Abstract
The invention is related to a portable rebreathing system for closed rebreathing. In order to minimize consumption of oxygen during rebreathing mode while safeguarding correct oxygen concentration, oxygen is added into the breathing passage using staged addition of oxygen via at least three individual oxygen supply valves 51, 52, 53. The two first oxygen supply valves are calibrated nozzles where one nozzle 51 is constantly delivering a predetermined amount of oxygen during normal breathing and the second nozzle 52 adds more oxygen at a second predetermined amount when the person to be treated is breathing heavily. The third valve is only opened manually and delivers a short burst of oxygen that fills the rebreathing system and its counter lung within seconds.
Claims
1. A portable rebreathing system for closed rebreathing, said portable rebreathing system comprising a breathing mask, a common valve housing connected with a mask connector to the breathing mask; a carbon dioxide scrubber connected with a scrubber connector to the common valve housing; a counter lung connected with a counter lung connector to the carbon dioxide scrubber; an oxygen supply port and at least one ambient air port arranged in the common valve housing; a pressurized oxygen source connected to the oxygen supply port via a hose; wherein the oxygen supply port is in communication with at least three oxygen supply valves, and all oxygen supply valves have outlets emanating into an inhale flow passage in the common valve housing; and the first oxygen supply valve is a constant flow rate nozzle valve delivering oxygen through a small restriction at a first flow rate when the pressurized oxygen source is connected, and the second oxygen supply valve is a constant flow rate nozzle valve delivering oxygen through a small restriction at a second flow rate equal to or exceeding the first flow rate when inhalation is excessive, and the third oxygen supply valve is a nozzle valve delivering oxygen through a restriction at a third flow rate exceeding the first flow rate by at least 40 times when a manual activation knob in the common valve housing is pushed down.
2. A portable rebreathing system according to claim 1, wherein the oxygen supply port is in communication with a shut-off valve in the common valve housing closing an alternative breathing passage to the ambient port when oxygen pressure is applied in the oxygen supply port and opening an alternative breathing passage connected to an ambient air port when no oxygen pressure is applied in the oxygen supply port.
3. A portable rebreathing system according to claim 1, wherein a flexible membrane is arranged as a wall in the inhalation flow passage allowing deflection into the inhalation flow passage when a flow rate in the inhalation flow passage exceeds a predetermined level.
4. A portable rebreathing system according to claim 3, wherein the common valve housing has a cylindrical form and that the membrane is a cylindrical flexible disc with its periphery arranged fixed and sealed to the inside of the cylindrical common valve housing with one side of the membrane exposed to the inhalation flow passage in a narrow flow path that locally increases speed of flow and thus creates a lower pressure on the exposed side of the membrane.
5. A portable rebreathing system according to claim 3, wherein the flexible membrane deflects a pivot lever when the flow rate in the inhalation flow passage exceeds the predetermined level and said deflection of the pivot lever opens the second oxygen supply valve.
6. A portable rebreathing system according to claim 5, wherein the flexible membrane is also deflectable by a manual activation knob which knob when depressed fully deflects the pivot lever further such that the additional deflection of the pivot lever opens also the third oxygen supply valve.
7. A portable rebreathing system according to claim 1, wherein the first oxygen supply valve is a constant flow rate nozzle valve, with a calibrated bore through the nozzle delivering a constant flow at a rate of 0.5-1.5 liter of oxygen per minute.
8. A portable rebreathing system according to claim 1, wherein the second oxygen supply valve is a constant flow rate nozzle valve, with a calibrated bore through the nozzle delivering a constant flow at a rate of 1.0-2.0 liter of oxygen per minute.
9. A portable rebreathing system according to claim 1, wherein the third oxygen supply valve is a restriction which when opened delivers a constant flow at a rate of 10-100 liter of oxygen per minute.
10. A portable rebreathing system according to claim 9, wherein the third oxygen supply valve delivers a constant flow at a rate of 50-70 liter of oxygen per minute, and capable of filling the system and an expanded counter lung in 3 seconds.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] The foregoing aspects and advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying schematically drawings, wherein:
[0042] FIG. 1a shows a side view in a cross section of a first schematic embodiment of the rebreathing system according to the invention, here during an inhalation phase;
[0043] FIG. 1b shows same side view as in FIG. 1a but here during an exhalation phase;
[0044] FIG. 2a shows a flat view as well as a side view in a cross section of a valve seat member used in one embodiment of the invention;
[0045] FIG. 2b shows same views as in FIG. 2a but with valve members attached and breathing directly to atmosphere;
[0046] FIG. 2c shows same views as in FIG. 2b but in rebreathing mode during an exhalation phase;
[0047] FIG. 2d shows same views as in FIG. 2b but in rebreathing mode during an inhalation phase;
[0048] FIG. 3a shows a side view in a cross section of a first schematic embodiment of the common valve housing during normal breathing;
[0049] FIG. 3b shows the same view as in FIG. 3a but during excessive breathing;
[0050] FIG. 3c shows the same view as in FIG. 3b but during maximum activation of a manual activation knob;
[0051] FIG. 3d shows the same view as in FIGS. 3a-3c but with no oxygen pressure applied when breathing takes place directly to atmosphere;
[0052] FIG. 3e show an example of a constant flow rate nozzle valve;
[0053] FIG. 4a-4c shows the alternative breathing passage used in FIG. 3d with no oxygen pressure applied;
[0054] FIG. 5 shows a complete prototype of an embodiment of the invention.
[0055] However, it should be stressed that the drawings only visualize the concepts of the invention, as presentable in 2 dimensional drawings. Some channels may for instance utilize the option to be routed not only in the 2 dimensions shown, but also may be routed in 3 dimensions fully utilizing the total volume of the common valve housing. The pressurized oxygen source may be a bottle or an oxygen outlet in a hospital.
DETAILED DESCRIPTION OF THE ENABLING EMBODIMENTS
[0056] In FIG. 1a, a side view in a cross section of a first schematic embodiment of the rebreathing system according to the invention is shown, here during an inhalation phase. The inhalation flow through the rebreather is shown with arrows having a double flow line.
[0057] The rebreather has a breathing mask 4 that is to be applied over the mouth and nose of a person to be treated, said mask typically made in flexible rubber material like silicone rubber.
[0058] The breathing mask 4 is in turn connected to a bio-filter 6 with a mask connector 4a gripping over a congruent circular connector of the bio-filter with a press fit. The bio-filter is connected to the common valve housing X with a similar connection. The bio-filter is used to avoid ingress of biological material, like vomit from a person to be treated as well as bacteria. After usage may the bio-filter be exchanged and the non-contaminated rebreathing kit may be used for another person, not needing sterilization of the common valve housing.
[0059] The common valve housing X has an inhalation flow passage 10 and an exhalation flow passage 20. If the inhalation phase is to start in FIG. 1a is a counter lung 2 inflated, and during the inhalation phase, breathing air is drawn from the counter lung 2 through a carbon dioxide scrubber 3 and further on passing over a membrane 55 in the common valve housing X. The inhalation flow is thereafter diverted 90 degrees into a channel 10 and passing a first one-way check valve 11. The check valve 11 is typically made in rubber and may have any suitable form as a rhomboid or circular form. The counter lung 2 is simply a flexible bag in polymeric material and is attached with a counter lung connector 2a to the carbon dioxide scrubber in the same manner as the connector 4a for the breathing mask. The counter lung 2 expands in the direction E during the exhalation and retracts in the direction I during inhalation. The carbon dioxide scrubber is filled with any active material that binds CO.sub.2, typically in powder form, with diffusors 3b in both ends. The upper end of the carbon dioxide scrubber is also equipped with a fine mesh filter 3c that prevents scrubber material from entering the common valve housing.
[0060] The common valve housing X is also equipped with an oxygen supply port 5, and a manual activation knob 54, which will be more described later.
[0061] In FIG. 1b a side view is shown in a cross section of the first schematic embodiment of the rebreathing system according to the invention, here during an exhalation phase. The exhalation flow through the rebreather is shown with arrows having a double flow line. In contrast to the flow pattern shown in FIG. 1 is the exhalation flow opening a second one-way check valve 21 into an exhalation flow passage 20, while the increase pressure during exhalation closes the first one-way check valve 11. The exhalation flow is diverted through the carbon dioxide scrubber 3 and finally to the counter lung 2.
[0062] In FIGS. 2a to 2d the valve seat member 8 and associated valves during different phases of breathing are shown schematically. FIG. 2a shows a flat view as well as a side view in a cross section of the valve seat member 8 alone. The valve seat member has a first opening for an alternative breathing passage 7 open when no oxygen addition is activated and an opening for the inhalation flow passage 10 as well as an opening for the exhalation flow passage 20. In this embodiment the inhalation and exhalation passages have a rhomboid form enabling the largest flow area in these passages when the common valve housing has a tubular form, but these passages may equally well be circular. FIG. 2b shows same views as in FIG. 2a but with valve members attached and breathing directly to atmosphere in an alternative breathing passage 7. A shut off valve 7a is open as long as no oxygen pressure is connected and the one-way check valve 21 is closed as no pressure could build up on the valve 21. FIG. 2c, shows same views as in FIG. 2b but in rebreathing mode during an exhalation phase. When rebreathing is to be activated is simply oxygen pressure applied on the shut-off valve (as indicated with the grey arrow), and then the pressure builds up on the one-way check valve 21 and will open it to the exhalation flow passage. FIG. 2d, shows same views as in FIG. 2b but in rebreathing mode during an inhalation phase, and then the pressure drops on the one-way check valve 11 and will open the inhalation flow passage.
[0063] The functionality of the common valve housing X will be described more in detail with reference to FIGS. 3a to 3d. In order to simplify, the schematic cross section is made through the inhalation and exhalation flow passages 10 and 20, even though they may be located in the clock positions 4 and 8 as shown in FIG. 2a.
[0064] FIG. 3a shows a side view in this schematic cross section of a first schematic embodiment of the common valve housing during activated rebreathing with addition of oxygen. A pressure chamber 5c is pressurized with oxygen at any selected pressure added via an oxygen supply port 5 in the common valve housing X. Typically, the pressure in the pressure chamber is regulated to a level of 4 bar, using any standard pressure regulator between the oxygen source and the common valve housing X. This pressure chamber is in direct communication with; [0065] a first oxygen supply valve 51, [0066] a second oxygen supply valve 52, [0067] a third oxygen supply valve 53, and [0068] a piston connected to a spring biased shut-off valve 7a.
[0069] During normal breathing, only the first oxygen supply valve 51 is open as indicated in FIG. 3a. This first oxygen supply valve delivers a constant flow of oxygen at a constant flow rate of about 0.5-1.5 liter of oxygen per minute when the connection to the oxygen source has been made. Typically, 1 liter of oxygen per minute is fully sufficient for replacing the amount of CO.sub.2 in the exhaled air for an adult person when breathing normally. The first oxygen supply valve 51 is a constant flow rate nozzle valve with a calibrated bore that are available as standard nozzles and could be replaced if needed. However, this calibrated nozzle safeguards the efficient use of available oxygen for maximum length of usage and minimum consumption.
[0070] FIG. 3b shows the same view as in FIG. 3a but during excessive breathing. In this state, the person treated is most often hyperventilating. The flow of inhalation air increases and that causes a pressure drop over the flexible membrane 55 that deflects to a position 55x as indicated in FIG. 3b. The passage over the membrane may preferably be designed as a narrow throat that increase speed of passing air and this increase the pressure drop. During this deflection, the flexible membrane 55 is pushing a pivot lever 56 around a pivot point 56a and against a pivot spring 56b. When the deflection pushes the pivot lever 56, the second oxygen supply valve 52 is also opened. This second oxygen supply valve delivers a constant flow of oxygen at a constant flow rate of about 1-2 liter of oxygen per minute when the connection to the oxygen source has been made. Typically, an additional 1 liter of oxygen per minute is fully sufficient for replacing the amount of CO.sub.2 in the exhaled air for an adult person when hyperventilating. The second oxygen supply valve 52 is also a constant flow rate nozzle valve with a calibrated bore that are available as standard nozzles and could be replaced if needed. However, this calibrated nozzle safeguards the efficient use of available oxygen for maximum length of usage and minimum consumption and is only open during hyperventilation.
[0071] FIG. 3c shows the same view as in FIG. 3b but during maximum activation of a manual activation knob 54. Here, only the stem 54a is shown on the activation knob shown in FIG. 1a. This state is only manually activated when the rebreather is to be started and pushing the activator knob to the bottom could fill the counter lung in a couple of seconds. This will set the starting conditions for the rebreather and the person to be treated will be fed by pure oxygen for maximum assistance and all CO.sub.2exhaled will be caught in the carbon dioxide scrubber. When the knob is pressed to the bottom, the additional deflection of the flexible membrane 55 is pushing the pivot lever 56 further around a pivot point 56a and against a pivot spring 56b. When the additional deflection pushes the pivot lever 56, the third oxygen supply valve 53 is also opened. This third oxygen supply valve delivers a constant flow of oxygen at a constant flow rate of about 10-100 liter, preferably 50-70 liter of oxygen per minute when the connection to the oxygen source has been made. The third oxygen supply valve 53 may be a simpler non-calibrated valve with a restriction gap capable of filling the system and an expanded counter lung in 1-3 seconds.
[0072] FIG. 3d shows the same view as in FIGS. 3a-3c but with no oxygen pressure applied when breathing takes place directly to atmosphere. As no pressure is established in the pressure chamber 5c are all oxygen supply valves idle. The shut-off valve 7a is opened by a return spring member allowing establishment of an alternative breathing passage to the ambient air chamber 7c.
[0073] FIG. 3e show an example of a constant flow rate nozzle valve that may be used as the first oxygen supply valve 51 and/or as the second oxygen supply valve 52. Here is also shown the pivot lever 56 (not used with nozzle 51) that may close the nozzle and may also have a sealing member 56s attached to the pivot lever. The nozzles are easily exchanged as they are mounted by threads and are manufactured in large series with calibrated flow capacity for any specific supply pressure.
[0074] FIGS. 4a-4c show the alternative breathing passage used in FIG. 3d with no oxygen pressure applied. A flat view of the valve seat member 8 is shown in FIG. 4a with the shut-off valve 7a and the contour of the ambient air chamber 7c shown in phantom lines. FIG. 4b shows the alternative breathing passage 7 through the ambient air chamber, which finally ends in a multiple of outlets 7b as shown in FIG. 4c.
[0075] Finally, a complete prototype of an embodiment of the invention is shown in FIG. 5. The rebreathing unit is here shown connected to an oxygen source O.sub.2 in form of a small pressure bottle. A standard pressure regulator 5d connects to the common valve housing X via a pressure hose 5a. The small tubular common valve housing X contains all the necessary valves, with a tubular carbon dioxide scrubber 3 connected orthogonally to the common valve housing. The tubular form is chosen to allow simple and steady handling of the rebreather with one hand.
