we describe a novel nasogastric tube introducer device ( fig1 , 3 , 4 , 8a , 8b , 9a , 9b , 9c , 10a , 10b , 10c , 10d , 11a , 11b and 11c ) comprising guide means in order to guide the nasogastric tube into a subject , the guide means comprising a longitudinal hollow conduit having a peripheral wall defining a passageway therethrough extending from a first / proximal end to a second / distal end . when used , the second / distal end of the device is inserted into the nasal cavity of a patient and the first / proximal end remains outside the nose . the device is manoeuvred as it is inserted in order for the distal end to locate in the gastrointestinal tract . a nasogastric tube can then be relatively easily passed through the conduit to the stomach . preferably the conduit is curvilinear comprising a unique “ s ” shaped curvature ( see for example , fig1 , 3 , 4 # 6 ; 9 a ) that conforms to the anatomy of the nasopharynx area , the design being based on nasal passage profiles from patient ct scans . the curvature improves steering of the nasogastric tube towards the gastrointestinal tract . the shape of the device generates gentle torque that guides the insertion to land in the hypopharynx in optimal position for esophageal cannulation , giving the device a predictable landing zone in the esophagus . preferably the conduit has a posteriorly directed second / distal end ( fig1 # 7 , 9 a ). such a curvature further assists to guide the nasogastric tube away from the trachea towards the esophagus which is posterior to the larynx and reduces the chance of tracheal cannulation . a combination of the anatomically conforming curvilinear form and semi - rigid but flexible material reduces the likelihood of multiple nasogastric tube insertion attempts and results in a procedure that is less time - consuming than when x - rays are used for monitoring positioning . in a preferred embodiment , the nasogastric tube introducer device further comprises an alarm member mounted at the first / proximal end . the alarm member may be detachably mounted . in view of hygiene concerns , a disposable alarm would be favoured . in order to be more certain that the device is not misaligned in the trachea , the alarm member is attached to the first / proximal end of the device and works on the basis of air passing through the trachea to provide an indication whether the nasogastric tube is correctly positioned in the gastrointestinal tract or is misplaced in the lung of said subject . the auditory feedback mechanism produces a characteristic warning sound should cannulation of the trachea occur . this sound is not produced if the esophagus is successfully cannulated . an example of a suitable alarm is the disposable baam ® beck airway airflow monitor device ( great plains ballistics , lubbock , tex ., usa ). the conduit preferably has a posteriorly directed round bevelled tip at the second / distal end ( fig1 # 2 ; 9 a , 9 b , 9 c ; 11 a , 11 b ). bevelling the tip improves air flow through the conduit for more effective triggering of the alarm member . the skilled person will appreciate that there may be several ways in which a nasogastric tube introducer device can be manufactured . one suitable method is by the use of 3d printing ; another is by extrusion . in a preferred embodiment of the invention , the nasogastric tube introducer device is comprised of a semi - rigid material and may have an elliptical cross - sectional profile . an elliptical profile provides an advantage because it more closely matches the elliptical shape of the inlet to the esophagus . it may be made of any suitable medical grade material such as plastic , polymers , latex , silicon or the like . preferably the device is engineered in a moderately stiff yet flexible silicone which confers steerability and a predictable landing at the desired target zone without overt discomfort to the patient . an example of a suitable silicone is nusil med - 4080 hcr ( nusil technology llc , ca 93013 usa ). the last two digits refer to the silicone hardness ( durometer , type a 80 , astm d2240 ). the tip of the posteriorly curved second / distal end ( fig9 a ; 11 a and 11 b ) is preferably comprised of a softer more compliant material to prevent mucosal injury . the compliant material may be silicone and an example of a suitable silicone is nusil med - 4930 ( nusil technology llc , ca 93013 usa ). the last two digits refer to the silicone hardness ( durometer , type a 30 , astm d2240 ). in a preferred embodiment , the nasogastric tube introducer device is coated on the inner ( luminal ) surface with a coating that reduces friction and can tolerate sterilization . an example of a suitable coating is nusil med - 6670 ( nusil technology llc , ca 93013 usa ). the last two digits refer to the silicone hardness ( durometer , type a 70 , astm d2240 ). preferably , the outer surface of the nasogastric tube introducer device is coated with a substance that reduces friction and can tolerate sterilization . an example of a suitable coating is a combination of nusil med - 6670 ( nusil technology llc , ca 93013 usa ) and parylene ( parylene coatings services , inc , tex . 77494 usa ). the alarm member may be composed of various suitable compounds , such as plastic and / or polymers and could be complex or simple in operation and readout . a simple version of the alarm member is whistle - like ( fig1 ; # 1 ), such as the disposable baam ® beck airway airflow monitor device ( great plains ballistics , lubbock , tex ., usa ). a more complex alarm may be digital . the alarm may produce a distinct sound corresponding to the bidirectional airflow in the trachea of the subject ; wherein an audible signal indicates tracheal cannulation . the conduit preferably has a handle located at or near the first end ( fig1 # 4 ; 9 c ; 10 a , 10 b , 10 c and 10 d ). the ergonomic handle provides the user with more control over the device during insertion and positioning and prevents the proximal end from entering the nasal cavity . preferably , the conduit comprises a longitudinal slit ( see for example fig1 # 5 ), preferably in the form of a “ v - groove ” ( see for example , fig8 a , 8b and 10d ) defined in the peripheral wall of the conduit to enable the nasogastric tube to be moved out of the passageway defined by the conduit and separate the guide from the nasogastric tube . the purpose of this is to allow removal of the device from the subject without disturbing the nasogastric tube . the slit may be sealed in some way to prevent the nasogastric tube from inadvertently becoming dislodged from the device during the insertion and location procedure . preferably , the longitudinal slit comprises a tear - away mechanism to allow removal of the introducer once the ngt has passed through its hollow conduit into the esophagus ( fig8 a , 8b ; 10 d ). in a preferred embodiment the handle is configured to help the user insert and peel the guide with ease ( fig1 a , 10b , 10c and 10d ). it preferably has a curved design that allows placement of a thumb on either side to initiate the tearing of the guide to release it from the ngt . the skilled person would understand that other means for removing the device while leaving the nasogastric tube undisturbed in situ may be possible without deviating from the present invention . the conduit of the nasogastric tube introducer device may also comprise guide and / or depth markings ( fig1 # 9 ) and / or a reflective longitudinal line ( fig1 ; # 3 ). these markings assist the user to determine the position of the device within the nasal cavity , throat and esophagus during the insertion procedure . a reflective longitudinal line may help orientate the user as to which side should be facing upwards or downwards during the insertion . preferably the conduit is configured in shape and length so that its distal end is advanced to its position of intended use in the hypopharynx just above the cricopharyngeus muscle and enter the esophagus , to allow the ngt to be passed into the esophagus and reach the stomach . in a preferred embodiment , the device is manufactured using extrusion methods and the device is comprised of the following materials obtainable from nusil technology llc , ca 93013 usa and parylene coatings services , inc , texas 77494 usa : material for the guide : med - 4080 hcr ( durometer , type a 80 , astm d2240 ); material for the distal tip : med - 4930 ( durometer , type a 30 , astm d2240 ); material for the handle : med - 4950 lsr ( durometer , type a 50 , astm d2240 ); material for the over mold : med - 4950 lsr ( durometer , type a 50 , astm d2240 ); coating of inner surface : med 6670 ( durometer , type a 70 , astm d2240 ); coating of outer surface : med 6670 / parylene . an advantage of the present invention is that nurses would be incentivized to adopt this product because they could overcome the practical difficulties faced during insertion of nasogastric tubes , like coiling and poor maneuverability etc ., hence saving precious time . the present invention is suitable for stroke patients , elderly and the disabled with difficulty in swallowing . it should be best deployed in an inpatient setting , community hospitals or nursing homes . the nasogastric tube introducer device of the invention may be manufactured by 3d printing or by extrusion methods . in a preferred embodiment of the invention , the nasogastric tube introducer device is made from silicone by extrusion . the silicone extrusion process begins with blending a two - part silicone gumstock on a two - roll mill to produce a homogeneous medical - grade silicone . the silicone was then formed into strips and fed continuously into the extruder . once the required shape was acheived the medical grade tubing was passed through an oven to cure the product with radiant heat . for the device described herein a “ form fixture ” and “ over molds ” were developed to form and mold components . also , the soft tip was made as a separate mold and then fused together . suitable silicone material for the guide may be med - 4080 hcr ( high consistency rubber ) ( nusil technology llc , ca 93013 usa ) a two - part , high durometer ( type a 80 , astm d2240 ), tear resistant silicone elastomer . suitable material for the over mold and / or handle may be med - 4950 lsr ( liquid silicone rubber ) ( nusil technology llc , ca 93013 usa ), a two - part , translucent silicone system ( durometer , type a 50 , astm d2240 ) used with injection molding equipment . the inner surface of the silicone guide may be coated to decrease the coefficient of friction ( cof ) compared to the uncoated silicone and increase abrasion resistance . a suitable coating for the inner surface of the invention may be med 6670 ( nusil technology llc , ca 93013 usa ), a two - part silicone elastomer ( durometer , type a 70 , astm d2240 ) dispersed in xylene . the outer surface of the guide may also be coated with a protective polymeric substance . a suitable outer coating is known as parylene ( parylene coatings services , inc , texas 77494 usa ). a more preferred outer coating comprises a mixture of parylene and med 6670 . bedside clinical tests like the “ whoosh test ” and ph test have long been established to be inadequate for placement confirmation [ farrington m ., et al ., pediatr nurs 35 ( 1 ): 17 - 24 ( 2009 )]. the cxr is at present the most routinely used method to confirm placement inpatient , usually in combination with the previous tests . however , incidence of misplacement remains at 3 . 2 %, and reported deaths resulting from missed airway intubation are at 0 . 5 % [ de aguilar - nascimento , j . e . & amp ; kudsk , k . a . jpen j parenter enteral nutr 31 : 269 - 273 ( 2007 )]. colorimetry ( rightspot ) has not been formally trialled for safety and carries the risk of false negatives due to concurrent acid secretion or inability to aspirate gastric contents ( e . g . on an empty stomach , or a tube &# 39 ; s exit holes are against the stomach wall ) electromagnetic - guided placement ( cortrak ) is claimed to provide bedside direct visualization during ngt insertion , but it is costly and studies document success rates of only 80 %. in addition there have been 21 adverse events reported to the us fda manufacturer and user facility device experience ( maude ) database . ( conventional ) endoscopic placement of ngts allows direct visualization of the ngt in the esophagus but is costly , time - consuming and requires the expertise of a trained specialist . this method is reserved for patients with distorted anatomy , for example , by obstruction from a tumour . the iris system is essentially the same as endoscopic ngt placement without the steerability of an endoscope and shares the same problems of cost , time and requirement of specialist presence . capnography ( co2nfirm ) claims to provide immediate feedback but remains a somewhat costly option and also does not reliably rule out airway intubation [ melody ni et al ., emj gastroenterol 3 : 49 - 56 ( 2014 )]. the benefits or advantages of the present invention over other currently known methods were determined in a comparative study and are set out in table 2 .
we describe a nasogastric tube introducer device to assist medical practitioners and others in the medical field with the insertion of a nasogastric tube to facilitate feeding and / or administration of oral medications to patients in need thereof .