Abstract:
A device for adsorbing and desorbing anesthetic shall be improved in respect of the anesthetic supply. A sampling device ( 16 ) for removing a gas volume of the breathing gas and an anesthetic dispenser ( 18 ) are connected to the breathing gas line ( 8 ) between the adsorption filter ( 9 ) and the patient ( 10 ) in such a way that the gas volume removed and the gas volume supplied are compensated.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2007 048 891.4 filed Oct. 11, 2007, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention pertains to a device for supplying a patient with breathing gas with a filter device for the adsorption and desorption of anesthetic and with a breathing gas line between the filter device and the patient. 
       BACKGROUND OF THE INVENTION 
       [0003]    Devices for recycling expired anesthetic are known from the state of the art and are based on the principle that expired gas is sent over a filter, which adsorbs expired anesthetic and fresh breathing gas is sent subsequently over the filter during a desorption phase in order to enrich it with previously stored anesthetic. 
         [0004]    A device of this class is known from U.S. Pat. No. 6,206,002 B1. A patient is connected via a breathing gas line to a filter device for adsorbing and desorbing anesthetic. Fresh breathing gas arrives now at the patient from a breathing gas source via the filter device and a breathing gas line. The breathing gas is mixed with anesthetic by means of an anesthetic source in the vicinity of the patient. The anesthetic breathed out by the patient is adsorbed in the filter device during the phase of expiration and mixed again with the gas to be breathed in during the next inspiration stroke. The anesthetic consumed by the patient during stationary operation and the anesthetic not adsorbed by the filter device during the phase of expiration are replaced with the anesthetic source. Anesthetic is mixed with the breathing gas in the liquid form during the phase of expiration, and only special anesthetic dispensing devices can therefore be used. The dispensing of liquid anesthetic in the vicinity of the patient requires a great effort in terms of monitoring of the release of concentration. 
         [0005]    EP 1 440 704 B1 discloses a device for the recycling of anesthetic, in which an adsorption filter is moved between two gas channels in order to alternatingly expose a same section of the filter to the interior of each channel. Since separate channels are present in this device for the gas to be breathed in and the expired gas, the dead space volume decreases to the volume of the filter sections that are staggered between the gas channels. However, more specific data on how the anesthetic is fed to the patient cannot be found in the document. It is also disadvantageous in the prior-art device that a rinsing gas is needed during a rapid phase of termination in order to rinse through the adsorption beds and to remove the anesthetic. 
       SUMMARY OF THE INVENTION 
       [0006]    The basic object of the present invention is to improve a device of the type mentioned such that the supply of anesthetic is made possible with a plurality of anesthetic dispensers. 
         [0007]    According to the invention, a device is provided for supplying a patient with breathing gas, the device comprises a filter device for the adsorption and desorption of anesthetic. A breathing gas line is provided between the filter device and the patient. A sampling device is connected to the breathing gas line for sampling breathing gas. An anesthetic dispensing device is connected to the breathing gas line to provide a compensation between a gas volume removed and a gas volume fed in the device. 
         [0008]    The sampling device may comprise an anesthetic measuring device. The gas sampling device may also comprise a breathing gas source for the anesthetic dispensing device. 
         [0009]    A gas analysis port may be provided for gas sampling, for connecting the sampling device. The gas analysis port is arranged between a connecting branch to an anesthetic supply of the anesthetic dispensing device and the patient. The gas analysis port may also be provided between a connecting branch to an anesthetic supply of the anesthetic dispensing device and the filter device. 
         [0010]    The breathing gas line may comprise separate line sections for the gas to be inspired and gas to be expired. 
         [0011]    Provisions are made according to the present invention for breathing gas enriched with anesthetic vapor to be introduced into the breathing gas line between the filter device and the patient and for a gas volume to be drawn off with a sampling device for breathing gas in such a way that it corresponds to the breathing gas volume fed with the anesthetic dispenser. Thus, the inspired volume is not changed in terms of the volume balance, because there is a corresponding gas volume, which is again drawn off with the sampling device in the form of a sampling pump, against the breathing gas volume enriched with anesthetic, which is additionally fed into the breathing gas line. A plurality of commercially available dispensing systems can be used due to the use of anesthetic dispensers, which need breathing gas for dispensing anesthetic. These include all the anesthetic evaporators, which operate according to the bypass principle and in which a part of the breathing gas is branched off from a bypass line and sent through an evaporating chamber for enrichment with anesthetic vapor. Furthermore, dispensing systems for highly volatile anesthetics, such as desflurane, which are based on a differential pressure regulation of two gas flows, are suitable. Due to the feed of breathing gas enriched with anesthetic and the drawing off of a corresponding compensation volume, the volume of the anesthetic being fed can be better adapted to the patient&#39;s needs. 
         [0012]    It is especially advantageous to combine the sampling device with an anesthetic measuring device, which is needed anyway, and to feed the breathing gas drawn off directly into the anesthetic dispenser. 
         [0013]    The gas analysis port for the sampling device is advantageously arranged between the connecting branch for the anesthetic feed and the patient. However, it is also possible, as an alternative, to provide the gas analysis port for the sampling pump directly at the filter device. 
         [0014]    Separate line sections for the breathing gas and the expired gas are advantageously provided in the area of the breathing gas line. The gas flow is controlled by means of switchover valves such that the overwhelming majority of the gas to be breathed in flows through an inspiration channel section and the expired gas enters an expiration channel section. The anesthetic dispensing is advantageously carried out in the expiration channel section. Both the anesthetic expired by the patient and the anesthetic newly fed in are stored in this manner in the adsorber bed of the filter device during the expiration phase. The anesthetic is again released into the gas to be inspired during the next inspiration stroke. A uniform supply of anesthetic into the breathing gas is thus achieved. 
         [0015]    An exemplary embodiment of the present invention is shown in the figures and will be explained in more detail below. 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 drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    In the drawings: 
           [0017]      FIG. 1  is a schematic view showing a first device according to the present invention with an anesthetic dispenser; 
           [0018]      FIG. 2  is a schematic view showing an alternative device to  FIG. 1 , in which separate gas channels are provided for gas to be inspired and expired gas; 
           [0019]      FIG. 3  is a schematic view showing a device with regulation of the anesthetic dispensing; and 
           [0020]      FIG. 4  is a schematic view showing a device with an anesthetic dispenser, which is supplied from an external gas source. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Referring to the drawings in particular,  FIG. 1  schematically illustrates the design of a first device  1  according to the present invention with a respirator (also known as a ventilator)  2 . The respirator  2  is connected to a breathing gas source  3  and dispenses breathing gas in an inspiration line. Expired breathing gas enters via an expiration line  5  a gas outlet  6  with a waste gas disposal, not shown more specifically. 
         [0022]    The inspiration line  4  and the expiration line  5  are connected to one another via a Y-piece  7 , and a breathing gas line  8  between a filter device  9 , arranged downstream of the Y-piece  7  and a patient  10 , supplies the patient  10  with breathing gas. The filter device  9  contains an adsorber bed  11  for adsorption and desorption of anesthetic and a heat and moisture exchanger  12 , which adsorbs moisture present in the breathing gas during the expiration phase and releases same into the breathing gas again during the next inspiration stroke. Expired anesthetic is retained in the adsorber bed  11 , which consists of activated carbon fibers, and is again fed into the gas to be inspired during a desorption phase at the time of the next inspiration stroke. 
         [0023]    A connecting branch  13  for feeding the anesthetic and a gas analysis port  14  are arranged in the breathing gas line  8 . The gas analysis port  14  is located in the vicinity of the patient between the patient  10  and the connecting branch  13 . An anesthetic measuring device  15 , connected to the gas analysis port  14  contains a sampling pump  16 , which draws in breathing gas continuously from the breathing gas line  8  and passes same on to the gas inlet  17  of an anesthetic evaporator  18 . The anesthetic evaporator  18 , which operates according to the bypass principle, adds anesthetic vapor to the breathing gas drawn off and is connected by its gas outlet  19  to the connecting branch  13  of the breathing gas line  8 . A volume flow detector  201  monitors the gas volume drawn off by the sampling pump  16 . The anesthetic measuring device  15  contains a gas analyzer, with which the constituents of the breathing gas, such as the oxygen concentration, the carbon dioxide concentration and the anesthetic concentration, are determined. 
         [0024]    An anesthetic evaporator operated according to the bypass principle is shown as an example in DE 196 13 754 C1 (corresponding to U.S. Pat. No. 5,671,729). As an alternative to an anesthetic evaporator, it is also possible to use an anesthetic dispenser for anesthetics with a low boiling point, such as desflurane, as it is described as an example in DE 10 2004 054 416 B3 (U.S. 2006065269). Reference is expressly made to the entire disclosure contents of DE 196 13 754 C1 and DE 10 2004 054 416 B3. U.S. Pat. No. 5,671,729 and U.S. 2006065269 are hereby incorporated by reference in their entirety. 
         [0025]      FIG. 2  illustrates a second device  20 , which is provided with an alternative connecting branch  131  for anesthetic compared to the first device. Identical components are designated by the same reference numbers as in  FIG. 1 . The alternative connecting branch  131  has an inspiration channel section  132 , through which predominantly gas to be inspired flows, and an expiration channel section  133  for the expired gas. The connecting branch  131  contains switchover valves, not shown more specifically, which send the gas to be inspired and the expired gas through the corresponding channel sections  132 ,  133 . The anesthetic is dispensed directly into the expiration channel section  133 , so that it is stored at first in the adsorber bed  11  at the end of the expiration stroke. The anesthetic is again released into the gas to be inspired during the desorption phase during the next inspiration stroke. Concentration peaks in the gas to be inspired are avoided due to the intermediate storage of the anesthetic dispensed in the adsorber bed  11 . 
         [0026]      FIG. 3  shows a third device  30 , in which a gas analysis port  141  is arranged, compared to the first device  1  according to  FIG. 1 , directly behind the filter device  9 . The gas sampling, gas analysis and anesthetic supply take place via a combination device  31 , which contains, in a modular design, a sampling pump  35 , an anesthetic dispenser  36  and an anesthetic measuring device  37 . The combination device  31  is connected to the respirator  2  via a signal line  32 . Data of the respirator  2  are transmitted via this signal line  32  to the combination device  31 , which is suitable for making it easier for the user to set the anesthetic concentration. These data are, for example, the respiratory minute volume, the peak flow, the patient&#39;s body weight and the patient&#39;s age. The combination device  31  contains a regulator  33 , which is designed, in conjunction with a set point adjuster  34  for the anesthetic concentration, to set a predetermined anesthetic concentration in the breathing gas. 
         [0027]    In a fourth device  40  corresponding to  FIG. 4 , the gas to be inspired is sent by means of switchover valves  41 ,  42  via a first gas path  45 , and the expired gas is sent back to the filter device  9  via a second gas path  46 . The connecting branch  9  for the anesthetic supply is arranged in the second gas path  46 , so that the anesthetic enters the expired gas only. The gas for the anesthetic evaporator  18  is removed from the breathing gas source  3  via a volume flow regulator  43 . Compensation between the gas volume drawn off and the gas volume fed in is carried out via a data line  44  between the volume flow regulator  43  and the sampling pump  16 , so that the volume balance is compensated. 
         [0028]    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. 
       APPENDIX 
     LIST OF REFERENCE NUMBERS  
       [0000]    
       
           1  First device 
           2  Respirator 
           3  Breathing gas source 
           4  Inspiration line 
           5  Expiration line 
           6  Gas outlet 
           7  Y-piece 
           8  Breathing gas line 
           9  Filter device 
           10  Patient 
           11  Adsorber bed 
           12  Heat and moisture exchanger 
           13 ,  131  Connecting branch 
           132  Inspiration channel section 
           133  Expiration channel section 
           14 ,  141  Gas analysis port 
           15 ,  37  Anesthetic measuring device 
           16 ,  35  Sampling pump 
           17  Gas inlet 
           18  Anesthetic evaporator 
           19  Gas outlet 
           201  Volume flow detector 
           20  Second device 
           30  Third device 
           31  Combination device 
           32  Signal line 
           33  Regulator 
           34  Set point adjuster 
           36  Anesthetic dispenser 
           40  Fourth device 
           41 ,  42  Switchover valve 
           43  Volume flow regulator 
           44  Data line