Device and method for nasogastric tube insertion guidance

Abstract

An apparatus for identifying a nasogastric tube position includes a pump selectively fluidly coupled with the nasogastric tube, a pressure sensor identifying a pressure of an internal chamber of the nasogastric tube, and a controller configured to selectively power the pump and read the pressure sensor to identify an impedance of at least one opening of the nasogastric tube.

Description

[0001] Cross-reference to related applications

[0002] This disclosure claims the benefit of U.S. Provisional Application No. 63 / 100,763, filed on March 30, 2020, entitled “Apparatus and Method for Nasogastric Tube Insertion Guide,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the proper insertion of a nasogastric tube, and more specifically to an apparatus and method for guiding the proper insertion of a nasogastric tube by generating and monitoring pressure therein. Background Technology

[0004] This disclosure relates to the insertion of medical tubes, such as, but not limited to, nasogastric tubes, and particularly their proper entry into the stomach via the esophagus. Patients who cannot be fed in the conventional manner may require a nasogastric tube (hereinafter “NGT”) to deliver nutrition into the stomach. Typically, an attempt is made to insert an NGT without using advanced imaging systems, such as X-ray machines, during insertion. Instead, verification that the distal end of the tube is correctly positioned in the stomach is performed after the NGT has been assumed to be positioned in the stomach. Routine verification techniques include: aspiration of gastric contents and pH measurement; X-ray tracking; auscultation while forcing a small amount of air through the tube; and measuring the pH of the distal end of the tube in the stomach, etc. These techniques are often messy, expensive, dangerous (i.e., radiation exposure during X-rays), and uncertain.

[0005] Improper insertion of a nasogastric tube can cause injury and food contamination of the respiratory system. Therefore, it is desirable to provide guidance to caregivers so that the NGT is inserted into the esophagus on its way to the stomach without entering the trachea. Summary of the Invention

[0006] This disclosure applies principles of gas and fluid dynamics, as well as anatomical structures. These principles are used to guide NGT into the stomach.

[0007] One objective of this disclosure is to ensure that the NGT is inserted into the esophagus early in the insertion process, on its way to the stomach. Early identification of esophageal entry prevents the NGT from entering the trachea and lungs excessively, thus preventing damage associated with improper NGT placement. NGTs must be used to feed patients, whether humans or animals, when nutrition cannot be obtained through routine means. Caregivers may find that using an NGT is the preferred option for providing nutrition to a patient. The NGT must be inserted safely and effectively. If the tube is pushed into the trachea instead of the esophagus, damage can occur during tube insertion, and food contamination can cause more serious damage to the respiratory system.

[0008] Another object of the present disclosure is to determine if the NGT is being advanced into the esophagus or trachea early in the procedure. Thus, if the NGT is being advanced into the trachea, it can be withdrawn and the procedure restarted in order to properly direct the NGT into the esophagus, thereby avoiding causing damage to the respiratory system and adjacent tissue. Nutrients are deposited through the proximal end of the NGT and released into the stomach through the eye-like opening on the side of the distal end of the NGT. It is therefore necessary to direct the NGT through the esophagus into the stomach.

[0009] The present disclosure takes into account the anatomically different characteristics of the esophagus and trachea, both of which can be accessed from the nasal cavity. The esophagus is a muscular tube that connects the pharynx and stomach. The tubular structure of the esophagus is normally in a collapsed state until it is distended by nutrient intake or other external means. The trachea is a large membranous tube reinforced by cartilaginous rings. It connects the larynx to the bronchi and down into the lungs. The trachea is an open structure so as not to impede breathing.

[0010] The NGT has an eye-like opening on the side of the distal end of the tube. When inadvertently placed in the trachea, it is loosely surrounded by the trachea and air flow through the NGT is not impeded in either direction of flow. One feature of the present disclosure is that when inserted into the esophagus, the tube is surrounded by the inner wall tissue of the esophagus, thus impeding air flow in both directions.

[0011] In one aspect of the present disclosure, the difference in air flow resistance values is a consideration during NGT insertion guidance when the tube is in the trachea versus the esophagus. Furthermore, once the NGT reaches the stomach, the air flow resistance is slightly lower than in the esophagus and can be used to confirm entry into the stomach. If the NGT is advanced further into the duodenum (i.e., small intestine), the resistance to air flow can change further.

[0012] Another aspect of the present disclosure is to detect a kinked NGT that can occur during tube insertion. A kinked NGT has a reduced effective length, i.e., a trapped air volume between the kink location and the device. This reduced air volume will further increase the measured air flow resistance with respect to the air flow resistance when the tube is in the esophagus. One aspect of the present disclosure includes marking the NGT at the length from the nose to the ear and then to the stomach. During insertion, the markings can be used to identify the positioning of the NGT.

[0013] In another aspect of the present disclosure, when the stomach marker reaches the nose after passing through the esophagus, the air flow resistance is expected to decrease. No change in air flow resistance indicates a kinked NGT. Similarly, the NGT can be marked to indicate when it reaches the low neck point. When this marker reaches the nose during NGT insertion, the NGT is either in the esophagus or in the trachea, and thus the difference in air flow resistance must be noted.

[0014] In another aspect of the disclosure, calibration is performed by simulating conditions in the esophagus with the eye of the tube blocked. In yet another aspect of the disclosure, a quick calibration procedure is performed on each individual NGT, overcoming differences in tube parameters while compensating for loose device components and assembly tolerances.

[0015] In another aspect of the disclosure, a "Whoosh Test" is performed in which air is injected into the tube while the stomach region is auscultated. As part of this test, the whoosh sound confirms that the tube is in the stomach.

[0016] Another aspect of the disclosure is sensing air flow impedance in the NGT through repeated instantaneous measurements in order to minimize internal friction while advancing the tube. The measurements can be performed in a sequential manner, but other measurement patterns do not depart from the scope of the disclosure.

[0017] Another option of the disclosure is air flow impedance monitoring in a suction mode. In the suction mode, impedance differences are more pronounced.

[0018] In yet another aspect of the disclosure, air flow determination based on pressure in the NGT is performed for each instantaneous air flow sensing event.

[0019] Another aspect of the disclosure involves maintaining low pressure build-up by letting the pressure reach a predetermined level and recording the time it takes to reach that level. In this way, the pressure does not exceed the predetermined level before the air flow impedance measurement (suction and injection) stops.

[0020] In another aspect of the disclosure, a numerical and / or graphical curve display of the time it takes to reach a predetermined pressure for each measurement can be performed. In addition, light and / or audio indicators can be used instead of or in addition to the display.

[0021] Yet another aspect of the disclosure is the use of a thin probe inserted into the tube lumen to verify hydrochloric acid in the stomach. The chemical reaction of the material at the tip of the probe with the gastric fluid changes the appearance of the tip of the probe. This confirms that the distal end of the tube is inside the stomach.

[0022] Another aspect of the disclosure is a chemical and its derivative compounds used with the probe that are non-toxic in the human digestive tract.

[0023] Another aspect of the disclosure is stiffening the tube with the probe while inside the lumen, thereby providing an advantage in advancing the tube.

[0024] In yet another aspect of the disclosure, an optional protective filter is located between the NGT and the device.

[0025] One embodiment of the present disclosure is a device for identifying a nasogastric tube position. The device can have a pump configured to selectively fluidly couple with a nasogastric tube, a pressure sensor configured to identify a pressure of an internal chamber of the nasogastric tube, and a controller configured to selectively power the pump and read the pressure sensor to identify a resistance of at least one opening of the nasogastric tube.

[0026] One example of this embodiment has a filter positioned to filter fluid passing between the pump and the nasogastric tube. Another example has a pressure releaser configured to selectively fluidly couple the internal chamber of the nasogastric tube to ambient.

[0027] In yet another example of this embodiment, the controller has a pressure threshold stored therein. In one aspect of this example, the controller has a calibration routine stored therein and the controller selectively executes the calibration routine to determine a time threshold for generating the pressure threshold.

[0028] In another example, the pump is intermittently operated. In another example, the controller is configured to determine an air flow resistance based on a pressure time factor. In yet another example, the controller is configured to stop the pump when the pressure sensor identifies a predetermined pressure is reached. In yet another example, the controller is configured to determine the air flow resistance based on a time it takes for the pump to generate a threshold pressure in the internal chamber.

[0029] Another embodiment of the present disclosure is a method of manufacturing a device for identifying a nasogastric tube position. The method includes positioning a pump to selectively move fluid through a coupler configured to selectively fluidly couple to a nasogastric tube. The pump is configured to selectively move fluid into or out of an internal chamber of the nasogastric tube when fluidly coupled with the internal chamber of the nasogastric tube; the method also includes fluidly coupling a pressure sensor between the pump and the coupler to selectively identify a pressure of the internal chamber when coupled with the nasogastric tube. Another part of the method is communicatively coupling a controller with the pump and pressure sensor to provide instructions to selectively power the pump and selectively identify the pressure of the internal chamber. This method also contemplates programming the controller to selectively power the pump and measure the pressure of the internal chamber when fluidly coupled with the nasogastric tube to identify a resistance of an opening of the nasogastric tube.

[0030] One example of this embodiment includes programming the controller to discontinue powering the pump if the pressure of the internal chamber does not satisfy a pressure threshold after a predetermined amount of time of powering the pump. Part of this example includes programming a calibration procedure in the controller to establish a time threshold for a particular nasogastric tube. Another part of this example includes programming the controller to store the time threshold established during the calibration and use the time threshold as the predetermined amount of time.

[0031] Another example of this embodiment includes providing a user input in communication with the controller and configured to be engaged by the user when the nasogastric tube is in a predefined position within the patient. Part of this example includes programming the controller to power the pump and monitor the pressure sensor when the user input is engaged.

[0032] Yet another example of this embodiment includes programming the controller to be in communication with a stop button, wherein the controller is configured to not power the pump when an input from the stop button is identified.

[0033] Yet another embodiment of the present disclosure is a method of identifying positioning of a nasogastric tube in a stomach of a patient. The method includes fluidly coupling a nasogastric tube with a pump, selectively powering the pump to change a pressure in an internal chamber of the nasogastric tube, monitoring the pressure in the internal chamber while the pump is powered, and identifying a location of an opening of the nasogastric tube by determining an impedance of the opening.

[0034] In one example of this embodiment, the impedance is determined by monitoring a time interval of powering the pump and the pressure in the internal chamber. In another example, the impedance is determined at least twice while the nasogastric tube is inserted into the stomach of the patient. BRIEF DESCRIPTION OF DRAWINGS

[0035] The above aspects of the present disclosure and the manner in which they are attained will become more readily apparent from the following description of embodiments of the present disclosure, reference being made to the accompanying drawings, in which:

[0036] Figure 1 is a cross-sectional view showing a trachea and an esophagus;

[0037] Figure 2 is a cross-sectional view showing a NGT connected with a NGT insertion guide via a protective filter according to the present disclosure;

[0038] Figure 3a is a cross-sectional view showing a NGT insertion guide of Figure 2

[0039] Figure 3b ​This is another detailed block diagram of an embodiment of the present disclosure;

[0040] Figure 4 The attached figure shows the distal end of an NGT having an eye-shaped opening for delivering nutrients into the stomach;

[0041] Figure 5 This is an attached diagram of a probe used to identify hydrochloric acid in the stomach;

[0042] Figures 6a-6c This is a logic flowchart of one embodiment of the present disclosure;

[0043] Figure 7 This is a block diagram of the manufacturing method disclosed herein;

[0044] In several views, corresponding reference numerals are used to indicate the corresponding parts. Detailed Implementation

[0045] For the purpose of facilitating understanding of the principles of this disclosure, reference will now be made to the embodiments described herein and illustrated in the accompanying drawings, and these will be described using specific language. However, it should be understood that this disclosure is not intended to limit its scope, and such changes and additional modifications in the illustrated apparatus and methods, as well as such additional applications of the principles of this disclosure as shown therein, are things that would normally occur to those skilled in the art as per the scope of this disclosure.

[0046] The details shown herein are merely examples and are intended only for illustrative discussion of embodiments of this disclosure, and to present a description that is considered most useful and readily understood in terms of the principles and concepts of this disclosure. In this regard, no attempt is made to show the details of this disclosure in more detail than is necessary for a basic understanding of it, and the description in the accompanying drawings makes it clear to those skilled in the art how this disclosure can be implemented in practice.

[0047] Figure 1 The diagram illustrates a cross-section 300 of the trachea and esophagus. The walls of the trachea 305 are reinforced with cartilage rings that maintain the lumen 310 of the trachea and allow unobstructed airflow for breathing. When a nasogastric tube or NGT 200 (see...) is used... Figure 3a When inserted into the trachea 305, the airflow in the NGT 200 is unobstructed in either direction.

[0048] The lumen 325 of the generally collapsed esophagus 320 typically at least partially obstructs airflow. The lumen 325 can expand due to, but not limited to, food / drink, air injection, and medical devices. When the NGT is inserted into the esophagus 320, the lumen 325 surrounds the NGT, at least partially obstructing the distal end eye-like opening 162 of the NGT (see...). Figure 3b). Thus, when the opening 162 of the NGT 200 is located in the esophagus 320, air flow in the NGT 200 is generally at least partially impeded. The present disclosure contemplates identifying air impedance into the opening 162 of the NGT 200 as an indication of the distal end 164 of the NGT 200 in the gastric tract (i.e., the esophagus 320), and can be advanced into the stomach, etc.

[0049] Figure 2 A top level assembly 100 of the NGT insertion guide 202 is illustrated, hereinafter referred to as the "device." The device 202 is connected to the NGT 200 through a filter 120. In one aspect of the present disclosure, the device 202 measures air flow impedance in the NGT 200, etc.

[0050] Figure 3a A detailed functional block diagram of the NGT insertion guide 202 is illustrated, including an optional filter 120 coupled to the NGT 200. The filter 120 provides protection against contamination from one patient to another, etc. The filter 120 herein is defined as a passive filter such as a membrane or an active filter that physically separates the tube from the device 202 when the flowing air can contain contaminants, pathogens, etc. This functional block diagram illustrates one configuration as an example, but other configurations and connection modes do not depart from the scope of the present disclosure. More specifically, the present disclosure contemplates using any known filtration method to separate the NGT 200 from the device 202 to avoid potential cross-contamination between patients. Further, in another implementation contemplated herein, there can be no filter 120 at all.

[0051] A pressure source such as, but not limited to, a pump 105 can selectively deliver air flow to the NGT 200. The pump 105 is controlled by a pump controller 125. Further, a trigger 130 can selectively activate the device 202 through the pump controller 125 and the pump 105. Air flow in the NGT 200 is activated and impedance is measured by identifying a combination of pressure in the NGT 200 and pump 105 action time (i.e., volume of air pumped). In other words, the present disclosure contemplates identifying pressure time factors (i.e., air pressure and volume) of the NGT 200 to identify a relative location of the distal end of the NGT 200 in the patient.

[0052] Figure 3b Another block diagram of the present disclosure is illustrated. Figure 3bThe pump 105 is illustrated as being fluidically coupled with the pressure releaser 115 via a conduit 152. However, the pressure releaser 115 can also be coupled directly with the pump 105. Regardless, the pressure releaser 115 can be coupled with the filter 120 through a filter coupler 145 or directly with the NGT 200 through an NGT coupler 150. Further, other embodiments contemplated herein can not have a pressure releaser at all and the NGT 200 can be coupled directly with the conduit 152 through the NGT coupler 150. The NGT 200 can be coupled with the filter 120 (or directly with the pressure releaser 115 or the conduit 152 in alternative embodiments) through the NGT coupler 150, such that the inner chamber 154 of the NGT 200 is fluidically coupled to the filter 120, the pressure releaser 115, the conduit 152, and the pump 105, as in the example embodiment of Figure 3b In this configuration, the pump 105 can pump fluid into or out of the inner chamber 154 through the conduit 152, the pressure releaser 115, and the filter 120.

[0053] The pump 105 can have a pump bore 156 that provides fluid input or output for the pump 105 to the ambient environment or atmosphere 158. When the pump 105 adds fluid to the inner chamber 154, the pump bore can draw air or other fluid from the ambient environment 158 and into the inner chamber 154. Further, in another embodiment, the pump 105 can draw fluid from the inner chamber 154 and expel the fluid into the ambient environment 158. Similarly, the pressure releaser 115 can have a release bore 160 that allows the pressure releaser 115 to selectively fluidically couple the inner chamber 154 to the ambient environment 158.

[0054] The NGT 200 can be substantially isolated from the ambient environment 158 except through one or more openings 162 at the distal end of the NGT 200. In a typical NGT 200, the openings 162 are intended to be positioned within the stomach to direct nutrients into the stomach.

[0055] A controller 166 can communicate with and / or control one or more components of the device 202. More specifically, the controller can selectively power the pump 105 to move fluid into or out of the inner chamber 154. Further, the controller 166 can communicate with the pressure sensor 110 to identify the fluid pressure in the inner chamber 154. Similarly, the controller 166 can control the pressure releaser to selectively fluidically couple the inner chamber 154 to the ambient environment 158, etc. Alternatively, the pressure releaser 115 can be preset to release pressure when the inner chamber 154 generates a pressure outside of a preset pressure release pressure.

[0056] Airflow impedance can be measured by bringing the pressure to a predetermined value and determining the time it takes for the pressure to reach that level. A shorter time corresponds to a higher impedance. Alternatively, the pump 105 can pulse at a constant pulse duration, and the pressure established can correspond to the air flow impedance in the NGT 200. More specifically, a higher pressure reading can correspond to a higher air flow impedance. The air flow impedance can be determined by the following equation:

[0057] A = P / T

[0058] Formula I

[0059] In equation I, the air flow impedance is A, the pressure is P, and the time is T. In equation I, the time T represents the volume of air V pumped at a constant pumping rate. The pressure threshold and the time (volume) threshold are two opposing choices. However, a combination pattern between the pressure and time thresholds is also contemplated herein and within the scope and spirit of the present disclosure. In one aspect of the present disclosure, the pump 105 can be a piston-based pump, and the pressure P can be derived linearly from the driving force F of the pump. In this example, the driving force F threshold can replace the P threshold in equation I.

[0060] In one example, when the pressure in the NGT 200 reaches a predetermined pressure level, the pressure threshold 135 is satisfied and the pump controller 125 stops the pump 105. At the same time, the device 202 can record the time it takes for the pump 105 to reach the threshold pressure 135 on the timer display 140, or otherwise store the recorded time on a storage unit for further processing. The time indicated on the timer display 140 or otherwise stored in the device 202 corresponds to the level of air flow impedance. If the pressure threshold 135 is not identified by monitoring the pressure sensor 110 within a predetermined interval or cutoff time, the pressure threshold 135 can communicate with the pump controller 125 to stop the pump 105. At the same time, the device 202 can identify the time it takes for the pump 105 to stop (numerically, graphically, by audio or light). In one example, the time can be displayed on the timer display 140. The time indicated on the timer display 140 can correspond to the level of air flow impedance and can represent a low impedance in this example.

[0061] In one application of the present disclosure, when the opening 162 of the NGT 200 is located in the nasal cavity of the user, the impedance will be very low. However, when the opening 162 of the NGT 200 is advanced to approximately the level of the user's neck, the distal end of the NGT 200 will enter the esophagus 325 or trachea 310 upon further advancement. If the timer display 140 indicates a high air flow impedance when the NGT 200 is in this position, it is evidence that the opening 162 of the NGT 200 has entered the lumen 325 of the esophagus and can continue to be advanced into the stomach. Once in the stomach, an instantaneous drop in air flow impedance can further confirm the location of the opening 162 of the NGT 200. However, if the air flow impedance does not increase as the NGT 200 is advanced further down the user's neck, the opening 162 at the distal end of the NGT 200 can be in the trachea 310. This indicates that the healthcare provider should pull back on the NGT 200 to avoid positioning the NGT 200 at least partially incorrectly in the user's lungs.

[0062] A kinked NGT 200 can occur during the tube insertion procedure. If the NGT 200 is kinked during insertion, the distal end of the NGT 200 can not reach the stomach properly. In one aspect of the present disclosure, the back of the throat can be visually inspected for a kink in the NGT 200. In one aspect of the present disclosure, the NGT 200 can be measured and marked prior to insertion into the patient. More specifically, a measurement on the NGT 200 can be identified that represents the distance from the nose via the earlobe to the stomach. The NGT 200 is marked so that during insertion, when the stomach mark of the NGT 200 is at the nose, the distal end and opening 162 of the NGT 200 should be in the stomach.

[0063] When the stomach mark of the NGT 200 reaches the nose and the distal end of the NGT 200 reaches the stomach, a decrease in air flow impedance is generally evident. This can indicate a kink in the NGT 200 when the air flow impedance is perceived to be passing through the esophagus and the inserted NGT 200 length mark indicates that the stomach has been reached but the pulse duration remains the same. More specifically, if the mark on the NGT 200 indicates that the opening 162 should be in the stomach, the impedance of the NGT 200 should be relatively low. If the impedance does not decrease at this length, a kink in the NGT 200 can cause a higher than expected impedance.

[0064] A kinked NGT 200 has a reduced effective length, i.e. the volume of air trapped in the NGT 200 between the kink location and the device 202. This reduced air volume will significantly increase the measured air flow impedance relative to the air flow impedance when the tube is in the esophagus. Thus, one aspect of the present disclosure contemplates identifying a kink in the NGT 200 when the impedance is higher than expected.

[0065] NGTs are available in different French sizes (or diameters) and lengths from multiple manufacturers. They are made from many different materials with various properties. A brief calibration of the device 202 to each NGT 200 can be performed to compensate for all potential differences in NGT design. Furthermore, the tolerances of the components used in the manufacture of the device 202 can be relaxed as they will also be compensated for by the calibration.

[0066] In one calibration method, when the opening 162 is in the esophagus, the opening 162 of the NGT 200 can be occluded while simulating the conditions of the NGT 200. This calibration procedure can record the action and duration of the pump 105 while occluding the opening 162 of the NGT 200. From this pulse duration, the expected pulse duration to the trachea and stomach can be mathematically derived. In other words, the expected pulse duration of the relative high impedance when the opening 162 is in the esophagus and the relatively low impedance when the opening 162 is in the trachea can be generated based on the pulse duration identified when the opening is occluded.

[0067] In another aspect of the disclosure, a "burp test" can be used to confirm that the opening 162 of the NGT 200 is in the stomach. For the burp test, a small amount of air is injected into the NGT 200 while a healthcare professional auscultates the stomach region. The "burp" sound identified by the healthcare professional indicates that the NGT 200 is in the stomach. This method is an effective way to periodically reassure the healthcare professional that the opening 162 of the NGT 200 has not moved from the stomach back into the esophagus. If no burp sound is detected, the NGT 200 can be inserted further into the user until a burp sound is detected.

[0068] Figure 4 Examples of other implementations of the opening 162 considered herein are illustrated. Openings 215 and 225 are illustrated at the distal end of NGTs 210 and 220. The eye-like opening 225 shows an optional protective member 230 that prevents occlusion. Alternatively, two eye-like openings on opposite sides of the distal tube wall would avoid such occlusion. However, other implementations can have four transverse eye-like openings distributed around the NGT 200. This feature enables the NGT 200 to be exposed to air in the trachea even in the presence of an endotracheal tube or the like. More specifically, due to the small available area for manipulation, it can not be possible to positively determine the location of the opening 215 before reaching the endotracheal cuff. However, when the opening 215 of the NGT 200 passes the cuff and before reaching the lungs, it will be exposed to air and a lower air flow impedance in the NGT 200 will be identifiable using the device 202 discussed herein.

[0069] Figure 5It is illustrated that in one example the diameter of the slim probe 410 can be about 0.5 mm. The length of the probe 410 can exceed the length of the NGT 200. The tip 420 of the probe 410 is coated with a thin layer of a chemical such as but not limited to magnesium oxide (“MgO”) or tin oxide (“SnO”) that changes color as it reacts with gastric fluid such as hydrochloric acid (“HC1”). When the probe is removed from the lumen, a visual inspection is performed to determine if a color change has occurred. If the tip 420 changes color, it indicates that it came into contact with gastric fluid through the opening 162 on the distal end of the NGT 200. This confirms that the opening 162 of the NGT 200 reached the stomach regardless of the pH level of the stomach contents.

[0070] An alternative method for verifying that the opening 162 of the NGT 200 has reached the stomach is an optical sensor that can be integrated with the device 202. Two bundles of optical fibers 430 can be coated with a thin layer of a chemical such as but not limited to MgO or SnO 420 that changes color as it reacts with gastric fluid such as HC1. The other end of the fiber is attached to an optical transceiver 440 that includes a light source and a light sensor. Both MgO and SnO are white and reflect light at a high intensity before reacting with HC1 acid. Upon meeting HC1 in the stomach, MgCl2 is transparent and SnCl2 is black and reflect light at a low intensity. Other non-toxic chemicals with similar properties can also achieve the same result.

[0071] Both the manual probe 410 and the optical fiber probe 430 must have the chemical 420 firmly adhered and any adhesive used must be porous so that the acid can reach the chemical 420 and show as transparent or translucent and the color of the chemical 420 can be observed, respectively.

[0072] If the stomach is full from a previous meal and indicates a neutral pH level, then the air flow impedance measurement will indicate a lower impedance than in the esophagus. Alternatively, verification can be performed after the stomach contents are digested. Yet another alternative is to perform a visual verification by aspirating the stomach contents and detecting the acidity, color, etc.

[0073] Reference is now made to Figures 6a-6cFIG. 6 illustrates one embodiment of a logic flow diagram 600 for implementing the present disclosure. In this embodiment, the device 202 can be initiated at a power on or other start function illustrated in block 602. The device 202 can be coupled with the NGT 200 to utilize pressure changes and fluid flow to determine the location of the opening 162 at the distal end of the NGT 200, as discussed herein. After starting at 602, the device 202 can instantaneously release any pressure in the NGT 200 or otherwise established in the device 202 in block 604. The pressure release of block 604 can ensure that the pressure within the NGT 200 is equal to atmospheric pressure. As discussed herein, one aspect of the present disclosure contemplates a relative pressure change within the NGT 200 after the pump 105 has processed a volume of fluid into or out of the NGT 200. Thus, the pressure release of block 604 can ensure that the pressure within the NGT 200 is equal to the surrounding atmosphere prior to propulsion.

[0074] While explicit pressure release functions are discussed herein, other embodiments can not implement a pressure release function and instead assume that the NGT 200 has an internal pressure equal to the environment 158 prior to performing the logic flow diagram 600.

[0075] The pump 105, timer, and audio / video components such as the display 140 can be powered in block 606. This can include engaging the pump 105 with the pump controller 125 to pump a volume of fluid into or out of the lumen 154 of the NGT 200 coupled with the device 202. Substantially simultaneously, a timer can be initiated to identify the length of time that the pump 105 has actively pumped. As the pump 105 pumps fluid to or from the NGT 200, the pressure indicated by the pressure sensor 110 can be compared to a pressure threshold in block 608.

[0076] At block 608, the measured pressure of the NGT 200 can be compared to a predetermined pressure threshold. The predetermined pressure threshold can be a typical pressure generated by the pump 105 when the distal end of the NGT 200 is at least partially obstructed. The predetermined or pre-determined pressure threshold can be a minimum threshold pressure that is high enough to effectively perform the logic flow diagram 600. In one example, the predetermined pressure threshold can be approximately 5 mmHg. However, in other examples contemplated herein, the predetermined pressure threshold can be greater or less than 5 mmHG and can vary slightly depending on the particular application. In one aspect of the present disclosure, the predetermined threshold pressure can be as low as possible to minimize the impact on soft tissue surrounding the opening 162 as fluid is pumped into or out of the lumen 154.

[0077] If the pressure measured in block 608 is not greater than the pressure threshold, the timer can be considered in block 610 to determine whether the run time of the pump 105 is less than the cutoff time threshold. If the pump 105 has only been running for an amount of time that is less than the cutoff time threshold, the pump 105 can continue to run and the pressure is monitored in block 608. However, if the cutoff time is greater than the cutoff time threshold in block 610, or the pressure threshold is reached in block 608, the recorded time of the timer can be displayed on the timer display 140 in block 612. In block 614, the pump 105, the timer, and the audio can be turned off. In block 616, the stop button can be monitored. If the stop button is engaged, the device 202 can terminate the logic flow diagram 600. However, if the stop button is not engaged in block 616, the logic flow diagram 600 can perform the instantaneous pressure release of block 604, as discussed herein, and continue through blocks 606, 608, 610, 612, 614, and 616.

[0078] In yet another aspect of the logic flow diagram 600, the device 202 can have an input that allows the user to identify when the neck marker on the NGT 200 is located at the nose. As discussed herein, a neck marker can be created on the NGT 200 at a location that represents the length of the NGT 200 that is inserted through the nose before entering the esophagus. Thus, block 620 can be used to direct the identification of when the neck marker is at the nose. If the neck marker is identified at the nose at 620, the user can select the neck button on the device 202 at 622, indicating the positioning of the NGT 200. When the neck button is selected in block 622, the neck function 624 can be implemented.

[0079] The neck function 624 is illustrated in more detail in Figure 6b The neck function 624 is illustrated in more detail in

[0080] However, if the pressure in the NGT 200 does reach the pressure threshold at or before the cutoff threshold time, it can indicate that the opening 162 in the distal end is properly positioned in the esophagus. Thus, in block 632, the user can continue to advance the NGT 200 along the esophagus toward the stomach. In addition, a stomach marker can be positioned on the NGT 200 to indicate when the NGT 200 can be positioned in the stomach, as discussed herein. Thus, the user can continue to advance the NGT 200 into the patient until the stomach marker is located near the nose in block 634. At this point, the distal opening at the end of the NGT 200 should be located within the stomach. Thus, in block 638, the pressure in the NGT 200 can be monitored to determine whether the opening in the distal end of the NGT 200 is in the stomach. More specifically, in block 638, if the pump 105 does not require more time to generate the threshold pressure in the NGT 200, it can indicate that the NGT 200 is kinked at block 640. At this point, the device 202 can provide a warning or notification regarding the kink.

[0081] However, if the time to pressurize the NGT 200 is increased in block 638, it can indicate that the opening at the distal end of the NGT 200 is located in the stomach and is substantially unobstructed. Thus, in block 642, it can be determined that the opening at the distal end of the NGT 200 is in the stomach and an indication identifying the opening can be provided by the device 202. Once the distal end is identified as being in the stomach, the pump 105, timer, and any audio or visual indicators can be turned off in block 644. The user can also select a stop button at 646 to terminate the neck function 624.

[0082] The device 202 can also have a stop function 648 that can be selectively engaged by the user or the controller. In block 650, the stop function 648 can automatically terminate any logic loops currently being implemented by the device 202. In addition, the stop function 648 can also reset all values and thresholds in block 652. Finally, the stop function 648 can terminate at 654 and the device 202 can be ready for subsequent use.

[0083] Referring now to Figure 6c , a logic flow of a calibration procedure 660 is illustrated. The calibration procedure 660 can be implemented to identify the time it takes for the internal region 154 of the NGT 200 to reach a predefined pressure when the opening 154 on the distal end of the NGT 200 is substantially obstructed. In one aspect of the disclosure, different types of NGT 200 can be coupled with the device 202. Different types of NGT 200 can have different internal volumes, lengths, and stiffness, among others. Thus, the calibration procedure 660 can be implemented to establish an expected time threshold for the NGT 200 to meet an expected pressure level.

[0084] In one aspect of the disclosure, the pump 105 can pump at a substantially consistent flow rate. Thus, the amount of time it takes for a pressure threshold to be generated within the NGT 200 can depend at least in part on the volume of the internal chamber of the NGT 200. The calibration procedure 660 discussed herein allows the device 202 to establish a particular time threshold for a particular NGT 200 with which it is coupled by determining the amount of time it takes for the internal chamber of the NGT 200 to reach a pressure threshold based on the substantially fixed flow rate of the pump 105.

[0085] More specifically, in block 662, a user can select a calibration button. Alternatively, in one embodiment, the calibration procedure 660 can be implemented automatically by the device 202 upon coupling of a new NGT 200 with the device. Regardless, the calibration procedure 660 should be implemented when the NGT 200 is fluidly coupled with the device 202 and one or more openings at the distal end of the NGT 200 are substantially occluded. Once the NGT 200 is coupled with the device 202 and the distal end is substantially occluded, a pressure release function can be implemented in block 664. The pressure release function of block 664 can utilize the pressure releaser 115 of the device 202 discussed herein to equalize the pressure within the internal chamber 154 of the NGT 200 with the ambient atmosphere 158. More specifically, the pressure releaser 115 can be a valve between the internal chamber of the NGT 200 and the ambient atmosphere 158 that is temporarily opened in block 664.

[0086] After the instantaneous pressure release, the pressure releaser 115 can close, substantially isolating the internal chamber 154 of the NGT 200 from the ambient atmosphere 158. Once the pressure releaser 115 is closed, the pump 105 and a timer can be initiated in block 666. The timer can be an internal timer on the controller of the device 202 or identified from a separate timing component. Regardless, the timer can record the amount of time that the pump 105 is engaged or otherwise powered. Further, in one aspect of the disclosure, an audio or visual indicator can be initiated when the pump 105 is engaged in block 666.

[0087] Once the pump 105 is powered in block 666, the pressure sensor 110 can be monitored in block 668 to determine when the pressure of the lumen of the NGT 200 reaches a predefined pressure threshold. The pressure sensor 110 can be fluidly coupled with the internal chamber 154 of the NGT 200 to identify the pressure therein. Further, the predefined pressure threshold can be a pressure that is greater or less than the surrounding atmospheric pressure. In other words, the pump 105 can pump fluid into or out of the internal chamber 154 of the NGT 200. If the pressure identified by the pressure sensor 110 is not within the predefined pressure threshold, the pump 105 can continue to pump fluid to or from the lumen of the NGT 200. However, once the pressure sensor 110 identifies a pressure that is within the predefined pressure threshold, the time that the pump 105 takes to generate the pressure in the internal chamber of the NGT 200 is recorded as data and displayed on the timer display 140 in block 670.

[0088] After the time that the pump 105 takes to generate the pressure within the predefined pressure threshold in the NGT 200 is established, the pump 105 and the timer can be turned off in block 672. The calibration procedure 660 can then determine whether the number of time readings reaches a predefined count in block 674. In other words, the calibration procedure 660 can perform blocks 664, 666, 668, 670, and 672 multiple times in order to identify an average time that the pump 105 takes to generate the pressure within the pressure threshold of the NGT 200. Thus, in block 674, if the number of times recorded does not satisfy the predetermined count, blocks 664, 666, 668, 670, and 672 will be repeated. In other words, the calibration procedure 660 can continue to perform blocks 664, 666, 668, 670, and 672 until the number of times recorded reaches the predetermined count. Figure 6c In non-exclusive examples, three separate time readings can be recorded before proceeding to block 676. However, other embodiments contemplate taking fewer or more time readings.

[0089] Once the predetermined number of counts is reached in block 674, the average time that the pump 105 takes to generate the predefined pressure will be determined in block 676. This can include determining the average time based on all of the recorded times in the data. Once the average time is calculated in block 676, the average time can be saved in the data as a reference for the time threshold used in blocks 610 and 628, among others, in block 678. In block 680, the display 140 or other visual or audio device can indicate that the calibration procedure has completed. Once the user is notified in block 680 that the calibration procedure is complete, the calibration procedure 660 can terminate in block 682.

[0090] The calibration procedure 660 discussed herein can be used to calibrate the pump 105 to generate a pressure within the pressure threshold of the NGT 200. In other words, the calibration procedure 660 can be used to determine the average time that the pump 105 takes to generate the pressure within the pressure threshold of the NGT 200. This average time can then be used to determine the time threshold used in blocks 610 and 628, among others. Figures 6a-6cThe logic discussed herein can be executed by one or more controllers in electrical communication or otherwise in communication with the device 202. The controller or controllers can include a processor for executing commands and processing data, among other things. Further, the controller or controllers can have a storage unit that can store data or can access a storage unit that can store data. In one example, the controller is in electrical communication with the device 202. The pump 105 is selectively powered by the controller based on the logic discussed herein (i.e., the controller activates the pump controller 125). Further, the controller is in communication with the pressure sensor 110 to identify the pressure of the internal chamber 154 of the NGT 200 when fluidly coupled thereto. The controller can also selectively control the position of the pressure releaser 115. The controller of the device 202 can also receive user input from any input device such as the test trigger 130 and display or otherwise generate indicators to the user through the timer display 140 or other audio or visual components that can be partially controlled by the controller.

[0091] The pump 105 is discussed herein as pumping fluid into or out of the NGT 200. The term "fluid" can refer to a gas or liquid state or a combination thereof. In one example, the pump 105 pumps gas from the ambient atmosphere into the NGT 200. Alternatively, the pump 105 can pump gas out of the NGT 200. Further, the pump 105 can be a controlled source of air flow, such as a compressed air reservoir or the like, for providing air into or out of the NGT 200.

[0092] While specific devices and methods are discussed herein, other devices and methods can be utilized to implement the teachings of the present disclosure. More specifically, any device capable of moving fluid into or out of an NGT can be used to implement these teachings. The time it takes for the device to reach a predetermined pressure can be monitored to identify the impedance at the opening of the NGT. Alternatively, the volume of fluid removed from or added to the NGT before reaching a predetermined pressure can be monitored to identify the location of the opening of the NGT.

[0093] Referring now to Figure 7 FIG. 13 illustrates one example of a method of manufacturing a device 700 of the present disclosure. The method of manufacturing 700 includes positioning a pump to selectively move fluid through a coupler configured to selectively fluidly couple to a nasogastric tube in block 702. The pump can be the pump 105 and the coupler can be the coupler 145 or 150 depending on whether a filter is included. When the pump 105 is coupled to the coupler, the pump is positioned to fluidly couple to the NGT to selectively move fluid into or out of the internal chamber 154 of the nasogastric tube 200 when fluidly coupled thereto.

[0094] The method of manufacture 700 can include fluidly coupling a pressure sensor between the pump and the coupler to selectively identify the pressure of the inner chamber when coupled with the nasogastric tube 200 in block 704. The pressure sensor can be the pressure sensor 110 and can be fluidly coupled with any portion of the conduit between the pump and the NGT 200, etc.

[0095] In block 706, the controller can be communicatively coupled with the pump and the pressure sensor to provide instructions to selectively power the pump and selectively identify the pressure of the inner chamber. The controller can be the controller 166 and can have a wired connection to selectively power the pump or the pump controller. Alternatively, the controller can wirelessly communicate with the pump or the pump controller to selectively power the pump. Similarly, the controller can communicate with the pressure sensor through a wired or wireless communication scheme.

[0096] In block 708, the controller can be programmed to selectively power the pump for a predetermined amount of time when fluidly coupled with the nasogastric tube and measure the pressure of the inner chamber to identify the impedance of the opening of the nasogastric tube with the teachings considered herein. In one embodiment, the controller is programmed to discontinue powering the pump if the pressure of the inner chamber does not satisfy a pressure threshold after the predetermined amount of time of powering the pump as discussed herein. Further, the controller can have a calibration program programmed therein to establish a time threshold for a particular nasogastric tube. In this embodiment, the controller can store the time threshold established during calibration and use the time threshold as the predetermined amount of time.

[0097] Portions of the method of manufacture 700 can include providing a user input in communication with the controller. The user input can be user selectable when the nasogastric tube is in a predefined position within the patient. The controller can also be programmed to power the pump and monitor the pressure sensor when the user input is engaged. The method of manufacture can also include programming the controller to be in communication with a stop button, where the controller is configured to not power the pump when input from the stop button is identified.

[0098] Referring now to Figure 8 , a method of identifying the position of the NGT 800 with the teachings of the present disclosure is provided. More specifically, the method includes fluidly coupling a nasogastric tube with a pump such as the pump 105 discussed herein 802. The pump can then be selectively powered to change the pressure in an inner chamber of the nasogastric tube 804. The pressure in the inner chamber can be monitored when the pump is powered 806. Information about the duration of powering the pump and the pressure of the inner chamber can be considered to identify the position of the opening of the nasogastric tube 808. More specifically, the duration of the pump and the pressure can be utilized to determine the impedance of the opening.

[0099] As part of the method 800, impedance can be determined by monitoring the time interval for which the pump is powered and the pressure in the internal chamber. Further, the method 800 can determine impedance at least twice while inserting the nasogastric tube into the stomach of the patient.

[0100] While the foregoing has been particularly described with reference to exemplary implementations in accordance with the principles of the application, this application is not to be taken as being limited to the specific implementations disclosed. Rather, the scope of the application is to be accorded with the broadest interpretation so as to encompass any and all implementations with were using the general principles metioned. Further, the application is to cover variations, alterations, and modifications which can be made to the application by those skilled in the art without departing from the scope of the application as set forth in the appended claims.

Claims

1. An apparatus for identifying a nasogastric tube position, comprising: a pump configured to selectively fluidly couple with a nasogastric tube; a pressure sensor configured to identify a pressure of an internal chamber of the nasogastric tube; and a controller selectively powering the pump and reading the pressure sensor to identify an airflow resistance of at least one opening of the nasogastric tube.

2. The apparatus of claim 1, further comprising a filter positioned to filter fluid passing between the pump and the nasogastric tube.

3. The apparatus of claim 1, further comprising a pressure releaser configured to selectively fluidly couple the internal chamber of the nasogastric tube to an ambient environment. the controller having a pressure threshold stored therein.

4. The apparatus of claim 1, wherein, the controller having a calibration procedure stored therein and the controller selectively executing the calibration procedure to determine a time threshold for generating the pressure threshold.

5. The apparatus of claim 4, wherein, the pump intermittently operating.

6. The apparatus of claim 1, wherein, the controller configured to determine the airflow resistance based on a pressure-time factor.

7. The apparatus of claim 1, wherein, the controller configured to stop the pump when the pressure sensor identifies a predetermined pressure is reached.

8. The apparatus of claim 1, wherein, the controller configured to determine the airflow resistance based on a time the pump takes to generate a threshold pressure in the internal chamber.

9. The apparatus of claim 1, wherein, 10. A method of manufacturing an apparatus for identifying a nasogastric tube position, comprising: positioning a pump to selectively move fluid through a coupler configured to selectively fluidly couple with a nasogastric tube, the pump configured to selectively move fluid into or out of an internal chamber of the nasogastric tube when fluidly coupled with the internal chamber of the nasogastric tube; fluidly coupling a pressure sensor between the pump and the coupler to selectively identify a pressure of the internal chamber when coupled with the nasogastric tube; communicatively coupling a controller with the pump and pressure sensor to provide instructions to selectively power the pump and selectively identify the pressure of the internal chamber; programming the controller to selectively power the pump and measure the pressure of the internal chamber when fluidly coupled with the nasogastric tube to identify an airflow resistance of an opening of the nasogastric tube.

11. The method of claim 10, further comprising programming the controller to discontinue powering the pump if the pressure of the internal chamber does not satisfy a pressure threshold after a predetermined amount of time of powering the pump.

12. The method of claim 11, further comprising programming a calibration procedure in the controller to establish a time threshold for a particular nasogastric tube.

13. The method of claim 12, further comprising programming the controller to store the time threshold established during the calibration and use the time threshold as the predetermined amount of time.

14. The method of claim 10, further comprising providing a user input in communication with the controller and configured to be engaged by the user when the nasogastric tube is positioned at a predefined location within a patient. ​ 15. The method of claim 14, further comprising programming the controller to power the pump when the user input is engaged and to monitor the pressure sensor.

16. The method of claim 10, further comprising programming the controller to communicate with a stop button, wherein, the controller is configured to not power the pump when input from the stop button is identified.

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