Non-invasive breathing assistance apparatus and method
An nCPAP device for assisting patient breathing includes a generator body forming an inlet, a chamber, and first and second flow circuits. The chamber directs pressurized gas from the inlet to the flow circuits. The flow circuits each include a nozzle, a channel, and at least one port. The nozzle emits a jet stream into the channel in a direction of a patient side thereof. The port fluidly connects the channel to ambient, and promotes entrainment of ambient air with the jet stream. In some embodiments, the channel forms a ramp feature directing exhaled air toward the jet stream in an angular fashion. The generator body requires reduced driving pressures to achieve target CPAP levels and reduces total imposed WOB as compared to conventional designs.
1. A nasal continuous positive airway pressure device for use in a CPAP system to assist patient breathing, the device comprising:
a generator body forming:
a gas supply inlet for fluid connection to a source of pressurized gas;
a chamber fluidly connected to the gas supply inlet; and
first and second flow circuits fluidly connected to the chamber, each of the flow circuits including:
a nozzle defining an inlet end and an outlet end, the inlet end fluidly connected to the chamber;
a channel comprising a tubular body having a nozzle side fluidly connected to the outlet end of the nozzle and a patient side opposite the nozzle side for directing gas to and from a patient's naris;
a first port fluidly connected to the channel at a first interior aperture and connected to ambient air via a first exterior aperture in the generator body; and
a second port fluidly connected to the channel at a second interior aperture and connected to the ambient air via a second exterior aperture,
wherein the nozzle is configured to create a jet stream from pressurized gas in the chamber, the jet stream being deliverable to the channel and divertible to the first and second ports,
wherein in longitudinal cross-section, the channel of each of the flow circuits is defined by a lower wall surface opposite an upper wall surface, the corresponding first port being formed in the upper wall surface and the corresponding second port being formed in the lower wall surface,
wherein a cross-sectional area of the first port at the first interior aperture is greater than a cross-sectional area of the second port at the second interior aperture and a cross-sectional area of the first port at the first exterior aperture is greater than a cross-sectional area of the second exterior aperture, and wherein the first port is configured to facilitate a greater volumetric gas flow than the second port.
2. The device of claim 1 , further comprising a patient interface piece fluidly coupled to the patient side of the channels.
3. The device of claim 1 , wherein the gas supply inlet is arranged perpendicularly to the channel.
4. The device of claim 3 , wherein the second exterior aperture is in the tubular body of the channel, the second exterior aperture is fluidly connected to a second chamber defined between inner and outer housing sections of the generator body, and the second chamber is fluidly connected to ambient air via a passageway through the generator body.
5. The device of claim 1 , wherein the gas supply inlet is arranged parallel to the channel.
6. The device of claim 5 , wherein the second port is fluidly connected directly to the ambient air via the second exterior aperture formed in the generator body.
7. The device of claim 1 , wherein the first port is defined by a leading end wall proximate the nozzle and a trailing end wall proximate the channel, wherein the leading end wall tapers inwardly from the exterior aperture to the interior aperture, wherein the trailing end wall extends between the interior and exterior apertures, and wherein the first port has an expanding cross-sectional area from the channel to the first exterior aperture.
8. The device of claim 1 , further comprising an angled guide surface defined between the nozzle side of the channel and the second interior aperture, wherein the channel has an increasing diameter between the nozzle and the second port.
9. The device of claim 1 , wherein the generator body is configured to establish:
an inspiratory flow pattern during an inspiratory stage of breathing, the inspiratory flow pattern including gas flow from the chamber, along each of the first and second flow circuits, and to the patient side of each of the channels; and
an expiratory flow pattern during an expiratory stage of breathing, the expiratory flow pattern including gas flow from the patient side of each of the channels primarily to the corresponding second ports, and including diversion of the jet stream to the corresponding first ports.
10. The device of claim 9 , wherein gas flow directed toward the nozzle as part of the expiratory flow pattern diverts the jet stream to the first port.
11. A nasal continuous positive airway pressure system for assisting patient breathing, the system comprising:
a generator body forming:
a gas supply inlet;
a chamber fluidly connected to the gas supply inlet;
first and second flow circuits fluidly connected to the chamber, each of the flow circuits including:
a nozzle defining an inlet end and an outlet end, the inlet end fluidly connected to the chamber;
a channel having a nozzle side fluidly connected to the outlet end of the nozzle and a patient side opposite the nozzle side for directing gas to and from a patient's naris;
a first port fluidly connected to the channel at a first interior aperture and connected to ambient air via a first exterior aperture in the generator body; and
a second port fluidly connected to the channel at a second interior aperture and connected to ambient air via a second exterior aperture;
a patient interface piece fluidly connected to the patient side of the channels, respectively; and
a source of pressurized gas fluidly connected to the gas supply inlet,
wherein upon securement of the patient interface piece to a patient's nares, the system is configured to generate a continuous positive airway pressure in the patient by delivering gas from the source of pressurized gas to the nozzles that in turn emits a gas jet stream within the corresponding channel in a direction of the patient interface piece,
wherein in longitudinal cross-section, the channel of each of the flow circuits is defined by a lower wall surface opposite an upper wall surface, the corresponding first port being formed in the upper wall surface and the corresponding second port being formed in the lower wall surface,
wherein a cross-sectional area of the first port at the first interior aperture is greater than a cross-sectional area of the second port at the second interior aperture and a cross-sectional area of the first port at the first exterior aperture is greater than a cross-sectional area of the second exterior aperture, and wherein the first port is configured to facilitate a greater volumetric gas flow than the second port.
12. The system of claim 11 , wherein the gas supply inlet is arranged perpendicularly to the channel, wherein the second exterior aperture is in a body of the channel, wherein the second exterior aperture is fluidly connected to a second chamber defined between inner and outer housing sections of the generator body, and wherein the second chamber is fluidly connected to ambient air via a passageway through the generator body.
13. The system of claim 11 , wherein the gas supply inlet is arranged parallel to the channel, and wherein the second port is fluidly connected directly to the ambient air via the second exterior aperture formed in the generator body.
14. The system of claim 11 , wherein the first port is defined by a leading end wall proximate the nozzle and a trailing end wall proximate the channel, wherein the leading end wall tapers inwardly from the exterior aperture to the interior aperture, wherein the trailing end wall extends between the interior and exterior apertures, and wherein the first port has an expanding cross-sectional area from the channel to the first exterior aperture.
15. The system of claim 11 , further comprising an angled guide surface defined between the nozzle side of the channel and the second interior aperture, wherein the channel has an increasing diameter between the nozzle and the second port.
16. The system of claim 11 , wherein the generator body is configured to establish:
an inspiratory flow pattern during an inspiratory stage of breathing, the inspiratory flow pattern including gas flow from the chamber, along each of the first and second flow circuits, and to the patient side of each of the channels; and
an expiratory flow pattern during an expiratory stage of breathing, the expiratory flow pattern including gas flow from the patient side of each of the channels primarily to the corresponding second ports, and including diversion of the jet stream to the corresponding first ports by the gas flow from the patient side.