Abstract:
A CO 2  absorber bypass for an anesthesia machine includes a diverter for diverting exhaled gas to bypass the CO 2  absorber of the anesthesia machine when the diverter is activated. The CO 2  absorber bypass further includes a shunt for conveying the diverted exhaled gas, a coupler for connecting the shunt to the inhalation limb of the anesthesia machine, a shunt one way valve, a shunt adjustable pressure limiting valve, and a shunt reservoir. The CO 2  absorber bypass allows the CO 2  absorber to be changed while the exhalation limb conveys exhaled gas from a patient and the inhalation limb conveys gas to the patient.

Description:
FIELD OF THE INVENTION 
     The invention related to a CO 2  absorber bypass for an anesthesia machine and to an anesthesia machine having such a CO 2  absorber bypass. 
     BACKGROUND OF THE INVENTION 
     Events occurring during general anesthesia may require CO 2  absorber bypass. Included in these events would be situations in which the absorber granule indicator change has alerted the anesthesiologist to the need for canister replacement. In an extremely urgent situation such as malignant hyperthermia (MH) it is imperative to bypass the absorber canisters in the shortest time possible. The device according to an aspect of the present invention can be utilized whenever CO 2  absorber bypass is indicated and desirable. 
     Normally during anesthesia exhaled gases are conducted to the CO 2  absorber while fresh gases are conducted to the patient during inhalation. Exhaled gases having been absorbed by the canisters exit the absorber and are joined with incoming fresh gases and return to the patient thereby starting a new cycle. 
     In present day anesthesia machines, the patient circuit prevails and exists commercially in several versions. Generally, the two limb circuit version comprises separate inhalation and exhalation limbs. A second version conducts the inhaled gases toward the patient via a manifold tube and enters a coaxial circuit in which fresh gases are conducted through an inner concentric tube while the exhaled gases are conducted through an outer concentric tube. There are other versions of anesthesia delivery utilizing absorbers and wherever bypassing the absorber is indicated the invention will suffice. 
     Perusal of the internet for patents in the same field of endeavor reveals the following: 
     A) W. C. Hamilton Mar. 2, 1954 Filed, Jun. 7, 1952 U.S. Pat. No. 2,693,181. This intra-canister container bypass requires complete overhaul or substitution of an apparently intricate, costly device, which has not been exhibited at anesthesia national conferences.
 
B) Chen et al United States Patent Application Publication Pub. No.: US 2009/0056720 A1 Pub. Date: Mar. 5, 2009. “Apparatus for Installing or Uninstalling Carbon Dioxide Absorbent Canister . . . comprises a body, a lifting member, and a lifting mechanism”. This intra-canister container mechanism reveals an obviously radical, costly departure from standard commercially available devices, wherein currently the CO 2  absorbent canisters are disposables, this device requires a complete overhaul of prevailing practice. Like “A”, this patent has not been marketed to practitioners of anesthesia.
 
     Neither of these patents have claims for pre- or post-canister container sites. Both prior art bypass attempts require both hands to be utilized during the maneuvers. The bypass according to an embodiment of the present invention can be accomplished using one hand or, when utilized automatically, neither hand. 
     SUMMARY OF THE INVENTION 
     It is an aspect of the invention to bypass the CO 2  absorber. In the double limb version, a diverter means will shunt a breath across the patient circuit containing a unidirectional valve, APL (pop-off valve), and “T” connector. The coaxial version will have a directional valve, APL valve, diverter with shunt and “T” connector. Whenever parts of the original patient circuit are bypassed they will be replaced in the bypass circle. While it appears redundant, they are inserted into the circuit in order to maintain functionality. The parts can be inserted into the circuit as separate attachments, in fixed or disposable options 
     The bypass can be situated distal to the exhalation/unidirectional and inhalation/unidirectional valve. Various locations for its components can be selected along the circuit path. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram of a typical double limbed patient circuit. 
         FIG. 2  is a diagram of a double limbed patient circuit having a CO 2  absorber bypass according to the present invention. 
         FIG. 2A  is an enlarged diagram showing the bypass path of  FIG. 2 . 
         FIG. 3  is a diagram of a single limbed patient circuit having a CO 2  absorber bypass according to the present invention. 
         FIG. 3A  is an enlarged diagram showing the bypass path of  FIG. 3 . 
         FIG. 4  is another diagram of a typical double limbed patient circuit. 
         FIG. 5  is another diagram of a double limbed patient circuit having a CO 2  absorber bypass according to the present invention. 
         FIG. 6  is another diagram of a double limbed patient circuit having a CO 2  absorber bypass according to the present invention. 
         FIG. 7  is another diagram of a double limbed patient circuit having a CO 2  absorber bypass according to the present invention. 
         FIG. 8  is another diagram of a double limbed patient circuit having a CO 2  absorber bypass according to the present invention. 
         FIG. 8A  is an enlarged diagram showing the bypass path of  FIG. 8 . 
         FIG. 9  is another diagram of a patient circuit having a CO 2  absorber bypass according to the present invention, with different possible locations for the bypass shown. 
         FIG. 10  is a diagram of a portion of a patient circuit having a CO 2  absorber bypass according to the present invention, with another location for the bypass shown. 
         FIG. 10A  is an enlarged diagram showing the bypass path of  FIG. 10 . 
         FIG. 11  is a schematic diagram of a patient circuit having a CO 2  absorber bypass according to the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The device bypasses the CO 2  absorber of the patient circuit. It utilizes the original directional valve and APL valve when situated distal to the patient. It utilizes a diverter means, a shunt means and a connector means conducting a breath to the inhalation limb of the patient circuit. In the proximal situation, the embodiments consist of a diverter means, a shunt means, a directional valve, and a connector means. Components which become excluded by the bypass can be included in the device bypass according to the invention in order to reestablish function of the bypassed components. The embodiments of proximal sites can be disposable aiming to minimize cross-contamination and to maximize good hygienic outcomes. Cooling means and automatic actuation can be included. 
     In distal embodiments there are: 
     1) Post-canister container sites, in which an embodiment of the invention begins and begins or ends after the unidirectional valve and APL valve and begins or ends after the canister and before the fresh gas inlet. 
     2) Pre-canister container sites, in which an embodiment of the invention begins or ends after the unidirectional valve and APL valve and begins or ends after the fresh gas inlet. 
     3) At the fresh gas inlet, in which an embodiment of the invention begins or ends at the fresh gas inlet and begins or ends at the inhalation route. 
     In current common usage as shown in  FIG. 1 , an exhaled breath from the patient travels from the patient (mask tracheal tube, LMA, etc.)  1 , through the exhalation limb  2 , through the reservoir (bag or ventilator connector)  3 , through the exhalation/unidirectional valve  4 , where it progresses onward through the APL valve  5 , CO 2  canister  8 , joins the incoming gases at connection  9 , passes through inhalation/unidirectional valve  14 , through the patient inhalation limb  15 , and return to the patient via “Y” piece  16 , and the cycle is repeated. 
       FIG. 2 , a double limbed circuit, shows an exhaled breath from a patient  1 , flows through the exhalation tube  2 , through the embodiment of diverter means  17 , through the unidirectional valve  4 , reservoir bag  3 , APL valve  5 , onward through the CO 2  absorber  8 , continues past and joining with the incoming fresh gases from inlet  9 , through the anesthesia machine inhalation limb  10 , through the inhalation/unidirectional valve  14 , through the bypass “T” connector  21 , through the inhalation tube  15 , onward to the patient and thus repeating the cycle. 
     In bypass mode, the path is directed by the diverter means  17  through alternate direction mode inset  17   a  (see  FIG. 2A ), through the bypass shunt  18 , shunt unidirectional valve  19 , and shunt APL valve  20 , and admixes at connector  21  with confluent gases coming from fresh gas inlet  9 , and onward through inhalation tube  15 , back to the patient&#39;s mask via “Y” tube  16 , thus repeating the cycle. A reservoir bag can be placed at any site selected as shown in  FIG. 2 . 
     The redundancy of illustrated embodiments of the unidirectional valve and APL valve and some stopped and unstopped versions of the reservoir bag in the bypass and other sites is necessary whenever restoration of lost function is indicated, considering that some components can be bypassed in alternate direction mode  17   a  when the bypass is actuated. 
     The invention is intended for any and all circumstances in which CO 2  canister bypass is indicated and/or desirable. 
     Noteworthy are some optional sites for the shunt reservoir bag  3   a ,  3   b ,  3   c , and  3   d  and  3   e . At positions  3   a  and  3   d  for example the reservoir bag is stopped  27 , during normal use. 
     Cooling means  26 , automatic operation of the diverting means, and disposable parts and combinations of the invention are optional. 
     Prevailing anesthesia equipment utilizes corrugated flexible disposable tubing. While this is adequate for the invention, the parts thereof may consist of any materials that serve the purpose of the invention. 
     In,  FIG. 3 , a coaxial breathing circuit is shown. The original (un-bypassed) pathway for the exhaled breath leads past the reservoir bag  3 , exhalation/unidirectional valve  4 , APL valve  5 , and the diverting means  17  in the usual position passing through absorber  8 , adding fresh gas at  9 , and returning to patient  1 . 
     In bypass mode, an exhaled breath travels through the outer concentric tube  25 , progresses past chamber  23 , leads the exhaled gas through the diverter means  17   a  through the bypass shunt  18 , past the bypass unidirectional means  19 , and past the bypass APL valve  20 , through the “T” connector  21 , which lies downstream from the inflowing fresh gases  10  and an inhalation/unidirectional valve  14 . The gas flow returns to the inhalation limb of the patient circuit via the manifold tube  22 , enters the coaxial chamber  23 , and continues on through the inner concentric tube  24 , and project onward to the patient  1 . 
     Noteworthy are optional positioning sites for the bypass reservoir bag at  3   a - d  and at any position necessary to achieve proper function. For example, at positions  3   a  and  3   d  the bag stem is stopped  27 . Optional cooling fins  26  can be applied to lengths of the conductor means  18 . 
     The bypass can be actuated automatically or manually. 
     In  FIG. 4 , the embodiment of an anesthetic patient circuit is shown in two-dimensional view. This form is utilized in subsequent illustrations. 
     In  FIG. 5 , diverting means  17  is situated along the patient circuit pathway between the APL valve  5  of the exhalation arm of the patient circle and the CO 2  absorber container  8 . It illustrates the usual route of gases through the diverting means  17 , past the canister container through the connector means  13 , and returns to the patient circle inspiration arm  15  to renew the cycle. 
     In  FIG. 5A , diverting means  17   a  connects from tube  6  in bypass mode to the connector means  13 , thus bypassing the canister  8 . 
     The usual flow path through the connector means  6 , in  FIG. 6  runs through canister container  8  and flows past the diverter valve means  17  through the tube  10  and on to the patient inspiration circle at connector means  21  and continues on to inhalation limb  15 , and onward to the patient  1  where the circuit is completed and restarted. 
     The flow of gases by means of connector  6  in  FIG. 7  diverts the flow of gases through bypass tube  18  past the canister container  8  to the diverting means  17  which is situated at or near the fresh gas inlet port  9 . Diverting means  17  is placed anywhere along the tube  10  which leads the gases exiting the absorber canister upward to join the fresh gas inlet  9  and the limb  18  which leads into the patient inhalation circle  15 . 
     In  FIG. 8 , the usual direction of an exhaled breath is depicted showing diverter means  17  placed between the exhalation unidirectional valve and absorber  8 . Bypass tube means  18  intersects with inspiration tube of the patient circle at connector means  21 , and diffuses with fresh gases and is conducted through directional valve  14  and on to patient  1  reentering the patient circle. 
     In  FIG. 8A , bypass mode is illustrated. Diverting means  17 , rotated clockwise toward shunt means  18 , directs a breath path at alternate route to connector “T”  21 . Gases are conducted through inhalation/directional valve  14  to return to patient  1 . In selected instances whenever a diverting means is utilized, automatic as well as manual controls can be opted. Symbols “T” and “Y” are interchangeable, and entail embodiments of varying angularities, flexibilities, and consistencies. They include all related connector situations. 
     In  FIG. 9 , illustrated examples show infinite optional sites of diverter means  17 , pre, intermediate and at canister or other nearby placements between anesthesia machine  50  and fresh gas inlet a, b, and c. Options are illustrated in un-bypassed and bypassed mode. 
     In un-bypassed mode gases leaving anesthesia machine  50  route through diverter means  17  pass through shunt tube  18  to intersect with “Y” connector  21 , and allows flow through connector  21 , travel through inhalation-unidirectional valve  14 , and continue onward to patient  1  via tube  15  and the breathing cycle is repeated. 
     In bypassed mode gases leaving anesthesia machine  50  are directed from their original route through the fresh gas inlet to shunt tube  10  and reenter the patient inhalation limb through connector  21  and continue through directional valve  14  and continue as in the un-bypassed circuit. 
     In  FIG. 10 , illustrated is another option of diverter means placements between fresh gas port  9  and exhalation tube  6 . The usual route of the exhaled breath passes through the absorber canister  8 . It flows through the diverter means  17 , diffuses with fresh gas at connector port  9 , and continues its journey patient-ward through tube  10  to complete the circuit. 
     In  FIG. 10A , an exhaled breath bypasses the absorber  8  at connector  6  through tube  18 , changes direction when the diverter means  17  is rotated thus detouring past the fresh gas port  9 , enters tube  10  and continues its journey patient-ward through tube  10  to complete the circuit. 
     In summary, the device according to the present invention can be located in several locations: 
     1) Post-canister container site. 
     2) Pre-canister container site. 
     3) Intra-canister container site. 
     4) At the fresh gas inlet. 
     5) Proximal to the exhalation unidirectional valve and APL valve, there are varying locations of breathing reservoir. Present day usage consists of flexible disposable tubing found in either: 
     a) Two limb circuit. 
     b) Coaxial circuit. 
     Rapid removal of the CO 2  absorber from the patient circuit during general anesthesia is sometimes necessary. In order to maintain uninterrupted breathing, bypass of the patient circuit is required. This is accomplished by positioning a diverter means, shunt means, and “T” connector means. In circumstances in which the unidirectional valve, APL valve and connector and reservoir bag are omitted from the circuit, they can be restored as parts of the bypass, thus retrieving function which would have been lost had they not been included. 
     Various sites for the reservoir bag can be chosen. The device can be disposable to prevent cross contamination. The scope of this invention covers bypass of the CO 2  absorber in times of acute emergency, and on all occasions when CO 2  canister bypass is indicated. 
     Cooling fins and automatic actuation are optional embodiments.