Abstract:
A respirator or anesthesia apparatus, for the artificial respiration of a patient, has a gas delivery device, at least one gas line for forming a breathing air line system, at least one gas mixing means with a mixed gas tank and at least two inlet openings with a shut-off member each for separately feeding at least two different gases to be mixed into the mixed gas tank and for subsequently feeding the mixed gas into the breathing air line system. The mixed gas tank is provided with at least two separate outlet openings for releasing the mixed gas from the mixed gas tank and for subsequently feeding it into the breathing air line system.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119 of European Patent Application EP 10 159 449.7 filed Apr. 9, 2010, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention pertains to a respirator (also known as a ventilator) or anesthesia apparatus for artificial respiration (also known as a ventilation) of a patient comprising a gas delivery means, at least one gas line for forming a breathing air line system such as a breathing air circulation system, at least one gas mixing means with a mixed gas tank and at least two inlet openings with a shut-off member each for separately feeding at least two different gases to be mixed into the mixed gas tank and for subsequently feeding the mixed gas into the breathing air line system and to a process of mixing at least two different gases in the respirator or anesthesia apparatus. 
       BACKGROUND OF THE INVENTION 
       [0003]    Artificial respiration of patients is necessary for various medical applications, e.g., during surgical procedures. Respirators are used for the artificial respiration of patients and may additionally also be used as anesthesia apparatuses for anesthesia with an anesthetic reflector and anesthetic dispensing unit. The expiration gas expired by the patient can be reused at least partly in some respirators, i.e., these devices represent a rebreathing system with a breathing air circulating system. A gas delivery means, which sends the breathing air to the patient during the inspiration, is present in the respirator with the breathing air circulating system. The gas delivery means is either switched off or is operated with a very low delivery flow only during and after the expiration. 
         [0004]    It is necessary, especially in anesthesia apparatuses, to feed a mixed gas to the inspiration gas. The mixed gas consists, for example, of oxygen and laughing gas. The gases to be mixed, namely, oxygen and laughing gas, are fed separately through shut-off valves to a mixed gas tank. The gases to be mixed, for example, oxygen or laughing gas, are introduced intermittently, such that only one shut-off valve is alternatingly opened. Thus, either, for example, only oxygen or only laughing gas is fed to the mixed gas tank. The mixed gas is released from the mixed gas tank continuously into a breathing air line system, especially into an inspiration gas line. If a gas to be mixed, for example, oxygen, is introduced into the mixed gas tank, the concentration of oxygen increases in the mixed gas tank, because only oxygen is introduced into the mixed gas tank. This also applies analogously if, for example, only laughing gas is introduced into the mixed gas tank. The mixed gas is released from the mixed gas tank continuously. The mixed gas removed from the mixed gas tank is fed to a breathing air line system of a respirator or anesthesia apparatus. Fluctuations in concentration will occur in the mixed gas tank and hence also in the mixed gas, which is fed to the breathing air line system, because of the intermittent dispensing. However, these fluctuations in concentration are not desirable, because the inspiration gas fed to the patient shall have the most uniform concentration possible. 
         [0005]    Local fluctuations in concentration may also occur within the mixed gas tank, so that additional fluctuations may likewise also occur in the concentration of the mixed gas fed to the breathing air line system as a result because of a non-optimal mixing of the mixed gas in the mixed gas tank. 
       SUMMARY OF THE INVENTION 
       [0006]    The object of the present invention is therefore to make available a respirator or anesthesia apparatus and a process for mixing at last two different gases in a respirator and anesthesia apparatus, in which fluctuations in the concentration of a mixed gas introduced into a breathing air line system can be compensated in a simple and reliable manner with a small technical effort. 
         [0007]    This object is accomplished with a respirator or anesthesia apparatus for the artificial respiration of a patient, comprising a gas delivery means, at least one gas line for forming a breathing air line system, especially a breathing air circulation system, at least one gas mixing means with a mixed gas tank and at least two inlet openings with a shut-off means each for the separate feed of at least two different gases to be mixed, especially oxygen, laughing gas, air, carbon dioxide or xenon, into the mixed gas tank and for the subsequent feeding of the mixed gas from the mixed gas tank into the breathing air line system, wherein the mixed gas tank is provided with at least two separate outlet openings for releasing the mixed gas from the mixed gas tank and for subsequently feeding it into the breathing air line system. Based on the release of the mixed gas from the mixed gas tank from at least two separate outlet openings, local fluctuations in concentration within the mixed gas tank can be compensated. 
         [0008]    In an additional embodiment, the at least two separate outlet openings in the mixed gas tank have a distance of at least 1 cm, 2 cm, 5 cm, 7 cm or 10 cm. 
         [0009]    In particular, a mixed gas line each is arranged at the at least two outlet openings, so that the mixed gas released from the at least two outlet openings flows through at least two mixed gas lines before being introduced into the breathing air line system. 
         [0010]    The at least two mixed gas lines open into a mixed gas collection line and the mixed gas collection line opens into the breathing air line system in another embodiment. Additional mixing of the gases of the mixed gas can take place in the mixed gas collection line. 
         [0011]    In an additional embodiment, the at least two mixed gas lines have different volumes for a pneumatic time delay between the at least two outlet openings and the breathing air line system and/or the mixed gas collection line. Fluctuations in the concentration of the gases to be mixed, which are fed to the mixed gas tank, occur within the mixed gas in the mixed gas tank. Only one gas to be mixed is fed now alternatingly to the mixed gas tank, so that fluctuations will occur in the concentration in the mixed gas in the mixed gas tank. Fluctuations in the concentrations of the different gases to be mixed, which are fed into the mixed gas tank, can be essentially compensated by a pneumatic time delay of the mixed gas taken from the at least two outlet openings. If, for example, a first gas to be mixed is present at a maximum concentration in the mixed gas tank at a first point in time and a second gas to be mixed is present in the mixed gas tank at a maximum concentration at a second point in time, the pneumatic time delay corresponds essentially to the time difference between the first and second points in time. The first gas to be mixed is present during the second point in time at a minimum concentration in the mixed gas tank. For example, the gas, which was removed from the mixed gas tank during the first point in time, is mixed with the mixed gas, which was removed from the mixed gas tank during the second point in time. As a result, mixed gas with a maximum concentration of the second gas to be mixed is mixed with mixed gas, which has a maximum concentration of the first gas to be mixed. As a result, the fluctuations occurring in the concentrations in the mixed gas tank can be essentially compensated in respect to the mixed gas fed to the breathing air line system based on the continuously increasing and decreasing fluctuations in the concentrations of the first and second gases to be mixed in the mixed gas tank. 
         [0012]    The volume of at least one mixed gas line is preferably larger than the volume of another mixed gas line by a factor of 1.1, 1.5, 2, 3 or 5. 
         [0013]    In one variant, the gases to be mixed, which are introduced into the mixed gas tank through the at least two inlet openings with a shut-off member each, can be introduced intermittently into the mixed gas tank. 
         [0014]    The shut-off members are preferably controlled such that only one shut-off member is alternatingly opened. 
         [0015]    In another embodiment, the difference of the volumes of at least two mixed gas lines corresponds essentially to a deviation of less than 70%, 50%, 30% or 20% of the volume of the mixed gas, which flows through the outlet opening arranged at the mixed gas line with the larger volume during an opening time of a shut-off member. 
         [0016]    In particular, at least one mixed gas line is arranged at least partially, especially as a buffer tank, within the mixed gas tank. The at least one mixed gas line with the larger volume can thus be made compact, because this is integrated as a result in the mixed gas tank as a buffer tank and the gas mixing means as a whole thus has a compact design. 
         [0017]    A process is provided according to the present invention for mixing at least two different gases in a respirator or anesthesia apparatus, especially a respirator or anesthesia apparatus described in this patent application, with the steps of introducing at least two gases to be mixed into a mixed gas tank, mixing of the at least two gases in the mixed gas tank, releasing the mixed gas from the mixed gas tank, introduction of the mixed gas into a breathing air line system, wherein the mixed gas is released from the mixed gas tank separately at least two different outlet openings. 
         [0018]    In another embodiment, the mixed gas released from an outlet opening is fed continuously with a time difference to the breathing air line system in relation to the mixed gas that is released from another outlet opening and is fed to the breathing air line system. 
         [0019]    The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawing and descriptive matter in which preferred embodiments of the invention are illustrated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0020]    In the drawing: 
           [0021]      FIG. 1  is a simplified view of a gas mixing means. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0022]    Referring to the drawings in particular,  FIG. 1  shows a gas mixing means  1  of an anesthesia apparatus, not shown. 
         [0023]    The anesthesia apparatus has a breathing air circulation system, so that expiration gas expired by the patient can be reused at least partly as an inspiration gas. The anesthesia apparatus is thus used for the artificial respiration and for the anesthesia of a patient, not shown. 
         [0024]    The inspiration gas fed to patients to be respirated is fed to the patient through an inspiration gas line  16 , which is designed as a part of a breathing air line system  14 , especially as a breathing air circulation system here. After flowing through the inspiration gas line  16  and a Y-piece  18 , the inspiration gas is fed to the patient through a mouthpiece  19 . The air expired by the patient is drawn off as expiration gas through an expiration gas line  17 . Nonreturn valves, not shown, are arranged at each of the inspiration gas as well as expiration gas lines  16 ,  17 . 
         [0025]    A mixed gas collection line  15  opens into the inspiration gas line  16 . Mixed gas consisting of different gases, for example, oxygen and laughing gas, is fed to the inspiration gas for the patient to be respirated through the mixed gas line  15 . The gas mixing means  1 , which makes the mixed gas available, which said mixed gas is introduced into the inspiration gas line  16  through the mixed gas collection line  15 , has a mixed gas tank  2  with a first inlet opening  7  and a second inlet opening  8 . A first shut-off member  3 , for example, a shut-off valve  4  or a gate valve, is arranged at the first inlet opening  7 , and a second shut-off member  5 , for example, a second shut-off valve  6  or a second gate valve, is arranged at the second inlet opening  8 . A first gas to be mixed, e.g., oxygen, is introduced into the mixed gas tank  2  through a first feed line  20 , and a second gas to be mixed, e.g., laughing gas, is introduced into the mixed gas tank  2  through a second feed line  21 . The first shut-off member  3  and the second shut-off member  5  are opened now alternatingly, so that only oxygen flows into the mixed gas tank  2  through the first feed line  7  during a first time period and only laughing gas flows into the mixed gas tank  2  through the second inlet opening  8  during a second time period. The two shut-off members  3 ,  5  are thus not opened simultaneously. 
         [0026]    The mixed gas tank  2  has a first outlet opening  9  and a second outlet opening  10 . The gas mixed in the mixed gas tank is removed from the mixed gas tank  2  through the first and second outlet openings  9 ,  10 . The two outlet openings  9 ,  10  are spaced apart a greater distance, for example, in the range of 1 cm to 10 cm. The mixed gas removed from the first outlet opening  9  is fed through a first mixed gas line  11  to the mixed gas collection line  15  and the mixed gas removed from the second outlet opening  10  is likewise sent to the mixed gas collection line through a second mixed gas line  12 . The second mixed gas line  12  is partly also integrated in the mixed gas tank  2  and has a substantially larger volume than the first mixed gas line  11 . The second mixed gas line  12  in the mixed gas tank  2  is designed here as a buffer tank  13 , at which the second outlet opening  10  is also present. Due to the separate removal of the mixed gas from the mixed gas tank through two different outlet openings  9 ,  10 , local fluctuations in the oxygen and laughing gas concentrations within the mixed gas tank  2  can advantageously be essentially compensated. 
         [0027]    Due to the intermittent and alternating introduction of the two gases to be mixed into the mixed gas tank  1 , fluctuations will occur in the concentrations of the two gases oxygen and laughing gas in the mixed gas. If, for example, only oxygen is introduced into the mixed gas tank  2  through the first shut-off member  3  and the first inlet opening  7 , the concentration of oxygen increases in the mixed gas tank  2  and the concentration of laughing gas will also decrease as a result in the mixed gas tank  2 . The mixed gas is now released continuously from the mixed gas tank  2  through the two outlet openings  9 ,  10  and introduced continuously into the inspiration gas line  16 . The volume of the second mixed gas line  12  with the buffer tank  13  is substantially larger than the volume of the first mixed gas line  11 . This leads to a pneumatic time delay of the mixed gas, which flows into the mixed gas collection line  15  through the first and second mixed gas lines  11 ,  12 . The difference of the volumes between the first and second mixed gas lines  11 ,  12  is designed such that the mixed gas sent through the first mixed gas line  11  to the mixed gas collection line  15  has a maximum oxygen concentration and the mixed gas introduced at the same point in time into the mixed gas collection line  15  through the second mixed gas line  12  has a maximum laughing gas concentration. Due to the larger volume of the second mixed gas line  12 , the mixed gas, which is removed from the mixed gas tank  2  through the second mixed gas line  12  and is introduced into the mixed gas collection line  12 , thus flows into the mixed gas collection line  15  with a time delay in relation to the mixed gas that is introduced into the mixed gas collection line  15  through the first mixed gas line  11 . At a maximum oxygen concentration in the mixed gas tank  2 , a minimum concentration of laughing gas is present in the mixed gas tank  2  and vice versa. The concentration of oxygen in the mixed gas tank  2  increases during the period during which only oxygen is fed exclusively into the mixed gas tank  2 , and the concentration of laughing gas analogously decreases in the mixed gas tank  2 . The concentration of laughing gas analogously increases continuously in the mixed gas tank  2  and the concentration of oxygen decreases in the mixed gas tank  2  during the period during which laughing gas is exclusively introduced into the mixed gas tank  2 . If, for example, the oxygen concentration decreases and the laughing gas concentration increases in the mixed gas tank  2 , this leads, because of the pneumatic time delay at the beginning of the mixed gas collection line  15 , to a simultaneous increase in the concentration of oxygen in the mixed gas in the second mixed gas line  12 , i.e., at the end of the second mixed gas line  12  at the mixed gas collection line  15  and an increase of the concentration of laughing gas in the mixed gas at the end of the first mixed gas line  11  at the mixed gas collection line  15 . This is also true vice versa. The concentration fluctuations of the mixed gas in the mixed gas tank  2  due to the alternating and intermittent admission of the two gases to be mixed can thus be compensated in the mixed gas tank  2  continuously essentially in a simple manner. 
         [0028]    On the whole, considerable advantages are associated with the respirator or anesthesia apparatus according to the present invention. The separate release of the mixed gas from the at least two separate outlet openings  9 ,  10  makes it possible to essentially compensate concentration fluctuations within the mixed gas tank  2  due to an inhomogeneous mixing of the mixed gas. The fluctuations in the concentration of the gases to be mixed in the mixed gas tank  2  over time can be essentially compensated by the pneumatic time delay in the two mixed gas lines  11 ,  12 . This makes possible an essentially constant concentration of the mixed gas fed to the inspiration gas line  16 . 
         [0029]    While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. 
       LIST OF REFERENCE NUMBERS 
       [0000]    
       
           1 . Gas mixing means 
           2 . Mixed gas tank 
           3 . First shut-off member 
           4 . First shut-off valve 
           5 . Second shut-off member 
           6 . Second shut-off valve 
           7 . First inlet opening 
           8 . Second inlet opening 
           9 . First outlet opening 
           10 . Second outlet opening 
           11 . First mixed gas line 
           12 . Second mixed gas line 
           13 . Buffer tank 
           14 . Breathing air line system 
           15 . Mixed gas collection line 
           16 . Inspiration gas line 
           17 . Expiration gas line 
           18 . Y-piece 
           19 . Mouthpiece 
           20 . First feed line for the first gas to be mixed 
           21 . Second feed line for the second gas to be mixed