the invention will now be described with reference to the drawings . as shown in fig2 the continuous positive airway pressure ( cpap ) device 10 is connected to the proximal end of one lumen 2 of a double - lumen endotracheal tube 1 . normally , there is inserted in the end of the lumen a 15 millimeter connector over which a 22 millimeter connector fits . thus , a 22 millimeter diameter opening in the end of the cpap device to be connected to the single lumen of the double - lumen endotracheal tube would be appropriate . however , it is noted that the cpap device need not fit specifically over the 15 millimeter connector and could fit into a suction port of a double - lumen tube or into the bronchial port of the tube ( neither of which is shown ). a tapered cylindrical fitting 14 extends from the side of the cpap device and is attached to an oxygen tube 21 which , in turn , is connected to a source of oxygen 23 for delivering oxygen under pressure to the cpap device at a constant flow rate . a flow meter 22 for indicating the rate of oxygen flow is included in the oxygen tube 21 . as described with respect to fig1 one leg of the y - connector 6 is clamped by a clamp 7 for disconnecting the anesthesia circuit 4 from the lumen 2 which communicates with the non - ventilated upper lung 9 . the cpap device of my invention also includes a ventilating means v for continuously venting at least a portion of the oxygen supplied by the source 23 to the device 10 . according to the invention , the ventilating means can take different forms , as will be discussed in more detail below . an important feature of all the venting means of my invention is that there always exists an opening through which oxygen can escape , thereby avoiding a dangerous buildup of oxygen to a pressure which could cause overdistention of the non - ventilated lung 9 . in the preferred embodiment of the invention , as shown in fig3 the cpap device includes a long hollow inner cylinder 11 which may be formed of a clear plastic , such as polyvinylchloride . further , a shorter outer cylinder 12 is rotatably disposed snugly over the proximate end 13 of the long inner cylinder 11 . likewise , the shorter outer cylinder 12 may also be formed of a clear plastic . the end 13 of the cpap device 10 is designed to fit onto the proximal end of one lumen of a double - lumen endotracheal tube as discussed above . the distal end of the long inner cylinder 11 is closed by a removable cap 15 . normally , the cap 15 seals the distal end of the cpap device 10 . the cap 15 may be removed in order to slide the end of an anesthesia bag 24 ( fig2 ) over the end of the device . the bag would then fill with oxygen under pressure and , if squeezed , would be used to inflate the lung to which the cpap device is attached . as noted above , the cpap device includes a tapered cylindrical fitting 14 which extends from the side of the long inner cylinder 11 . the oxygen tube 21 is then attached to the fitting 14 to couple the device to the source 23 of oxygen . both the inner and outer cylinders of the cpap device have elongated slots 16 and 17 , respectively , which are aligned longitudinally such that , when the inner and outer cylinders are rotated with respect to one another , the slots line up to allow the venting of varying degrees of oxygen under pressure . hence , by rotating the inner and outer cylinders with respect to each other , the vent opening becomes larger or smaller , depending upon the overlap of the slots 16 and 17 . with the vent opening v maximally closed off , the greatest amount of pressure is generated within the system . on the other hand , with the slots 16 and 17 lined up so as to form the largest opening , the least amount of pressure is generated within the system . as shown in fig4 a , the shorter outer cylinder 12 is rotatably disposed on the long inner cylinder 11 so as to be retained by friction in a position to which it is manually rotated . however , as shown in fig4 b and 4c , the long inner cylinder may be formed with a projection 19 formed on its outer circumference . the projection 19 is engageable with one of a plurality of corresponding notches 20 formed on the inner circumference of the short outer cylinder . in this manner , as the shorter outer cylinder 12 is rotated with respect to the long inner cylinder , and the vent opening becomes larger , one of the notches 20 will catch on the projection 19 at a predetermined cpap level ( e . g ., 5 , 7 . 5 , 10 cm h 2 o cpap ) as denoted by the element numeral 18 . the projection is not required since the short outer cylinder is rotatably disposed in a snug manner on the long inner cylinder . also , an annular rib 25 may be included to engage with a corresponding groove 26 to aid in retaining the short outer cylinder in place . fig5 - 7 illustrate additional embodiments in which alternative forms of the venting means v are employed . in a second embodiment , as shown in fig5 the cpap device 110 comprises a single hollow cylindrical member 111 . again , the cylinder is preferably formed of a plastic , such as polyvinylchloride . as with the previous embodiment , the proximal end 113 of the cylindrical member 111 is connected to a single lumen of a double - lumen endotracheal tube . a tapered cylindrical fitting 114 , for connection with an oxygen tube , and a removable cap 115 are likewise included . in this embodiment , the venting means v takes the form of an elongated slot 116 passing through the wall of the cylindrical member 111 and extending in the longitudinal direction thereof . a slidable plastic tab 112 is disposed in the slot 116 . the tab 112 has a gripping means 117 which may be grasped by the user of the device and pushed or pulled in the longitudinal direction so as to form a smaller or larger vent opening 116 . thus , oxygen under constant , non - varying low levels of positive airway pressure may be transmitted to the non - ventilated lung of a patient during thoracic surgery . predetermined cpap levels are indicated by index marks 118 formed on the outer surface of the cylindrical member 111 adjacent to the slot 116 . fig6 illustrates another embodiment of the cpap device . structural elements similar to those illustrated for the previous embodiments are designated by the same reference numerals but preceded by the numeral 2 . the cpap device 210 is identical to the embodiment shown in fig5 with the exception of the venting means v . in this instance , the venting means takes the form of a plurality of holes 216 of specific calibers ( e . g ., 5 , 7 . 5 , 10 cm h 2 o cpap ) and passing through a hollow cylindrical member 211 . the holes 216 are spaced apart and arranged in a straight line so as to extend longitudinally of the hollow cylindrical member 211 . further , a tab or strip of plastic 212 has a plurality of plastic buttons or pins 217 formed thereon to serve as closure means for the corresponding holes 216 . again , there is always at least one hole open to allow continuous venting of oxygen . in operation , as the tab 212 is pulled and additional holes 216 are opened up , less cpap is produced . in a still further embodiment , as shown in fig7 again the cpap device is identical to the embodiments of fig5 and 6 with the exception of the venting means v . again , identical structural elements as described in previous embodiments are designated with the same reference numerals but preceded by the numeral 3 . in this embodiment , the hollow cylindrical member 311 is again formed with a series of holes 316 of specific calibers . the holes 316 are spaced apart and extend in a straight line longitudinally of the hollow cylindrical member 311 . further , several pins or buttons 312 serve as closure members to individually close the holes 316 . again , there is always at least one hole 316 open to provide venting of oxygen . therefore , with the closing of each additional hole 316 with an individual button 312 , the cpap level in turn increases and vice versa . from the above , it is clear that the embodiments disclosed in fig3 and 5 produce infinitely varying levels of cpap , going from the highest to the lowest level , while the embodiments of fig6 and 7 produce a limited number of discrete levels of cpap . the cpap device according to my invention includes the following advantages : ( 1 ) it is a self - contained device which consists of a single piece of equipment . ( 2 ) it is small , lightweight , and easier to use than alternative , bulky , cumbersome systems . ( 4 ) it eliminates the need for a pressure gauge which is common in the previous &# 34 ; homemade &# 34 ; systems . ( 5 ) it will be easily available to practitioners since it will come packaged with each double - lumen endotracheal tube . ( 7 ) it is safer to use than the &# 34 ; homemade &# 34 ; systems . the alternative prior art systems employ a &# 34 ; pop - off &# 34 ; valve which can be fully closed , allowing a dangerous buildup of pressure within the cpap system and the lung to which it is attached . in my invention , there is always some degree of venting present and thus dangerous pressure levels cannot occur . ( 8 ) it is easier to use than the previously described systems since it has graduated settings to give a precise amount of cpap without the need to precisely adjust a pop - off valve knob while inspecting a pressure gauge . ( 9 ) an attachment for an anesethesia bag allows the option of transiently delivering a higher pressure than the system would ordinarily deliver . this results in opening up previously collapsed alveoli . the cpap then keeps the alveoli from collapsing . ( 11 ) its size and shape make it uniquely compatible for attachment to a single lumen of a double - lumen endotracheal tube . it is contemplated that numerous modifications may be made to the cpap device of my invention without departing from the spirit and scope of the invention as defined in the following claims .
a device for the application of continuous positive airway pressure delivering 100 % oxygen during thoracic surgery utilizing one - lung anesthesia . the device comprises a hollow , cylindrical member serving as a conduit for oxygen . one end of the device is connected to a source of oxygen delivered at a constant flow rate . the opposite end attaches to one lumen of a double - lumen endotracheal tube . a removable cap is attached to the device . if the cap is removed , a breathing bag can be attached for allowing the periodic expansion of the lung connected to the apparatus . a venting device is provided to allow the egress of oxygen under pressure . by changing a venting orifice , varying degrees of pressure of oxygen will be delivered to the one lumen of the double - lumen tube .