Abstract:
An apparatus and method for supplying a breathing gas for a respiration. The apparatus includes a reciprocating unit configured to receive an inspiration gas flow and adapted to control respiratory movements. The apparatus also includes a gas mixer for supplying a fresh gas flow. The apparatus also includes a breathing circuit configured to conduct an expiration gas flow to the reciprocating unit and to conduct the fresh gas flow from the gas mixer for the respiration and to conduct the gas flow from the reciprocating unit for an inspiration, the breathing circuit comprising a CO2 remover configured to remove carbon dioxide from the gas. The apparatus also includes a first bypass passage configured to permit bypassing the reciprocating unit and connecting the breathing circuit to the inspiration gas flow upstream from the reciprocating unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not Applicable 
       REFERENCE TO A SEQUENCE LISTING, A TABLE, OR COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON COMPACT DISC 
       [0004]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    This disclosure relates generally an arrangement and method for supplying a breathing gas for a respiration. 
         [0007]    2. Description of Related Art 
         [0008]    Hospital efficiency requirements get more demanding, more patients have to be taken through a surgery process in a shorter time and less costs. In spite of all, a patient safety is a primary requirement. Anesthesia machines are used for anesthetizing and ventilating patients in hospital operating rooms, intensive care units or other patient care places. 
         [0009]    A patient breathing circuit can be a re-breathing circuit or an open circuit. The re-breathing circuit with a CO2 absorber is used when volatile anesthetic or NO2, or both, exist in anesthesia. Instead the open circuit is used with an intravenous (IV) anesthesia. 
         [0010]    Inhalation anesthesia is thus delivered using the re-breathing circuit comprising an inspiratory limb through which a patient gets an inspired breathing gas from a ventilator, an expiratory limb carrying an exhaled gas back to the ventilator, a Y-piece connecting the inspiratory and expiratory limbs to a further patient limb providing a gas communication pathway to patient lungs. An expired gas comprises a lot of expensive and environment-hostile anesthesia gases. The re-breathing circuit is used to return the expired gas to next inspiration. Before doing this, the gas must be cleared out from the carbon dioxide extracted from the patient lungs as waste product of a patient metabolism. The clearance is done in a CO2 absorber. 
         [0011]    Traditional anesthesia ventilator comprises a bellows-in-bottle, which separates a ventilator drive gas from the circulating breathing gas. For the inspiration, outside of the bellows is pressurized with ventilator drive gas. This squeezes the bellows forcing the breathing gas within the bellows to flow towards the patient lungs. During the expiration, the drive gas pressure is released and the gas pressurized in the patient lungs flows out filling the bellows. Breathing gas is supplied to the re-breathing circuit as continuous flow using a fresh gas line. Once the bellows is filled, further gas flow to the circuit from the patient and the fresh gas line increases the circuit pressure that opens an over-pressure bleed valve for a removal of this further gas to a scavenging system. 
         [0012]    In a new re-breathing circuit drive gas—a breathing gas separation is done using a long gas channel where a gas column is moving back-and-forth during the course of the inspiration and the expiration. The re-breathing circuit saves anesthesia gases, and hence lowers the hospitals anesthesia expenses, and decreases environment effects. The CO2 absorption and the re-breathing circuit are not needed when an anesthetic is not breathable, but e.g. an intravenous-drug. The intravenous-anesthesia is gaining popularity and optimal solution is needed there too. The open breathing circuit is more simple solution than the re-breathing circuit, but it cannot be used with the inhalation anesthesia. It is cheaper and easier, to utilize the open breathing circuit in the IV-anesthesia. But sometimes the IV-anesthesia needs to exchange to inhalation anesthesia during the case. In this case the re-breathing circuit is needed because of the anesthesia gases. In state-of the art devices such switchover is not possible and therefore IV anesthesia is delivered using non-optimal equipment. Current anesthesia solution is the re-breathing circuit whereas the open circuit is used in an intensive care ventilation. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    The above-mentioned shortcomings, disadvantages and problems are addressed herein which will be understood by reading and understanding the following specification. 
         [0014]    In an embodiment, an arrangement for supplying a breathing gas for a respiration includes a reciprocating unit receiving an inspiration gas flow adapted to control respiratory movements and a gas mixer for supplying a fresh gas flow. The arrangement for supplying a breathing gas for a respiration also includes a breathing circuit for conducting an expiration gas flow to the reciprocating unit and for conducting the fresh gas flow from the gas mixer for the respiration and for conducting the gas flow from the reciprocating unit for an inspiration, the breathing circuit comprising a CO2 remover for removing carbon dioxide from the gas. The arrangement for supplying a breathing gas for a respiration further includes a first bypass passage bypassing the reciprocating unit and connecting the breathing circuit to the inspiration gas flow upstream the reciprocating unit. 
         [0015]    In another embodiment, a method for supplying a breathing gas for a respiration includes supplying an inspiration gas flow to a reciprocating unit to control respiratory movements and supplying a fresh gas flow to a breathing circuit. The method for supplying a breathing gas for a respiration also includes conducting along a breathing circuit an expiration gas flow to the reciprocating unit and the fresh gas flow for the respiration and a gas flow from the reciprocating unit for inspiration, and removing carbon dioxide from the gas flowing in the breathing circuit. The method for supplying a breathing gas for a respiration further includes an option to supply the inspiration gas flow to the breathing circuit bypassing the reciprocating unit. 
         [0016]    In yet another embodiment an arrangement for supplying a breathing gas for a respiration includes a ventilator having a reciprocating unit receiving an inspiration gas flow along a first canal and discharging an expiration gas flow along a second canal, the reciprocating unit being adapted to control respiratory movements. The arrangement for supplying a breathing gas for a respiration also includes a gas mixer for supplying a fresh gas flow for a respiration and a breathing circuit for conducting an expiration gas flow to the ventilator and for conducting the fresh gas flow from the gas mixer for the respiration and for conducting the gas flow from the ventilator for the inspiration, the breathing circuit comprising a CO2 remover for removing carbon dioxide from the gas. The arrangement for supplying a breathing gas for a respiration further includes a first bypass passage connecting the first canal and the breathing circuit and further comprising a second bypass passage connecting the breathing circuit and the second canal wherein both the first bypass passage and the second bypass passage are adapted to bypass the reciprocating unit. 
         [0017]    Various other features, objects, and advantages of the invention will be made apparent to those skilled in art from the accompanying drawings and detailed description thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0018]      FIG. 1  is a schematic view of a system in accordance with an embodiment; 
           [0019]      FIG. 2  is a schematic view of a system in accordance with another embodiment; 
           [0020]      FIG. 3  shows a selector valve in a first position useful for embodiments shown in  FIG. 1  or  2 ; 
           [0021]      FIG. 4  shows the selector valve of  FIG. 3  in a second position; 
           [0022]      FIG. 5  shows another selector valve in a first position useful for embodiments shown in  FIG. 1  or  2 ; and 
           [0023]      FIG. 6  shows the selector valve of  FIG. 5  in a second position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0024]    Specific embodiments are explained in the following detailed description making a reference to accompanying drawings. These detailed embodiments can naturally be modified and should not limit the scope of the invention as set fort in the claims. 
         [0025]      FIGS. 1 and 2  shows an arrangement for exchanging between a re-breathing circuit and open circuit modes in an anesthesia system. The anesthesia system comprises a ventilator  1 , a breathing circuit  2  and a fresh gas mixer  3 . A subject  4  is connected to the breathing circuit  2  by means of an endotracheal tube  28 . 
         [0026]    In  FIG. 1  the ventilator  1  is connected to a gas supply  5 , which is typically pressurized air or sometimes also oxygen. The ventilator  1  comprises a reciprocating unit  6  for compressing gas towards lungs of the subject to facilitate the inspiration, a flow control valve  7  to control the inspired gas flow from the gas supply  5  along a first canal  8  towards the reciprocating unit  6 . Further the ventilator  1  comprises an expiration valve  9  used to control the expired gas flow rate through a second canal  10  releasing the gas of the ventilator  1  or the reciprocating unit  6  when the subject  4  is expiring. The ventilator  1  can also comprise a scavenging valve  11  allowing an extra expired gas of the subject  4  to leave the breathing circuit  2 . The ventilator  1  may be equipped with a gas supply selection (not shown) that can be used to switch the ventilator gas flow for the inspiration either manually or automatically e.g. in case the used gas gets un-pressurized. The reciprocating unit  6  shown in  FIG. 1  comprises a bottle  14  and a bellows  15  within the bottle  14  for controlling respiratory movements of the subject&#39;s lungs. 
         [0027]    When ventilating the subject, the expiration valve  9  is closed and the flow control valve  7  is opened for the inspiration flow. This flow fills the bottle  14  making the bellows  15  to push down pushing the gas within the bellows further towards the subject  4 . During the expiration the flow control valve  7  is closed and the expiration valve  9  is opened to control the expiration flow and pressure. The gas pressurized in the bottle  14  is released allowing the gas from lungs to fill the bellows  15  up. When the bellows  15  is filled, it hits the top of the bottle  14 , and the further gas flow into the system increases the pressure within the bellows  15 . When this pressure exceeds the bottle pressure, the scavenging valve  11  will open allowing the further gas flow to scavenging system. 
         [0028]    The ventilator  1  is connected to the breathing circuit  2  such as a re-breathing circuit by means of the ventilator tube  17  for both inspired and expired gas flows. The breathing circuit  2  comprises an inspiration tube  18  for inspired gas, an expiration tube  19  for expired gas, a CO2 remover  20  such as CO2 absorber to remove or absorb carbon dioxide from the exhaled gas coming from the subject  4 , a first one-way valve  21  for inspired gas in the inspiration tube  18 , a second one-way valve  22  for expired gas in the expiration tube  19 , a branching unit  23  such as a Y-piece having at least three limbs, one of them being an inhalation limb  24  for inspired gas, a second one being an expiration limb  25  for expired gas, a third one being a combined inspiration and expiration limb  26  for both inspired and expired gases. The inhalation limb  24  is connectable to the inspiration tube  18  and the expiration limb  25  is connectable to the expiration tube  19 . The combined inspiration and expiration limb  26  of the branching unit  23  may be connectable by means of a patient tube  27  to the endotracheal tube  28  allowing the gas exchange with airways of the subject  4 . 
         [0029]    The inspiration gas flows from the reciprocating unit  6  through the ventilator tube  17 , the CO2 remover  20 , the first one-way valve  21  and the inspiration tube  18  of the patient circuit  2  to the branching unit  23  and further through the patient tube  27  and the endotracheal tube  28  to the lungs of the subject  4 . The second one-way valve  22  on the expiratory tube  19  guides the gas flow direction to the inspiration tube  18  by closing the flow from the ventilator tube  17  through the expiration tube  19 . Increasing the gas volume within the lungs increases the lung pressure due to the lung compliance. Once the inspiration stops and the expiration valve  9  opens relieving the bottle  14  pressure, the lung compliance pushes the alveolar gas through the endotracheal tube  28  and the patient tube  27  to the branching unit  23  and further through the expiration tube  19  and the ventilator tube  17  to fill the bellows  15 . 
         [0030]    The gas mixer  3  for delivering a fresh gas is connected to the breathing circuit  2  by means of a channel  35 . The gas mixer  3  is used to offer the patient breathing gas. One or more gas supplies  5 ,  30 ,  31  is connected to the gas mixer  3 . The gas supply  5  is for the air as described above, the gas supply  30  is for oxygen and the gas supply  31  is for nitrous oxide. The gas mixer comprises a valve  32  to select either the gas supply  31  for nitrous oxide or the gas supply  5  for air, a flow regulating valve  33  for regulating either nitrous oxide or air flow, a flow regulating valve  34  for regulating oxygen flow and an anesthetic agent supply  37  such as a vaporizer for supplying anesthetic agent to anesthetize the subject  4 . The anesthetic agent supply  37  adds the inhalation agent into the gas mixture selected. Alternatively the anesthesia agent can be injected directly into the breathing circuit in a liquid form when it will be vaporized to the gas in the circuit or as a vapor. 
         [0031]    The breathing circuit  2  may still be completed with a gas analyzer  39 , which can be of a side-stream type as presented or a mainstream type. Side-stream analyzers take a sample gas flow for analysis from the breathing circuit  2 . The gas analyzer  39 , which is the mainstream type is analyzing the flowing gas directly in the breathing circuit  2  or in the patient tube  27 . 
         [0032]    The re-breathing circuit mode is used especially when delivering breathing gas with anesthetic agent or NO2 to the subject as described above, but when delivering a breathing gas without anesthetic agent or NO2 it is advantageous to exploit an open circuit mode in which case only partly same elements are exploited as used with the re-breathing circuit mode. Especially the CO2 remover  20  is not needed in the open circuit mode whereupon it can be bypassed when delivering the inspired gas flow from the gas supply  5  to the breathing circuit  2 . A remarkable advantage is that a content of the CO2 remover  20  can be saved only for the re-breathing circuit mode use to remove CO2 exhaled by the subject. Also an inhaling resistance can be decreased by bypassing the CO2 remover  20 . Further the inhaling resistance can be decreased by bypassing the reciprocating unit  6  in the open circuit mode. 
         [0033]    In  FIG. 1  a selector valve  50  for the inspiration is connected to the first canal  8  of a ventilator  1  to guide the inspired gas flow from the gas supply  5  either through a first bypass passage  51  to the breathing circuit  2  downstream the CO2 remover  20  and the first one-way valve  21  and advantageously to the inspiration tube  18  bypassing both the CO2 remover  20  and the first one-way valve  21  or to the reciprocating unit  6  being in flow connection with the breathing circuit upstream the CO2 remover  20  whereupon the inspired gas flow guides respiratory movements of the subject through the CO2 remover  20 , the first one-way valve  21  and the inspiration tube  18 . 
         [0034]    To guide the inspired gas flow the selector valve  50  for the inspiration in flow connection with the first bypass passage  51  is adapted to stop the inspiration gas flow either to the first bypass passage  51  in case the re-breathing circuit mode is selected and to open the inspiration gas flow to the reciprocating unit  6  or alternatively the selector valve  50  for the inspiration is adapted to stop the inspiration gas flow to the reciprocating unit  6  in case the open circuit mode is selected and to open the inspiration gas flow to the first bypass passage  51 . The first bypass passage  51  can be connected to the breathing circuit  2  upstream or downstream the breathing circuit connection of the channel  35 , but preferably the first bypass passage  51  is connected between the inhalation limb  24  of the branching unit  23  and the first one-way valve  21 . 
         [0035]    It is advantageous to connect one end of a second bypass passage  53  to a breathing circuit  2  upstream the second one-way valve  22 , preferably between the second one-way valve  22  and the expiration limb  25  of the branching unit  23 . Another end of the second bypass passage  53  is connected to discharge the expiration gas flow to the second canal  10  between the reciprocating unit and the expiration valve  9 . In flow connection with the second bypass passage  53  there is arranged a selector valve  52  for an expiration in the ventilator  1  to guide the expired gas flow in the expiration tube  19  of the breathing circuit  2  either through the second bypass passage  53  to between the reciprocating unit  6  and one of the expiration valve  9  and the scavenging valve  11  allowing an extra expired gas of the subject  4  to leave the breathing circuit  2  thus bypassing the reciprocating unit  6  making an expiration of the subject easier in the open circuit mode or through the second one-way valve  22  to the reciprocating unit  6  in the re-breathing circuit mode. 
         [0036]    To guide the expired gas flow the selector valve  52  for the expiration is adapted to stop the expired gas flow either to the second bypass passage  53  in case the re-breathing circuit mode is selected and to open the expired gas flow to the reciprocating unit  6  or alternatively the selector valve  52  for the expiration is adapted to stop the expired gas flow to the reciprocating unit  6  in case the open circuit mode is selected and to open the expired gas flow through the second bypass passage  53  to between the reciprocating unit  6  and one of the expiration valve  9  and the scavenging valve  11 . However, it is important to notice that this second bypass passage  53  is advantageous, but not absolutely necessary, because the most important thing is to arrange the first bypass passage  51  as explained hereinbefore. Thus the expiration gas flow can go towards the reciprocating unit  6  besides in case of the re-breathing circuit mode but also in case of the open circuit mode. The second bypass passage  53  for the expiration gas can be connected in the breathing circuit end also downstream the second one-way valve  22 , but this connection would make the arrangement more complicated requiring extra valves to guide flows into the desired direction. 
         [0037]      FIG. 2  presents another embodiment for the reciprocating unit  6  useful in the anesthesia system. The reciprocating unit  6  comprises a long gas flow channel  41  functions differently from the one shown in  FIG. 1 . The channel  41  is part of a continuous flow pathway between said gas supply  5  and said breathing circuit  2 . The separation of the ventilator gas and the breathing gas is made with a gas gradient reciprocating in the gas flow channel  41 . In this the receiving information indicative of the measured gas flows the gas supply  5  pushes the inspiration gas towards the ventilator  1  and through the flow control valve  7  to control the inspiration gas flow and to the channel  41 . This will push the prevailing gas from the channel  41  further to the inspiration tube  18  of the breathing circuit  2  and further to the subject  4 . During the expiration the expiration valve  9  is opened releasing the pressure of the channel  41  and the breathing circuit  2 . The lung compliance drives the gas out from the lungs through expiration tube  19  to the channel  41 . This pushes the gas loaded into the ventilator end of the channel  41  during the inspiration out from the channel  41  through the expiration valve  9  of the ventilator  1 . Would the fresh gas stream into the breathing circuit  2  exceed the one removed, the excess flows through the channel  41  of the reciprocating unit  6  and gets also scavenged through the expiration valve  9 . 
         [0038]    Also in  FIG. 2  the selector valve  50  for the inspiration is arranged to guide the inspired gas flow from the gas supply  5  either in the open circuit mode through the first bypass passage  51  to the breathing circuit  2  downstream the CO2 remover  20  and the first one-way valve  21  to the inspiration tube  18  bypassing both the CO2 remover  20  and the first one-way valve  21  or in the re-breathing circuit mode to the reciprocating unit  6  being in flow contact with the breathing circuit upstream the CO2 remover  20  whereupon the inspired gas flow guides respiratory movements of the subject through the CO2 remover  20 , the first one-way valve  21  and the inspiration tube  18 . The selector valve  50  is arranged both in  FIGS. 1 and 2  upstream the reciprocating unit  6  in which case it may be part of the ventilator  1 . 
         [0039]    To guide the inspired gas flow in  FIG. 1  the selector valve  50  for the inspiration is adapted to stop the inspired gas flow either to the first bypass passage  51  in case the re-breathing circuit mode is selected and to open the inspired gas flow to the reciprocating unit  6  or alternatively the selector valve  50  for the inspiration is adapted to stop the inspired gas flow to the reciprocating unit  6  in case the open circuit mode is selected and to open the inspired gas flow to the first bypass passage  51 . The first bypass passage  51  can be connected to the breathing circuit  2  upstream or downstream a breathing circuit connection of the channel  35 , but preferably the first bypass passage  51  is connected between the inhalation limb  24  of the branching unit  23  and the first one-way valve  21 . 
         [0040]    In  FIG. 2 , just as with  FIG. 1  embodiment, the selector valve  52  for the expiration with the second bypass passage  53  is arranged to make the expiration of the subject easier. The selector valve  52  for the expiration connecting an end of the second bypass passage  53  to the breathing circuit  2  is arranged between the second one-way valve  22  and the expiration limb  25  of the branching unit  23  to guide the expired gas flow in the expiration tube  19  of the breathing circuit  2  either through the second bypass passage  53  to the second canal  10  downstream the reciprocating unit  6  which may be between the reciprocating unit  6  and the expiration valve  9  allowing an extra expired gas of the subject  4  to leave the breathing circuit  2  thus bypassing the reciprocating unit  6  in the open circuit mode or through the second one-way valve  22  towards the reciprocating unit  6  in the re-breathing circuit mode. 
         [0041]    To guide the expired gas flow the selector valve  52  for the expiration is adapted to stop the expired gas flow either to the second bypass passage  53  in case the re-breathing circuit mode is selected and to open the expired gas flow towards the reciprocating unit  6  or alternatively the selector valve  52  for the expiration is adapted to stop the expired gas flow towards the reciprocating unit  6  in case the open circuit mode is selected and to open the expired gas flow through the second bypass passage  53  to between the reciprocating unit  6  and the expiration valve  9 . Just as with  FIG. 1  also with  FIG. 2  it is important to notice that this second bypass passage  53  is advantageous but not absolutely necessary, because the most important thing is to arrange the first bypass passage  51  as explained hereinbefore. Thus the expiration gas flow can go towards the reciprocating unit  6  besides in case of the re-breathing mode but also in case of the open circuit mode. The selector valve  52  for the expiration as well as the second bypass passage end in the breathing circuit  2  can also locate downstream the second one-way valve  22 , but this arrangement would make the arrangement more complicated requiring extra valves to guide flows into the desired direction. 
         [0042]    Otherwise the embodiment of  FIG. 2  is used on the same principles as described above in connection to  FIG. 1 . The gas mixer  3  can be identical to  FIG. 1 . 
         [0043]      FIGS. 3 ,  4 ,  5  and  6  shows a solution which can be exploited in  FIGS. 1 and 2  to replace the selector valve  50  for the inspiration and the selector valve  52  for the expiration by a single combined selector valve  54  for both the inspiration and expiration being in flow connection with the first bypass passage  51  and the second bypass passage  53 . According to an option this selector valve  54  is arranged to supply the inspiration gas flow to the breathing circuit  2  bypassing the reciprocating unit  6  and also an option to arrange simultaneously the expiration gas flow of the breathing circuit to be discharged bypassing the reciprocating unit. The selector valve  54  for both the inspiration and expiration in a first position enables isolation and detaching the CO2 remover and the reciprocating unit  6  when the open circuit mode is selected and vice versa in a second position the combined selector valve  54  enables connecting the CO2 remover and the reciprocating unit  6  when the re-breathing circuit mode is selected. 
         [0044]    In  FIGS. 3 and 4  the selector valve  54  for both the inspiration and expiration is a rotary valve, which can be rotated from the first position to the second position. In  FIG. 3  the open circuit mode is selected where the selector valve  54  for both the inspiration and expiration is in the first position and thus stopping the inspired gas flow from going through the reciprocating unit  6  and the CO2 remover  20  and the expired gas flow from going towards the reciprocating unit  6 , but bypassing them. The inspiration gas flow is coming along the first canal  8  to the selector valve  54  for both the inspiration and expiration, which in this first position directs the flow through the first bypass passage  51  to the inspiration tube  18  and the branching unit  23  to the subject  4  bypassing both the reciprocating unit  6  and the CO2 remover  20 . When expiring the expired gas is led through the branching unit  23  and the expiration tube  19  to the selector valve  54  for both the inspiration and expiration which in the first position directs the expired gas through the second bypass passage  53  to the second canal  10  for the expired gas bypassing the reciprocating unit  6 . 
         [0045]      FIG. 4  representing a situation where the re-breathing circuit mode is selected the selector valve  54  for both the inspiration and expiration is in the second position directing the inspiration gas flow to the reciprocating unit  6  whereupon the gas flows in the breathing circuit through the CO2 remover  20 , the first one-way valve  21 , the inspiration tube  18  and the branching unit  23  to the subject  4 . During the expiration phase the expired gas is flowing through the branching unit  23 , the expiration tube  19  and the second one-way valve  22  towards the reciprocating unit  6  to discharge the expired gas in the second canal  10 . 
         [0046]    The selector valve  54  for both the inspiration and expiration can be also a slide valve as shown in  FIGS. 5 and 6  having a chance to select between the first position and the second position. A slide  55  can slide up and down to find either the first position or the second position. In the first position as shown in  FIG. 5  the slide  55  closes the inspiration gas flow towards the reciprocating unit  6  and through the CO2 remover  20 . Also the expired gas flow towards the reciprocating unit  6  is closed. The inspired gas flow is coming along the first canal  8  to the selector valve  54  for both the inspiration and expiration, which in this first position directs the flow through the first bypass passage  51  to the inspiration tube  18  and further to the branching unit  23  and to the subject  4  bypassing both the reciprocating unit  6  and the CO2 remover  20 . When expiring the expired gas is conducted through the branching unit  23  and the expiration tube  19  to the selector valve  54  for both the inspiration and expiration, which in the first position directs the expired gas through the second bypass passage  53  to the second canal  10  for the expired gas bypassing the reciprocating unit  6 . 
         [0047]    The re-breathing circuit mode is selected in  FIG. 6  where the theselector valve  54  for the inspiration and expiration is in the second position directing the inspiration gas flow towards the reciprocating unit  6  and through the CO2 remover  20  to the first one-way valve  21  guiding the inspired gas flow through the inspiration tube  18  and the branching unit  23  to the subject  4 . During the expiration phase the expired gas is flowing from the subject  4  through the branching unit  23 , the expiration tube  19 , the second one-way valve  22  towards the reciprocating unit  6  to discharge the expired gas through the second canal  10 . 
         [0048]    Isolation and detaching the CO2 remover  20  and the reciprocating unit  6 , enables the open circuit mode use also in situations when the CO2 remover  20  and the reciprocating unit  6  are not available or needed. On this account solution of two isolated breathing circuit systems in the same device increases patient safety and efficiency of utilization. For example, in situations when the subject needs the respiratory care after the anesthesia, the CO2 remover  20  and the reciprocating unit  6  can be removed and maintain for next anesthesia, if the open circuit mode is used, and after the maintenance it can again be attached to the system without contamination. 
         [0049]    The removable CO2 remover  20  and reciprocating unit  6  allow a development of a block solution for the re-breath circuit, and this way allows practicable disposableness. It also facilitates regular cleaning and maintenance of the system, even when the ventilator  1  is in use and when a single selector valve  54  for both the inspiration and expiration such as the rotary or slide valve is in use. The re-breathing circuit is connected in the system by three connections as shown in  FIGS. 3-6 , which are close to each other making the disconnection of the CO2 remover  20  and the reciprocating unit  6  easy, quick and safe. 
         [0050]    The isolated re-breathing system decreases a demand of the reciprocating unit  6  and the CO2 remover  20  when the open breathing system is used. It also decreases a need for cleaning and maintenance of the re-breathing system. This cuts down hospital expenses, because those elements need to replace for new ones less frequently. 
         [0051]    Changing between, the open and re-breath circuit system, and vice versa, is fast and is assumed to be safe, and it allows optimal breathing circuit use for every anesthesia type. 
         [0052]    The written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.