Patent Application
20070044799
1. Field of the Invention
The invention relates to respiratory treatment systems, and, in particular, to systems that includes a modular assembly that allows the introduction of a supplemental gas, such as oxygen, helium, nitrogen, or any combination there, with a primary flow of gas being delivered to a patient.
2. Description of the Related Art
Ventilators, pressure support systems, and the like (collectively “ventilators”) are commonly used for delivering a pressurized flow of breathable gas to a patient in order to treat a variety of medical conditions, including sleep disordered breathing and the like. Some conventional ventilators are capable of controlling an oxygen concentration level of the gas delivered to the patient by combining supplemental oxygen with the pressurized flow of breathable gas. However, ventilators that provide this functionality are typically expensive.
In an attempt to provide an inexpensive system that elevates the oxygen concentration level of gas delivered to the patient, it is known to introduce a flow of supplemental oxygen into the gas delivered to the patient by the ventilator. Thus, a ventilator without the capability of combining the breathable gas with supplemental oxygen may be used in conjunction with a supply of supplemental oxygen that is introduce into the patient circuit at a location downstream from the ventilator, such as at an entrainment port or at the patient interface, which is the device that attaches the patient circuit to the airway of the patient. While these conventional methods for providing supplemental oxygen to the breathable gas downstream from the ventilator elevate the oxygen concentration level of the breathable gas, they do not enable the oxygen concentration level to be accurately controlled.
Accordingly, it is an object of the present invention to provide a supplemental gas regulator assembly that overcomes the shortcomings of conventional gas delivery techniques. This object is achieved according to one embodiment of the present invention by providing a modular gas regulator assembly that selectively controls a gas concentration delivered to a patient. The a flow of supplemental gas, such as oxygen or heliox (i.e., a helium-oxygen mixture), is delivered to the patient by the modular gas regulator concomitantly with a pressurized flow of breathable gas generated by a gas delivery system, the gas delivery system being controlled by a delivery system processor in the modular regulator.
In an exemplary embodiment, the modular gas regulator assembly comprises a control interface, an gas flow regulator, and a regulator processor. The control interface enables selection of a gas concentration level setpoint. The gas flow regulator regulates a flow rate of the supplemental gas from a gas source. The regulator processor controls the gas flow regulator such that the supplemental gas from the gas source and the pressurized flow of breathable gas delivered to the patient have an gas mixture concentration level that is substantially equal to the gas mixture concentration level setpoint. The regulator processor is independent from the delivery system processor.
Another aspect of the invention relates to a patient treatment system comprising a gas delivery system, a delivery system processor, a modular gas regulator assembly, and a regulator processor. The gas delivery system generates a pressurized flow of breathable gas for delivery to a patient. The delivery system processor is associated with the gas delivery system, and controls the gas delivery system in generating the pressurized flow of breathable gas. The modular gas regulator assembly regulates a flow of supplemental gas, such as oxygen or helium, from a gas source. The supplemental gas is delivered to the patient concomitant with the pressurized flow of breathable gas to selectively control an gas concentration level of the supplemental gas and the pressurized flow of breathable gas delivered to the patient concomitantly. The regulator processor is associated with the modular gas regulator assembly, and regulates the flow of the supplemental gas. The regulator processor is independent from the delivery system processor.
Another aspect of the invention relates to a patient treatment system comprising a first housing, a pressure generator, a first processor, a second housing independent from the first housing, a gas flow regulator, and a second processor. The pressure generator is contained within the first housing, and generates a pressurized flow of breathable gas for delivery to a patient. The first processor is contained within the first housing, and controls the pressure generator. The gas flow regulator is contained in the second housing, and regulates a flow rate of supplemental gas, such as oxygen or heliox, from a supplemental gas supply for delivery to the patient concomitantly with the pressurized flow of breathable gas. The second processor is contained within the second housing, and controls the gas flow regulator.
These and other objects, features, and characteristics of the present invention, 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 the 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. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
Patient treatment system 10 includes a modular oxygen regulator assembly 20 that is implemented as a stand alone device capable of regulating a flow of a supplemental gas, such as oxygen 22, from an oxygen source 24 for delivery to patient 14 concomitantly with the pressurized or primary flow of breathable gas 18 such that the combination of the concomitantly delivered flow of pressurized gas 18 from gas delivery system 16 and supplemental oxygen 22 forms oxygenated gas 12. Oxygen source 24 can be any source of oxygen, such as compressed oxygen from a tank, oxygen provided by an oxygen concentrator or a store of liquid oxygen, or oxygen generated in any manner.
The present invention also contemplates that a separate gas source 28 need not be used, but instead the pressure generator 26 can be defined by a canister or tank of pressurized gas, with the pressure delivered to the patient being controlled by a pressure regulator. In addition, while the embodiment of
In one embodiment of the present invention, pressure generator 26 is a blower that is driven at a constant speed during the course of the pressure support treatment to produce a constant pressure at its output 30.
In the illustrated embodiment, gas delivery system 16 includes a control valve 32. The breathable gas is delivered to control valve 32, with an elevated pressure, downstream of pressure generator 26. Control valve 32, either alone or in combination with pressure generator 26, controls the final pressure or flow of gas 34 exiting the pressure/flow generating system, which, in this embodiment includes pressure generator 26 and control valve 32. Examples of a suitable control valve 32 include at least one valve, such as sleeve or poppet valve, that exhausts gas from the patient circuit as a method of controlling the pressure in the patient circuit. U.S. Pat. No. 5,694,923, the contents of which are incorporated herein by reference, teaches a dual poppet valve system suitable for use as control valve 32 that exhausts gas to atmosphere and restricts the flow of gas from the pressure generator 26 to the patient. Other suitable pressure/flow controllers are believed to be well known to those skilled in the art. For example, U.S. Pat. No. 6,615,831, the contents of which are incorporated herein by reference, teaches a sleeve valve suitable for use as the control valve of the present invention.
In embodiments in which pressure generator 26 is a blower that operates at all times at one speed, control valve 32 alone controls the final pressure for breathable gas 34 output from control valve 32 for delivery to a patient, which is typically accomplished via a flexible conduit. However, the present invention also contemplates controlling the operating speed of pressure generator 26 in combination with control valve 32 to control the final pressure and flow rate of the breathable gas delivered to the patient. For example, a pressure or flow rate close to the desired pressure or flow rate can be set by establishing an appropriate operating speed for pressure generator 26 along with control valve 32 so that the two, operating together, determine the final pressure for the breathable gas 34.
The pressure of the pressurized flow of breathable gas is measured by a pressure sensor 36. In the embodiment of
In the embodiment of
As shown, gas delivery system 16 includes a delivery system processor 40 that controls the various operating aspects of gas delivery system 16. For example, the output of flow sensor 38 and pressure sensor 36 are provided to delivery system processor 40 for processing, if needed, to determine the pressure of the breathable gas, the instantaneous volume (V) of breathable gas, and/or the instantaneous flow rate (V′) of the breathable gas. In some instances, the delivery system processor 40 determines the instantaneous volume by integrating the measured flow rate measured by flow sensor 38. Because, in one embodiment, the flow sensor 38 may be located relatively far from the location at which the breathable gas is delivered to the patient, in order to determine the actual flow rate of gas to the patient (or the actuation flow rate of gas from the patient—which is considered a negative flow), delivery system processor 40 receives the output from flow sensor 38 as an estimated flow. The delivery system processor 40 processes this estimated flow information, for example, by performing leak estimation, to determine the actual flow at the patient's airway, as is known to those skilled in the art.
A delivery system control interface 42 provides data and commands to delivery system processor 40 of gas delivery system 16. Delivery system control interface 42 may include any device suitable to provide information and/or commands to delivery system processor 40 via a hardwire or wireless connection. Typical examples of delivery system control interface 42 may include a keypad, keyboard, touch pad, mouse, microphone, switches, button, dials, or any other devices that allow a user to input information to the gas delivery system 16. Interface 42 can also include hardwired or wireless techniques for communicating information and/or commands with processor 40, such as a serial port, parallel port, USB, port, RS-232 port, smart card terminal, modem port, etc.
Delivery system processor 40 controls pressure generator 26 and the actuation of control valve 32, thereby controlling the pressure of the pressurized flow of breathable gas generated by the gas delivery system 16. In one embodiment, delivery system processor 40 comprises a processor that is suitably programmed with the necessary algorithm or algorithms to calculate the pressure to be applied to the patient according to one of any one of various modes of ventilation. In addition, the processor 40 may be capable of controlling pressure generator 26 and/or control valve 32 based on data received from pressure sensor 36 and/or flow sensor 38 to apply the calculated pressure to the breathable gas within gas delivery system 16. In one embodiment of the present invention, the gas delivery system 16 includes a memory 44 associated with delivery system processor 40 for storing the programming necessary to perform any of a plurality of modes of ventilation, depending on which mode of ventilation is selected by the caregiver or patient using delivery system control interface 42. Memory 44 may also be capable of storing data regarding the operation of the gas delivery system 16, input commands, alarm thresholds, as well as any other information pertinent to the operation of the gas delivery system 16, such as measured values of gas flow, volume, pressure, device usage, operating temperatures, and motor speed.
An alternative embodiment of gas delivery system 16 is discussed below with reference to
The present invention further contemplates that gas delivery system 16 or 16′ and related components can include other conventional devices and components, such as a humidifier, heater, bacteria filter, temperature sensor, humidity sensor, and a gas sensor (e.g., a capnometer), that filter, measure, monitor, and analyze the flow of gas to or from the patient.
The flow of the pressurized flow of breathable gas is measured by a first flow sensor 46 associated with oxygen regulator assembly 20. First flow sensor 46 may be disposed at any location upstream from a junction 48, at which the pressurized flow of breathable gas is combined with supplemental oxygen from oxygen source 24. Although first flow sensor 46 is illustrated in
As shown in
The valving of oxygen control valve 50 may include one or more solenoid driven control valves capable providing a desired amount of flow. For instance, control valve 50 may include a plurality of small, off-the-shelf, normally-closed, spring-return poppet valves (driven by a solenoid) such as those manufactured by Pneutronics, Inc. For example, each valve may provide approximately 35 L/min. of flow at 35 psi drive pressure, and, in one embodiment, three valves may be used. The three valves may be wired such that driving control for the valves can be applied simultaneously to each valve. The aforementioned valves manufactured by Pneutronics are designed to open at a precise current level, thereby circumventing the problem of control non-linearities associated with an arrangement in which all valves do not open simultaneously.
In one embodiment, the filter/regulator of oxygen control valve 50 may be configured and arranged to preclude the type of accumulation of particles in oxygen control valve 50 that would cause the valving to stick open and permit oxygen leakage.
The filter/regulator may further be configured and arranged to throttle down the drive pressure of the supplemental oxygen to a desirably low level, such as 50 psi, to reduce the variability of inadvertent design variations (e.g., manufacturing defects) that could otherwise have an effect on the supply pressure or controllability of the valving. For example, the filter/regulator may include a “bowl”-type filter/regulator manufactured by Parker-Hannifin.
In the embodiment of
Second flow sensor 52 is disposed downstream from oxygen control valve 50 in order to monitor the flow rate of the supplemental oxygen being directed to junction 48 for combination with the pressurized flow of breathable gas.
The combination of the pressurized flow of breathable gas 18 and the supplemental oxygen 24 at junction 48 forms a flow of oxygenated gas that is delivered to the patient via a patient circuit 54, which is typically a single flexible conduit that carries the flow of breathing gas to a patient interface assembly 56. In the illustrated embodiment, the patient interface assembly 56 and/or patient circuit 54 includes a suitable exhaust port 58 for exhausting gas from these components to ambient atmosphere. Exhaust port 58 is preferably a passive exhaust port in the form of a continuously open port that imposes a flow restriction on the exhaust gas to permit control of the pressure of gas within patient interface assembly 56. It is to be understood, however, that exhaust port 58 can be an active exhaust port that assumes different configurations to control the exhaust rate. Examples of suitable exhaust ports are taught, for example, in U.S. Pat. Nos. 5,685,296 and 5,937,855 hereby incorporated by reference.
The present invention contemplates that in an embodiment (not illustrated), the patient circuit 54 can be a two-limb circuit, which is common in conventional ventilators. In a two-limb circuit, the first limb, like patient circuit 54, delivers oxygenated gas to the patient, except that it lacks an exhaust port. Instead, a second limb carries the exhaust gases from the patient to ambient atmosphere. Typically, an active exhaust port in the second limb under the control of a controller (e.g. regulator processor 60) provides the desired level of positive end expiratory pressure (PEEP) to the patient.
As shown, oxygen regulator assembly 20 includes a regulator processor 60 that controls the various operating aspects of oxygen regulator assembly 20. For example, the output of first flow sensor 46 and second flow sensor 52 are provided to regulator processor 60 for processing, if needed, to determine and/or regulate the flow rate (V′) of the pressurized flow of the breathable gas and the supplemental oxygen.
A regulator control interface 62 provides data and commands to regulator processor 60 of oxygen regulator assembly 20. Regulator control interface 62, may include any device suitable to provide information and/or commands to regulator processor 60 via a hardwire or wireless connection. Typical examples of regulator control interface 62 may include a keypad, keyboard, touch pad, mouse, microphone, switches, button, dials, or any other devices that allow a user to input information to the oxygen regulator assembly 20. Regulator control interface 62 can also include hardwired or wireless techniques for communicating information and/or commands with processor 60, such as a serial port, parallel port, USB, port, RS-232 port, smart card terminal, modem port, etc.
In one embodiment of the invention, the patient, or another individual, enters an oxygen concentration level setpoint using regulator control interface 62. Based on the oxygen concentration level setpoint entered at regulator control interface 62, regulator processor 60 controls the flow of supplemental oxygen such that the oxygen concentration level of the oxygenated gas delivered to the patient is substantially equal to the oxygen concentration setpoint. More particularly, regulator processor 60 controls the actuation of oxygen control valve 50, thereby controlling the flow rate of the supplemental oxygen delivered from oxygen source 24 to junction 48.
In one embodiment of the present invention, oxygen regulator assembly 20 includes a memory 64 associated with regulator processor 60 for storing the programming necessary to perform these and other functionalities. Memory 64 may also be capable of storing data regarding the operation of the oxygen regulator assembly 20, such as input commands, alarm thresholds, as well as any other information pertinent to the operation of the oxygen regulator assembly 20, such as measured values of gas flow, volume, pressure, device usage, and operating temperatures.
According to one embodiment of the invention, regulator processor 60 comprises a processor that is suitably programmed with the necessary algorithm or algorithms to calculate the flow rates of the breathable gas and the supplemental oxygen, and the oxygen concentration level of the oxygenated gas that is delivered to the patient, and is capable of controlling oxygen control valve 50 based on data received from first flow sensor 46 and/or second flow sensor 52 to supply the supplemental oxygen at a flow rate that will ensure that the oxygen concentration level of the oxygenated gas is maintained substantially equal to the oxygen concentration level setpoint.
For example, regulator processor 60 may determine an oxygen flow rate setpoint that represents the flow rate of the supplemental oxygen that will ensure that the oxygen concentration level of the oxygenated gas delivered to the patient will be substantially equal to the oxygen concentration level setpoint according to the following equation:
where Qapp is the oxygen flow rate setpoint, Qbg is the measured flow rate of the breathable gas as measured by first flow sensor 46, Φbg is the oxygen concentration level of the breathable gas (e.g., 0.79 for ambient atmosphere), and Φset is the oxygen concentration level setpoint entered at regulator control interface 62. Regulator processor 60 then controls oxygen control valve 50 such that the flow rate of the supplemental oxygen from oxygen source 24 is provided at a flow rate substantially equal to the calculated oxygen concentration setpoint. In order to enhance the precision of the combination of the supplemental oxygen with the breathable gas, regulator processor 60 may control oxygen control valve 50 in a feedback loop, that implements the flow rate measured by second flow sensor 52, to correct for discrepancies between the calculated oxygen flow rate setpoint and the measured flow rate.
where Qgas is the flow rate of the oxygenated gas as measured by first flow sensor 46′.
It should be appreciated that the configurations of flow sensors 46 and 52 shown in
Because delivery system processor 40 of gas delivery system 16 controls the generation of the pressurized flow of breathable gas in a feedback manner based on pressure, and regulator processor 60 of oxygen regulator assembly 20 controls the supplemental oxygen based on measured flow rates, delivery system processor 40 and regulator processor 60 may operate independently without substantial communication therebetween. In other words, because control of the generation of the pressurized flow of breathable gas by gas delivery system 16 is based on pressure, the addition of supplemental oxygen into the system 10 by oxygen regulator assembly 20 will be detected by pressure sensor 36 as an increase in pressure, and the flow rate of the pressurized gas will automatically be adjusted accordingly so that the pressure of the total gas (oxygenated gas) delivered to the patient will be substantially unchanged by the added supplemental oxygen, even in embodiments in which delivery system processor 40 and regulator processor 60 are not operatively linked for communication of control, or other, signals. Similarly, changes in the flow rate of the pressurized flow of breathable gas made by gas delivery system 16 to hold the pressure of the gas delivered to the patient at a desired level will be detected by regulator processor 60 via first flow sensor 46, and may be accounted for by automatically adjusting the flow of supplemental oxygen in accordance with the detected change to maintain the oxygen concentration level of the oxygenated gas.
Although the processors 40 and 60 need not be in communication with each other in order for patient treatment system 10 to operate properly in accordance with the invention, an estimate by delivery system processor 40 (and subsequent reports to a user) with respect to the flow rate. and/or volume of the gas delivered to the patient in an embodiment in which processors 40 and 60 are not operatively linked may be somewhat less accurate because the estimate would not take into account the addition of the supplemental oxygen downstream from the gas delivery system 16. In one embodiment in which processors 40 and 60 are not operatively linked, oxygen regulator assembly 20 includes a visible indication on a housing associated therewith that the implementation of oxygen regulator assembly 20 with gas delivery system 16 will substantially affect estimates of flow rate and/or volume obtained from gas delivery system 16. The visible indication may include, for example, a pictorial representation, a written statement, or other visible indication. In another embodiment, oxygen regulator assembly 20 includes a similar visible indication and provides accurate estimates of the flow rate and/or volume of gas delivered to the patient via the regulator control interface 62.
Of course, while processor modules 40 and 60 need not be operatively linked for communication, in some embodiments, gas delivery system 16 and oxygen regulator assembly 20 may be in communication with each other, and may communicate various information regarding the generation of the flow of pressurized flow of breathable gas and/or the flow of the supplemental oxygen. For example, oxygen regulator assembly 20 may communicate the flow rate of the supplemental oxygen to gas delivery system 16 so that delivery system processor 40 can account for the supplemental oxygen in performing leak estimations, and/or for adjusting estimates with regard to the flow rate and/or volume of gas delivered to the patient.
It should be appreciated that the embodiments of oxygen regulator assembly 20 illustrated in
It should also be understood that while the present invention has been described above as delivering oxygen as the supplemental gas to the patient concurrently with the primary gas flow, other gas can be used as the supplemental gas. For example, it is known to deliver helium, a helium-oxygen mixture (heliox), nitrogen, a nitrogen-oxygen mixture (nitrox), a helium-oxygen-nitrogen mixture (trimix), or any other gas or combination of gasses to a patient. These gasses or combination of gasses can be used as supplemental gas 22 that is combined with the primary gas flow. The descriptions given above for setting the gas concentration levels of the supplemental are applicable for these other types of gas or gas mixtures, and the hardware remains the same. The main difference being that gas source 24 is not an oxygen source, but the source for the other gas or gas mixture being introduced to the patient.
Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred embodiments, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.
This application claims priority under 35 U.S.C. §119(e) from provisional U.S. patent application No. 60/697,744 filed Jul. 8, 2005, the contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60697744 | Jul 2005 | US |
