Patent Description:
Respiratory treatment apparatus can function to supply a patient with a supply of clean breathable gas (usually air, with or without supplemental oxygen) at a therapeutic pressure or pressures, at appropriate times during the subject's breathing cycle. Pressure changes may be implemented in a synchronized fashion so as to permit greater pressures during inspiration and lower pressures during expiration. Therapeutic pressure is also known as the ventilation pressure.

Respiratory treatment apparatus typically include a flow generator, an air filter, a mask, an air delivery conduit connecting the flow generator to the mask, various sensors and a microprocessor-based controller. Optionally, in lieu of a mask, a tracheotomy tube may also serve as a patient interface. The flow generator may include a servo-controlled motor, volute and an impeller that forms a blower. In some cases a brake for the motor may be implemented to more rapidly reduce the speed of the blower so as to overcome the inertia of the motor and impeller. The braking can permit the blower to more rapidly achieve a lower pressure condition in time for synchronization with expiration despite the inertia. In some cases the flow generator may also include a valve capable of discharging generated air to atmosphere as a means for altering the pressure delivered to the patient as an alternative to motor speed control. The sensors measure, amongst other things, motor speed, mass flow rate and outlet pressure, such as with a pressure transducer or the like. The apparatus may optionally include a humidifier and/or heater elements in the path of the air delivery circuit. The controller may include data storage capacity with or without integrated data retrieval and display functions.

These devices may be used for the treatment of many conditions, for example respiratory insufficiency or failure due to lung, neuromuscular or musculoskeletal disease and diseases of respiratory control. They may also be used for conditions related to sleep disordered breathing (SDB) (including mild obstructive sleep apnea (OSA)), allergy induced upper airway obstruction or early viral infection of the upper airway.

It may be desirable to develop further methods and devices for controlling the flow of breathable gas in a respiratory treatment apparatus during operations. <CIT> proposes an apparatus for assisting with ventilating a patient breathing in successive cycles, each of which comprises a phase of inhalation and a phase of exhalation, of the type comprising: a pressurized gas source, an outlet orifice of which supplies a stream of pressurized gas; a gas stream distribution unit which comprises a transmission circuit which connects the gas source to a main inhalation pipe; and an inhalation valve for regulating the said gas stream and which is interposed in the transmission circuit and is controlled by a control circuit of the apparatus particularly as a function of the values of the flow rate and of the pressure of the gas in the main pipe, characterized in that the inhalation valve is produced in the form of a rotary directional-control valve.

An aspect of some embodiments of the current technology is to provide a flow control device for a respiratory treatment apparatus.

Another aspect of some embodiments of the technology is to provide a variable inlet for a respiratory treatment apparatus.

A still further aspect of some embodiments of the technology is to provide an inlet flow control device that is adjustable in accordance with patient flow.

A yet further feature of some embodiments of the technology is to provide a flow control device to prevent back flow.

A still further aspect of some embodiments of the technology is to provide such a flow control device to prevent a back flow or return of breathable gas in a respiratory treatment apparatus based on detected conditions.

Another aspect of some embodiments of the technology is to provide a flow control seal for an inlet of a flow generator.

For example, in some embodiments of the technology, a respiratory treatment apparatus may be configured to provide a flow of breathable gas to a patient. The apparatus may include a gas inlet having a variable aperture that is adjustable between closed and fully open and a gas outlet. A flow generator of the apparatus may be adapted to provide a supply of pressurized breathable gas from the gas inlet and to the gas outlet. The apparatus may also include a controller to control the level of pressure generated by the flow generator. The aperture may vary in opening size as a function of a level of flow of breathable gas provided adjacent to the gas outlet. The variable aperture may include a flexible seal. It may also be configured for proportional opening over a range of flow values where the range of flow is between a first flow value and a second flow value. In some embodiments, the first flow value may be approximately <NUM> liters per minute and the second flow value may be approximately <NUM> liters per minute. Optionally, the variable aperture may be configured at a fixed opening size for flow values above the range of flow. The variable aperture may also be configured to be closed at the first flow value of the range of flow. The variable aperture may also include a seal activation chamber. The pressure of the seal activation chamber may be set by control of one or more electro-mechanical valves. The controller may set the electromechanical valve as a function of a measure of the level of flow of breathable gas. Optionally, the aperture may include an electro-mechanical valve and the controller may be configured to set a size of an opening of the electromechanical valve as a function of a measure of the level of flow of breathable gas.

In some embodiments of the technology, a respiratory treatment apparatus is configured to provide a supply of pressurized breathable gas to a patient in successive respiratory cycles where each cycle includes an inspiration phase and an expiration phase. The apparatus may include a gas inlet, a gas outlet and a flow generator that is adapted to receive an inlet flow of breathable gas from the gas inlet and to pressurize the breathable gas prior to delivery to the gas outlet. A controller of the apparatus may then be adapted to control the level of pressure generated by the flow generator to provide an inspiratory pressure and an expiratory pressure wherein during at least a portion of the expiration phase the inlet flow to the flow generator is interrupted to facilitate the reduction in pressure from the inspiratory pressure to the expiratory pressure. This interruption of the inlet flow may then unload a blower of the flow generator. In some such embodiments, the controller may be configured to interrupt the inlet flow by setting one or more electro-mechanical valves. For example, the apparatus may include a flexible seal in a flow path of the inlet and a seal activation chamber proximate to the flexible seal. The setting of the electro-mechanical valve may then control a pressure level of the seal activation chamber.

In some embodiments of the present technology, a flow generator for a respiratory treatment apparatus includes a motor, a volute and an impeller coupled with the motor. A housing for the impeller has a gas inlet and a gas outlet. The gas outlet is adaptable for a conduit of a patient interface to deliver breathable gas as a respiratory treatment. The apparatus also includes an inlet flow seal positioned to selectively open and close the gas inlet. The inlet flow seal has a first side internally proximate to an inlet chamber of the gas inlet and the inlet flow seal has a second side externally proximate to the inlet chamber of the gas inlet. The seal activation chamber is configured proximate to the second side of the inlet flow seal to permit a negative pressure in the seal activation chamber to open the gas inlet to a flow of breathable gas.

In some embodiments, the housing also includes first and second ports and a pressure communication conduit to connect a posterior portion of the inlet chamber and the seal activation chamber for pressure communication such that a negative pressure in the inlet chamber results in a negative pressure in the seal activation chamber. Optionally, the flow generator may also include a first flow control valve coupled with the pressure communication conduit. The first flow control valve may be configured to selectively switch the seal activation chamber to the pressure in the pressure communication conduit associated with the inlet chamber pressure or to atmospheric pressure.

In some embodiments, the negative pressure in the seal activation chamber is due to the flow of breathable gas flowing towards the gas outlet. Moreover, this flow can be controlled by a breathing cycle. Thus, configuration of the seal activation chamber and the setting of the flow control valve may allow flow to a patient from the inlet through the flow generator and to the outlet.

Optionally, the negative pressure in the seal activation chamber may be discontinued when the flow control valve is set to open to atmospheric pressure resulting in a substantial ambient pressure equalization in the seal activation chamber. This equalization may then permit closure of the gas inlet to a flow of breathable gas such as the flow from the inlet through the flow generator and to the outlet.

Back flow through the gas inlet may also be prevented when the device is set to permit equalization between the seal activation chamber and the gas inlet chamber. The back flow from the gas outlet to the gas inlet increases pressure in the inlet chamber and the seal activation chamber such that the increase in pressure permits closure of the gas inlet with the seal.

In still further embodiments, a second flow control valve is coupled with the first flow control valve. The second flow control valve may be configured to selectively switch the gas inlet of the first flow control valve to pressure of the gas outlet or ambient pressure. The switch to ambient pressure may be provided directly to ambient or to the anterior portion of the inlet chamber which can be substantially equivalent to ambient pressure.

In some embodiments, the flow control device may be selectively set to permit back flow. For example, the apparatus may set one or more control valves to seal a desired pressure level within the seal activation chamber such that the seal activation chamber discontinues equalizing with a pressure of the gas inlet chamber and an ambient pressure. The sealed pressure level therein, which may be a negative pressure, can lock the inlet flow seal in an open position even when the pressure of the inlet chamber increases due to the back flow.

Optionally, a controller of the flow generator may be configured to set the first flow control valve to permit a negative pressure in the seal activation chamber to open the gas inlet to a flow of breathable gas in response to a detection of a condition of inspiration. The controller may also be configured to set the first and optionally the second flow control valves to discontinue the negative pressure in the seal activation chamber to close the gas inlet to a flow of breathable gas in response to a detection of a condition of expiration.

The technology may also be implemented as a respiratory treatment apparatus that includes a flow generator to produce a breathable gas at a pressure above atmospheric pressure for a pressure therapy regime. The flow generator may include a gas inlet and a gas outlet where the gas outlet is adaptable for a conduit of a patient interface to deliver the breathable gas. The apparatus may also include a controller to control the flow generator to produce the breathable gas according to a pressure therapy regime. An inlet flow seal of the apparatus may be positioned to selectively open and close the gas inlet where the inlet flow seal has a first side internally proximate to an inlet chamber of the gas inlet and a second side externally proximate to the inlet chamber of the gas inlet. The apparatus may also include a seal activation chamber proximate to the second side of the inlet flow seal wherein a negative pressure in the seal activation chamber permits opening of the gas inlet to a flow of breathable gas.

In some embodiments of the apparatus, a pressure communication conduit connects the interior inlet chamber and the seal activation chamber for pressure communication such that a change in pressure in the interior inlet chamber changes the pressure in the seal activation chamber. In still further embodiments of the apparatus, a first flow control valve is coupled with the seal activation chamber and is configured to selectively switch between the pressure communication conduit and atmospheric pressure under control of the controller. In some further embodiments a second flow control valve of the apparatus may be coupled with the first control valve and be configured to selectively switch between (a) equalizing pressure (permitting flow) between the gas inlet and the gas outlet and (b) equalizing pressure (permitting flow) between the gas inlet and the first control valve. In such a case, the pressure at the gas inlet may be substantially ambient pressure.

The flow generator of the apparatus may include a motor, volute and an impeller configured between the gas inlet and the gas outlet. Similar to previously described embodiments, one or more of the valves may be set to control the pressure in the chamber and the seal so as to permit flow, stop flow, prevent back flow and permit back flow.

In some embodiments of the technology, a system regulates flow to a flow generator in a respiratory treatment apparatus. The system may include a gas inlet to a flow generator through which a flow of breathable gas is drawn. The system may also include means for sealing off the flow at the gas inlet. The means for sealing may have a first side internally proximate to an inlet chamber of the gas inlet and a second side externally proximate to the inlet chamber of the gas inlet. The system may also include a chamber means that is proximate to the second side of the means for sealing wherein a negative pressure therein opens the gas inlet at the means for sealing. The system may also include a means for changing pressure to the chamber means in accordance with a change in pressure in the gas inlet. Still further, the system may include means for selectively discontinuing the change in pressure in the chamber means while permitting the change in pressure in the gas inlet.

Optionally, the aforementioned embodiments may also include an oxygen input port coupled to the inlet to inject oxygen gas into the gas inlet.

Additional features of the present respiratory treatment apparatus technology will be apparent from a review of the following detailed discussion, drawings and claims.

The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference numerals refer to similar elements including:.

Example embodiments of the current invention may be implemented with a breathable gas inlet control device <NUM> for a flow generator or a respiratory treatment apparatus including components illustrated in the schematic diagram of <FIG>. Typically, the flow generator, such as a servo-controller blower <NUM>, will include a motor, volute and impeller <NUM>. With the impeller <NUM>, the blower can produce a flow of breathable gas (e.g., air) to the gas outlet <NUM>. Although <FIG> illustrates a flow generator of the blower type, also known as a radial compressor, other flow generators may be utilized such as a piston based compressor. In a respiratory treatment apparatus, the gas outlet <NUM> will typically be configured for coupling with a patient interface for respiratory treatment such as a delivery or supply conduit and mask or tracheotomy tube (not shown).

The breathable gas can be drawn into the blower through a gas inlet <NUM> by powered rotation of the impeller. Rotation of the impeller <NUM> creates a lower gas pressure condition at the inlet and a higher gas pressure condition at the outlet relative to ambient or atmospheric pressure. The gas inlet can be formed by an inlet chamber <NUM> that serves as a path that directs a flow of gas drawn into the impeller <NUM>. As shown in <FIG>, an aperture <NUM> of the inlet chamber <NUM> may be sealed by an inlet flow seal <NUM>. Controlled movement of the inlet flow seal <NUM> serves to impede flow by preventing or permitting gas transfer between an anterior portion 110A of the gas inlet chamber <NUM> exterior of the seal and a posterior portion 110P of the gas inlet <NUM> interior of the seal.

As illustrated in <FIG>, the inlet flow seal <NUM> is coupled to a cavity or seal activation chamber <NUM>. Selective control of the gas pressure within the seal activation chamber serves to control the movement of the inlet flow seal <NUM>. For example, the inlet flow seal <NUM> may be formed by a flexible membrane. The membrane may be formed and positioned to permit it to resiliently close or seal the aperture <NUM> under a normal pressure condition such as when an ambient pressure condition exists within the seal activation chamber <NUM> and in the gas inlet <NUM>. As illustrated in the embodiment of <FIG>, such a pressure condition may exist when the blower <NUM> is not operating. Moreover, depending on the resilience of the seal and/or the pressure condition in the seal activation chamber, the seal can prevent a back flow of gas from the posterior portion 110P of the inlet chamber <NUM> toward the anterior portion 110A of the inlet chamber <NUM>. Thus, the inlet flow seal may also operate as a non-return valve.

The cross-sectional area of the inlet flow seal <NUM> (i.e. , the surface area of the seal) may be designed to be larger than the cross-sectional area of the gas passageway of the inlet aperture <NUM> as illustrated in <FIG> Consequently, the cross-sectional area ratio of the aperture to the inlet flow seal can be greater than <NUM>:<NUM>, preferably between about <NUM>:<NUM> and about <NUM>:<NUM>, more preferably the ratio is about <NUM>:<NUM>. In the example of <FIG>, the surface area <NUM> of the seal <NUM> is about two times the cross-sectional area <NUM> of the gas passageway, <NUM> of the inlet aperture (i.e., area ratio AR<NUM>/AR<NUM> = <NUM>/<NUM>).

In the embodiment of <FIG>, a flow control valve <NUM>, such as an electro-mechanical valve (e.g., a three port, two way valve), may be implemented to permit changes to the pressurization of the seal activation chamber <NUM>. For example, as illustrated, the flow control valve <NUM> may be selectively set to permit the pressure of the seal activation chamber <NUM> to equalize with different pressures such as with an ambient pressure (illustrated in <FIG> as arrow "AP") through a first conduit <NUM> or another pressure of the inlet chamber <NUM> through a second conduit or the pressure communication conduit <NUM>, such as the ambient pressure of the posterior portion 110P of the inlet chamber <NUM> when the blower is not operating.

Several operational modes of the apparatus of <FIG> will now be described with reference to <FIG>, <FIG>, <FIG> and <FIG>.

As illustrated in <FIG>, a negative or decreased pressure relative to ambient pressure may exist within the posterior portion 110P of the inlet chamber <NUM>. This negative pressure (illustrated in <FIG> as arrow "DP") may be communicated to the seal activation chamber <NUM> via the pressure communication conduit <NUM> by operation of the flow control valve <NUM>. For example, as further illustrated in <FIG>, when the blower is activated and the flow is directed towards the gas outlet <NUM>, the flow controlvalve <NUM> may be set to permit pressurization of the seal activation chamber <NUM> at the negative pressure "DP" of the inlet chamber <NUM> caused by the pressure of the inwards flow of breathable gas such as when the patient inhales (i.e., inspiration). The pressure may be communicated to the seal activation chamber <NUM> through the pressure communication conduit <NUM> serving as a pneumatic link. Significantly, the seal activation chamber <NUM> and the inlet flow seal <NUM> may be configured to permit opening of the aperture <NUM> as a result of this change in pressure in the seal activation chamber <NUM>. In this regard, the rotation of the impeller of the blower acts as a pressure source but the pressure drop in the posterior portion 110P of the inlet chamber <NUM> relative to the anterior portion 110A that opens the seal is a consequence of flow through the inlet chamber <NUM> rather than simply from the rotation of the impeller. For example, the flow through the posterior portion 110P may be controlled or induced by the breathing cycle of the patient whether or not the blower is powered. Moreover, as illustrated in more detail herein, in some states of the apparatus the blower may be powered (e.g., rotating) but there may be no flow through the posterior portion 110P, such as when the output of the blower is blocked. Nevertheless, if patient flow exists, the impeller-induced pressure in conjunction with the patient's flow-induced pressure may both contribute to the level of pressure that will exist in the posterior portion.

The size of the aperture <NUM> and the seal <NUM> as well as the flexibility of the seal can be chosen so that the decrease in pressure within the chamber retracts one or more portions of the seal into the seal activation chamber <NUM>. This retraction may withdraw the seal <NUM> into the seal activation chamber <NUM> providing a gap between the anterior portion 110A of the inlet chamber <NUM> and the posterior portion 110B of the inlet chamber <NUM>. This retraction of the seal will then permit gas flow between the seal and the aperture from the anterior portion 110A to the posterior portion 110P and then into the impeller.

Depending on the flexibility of the seal, the extent. of the movement of the seal can be a function of the varying flow generated by the patient. Thus, the size of the opening formed by the aperture and the flexible seal during blower operation can be proportional to the induced flow as illustrated by the dotted lines in <FIG>. For example, greater inwards flow in the posterior portion 110P of the inlet chamber can result in greater openings of the aperture <NUM> to allow more flow into the blower. Similarly, smaller inwards flow in the posterior portion 110P of the inlet chamber can result in smaller openings of the aperture <NUM> to allow less flow into the blower. The proportional opening permits the forming of a minimum necessary opening size sufficient to permit the desired flow drawn by the blower. Since larger openings can cause greater noise as the flow of gas passes across the opening, a potential benefit of such a proportional flow opening is a reduction of noise. Such a feature can be significant for a respiratory treatment apparatus designed for treatment of patients during sleep.

Thus, in some embodiments, the inlet control device may be implemented with a variable inlet opening to allow different levels of flow to be supplied during inspiration as required by the patient. During inspiration the seal acts as a passive proportional valve that adjusts its distance from a rim of the aperture <NUM> to implement a variable opening. The size of the opening then may be related to the level of patient flow. In a particular example embodiment, a simple passive pneumatic (flow) servo control may be implemented as follows:.

However, other flow ranges may be configured. When compared to devices that have fixed inlet openings, such a variable opening can optimize the working conditions of the blower and/or decrease the noise radiating from the system.

As further illustrated in <FIG>, when the blower is activated, the flow control valve <NUM> may be set to relieve or discontinue the pressurization of the seal activation chamber <NUM> without necessarily also stopping or reducing the powered impeller rotation. For example, the flow control valve <NUM> may be set to communicate an ambient pressure to the seal activation chamber <NUM> through the first conduit <NUM> or pneumatic link. The resultant equalization in pressure in the seal activation chamber <NUM> can permit the inlet flow seal <NUM> to return to its normal configuration adjacent to the aperture <NUM> and thereby to seal the aperture <NUM>. Moreover, in addition to the seal resilience, in the event that the blower is still operating (i.e., the impeller is still rotating) or the patient still inspiring as shown in <FIG>, the decreased pressure condition in the posterior portion 110P of the inlet chamber <NUM> in relation to the higher ambient pressure condition in either of the anterior portion 110A of the inlet chamber <NUM> or the seal activation chamber <NUM> can further serve as a suction force to further enforce closing of the seal to the aperture <NUM>.

Accordingly, the seal then can serve as an efficient and rapid means to prevent a flow of gas into the blower (i.e., shut off the inlet supply) without necessarily changing the speed of the blower or necessarily relying on braking of the motor of the blower. Avoidance of braking can reduce heat and keep the blower cooler. Avoidance or reduction of braking may also serve to reduce energy requirements of the system since less current may be required to operate the valves of the inlet flow control device when compared to supplying the current to the flow generator to control a reduction in blower speed.

Accordingly, in some example embodiments, the inlet control can be implemented to reduce pressures delivered by the blower during expiration with or without braking of the motor speed. It may also be implemented to more immediately stop and start generating flow from the blower. For example, a rapid stopping and starting of flow can be controlled by a controller using this device to then induce a percussive mode of breathing in a patient that may be suitable for causing secretion removal (e.g., inducing patient coughing).

Thus, the closing of the inlet control device <NUM> may serve as part of a control scheme for making controlled adjustments of the supplied treatment gas. For example, this reduction in size of the inlet aperture (e.g., closing) may be implemented to transition from an inspiration pressure to an expiration pressure without. relying on a rapid deceleration of the blower. In this regard, the blower is unloaded by shutting off the flow (e.g., closing of the inlet control device <NUM>). This means that the blower will decelerate more quickly and will not require the high levels of induced current normally required when braking a blower that is still receiving flow through the inlet. In other words, the blower does not have any load when it cannot draw air in through the inlet. Thus, the flow can be interrupted with a rapid response time due to this unloading of the blower. The ability to rapidly control the flow allows the shape of the respiratory treatment waveform produced by the flow generator to be more finely tuned. If a sharp pressure waveform/response is required then the inlet control device aperture can be closed rapidly.

In some other types of devices lacking the present invention , the transition from inspiration to expiration can result in a flow spike at the beginning of expiration due to the time that is required for the blower to slow down. This flow spike can be avoided in embodiments of the present invention by the closing of the inlet control device and thereby shutting off inlet flow.

Thus, in some embodiments, the controller may detect an expiratory related condition (e.g., beginning of expiration, end of inspiration, etc.) from the sensors (e.g., a measure from a flow sensor) and set the valves of the inlet control device to close the inlet aperture and thereby interrupt flow to the flow generator. Optionally, the controller may also simultaneously or contemporaneously change a setting (e.g., reduce current) of the flow generator to, for example, reduce a speed of the flow generator to a setting suitable for generating a pressure appropriate for expiration (e.g., an expiratory pressure level). Such a controller change might also involve the setting of a flow generator used for generating a positive end expiratory pressure level (PEEP). Thus, the control of the inlet flow device, and optionally the flow generator, can also assist in implementing a desired shape of a generated respiratory treatment pressure waveform.

As illustrated in <FIG>, the blower may be activated while the flow control valve <NUM> may be set to equalize the pressure of the seal activation chamber <NUM> and the posterior portion 110P of the inlet chamber <NUM>. Moreover, the output of the blower at or beyond the outlet <NUM> may be blocked (e.g., due to some problem of the patient interface or if the patient is neither inhaling nor exhaling) so as to prevent blower induced flow out of the outlet <NUM>. During this operation, without patient flow, the seal <NUM> can remain in a position to close the aperture <NUM> due to the configuration of the seal and the equalized pressure of the seal activation chamber <NUM> and the posterior portion 110P of the inlet chamber <NUM>, which will be approximately the same pressure as the anterior portion <NUM> of the inlet chamber <NUM>.

Shutting off the flow also results in other benefits such as when it is implemented to prevent back flow with a non-vented mask system. For example, as illustrated in <FIG>, the blower may be activated while the flow control valve <NUM> may be set to equalize the pressure of the seal activation chamber <NUM> and the posterior portion 110P of the inlet chamber <NUM>. In such a condition, a patient might expire so as to induce a back flow BF condition into the outlet <NUM> and thereby create a positive pressure (shown as "HP" in <FIG>), relative to ambient, in the posterior portion 110P of the inlet chamber <NUM>. However, in such a case, the seal <NUM> can remain in a position to close the aperture <NUM> and prevent the back flow due to the configuration of the seal and the equalized pressure of the seal activation chamber <NUM> and the posterior portion 110P of the inlet chamber <NUM>, even though the positive pressure HP of the posterior portion 110P would exceed the ambient pressure in the anterior portion 110A of the inlet chamber <NUM>.

The prevention of back flow can also have benefits for a system that utilizes oxygen. For example, when oxygen is injected after or downstream of the blower as discussed in more detail herein, shutting off the flow during expiration by closing the valve means that the oxygen may be maintained in the pressure side of the device (e.g., no oxygen escapes outside the device). Also this arrangement may reduce the exposure of the motor to oxygen as there is no or minimal oxygen backflow through the blower.

Components of an example inlet control assembly are illustrated in <FIG>. The inlet flow seal <NUM> is formed of a flexible material with a sealing surface <NUM>. The sealing surface <NUM> serves as a membrane for plying against an inlet aperture (not shown) as previously described. A clamp ring <NUM> having flexible prongs <NUM> is configured for clamping the outer perimeter lip <NUM> of the inlet flow seal <NUM> to a chamber body <NUM> to form the seal activation chamber <NUM> between the chamber body and the inlet flow seal. The chamber body <NUM> includes holes <NUM> to permit inlet airflow through the chamber body <NUM> around and externally of the seal activation chamber <NUM>. Some of the holes may also be spaced and sized to receive the flexible prongs <NUM> of the clamp ring <NUM> when the prongs are snapped or engaged with the holes. The chamber body <NUM> includes a pressure port <NUM> for communicating the selected pressure from one or more flow control valves <NUM> (not shown in <FIG>).

<FIG> contains a cross sectional illustration of the example inlet control assembly components coupled to a blower <NUM> or flow generator. The illustrated blower <NUM> includes the motor <NUM> and impeller <NUM> coupled to a volute <NUM> that serves as a housing for the impeller <NUM> of the flow generator. In this embodiment, the volute includes the flow inlet <NUM>. When installed, the sealing surface <NUM> of the inlet flow seal <NUM> plies against the circumference of a rim of the flow inlet <NUM>. During the operations previously discussed, the rim of the inlet <NUM> and the retraction of the sealing surface <NUM> forms an opening at the aperture <NUM>. In this embodiment, the wall of the volute that serves as the inlet <NUM> includes a pressure port <NUM>. The pressure port <NUM> of the inlet <NUM> permits an exchange of pressure between the posterior portion of the inlet chamber 110P and the seal activation chamber <NUM> through a conduit (not shown in <FIG>) and the flow control valve <NUM> (also not shown in <FIG>).

As illustrated in <FIG>, the particular structure of this embodiment may have the potential for miniaturization. That is, its compact design can reduce the size of the housing of a respiratory treatment apparatus. In this regard, the location of the seal and seal activation chamber at the inlet and close to the blower can provide a reduction in space. In this regard, portions of the components of the inlet control device may be integrated with a volute for the blower. However, it is also possible in alternative embodiments to locate the seal activation chamber and seal elsewhere with respect to the apparatus or blower. For example, it may be attachable and/or removable to the blower or blower housing via a tube or other conduit (not shown).

Another embodiment of the inlet control assembly is illustrated in <FIG>. In this embodiment, the inlet flow seal <NUM> is clamped between mounting ring <NUM> and chamber body <NUM>. The mounting ring <NUM> is adapted for removable installation with the wall of the inlet chamber <NUM>. For example, side clips of threads (not shown) of the mounting ring <NUM> may mate with receiving grooves (not shown) of the wall of the inlet chamber <NUM>. When snapped or rotated in place, the mounting ring secures the inlet control assembly to the blower volute <NUM>. In this example of the inlet control assembly, the mounting ring <NUM> includes flexible prongs <NUM> configured for clamping the outer perimeter lip <NUM> of the inlet flow seal <NUM> to the chamber body <NUM> to form the seal activation chamber <NUM> between the chamber body arid the inlet flow seal. The chamber body <NUM> includes holes <NUM> to permit inlet airflow through the chamber body <NUM> around and externally of the seal activation chamber <NUM>. Some of the holes may also be spaced and sized to receive the flexible prongs <NUM> of the mounting ring <NUM> when the prongs are snapped or engaged with the holes. The chamber body <NUM> includes the pressure port <NUM> for communicating the selected pressure from one or more flow control valves <NUM> (not shown in <FIG>). Another pressure port <NUM> leading to the posterior portion 110P of the inlet chamber <NUM> is integrated into the volute at the wall of the inlet chamber.

In the embodiments of <FIG> and <FIG> various arrangements are shown for coupling components of the inlet control to the housing of a blower or the inlet of a blower. However, additional configurations may also be implemented to achieve a connection with a blower. For example, some or all of the inlet control components may be configured as a removable unit or module. The unit or module may then be removably coupled to a portion of an inlet of a blower or housing thereof. For example, the unit or module may be configured with a bayonet connection or a bayonet coupler. Similarly, the unit or module may be coupled to the inlet of a blower such that it mates with the inlet of the blower by an interference fit. Other coupling arrangements may also be implemented such as a snap-fit arrangement.

As previously discussed, the breathable gas inlet control <NUM> device may be implemented with the flow generator of a respiratory treatment apparatus <NUM>, such as the ventilator or continuous positive airway pressure device illustrated in <FIG>. Such an apparatus includes a controller <NUM>, with one or more microcontrollers or processors, so that the respiratory treatment apparatus <NUM> may be configured with one more treatment regimes for setting the pressure delivered by the pressure generator or blower in conjunction with signals from optional pressure sensors(s) and/or flow sensor(s). Thus, the controller may adjust the speed of the blower during patient treatment to treat detected conditions (e.g., flow limitation, inadequate ventilation, apnea, etc.) and/or synchronize pressure changes during detected patient respiration to simulate or support respiration. In addition, the controller <NUM> may be configured to selectively set the pressure of the seal activation chamber <NUM> by control of one or more flow control valves <NUM> and thereby serve as an inlet flow controller <NUM> for permitting flow of gas (e.g., air or oxygen and air) to the blower and/or to prevent a back flow of gas from the blower. In this manner, the inlet flow controller <NUM> controls the inlet flow seal <NUM>.

Thus, the controller <NUM> or inlet flow controller <NUM> will typically include one or more processors configured to implement particular control methodologies such as the algorithms described in more detail herein. To this end, the controller may include integrated chips, a memory and/or other control instruction, data or information storage medium. For example, programmed instructions encompassing such a control methodology may be coded on integrated chips in the memory of the device. Such instructions may also or alternatively be loaded as software or firmware using an appropriate data storage medium. The controller will also typically include a bus or electronic interface for setting the flow control valves as well as the other components of the apparatus (e.g., blower motor).

During operation of the respiratory treatment apparatus and depending on the desired usage, the inlet flow controller <NUM> may set the gas inlet control device <NUM> based on the detection of different conditions of the system. For example, from an analysis of pressure and flow data, the controller may set the gas control device <NUM> based on the detection of different states of the patient's respiratory cycle or enforcing those states such as inspiration, expiration, start of inspiration, start of expiration, inspiratory peak flow, inspiratory pause, etc. Known methods for the detection of these conditions from pressure and/or flow data or for enforcing them (e.g. timed backup breathing rates) may be implemented by the programming or the circuits of the controller. Various examples of the setting of the gas inlet control device <NUM> by a controller in different system configurations and respiratory states are illustrated in <FIG>.

In the respiratory apparatus configuration of <FIG> an additional flow control valve <NUM> (or pressure relief valve) is added under the control of the inlet flow controller <NUM>. The additional flow control valve <NUM> selectively permits (a) an equalization of pressure or flow between the outlet <NUM> of the blower <NUM> and the anterior portion 110A of the inlet chamber <NUM> through back flow conduit <NUM> or (b) an equalization of pressure or flow between first conduit <NUM> to the first control valve <NUM> and the anterior portion 110A of the inlet chamber <NUM>. However, in some embodiments, the optional back flow conduit <NUM> may not be present. In such a case, the port of the flow control valve <NUM> for the optional back flow conduit <NUM> may be capped such that the flow control valve <NUM> serves only as a <NUM>-way valve able to selectively conduct gas between the inlet <NUM> and the first conduit <NUM>. Optionally, the flow control valve <NUM> may be replaced by a <NUM>-way valve.

In the example of <FIG>, the flow control valve <NUM> can be implemented with a normal state that permits equalization of pressure or permits flow between the outlet <NUM> of the blower <NUM> and the anterior portion 110A of the inlet chamber <NUM>. Such a recirculation of flow from the outlet of the blower <NUM> to the anterior portion 110A of the inlet chamber <NUM> may assist with cooling of the motor and may provide better control of the valve at low flows. Upon activation by the controller <NUM>, the flow control valve <NUM> may then be switched to equalize pressure or permit flow between first control valve <NUM> via first conduit <NUM> and the anterior portion 110A of the inlet chamber <NUM>. Similarly, the flow control valve <NUM> may be implemented with a normal state that permits equalization of pressure or permits flow between the posterior portion 110P of the inlet chamber <NUM> and the seal activation chamber <NUM>. Upon activation by the controller <NUM>, the flow control valve <NUM> may then be switched to equalize pressure or permit flow between the first conduit <NUM> and the seal activation chamber <NUM>. In this case, the pressure of the seal activation chamber <NUM> is further dependent on the setting of the flow control valve <NUM>. For example, when the flow control valve <NUM> is in its activated state and the flow control valve <NUM> is in its normal state, the seal activation chamber <NUM> will effectively be sealed at the last pressure previously applied. Such a case may permit the seal activation chamber <NUM> to "lock" the inlet flow seal <NUM> open if a negative pressure condition existed in the seal activation chamber <NUM> prior to the activation of the flow control valve <NUM>. In such a case, the inlet flow seal may be open even upon deactivation of the blower.

Additionally, in the example system of <FIG>, a second blower or positive end expiratory pressure (PEEP) blower <NUM> may also be included to deliver a positive pressure at the end of patient expiration. Although it is illustrated, the full operations of the PEEP blower <NUM> are beyond the scope of the explanation of the gas inlet control device <NUM> of the present invention. Also shown in the diagram is a safety valve <NUM> in a muffler chamber <NUM>. Generally, the safety valve will be open during patient inspiration and closed during patient expiration.

Operations will now be described with reference to <FIG>. Generally, <FIG> illustrate operations for vented ventilation (i.e., use of the apparatus with a vented patient interface or mask) to the extent that these figures may show an active or powered controller (i.e., turned on). <FIG> is a block diagram illustrating the default setting of the gas inlet control device <NUM> when the respiratory treatment apparatus is off the default setting shown in <FIG> is the same whether a vented or non-vented mask is utilized. In this state the flow control valve <NUM> and flow control valve <NUM> are not active (i.e., they are in their normal states).

<FIG> also illustrates the settings of the gas inlet control device <NUM> when the controller <NUM> implements a ventilation pause such as when the controller detects that the patient's expiration is complete and inspiration has not yet started. Thus, there is no or very low flow. The controller <NUM> does not activate either flow control valve <NUM> or flow control valve <NUM>. While the blower may or may not be powered and it may be rotating in either case, the gas inlet control device <NUM> could be closed so as to prevent back flow from the blower to the anterior portion 110A of the inlet chamber <NUM>.

<FIG> is a block diagram illustrating the setting of the gas inlet control device <NUM> when the respiratory treatment apparatus is on and the controller <NUM> implements the start of inspiration by either detection of patient inspiration or initiation of a timed backup. The controller <NUM> does not activate either flow control valve <NUM> or flow control valve <NUM>. Since in this condition the blower would be powered to deliver an inspiratory positive airway pressure (IPAP), the patient's high inspiratory flow would generate a negative pressure condition or suction in the posterior portion 110P of the inlet chamber and the seal activation chamber <NUM>. Thus, the gas inlet control device <NUM> would be open to permit flow to the blower. Additionally, in this configuration, the flow from the outlet <NUM> through the back flow conduit <NUM> to the inlet chamber can serve a cooling function. With the leak flow created with the back flow conduit, the blower may run at a higher speed. By allowing greater flow through the blower it can serve to cool the blower.

<FIG> is a block diagram illustrating the setting of the gas inlet control device <NUM> when the respiratory treatment apparatus is on and the controller <NUM> detects the expected peak flow of patient inspiration. The controller <NUM> does not activate flow control valve <NUM> but does activate flow control valve <NUM>. In this condition the blower would be powered to deliver an inspiratory positive airway pressure (IPAP). The generated negative pressure condition in the posterior portion 110P of the inlet chamber would then be maintained or sealed in the seal activation chamber <NUM> due to the activation of flow control valve <NUM>. Thus, the gas inlet control device <NUM> would be "locked" open or at least partially open (depending on the amount of patient flow at the time of the activation of flow control valve <NUM>) still permitting flow to the blower.

<FIG> is a block diagram illustrating the setting of the gas inlet control device <NUM> when the respiratory treatment apparatus is on and the controller <NUM> detects patient expiration after the above inspiration. The controller <NUM> does not activate flow control valve <NUM> but does continue to activate flow control valve <NUM>. In this condition the blower would be powered to deliver an expiratory positive airway pressure (EPAP). Since the previously generated negative pressure condition is maintained or sealed in the seal activation chamber <NUM>, the gas inlet control device <NUM> would be "locked" open or partially open. This would permit back flow from the outlet <NUM> through the blower and back out the inlet <NUM> to permit the patient's expiration flow to be vented through the respiratory treatment apparatus.

<FIG> illustrate operations for non-vented ventilation (i.e., use of the apparatus with a non-vented patient interface or mask). In this regard, <FIG> is a block diagram illustrating the setting of the gas inlet control device <NUM> when the respiratory treatment apparatus is on and the controller <NUM> implements the start of inspiration by either detection of patient inspiration or initiation of a timed backup. The controller <NUM> does not activate either flow control valve <NUM> or flow control valve <NUM>. Since in this condition the blower would be powered to deliver a flow or pressure based on a set point of a closed loop control as a result of the patient's inspiratory flow, there would be generated a negative pressure condition in the posterior portion 110P of the inlet chamber and the seal activation chamber <NUM>. Thus, the gas inlet control device <NUM> would be open to permit flow to the blower. Additionally, in this configuration, the flow from the outlet <NUM> through the back flow conduit <NUM> to the inlet chamber can serve a cooling function.

<FIG> is a block diagram illustrating the setting of the gas inlet control device <NUM> when the respiratory treatment apparatus is on and the controller <NUM> detects the start of patient expiration (e.g., by detecting a peak flow threshold). The controller <NUM> activates both flow control valve <NUM> and flow control valve <NUM>. In this condition the controller may de-power the blower. Since the seal activation chamber <NUM> has an ambient condition of the anterior portion 110A of the inlet chamber <NUM> as a result of the flow path through both flow control valve <NUM> and flow control valve <NUM>, the gas inlet control device <NUM> would be closed. The closing of the inlet flow seal and stopping of any inlet flow would then tend to slow the natural inertia of the impeller of the de-powered blower like a brake.

<FIG> is a block diagram illustrating the setting of the gas inlet control device <NUM> when the respiratory treatment apparatus is on and the controller <NUM> detects expiration. Flow-by control may be implemented. Flow-by control is control of the seal during expiration to allow a very low level of flow through the inlet to compensate for leak (e.g., <NUM>-<NUM> litres) at the patient interface. The controller <NUM> does not activate either flow control valve <NUM> or flow control valve <NUM>. In this condition the controller may minimally power the blower for generating a low level of flow based on a flow set point of a flow control loop. Since the seal activation chamber <NUM> has a negative pressure condition from the posterior portion 110P of the inlet chamber <NUM> as a result of the flow path through the flow control valve <NUM>, the gas inlet control device <NUM> would be partially open. The partial opening of the inlet flow seal would then permit a low flow of breathable gas through the blower to the outlet <NUM>.

<FIG> is a block diagram illustrating the setting of the gas inlet control device <NUM> when the respiratory treatment apparatus is on and the controller <NUM> detects an inspiratory pause or plateau. It may also be implemented for an automated positive end expiratory pressure (PEEP) measurement mode. The controller <NUM> activates flow control valve <NUM> but does not activate flow control valve <NUM>. In this condition the blower would be powered at a minimum speed. Due to the absence of patient flow, the gas inlet control device <NUM> would be closed. Moreover, the flow back conduit <NUM> would also be closed as a result of the setting of the flow control valve <NUM>. Thus, flow back into the respiratory treatment apparatus from the patient interface or mask would be prevented.

<FIG> is a block diagram illustrating the setting of the gas inlet control device <NUM> for a failure mode when the respiratory treatment apparatus is on and the controller <NUM> detects that the expiratory valve associated with the venting of the patient interface or mask is blocked, preventing patient exhalation during expiration. Upon detection of this condition, the controller <NUM> activates both flow control valve <NUM> and flow control valve <NUM>. In this condition, equalization of pressure of the seal activation chamber <NUM> and the anterior portion 110A of the inlet chamber <NUM> is permitted. The blower would also be powered to a minimum speed. The patient's expiratory flow would then be sufficient to force open the inlet flow seal <NUM> as a result of the positive pressure created in the posterior portion 110P of the inlet chamber <NUM>. Thus, the gas inlet control device <NUM> would be opened. Thus, flow back into the respiratory treatment apparatus from the patient interface or mask would be permitted.

In some embodiments, a supply of oxygen may also be mixed with the air supply to form the mixed breathable gas at the outlet. The oxygen may be injected in the flow path either downstream or upstream of the blower. For example, in some embodiments, the oxygen may be supplied or injected into the flow path at the outlet <NUM> as indicated by oxygen supply or oxygen inlet port <NUM> in <FIG>. For example, a high flow valve may be implemented to inject the oxygen. Injecting the oxygen after the blower and the valve also assists in preventing the oxygen from escaping back through the system and to atmosphere. This may reduce wastage of oxygen. Furthermore, injecting the oxygen after the blower prevents or limits the exposure of the blower and motor to the flammable oxygen, making the device safer. In alternative versions of the apparatus, the oxygen may be inserted or injected into the inlet <NUM> or inlet chamber <NUM>. This may optionally be injected either in the anterior portion 110A or posterior portion 110P. Thus, the ambient air and oxygen mix then flow through the blower and be pressurized by the blower at the outlet <NUM>. This may be implemented by including a gas input port in the wall of the inlet <NUM>. This option is illustrated in <FIG> as alternative oxygen supply or oxygen inlet port 780A. The oxygen may then be regulated with a valve at the gas input port. For example, the valve may regulate a low flow of oxygen with the ambient air. The apparatus may include oxygen port <NUM> near the outlet or oxygen 780A near the inlet or both oxygen ports <NUM> and 780A to allow a choice of which oxygen port to use. However, generally in use only one of oxygen ports <NUM> or 780A are utilized.

In the foregoing description and in the accompanying drawings, specific terminology, equations and drawing symbols are set forth to provide a thorough understanding of the present technology. In some instances, the terminology and symbols may imply specific details that are not required to practice the technology. Moreover, although the technology herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the technology. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the scope of the technology.

Claim 1:
A flow generator for a respiratory treatment apparatus (<NUM>) comprising:
a motor;
an impeller (<NUM>) coupled with the motor;
a housing for the impeller comprising a volute, a gas inlet (<NUM>) and a gas outlet (<NUM>), the gas inlet (<NUM>) being an inlet to the flow generator, through which a flow of breathable gas is drawn to the flow generator, the gas outlet (<NUM>) being adaptable for a conduit of a patient interface to deliver the breathable gas as a respiratory treatment;
an inlet flow seal (<NUM>) positioned to selectively open and close the gas inlet (<NUM>), the inlet flow seal (<NUM>) having a first side internally proximate to an inlet chamber (<NUM>) of the gas inlet (<NUM>) and the inlet flow seal having a second side externally proximate to the inlet chamber (<NUM>) of the gas inlet (<NUM>); and
a seal activation chamber (<NUM>) configured proximate to the second side of the inlet flow seal (<NUM>) to permit a negative pressure in the seal activation chamber (<NUM>) to open the gas inlet (<NUM>) to a flow of breathable gas.