with a reservoir of mixed air in fluid communication with an inlet of a ventilator. Another advantage resides in providing a gas delivery apparatus that enables any pressure-support ventilator that does not have a designated oxygen mixing method or apparatus to deliver oxygenated air, preferably with a user control for adjusting the fraction of oxygen.

Another advantage resides in providing a gas delivery apparatus and corresponding method for retrofitting an existing ventilator to deliver oxygenated air.

The disclosure may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the disclosure.

Embodiments disclosed herein enable clinicians to provide controlled FiO<NUM> into any pressure support ventilator. The main elements of one non-limiting illustrative gas delivery apparatus or method include: (<NUM>) connection conduits/hoses for air and oxygen, such as from the hospital wall supply; (<NUM>) an oxygen blender/blending method of some sort; (<NUM>) a flow control method for either mixed gas or each gas separately; (<NUM>) an optional algorithm communicated to the user or clinician to allow them to set the correct flows; (<NUM>) a connector to a patient circuit; (<NUM>) a patient circuit such as a <NUM>, <NUM>' standard patient circuit; (<NUM>) a 'Y' connection that connects <NUM> patient circuits, a connection to the ventilator and optionally a Positive End Expiratory Pressure (PEEP) valve; (<NUM>) a special connector that engages the pneumatic inlet to the ventilator that can connect to the 'Y' connection; (<NUM>) a serial section of two tubes, such as <NUM>, <NUM>' tubes, connected to the 'Y' connection; and (<NUM>) optionally a PEEP valve as a safety measure to limit the pressure change at the ventilator inlet.

The approach described herein involves benefits of, inter alia, (<NUM>) leveraging existing capabilities and materials available in hospitals (i.e. wall O<NUM> and Air; O<NUM>-Blenders); (<NUM>) minimizing the use of new parts, using readily available respiratory parts (i.e., <NUM> tubing, connectors, etc.); and being applicable to other platforms such as CPAP or BiPAP machines like the Philips/Respironics DreamStation (available from Koninklijke Philips NV, Eindhoven, the Netherlands).

Some non-limiting embodiments disclosed herein provide methods of making and using the systems described above. For example, the main elements of the disclosure described above may be connected with standard parts and fittings such that the user or clinician would be able to assemble the system according to a diagram and/or appropriate instructions.

These and other objects, features, and characteristics of the present disclosure, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and any appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures.

The disclosed gas delivery apparatuses and methods effectively replace the atmospheric gas drawn into the inlet of the vent with gas of the clinician specified FiO<NUM>. By using this approach, the ventilator will operate normally since the goal is to provide the gas mixture at atmospheric pressure. In this fashion, any mode or function of the ventilator will continue to operate as normal.

The system includes a means of providing a controlled FiO<NUM> from hospital wall gas supplies, such as the use of rotameters, blenders, high flow nasal therapy (HFNT) devices, etc. that can supply up to <NUM>/min. The system also includes a means to inform the clinician of the gas flow setting, which is equal to mean leak flow over a breath.

The system also includes a means of porting that gas to the inlet of the ventilator, such as a connection from the wall gas supply to a <NUM>', <NUM> patient circuit attached to a "Y. " The "Y" may be attached to a special fitting that connects to the specific ventilator (e.g., a Philips/Respironics Trilogy EVO ventilator, Trilogy ventilator, or DreamStation BiPAP - each having an appropriate interface fitting).

The system also includes a reservoir that is freely open to the atmosphere on one end that holds up to <NUM> (although other capacities are contemplated) and is connected to the other branch of the "Y". This reservoir can be comprised of, for example, <NUM>' of <NUM> tubing, or a single <NUM>' of tubing, coupled to a <NUM> bladder open on the opposite end from the connection to the tubing. The system may also include preferential use of a <NUM> circuit between the vent and the patient, which may include humidification, and which would accommodate all other normal aspects of a single or dual-limb limb patient interface.

In some embodiments, the system delivers high flows to the patient circuit due to the use of a fixed-orifice exhalation valve in a single-limb circuit, which leaks flow proportional to circuit pressure. Depending on ventilator settings, this typically requires flows that are a factor of, for example, <NUM>-<NUM> times patient minute volume (for example, a typical adult has a patient minute volume of <NUM>-<NUM>/min).

A basic description of each part of an exemplary embodiment will now be provided.

Wall Gas-Supplies of air and oxygen of fifty psi each are provided at each bed in the hospital. They can be accessed with standard fittings. These pressures can have a wide tolerance is U. medical facilities, particularly in situ when high volumes of gas are being used during a pandemic. Also, supply pressures may vary widely at medical facilities around the world.

Gas FiO<NUM> Delivery-There are a number of methods for gas blending. One method uses a Traditional Gas Blender and Rotameter/Flowmeter - The only restriction on this approach is the availability of blenders in hospitals may be limited and the flow meter must be able to do up to <NUM>/min, which is higher than what is normally used in such devices. Setting the FiO<NUM> requires merely dialing in the desired setpoint on the blender face. Another method uses a HFNT Device, which are high flow devices that can deliver constant flow rates at specified FiO<NUM> values. They can be connected as the source to the inlet of the supply tube. Another method uses a Dual-Rotameter. This approach requires separate rotameters on the air and oxygen supplies that then allows the gas to be blended downstream. Setting the FiO<NUM> by the user suitably employs an empirical or calculated table to allow setting of the two flows to allow the total to achieve a specified FiO<NUM> at a given bulk flow.

Connector-This is a fitting that connects the blending outlet to the <NUM>', <NUM> patient circuit. Its form would be dependent on the method chosen for blending.

<NUM>', <NUM> Tube and "Y" Assembly-Blended gas would enter, via the Connector, a standard <NUM>' circuit attached to a "Y". At this point, the gas should substantially be near atmospheric pressure, which is desired at the inlet to the vent. The "Y" would then connect to the Special Fitting. A second limb of the <NUM>', <NUM> tubing would then be attached to the other leg of the "Y". This leg allows gas to accumulate upstream from the vent when vent flow is less than blender flow (during exhalation), allowing a reservoir from which to draw gas back in for use when the vent flow exceeds the blender flow (occurs during inspiration).

Reservoir-Extra volume at the end of the second tube. Its volume should be <NUM>, allowing a total accumulation volume of <NUM> (a <NUM>', <NUM> tube has a volume of about <NUM>), which is required to cover most ventilation cases. It is imperative that the reservoir be vented to atmosphere so as not to allow pressure to build up in front of the vent. It is also preferable that this volume be shaped in the form of a tube in order to limit the FiO<NUM> gas from mixing either with atmospheric air, or with the mixture that previously resided in this reservoir.

Special Fitting-This is a fitting that would allow the "Y" of the dual-limb circuit to be connected to the inlet of the ventilator with a seal so that no atmospheric air can leak into the vent. Such a fitting could be adapted for each ventilator that uses this blended oxygen approach. This technology could be applied to any ventilator or sleep therapy device for which a Special Fitting can be adapted.

Setting the Flow Rate-The system uses a model to predict the required flow rate based on an estimation of the ventilator minute volume. The ventilator minute volume is defined as <MAT> where V̇ventilator is the minute volume of the ventilator (L/min), VTventilator is the volume delivered by the vent per breath (L/breath) and Ψ is the patient breath rate (breath/min). The ventilator minute volume, also known as the average leak flow, is often calculated and displayed by the ventilator.

The blended gas flow rate could be equal to the ventilator minute volume times a factor like <NUM>. The actual factor value is suitably derived empirically, but preliminary data indicate that this approach is effective. The system may also be configured to communicate this value to the clinician. The ventilator may calculate and display this value, which can be accomplished via a software change, or it could be provided in accompanying literature. Because the value may be estimated just from delivered pressure, however, it can also be calculated or tabulated for the clinician very easily.

With reference to <FIG>, <FIG>, and <FIG>, a mechanical ventilator system <NUM> for providing ventilation therapy to an associated patient P is shown. As shown in <FIG> and <FIG>, the system <NUM> includes a mechanical ventilator <NUM>, which can be a continuous positive airway pressure (CPAP) device, a bilevel positive airway pressure (BIPAP) device, or any other suitable mechanical ventilator (e.g., a Philips/Respironics Trilogy EVO ventilator, available from Koninklijke Philips NV). The mechanical ventilator <NUM> includes an atmospheric inlet <NUM> for drawing in atmospheric gas, and an outlet <NUM> connectable with a patient breathing circuit <NUM> to delivery mechanical ventilation to the patient P. The patient circuit <NUM> includes typical components for a mechanical ventilator, such as an inlet line <NUM>, an optional outlet line <NUM> (this may be omitted if the ventilator employs a single-limb patient circuit), a patient port <NUM>, an exhalation valve <NUM> (this may be omitted if the ventilator employs a dual-limb patient circuit), and one or more breathing sensors (not shown), such as a gas flow meter, a pressure sensor, end-tidal carbon dioxide (etCO<NUM>) sensor, and/or so forth. The patient port <NUM> can be variously embodied. For non-invasive ventilation, the patient port <NUM> is suitably a mask strapped to the patient's face. For invasive ventilation, the patient port <NUM> may be an endotracheal tube, tracheostomy tube, or so forth. The disclosed approaches for delivering mixed air and oxygen gas to the atmospheric inlet <NUM> of the mechanical ventilator <NUM> may be generally employed in conjunction with any patient port design.

<FIG>, <FIG>, and <FIG> also show a gas delivery apparatus <NUM>, <NUM> configured to deliver mixed air and oxygen gas to the atmospheric inlet <NUM> of the mechanical ventilator <NUM>. The atmospheric inlet <NUM> is also variously referred to herein as the inlet <NUM> of the mechanical ventilator <NUM> or as the pneumatic inlet <NUM> to the ventilator. The mechanical ventilator <NUM> is designed to draw atmospheric air in via the inlet <NUM> which is delivered to the outlet <NUM> to ventilate the patient. The inlet <NUM> may include threading or some other attachment for receiving a filter that removes particulates and optionally other contaminants from the drawn air. The mechanical ventilator <NUM> includes an electronic processor <NUM>, and a display <NUM>.

The gas delivery apparatus <NUM> connects with this inlet <NUM> via a special fitting <NUM> to instead supply mixed air and oxygen gas at (about) atmospheric pressure. As shown in <FIG>, <FIG>, and <FIG>, the gas delivery apparatus <NUM> is connected with an oxygen supply <NUM> and an air supply <NUM>, both of which are suitably standard wall oxygen <NUM> and wall air <NUM> supply outlets mounted on a wall of a room of a medical facility where the ventilation system <NUM> is deployed. Such wall oxygen and wall air (as well as wall vacuum) are ubiquitous in hospitals and other medical facilities. The wall oxygen <NUM> supplies oxygen at (nominally) <NUM> pounds per square inch (<NUM> psi) according to common practice in the United States; however, it is common for the actual oxygen supply pressure to vary somewhat depending on extent of usage and other factors (e.g., the supply of oxygen gas may be <NUM> psi + or - <NUM> psi). Likewise, the wall air <NUM> supplies air at <NUM> psi; however, it is common for the actual air supply pressure to vary somewhat depending on extent of usage and other factors (e.g. the supply of air may be <NUM> psi + or - <NUM> psi). The nominal pressure may be different in various localities. For example, in Europe the oxygen supply is typically nominally around <NUM>-<NUM> psi.

In the gas delivery apparatus, the oxygen supply <NUM> and the air supply <NUM> are connected with a connecting device <NUM> that connects the oxygen and air supplies with the mechanical ventilator <NUM> (e.g., via the special fitting <NUM> of the gas delivery apparatus in the illustrative examples). The connecting device <NUM> is configured to deliver mixed air and oxygen gas to the atmospheric inlet <NUM> of the mechanical ventilator <NUM> (by way of the special fitting <NUM> in the illustrative examples). To do so, the connecting device <NUM> includes a mixer <NUM> configured to mix oxygen gas from the oxygen supply <NUM> and air from the air supply <NUM> to generate a mixture of mixed air and oxygen gas. As shown in <FIG>, the mixer <NUM> comprises a blender or a flow nasal therapy device (FNTD) <NUM>. By contrast, <FIG> shows an embodiment in which the mixer <NUM> includes a first rotameter <NUM> connected to control a flow rate of oxygen from the oxygen supply <NUM>, and a second rotameter <NUM> connected to control a flow rate of air from the air supply <NUM>. An outlet <NUM> of the first rotameter <NUM> and an outlet <NUM> of the second rotameter <NUM> are connected together form the mixed air and oxygen gas. These are merely illustrative embodiments, and the mixer <NUM> may be otherwise embodied so as to combine oxygen from the wall oxygen <NUM> and air from the wall air <NUM> to produce the mixed air and oxygen gas.

The connecting device <NUM> further includes a user control <NUM> allowing a medical professional to adjust a fraction of oxygen in the mixed air and oxygen gas. As shown in <FIG>, the user control <NUM> comprises a user control (e.g., a knob, a button, a slider, and so forth) of the blender or FNTD <NUM>. In <FIG>, the user control <NUM> suitably includes two flow control knobs - one for controlling the oxygen (O<NUM>) rotameter <NUM> and the other for controlling the air rotameter <NUM>. The mixer <NUM> is configured to mix oxygen from the oxygen supply <NUM> with air from the air supply <NUM> at a controlled total rate of a flow of mixed air of approximately <NUM>-<NUM>/min. This rate can be adjusted with the user control <NUM>.

The connecting device <NUM> further includes a flow path of the mixed air and oxygen gas from an outlet connector <NUM> of the mixer <NUM> to the atmospheric inlet <NUM> of the mechanical ventilator <NUM>. In <FIG>, this flow path of the mixed air and oxygen gas to the atmospheric inlet <NUM> of the mechanical ventilator <NUM> includes a <NUM>', <NUM> tube <NUM> connecting at one end with a mixer outlet connector <NUM> and at the other end with the special fitting <NUM>. As will be explained, the flow path of the mixed air and oxygen gas to the atmospheric inlet <NUM> of the mechanical ventilator <NUM> further includes a branch connector <NUM>, e.g. an illustrative "Y" connector <NUM>, or a "T" connector, or so forth. The illustrative branch connector <NUM> has three ports: a port P1 connected with the <NUM>', <NUM> tube <NUM> to receive the mixed air and oxygen gas from the mixer <NUM>; a port P2 connected with a reservoir <NUM> to be described; and a port P3 connected with an inlet of the special fitting <NUM> and thus serving to flow the mixed air and oxygen into the atmospheric inlet <NUM> of the mechanical ventilator <NUM> via the fitting <NUM>.

The connecting device <NUM> includes the reservoir <NUM> which is configured to hold a volume of the mixed air and oxygen gas. The reservoir <NUM> is connected with the flow path <NUM>, <NUM> of the mixed air and oxygen gas to the atmospheric inlet <NUM> of the mechanical ventilator <NUM> by way of connection with the port P2 of the branch connector <NUM>. The reservoir <NUM> is also open to atmosphere at a port PA. The illustrative reservoir <NUM> of <FIG> and <FIG> includes a bladder <NUM> connected with the port P2 of the branch connector <NUM> by way of a <NUM>', <NUM> tube <NUM>. The volume of the mixed air and oxygen gas held in the reservoir <NUM> of <FIG> and <FIG> is thus the sum of the volume of the bladder <NUM> and the volume contained by the tube <NUM>.

In the embodiment of <FIG>, the illustrative reservoir <NUM> omits the bladder and instead includes two <NUM>', <NUM> tubes <NUM>-<NUM> connected in series, with one end connected to port P2 of the branch connector <NUM> and the other end open to air. Hence, the volume corresponds to the volume of <NUM>-feet of <NUM> diameter tubing. More generally, embodiments corresponding to <FIG> comprise a tube <NUM>-<NUM> having: a first end E1 connected with the flow path <NUM>, <NUM> of the mixed air and oxygen gas to the atmospheric inlet <NUM> of the mechanical ventilator <NUM>; and a second end E2 open to atmosphere. The volume is thus <MAT> where d is the diameter of the inner lumen of the tube and L is the total length of the tube. In embodiments in which the length L is large (e.g., <NUM>-feet long in the embodiment of <FIG>), the tube <NUM>-<NUM> may be coiled up to reduce its size. An advantage of using a tube <NUM>-<NUM> as the reservoir <NUM> is that if the tube lumen diameter d is sufficiently small then gas inside the tube will be mixed primarily by diffusion, rather than by convection, which can increase the uniformity of the oxygen fraction in the mixed gas contained in the reservoir <NUM>.

The port PA may be an opening to atmosphere of the bladder <NUM> (<FIG> and <FIG>), or may be the open end E2 of the tube <NUM>-<NUM> (<FIG>). While the reservoir <NUM> is open to atmosphere via the port PA, it is to be understood that this does not preclude inclusion of a dust filter or the like at the port PA (or elsewhere, such as near the special fitting <NUM>) which may introduce some flow resistance, so long as that flow resistance is not so large as to prevent the pressure of the mixed oxygen and air gas inside the reservoir <NUM> from reaching beyond a few cmH<NUM>O above or below ambient atmospheric pressure. For example, the port PA may have a mesh filter, a foam filter, or the like to suppress ingress of dust or other debris into the reservoir <NUM>. Furthermore, in the embodiment of <FIG>, if the tube <NUM>-<NUM> is coiled up, then this coiled-up tube may optionally be placed inside a mesh bag or the like (not shown) so long as the mesh of the bag does not substantially impede air flow into, or mixed gas flow out of, the port PA. An advantage of such a mesh bag is that it may reduce the potential for a nurse or other medical professional who notices the open end E2 of the tube from installing a cover plug under the mistaken assumption that the end E2 should not be open, or from trying to mistakenly try to connect the open tube to some other port.

Providing the reservoir <NUM> configured to hold a volume of the mixed air and oxygen gas has substantial benefits. It allows the flow rate of the supplied air and oxygen gas to be reduced, because at times when "extra" gas is needed, such as during inhalation, mixed air and oxygen gas can be drawn in from the reservoir <NUM>; whereas, when "too much" gas is being supplied by the mixer <NUM> (such as during exhalation), the excess air and oxygen gas flow replenishes the reservoir <NUM>. The benefit of minimizing wall gas usage is that, under COVID-<NUM> pandemic conditions (or other pandemic conditions), oxygen usage is known to be compromised in some medical facilities because of high oxygen usage through the medical facility. Furthermore, by having the reservoir <NUM> connected with the flow path <NUM>, <NUM> of the mixed air and oxygen gas to the atmospheric inlet <NUM> of the mechanical ventilator <NUM>, and further having the reservoir is open to atmosphere, the pressure inside the reservoir is naturally maintained at about atmospheric pressure. Any excess flow of mixed air and oxygen gas to the reservoir is vented to atmosphere via the port PA. Any excess draw of mixed air and oxygen gas from the reservoir <NUM> can be accommodated by drawing air into the reservoir via the port PA. However, this latter situation may be slightly disadvantageous as it can dilute the oxygen concentration of the volume of the mixed air and oxygen contained in the reservoir <NUM>. Nonetheless, such dilution will be negligibly small if the reservoir has sufficient capacity, as described later herein.

The operation is diagrammatically indicated in <FIG> by way of diagrammatically indicated flow arrows <NUM>, <NUM>. The mixer <NUM> supplies the mixed air and oxygen gas which flows into the special fitting <NUM>, as indicated by the horizontal arrowhead of flow arrow <NUM>. Any excess flow of mixed air and oxygen gas from the mixer <NUM> flows into the reservoir <NUM> as indicated by the downward arrowhead of flow arrow <NUM> and by the leftward arrowhead of flow arrow <NUM>. Such excess typically occurs during exhalation. On the other hand, if the flow from the mixer <NUM> is insufficient to supply the patient (this is typically during inhalation), then mixed air and oxygen gas is supplied by the reservoir <NUM>, as indicated by the rightward arrowhead of flow arrow <NUM> and the horizontal arrowhead of flow arrow <NUM>.

The reservoir <NUM> is configured to hold a volume of the mixed air and oxygen gas that is greater than a volume of the flow path <NUM>, <NUM> of the mixed air and oxygen gas to the atmospheric inlet <NUM> of the mechanical ventilator <NUM>. For example, in some non-limiting embodiments suitable for use with the Philips/Respironics Trilogy EVO mechanical ventilator, the volume of the mixed air and oxygen gas held by the reservoir <NUM> is <NUM> (or less), while the volume of the mixed air and oxygen gas in the flow path <NUM>, <NUM> can be, for example, <NUM>. By allowing the reservoir <NUM> to vent to the atmosphere via port PA and holding a volume of mixed air and oxygen gas that is greater than the volume in the flow path <NUM>, <NUM>, the reservoir <NUM> can control the flow of the mixed air and oxygen gas to the mechanical ventilator <NUM>. As such, in some non-limiting embodiments, the gas delivery apparatus <NUM> is not configured to receive any control signal from the mechanical ventilator <NUM>. This is because no such control signal is needed to control operation of the gas delivery apparatus <NUM>, as the reservoir <NUM> open to air provides passive regulation of the flow to the atmospheric inlet <NUM>.

The gas delivery apparatus <NUM> also includes the aforementioned special fitting <NUM> configured to connect the connecting device <NUM> (and more particularly port P3 of the branch connector <NUM>) with the atmospheric inlet <NUM> of the mechanical ventilator <NUM>. As previously mentioned, typically the mechanical ventilator <NUM> is designed to draw atmospheric air in via the atmospheric inlet <NUM>. As such, there is usually no need to connect a gas supply to the atmospheric inlet <NUM>. However, the atmospheric inlet <NUM> may include threading or other connection hardware for attaching a dust filter or the like, and this may be leveraged to simplify the construction of the special fitting <NUM>.

With reference to <FIG>, and with continuing reference to <FIG>, <FIG>, and <FIG>, the fitting <NUM> includes an inlet <NUM> that connects with port P3 of the Y-connector <NUM>, and an outlet <NUM> configured to make a sealed connection with the atmospheric inlet <NUM> of the mechanical ventilator <NUM>. The outlet <NUM> of the fitting is configured to make sealed connection with the atmospheric inlet <NUM> of the mechanical ventilator <NUM>.

The gas delivery apparatus <NUM> is, in some non-limiting embodiments, configured for use with a plurality of different mechanical ventilators <NUM> having different respective atmospheric inlets <NUM> for drawing in atmospheric gas. To do so, a ventilator retrofit package includes a plurality (or set) of specialized fittings corresponding to various different atmospheric inlets of different mechanical ventilators <NUM>. Each specialized fitting <NUM> has the same inlet <NUM> but has its outlet <NUM> configured to make sealed connection with the atmospheric inlet <NUM> of the corresponding mechanical ventilator <NUM>. This allows the same connecting device <NUM> to be used to deliver controlled oxygen to any make or model of mechanical ventilator for which a suitable specialized fitting is included in the set of specialized fittings of the retrofit package. In a medical crisis situation such as an outbreak of a highly contagious respiratory disease in which many patients may need to be ventilated with supplemental oxygen, this provides substantial flexibility to medical personnel in leveraging existing mechanical ventilators to deliver controlled oxygen, even with mechanical ventilators such as CPAP or BiPAP devices that are not conventionally capable of providing oxygen therapy.

As best shown in <FIG>, an example of the fitting <NUM> for use with, for example, Philips/Respironics Trilogy EVO mechanical ventilator <NUM> is shown. As shown in <FIG>, the fitting <NUM> that would allow the "Y" connector <NUM> of the dual-limb circuit (here "dual limb circuit" refers to the two limbs attached to ports P1 and P2 of the branch connector <NUM> and not to a dual-limbed patient circuit) to be connected to the inlet <NUM> of the mechanical ventilator <NUM> with a seal so that no atmospheric air can leak into the ventilator. Such a fitting <NUM> could be adapted for each ventilator <NUM> that uses this blended oxygen approach. For the Trilogy EVO adaptor fitting <NUM>, an existing CBRN filter adaptor (e.g., a part labeled <NUM>) may be used in conjunction with the fitting <NUM>. In some examples, a length of tubing (not shown) can be added to connect the port P3 of the Y-connector <NUM> with the fitting <NUM>. In other examples, the fitting <NUM> can comprise a flexible or sealable coupling capable of being universally or semi-universally connect with the mechanical ventilator <NUM> instead of being designed for a given vent (i.e., the atmospheric inlet <NUM>).

The fitting <NUM> can be machined and/or molded to meet commercialization demands. The fitting <NUM> in this example provides a standard <NUM> ISO connection to interface with this proposed O<NUM> blending solution while interfacing to the mechanical ventilator <NUM> with a NATO standard thread. The fitting <NUM> may, for example, be machined aluminum, cleaned for O<NUM> use and clear anodized. Alternatively, the fitting <NUM> may be injection-molded and produced from a myriad of different thermoplastics.

With reference to <FIG>, and with continuing references to <FIG>, <FIG>, <FIG>, and <FIG>, a mechanical ventilation method <NUM> performed by the gas delivery apparatus <NUM> is shown. At an operation <NUM>, air from the air supply <NUM> and oxygen gas from the oxygen supply <NUM> are mixed with mixer <NUM> to generate a volume of mixed air and gas. At an operation <NUM>, the mixed air and oxygen gas are flowed by the tube <NUM> from the mixer <NUM> to the atmospheric inlet <NUM> of the mechanical ventilator <NUM>.

At an operation <NUM>, the flow of the mixed air and oxygen gas is buffered using the reservoir <NUM>. In one example, the buffering operation <NUM> can include venting the opening PA of the reservoir <NUM> to atmosphere. In another example, the buffering operation <NUM> includes providing the tube <NUM>-<NUM> with a first end E1 in fluid connection with the flowing mixed air and oxygen gas and a second end E2 that is open to atmosphere.

At an operation <NUM>, a flow rate of the mixer <NUM> is adjusted to control a fraction of oxygen (e.g., FiO<NUM>) in the mixed air and oxygen gas using the user control <NUM>. For example, the flow rate of the mixer <NUM> can be adjusted to be set to an average leak of the mechanical ventilator <NUM> according to V̇ventilator = V̇Tventilator × Ψ, in which V̇ventilator is a minute rate of the mechanical ventilator <NUM>, VTventilator is a volume delivered by the mechanical ventilator, and Ψ is a patient breath rate. This calculation can be performed by the processor <NUM> of the mechanical ventilator <NUM>, and can be output to the medical professional via the display <NUM> of the mechanical ventilator. However, this is merely an illustrative example. In another contemplated embodiment, if the mechanical ventilator <NUM> measures the fractional oxygen (FiO<NUM>) and reports that on the display <NUM>, then the clinician can merely adjust the user control <NUM> to set the FiO<NUM> to the desired value. If the ventilator does not report FiO<NUM> then a dedicated FiO<NUM> monitor (not shown) could be used to measure the FiO<NUM> value. Again, these are illustrative examples.

The disclosed gas delivery apparatus including the connecting device <NUM> and special fitting <NUM> can be deployed with substantially any type of mechanical ventilator. It may be used with either a single-limbed patient circuit or a dual-limbed patient circuit.

Claim 1:
A gas delivery apparatus configured for use with a mechanical ventilator (<NUM>) having an atmospheric inlet (<NUM>) for drawing in atmospheric gas, the gas delivery apparatus comprising:
a connecting device (<NUM>) configured to connect to an oxygen supply (<NUM>) and an air supply (<NUM>) and to deliver mixed air and oxygen gas to the atmospheric inlet of the mechanical ventilator, the connecting device further including a user control (<NUM>) for adjusting a fraction of oxygen in the mixed air and oxygen gas;
wherein the connecting device comprises a reservoir (<NUM>) configured to hold a volume of the mixed air and oxygen gas; and
wherein the reservoir (<NUM>) is connected with a flow path (<NUM>, <NUM>) of the mixed air and oxygen gas to the atmospheric inlet (<NUM>) of the mechanical ventilator (<NUM>), and the reservoir is open to atmosphere.