referring to fig2 , 2 a and 3 - 6 , an hme / bypass device 20 includes a ventilator - side section 22 having a ventilator - side port 21 , and a patient - side section 35 having a patient - side port 25 . a knurled , rotatable collar 23 a of a valve plate 23 is used to control a 2 - way valve located inside of a complete housing including both ventilator - side section 22 and patient - side section 35 . the outer surface of ventilator - side port 21 is partially knurled , as shown . a co2 monitoring port 42 is provided as an integral part of a ventilator - side section 22 , and a drainage port 43 is provided as an integral part of patient - side section 35 . fig2 a shows a ventilating system 100 in which hme / bypass device 20 can be connected , wherein a ventilator 101 is coupled by suitable respiratory tubing to one port of an mdi ( metered dose inhaler ) injection device 103 having an opposite port connected by suitable respiratory tubing to ventilator - side port 21 of hme / bypass device 20 . hme / bypass device 20 includes a patient - side port 25 which is connected to an endotracheal tube 107 that has been intubated into the trachea of a patient . the air pumped by ventilator 101 into ventilator - side port 21 does not carry any aerosolized medication unless an mdi canister 105 is inserted into mdi injection device 103 and depressed so as to open the valve of mdi canister 105 . knurled collar 23 a is initially set to a position that causes air from ventilator 101 to pass through an optional annular bacterial and viral filter 48 disposed in ventilator side chamber 40 a and through an annular hme element 15 in the patient side chamber 50 a ( as shown in fig3 ) and then through patient - side port 25 and endotracheal tube 107 into the lungs of the patient . if it is desirable to administer aerosolized medication to the patient , then knurled collar 23 a is rotated 90 degrees to a second position which causes air pumped by ventilator 101 to pass directly from ventilator - side port 21 through patient - side port 25 without passing through hme element 15 or the optional bacterial and viral filter element 48 . then , an mdi canister 105 containing the desired medication is inserted into an injection port of mdi injection device 103 and depressed so as to open a valve of mdi canister 105 and thereby cause a plume of medication droplets / particles to be sprayed into the air stream produced by ventilator 101 . the plume of medication droplets / particles is carried directly through an un - obstructed path through hme / bypass device 20 and endotracheal tube 107 into the lungs of the patient . this prevents medication droplets / particles from being deposited on hme element 15 or the optional bacterial and viral filter element 48 . alternatively , a device other than an mdi injection device 103 , such as a liquid nebulizer , might be used to introduce aerosolized medication into the stream of air produced by ventilator 101 . referring to fig3 - 6 , ventilator - side port 21 of hme / bypass device 20 includes a cylindrical passage 21 a that extends into an interior first chamber 40 a bounded by a first chamber wall 40 that is integral with the cylindrical tube that forms / bounds passage 21 a . a portion of passage 21 a extends into first chamber 40 a and forms a cylindrical left cage 30 , the right end of which includes a narrow cylindrical section 31 . half of the right end of passage 21 a is blocked by two sections of a circular disk 32 , as shown in fig4 . as shown in both fig3 and 4 , the main cylindrical wall of cage 30 has a number of elongated , rectangular , uniformly spaced openings 30 a . the right peripheral edge of ventilator - side section 22 is bounded by a planar , annular surface 34 ( fig4 ) which abuts and slides against a corresponding annular planar surface of annular ring 23 b of valve plate 23 , as shown in fig6 . an o ring 45 a is disposed in a circumferential o ring grove 45 around the outside surface of chamber wall 40 and performs a seal with the inside surface diameter of knurled collar 23 a . a receiving boss 81 is positioned on the inside diameter of chamber wall 40 to receive a keying post 52 ( fig5 ) to ensure proper alignment of patient - side section 35 with ventilator - side section 22 , annular ring 23 b of valve plate 23 being “ sandwiched ” between annular planar face 34 of ventilator - side section 22 and annular planar surface 50 b of patient - side section 35 . keying post 52 also acts as a stop to limit the 90 degree rotation of valve plate 23 in either direction by engaging the portions of spokes 23 c and 23 g between outer ring 23 b ( fig6 ) and middle ring 23 d . the details of valve plate 23 are shown in fig6 . knurled collar 23 a surrounds and is rigidly attached to a planar structure including two flat , co - planar , diametrically aligned spokes 23 c and two flat , co - planar , diametrically aligned spokes 23 f which are perpendicular to spokes 23 c . the planar structure also includes three flat , co - planar , concentric , annular rings , including above mentioned outer annular ring 23 b , and also includes middle ring 23 d and inner ring 23 e . outer ring 23 b is rigidly attached to the inner diameter surface of knurled collar 23 a , and is connected to the outer end of each of spokes 23 c . middle ring 23 d is attached to a mid portion of each of spokes 23 c . the inner end of each of spokes 23 c is rigidly attached to opposed portions of the outer cylindrical surface of an outer cage 70 . an outer end of each of spokes 23 f is attached to and integral with middle ring 23 d . the inner end of each of spokes 23 f is rigidly attached to opposed portions of the outer cylindrical surface of outer cage 70 . a main cylindrical surface of outer cage 70 ( fig6 ) has therein a plurality of uniformly spaced , elongated openings 70 a that can be selectively aligned with or misaligned with openings 60 a in inner cage 60 ( fig5 ) in order to either ( 1 ) allow air from ventilator 101 ( fig2 a ) to flow through hme element 15 and openings 60 a or ( 2 ) block openings 60 a . the selective alignment or misalignment is achieved by rotating knurled collar 23 a through 90 degrees ( relative to the complete chamber wall 40 , 50 with valve plate 23 “ sandwiched ” between left annular surface 34 and right annular surface 50 b ). a semi - circular disk 24 covers half of the inner end of outer cage 70 . two sectors of circular disk 24 cover part of the inner end of outer cage 70 . referring to fig5 and 6 , the inner surface of outer cage 70 of valve plate 23 can slide over the outer surface of inner cage 60 of a ventilator - side section 22 when it , valve plate 23 , and patient - side section 35 are assembled into the unitary structure shown in fig2 and 3 . the annular , planar face 50 b of patient - side section 35 abuts and slides against the front face of outer ring 23 b ( fig4 ), and the keying post 52 attached to the inner surface of right chamber wall 50 of patient - side section 35 extends into the corresponding receiving boss 81 of left chamber wall 40 . a second o ring groove 46 ( fig3 and 5 ) is circumferentially formed in the outer surface of chamber wall 50 , and a second o ring 46 a is supported in second o ring groove 46 . the first o ring 45 a forms a seal between valve plate 23 and ventilator - side section 22 , and the second o ring 46 a forms a seal between valve plate 23 and patient - side section 35 . ventilator - side section 22 and patient - side section 35 both will be permanently snapped on to valve plate 23 . preferably , all of the components of hme / bypass device 20 with the exception of the hme element 15 and the optional bacterial and viral filter are composed of suitable plastic , such as clear abs plastic , acrylic , polycarbonate , or polypropylene . when valve plate 23 is rotated to a first position such that its two openings 24 a are precisely aligned with the two openings 60 a of ventilator - side section 22 , then semicircular opening 24 a adjacent to disk sectors 24 are also precisely aligned with the openings 32 a adjacent to disk sectors 32 , thereby providing a clear passage from ventilator - side port 21 to patient - side port 25 . at the same time , the solid “ vanes ” 70 b of outer cage 70 ( fig6 ) are precisely aligned with openings 60 a of inner cage 60 , and thereby prevent air carrying aerosolized medication from passing through hme element 15 , optional bacterial and viral filter 48 , and openings 60 a , so essentially all of the aerosolized medication flows unobstructed through the endotracheal tube 107 into the patient &# 39 ; s bronchial passages and lungs . when valve plate 23 is rotated 90 degrees from the first position to a second position such that its disk sectors 24 are precisely aligned with the openings 32 a of ventilator - side section 22 , then disk sectors 32 adjacent to openings 32 a are also precisely aligned with openings 24 a adjacent to disk sectors 24 , thereby completely blocking passage of the air from ventilator - side port 21 directly to patient - side port 25 and diverting all of such air from passage 21 a through openings 30 a of left cage 30 into the first chamber 40 a through optional bacterial and viral filter 48 , and through the various gaps between rings 23 b , 23 d and 23 e so the air flows into second chamber 50 a , through hme element 15 in second chamber 50 a , and then through the openings 70 a of outer cage 70 and the aligned openings 60 a of inner cage 60 and into passage 25 a . another embodiment of the hme / bypass device of the present invention is shown in fig7 - 10 . this embodiment has a substantially simpler internal valve structure and an easier - to - use external control for switching between hme operation and bypass operation in which aerosol medication is introduced into the air stream generated by ventilator 101 . where appropriate , the same or similar reference numerals used in fig2 - 6 are also used in fig7 - 10 , sometimes with an added “ 0 ”. referring to fig7 - 10 , hme / bypass device 200 includes a ventilator - side section 220 and a patient - side section 350 that can be press - fit or snap - fit onto ventilator - side section 220 . ventilator - side section 220 has a ventilator - side port 21 having an inlet passage 21 a , gas sampling port ( not shown , but similar to port 42 of fig2 ), and two generally cylindrical ventilator hose connecting surfaces , one being the inner surface of ventilator - side port 21 and the other being the outer surface of a smaller - diameter concentric cylindrical tube 21 b . a standard ventilator hose for coupling to intubated adults can be connected to the inner surface of port 21 , and a smaller ventilator hose for coupling to intubated children can be connected to the outer surface of concentric cylindrical tube 21 b . similarly , a smaller ventilator hose can be coupled to the inner concentric cylindrical tube 25 b on patient - side port 25 for coupling to a ventilator circuit adapted for children . a butterfly valve assembly is mounted axially within the housing formed by ventilator - side housing 400 and patient - side housing 500 . the valve assembly , shown in fig8 - 10 , is supported by six vanes 54 which are integral to the ventilator - side housing 220 and are symmetrically positioned around a gas flow path that is concentric with ventilator - side housing 220 . a cylindrical valve housing 37 is axially supported by the inner edges of the six vanes 54 . one or more of the opposed vanes 54 extends between a pair of axial ribs 58 , which are integral with the valve housing 37 and which are spaced far enough apart to accommodate the vanes 54 . the vanes 54 support valve housing 37 so that the end thereof closest to the wall of ventilator - side housing 220 is spaced from it by a gap 55 through which air from ventilator 101 can flow when the valve is closed , thereby causing the air from ventilator 101 to be diverted around , rather than through the valve housing 37 . a semicircular slot 38 in the upper surface of valve housing 37 is wide enough to allow the planar , semicircular vanes 74 of the butterfly valve and a valve post 78 to which vanes 74 are attached to pass through during assembly . the diameter of the circle formed by the outer edges of the two vanes 74 is slightly less than inside diameter of cylindrical valve housing 37 , in order to allow the butterfly valve to be smoothly opened and closed by rotating an actuation knob 230 attached to the upper end of a valve actuation stem 73 having a lower male coupling element 73 a which engages a female coupling element 77 attached to the top of valve post 78 . as shown in fig8 , hme filter 15 has an annular shape and fits snugly over the outer surface of valve cylinder 37 . the outer radial surface of hme filter 15 fits snugly against the inner cylindrical surface of patient - side housing 500 . therefore , when the butterfly valve is closed so that vanes 74 block the inner cylindrical passage through valve cylinder 37 , air from ventilator 101 passes through an annular gap 55 and through hme filter 15 before then passing through patient - side port passage 25 a and through a suitable ventilator hose to endotracheal tube 107 ( fig2 ). however , if actuation knob 230 is rotated 90 degrees from its closed position so that vanes 74 are parallel to the longitudinal axis of valve cylinder 37 , then air from ventilator 101 containing aerosol medication injected from mdi canister 105 into the airstream by means of mdi injection port 103 , passes freely through the unrestricted valve cylinder 37 and from there into the intubated patient , without loss of any medication particles that would otherwise be removed by hme filter 15 . the structure of the valve assembly including vanes 74 and valve post 78 is shown in fig1 . a flexible snap - on anchor 78 a is provided at the bottom of valve post 78 , and has an associated slot 78 d provided in the lower end of valve post 78 to allow flexing that allows the bottom end of valve post 73 to be snapped into and retained in a hole 41 in the bottom of valve cylinder 37 . the bottom of female coupling element 77 limits the depth to which vanes 74 can be passed through slot 38 and an upper hole 44 in valve housing 37 . a valve actuator stem 73 extends through o - ring 57 ( fig8 ) and ventilator - side housing 400 with the male coupling element 73 a at its base being press fit into an opening 77 a in female coupling element 77 . o - ring 57 is disposed around actuator stem 73 to provide a rotary seal between stem 73 and the ventilator - side housing 400 , and is housed within knob 230 between the inside surface of a boss on the top of ventilator - side housing 400 and actuator stem 73 . ramp style detents ( not shown ) are provided on the outer surface of ventilator - side housing 400 to conveniently index control knob 230 to either its “ valve closed ” or hme position or its “ valve open ” or bypass position . preferably , all of the components of hme / bypass device 200 , with the exception of the hme element 15 and the optional bacterial and viral filter , are composed of suitable plastic , such as clear abs plastic , acrylic , polycarbonate , or polypropylene . hme / bypass device 200 is easily assembled by first inserting the valve mechanism snap fit element 78 a through hole 44 and semicircular slot 38 in valve housing 37 until the bottom of female coupling element 77 comes into contact with the outside diameter of valve housing 37 . valve housing 37 is then inserted between the inside edges of the six radial vanes 54 and pressed into position as shown in fig8 and 9 . actuator stem 73 is subsequently fed through the inside diameter of o - ring 57 and hole 47 in ventilator - side housing 400 with male coupling element 73 a being press fit into female coupling element 77 . hme element 15 is then placed between the outside surface of valve housing 37 and the inside surface of ventilator - side housing 400 , as shown in fig8 . finally , ventilator - side housing 400 is press fit into patient - side housing 500 , completing the assembly . as is the case for the hme / bypass device 20 of fig1 - 6 , an optional bacterial and viral filter 48 can be provided within hme / bypass device 200 , and a gas sampling port 42 and / or a drainage port 43 as shown in fig3 also can be provided for hme / bypass device 200 . the described hme / bypass devices have far smaller “ dead space ” than the bypass tube 8 of the prior art circuvent device 4 shown in fig1 . the described hme / bypass devices , especially hme / bypass device 200 , are much smaller , lighter , less expensive , and easier to use than the combination of the prior art circuvent device with an hme device or hme device connected thereto . the cost of manufacture of hme / bypass device 200 is expected to be only slightly higher than the cost of prior hme devices alone , and much lower than the total cost of the prior art circuvent device in combination with a conventional hme device connected therein as shown in fig1 . while the invention has been described with reference to several particular embodiments thereof , those skilled in the art will be able to make the various modifications to the described embodiments of the invention without departing from the true spirit and scope of the invention . it is intended that all elements or steps which are insubstantially different or perform substantially the same function in substantially the same way to achieve the same result as what is claimed are within the scope of the invention .
a heat and moisture exchanger for both conducting a stream of air produced by a ventilator to a moisturizing medium and internally bypassing the moisturizing medium if aerosolized medication is introduced into the stream includes a housing having a ventilator - side port coupled to an outlet of a ventilator and a source of aerosolized medication . the housing has a patient - side port for coupling to a patient to provide ventilation including either air or air carrying aerosolized medication . a first path conducts air from the ventilator - side port through the moisturizing medium and the patient - side port , and a second path conducts air carrying aerosolized medication from the ventilator - side port directly to the patient - side port . a two - way valve mechanism in the housing selectively couples the ventilator - side port into fluid communication with one or the other of the first and second paths .