Patent Publication Number: US-2022233407-A1

Title: Method and Apparatus for Assisting, Checking, and Confirming Nasogastric and Orogastric Tube Insertion and Placement

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. patent application Ser. No. 17/331,966, filed May 27, 2021, which claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 63/102,081, filed May 27, 2020, which is entitled, “Long Flexible Structure for Confirming Placement of an NG Tube in the Stomach” and which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to nasogastric and orogastric tubes and the insertion and placement thereof. More particularly, disclosed herein is an apparatus for assisting a nasogastric or orogastric tube in traversing the tortuous terrain from the nose or mouth of a subject to the stomach and in checking whether a compromise, such as a bend, a kink, a twist, a coil, or a loop, has been formed in the tube during the insertion and, if not, confirming whether the distal portion of the tube is indeed inside the stomach. 
     BACKGROUND OF THE INVENTION 
     Nasogastric and orogastric tubes are tools used in medicine for diagnostic and therapeutic purposes, such as the removal of contents from the stomach, including air, small solid objects, and fluids such as poison, to decompress the stomach, and to put substances directly into the stomach, including nutrients and medicines when a person cannot take food or drink by mouth. 
     Nasogastric or orogastric intubation is a medical procedure involving the blind insertion of an extremely flexible tube through the nose or mouth of a mammal, down the roughly 90-degree turn at the back of the mouth, through the pharynx, through the esophagus, and into the stomach or upper small intestinal tract. The diameter, length, and tortuousness of the terrain to be traversed play a major role in how problematic and challenging the insertion attempt will be in humans and other mammals. 
     Nasogastric and orogastric tubes are typically made of synthetic rubber or nonreinforced polymer plastic materials. They are, therefore, prone to veering off track or becoming compromised somewhere inside a person during and after insertion. A further challenge with nasogastric and orogastric tubes is that, since the lower end of the tubes are blindly inserted in and beyond the nose or mouth of a subject, there is no way for the user to know if and when the lower end of the tube has reached its intended destination. 
     In view of the capacity for nasogastric and orogastric tubes to be placed incorrectly and the potentially dangerous repercussions thereof, it is commonly necessary under present practices to use x-ray imaging to confirm the placement of gastric tubes after insertion. However, the use of x-rays is not without its own problems. While chest x-ray imaging is often considered the ‘gold standard’ for verifying gastric tube placement, serious complications, including death, can derive from misinterpretations and limitations of the imaging. More particularly, the difficulty or inability of x-ray imaging to visualize the exact location and positioning of the tip or bottom opening of the gastric tube significantly contributes to the risk of misinterpretation and resulting complication. 
     Sources indicate that, from 2005 and 2011, the NPSA was notified of approximately 21 deaths and 79 cases of harm due to misplaced nasogastric tubes. Indeed, it has been reported that, between 2005 and 2010, approximately 45% of all cases reported by the National Patient Safety Agency (NPSA) of harm resulting from misplaced gastric tubes were due to misinterpreted chest x-rays. 
     While the harm arising from the misinterpretation of nasogastric tube placement on chest x-rays has been identified by the Department of Health as a “never event,” meaning it should be entirely avoidable, the inability to identify the exact location of the tip of a nasogastric tube and the eyelet opening or openings therein on a chest x-ray remains a major reason for misinterpretation. Such elements often become ‘burned out’ or darkened from the radiation due to their compositions or lack thereof. Furthermore, electrocardiogram leads and other medical wires and tubing on and inside the chest cavity of a person are shown on x-ray imaging and make interpretation even more difficult. Typically being formed of plastic or rubber, nasogastric and orogastric tubes add to the difficulty of their x-ray visualization since radiation passes without resistance through them thereby darkening their appearances on the image. 
     It is apparent, therefore, that there is a real need for a faster, more economical, and less harmful way by which the insertion of a nasogastric or orogastric tube can be accomplished and confirmed. Indeed, numerous articles have been written regarding the risks and difficulties inherent in placing nasogastric and orogastric tubes. Particularly since the individuals that need such tubes are in or are approaching a crisis situation, it is vital in the medical field to have available an apparatus that can assist in, detect, and confirm the placement of nasogastric and orogastric tubes effectively, efficiently, without high costs, and with a minimized risk of harm to the patient. 
     SUMMARY OF THE INVENTION 
     The composition of a nasogastric and orogastric tube makes them extremely vulnerable and prone to deviate off course or otherwise to become compromised during insertion when they encounter the standard anatomical friction or resistance points as they pass through the nose or mouth and into the stomach. The lower ends of nasogastric and orogastric tubes lead the way during insertion, and those lower ends may veer off course or become compromised when they cannot overcome an encounter with the standard anatomical friction or resistance points along the insertion path. Veering off course when the lower end cannot overcome an encounter means following the path of least resistance. Too often, that path leads into a lung due to the proximity of the larynx and the esophagus. In other circumstances, the tube may become compromised when the lower end cannot overcome an encounter or veers off course such that the lower end surrenders to losing its integrity and bends, kinks, twists, coils, or loops thereby rendering the tube useless. 
     With a knowledge of the foregoing, the present inventor has appreciated that the lower ends of nasogastric and orogastric tubes would be assisted by added firmness sufficient during insertion to assist the lower end in overcoming the tube&#39;s tendency to deviate or compromise upon encountering the standard points of friction and resistance during insertion while not being rendered so rigid as to risk perforating the tissue walls of, for instance, the esophagus or stomach. 
     The present inventor has further appreciated that all forms of compromise, including bending, kinking, twisting, coiling, and looping, tend to reduce the inner diameter of each lumen of a nasogastric and orogastric tube at the same time, in the same manner, and at the same location. Most, if not all, forms of compromise cause the passageway of a lumen to collapse inwardly, which reduces the effective inner diameter of the lumen. The amount by which the inner diameter of the lumen is reduced depends entirely on the amount or degree of the compromise. Additionally, reducing the effective inner diameter of a lumen of a nasogastric or orogastric tube to a compromised size smaller than the standard or normal diameter slows and limits the flow of fluids therethrough. This can cause severe problems, particularly where there is a great need for the rapid input or removal a large quantity of fluid for survival. 
     The present inventor appreciated that reducing the effective inner diameter of a lumen of a nasogastric or orogastric tube to a compromised size smaller than the diameter of a solid object within the lumen causes the passageway of the lumen to shrink down and pinch or squeeze tightly on the solid object therewithin. Restrictive force may be applied to the object sufficient to prevent a user from being able to move the object beyond the reduction, at least not without significant resistance without obstruction. Additionally, reducing the effective inner diameter of a lumen of a nasogastric or orogastric tube to a compromised size smaller than the diameter of a solid object prior to attempting to pass the object through the lumen will tend to prevent a user from being able to cause the solid object to travel through or past the reduction. 
     In view of the dangers, limitations, and potential complications deriving from nasogastric or orogastric tubes of the prior art, a goal of the present invention is to provide a method and apparatus capable of assisting the lower end of a nasogastric or orogastric tube in overcoming the tendency of such tubes to deviate or collapse when encountering points of anatomical friction or resistance during insertion. 
     A further goal of the present invention is to provide a method and apparatus that enable a user to verify whether the lumen of a nasogastric or orogastric tube is obstructed or has otherwise become compromised, such as during or after the insertion process. 
     Another goal of the present invention to provide a method and apparatus capable of confirming whether the lower end of a nasogastric or orogastric tube is successfully positioned in the stomach. 
     In certain embodiments of the invention, a further object is to provide a method and apparatus that facilitates the x-ray visualization to check and confirm the placement of a nasogastric and orogastric tube within a patient and, potentially, the location of the opening or openings in the gastric tube with respect to the patient. 
     A related object of such embodiments of the invention is to prevent the misinterpretation of x-ray imaging of nasogastric and orogastric tubes within patients thereby to facilitate effective placement and to minimize the possibility of severe complications, including death, from incorrect placement. 
     A further related object of the invention is to enable the placement and usage of nasogastric and orogastric tubes without uncertainty or doubt as to the placement of the distal portion of the tubes. 
     Another object of embodiments of the invention is to provide an apparatus for assisting in verifying and determining the placement of nasograstric and orogastric tubes that can be readily distinguished and recognized in relation to other articles, including medical wires and leads. 
     A further object of embodiments of the invention is to provide an apparatus for assisting in verifying and determining the placement of nasogastric and orogastric tubes that enables a differentiation between openings in a gastric tube and a dimensioning and determination of locations of aspects of the apparatus and the gastric tube in which it is placed, including the distal end, openings, and other locations of the gastric tube. 
     These and further objects and advantages of embodiments of the present invention will become obvious not only to one who reviews the present specification and drawing but also to those who have an opportunity to experience embodiments of the method and apparatus disclosed herein in operation. It will be appreciated that, although the accomplishment of each of the foregoing objects in a single embodiment of the invention may be possible and indeed preferred, not all embodiments will seek or need to accomplish each and every potential advantage and function. Nonetheless, all such embodiments should be considered within the scope of the present invention. 
     In one manifestation, the invention can be characterized as an apparatus for assisting in the placement of a distal portion of a lumen of a gastric tube, such as a nasogastric tube or an orogastric tube, in a stomach of a mammal. In this context, reference to assisting should be interpreted to include assisting, checking, and confirming nasogastric and orogastric tube insertion and placement. The apparatus can be considered to be founded on an elongate body portion of flexible material with a proximal end and a distal end. By way of non-limiting example, the body portion can take the form of an elongate core surrounded by a sheath. A handle portion is fixed to the proximal end of the body portion. The handle portion has a width. In certain practices of the invention, the width of the handle portion can be equal to or greater than a width of the body portion, although other dimensional relationships are possible. A distal tip portion is fixed to the distal end of the body portion, whether by being integrally formed therewith or as a separate member coupled thereto. The body portion and the distal tip portion together form a long, thin, flexible structure with a length for being selectively received into a passageway of a lumen of the gastric tube. Under such constructions, an ability to insert the body portion and the distal tip portion into the passageway in the lumen of the gastric tube over the length of the long, thin, flexible structure provides a positive indication that the lumen is not blocked, obstructed, or otherwise compromised over the length of the long, thin, flexible structure. 
     In embodiments of the apparatus, the distal tip portion of the apparatus has rigidity sufficient, when received into the distal portion of the lumen of the gastric tube, to facilitate passage of the distal portion of the lumen during insertion into the mammal. Also according to embodiments of the invention, the body portion and the distal tip portion of the apparatus can have lateral dimensions sufficient to prevent passage of the body portion and the distal tip portion past a blockage, obstruction, or other compromise in the lumen of the gastric tube. Also as disclosed herein, the body portion and the distal tip portion of the apparatus can have lateral dimensions sufficient to prevent retraction of the body portion and the distal tip portion when the body portion and the distal tip have been received into the lumen of the gastric tube and a compromise develops in the lumen of the gastric tube at a location along the length of the long, thin, flexible structure. 
     In certain embodiments, a pH indicator sensor array is retained by the long, thin, flexible structure formed by the body portion and the distal tip portion. The pH indicator sensor array comprises at least a first pH indicator sensor with a pH indicator. The first pH indicator sensor is calibrated to exhibit a verifiable color change in response to contact with a predetermined subject fluid, such as gastric fluid, lung fluid, or another fluid. 
     It is further disclosed herein that the pH indicator sensor array can additionally comprise a second pH indicator sensor with a pH indicator calibrated to exhibit a verifiable color change in response to contact with a predetermined subject fluid. The first and second pH indicator sensors can, for instance, be calibrated to exhibit a verifiable color change in response to contact with the same predetermined subject fluid. In other embodiments, the first and second pH indicator sensors can be calibrated to exhibit a verifiable color change in response to contact with different predetermined subject fluids, such as with the first pH indicator sensor calibrated to exhibit a verifiable color change in response to contact with gastric fluid and the second pH indicator sensor calibrated to exhibit a verifiable color change in response to contact with lung fluid. 
     Still further, the pH indicator sensor array retained by the long, thin flexible structure can comprise a plurality of pH indicator sensors, each with a pH indicator calibrated to exhibit a verifiable color change in response to contact with a predetermined subject fluid. The plurality of pH indicator sensors can be longitudinally spaced along the long, thin, flexible structure to facilitate alignment of the sensors with eyelet openings disposed in the distal portion of the lumen of the gastric tube. 
     The apparatus can further include measurement markings disposed along the long, thin, flexible structure. For example, measurement markings can be disposed to descend along the long, thin, flexible structure from a highest number disposed adjacent to the proximal end of the body portion. Under such constructions, the measurement markings can facilitate a determination of a longitudinal location of a blockage, obstruction, or other compromise of the gastric tube inside the mammal. 
     In certain practices of the invention, at least one notch can be disposed in the long, thin, flexible structure. The at least one notch demonstrates decreased resistance to flexion in comparison to segments of the long, thin, flexible structure disposed adjacent to the notch. In this regard, it is noted that, when an inserted gastric tube has coiled or looped inside a patient, the tube will have one or more curves therein with a potential reduction in the inner diameter thereof. The reduction in the inner diameter is dependent on the degree of curvature. The at least one notch in the long, thin, flexible medical structure is useful for addressing this type of compromise in that, when the notch in the device starts to enter the curve, the notch flexes while the portions of the device adjacent to the notch resist bending and curving. The portion of the device prior to the notch will thus resist traversing or moving through the curved portion of the tube and will indicate to the practitioner that a compromise has developed, which will prompt the practitioner to remove the tube. 
     Also as disclosed herein, at least one longitudinal or lateral reinforcing rib can be disposed on the long, thin, flexible structure. The reinforcing rib is operative to increase the local thickness and rigidity of the long, thin, flexible structure. In a manner similar to the effect of the notch in the device, the rib will limit the localized tendency of the long, thin, flexible device to bend or curve to conform to a curved or bent compromise in the gastric tube. The portion of the device with such a rub will thus resist traversing or moving through the curved portion of the tube and will indicate to the practitioner that a compromise has developed. This indication will prompt the practitioner to remove the tube. 
     Embodiments of the invention can alternatively be characterized as a kit for assisting in a placement of a distal portion of a lumen of a gastric tube in a stomach of a mammal. The kit comprises a gastric tube comprising a lumen with an entrance, a passageway, and a distal portion and a long, thin, flexible medical apparatus. The apparatus is again founded on an elongate body portion of flexible material with a proximal end and a distal end. A handle portion is fixed to the proximal end of the body portion. The handle portion has a width greater than a width of the body portion. A distal tip portion is fixed to the distal end of the body portion, and the body portion and the distal tip portion together form a long, thin, flexible structure with a length for being selectively received into a passageway of a lumen of the gastric tube. With such a kit provided, an ability to insert the body portion and the distal tip portion into the passageway in the lumen of the gastric tube over the length of the long, thin, flexible structure provides a positive indication that the lumen is not blocked, obstructed, or otherwise compromised over the length of the long, thin, flexible structure. 
     In certain embodiments of the kit, a pH indicator sensor array can be retained by the long, thin flexible structure. That array could comprise a single sensor, or it may comprise a plurality of pH indicator sensors, each with a pH indicator calibrated to exhibit a verifiable color change in response to contact with a predetermined subject fluid. For instance, the plurality of pH indicator sensors can be longitudinally spaced along the long, thin, flexible structure. Moreover, the distal portion of the lumen of the gastric tube can have a plurality of apertures spaced therealong. The plurality of pH indicator sensors of the pH indicator sensor array can be disposed to align with the plurality of apertures in the distal portion of the gastric tube when the long, thin, flexible structure is inserted into the lumen of the gastric tube. 
     The passageway of the lumen of the gastric tube has a length, and the length of the long, thin, flexible structure formed by the body portion and the distal tip portion in certain embodiments of the apparatus does not exceed the length of the passageway of the lumen. In certain examples, for instance, the length of the long, thin, flexible structure formed by the body portion and the distal tip portion is approximately equal to the length of the passageway of the lumen. As used herein, approximately equal should be interpreted to include the long, thin, flexible structure being equal in length to the length of the passageway of the lumen or within an insubstantial margin longer or shorter than the length of the passageway. 
     In particular embodiments of the apparatus, the length of the long, thin, flexible structure formed by the body portion and the distal tip portion could be greater than the length of the passageway of the lumen in which it is to be inserted. In such practices of the invention and while recognizing that it could be greater in lateral dimension, the handle portion could, again by way of example and not limitation, be equal or perhaps even smaller in lateral dimension as compared to the lateral dimension of the body portion since the apparatus could not fall inside the lumen to become irretrievable, trapped, or stuck inside the lumen. Although not excluded from the scope of the claims except where expressly stated, the length of the long, thin, flexible structure formed by the body portion and the distal tip portion will preferably not be substantially less than the length of the passageway of the lumen in which it is to be inserted. Where the length of the long, thin, flexible structure formed by the body portion and the distal tip portion is longer than the length of the passageway of the lumen, the body portion and the distal tip portion will preferably have a measurement scale with numbering descending from the proximal end of the body portion along the long, thin, flexible structure. With such a measurement scale provided, a user can be apprised of when the actual length of the passageway of the lumen has been traversed. Once the actual length of the passageway of the lumen has been traversed, the user can cease further insertion knowing that the distal tip portion and the body portion have travelled sufficient distance to prove there is not blockage, obstruction, or other compromise in the lumen. 
     Recognizing that nasogastric and orogastric tubes come in various lengths, typically ranging from 6 inches to 6 feet, a single long, thin, flexible medical device according to the invention may, for reasons of economy or otherwise, have a length that subsumes the range of the lengths of typical NG tubes and their lumens. The long, thin, flexible medical device can have measurement indicators, such numbering, color coding, or any other marking indicators or combinations thereof, that denote various lengths indicating a depth of insertion corresponding to known lengths of different gastric tube lumens. For instance, the device may have a marker indicative of a 12-inch lumen length and further markers indicative of 18-inch, 24-inch, and other predetermined lumen lengths. With this, an ability to insert the device up to the 12-inch lumen length marking indicator in a gastric tube known to have a 12-inch lumen length will provide a positive indication that the tube is not blocked or otherwise compromised. Moreover, using such a concept, a manufacturer could produce a long, thin, flexible medical device in a single length to fit most or even all possible lengths of nasogastric and orogastric tubes. In use, a practitioner would merely be required to identify the marking indicator on the device corresponding to the selected gastric tube lumen length and determine whether that length of the device can be inserted into and removed from the gastric tube without obstruction while the gastric tube is in place within the patient. 
     Practices of the invention can be characterized still further as a method for assisting in a placement of a distal portion of a lumen of a gastric tube in a stomach of a mammal. The method includes providing a gastric tube comprising a lumen with an entrance, a passageway, and a distal portion and providing a long, thin, flexible medical apparatus. The long, thin, flexible medical apparatus comprises an elongate body portion of flexible material, a handle portion fixed to a proximal end of the body portion, and a distal tip portion fixed to a distal end of the body portion. The body portion and the distal tip portion together form a long, thin, flexible structure with a length for being selectively received into a passageway of a lumen of the gastric tube. The method further comprises inserting the lumen of the gastric tube into the mammal. Then, one can determine whether the distal portion of the lumen of the gastric tube is placed without blockage, obstruction, or other compromise in the stomach of the mammal based on an insertion of the long, thin, flexible structure into the lumen of the gastric tube. 
     The step of determining whether the distal portion of the lumen of the gastric tube is placed without blockage, obstruction, or other compromise in the stomach of the mammal can, in certain practices, comprise determining whether the long, thin, flexible structure is capable of being fully received into the lumen of the gastric tube without restriction by blockage, obstruction, or other compromise. In further practices of the method, the step of determining whether the distal portion of the lumen of the gastric tube is placed without blockage, obstruction, or other compromise in the stomach of the mammal can be carried out by determining whether the long, thin, flexible structure when received into the lumen of the gastric tube can be advanced or retracted without restriction by blockage, obstruction, or other compromise. 
     In other practices of the method, a pH indicator sensor array is retained by the long, thin, flexible structure formed by the body portion and the distal tip portion. The pH indicator sensor array comprises a first pH indicator sensor with a pH indicator calibrated to exhibit a verifiable response to contact with a predetermined subject fluid. In such practices of the method, the step of determining whether the distal portion of the lumen of the gastric tube is placed in the stomach of the mammal comprises determining whether the pH indicator exhibits the verifiable response. 
     It is still further disclosed herein that the pH indicator sensor array retained by the long, thin flexible structure can include a second pH indicator sensor with a pH indicator calibrated to exhibit a verifiable color change in response to contact with a predetermined subject fluid. For instance, the first and second pH indicator sensors can be calibrated to exhibit a verifiable color change in response to contact with different predetermined subject fluids, such as with the first pH indicator sensor calibrated to exhibit a verifiable color change in response to contact with gastric fluid and the second pH indicator sensor calibrated to exhibit a verifiable color change in response to a bodily fluid other than gastric fluid, such as but not limited to lung fluid. 
     Also as disclosed herein, measurement markings defining longitudinal distances along the device can be disposed along the long, thin, flexible structure. In such embodiments, the step of determining whether the distal portion of the lumen of the gastric tube is placed without blockage, obstruction, or compromise in the stomach of the mammal based on an insertion of the long, thin, flexible structure at least partially into the lumen of the gastric tube includes determining a location of a blockage, obstruction, or compromise in the gastric tube based on the measurement markings disposed along the long, thin, flexible structure. 
     Recognizing the limitations of x-ray imaging in seeking to confirm NG tube placement and the risks relating thereto, embodiments of the long, thin, flexible medical apparatus are disclosed for enabling the radiographic determination of the placement of a distal portion of a lumen of a gastric tube in a stomach of a mammal. In one such embodiment, the apparatus comprises an elongate body portion of flexible material with a proximal end and a distal end. A handle portion is fixed to the proximal end of the body portion and a distal tip portion is fixed to the distal end of the body portion. The body portion and the distal tip portion together form a long, thin, flexible structure with a length for being selectively received into a passageway of a lumen of the gastric tube. A radiopaque marker is retained by the distal tip portion of the apparatus. 
     Under such constructions, a location of the radiopaque marker can be visualized by x-ray imaging. Moreover, a location of the distal tip portion of the apparatus can be ascertained based on the location of the radiopaque marker. Most importantly, a location of distal portion of the lumen of the gastric tube in which the distal tip portion of the apparatus is received can be determined with certainty based on the location of the distal tip portion that was determined based on the location of the radiographic marker. 
     In certain embodiments, at least first and second radiopaque markers are retained in longitudinally spaced relation by the distal tip portion of the apparatus. The first and second radiopaque markers are preferably distinct from one another in at least one of size and shape. In practices of the invention, the first and second radiopaque markers are coded based on their longitudinal positions relative to the distal tip portion of the apparatus. For example, the first and second radiopaque markers can be coded by a number of protuberances comprising the respective radiopaque marker, such as by having a single protuberance indicative of a first longitudinal position and first and second protuberances indicative of a second longitudinal position. 
     Numerous different types of protuberances or other shapes are possible within the scope of the invention. In one example, the first radiopaque marker comprises a single ring indicative of the first longitudinal position while the second radiopaque marker comprises first and second rings indicative of the second longitudinal position. As taught herein, the first longitudinal position can be spaced from a distal end of the distal tip portion by a distance D 1 , and the second longitudinal position can be spaced from the first longitudinal position by a distance D 2  and from the distal end of the distal tip portion by the combined distances D 1  and D 2 . 
     Third and perhaps further radiopaque markers can be retained. Where a third radiopaque marker is provided, it can be coded with a code indicative of a third longitudinal position relative to the distal tip portion. The third longitudinal position may, for example, be spaced from the second longitudinal position by a distance D 3  and from the distal end of the distal tip portion by the combined distances D 1 , D 2 , and D 3 . Still further, embodiments are disclosed wherein a radiopaque marker is retained substantially coincident with a distal end of the distal tip portion, such as by being fixed to the distal end of the distal tip portion, by surrounding the distal end of the distal tip portion, or by forming the distal end of the distal tip portion. 
     In embodiments of the apparatus, the first and second radiopaque markers are coded by differentiating patterns of radiopaque material. In other embodiments, the first and second radiopaque markers are coded with radiopaque material representative of numerical characters, such as Roman numerals or numbers. The numerical characters can, for instance, be disposed in repeating series circumferentially spaced over the distal tip portion at the respective longitudinal position. 
     Still further, it is disclosed herein that the apparatus can be adapted for enabling the radiographic determination of the placement of a distal portion of a lumen of a gastric tube with an opening therein. The radiopaque marker retained by the distal tip portion of the apparatus can be positioned on the distal tip portion to align substantially with the opening in the lumen of the gastric tube when the apparatus is received in the gastric tube. With that, the location of the opening can be ascertained based on an x-ray visualization of the radiopaque marker. 
     Even further, embodiments of the apparatus as disclosed herein are adapted for enabling the radiographic determination of the placement of a distal portion of a lumen of a gastric tube with first, second, and third longitudinally spaced openings therein. In such practices, first, second, and third radiopaque markers are retained in longitudinally spaced relation by the distal tip portion of the apparatus in respective correspondence to the first, second, and third longitudinally spaced openings of the gastric tube. The markers align substantially with the openings in the lumen of the gastric tube when the apparatus is received in the gastric tube. With that, locations of the radiopaque markers can be visualized by x-ray imaging, and locations of the openings in the lumen of the gastric tube can be ascertained based on the locations of the radiopaque markers. 
     Embodiments of the invention can further be characterized as a kit for enabling the radiographic determination of the placement of a distal portion of a lumen of a gastric tube in a stomach of a mammal. In one embodiment, the kit comprises a gastric tube with a lumen with an entrance, a passageway, and a distal portion and a long, thin, flexible medical apparatus as disclosed with an elongate body portion, a handle portion fixed to the proximal end of the body portion, a distal tip portion fixed to the distal end of the body portion, and a radiopaque marker retained by the distal tip portion of the apparatus. A practitioner practicing a method for using the kit can visualize a location of the radiopaque marker by x-ray imaging. Based on that visualization, the practitioner can ascertain a location of the distal tip portion of the apparatus. Still further, based on the location of the distal tip portion, a location of distal portion of the lumen of the gastric tube with the distal tip portion of the apparatus received therein can be determined with certainty. 
     Furthermore, by use of embodiments of the kit wherein first and second radiopaque markers are retained in longitudinally spaced relation by the distal tip portion of the apparatus, a practitioner can determine with certainty the location and orientation of the distal tip portion of the apparatus and, based thereon, the location and orientation of the distal portion of the lumen of the gastric tube. Still further, where radiopaque markers are coded and distinctly shaped relative to one another, a practitioner may be enabled to determine the location and orientation of the entire distal tip portion of the apparatus and the distal portion of the gastric tube based on a visualization of the location and orientation of even a single one of the distinctly shaped radiographic markers. Further still, where the radiopaque markers are longitudinally positioned in correspondence to openings in the lumen of the gastric tube, the location of plural openings with known dimensional relationships can be determined based on the visualized location and orientation of one or more of the radiographic markers. 
     One will appreciate that the foregoing discussion broadly outlines the more important goals and certain features of the invention to enable a better understanding of the detailed description that follows and to instill a better appreciation of the inventor&#39;s contribution to the art. Before any particular embodiment or aspect thereof is explained in detail, it must be made clear that the following details of construction and illustrations of inventive concepts are mere examples of the many possible manifestations of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view in front elevation of an embodiment of the apparatus of the present invention wherein pH indicator sensors are disposed in longitudinal alignment along a distal tip portion thereof; 
         FIG. 2  is a partially-sectioned view in front elevation of an embodiment of the apparatus wherein the distal tip portion thereof is tapered; 
         FIG. 3  is a partially-sectioned cross-sectional view of an apparatus according to the invention fully inserted into a secondary lumen; 
         FIG. 4  is a cross-sectional view of an apparatus as disclosed herein fully inserted in a main lumen; 
         FIG. 5  is an amplified cross-sectional view of an apparatus according to the invention disposed within a secondary lumen with gastric fluid making contact with the pH indicator sensors of the apparatus; 
         FIG. 6  is an amplified cross-sectional view of an apparatus according to the present invention with gastric fluid making contact with pH indicator sensors of the apparatus aligned with eyelet openings of an NG tube; 
         FIG. 7  is a view of an apparatus pursuant to the invention inserted in a secondary lumen of an NG tube placed in a human stomach; 
         FIG. 8  is a view of an apparatus as disclosed herein with the advancement thereof obstructed by a compromise in the NG tube; 
         FIG. 9  is a view of an apparatus as disclosed herein with the retraction thereof prevented by a compromise in the NG tube; 
         FIG. 10  is a view of an apparatus as disclosed herein operating to assist the NG tube during insertion and overcoming friction and resistance points within the NG tube; 
         FIGS. 11, 12, 13, 14, and 15  are views in front elevation of alternative embodiments of the apparatus of the present invention; 
         FIG. 16  is an amplified cross-sectional view of an alternative apparatus according to the invention received into an NG tube wherein unique radiographic markers are retained by the distal tip portion of the apparatus; 
         FIG. 17  is an amplified cross-sectional view of a further alternative apparatus according to the invention received into an NG tube and with unique radiographic markers retained by the distal tip portion of the apparatus; 
         FIG. 18  is an amplified cross-sectional view of another apparatus according to the invention received into an NG tube and with unique radiographic markers retained by the distal tip portion of the apparatus; 
         FIG. 19  is an amplified cross-sectional view of an additional apparatus according to the invention received into an NG tube and with a distal tip radiographic marker retained by the distal tip portion of the apparatus; 
         FIG. 20  is a view in front elevation of an apparatus according to the invention with unique radiographic markers retained by the distal tip portion and with measurement indicators along the body portion thereof denoting a depth of insertion corresponding to possible gastric tube lumen lengths; 
         FIG. 21  is a view in front elevation of another apparatus according to the invention with unique radiographic markers retained by the distal tip portion; and 
         FIG. 22  is a view in front elevation of a further apparatus according to the invention with unique radiographic markers retained by the distal tip portion. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Methods and apparatuses for assisting, checking, and confirming nasogastric and orogastric tube insertion and placement as disclosed herein can pursue a wide variety of embodiments, each within the scope of the invention. However, to ensure that one skilled in the art will be able to understand and, in appropriate cases, practice the present invention, certain preferred embodiments and aspects of the broader invention revealed herein are described below and shown in the accompanying drawing figures. 
     The present invention was made to meet the previously unsolved need for a method and apparatus by which the insertion of a nasogastric or orogastric tube in a subject can be readily assisted, checked, and confirmed in a rapid and efficient manner without a need for x-rays. The methods and apparatuses disclosed herein are at times shown and described with respect to the insertion of a nasogastric or NG tube in the stomach of a person. However, the present invention shall not be considered to be so limited except as may be expressly provided for in the claims. It will be understood, for instance, that the present invention has equal application to orogastric tubes and with respect to all mammals. Collectively, orogastric tubes and nasogastric tubes may be referred to as gastric tubes herein. 
     The structure of a typical NG tube can be further understood with reference to  FIGS. 3 and 4  where the NG tube is indicated generally at  100 . Also in  FIGS. 3 and 4 , an apparatus according to the present invention is selectively received into the NG tube  100  and indicated generally at  10 . 
     Many such NG tubes  100  have two types of lumens: a main lumen  102  and a secondary lumen  104 . The main lumen  102  has a distal or lower end  106  and an entrance aperture  110 . The secondary lumen  104  has an entrance aperture  112 , a proximal portion free of the main lumen  102 , and a distal portion that extends within the main lumen  102 . Lumens  102  and  104  of NG tubes  100  vary in inner and outer diameters, shape, and the length of the passageway therethrough. The main lumen  102  of most nasogastric tubes  100  is called the ‘suction or drainage lumen’ and occupies the largest space of the tube  100 . The distal or lower portion  106  of the main lumen  102  and the NG tube  100  in general typically has multiple eyelet openings  108  for inputting and removing fluids and solid substances relative to the stomach quickly. 
     The secondary lumens  104  of nasogastric tubes  100  are used for many different purposes. The distal portion of the secondary lumen  104  occupies a longitudinal, relatively narrow diameter space of the tube  100 . The distal portion of the secondary lumen  104  has at least one opening  114  to be in fluidic communication with the main lumen  102 . As such, the sidewall of the distal portion of the secondary lumen  104  opens into the passageway of the main lumen  102  of the NG tube  100  within the distal portion  106  of the NG tube  100 . As disclosed herein, the sidewall and the distal portion opening  114  allow fluid that enters the eyelet openings  108  in the distal portion  106  from the outside surroundings to pass. When the apparatus  10  of the present invention is fully inserted into the NG tube  100  with a distal tip portion  16  thereof disposed within the distal portion  106  of the lumen  100 , liquid received into the distal portion  106  of the NG tube  100  will contact the distal tip portion  16  of the present apparatus  10 . 
     As referenced herein, the inner diameter of a lumen  102  or  104  of a nasogastric tube  100  may be considered as the measurement across the inside of the lumen  102  or  104 . That inner diameter of a lumen  102  or  104  is less than the outer diameter of the same lumen  102  or  104 . The inner diameter of the main lumen  102  of most NG tubes  100  is greater than the inner diameter of the secondary lumen  104  of the same tube  100 . In most NG tubes  100 , the main lumen  102  has a larger inner diameter along an upper or proximal and middle passageway and a smaller inner diameter for the lower or distal passageway. In some NG tubes  100 , the main lumen  102  has the same inner diameter at the proximal and middle passageways as in the distal passageway. The inner diameters of the main lumen  102  and the secondary lumen  104  of NG tubes  100  is often not disclosed by the manufacturer. 
     Nasogastric tubes  100  are commonly sized by their outer diameter in “FR” units or “French units”. FR units are a gauge measurement known in the art where one increment on the FR scale is equal to ⅓ of a millimeter. Thus, an 8 FR catheter or nasogastric tube  100  is 8×0.33 mm or 2.64 mm. Typically, standard nasogastric tube outer diameter measurements are 4 FR to 8 FR for the neonatal range, 6 FR to 14 FR for children, and 12 FR to 18 FR for adults. 
     The overall length of a chosen nasogastric tube  100  depends entirely on the subject, whether the person be a newborn, an infant, child, an adolescent, or an adult, with whom it is intended to be used. Typical lengths range from 6 inches to 6 feet. For example, nasogastric tubes  100  with overall lengths from 21.5 to 39 inches are designed for small children, and tubes  100  with overall lengths from 42 to 50 inches are designed for adults. 
     The selection process to determine the length of an NG tube  100  to use for newborns, infants, children, adolescents, and adults is similar and is performed by a standard method of measuring the distance from the tip of the nose of the person, around one ear, and down to just below the left costal margin or region of the individual&#39;s chest. The selection process to determine the outer diameter of an NG tube  100  to use for newborns, infants, children, adolescents and adults is determined by the size of the opening of the nose of the person into whom the tube is to be inserted. 
     With combined reference to  FIGS. 1 through 4 , for instance, embodiments of the apparatus  10  of the present invention can be seen to be founded on an elongate body portion  12 . A handle portion  14  is fixed to a proximal end of the body portion  12 , and a distal tip portion  16  is fixed to the distal end of the body portion  12 . The body portion  12 , the handle portion  14 , and the distal tip portion  16  could be separately formed and fixed to one another, or two or more of the body portion  12 , the distal tip portion  16 , and the handle portion  14  could be integrally formed in certain practices of the invention. With the elongate body portion  12 , the apparatus  10  may alternatively be referred to as a long, thin, flexible medical device (LTFMD)  10 . As taught herein, the LTFMD  10  uniquely works in concert with the main or secondary lumen  102  or  104  of a nasogastric or orogastric tube  100 . 
     According to the invention, the LTFMD  10  can be contoured and configured to perform at least three different and useful tasks while inside the lumen  102  or  104  of an NG tube  100 . The first task is to assist the distal portion  106  of the NG tube  100  to traverse the terrain during insertion. The second task is to check the passageway of a lumen  102  or  104  for a blockage or compromise. The third task is to confirm whether the distal portion  106  of the NG tube  100  is inside the stomach as intended. A LTFMD  10  can be designed to perform each task individually or in any combination. 
     The body portion  12  and potentially the distal tip portion  16  of the LTFMD  10  can be cylindrical, hexagonal, octagonal, or any other shape that will allow the LTFMD  10  to properly perform one or more of the tasks above inside the lumen  102  or  104  of the NG tube  100  into which it is to be inserted. The components of the LTFMD  10  can be made completely or partially of materials commonly employed in the medical device field, such as, but not limited to metals, polymers, synthetic rubbers, combinations thereof. 
     Potential metals for the LTFMD  10  and particularly the body portion  12  and the distal portion  16  thereof could include, but again are not limited to, aluminum, solid steel or nitinol core wires, and solid core wire wrapped in a smaller wire coil or braid. Coiled or braided wires offer a large amount of flexibility, longitudinal pushing force, and kink resistance. Nitinol is highly elastic and offers good flexibility and torque in tortuous anatomy and pathways. These materials allow the apparatus  10  to have similar flexibility as that of a nasogastric tube  100  while traversing the terrain during insertion. Concomitantly, the body portion  12  of the LTFMD  10  adds rigidity and firmness sufficient to assist the tube  100  to maintain integrity and to not collapse during insertion. 
     Potential polymers for the LTFMD  10  and particularly the body portion  12  and the distal tip portion  16  thereof could include, but again are not limited to, natural and synthetic rubber, polyurethanes, silicone, and other polymeric materials. Embodiments of the LTFMD  10  are contemplated wherein solid or braided steel or nitinol wires are coated with a polymer such as, but not limited to, silicone or polytetrafluoroethylene (PTFE), to increase lubricity. Further, hydrophilic coatings may be applied to reduce friction during deployment and to ease movement in tortuous pathways. The body portion  12  and the distal tip portion  16  could have smooth or textured surfaces. In the depicted embodiments of  FIGS. 1 and 2 , for instance, the distal tip portions  16  are smooth while the body portions  12  have ribbed exterior surfaces. 
     The above metals and polymers give the LTFMD  10  the ability to be inserted and to traverse the passageway of the lumens  102  and  104  of an NG tube  100  smoothly and without resistance, fracturing, or breaking. 
     In practices of the invention and with particular reference to  FIGS. 1 and 2 , the LTFMD  10  may have a core  26  of metal or plastic. In one embodiment, for instance, the core  26  may be of nitinol. In embodiments of the LTFMD  10 , the nitinol core  26  may be surrounded by a laterally-ribbed sheath  28 , which could be of a polymer, such as but not limited to a polymer selected from synthetic rubber or polyurethane. 
     As set forth above, the handle  14  of the LTFMD  10  is fixed to the proximal end of the body portion  12 . A distal portion of the handle  14  is attached to the proximal end of the body portion  12  while the opposite, proximal portion of the handle  14  is free and not attached to anything. The proximal portion of the handle  14  is wider than the diameter of the proximal end of the body portion  12 . The proximal portion of the handle  14  is also crafted to be wider than the diameter of the entrance aperture  110  or  112  of the lumen  102  or  104  of the NG tube  100  into which the LTFMD  10  is to be inserted. The wider diameter of the proximal portion of the handle  14  eliminates the possibility of the body portion  12  and the distal tip portion  16  falling inside a lumen  102  or  104  and becoming irretrievable, trapped, or stuck inside. 
     In some embodiments, the handle  14  is configured so that a user is able to use a thumb and index finger to grip and control movement of the LTFMD  10  during insertion or removal from a lumen  102  or  104 . In some embodiments, the handle  14  is configured so that a user is able to use a thumb, index finger and middle finger to grip and control movement of the LTFMD  10  during insertion or removal from a lumen  102  or  10 . 
     The body portion  12  of the LTFMD  10  is uniquely contoured and configured to traverse the upper and middle passageways of the main or secondary lumens  102  or  104  of an NG tube  100  in which the LTFMD  10  is intended to be fully inserted. 
     The outer diameter of the body portion  12  of a LTFMD  10  may be dependent on the inner diameter of the lumen  102  or  104  of the NG tube  100  into which it is intended to be inserted and the intended task or purpose of the apparatus  10 . However, the outer diameter of the body portion  12  of the LTFMD  10  is preferably small enough to allow the body portion  12  to traverse the upper and middle passageway of the lumen  102  or  104  into which it is intended to be inserted, without significant resistance, when the upper and middle passageway of the lumen  102  or  104  is without a blockage, obstruction, or other compromise. 
     In certain embodiments, the outer diameter of the body portion  12  of the LTFMD can taper similarly to part or all of the upper and middle passageways of the main or secondary lumen  102  or  104  of the NG tube  100  into which it is to be inserted. 
     The distal tip portion  16  is attached to the distal end of the body portion  12  and is uniquely contoured and configured to traverse the upper, middle, and lower end passageways of the main or secondary lumens  102  or  104  of the NG tube  100  into which the apparatus  10  is intended to be fully inserted. 
     The outer diameter of the distal tip portion  16  of the LTFMD  10  may be dependent on the inner diameter of the upper, middle, and lower passageways of the lumen  102  or  104  of the NG tube  100  into which it is intended to be inserted and on the intended task or purpose of the apparatus  10 . However, the outer diameter of the distal tip portion  16  of the LTFMD  10  is preferably small enough to allow the tip portion  16  to traverse the proximal, middle, and distal passageways of the main or secondary lumens  102  or  104  of the NG tube  100  into which it is to be inserted, without significant resistance, when the upper, middle, and lower passageways of the lumen  102  or  104  is without a blockage, obstruction, or compromise. 
     The distal tip portion  16  of the LTFMD  10  is not sharp. It may be blunt, flat, rounded, or otherwise shaped. In  FIGS. 1, 11, and 13 , for instance, the distal tip portion  16  is an elongate, rounded oblong shape. In  FIGS. 2 and 12 , for example, the distal tip portion  16  is tapered to a rounded end. 
     The body portion  12  of the LTFMD  10  has a first length and the distal tip portion  16  of the LTFMD  10  has a second length. The first length is normally greater than the second length. The combined lengths of the body portion  12  and the distal tip portion  16  of the LTFMD  10  will typically not exceed the full length of the passageway of the lumen  102  or  104  of the NG tube  100  in which it is to be inserted. However, the combined length of the body portion  12  and distal tip portion  16  of the LTFMD  16  will ideally be long enough to extend entirely or substantially entirely the length of the passageway of the lumen  102  or  104  of the NG tube  100  in which it is to be inserted. The combined length of the body portion  12  and the distal tip portion  16  of a LTFMD  10  will ideally be sufficient to permit, when the apparatus  10  can be fully inserted in a lumen  102  or  104 , enough of the passageway of the lumen  102  or  104  will have been traveled and probed by the apparatus  10  to confirm that the lumen  102  or  104  does not have a blockage, obstruction or other compromise. 
     According to embodiments of the invention, the length of the LTFMD  10  will be sufficient to perform a plurality of tasks. More particularly, the LTFMD  10  has a length sufficient that, when the apparatus  10  is fully inserted in the passageway of a lumen  102  or  104  of an NG tube  100  as in  FIG. 10 , for instance, the presence of the distal tip portion  16  of the apparatus  10  inside the distal portion  106  of the NG tube  100  permits the distal tip portion  16  of the apparatus  10  and the distal portion  106  of the NG tube  100  to work in concert, mutually assisting in navigating the terrain during insertion. Moreover, the length of the LTFMD  10  is sufficient that, when the apparatus  10  is fully inserted in the passageway of a lumen  102  or  104  of an NG tube  100 , the apparatus  10  ensures that enough of the passageway of the lumen  102  or  104  has been traveled and probed to prove that the lumen  102  or  104  does not have a blockage, obstruction, or compromise. It will thus be understood that the actual length of the LTFMD  10  will then be determined based on the full length of the passageway of the lumen  102  or  104  of the NG tube  100  in which it will be inserted. 
     Still further, the LTFMD  10  has a length sufficient that, when the apparatus  10  is fully inserted in a lumen  102  or  104  of an NG tube  100  that is believed to be satisfactorily inserted in a person, the distal tip portion  16  of the apparatus  10 , when incorporating one or more pH indicator sensors as taught herein and further described hereinbelow, is able to confirm whether the distal portion  106  of the NG tube  100  is in fact located in the stomach of the person. 
     When a LTFMD  10  according to the invention is fully inserted in a lumen  102  or  104  of an NG tube  100  before or after the distal portion  106  of the tube  100  is inserted in the nose of a person and then satisfactorily advanced, the person is not hindered or harmed by the presence of the LTFMD  10 . 
     In one or more non-limiting embodiments where a purpose of the distal tip portion  16  of the LTFMD  10  is to assist the lower end of an NG tube  100  in traversing the terrain of the pathway from the nose to the stomach in a person during the insertion phase, the distal tip portion  16  of the LTFMD  10  is configured to be sufficient in diameter and rigidity such that the LTFMD  10 , when fully inserted into the NG tube  100 , adds firmness to the distal portion  106  of the NG tube  100  sufficient to prevent the distal portion  106  of the NG tube  100  from deviating or compromising when it encounters, for instance, friction or resistance points along the insertion path but not so much firmness and rigidity as to prevent the flexibility required of the NG tube  100  to permit insertion. 
     In practices of the invention, a purpose of the LTFMD  10  is to check the passageway of a lumen  102  or  104  of an NG tube  100  for a blockage, obstruction, or other compromise as exists, for example, in  FIG. 8 . The outer diameter of the body portion  12  and, additionally or alternatively, the distal tip portion  16  of the LTFMD  10  is configured to be sufficiently large that, when the inner diameter of the passageway of the lumen  102  or  104  in which it is to be inserted is reduced smaller than the outer diameter of the body and distal tip portions  12  and  16  of the LTFMD  10 , a user cannot insert the LTFMD  10  beyond the reduced inner diameter passageway of the lumen  102  or  104  without restriction by blockage, obstruction, or other compromise, assuming the LTFMD  10  is not already inserted in the lumen  102  or  104  prior to the reduction. Moreover, where a compromise comes to exist with the LTFMD  10  fully inserted into the NG tube  100  as in  FIG. 9 , the reduction in the inner diameter of the NG tube  100  tends to prevent retraction of the LTFMD  10  relative to the NG tube  100  thereby again providing a positive indication that an obstruction exists in the NG tube  100 . 
     Resistance during the insertion attempt is thus an affirmative indication to the user that the passageway of the lumen  102  or  104  into which the user is attempting to insert the apparatus  10  is either blocked, obstructed, or compromised. Based on this affirmative indication, the user will likely remove the NG tube  100  from inside the person and restart the insertion process. The LTFMD  10  with the sufficiently large diameter described above is capable of producing this positive indication immediately after an NG tube  100  has been believed to be satisfactorily inserted without a need for the use of x-rays. 
     In certain embodiments, as depicted in  FIG. 14 , the outer surface of the LTFMD  10 , such as the outer surface of the body portion  12 , has at least one longitudinal reinforcing rib or raised bar  30  attached thereto that increases the thickness and effective outer diameter of the apparatus  10  at the location of the rib or raised bar  30 . The increase in thickness of the outer diameter of the LTFMD  10  created by the presence of the rib or raised bar  30  increases the resistance of the apparatus  10  at the location of the rib or raised bar  30  when the apparatus  10  is being inserted in or removed from a lumen  102  or  104  of an NG tube  100  that has a blockage, obstruction or kink or twist type of compromise. 
     In non-limiting embodiments, as depicted in  FIG. 15 , the sheath  28  of the body portion  12  or the distal tip portion  16  of the LTFMD  10  has one or more notches  32  in the form of an indentation or incision in the body portion  12  or the distal tip portion  16 . The notch  32  demonstrates decreased resistance to flexion in comparison to segments of the long, thin, flexible structure formed by the body portion  12  or the distal tip portion  16  disposed adjacent to the notch  32 . The notch  32  thus causes the body portion  12  or the distal tip portion  16  to bend and form an angle between the two segments adjacent to the notch  32  rather than continuing the form of a curve when flexed in the vicinity of the notch  32 , such as when encountering a curve while traversing the passageway of a lumen  102  or  104  of an NG tube  100 . The angle formed by the bending between the segments to opposed sides of the notch  32  tends to cause the segments to opposite sides of a notch to straighten or remain straight and disposed in different directions. The straightened segments disposed along different directions make it difficult for the apparatus  10  to traverse the curviness of a lumen  102  or  104  that has formed a coil or loop type of compromise. Multiple notches  32  in the body portion  12  and, additionally or alternatively, the distal tip portion  16 , which notches  32  may be separated by equal distance or unequal distances, will make it even more difficult for the straightened segments or portions of the LTFMD  10  to traverse the passageway of a lumen  102  or  104  that has formed a coil or loop type of compromise. 
     The LTFMD  10  can additionally include one or more measurement markings, scale, or demarcations  34  on the body portion  12  and the distal tip portion  16  of the apparatus  10  as is illustrated in  FIG. 14 . With that, the user can readily identify the full length of the LTFMD  10  minus the handle portion  14 . By way of non-limiting example, embodiments of the LTFMD  10  have a numbering scale comprising measurement markings  34  arranged on the body portion  12  and the distal tip portion  16  wherein a highest number is disposed adjacent to the proximal end of the body portion  12  with progressively decreasing numbers toward and over the distal tip portion  16 . Under such constructions, where a user is unable to insert the distal tip portion  16  and the body portion  12  into the lumen  102  or  104  of the NG tube  100  fully after the NG tube  100  is believed to be satisfactorily and fully inserted into a person as in  FIG. 8 , for example, the numbering scale  34  indicates how deep the blockage, obstruction, or compromise of the tube  100  is inside the person. For instance, the blockage, obstruction, or compromise can be indicated to be equal to the first visible number seen on the LTFMD  10  adjacent to the proximal entrance opening  110  or  112  of the lumen  102  or  104 . 
     With a recognition that nasogastric and orogastric tubes come in various lengths, typically ranging from 6 inches to 6 feet, it is further contemplated as in  FIG. 20  that a single long, thin, flexible medical structure may, for reasons of economy or otherwise, have a length that subsumes the range of the lengths of typical gastric tubes and their lumens. There, the long, thin, flexible medical device  10  has measurement indicators  34 , in this case numbering but alternatively color coding or any other marking indicators, that denote various lengths indicating a depth of insertion corresponding to known lengths of different gastric tube lumens. In this non-limiting example, the LTFMD  10  has a marker indicative of a 12-inch lumen length and further markers indicative of 24-inch and other predetermined lumen lengths. With this, an ability to insert the LTFMD  10  up to the 12-inch lumen length marking indicator  34  in a gastric tube known to have a 12-inch lumen length will provide a positive indication that the tube is not blocked or otherwise compromised. A manufacturer could thus produce a long, thin, flexible medical device  10  in a single length designed to fit most or even all possible lengths of nasogastric and orogastric tubes. In use, a practitioner would merely be required to identify the marking indicator  34  on the LTFMD  10  corresponding to the selected gastric tube lumen length and determine whether that length of the LTFMD  10  can be inserted into and removed from the gastric tube without obstruction while the gastric tube is in place within the patient. 
     As shown, for instance, in  FIGS. 1-6, 11, and 13 , the LTFMD  10  can further incorporate one or more pH sensors to form a pH sensor array  15  to facilitate the rapid detection of whether an NG tube  100  in which the apparatus  10  is inserted has indeed been successfully placed in the stomach. As used herein, the term “pH” has the meaning normally associated with it in the field of chemistry: the “power of hydrogen,” which is a measurement of the hydrogen ion concentration. A pH level is indicative of the degree of acidity or alkalinity in a fluid. The pH scale ranges from 1 to 14. A pH of 7 is considered to be neutral, a pH of 1 is totally acidic, and a pH of 14 is completely alkaline. 
     pH indicators are known wherein a halochromic chemical compound is added in small amounts to solutions so that the pH of the solution can be determined visually. A pH indicator detects the presence of H+ and OH−. It does this by reacting with H+ and OH−, which are themselves weak acids and bases. If an indicator is a weak acid and its conjugate base has a different color, deprotonation causes a color change. 
     It is further known that the human body comprises different bodily fluids, each with a characteristic and a different pH value. A pH indicator soaked and dried on a color or non-color filter paper will turn a verifiable color when it comes in contact with a fluid being tested. For example, Table 1 provides a small representative, but non-limiting, list of common pH indicators used in medicine. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Common pH Indicators 
               
            
           
           
               
               
               
               
            
               
                   
                 Indicator 
                 Acid Color 
                 Base Color 
               
               
                   
                   
               
               
                   
                 Bromothymol Blue 
                 Yellow 
                 Blue 
               
               
                   
                 Phenol red 
                 Yellow 
                 Red 
               
               
                   
                 Phenolphthalein 
                 Colorless 
                 Magenta 
               
               
                   
                   
               
            
           
         
       
     
     Gastric acid, gastric juice, or stomach acid is a digestive fluid formed only in the stomach and is composed of hydrochloric acid, potassium chloride, and sodium chloride. Since acid-base pH indicators are solutions that have a characteristic color at certain pH levels, they can be used to visually signal the acidity of an aqueous (water-based) solution, such as gastric acid. 
     Alkaline mucus is a thick fluid produced by mammals. It confers tissue protection in an acidic environment, such as in the stomach. Alkaline mucus has a characteristic color at certain pH levels and can be used to visually signal the alkalinity of an aqueous (water-based) solution in the stomach. 
     Filter paper material is a semi-permeable paper barrier that is typically placed perpendicular to a liquid or air flow. All filter paper materials have various properties. Important parameters include wet strength, porosity, particle retention, volumetric flow rate, efficiency, and capacity. There are two mechanisms of filtration with paper: volume and surface. By volume filtration, the particles are caught in the bulk of the filter paper. By surface filtration, the particles are caught on the paper surface. Filter paper materials may therefore be considered advantageous since even a small piece of filter paper will absorb a significant volume of liquid, such as gastric acid. 
     Porous materials, such as gauze, are a thin, translucent fabric of silk, linen, cotton, or a very fine wire mesh. Porous materials also have two mechanisms of filtration and can be used like filter paper materials because even a small piece of gauze will absorb a significant volume of liquid, such as gastric acid. 
     According to embodiments of the invention, the distal portion of the LTFMD  10 , such as the distal tip portion  16  thereof, can include a pH sensor array  15  comprising one or more swabs or sensors  18 ,  20 ,  22 , and  24 . In the embodiment of  FIG. 1 , for instance, the pH sensor array  15  includes three swabs or sensors  18 ,  20 , and  22 . In the embodiments of  FIGS. 3 and 4 , for example, the pH sensor array  15  includes four swabs or sensors  18 ,  20 ,  22 , and  24 . Each swab or sensor  18 ,  20 ,  22 , and  24  can incorporate a pH indicator. For avoidance of doubt, a pH sensor array  15  could include just a single swab or sensor  18 . The pH indicators of the sensors  18 ,  20 ,  22 , and  24  can be the same or different, calibrated to check for the same liquid or different liquids. Each swab or sensor  18 ,  20 ,  22 , and  24  can be composed completely or partially of filter paper, gauze, or any porous or other material capable of retaining a pH indicator, such as by being soaked therein. Swabs or sensors  18 ,  20 ,  22 , and  24  can be retained in any manner, such as by being attached to the distal tip portion  16  of the LTFMD  10  by glue, adhesive paper, spray adhesive, or any known method capable of bonding the two together. 
     When a LTFMD  10  with a pH sensor array  15  incorporated into the distal tip portion  16  is fully inserted in the main lumen  102  of an NG tube  100  as, for instance, in  FIGS. 4  and  6 , the pH sensor array  15  can be disposed to be aligned with the eyelet openings  108  in the distal portion  106  of the main lumen  102 . The alignment of the pH indicator sensors  18 ,  20 ,  22 , and  24  of the pH sensor array  15  in the distal portion  106  of the LTFMD  10  with the eyelet openings  108  in the distal portion  106  of the main lumen  102  ensures a user that fluid surrounding the main lumen  102  that passes through an eyelet opening  108  will make contact with a pH indicator sensor  18 ,  20 ,  22 , and  24  of the pH sensor array  15 . The result of the contact between the fluid and the pH indicator sensors  18 ,  20 ,  22 , and  24  of the pH sensor array  15  produces a verifiable color change confirming either that the fluid that made contact with the pH indicator sensor is the fluid being searched for by the pH indicator or, where there is no change in color, that the fluid being searched for by the pH indicator has not been contacted. 
     When a LTFMD  10  with a pH sensor array  15  incorporated in the distal tip portion  16  is fully inserted in the secondary lumen  104  of an NG tube  100  as in  FIGS. 3 and 5 , for example, the pH sensor array  15  will be aligned or disposed as closely as possible relative to an opening  114  in the distal portion  106  of the NG tube  100  between the main lumen  102  and the secondary lumen  104 . The alignment of the pH sensor array  15  at the distal portion  106  of the LTFMD  10  with the opening  114  at the distal end of the secondary lumen  104  ensures a user that fluid surrounding the distal portion  106  of the LTFMD  10  that passes through the eyelet openings  108  will pass through the opening  114  to make contact with the pH indicator sensors  18 ,  20 ,  22 , and  24  of the pH sensor array  15 . The result of the contact between the surrounding fluid and the pH indicator sensors  18 ,  20 ,  22 , and  24  will either produce a verifiable color change or no change in color, again positively confirming whether the fluid that made contact with the pH indicator sensors  18 ,  20 ,  22 , and  24  is the liquid being searched for by the pH indicator. 
     Accordingly, a LTFMD  10  incorporating a pH sensor array  15  can be used to test for, without limiting the applicability of the invention except as the claims expressly require, the presence of gastric acid, alkaline, and other fluids found in the digestive system or lungs of a person. 
     In certain embodiments where a purpose of the LTFMD  10  is to confirm the placement of the distal portion  106  of the main lumen  102  of the NG tube  100  inside a person as in  FIG. 4 , for example, the distal tip portion  16  of the LTFMD  10  retains one or more pH acidic base indicator sensors  18 ,  20 ,  22 , and  24 . The diametrical size and configuration of the body portion  12  and the distal tip portion  16  of the apparatus  10  can be much smaller than the diametrical size of the body portion  12  and distal tip portion  16  that would be used in this same main lumen  102  if the purpose of the apparatus  10  were to assist during insertion or in checking for a blockage, obstruction, or compromise. The smaller diametrical size of the body portion  12  and distal tip portion  16  of the LTFMD  10  will give the LTFMD  10  the ability to be inserted and removed by the user quickly and without significant interference or resistance since the only concern is to have the distal tip portion  16  of the apparatus  10  make contact with the fluid that enters the distal portion  106  of the NG tube  100 . 
     Embodiments of the invention can, for instance, have plural pH indicator sensors  18 ,  20 , and  22  retained by the distal tip portion  16  as in  FIG. 11 . As in the depicted embodiment, the sensors  18 ,  20 , and  22  of the array  15  of pH indicator sensors can be spaced in longitudinal alignment along the distal tip portion  16 . At least two of the pH indicator sensors  18 ,  20 , and  22  can incorporate different types of pH indicators. The pH sensors  18 ,  20 , and  22  can be located in different areas on the distal tip portion  16  or elsewhere on the LTFMD  10 . For instance, a first pH sensor  18  could be located on the upper half of the distal tip portion  16  and can retain a pH alkaline base indicator, a third pH indicator sensor  22  can be located on the lower half of the distal tip portion  16  and can retain a pH acidic base indicator, and a second pH indicator sensor  20  can be disposed between the first and third sensors  18  and  22  and can retain a pH alkaline base indicator, a pH acidic base indicator, or some other test indicator. Such multi-pH indicator sensor embodiments allow a user to test for the presence of two different body fluids simultaneously thereby saving time, money, and discomfort to a person. 
     In certain practices, the LTFMD  10  can be employed when an NG tube  100  without a LTFMD  10  inside a lumen  102  or  104  is inserted in a person and then an x-ray is taken to locate the distal portion  106  of the NG tube  100  showing that the distal portion  106  of the NG tube  100  is much farther down inside the stomach than desired and needs to be pulled back several centimeters. After the NG tube  100  has been pulled back several centimeters, the user may not wish to radiate the person again by x-rays just to check the retracted location of the distal portion  106  of the NG tube  100 , but the user is interested in confirming that the distal portion  106  of the NG tube  100  is still inside the stomach. The user may then choose to insert a LTFMD  10  configured with a body portion  12  and distal tip portion  16  of equal outer diameters both much smaller than the diametrical size that would be used to check for a compromise in the lumen  102  or  104  into which it is to be inserted. The smaller outer diameter of the LTFMD  10  will allow the body and distal tip portions  12  and  16  to traverse the lumen  102  or  104  faster and without interference. The LTFMD  10  can incorporate one or more pH acidic base indicator sensors  18 ,  20 ,  22 , and  24  in the distal tip portion  16 . 
     With such an LTFMD  10  provided, the user can fully insert the LTFMD  10  with the pH acidic base indicator sensor or sensors  18 ,  20 ,  22 , and  24  retained by the distal tip portion  16  into the main lumen  102  of the NG tube  100 . Fluid that enters the eyelet openings  108  in the distal portion  106  of the main lumen  102  from the surrounding area outside the NG tube  100  will then make contact with the pH acidic base indicator sensors  18 ,  20 ,  22 , and  24  at the distal tip portion  16  while disposed in the distal portion  106  of the main lumen  102  and, ideally, aligned with the eyelet openings  108  as shown, for instance, in  FIG. 4 . A verifiable color change, or conversely no change in color, of the pH acidic base indicator sensor or sensors  18 ,  20 ,  22 , and  24  will positively indicate whether the lower end of the main lumen  102  of the NG tube  100  is still inside the stomach after being retracted several centimeters. This confirmation can be made in seconds, and the delay, cost, inconvenience, and excess radiation deriving from further x-ray procedures are avoided. 
     Also according to embodiments of the invention, after a user has fully inserted an NG tube  100  without a LTFMD  10  inside a lumen  102  or  104  into a person and then the person develops a persistent cough, the user may become concerned regarding whether the NG tube  100  has veered off course and landed inside a lung of the person instead of the stomach. There are two ways the user can check the location of the NG tube  100  inside the person using the LTFMD  10  instead of using x-rays. 
     One way is for the user to choose a LTFMD  10  that is incorporated with one or more pH acidic base indicator sensors  18 ,  20 ,  22 , and  24  at the distal tip portion  16 . The diameters of the body portion  12  and the distal tip portion  16  of the LTFMD  10  are small enough to traverse the passageway of the main lumen  102  of the NG tube  100  in which it will be inserted. With such an LTFMD  10  provided, the user fully inserts the LTFMD  100  with the pH acidic base indicator sensor or sensors  18 ,  20 ,  22 , and  24  then disposed in the distal portion  106  of the NG tube  100 . The fluid that enters the eyelet openings  108  in the distal portion  106  of the main lumen  102  from the surrounding area outside the NG tube  100  makes contact with the pH acidic base indicator sensor or sensors  18 ,  20 ,  22 , and  24  retained by the distal tip portion  16  of the LTFMD  10 . The user can then turn the handle  14  of the LTFMD  10  clockwise and counter-clockwise and retract and advance the apparatus  10  several times to help fluid inside the distal portion  106  of the NG tube  100  make contact with the pH indicator sensor or sensors  18 ,  20 ,  22 , and  24  of the apparatus  10 . The user can then completely remove the LTFMD  10  from the main lumen  102  of the NG tube  100  and visually review the pH indicator sensor or sensors  18 ,  20 ,  22 , and  24  at the distal tip portion  16 . A verifiable color change or a lack of a color change of the pH acidic base indicator sensor or sensors  18 ,  20 ,  22 , and  24  of the color being searched for will positively indicate whether the distal portion  106  of the main lumen  102  of the NG tube  100  is inside the stomach with, for instance, a verifiable color change indicating that the distal portion  106  is inside the stomach and a lack of a color change indicating that the distal portion  106  is not inside the stomach. 
     The second way the user can use the LTFMD  10  to confirm whether the NG tube  10  is in a lung or the stomach is for the user to choose a LTFMD  10  incorporated with a pH sensor array  15  with a pH indicator sensor or sensors  18 ,  20 ,  22 , and  24  sensitive to the composition of lung fluid. In certain practices, the sensor array  15  can include one or more pH indicator sensors  18 ,  20 ,  22 , and  24  sensitive to the composition of lung fluid and one or more pH indicator sensors  18 ,  20 ,  22 , and  24  sensitive to gastric acid. In any event, the diameter of the body portion  12  and the distal tip portion  16  of the LTFMD  10  will be sufficiently small to traverse the passageway of the main lumen  102  of the NG tube  100  in which it will be inserted. The user fully inserts the LTFMD  10  with the pH indicator sensor or sensors  18 ,  20   22 , and  24  sensitive to the composition of lung fluid to dispose the pH sensor array  15  in the distal portion  106  of the main lumen  102  of the NG tube  100 . The fluid that enters the eyelet openings  108  in the distal portion  106  of the main lumen  102  of the NG tube  100  from the area surrounding the NG tube  100  makes contact with the pH indicator sensor or sensors  18 ,  20 ,  22 , and  24  sensitive to the composition of lung fluid incorporated on the distal tip portion  16  of the LTFMD  10 . The user can then turn the handle portion  14  of the LTFMD  10  clockwise and counter-clockwise and extend and retract the apparatus  10  several times to help fluid inside the distal portion  106  of the NG tube  100  to make contact with the pH indicator sensor or sensors  18 ,  20 ,  22 , and  24 . The user can then completely remove the LTFMD  10  from the lumen  102  or  104  of the NG tube  100  and visually review the pH indicator sensor or sensors  18 ,  20 ,  22 , and  24  of the distal tip portion  16 . A verifiable color change of the pH indicator sensor or sensors  18 ,  20 ,  22 , and  24  sensitive to the composition of lung fluid of the color being searched for will confirm whether the distal portion  106  of the main lumen  102  of the NG tube  100  is inside a lung with, for instance, a verifiable color change indicating that the distal portion  106  is inside a lung and a lack of a color change indicating that the distal portion  106  is not inside a lung. 
     Where applicable, a verifiable color change of the pH indicator sensor or sensors  18 ,  20 ,  22 , and  24  sensitive to the gastric acid will confirm whether the distal portion  106  of the main lumen  102  of the NG tube  100  is inside the stomach. Both of the above methods using the LTFMD  10  will result in a positive confirmation for the user and can be performed in seconds after an NG tube  100  is inserted without a delay and without radiating the person with an x-ray. 
     The same diameter LTFMD  10  and steps described above can be used when a user inserts an NG tube  100  without a LTFMD  10  inside a lumen  102  or  104  into a person and the person develops a persistent cough after the insertion. In such an instance, the user may become concerned regarding whether the NG tube  100  veered off course and is now in a lung. The user can quickly insert a LTFMD  10  into the lumen  102  or  104  of the NG tube  100  to obtain a positive indication of the location of the distal portion  106  of the NG tube  100  based on the color change or lack of color change of the pH indicator sensor or sensors  18 ,  20 ,  22 , and  24  of the pH sensor array  15 . 
     In one or more non-limiting embodiments, a two-prong approach using the LTFMD  10  may be practiced by a user. There are times in medicine when, after the insertion of a two-lumen NG tube  10  is confirmed by an x-ray, the main or suction lumen  102  of the NG tube  100  is then connected to a suction device (not shown). Sometime later, suctioning through the NG tube  100  appears to a user to be sluggish and erratic. In this situation, the main or suction lumen  102  of the NG tube  100  can remain connected to the suction device while the user selects a first LTFMD  10 , such as the LTFMD  10  depicted in  FIG. 12 , configured with a sufficiently large diameter to be capable of checking the secondary lumen  104  of the tube  100  for a compromise. The user seeks to determine if the tube  100  has become blocked, obstructed, or compromised and is the reason for the erratic suctioning behavior. The user inserts the distal tip portion  16  of a first LTFMD  10  into the secondary lumen  104  of the NG tube  100  and advances the apparatus  100  in the lumen  104 . If the user is able to insert the full length of the first LTFMD  10  inside the secondary lumen  104  without resistance from a blockage, obstruction, or other compromise, this is a positive sign to the user that the secondary lumen  104  does not have a blockage, obstruction, or other compromise, and whether the main lumen  102  of the NG tube  100  has a compromise or another reason for the erratic suctioning behavior must be considered. 
     Being successful in fully inserting the first LTFMD  10  into the secondary lumen  104 , the user may next decide to disconnect the main lumen  102  of the NG tube  100  from the suction device in an effort to see if the main lumen  102  is partially blocked or obstructed by a solid object such as a clot or food particle that can be the cause for the erratic suctioning behavior. This time, the user may select a second LTFMD  10 , such as that depicted in  FIG. 2  or  13 , configured with a much larger diameter than the diameter of the first LTFMD  10  but still small enough to traverse the main lumen  102  of the NG tube  100  with resistance or interference when the lumen  102  is without a blockage or obstruction. The larger diameter corresponds to the larger diameter of the main lumen  102  as compared to the secondary lumen  104 . The body portion  12  and the distal tip portion  16  of the second LTFMD  10  both have the larger diameter. The second LTFMD  10  may or may not have a pH sensor array  15 . The user inserts the second LTFMD  10  with the much larger diameter into the main lumen  102  of the NG tube  100  to check if the main lumen  102  is partially blocked or obstructed by a solid object. If the entire length of the second LTFMD  10  is able to be fully inserted in the main lumen  102  of the NG tube  100  by the user without resistance from a blockage, obstruction, or other compromise, this is a positive indication that the erratic suctioning behavior is not due to a blockage or obstruction inside the main lumen  102  of the tube  100 . The user must consider another reason for the erratic suctioning behavior. 
     Apparatuses  10  according to the present invention may be packaged in multiple different ways. For instance, apparatuses  10  may be packaged as individual units and may be specified for the main lumen  102  or the secondary lumen  104  of NG tubes  100  of specific dimensions. In other practices, LTFMDs  10  as disclosed herein may be packaged in bulk. Still further, the LTFMD  10  may be packaged as a kit and system that includes at least one LTFMD  10  according to the present invention and at least one NG tube  100 . The at least one LTFMD  10  and the at least one NG tube  100  may be sized in correspondence, such as for the LTFMD  10  to be received into the main lumen  102  of the NG tube  100 , for the LTFMD  10  to be received into the secondary lumen  104  of the NG tube  100 , or with first and second LTFMDs  10  sized to be received into the main and secondary lumens  102  and  104  respectively. Such kits or systems may be packaged in sterile disposable or recyclable packaging. 
     The LTFMD  10  so shown and described has utility in assisting in, checking, and confirming the placement of a distal portion of a lumen  102 ,  104  of a gastric tube  100  in a stomach of a patient. Nonetheless, the present inventor has recognized that confirming the proper placement of the distal portion  106  of an NG tube  100  through radiography may nonetheless be additionally or alternatively desirable. In this regard, the difficulty or inability of x-ray imaging to visualize the exact location and positioning of the tip or openings within the distal portion of a standard gastric tube  100  is again noted. Such limitations of the prior art contribute significantly to the risk of misinterpretation of tube placement during x-ray imaging. The inability to identify on a chest x-ray the exact location of the tip of a nasogastric tube and the eyelet opening or openings therein due to the radiotransmissive nature of the materials involved and the often confusing presence of other components, including leads and other wires, make x-ray interpretation difficult and prone to error. Serious complications, including death, can derive from the limitations and resulting errors in interpreting x-ray imaging. 
     In view of the limitations of x-ray imaging to confirm NG tube placement according to the prior art, the present inventor has devised of methods and apparatuses that facilitate x-ray visualization to check and confirm the placement of nasogastric and orogastric tubes  100  within a patient and, potentially, the location of the opening or openings in the gastric tube  100  with respect to the patient. One embodiment of the apparatus is indicated at  10  in  FIG. 16 . There, the LTFMD  10  again has an elongate body portion  12  that retains a distal tip portion  16 . Together, the elongate body portion  12  and the distal tip portion  16  form a long, thin, flexible structure for being matingly received into a lumen  102  of a gastric tube  100 . The long, thin, flexible structure is fully received into the lumen  102  of the gastric tube  100  such that the distal tip portion  16  of the LTFMD  10  is disposed within the distal portion  106  of the gastric tube  100 . 
     The passageway of the lumen  102  of the gastric tube  100  can be considered to have a length. That length can, for instance, extend from the entrance to the lumen  102  to the most distal end of the passageway, which in this embodiment is coincident with the most distal end of the gastric tube  100  but for the thickness of the end wall. Where the length of the long, thin, flexible structure formed by the body portion  12  and the distal tip portion  16  is at least approximately equal to the length of the passageway of the lumen  102 , the long, thin, flexible structure can be fully received into the lumen  102  of the gastric tube  100  in a substantially concentric relationship to cause the most distal tip of the distal tip portion  16  of the LTFMD  10  to be coincident or substantially coincident with the most distal end of the passageway of the lumen  102  of the gastric tube  100 . 
     In this configuration, the location and orientation of the distal tip portion  16  of the LTFMD  10  thus corresponds to, and is indicative of, the location and orientation of the distal portion  106  of the gastric tube  100 . The inventor has thus perceived that an ability to visualize the location and, ideally, the orientation of the distal tip portion  16  of the LTFMD  10  will concomitantly provide an indication of the location and, potentially, the orientation of the distal portion  106  of the gastric tube  100 . With this, the risks and dangers of misinterpretation and error with respect to gastric tube placement can be eliminated. 
     To facilitate an x-ray visualization of the location and orientation of the distal tip portion  16  of the LTFMD  10  within a patient and a concomitant, accurate determination of the location and orientation of the distal portion  106  of the gastric tube  100  in which it is received, embodiments of the LTFMD  10  incorporate an array of radiographic markers of radiopaque material, such as lead or any other radiopaque material, on, within, or otherwise retained by the distal tip portion  16  of the LTFMD  10  as is first shown in the non-limiting example of  FIG. 16 . There, the LTFMD  10  retains a first radiopaque marker  36 , which may be referred to as a tip marker  36 , substantially coincident with or comprising the most distal tip of the distal tip portion  16 . A second radiopaque marker  38  is retained by the distal tip portion  16  proximally spaced from the most distal tip of the distal tip portion  16  and, thus, from the first radiopaque marker  36  by a distance D 1 . A third radiopaque marker  40  is retained by the distal tip portion  16  proximally spaced from the second radiopaque marker  38  by a distance D 2  and thus from the first radiopaque marker  36  by the combined distances D 1  and D 2  Finally, a fourth radiopaque marker  42  is retained by the distal tip portion  16  proximally spaced from the third radiopaque marker  40  by a distance D 3  and thus from the first radiopaque marker  36  by the combined distances D 2 , D 2 , and D 3 . 
     Some or all of the first, second, third, and fourth radiopaque markers  36 ,  38 ,  40 , and  42  are unique with respect to one another. Here, for instance, where the distal tip portion  16  is round with a given diameter, the first radiopaque marker  36  can substantially match the distal tip portion  16  in shape and lateral dimension, such as with an annular cross section and diameter, and can terminate distally with a rounded end. The second radiopaque marker  38  has a shape and size that distinguish from the first radiopaque marker  36 , the second marker  38  here comprising a single annular portion of broadened diameter relative to the distal tip portion  16 . The third radiopaque marker  40  has a shape and size that distinguish from the first and second radiopaque markers  36  and  38 , the third marker  40  here comprising first and second longitudinally spaced annular portions of broadened diameter relative to the distal tip portion  16 . The fourth radiopaque marker  42  has a shape and size that distinguish from the first, second, and third radiopaque markers  36 ,  38 , and  40 , the fourth marker  42  here comprising first, second, and third longitudinally spaced annular portions of broadened diameter relative to the distal tip portion  16 . 
     Thus, the radiopaque markers  36 ,  38 ,  40 , and  42  not only distinguish from one another but also are effectively coded to indicate their longitudinal position on the distal tip portion  16 . The rounded end shape of the first radiopaque marker is, in this embodiment, indicative of its longitudinal position coincident with the most distal tip of the distal tip portion  16 . The single broadened portion of the second radiopaque marker  38  is indicative of its being the first marker spaced in longitudinal position from the most distal tip of the distal tip portion  16 . The two broadened portions of the third radiopaque marker  40  are indicative of its being the second marker spaced in longitudinal position from the most distal tip of the distal tip portion  16 . Likewise, the three broadened portions of the fourth radiopaque marker  42  are indicative of its being the third marker spaced in longitudinal position from the most distal tip of the distal tip portion  16 . 
     By virtue of the coding of the radiopaque markers  36 ,  38 ,  40 , and  42 , a practitioner aware of the dimensions D 1 , D 2 , and D 3  visualizing one marker  36 ,  38 ,  40 , or  42  can calculate and determine the relative location of the remaining markers  36 ,  38 ,  40 , and  42 . In a like manner, a practitioner visualizing two markers  36 ,  38 ,  40 , or  42  can calculate and determine the location and orientation of all markers  36 ,  38 ,  40 , and  42  and thus the location and orientation of the distal tip portion  16  of the LTFMD  10  in general. More importantly, where it is known that the distal tip portion  16  of the LTFMD  10  is disposed within the distal portion  106  of the gastric tube  100 , knowledge of the location and orientation of the distal tip portion  16  of the LTFMD  10  will necessarily provide knowledge of the matching location and orientation of the distal portion  106  of the gastric tube  100 . With that, the positioning of the distal portion  106  of the gastric tube  100  can be unmistakably verified. 
     As  FIG. 16  also illustrates, the locations of the markers  36 ,  38 ,  40 , and  42  on the distal tip portion  16  of the LTFMD  10  can correspond to the locations of noteworthy sites of the distal portion  106  of the gastric tube  100 . Here, for instance, the location of the first radiopaque marker  36  at the most distal tip of the distal tip portion  16  will correspond to the location of the distal end of the passageway of the lumen  102 . The second radiopaque marker  38 , which is spaced from the most distal tip of the distal tip portion  16  by the distance D 1 , corresponds in longitudinal position to that of the first eyelet or opening  108 A in the lumen  102  of the distal portion  106  of the gastric tube  100  that is likewise spaced from the end of the passageway by the distance D 1 . The third radiopaque marker  40 , which is spaced from the most distal tip of the distal tip portion  16  by the combined distances D 1  and D 2 , corresponds in longitudinal position to that of the second eyelet or opening  108 B in the lumen  102  of the distal portion  106  of the gastric tube  100  that is likewise spaced from the end of the passageway by the combined distances D 1  and D 2 . Lastly, the fourth radiopaque marker  42 , which is spaced from the most distal tip of the distal tip portion  16  by the combined distances D 1 , D 2 , and D 3 , corresponds in longitudinal position to that of the third eyelet or opening  108 C in the lumen  102  of the distal portion  106  of the gastric tube  100  that is likewise spaced from the end of the passageway by the combined distances D 1 , D 2 , and D 3 . Accordingly, knowledge of the location and coding of the radiopaque markers  36 ,  38 ,  40 , and  42  provides knowledge of the matching location of the first, second, and third eyelet openings  108 A,  108 B, and  108 C in the lumen  102  of the gastric tube  100 . 
     Other radiopaque marker configurations and codings are possible and within the scope of the invention. For instance, as is shown in  FIG. 17 , it would be possible for the first radiopaque marker  36 , which is disposed to form the most distal tip of the distal tip portion  16 , to comprise a broadened block of radiopaque material. The block could be rectangular, rounded, or otherwise shaped. The second radiopaque marker  38  in this embodiment has a shape and size that distinguish from the first radiopaque marker  36 , here comprising a single broadened ring of radiopaque material. The third radiopaque marker  40  has a shape and size that distinguish from the first and second radiopaque markers  36  and  38 , here comprising first and second longitudinally spaced, broadened rings of radiopaque material. The fourth radiopaque marker  42  has a shape and size that distinguish from the first, second, and third radiopaque markers  36 ,  38 , and  40 , here comprising first, second, and third longitudinally spaced, broadened rings of radiopaque material. The radiopaque markers  36 ,  38 ,  40 , and  42  are again spaced by the distance dimensions D 1 , D 2 , and D 3 , which correspond to the known spacing of the eyelet openings  108 A,  108 B, and  108 C in the distal portion  106  of the gastric tube  100 . 
     In the embodiment of  FIG. 17 , the gastric tube  100  has first and second sets of eyelet openings with the first, second, and third openings  108 A,  108 B, and  108 C of the first set in longitudinal alignment and with the first, second, and third openings  108 A 2 ,  108 B 2 , and  108 C 2  disposed in longitudinal alignment angularly spaced from the first set of openings  108 A,  108 B, and  108 C. The first and second sets of openings  108 A,  108 B, and  108 C and  108 A 2 ,  108 B 2 , and  108 C 2  are equally spaced such that a radiographic determination of the location of the first set of openings  108 A,  108 B, and  108 C based on the x-ray visualized locations of the first, second, third, and fourth radiopaque markers  36 ,  38 ,  40 , and  42  will likewise be indicative of the locations of the second set of openings  108 A 2 ,  108 B 2 , and  108 C 2 . 
     Referencing the different eyelet configurations of  FIGS. 16 and 17 , for example, it is noted that numerous eyelet opening configurations have been employed in prior art gastric tubes. Indeed, gastric tubes have been disclosed wherein eyelet openings are staggered around the length and, additionally or alternatively, the circumference of the tube. As a non-limiting example of the many possible configurations, a first eyelet opening of a first series of openings to one side of the tube may be at a first distance from the tip of the tube while a first eyelet opening of a second series of openings to a second side of the tube may be at a different distance from the tip of the tube. While embodiments of the LTFMD  10  may have arrays of radiopaque markers designed to correspond in position to each and every such eyelet opening, it is also readily possible and within the scope of the invention for the radiopaque markers to mark just a single opening location or the location of selected, known openings while the location of other openings may, for instance, be determined by their known position relative to the opening position marked with the radiopaque marker or markers. 
     Again, other radiopaque marker configurations and codings are possible and within the scope of the invention. As is shown in  FIG. 18 , for example, rather than being coded by numbers of broadened portions or protuberances, it would be possible for the radiopaque markers  36 ,  38 ,  40 , and  42  to be differently patterned to enable an identification and differentiation between the markers  36 ,  38 ,  40 , and  42 . As in the illustrative but not limiting embodiment of  FIG. 18 , for example, the first radiopaque marker  36 , which is retained at or forms the most distal tip of the distal tip portion  16 , comprises a solid member of radiopaque material substantially matching the body of the distal tip portion  16  in diameter and distally terminating in a rounded end. The second radiopaque marker  38 , however, has a pattern of radiographic material that is of a zig-zag or helical shape while the third radiopaque marker  40  has a pattern formed by an array of longitudinal strands of radiopaque material and the fourth radiopaque marker  42  has a pattern formed by an array of lateral strands of radiopaque material. With the radiopaque markers  42  having different patterns of radiopaque material, a practitioner aware of the patterns can readily identify each marker  36 ,  38 ,  40 , and  42  and differentiate between markers  36 ,  38 ,  40 , and  42 . With that, the location and orientation of the distal tip portion  16  of the LTFMD  10  and the distal portion  106  of the gastric tube  100  in which it is received can be determined with certainty. Moreover, with the location of the second, third, and fourth markers  38 ,  40 , and  42  known to correspond in distance from the most distal tip of the distal tip portion  16  to the distance of first, second, and third eyelet openings  108 A,  108 B, and  108 C from the most distal end of the passageway in the lumen  102  of the gastric tube  100 , the exact locations of the eyelet openings  108 A,  108 B, and  108 C can be precisely identified and confirmed. 
     Again, except as the claims may be expressly limited, it is possible within the scope of the invention for fewer radiographic markers to be incorporated, potentially with the radiopaque marker or markers again corresponding in longitudinal location along the distal tip portion  16  to the longitudinal location of the opening or openings in the gastric tube  100 . One such embodiment is depicted in  FIG. 19 . There, the LTFMD  10  is constructed with a radiographic marker  36  of radiopaque material, such as but not limited to lead, designed to correspond in longitudinal, and in this case lateral, position to the known longitudinal and lateral position of an opening  108  in the gastric tube  100  permitting a fluidic connection between the interior of the gastric tube  100  and its surroundings. The radiopaque marker  36  comprises a distinctly shaped torroidal member that is concentrically fixed to or comprises the most distal end of the distal tip portion  16 , and the gastric tube  100  has a concentric opening  108  in the most distal end thereof. Under this construction, the identification of the location and orientation of the torroidal radiopaque marker  36  will provide the practitioner with an identification of the location and orientation of the most distal tip of the distal portion  106  of the gastric tube  100  and, inferentially, the position and orientation of the remainder of the tip portion  106  of the gastric tube  100 . 
       FIGS. 20 through 22  show further embodiments of the LTFMD  10  wherein first, second, third, and fourth radiopaque markers  36 ,  38 ,  40 , and  42  allow a ready determination and verification of the location and orientation of the distal tip portion  16  of the LTFMD  10 , of the distal portion  106  of a gastric tube  100  within which it is received, and of the locations of the corresponding openings  108 A,  108 B, and  108 C in a gastric tube  100  as previously illustrated, for instance in  FIGS. 16 through 18 . In each of  FIGS. 20 through 22 , for example, the LTFMD  10  has a first radiopaque marker  36  that is annular and that comprises or is fixed to the most distal tip of the distal tip portion  16 . In  FIG. 20 , the first marker  36  is torroidal while the first marker in  FIGS. 21 and 22  is hemispherical. In each embodiment, coded second, third, and fourth radiopaque markers  38 ,  40 , and  42  are spaced at known distances D 1 , D 1  plus D 2 , and D 1  plus D 2  plus D 3  respectively from the distal end of the LTFMD  10 . 
     In this regard, it is noted that the distance dimensions D 1 , D 2 , and D 3  in the drawings are indicated as measured to the centers of the markers  38 ,  40 , and  42 . Those distance dimensions D 1 , D 2 , and D 3  here correspond to the longitudinal centers of the openings  108 A,  108 B, and  108 C. It will be understood that other measurements, such as to the most distal or proximal portions of the markers  38 ,  40 , and  42 , are possible. 
     In  FIG. 20 , the coded second, third, and fourth radiopaque markers  38 ,  40 , and  42  comprise torroidal rings that are retained to surround the distal tip portion  16  of the LTFMD  10 . The markers  38 ,  40 , and  42  are coded by the physical number of torroidal rings corresponding to the longitudinal position of respective markers  38 ,  40 , and  42  from the most distal tip of the distal tip portion  16 . Accordingly, the second marker  38  at the first distance D 1  and the first longitudinal position spaced from the most distal tip of the tip portion  16  as defined by the first marker  36  comprises one ring, the third marker at the combined distances D 1  and D 2  and the second longitudinal position spaced from the first marker  36  comprises two rings, and the fourth marker at the combined distances D 1 , D 2 , and D 3  and the third longitudinal position spaced from the first marker  36  comprises three rings. 
     In the embodiment of the LTFMD  10  of  FIG. 21 , however, the coded radiopaque second, third, and fourth markers  38 ,  40 , and  42  comprise circumferentially spaced series of the numerical characters “1,” “2,” and “3” of radiopaque material embedded in the distal tip portion  16  corresponding to the first, second, and third longitudinal positions spaced from the most distal tip of the tip portion  16  as defined by the first marker  36 . 
     Finally, in the embodiment of the LTFMD  10  of  FIG. 22 , the coded radiopaque second, third, and fourth markers  38 ,  40 , and  42  comprise circumferentially spaced series of the Roman numerals “I,” “II,” and “III” of radiopaque material embedded in the distal tip portion  16 . The second, third, and fourth markers  38 ,  40 , and  42  correspond to the first, second, and third longitudinal positions spaced from the most distal tip of the tip portion  16  as defined by the first marker  36 . 
     While multiple different types of coded radiopaque markers  36 ,  38 ,  40 , and  42  are illustrated, it will be understood that numerous other possible coded markers  35 ,  38 ,  40 , and  42  would be obvious to a person of skill in the art after reviewing the present disclosure. All such embodiments are within the scope of the invention, except as it may be expressly limited by the claims. As shown by these illustrative embodiments, markers  36 ,  38 ,  40 , and  42  may be of sizes, shapes, locations, and relative positions that enable a practitioner to identify each marker  36 ,  38 ,  40 , and  42  and to distinguish therebetween. Based on this ability to identify and distinguish between markers  36 ,  38 ,  40 , and  42  readily through x-ray imaging, a practitioner can accurately determine the exact location and orientation of the distal tip portion  16  of the LTFMD  10  and the distal portion  106  of a gastric tube  100  in which it is received. Moreover, by the known spacing of the coded second, third, and fourth radiopaque markers  38 ,  40 , and  42  at known distances D 1 , D 1  plus D 2 , and D 1  plus D 2  plus D 3  respectively from the distal end of the LTFMD  10 , a practitioner can readily establish with certainty the locations of openings  108 A,  108 B, and  108 C through the wall of the gastric tube  100 . The markers  36 ,  38 ,  40 , and  42  could be formed as inlays or attachments to the outer wall surface of the LTFMD  10 , or they could pass entirely through and form a part of the body of the LTFMD  10 , or they could be formed or attached in some other manner. By their distinctive shapes, the markers  36 ,  38 ,  40 , and  42  are readily distinguished medical wires, leads, and other articles visible during x-ray imaging thereby preventing the misinterpretation of x-ray imaging results and reducing dangers to patients. 
     In one use of the LTFMD  10  with radiopaque markers  26 ,  38 ,  40 , and  42  retained by the distal portion  16  thereof, a gastric tube  100  can be inserted into a nose or mouth of a patient and advanced with the intent of disposing the distal portion  106  of the gastric tube  100  within the stomach of the patient. The LTFMD  10  can be fully inserted into the gastric tube  100  prior to or after placement of the gastric tube  100  within the patient. Then, with the LTFMD  10  fully inserted and left in place, x-ray imaging can be employed to verify or document the placement of the distal tip portion  16  of the LTFMD  10  and, based thereon, the placement of the distal portion  106  of the gastric tube  100  and the opening or openings  108 ,  108 A,  108 B, and  108 C therein by reference to the radiographically visualized locations and orientations of the radiopaque markers  36 ,  38 ,  40 , and  42 . Through the ascertained location of the markers  36 ,  38 ,  40 , and  42 , the locations and orientations of the openings  108 ,  108 A,  108 B, and  108 C or other particular portions of the gastric tube  100  and of the distal portion  106  of the gastric tube  100  in general are known without uncertainty or doubt. 
     As in earlier embodiments of the invention, the LTFMD  10  incorporating radiopaque markers  36 ,  38 ,  40 , and  42  can further retain a pH sensor array  15  as previously shown and described. In the embodiments of  FIGS. 16 through 18 , for example, a pH sensor array is retained that comprises three pH swabs or sensors  18 ,  20 , and  22  with each incorporating a pH indicator. The pH indicators of the sensors  18 ,  20 , and  22  can be the same or different, calibrated to check for the same liquid or different liquids. The sensors  18 ,  20 , and  22  can be retained in any manner, such as by being attached to the distal tip portion  16  of the LTFMD  10  by glue, adhesive paper, spray adhesive, or any known method capable of bonding the two together. The sensors  18 ,  20 , and  22  can be retained adjacent to, within, or on the radiopaque markers  36 ,  38 ,  40 , and  42  as shown, for instance, in  FIGS. 16 through 18 . As previously disclosed, the multiple pH sensors  18 ,  20 , and  22  can be calibrated to test for the same body fluid, such as stomach fluid, or for different body fluids, such as lung fluid and stomach fluid. 
     As set forth herein, after a gastric tube  100  is blindly inserted into a patient but before it can be used, there are three critical issues concerning its placement that must be answered, ideally in sequential order and as soon as possible. The first is whether the gastric tube  100  is kinked, twisted, coiled, or otherwise compromised. The second is whether the gastric tube  100  is improperly located, such as within a lung. The third is whether the distal portion  106  of the gastric tube  100  is located properly in the stomach. Advantageously, each embodiment of the LTFMD  10  disclosed herein is capable of providing a practitioner with certain, verifiable answers to each of the foregoing issues thereby representing a marked advance in patient safety and in the efficacy of gastric tube placement and use. 
     It will be understood that terms of orientation, nomenclature, and other conventions used herein merely provide a complete understanding of the disclosed invention and are not limiting. Other conventions may be used without limitation of the teachings herein. Furthermore, the various components disclosed herein are merely illustrative and are not limiting of the invention. For example, except as limited by the claims, each of the components and steps discussed herein may include subcomponents or substeps that collectively provide for the structure and function of the disclosed component or step. Still further, one or more components or steps, sometimes referred to as members or otherwise herein, could be combined as a unitary structure or a single step while still corresponding to the disclosed components or steps. Additional components and steps that provide additional functions, or enhancements to those introduced herein, may be included. For example, additional components, steps, and materials, combinations of components, steps, or materials, and perhaps the omission of components, steps, or materials may be used to create embodiments that are nonetheless within the scope of the teachings herein. 
     When introducing elements of the present invention or embodiments thereof, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive such that there may be additional elements other than the listed elements. As used herein, the term “example” or “exemplary” is not intended to imply a superlative example. Rather, such terms refer to an embodiment that is one of many possible embodiments. 
     With certain details and embodiments of the present invention for methods and apparatuses for assisting, checking, and confirming nasogastric and orogastric tube insertion and placement disclosed, it will be appreciated by one skilled in the art that numerous changes and additions could be made thereto without deviating from the spirit or scope of the invention. This is particularly true when one bears in mind that the presently preferred embodiments merely exemplify the broader invention revealed herein. Accordingly, it will be clear that those with major features of the invention in mind could craft embodiments that incorporate those major features while not incorporating all of the features included in the preferred embodiments. 
     Therefore, the following claims shall define the scope of protection to be afforded to the inventor. Those claims shall be deemed to include equivalent constructions insofar as they do not depart from the spirit and scope of the invention. A plurality of the following claims may express, or be interpreted to express, certain elements as means for performing a specific function, at times without the recital of structure or material. As the law demands, any such claims shall be construed to cover not only the corresponding structure and material expressly described in this specification but also all legally-cognizable equivalents thereof.