System, method, and apparatus for detecting tube misplacement in a patient's airway

Tube tip detection systems, enteral tubes, and methods for detecting tube misplacement in a patient's airway are provided. For example, a tube tip detection system comprises an enteral tube having a tip, a first sensing component disposed at the tip, and a feedback display. Feedback from the first sensing component is displayed on the feedback display to indicate to a user of the tube tip detection system whether the tip is misplaced in a patient's airway. Similarly, an enteral tube comprises a tip, a length, and a sensing component. The sensing component is a micro-electro-mechanical system (MEMS) infrared carbon dioxide sensor. Further, a detection method comprises embedding a carbon dioxide sensing component into an enteral tube, inserting the enteral tube into the patient through the patient's nose or mouth, and monitoring feedback from the carbon dioxide sensing component to determine if the enteral tube is traveling into the patient's airway.

FIELD

The present subject matter relates generally to a system, method, and apparatus for administering fluids to body cavities and, more particularly, to such systems, methods, and apparatus utilizing a carbon dioxide sensor to detect whether a tube is incorrectly inserted into a patient's airway.

BACKGROUND

Physicians and other health care providers frequently use catheters, which include tubes inserted into the human body, to treat patients. A nasogastric (NG) tube is one type of tube that is placed in the gastrointestinal tract for patients experiencing a variety of ailments. NG tubes are placed through the nasal cavity and are intended to traverse through the esophagus down into the stomach and into the small bowel, if desired. As the tube travels through the oropharynx and hypopharynx, the anatomy splits into the trachea and the esophagus. Tubes commonly are misplaced into the trachea, which can result in pneumonia, pneumothoraces, or even death. As such, there is a critical need for a way to determine when the tube has taken the path of the trachea as opposed to the desired path of the esophagus.

In some cases, health care providers use X-ray machines to gather information about the location of the catheters within the body. There are several disadvantages in using X-ray machines. For instance, X-rays from these machines are a known carcinogen, if received in sufficient doses. Also, X-ray machines are relatively large and heavy, consume a relatively large amount of energy, and may expose the patient to a relatively high degree of radiation. Moreover, these machines are typically not readily accessible for use because, due to their size, they are usually installed in a special X-ray room. This room can be relatively far away from the patient's room. Therefore, health care providers may find it inconvenient to use these machines for their catheter procedures. Further, it can be inconvenient to transport these machines to a patient's home for home care catheter procedures. As such, X-ray confirmation of the tube tip position may be performed only when the position is uncertain, and the enteral tube position more commonly is checked by assessing the pH of tube aspirate. However, it can be difficult to determine a practical pH cutoff level for reliable confirmation of NG tube placement, particularly for pediatric patients.

In other cases, electromagnetism is used to monitor the location or position of the enteral tube tip. For example, an electromagnetic stylet inserted into the patient's body with the enteral tube may provide real-time location information on the tube tip placement within a patient's anatomy. A receiver unit outside the body detects an electromagnetic field transmitted by the stylet and provides on-screen visualization and, thereby, immediate feedback on tube placement. Nevertheless, due to, e.g., variation in placement of the receiver unit and user misinterpretations of the feedback from the electromagnetic stylet, a health care provider can fail to recognize a misplacement of the enteral tube tip within the patient's airway.

Thus, recognition of the airway when placing an enteral tube is an important way to prevent harm to a patient, and the art is continuously seeking new and improved systems, apparatus, and methods for determining a location of a tip of a catheter, such as an NG tube, being inserted into a patient. For instance, an improved enteral tube, such as an NG tube, incorporating means for detecting carbon dioxide to determine whether the enteral tube is being improperly inserted in a patient's airway would be useful. More particularly, embedding one or more CO2sensors in an enteral tube, such as an NG tube, for detecting the CO2concentration along the path of the tube would be desirable. Further, incorporating a micro-electro-mechanical system (MEMS) that detects CO2in a range of the CO2 concentration in a person's exhaled breath into, e.g., the tip of the enteral tube would be useful. Additionally, systems for conveying feedback from such carbon dioxide sensors to a health care provider would be beneficial. Moreover, methods for detecting a tube misplacement in a patient's airway utilizing such carbon dioxide sensors would be advantageous.

SUMMARY

In one aspect, the present subject matter is directed to a tube tip detection system that comprises an enteral tube having a tip, a first sensing component disposed at the tip, and a feedback display. Feedback from the first sensing component is displayed on the feedback display to indicate to a user of the tube tip detection system whether the tip is misplaced in a patient's airway. It should also be understood that the system may further include any of the additional features as described herein.

In another aspect, the present disclosure is directed to an enteral tube that comprises a tip, a length, and a sensing component. The sensing component is a micro-electro-mechanical system (MEMS) infrared carbon dioxide sensor. It should also be appreciated that the enteral tube may further include any of the additional features as described herein.

In yet another aspect, the present disclosure is directed to a method for detecting a tube misplacement in a patient's airway. The method comprises embedding a carbon dioxide sensing component into an enteral tube, inserting the enteral tube into the patient through the patient's nose or mouth, and monitoring feedback from the carbon dioxide sensing component to determine if the enteral tube is traveling into the patient's airway. It should also be understood that the method may further include any of the additional features as described herein.

DETAILED DESCRIPTION

Reference will now be made in detail to one or more embodiments of the invention, examples of the invention, examples of which are illustrated in the drawings. Each example and embodiment is provided by way of explanation of the invention, and is not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. It is intended that the invention include these and other modifications and variations as coming within the scope and spirit of the invention.

Generally, the present subject matter provides catheters for intubating patients having one or more sensing components for sensing carbon dioxide to determine, using the carbon dioxide concentration sensed by the sensing component(s), whether the catheter is being inserted into the patient's airway. Certain catheters are inserted into through the patient's nose or mouth and extend into the patient's gastrointestinal tract and, thus, also may be referred to as enteral catheters or enteral tubes. More particularly, enteral tubes inserted through the patient's nose are called nasogastric (NG) tubes, which typically are feeding tubes. The feeding tube tip, through which a fluid flows into the patient, is disposed in the stomach or intestines, and a feeding source delivers liquid nutrient, liquid medicine, or a combination of the two to the patient. Because erroneous placement of the tube tip may injure or harm the patient, particularly if the tube is misplaced into the patient's airway, it is important to place the tip of the tube at the proper location within the patient's body. Thus, the present subject matter provides enteral tubes having one or more carbon dioxide sensors, which continuously sense carbon dioxide as the enteral tube is inserted into a patient such that a user (such as a health care provider) can determine whether the enteral tube is being misplaced into the patient's airway, where the carbon dioxide concentration is increased compared to the carbon dioxide concentration in the correct placement area, the patient's esophagus and gastrointestinal tract. Further, the present subject matter provides systems and methods for detecting a tube misplacement in a patient's airway.

Referring now to the drawings,FIGS.1A and1Billustrates a tube tip detection system100having an enteral tube102that includes a proximal end or head104and a distal end or tip106. The enteral tube102has a length L between the proximal end104and the tip106. Further, the enteral tube102should have an appropriate diameter and be sufficiently flexible for insertion through, e.g., a patient's nose or mouth and into the patient's gastrointestinal tract. For instance, the enteral tube102should have a size within a range of five to seven French (5 Fr to 7 Fr) for pediatric patients and within a range of ten to twelve French (8 Fr to 12 Fr) for adult patients.

In exemplary embodiments the enteral tube102is a nasogastric (NG) tube, which, through a process called nasogastric intubation, is inserted through a patient's nose into the patient's stomach. In other exemplary embodiments, the enteral tube102is an orogastric (OG) tube inserted during orogastric intubation through the patient's mouth into the stomach. Alternatively, the tube tip106may extend into the patient's intestines rather than the stomach. Whether the tip106is disposed in the stomach or intestines may depend on, e.g., the specific needs of the patient. For typical nasogastric intubations or orogastric intubations, the tube tip106should be in a sub-diaphragmatic position in the stomach, e.g., at least ten (10) centimeters (cm) beyond the gastro-esophageal junction (GOJ), also known as the oesophagogastric junction, which is the part of the gastrointestinal tract where the esophagus and stomach are joined.

As discussed herein, misplacement of the tip106in the patient's airway, e.g., the bronchi or the lungs, rather than in the patient's gastrointestinal tract is a complication of nasogastric or orogastric intubation. To avoid such misplacement, the present subject matter provides enteral tubes102with sensing components to detect whether the tube tip106is being misplaced in the patient's airway. In the depicted embodiment, a first sensing component108is disposed at the tip106, and a feedback display110is disposed at the head104. In exemplary embodiments, the first sensing component108is a micro-electro-mechanical system (MEMS) component, which provides a miniaturized sensor having appropriate dimensions to be embedded in a wall112of enteral tube102at its tip106. More specifically, silicon-based MEMS sensors can be fabricated in small sizes, such as in micrometer (μm) to millimeter (mm) sizes, in clean rooms and then embedded in enteral tubes102. Feedback from the first sensing component108is displayed on the feedback display110to indicate to a user of the tube tip detection system100whether the tip104is misplaced in a patient's airway or is properly placed in the patient's esophagus or gastrointestinal tract. The user may be a health care provider, such as a physician, clinician, nurse, etc.

The MEMS component108includes one or more MEMS active and passive components that form a non-dispersive infrared (IR) sensor. Carbon dioxide (CO2) strongly absorbs infrared radiation at a wavelength of 4.3 μm. Further, the CO2concentration at the end of a person's exhaled breath is approximately 5% to 6% of the exhaled air, which corresponds to about 35 mmHg to about 45 mmHg. Therefore, the MEMS infrared sensor is configured to detect CO2to determine whether the enteral tube is being misplaced in the patient's airway and may be referred to as a MEMS infrared carbon dioxide sensor108. More particularly, the MEMS component108includes an IR emitter108aand an IR receiver108b, which form the MEMS infrared carbon dioxide sensor108. The IR emitter108aemits infrared radiation, and the IR receiver108breceives any reflected radiation. An IR path length between the IR emitter108aand the IR receiver108bdictates the CO2concentration the IR carbon dioxide sensor108can detect. Thus, the MEMS component108, particularly the IR emitter108aand IR receiver108b, should be constructed such that the sensor108can detect a CO2concentration of at least 30 mmHg to 50 mmHg and, in particular embodiments, of at least 35 mmHg to 45 mmHg.

Based on the reflected IR radiation, the tube tip detection system100determines how much IR radiation was absorbed by the air surrounding the enteral tube102and thereby determines the CO2concentration of the air within a pathway114(FIG.4) being traversed by the tube102. In some embodiments, if the CO2concentration is at least 30 mmHg, the tube tip detection system100may determine that the tip106of the enteral tube102is being misplaced in the patient's airway. In other embodiments, the tube tip detection system100may determine that the tip106of the enteral tube102is being misplaced in the patient's airway if the CO2concentration is at least 35 mmHg. That is, the first sensing component108, or MEMS infrared carbon dioxide sensor108, embedded in the enteral tube102near its tip106is configured to sense a CO2concentration of at least 30 mmHg, or in other embodiments, of at least 35 mmHg, which corresponds to the low end of the typical range of CO2concentration in a person's exhaled breath. When the sensing component108senses such a CO2concentration, the sensing component108provides feedback of the CO2concentration to the user via the feedback display110. In some embodiments, the feedback from the sensing component108indicates the tip106is entering the airway when the CO2concentration sensed by the sensing component108is 30 mmHg or 35 mmHg. In other embodiments, if the CO2concentration continues to rise past 30-35 mmHg as the enteral tube102is advanced into the patient, as shown on the feedback display110, the user may determine that the enteral tube102is being incorrectly placed in the patient's airway because the rising CO2concentration likely corresponds to the patient's respirations conveyed through the patient's airway. Stated differently, using the CO2level or concentration that is detected by the first sensing component108, the user can determine whether the enteral tube tip106resides in the patient's airway.

FIGS.2and3illustrate other exemplary embodiments of the tube tip detection system100. As shown, in some embodiments, the enteral tube102includes a plurality of sensing components that are spaced apart from one another along the length L of the tube102. As described above, each sensing component of the plurality of sensing components is a carbon dioxide sensor for detecting the CO2concentration in the air along the pathway traversed by the enteral tube102through the patient. More particularly, the embodiment illustrated inFIG.2comprises the first sensing component108disposed at the tube tip106and a second sensing component116disposed along the length L at a position spaced apart from the tip106. For example, the second sensing component116may be disposed at a midpoint of the tube length L, i.e., halfway between the proximal end104and the tip106. In other embodiments, such as depicted inFIG.3, a third sensing component118also is disposed along the tube length L at a position spaced apart from the tip106.

As shown inFIG.3, to embed the sensing components108,116, and/or118in the enteral tube102, in some embodiments a channel122is defined in the tube102during fabrication of the tube102. Then, the first sensing component108, the second sensing component116, and/or the third sensing component118is disposed within the channel122. Next, a filler material (not shown) is disposed within the channel122around the first, second, and/or third sensing components108,116,118such that the sensing component(s)108,116,118are embedded within the enteral tube102. The sensing components108,116,118may be embedded within the tube102in other ways as well.

In some embodiments, like the exemplary embodiment ofFIG.3, the first sensing component108, the second sensing component116, and the third sensing component118are unequally spaced apart from one another. That is, the distance, or portion of the tube length L, between the first and second sensing components108,116is different from the distance between the second and third sensing components116,118. In other embodiments, the first sensing component108, the second sensing component116, and the third sensing component118are equidistant from one another, i.e., the distance between the first and second sensing components108,116is the same as the distance between the second and third sensing components116,118. Also as illustrated inFIG.3, in some embodiments the first sensing component108may not be disposed at the tip106of the enteral tube102but may be disposed along the tube length L such that the first sensing component108is spaced apart from the tip106. In such embodiments, no sensing component may be disposed at the tip106; that is, in some embodiments of the tube tip detection system100, one or more sensing components are disposed on the tube102at a distance from the tube tip106, with no sensing component disposed right at the tip106. Thus, a variety of placements or positions for the one or more sensing components may be used in various embodiments of the tube tip detection system100.

Further, in exemplary embodiments, each of the first, second, and third sensing components108,116,118is a MEMS infrared carbon dioxide sensor. The miniaturized sensors located on the tip106and/or other locations of the enteral tube102detect a CO2pattern in the air within the passage traversed by the tube102. Because the enteral tube102has a known length L, the CO2pattern (a waveform, as the CO2concentration rises and falls with the patient's respirations, typically three (3) to four (4) respirations per minute) determines if the tube102has deviated to the patient's airway. Stated differently, the amount or length of the enteral tube102that has been inserted into the patient together with the CO2concentration detected by the sensor(s)108,116,118convey to a user of the tube tip detection system100whether the tube tip106is near the patient's airway and is possibly entering the patient's airway rather than continuing down the pathway toward the patient's stomach or intestines, the intended destination of the tube tip106. For example, it is known that bifurcation of the pathway114into the esophagus and the trachea, as illustrated inFIG.4, occurs at a certain distance from the entrance to the nostril in a patient, with the certain distance varying between pediatric and adult patients. Knowing this distance for a given patient, as well as the length L of the enteral tube102, the user can determine how much (or what length) of the tube102has been inserted into the patient and, thus, know whether the tube tip106is at or near the point where the trachea branches off from the pathway114, from which the tube102could be misplaced into the patient's airway.

As an example, bifurcation typically occurs around 18-20 cm from the entrance to the nostril in adults; the area where bifurcation occurs may be referred to as a bifurcation zone120, which is depicted inFIG.4. Thus, for nasogastric intubation of an adult patient, if the CO2concentration begins to increase when approximately 18 cm of the length L of the enteral tube102has been inserted into the patient, the user of the system100can conclude that the tube tip106is at or near the bifurcation zone120. If the CO2concentration continues to increase as the tube102is further inserted, the user may determine that the tube tip106is or has entered the patient's airway and can correct the tube's position within the patient before continuing to insert the tube102. If, however, the CO2concentration does not continue to increase past the bifurcation zone120, the user may determine that the tube tip106is continuing on the correct pathway114(i.e., the tube106is within the esophagus rather than the trachea) to the patient's stomach or bowel.

Accordingly, the one or more sensing components108,116,118likely would register, and display on the feedback display110, an elevated CO2concentration as the tip106of the enteral tube102nears the bifurcation zone120. Thus, the user should monitor the CO2pattern to distinguish between an appropriately placed tube tip106and a misplaced tube tip106. The CO2concentration for an appropriately placed tip106should decrease upon further insertion of the tube past the bifurcation zone120, but the CO2concentration for a misplaced tip106should increase as a greater length of the tube102(greater than the length of tube102to reach the bifurcation zone120) is inserted into the patient.

In some embodiments, e.g., as shown inFIG.1B, the feedback display110is attached to the enteral tube102, but in other embodiments, e.g., as shown inFIG.1A, the feedback display110is separate from and not attached to the enteral tube102. The feedback display110displays the actual CO2concentration detected by the one or more sensing components108,116,118. Additionally or alternatively, the feedback display110displays a non-numerical visual indicator of the CO2concentration, such as one or more colors, symbols, or words. As an example, the visual indicator may comprise a plurality of light emitting diodes (LEDs), such as green, yellow, and red LEDs. In such embodiments, the feedback display110illuminates the green LED(s) if the sensed CO2concentration is below a typical low value of the CO2concentration of a person's exhaled breath (e.g., if the CO2concentration is below 30 mmHg), illuminates the yellow LED(s) if the CO2concentration is within a typical low range of the CO2concentration of a person's exhaled breath (e.g., if the CO2concentration is at or between 30 mmHg to 40 mmHg), and illuminates the red LED(s) if the CO2concentration increases beyond an initial reading at the low end of typical CO2concentration in a person's exhaled breath. As another example, the feedback display110may illuminate a series of colored or non-colored LEDs or display words or symbols to indicate various states of the sensed CO2concentration (e.g., below low end, at low end, or increasing beyond low end of typical CO2concentration of a person's exhaled breath). In still other embodiments, the feedback display110may utilize audible feedback, such as one or more beeping or other sounds, in addition to or in lieu of visual feedback to convey to the user of the system100CO2concentration sensed by the one or more sensing components108,116,118disposed on the enteral tube102.

The present subject matter also provides methods for detecting a tube misplacement in a patient's airway. Referring now toFIG.5, an exemplary method200is illustrated. The method200comprises embedding a carbon dioxide sensing component108into an enteral tube102, as shown at202inFIG.5. The enteral tube102is configured as described herein, having a proximal end104and a tip106separated by a length L of tubing. Moreover, the sensing component108may be a MEMS-based infrared carbon dioxide sensor as described above. As shown at204inFIG.5, the method200also includes inserting the enteral tube102into the patient through the patient's nose or mouth. Thus, the enteral tube102may be a nasogastric or orogastric tube as described herein. Further, as shown at206and208inFIG.5, the method200includes monitoring feedback from the carbon dioxide sensing component108to determine if the enteral tube102is traveling into the patient's airway and, if so, then adjusting the location of the tube tip106such that it is no longer in the patient's airway. The feedback may be displayed on a feedback display110as described herein.

It will be appreciated that, in other embodiments, the method200may accommodate other configurations of the tube tip detection system100as described in greater detail herein. For example, step202of the method200may comprise embedding a plurality of sensing components into the enteral tube102, e.g., a first and second sensing component108,116as illustrated inFIG.2or a first, second, and third sensing component108,116,118as illustrated inFIG.3. Of course, the method200may vary to include other configurations of the apparatus and system described herein.

Accordingly, the present subject matter provides a system and apparatus for detecting a tip of an enteral tube as it is inserted into a patient. In exemplary embodiments, the system uses MEMS sensor(s) on the tube to detect elevated levels of CO2if the tube is inserted into the airway instead of traveling past the bifurcation of the patient's trachea from the patient's esophagus toward the gastrointestinal tract. The system may utilize a single MEMS-based infrared carbon dioxide sensor disposed on the tip of the tube to sense the CO2concentration within the pathway being traversed by the tube. In other embodiments, the system utilizes a plurality of MEMS-based infrared carbon dioxide sensors disposed along the length of the tube to sense the CO2concentration within the pathway being traversed by the tube. The system provides feedback to the user of the system, e.g., a physician, clinician, nurse, or other caregiver, via a feedback display or other device for receiving feedback from the one or more sensing components such that the user can determine whether the tube tip is appropriately placed or is misplaced. Methods for detecting whether the tube tip is misplaced also are provided. Such methods, systems, and apparatus can help reduce the occurrence of misplaced enteral tubes, such as nasogastric or orogastric feeding tubes, thereby reducing complications from administering fluid to a patient through a misplaced tube. Further, the methods, systems, and apparatus described herein reduce such misplacements in a cost-efficient and time-efficient manner. More particularly, the carbon dioxide sensors described herein are a relatively low-cost solution and are easily embedded in enteral tubes during the manufacture of the tubes. Moreover, the system described herein allows real-time, bedside verification of the tube placement, which can save time and money, e.g., compared to existing systems that require tube placement to be verified by x-ray or the like. Other benefits and advantages of the present subject matter also may be recognized by those of ordinary skill in the art.

It should also be appreciated that these procedures may involve treatment of humans by physicians, physician assistants, nurses, or other health care providers. In addition, these procedures may involve treatment of other mammals and animals by veterinarians, researchers, and others.