embodiments of the present invention will now be described with reference to the above - identified drawings . however , the drawings and the description herein of the invention are not intended to limit the scope of the invention . it will be understood that various modifications of the present description of the invention are possible without departing from the spirit of the invention . also , features described herein may be omitted , additional features may be included , and / or features described herein may be combined in a manner different from the specific combinations recited herein , all without departing from the spirit of the invention . the method of the invention makes use of a tracer which is any non - toxic substance that can be readily detected at low concentrations . suitable materials may be dyes or leuco dyes , isotopic tracers , antigens , or enzymes , for which sensitive methods of detection are well known in the art . the most common , and most preferred tracer is evans blue , or t - 1824 , an azo dye that is readily detected by eye , and can be detected photometrically by absorbance at 626 nm , or by its fluorescence at 680 nm . fig1 is schematic view of a patient intubated with a tracheostomy tube . as shown , the tracheostomy tube has a central lumen 1 , which is a channel allowing for the passage of air , usually provided by an external mechanical ventilator . the device is provided with an inflatable cuff or balloon 11 that , when inflated , separates the trachea into two regions . the first region , between the mouth and the balloon or the “ superior region ” 13 a , also known as the subglottic region . the second region , between the lungs and the cuff , is the “ inferior region ” 13 b . distal to the inferior region 13 b are the lungs 22 . optional elements that are typically present include a bore scope 24 inserted through a port 2 on the endotracheal tube to allow the practitioner to get a direct optical view of region 13 b . guide wires 26 and 28 are attached to the distal tip of the tracheal tube to provide directional guidance . a mechanical aspirator 17 applies suction for aspiration , which is regulated in the embodiment shown by valves 19 and 20 , operated by a controller 16 . the particular tracheal device illustrated for use with the method of the invention has a pair of ports 6 a and 7 a allowing for the aspiration of mucus and other fluids . the invention is not limited to this design , and may be practiced with a wide variety of tracheostomy tubes available to the medical profession . it is only necessary that the device provides at least one suction port above the cuff 11 , which is thereby located in the superior region 13 a when the device is deployed in a patient . manual aspiration ( e . g ., via a syringe ) may be used , but in a preferred embodiment of the invention , an aspirator 17 is used to create negative pressure in order to draw fluids and deliver them to an external canister 15 . the aspirator may be any vacuum suctioning device , such as an impeller pump , a rotary vane pump or similar suctioning devices known in the art . fig2 illustrates the cuff and distal end of an alternative tracheal tube , also useful in the practice of the invention , seen in a side - on view . fused to , or intergral with , the visible side of the airway tube 20 is a lumen 21 connected to an external vaccum source , preferably an aspirator pump . the lumen has a port 23 opening onto a recessed channel 24 on the dorsal side of the tube , and a second port 25 opening onto a seconed recessed channel 26 on the ventral side of the tube . the two channels are not contiguous , being separated on the far side by a similar lumen ( not shown ). the function of the other lumen is not relevant to the present invention ; it may provide air for inflating cuff 22 , vacuum for aspirating the tracheal area distal to the cuff , or fluids for lavage of the trachea . this design is useful in that the channels 24 and 26 each subtend essentially 180 ° of arc around the tube , and together provide essentially 360 ° of coverage . the presence of a second port and channel on the dorsal side , located close to the cuff , enables this design to collect fluids collecting above the cuff on the dorsal side of the tube , as will occur in a patient who is in a reclining or semi - reclining position . in the prior art method of administering the mebdt , a clinician first deflates the cuff and subsequently feeds dye - treated food to a patient . some time thereafter , the inferior region of the trachea ( 13 b in fig1 ) is suctioned , by any of various means known in the art . any food ( and dye ) that may have entered the trachea and traveled past the deflated cuff into the inferior region is collected via such suctioning , and the collected aspirate is examined for the presence of the dye . any such aspiration of food into the inferior region , however , carries with it the risk of infection . in the method of the invention , on the other hand , the cuff is left inflated so that no aspirated material can travel past it into the inferior region . the practitioner deposits several drops of a solution of a tracer on a patient &# 39 ; s tongue , and the patient , if cooperating , swallows . after several minutes to allow any tracer entering the trachea to reach the cuff , the practitioner subsequently suctions the superior region ( 13 a in fig1 ) via the suction ports ( 6 a and 7 a in fig1 ; 23 and 25 in fig2 ). any fluid suctioned from the superior region is collected ( e . g . in external canister 15 ) and evaluated for the presence of the tracer . the presence of tracer in the fluid in canister 15 is indicative of a swallowing disorder . that is , if a patient has a swallowing disorder , then the tracer deposited on his / her tongue would travel into the trachea and collect in the superior region 13 a above the cuff . thus , upon detection of tracer from the fluids of the superior region , the presence of a swallowing disorder is identified . the inventive method is a significant improvement over the prior art procedure . for example , the method does not require that a patient ingest foods and it does not require that the tracer travel all the way to the inferior region to be collected . rather , to the extent that fluid enters the trachea , it will gather in the superior ( subglottic ) region and it will not move farther down the trachea . thus , the inventive method is an objective test that is safe , highly accurate and well tolerated by patients . having described this invention with regard to specific embodiments , it is to be understood that the description is not meant as a limitation since further modifications and variations may be apparent or may suggest themselves to those skilled in the art . it is intended that the present application cover all such modifications and variations .
the invention provides a save and non - invasive alternative to the traditional modified evans blue dye test for dysphagia in intubated patients . the method employs direct application of dye to the tongue , in combination with a tracheal tube that provides suction in the subglottal region above the cuff . by keeping the cuff inflated , the aspiration of food and liquid , as used in the traditional test , is avoided entirely .