Surgery – Respiratory method or device – Means for supplying respiratory gas under positive pressure
Reexamination Certificate
1999-07-02
2003-09-09
Lo, Weilun (Department: 3761)
Surgery
Respiratory method or device
Means for supplying respiratory gas under positive pressure
C128S204220, C128S204240, C128S205240, C128S204190
Reexamination Certificate
active
06615831
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to a pressure support system and a method of providing pressure support to a patient, and, more particularly, to a pressure support system and method having enhanced noise reduction, as well as a pressure control valve assembly for use in a pressure support system.
2. Description of the Related Art
Pressure support systems that provide a flow of gas to an airway of a patient at an elevated pressure via a patient circuit to treat a medical disorder are well known. For example, it is known to use a continuous positive airway pressure (CPAP) device to supply a constant positive pressure to the airway of a patient to treat obstructive sleep apnea (OSA). It is also known to provide a positive pressure therapy in which the pressure of gas delivered to the patient varies with the patient's breathing cycle or varies with the patient's effort to increase the comfort to the patient. It is further known to provide a positive pressure therapy in which the pressure provided to the patient changes based on the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea or upper airway resistance.
Conventional pressure support devices typically include a pressure generator, for example, a blower, piston, or bellows, that creates a flow of breathing gas at a pressure greater than the ambient atmospheric pressure. A patient circuit delivers the elevated pressure breathing gas to the airway of the patient. Typically, the patient circuit includes a conduit, e.g., a single limb or lumen, having one end coupled to the pressure generator and a patient interface device coupled to the other end of the conduit. The patient interface connects the conduit with the airway of the patient so that the elevated pressure gas flow is delivered to the patient's airway. Examples of patient interface devices include a nasal mask, nasal and oral mask, full face mask, nasal cannula, oral mouthpiece, tracheal tube, endotracheal tube, or hood. A single limb patient circuit includes an exhalation port, also referred to as an exhalation vent, exhaust port, or exhaust vent, to allow expired gas from the patient to exhaust to atmosphere. Generally, the exhaust vent is located in the conduit near the patient interface or in the patient interface device itself.
Many of these pressure support devices are used at night, especially where the function of the pressure support system is to treat a breathing disorder that occurs during sleep, such a sleep apnea. For this reason, the pressure support system must be quiet so as not to arouse the user or the user's bed partner. One source of noise addressed by the present invention is the exhaust assembly downstream of the pressure generator, which exhausts gas from the patient circuit to atmosphere. This is typically done in order to maintain the correct pressure or flow in the patient circuit. Typically, this exhaust assembly and associated exhaust path are located within a housing that contains the pressure generator.
Conventional pressure support devices with this configuration attempt to minimize noise due to exhausting of gas through the pressure control valve assembly to atmosphere by providing a dedicated muffler in the exhaust path. However, such a muffler is disadvantageous in that it adds significant cost, size, and weight to the pressure support system.
An example of a conventional pressure support system
1
with this configuration is shown in FIG.
1
. The conventional system includes a blower assembly
2
having a blower housing
3
, a fan
4
contained within the blower housing, a motor
5
for driving fan
4
, an inlet or intake
6
, and an outlet
8
. These features are collectively referred to as a pressure generator
7
. Inlet
6
is coupled to a first conduit
10
that communicates the inlet of the blower assembly to atmosphere. Outlet
8
of blower assembly
2
is coupled to a second conduit
12
that communicates a flow of breathing gas having an elevated pressure relative to ambient atmosphere created by the blower assembly to a third conduit
13
for delivery to a patient
20
. A single housing
15
, generally identified by the dashed line in
FIG. 1
, houses the components of the pressure support system.
Third conduit
13
has a first end
14
coupled to an end of second conduit
12
opposite outlet
8
. Third conduit
13
also has a second end
16
, opposite first end
14
, that is coupled to a patient interface
18
, which can be secured to patient
20
in a manner known in the art. Third conduit
13
is typically a flexible conduit to allow the patient to move freely while using the pressure support system. All of the conduits and devices for delivering the flow of breathing gas from the blower assembly to the patient's airway define a patient circuit
19
. In the embodiment illustrated in
FIG. 1
, patient circuit
19
includes second conduit
12
, third conduit
13
, and patient interface
18
.
During operation, motor
5
drives fan
4
, thereby creating, at intake
6
, a negative pressure relative to the pressure of the fluid, e.g., air, in the ambient atmosphere. In response to this negative pressure, fluid in the ambient atmosphere is drawn through first conduit
10
and intake
6
into blower housing
3
, wherein the operation of fan
4
increases the pressure of the fluid. The fluid pressurized by fan
4
is delivered from blower housing
3
at outlet
8
into second conduit
12
. The pressurized fluid flows through third conduit
13
to patient interface
18
for receipt by patient
20
. An exhaust port
22
is provided at second end
16
of third conduit
13
for exhausting gases, such as the exhaled gases from the patient, to ambient atmosphere. Exhaust port
22
can have a variety of configurations that are well known in the art, and can be provided in third conduit
13
, as shown, or in patient interface
18
.
As noted above, there are many instances where it is desirable to control the pressure, and, hence, the flow of fluid, delivered to the patient by the pressure support system. For example, it is known to provide a continuous positive airway pressure “CPAP” device with the ability to change the pressure or flow of fluid delivered to the patient so that a commonly designed device can be used to provide pressure support therapy to patients with different pressure support prescription levels. Typically, the patient's therapy pressure is determined in a sleep study and then the CPAP device prescribed and is set to output that prescription pressure at all time during its operation. An example of a CPAP device that operates in this manner is the REMstar® and Solo® family of devices manufactured and distributed by Respironics, Inc. of Pittsburgh, Pa.
Unlike a CPAP device, which outputs a constant pressure at all times during its operation, it is also known, as described above, to provide a pressure support therapy in which the pressure of breathing gas delivered to the patient varies during the course of treatment. For example, it is known to vary the pressure of breathing gas delivered to the patient in synchronization with the patient's breathing cycle so that a lower pressure is delivered to the patient during the expiratory phase of the breathing cycle than is delivered during the inspiratory phase, so that the patient is not breathing out against a relatively high pressure. This mode of pressure support is typically referred to as “bi-level” pressure support. Examples of pressure support devices that have the ability to operate in this bi-level mode of ventilation are the BiPAP® family of devices manufactured and distributed by Respironics, Inc.
It is also known to vary the pressure of breathing gas provided to the patient based on the detected conditions of the patient, such as whether the patient is snoring or experiencing an apnea, hypopnea, or upper airway resistance. This mode of pressure support is typically referred to as “auto” or “smart” pressure support because
Gesner Joseph J.
Lordo Richard J.
Tuitt Patrick W.
Haas Michael W.
Lo Weilun
Mendoza Michael
Respironics Inc.
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