Portable ventilator

• US 7,032,589 B2
• Filed: 01/23/2003
• Issued: 04/25/2006
• Est. Priority Date: 01/23/2002
• Status: Active Grant

• Current Assignee: Johns Hopkins University
• Original Assignee: Johns Hopkins University
• Inventors: Cutchis, Protagoras N., Nix, Jennifer A., Kerechanin, Charles W. II, Smith, Dexter G.
• Primary Examiner(s): Bennett, Henry
• Assistant Examiner(s): DOSTER GREENE, DINNATIA JO
• Application Number:
  US10/349,628
• Publication Number:
  US 20030172931A1
• Time in Patent Office: 1,188 Days
• Field of Search: 181/403, 181/60, 181/248, 181/483, 181/231, 128/205.18, 128/202.12, 128/204.18, 128/204.26, 128/201.25, 128/200.24, 128/204.21, 415/119, 417/312
• US Class Current: 128/200.24
• CPC Class Codes: A61M 16/00 Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61H31/00
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/0069 the speed thereof being controlled by respiratory parameters, e.g. by inhalation
• CPC Class Codes: A61M 16/022 Control means therefor
• CPC Class Codes: A61M 16/107 in the inspiratory path
• CPC Class Codes: A61M 16/202 electrically actuated
• CPC Class Codes: A61M 16/206 Capsule valves, e.g. mushroom, membrane valves
• CPC Class Codes: A61M 16/208 Non-controlled one-way valves, e.g. exhalation, check, pop-off non-rebreathing valves
• CPC Class Codes: A61M 16/209 Relief valves
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2016/0042 in the expiratory circuit
• CPC Class Codes: Y10S 181/403 Refrigerator compresssor muffler

Abstract

A portable ventilator for providing an air-recipient with compulsory respiration is provided with an outlet manifold and a single-expansion-chamber muffler configured so that airflow through an inhale outlet port of the muffler is pulse-free and a transmission loss, defined as the ratio of sound power generated by the at least one compressor and incident on the muffler to the sound power transmitted by the muffler, is sufficient to deaden the sound power of the compressor.

Claims

1. A portable ventilator for providing an air-recipient with compulsory inspiration, comprising:

at least one compressor for controllably supplying compressed air along an output air path of the ventilator in an upstream to downstream direction towards the air recipient;

an outlet manifold located along the ventilator output air path downstream from the at least one compressor and in direct flow communication therewith; and

a single-expansion-chamber outlet muffler located along the ventilator output air path downstream from the outlet manifold and in direct flow communication with the air-recipient and with the manifold outlet, whereby the compressed air from the compressor passes through the manifold outlet, the muffler and then an inhale port of the muffler toward the air-recipient, the muffler and the manifold outlet being configured so that airflow through the inhale outlet port of the muffler is substantially pulse free and a transmission loss, defined as the ratio of sound power generated by the at least one compressor and incident on the outlet muffler to the sound power transmitted by the muffler, is sufficient to deaden the sound power of the at least one compressor.

2. The portable ventilator of claim 1, wherein the outlet muffler and the outlet manifold form an outlet one-piece manifold/muffler assembly, which further comprises an inlet manifold located upstream from the at least one compressor so as to be traversed by incoming outer air that is to be compressed by the at least one compressor, wherein the inlet manifold is configured to supply the incoming air to an input of the compressor.

3. The portable ventilator of claim 2, wherein the at least one compressor is juxtaposed with the outlet manifold, the ventilator further comprising a plurality of substantially straight, short and uniformly dimensioned air-conveying conduits extending between and in flow communication with the at least one compressor and the outlet manifold.

4. The portable ventilator of claim 2, further comprising a front panel coupled to the one-piece manifold/muffler assembly and provided with the inhale outlet port, and a back panel spaced from the front panel and provided with an air inlet port, which is configured to be traversed by incoming air in response to actuation of the at least one compressor and is in flow communication therewith through the inlet manifold.

5. The portable ventilator of claim 4, further comprising a mount plate coupled to the front and back panels and supporting at least one compressor, and a controller coupling the at least one compressor with a power source and operative to actuate the at least one compressor so as to supply a desired volume of compressed air through the outlet of the outlet manifold, the muffler and via the inhale port to the air recipient during an inspiration stroke thereof.

6. The portable ventilator of claim 5, further comprising a volume regulator coupled to the controller and operative to set a reference value, below which the at least one compressor operates in a low-volume mode of operation of the portable ventilator.

7. The portable ventilator of claim 5, wherein the power source is either internal or external, the internal power source being a rechargeable battery provided with an adapter connectable to the external power source and located on the back panel.

8. The portable ventilator of claim 6, further comprising an auxiliary compressor detachably mounted on the mount plate and coupled with the controller so that the at least one and auxiliary compressors produce high volume of compressed air delivered to the air recipient through the outlet of the outlet manifold, the muffler and via the inhale port in response to a signal generated by the volume regulator and exceeding the reference value.

9. The portable ventilator of claim 6, wherein the at least one and auxiliary compressors operate in parallel.

10. The portable ventilator of claim 6, further comprising an one-way exhale valve mounted on the front panel and coupled to the controller to provide flow of wasted gases from the air recipient during an expiration stroke thereof.

11. The portable ventilator of claim 10, further comprising a micro air pump coupled to the controller and in flow communication with an outlet of the one-way exhale valve to create a pressure sufficient to open the one-way exhale valve in response to a control signal generated by the controller upon termination of airflow from the at least one compressor via the outlet of the outlet manifold and through the muffler during the inspiration stroke of the air recipient.

12. The portable ventilator of claim 11, further comprising a flow control sensor coupled to the controller and operative to determine termination of airflow during the inspiration stroke and to output a signal in response to which the controller generates the control signal activating the micro air pump.

13. The portable ventilator of claim 10, further comprising a safety valve operative to bleed in response to a build-up pressure exceeding a reference value to prevent the lungs of the air recipient from overpressurization.

14. The portable ventilator of claim 4, further comprising an inlet manifold/muffler assembly including

a respective single-chamber muffler in flow communication with at least one compressor, and

an upstream manifold providing flow communication between the air inlet port and the single-chamber muffler of the inlet manifold/muffler assembly,

the inlet manifold/muffler assembly being formed in the back panel and being configured substantially identically to the outlet manifold/muffler assembly to reduce the transmission loss upstream from the at least one compressor.

15. The portable ventilator of claim 1, wherein the transmission loss is calculated in terms of two parameters m and kl calculated according to the following:

$L_{\mathrm{TL}}=10<br><br>\log <br><br>\left[1+\frac{1}{4}<br><br>{\left(m-\frac{1}{m}\right)}^2<br><br>{\sin }^2<br><br>k<br><br><br><br>l\right],$

wherein the parameter m is the ratio of the cross-sectional area of the single-chamber muffler to the cross-sectional area of inlet opening and the parameter kl is given as a ratio of 2 pi times the length of the muffler divided by the wavelength according to the following;

$k<br><br><br><br>l=\frac{2<br><br><br><br>\mathrm{\pi <br><br>}<br><br><br><br>l}{\mathrm{\lambda <br><br>}}$

16. The portable ventilator of claim 15, wherein the parameter m ranges between 100 and 200 and the parameter kl varies from 0.1 to 0.4 to achieve a transmission loss of around 19 to 24 dB.

17. A portable ventilator, comprising:

spaced front and back end plates;

at least one compressor located between the front and back end plates and operative to generate airflow along a path;

an inlet manifold/muffler assembly provided in the back panel and configured to be traversed by incoming air in response to actuation of the at least one compressor; and

an outlet manifold/muffler assembly coupled to the front panel and traversed by air flow directed towards an recipient, the inlet and outlet manifold/muffler assemblies having each a single-chamber muffler and an inlet opening located upstream from and in direct flow communication with a respective single-chamber muffler, wherein the inlet and outlet manifold/muffler assemblies are configured to decrease an acoustic signal generated by the at least one compressor along upstream and downstream ends of the path and to provide smooth constant airflow to the air recipient,

wherein the inlet manifold/muffler assembly includes a casing mounted to the front panel and including an upstream compartment which houses inlet and outlet manifolds, the inlet manifold located upstream from the at least one compressor and being in flow communication therewith and with the inlet manifold/muffler assembly, the outlet manifold formed with inlet opening of the being located downstream from the at least one compressor.

18. The portable ventilator of claim 17, wherein the back end plate is configured to form the single-chamber muffler of the inlet manifold/muffler assembly and to have a duct traversed by incoming air flow in response to activation of the at least one compressor and having the inlet opening.

19. The portable ventilator of claim 18, wherein the inlet and outlet manifold/muffler assemblies are each configured so that a transmission loss, defined as the ratio of sound power generated by the at least one compressor and incident on a respective single-chamber muffler to the sound power transmitted by the muffler, is sufficient to deaden the sound power of the at least one compressor.

20. The portable ventilator of claim 18, wherein the transmission loss is calculated in terms of two parameters m and kl calculated according to the following:

$L_{\mathrm{TL}}=10<br><br>\log <br><br>\left[1+\frac{1}{4}<br><br>{\left(m-\frac{1}{m}\right)}^2<br><br>{\sin }^2<br><br>k<br><br><br><br>l\right],$

wherein the parameter m is the ratio of the cross-sectional area of the single-chamber muffler to the cross-sectional area of manifold opening into the and the parameter kl is given as a ratio of 2 pi times the length of the muffler divided by the wavelength according to the following;

$k<br><br><br><br>l=\frac{2<br><br><br><br>\mathrm{\pi <br><br>}<br><br><br><br>l}{\mathrm{\lambda <br><br>}}$

21. The portable ventilator of claim 20, wherein the parameter m ranges between 100 and 140, the parameter kl varies from 0.1 to 0.4.

22. The portable ventilator of claim 17, further comprising an auxiliary compressor operative to be coupled in parallel to the at least one compressor.

23. The portable ventilator of claim 17, wherein the at least one compressor is juxtaposed with the outlet manifold/muffler assembly, which further includes a plurality of substantially straight, short and uniformly dimensioned air-conveying conduits providing air communication between the at least one compressor and the outlet manifold.