a first embodiment of a tube 2 according to the invention is shown in fig1 . the tube 2 has a housing 4 that , as in normal tubes , is cylindrical . an absorbent 6 for carbon dioxide is arranged internal the housing 4 , against its inner wall . a membrane 8 is arranged inside of the absorbent 6 . the membrane 8 is permeable to carbon dioxide . it should be noted that the relative thicknesses of the housing 4 , the absorbent 6 and the membrane 8 are not shown in their correct proportions in the fig1 . since the absorbent 6 occupies only a portion of the cross - sectional area of the tube 2 , the 2 interior of the tube 2 may easily be made so that the absorbent 6 provides no or only a small resistance to flow without impeding its efficiency in absorbing carbon dioxide . carbon dioxide in a breathing gas passing through the pipe will diffuse through the membrane 8 and be absorbed in the absorbent 6 . by the tube 2 being stretched the adsorption of carbon dioxide can occur over a longer time interval than would be possible with the same volume of absorbent collected in a container . the tube 2 may in principle be so long as to form the entire inspiration branch of a tubing system of an anesthetic system ( described in more detail in connection with fig3 ). the absorbent 6 and the membrane 8 are , in the first embodiment , also cylindrical . this is , however , not essential . the absorbent 6 alternatively may be placed over only a portion of the inner surface of the housing 4 . there could even be a number of absorbents along the inner surface . a second embodiment of the invention is shown in fig2 in the form of a tube 10 . the tube 10 , in common with the foregoing embodiment , is provided with a housing 4 that can be identical to the foregoing and is therefore given the same reference numeral . a cylindrical absorbent 12 is , in this case , suspended in the middle of the tube &# 39 ; s 10 flow path in a suitable manner using stays , a mesh or other means . a flowing gas usually has a velocity profile that is fastest in the middle of a pipe and is slowest at its walls . this placement therefore results in the absorbent 12 coming into faster and more direct contact with the carbon dioxide in the gas . moreover , the absorbent 12 creates turbulence that in turn increases the contact between the carbon dioxide in the gas and the absorbent 12 . again , the absorbent 12 occupies only a portion of the cross - sectional area of the tube 10 . the flow - through area around the absorbent 12 can readily be as large as in other sections of the flow pathways of a tubing system ( as discussed in connection with fig3 ). also in this case there may be a number of absorbents 12 positioned after each other in the middle of the flow path of the tube 10 . it should be noted that the absorbent 12 ( likewise the absorbent 6 ) may be formed of any carbon dioxide absorbing material . it is , however , advantageous to select a material having as high an absorbtion capacity per unit volume as possible . a combination of the two embodiments is also possible , with the absorbent being placed both in the middle of the housing and along the inner walls . an anesthetic system 14 according to the invention is shown schematically in fig3 . the anesthetic system 14 has an anesthetic apparatus 16 and a tubing system 18 according to the invention . the tubing system 18 has , inter alia , a unit 20 for the adsorption and desorption of gaseous anesthetic ; an inspiration branch 22 ; a patient connection 24 ; and an expiration branch 26 . a tube 2 , 10 according to a one of fig1 and 2 is arranged in the inspiration branch 22 in order to absorb carbon dioxide . notably , the open flow through area in the tube 2 , 10 can readily be made coherent with the rest of the tubing system 18 , especially the rest of the inspiration branch 22 . this means that the absorbent 6 , 12 will essentially provide no or only a small addition to the overall flow resistance of the tubing system 18 . it is also feasible to shape the tube 2 , 10 so it forms the entire inspiration branch 22 . the absorbent 6 , 12 ( or a number of absorbents ) then could be evenly distributed throughout the entire length of the tube 2 , 10 . for further details concerning the anesthetic apparatus 14 or the tubing system 18 reference is made to the earlier mentioned u . s . pat . nos . 5 , 471 , 979 and 6 , 152 , 133 . although modifications and changes may be suggested by those skilled in the art , it is the intention of the inventor to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art .
a tube for use in an anesthetic system has an essentially cylindrical housing . more effective take - up of carbon dioxide is achieved by an absorbent for carbon dioxide that is arranged within the tube .