Patent ID: 12220544

DETAILED DESCRIPTION

Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

As used herein, the terms “about,” “approximately,” or “generally,” when used to modify a value, indicates that the value can be raised or lowered by 5% and remain within the disclosed embodiment. Further, when a plurality of ranges are provided, any combination of a minimum value and a maximum value described in the plurality of ranges are contemplated by the present invention. For example, if ranges of “from about 20% to about 80%” and “from about 30% to about 70%” are described, a range of “from about 20% to about 70%” or a range of “from about 30% to about 80%” are also contemplated by the present invention.

Generally speaking, the present invention is directed to a tubing assembly that includes a catheter having a proximal end and a distal end and extending in a longitudinal direction, where the proximal end and the distal end define a lumen therebetween. Further, the catheter can be configured for placement within a digestive tract or a respiratory tract of a patient. The tubing assembly also includes an ultrasound transducer. The ultrasound transducer can be located within the lumen of the catheter. The ultrasound transducer can be used in conjunction with an external ultrasound transducer or receiver located on or outside the patient's body. The ultrasound transducer of the tubing assembly can transmit ultrasound signals as directed by a processor, and the external ultrasound transducer can receive ultrasound signals from the ultrasound transducer of the tubing assembly and communicate with a processor to deliver sound data to a display device. A catheter guidance system and a method for accurately placing a catheter in the digestive tract or respiratory tract are also contemplated by the present invention.

The present inventors have found that the tubing assembly, catheter guidance system, and method described in more detail herein allow for the ultrasound data captured in real-time via an ultrasound transducer or receiver positioned just outside the patient's body to be used to determine if the distal end of the catheter is placed within the digestive tract (e.g., the epiglottis, esophagus, stomach, intestines, etc.) rather than placed within the respiratory system (e.g., the trachea, bronchi, lungs, etc.), where such placement could be harmful and even fatal to a patient. Further, the present inventors have found that because the external ultrasound transducer or receiver can obtain measurements and communicate those measurements to processor and ultimately a display device or other communication device (e.g., a phone, pager, etc.) in real time, the placement of the catheter can be confirmed within seconds of a catheter placement procedure, which can save valuable time, resources, and cost while at the same time limit patient risk in the event of the erroneous placement of the catheter.

Specifically, the present inventors have found that capturing and monitoring ultrasound data in real-time transmitted from inside or within a catheter to be placed in a predetermined location along the digestive tract (e.g., esophagus, stomach, intestines, etc.), which is facilitated by the ultrasound transducer of the catheter guidance system of the present invention, allows for the efficient and accurate placement of the catheter within the digestive tract at a low cost. For instance, an ultrasound transducer or receiver placed outside the patient's body, e.g., on the throat or xyphoid process, can capture ultrasound data (e.g., ultrasound waves that propagate from the ultrasound transducer at a distal end of the catheter to the external ultrasound transducer or receiver) as the catheter is being directed by a health care provider in to the body of a patient, where the captured ultrasound data can then be transmitted to a display device via a processor. The health care provider can then view the captured ultrasound data on the display device (e.g., on a spectrogram that plots the captured ultrasound data of a graph showing frequency versus time to determine attenuation of the ultrasound signal) to determine if the catheter has been placed in the digestive tract or placed in an anatomical region of the respiratory system (e.g., the trachea, bronchi, lungs, etc.). Alternatively or additionally, a memory device that can include machine readable instructions and one or more computer programs (which, for example, may include a plurality of algorithms) can be used by the processor to process the data from the ultrasound transducer, where the display device can then indicate the catheter information to the health care provider in the form of a signal as to whether the catheter is placed in the digestive tract or placed within, for instance, a portion of the respiratory system. For example, a green check mark or the word “Yes” can be displayed on the screen to indicate accurate placement of the catheter within the digestive or gastrointestinal tract, while a red circle with a diagonal line through it, an “X”, or the word “No” can be displayed on the screen for erroneous placement, such as placement within the respiratory system.

The various features of the catheter guidance system are discussed in detail below.

Referring now to the drawings, in an embodiment illustrated inFIGS.1-4, the catheter guidance system2contemplated by the present invention includes: (a) an apparatus10having a housing18which supports a controller or processor20which may include filter38and a display device22; (b) a power cord27that couples the apparatus10to a power source25; (c) an optional printer28coupled to the apparatus10for printing out paper having graphics which indicate catheter location information; (d) an optional non-invasive movable receiver-transmitter or transceiver32electronically coupled to the processor20by a wire, cable, signal data connection or signal carrier63; and (e) an invasive electronic catheter unit12in communication with and operatively coupled to the apparatus10where the electronic catheter unit12includes a tubing assembly14that includes a catheter50; an ultrasound transducer46; and an optional signal generator58when the system2includes the optional non-invasive movable receiver-transmitter or transceiver32. An external ultrasound transducer or receiver48may additionally be included in the electronic catheter unit12or alternatively separate from but in operative communication with the electronic catheter unit12. The invasive catheter unit12may be an electronic catheter unit that is be operatively coupled to the apparatus10by a wire, cable, cord or electrical extension34, which, in turn, is operatively coupled to the processor20.

As best illustrated inFIG.2, the system2, in one embodiment, includes: (a) a plurality of input devices17for providing input signals to the system2such as one or more control buttons29, a touch screen31, and the optional transceiver32; (b) an ultrasound transducer46that can continuously transmit ultrasound waves from inside or within a catheter50of the tubing assembly14in real-time; (c) an external ultrasound transducer or receiver48that can continuously capture ultrasound data received from the transmitted ultrasound waves from the ultrasound transducer46in real-time; (d) an optional signal generator58which produces or generates electronic signals that are received by the transceiver32; (e) a memory device21including machine readable instructions and one or more computer programs (which, for example, may include a plurality of algorithms23) which are used by the processor20(which may include a filter38) to instruct the ultrasound transducer46to transmit ultrasound waves and to process the ultrasound data captured by the external ultrasound transducer or receiver48as well as to process the signal data produced by the signal generator58and transmitted by the transceiver32if present; and (f) a plurality of output devices19such as the display device22and the printer28which indicate the catheter information to the health care provider, such as in the form of a graph37(seeFIG.1). The display device22may be any suitable display mechanism including, but not limited to, a liquid crystal display (LCD), light-emitting diode (LED) display, cathode-ray tube display (CRT) or plasma screen.

In one particular embodiment, the memory device21can store instructions which, when executed by the processor20, cause the processor20to (i) interpret catheter50location and/or position information as determined and communicated by the ultrasound transducer46and/or the external ultrasound transducer or receiver48and the optional signal generating assembly16and the non-invasive transceiver32, and (ii) cause the processor20to then instruct the system2to alert the health care provider either via the display device22, auditory signals, etc. as to the accurate or inaccurate placement of the catheter50.

Health care providers can use the system2in a variety of catheter applications. In one example illustrated inFIG.3, the system2is used in an enteral application. Here, a portion of the electronic catheter unit12is placed through an orifice72of the patient's body78, such as the patient's nose or mouth. The distal end or tip60of the electronic catheter unit12can ultimately by positioned in the stomach74. As the health care provider advances the catheter50of the electronic catheter unit12towards the patient's stomach74, the ultrasound transducer46can transmit ultrasound waves, e.g., from the distal end60of the catheter50. The ultrasound transducer46can then receive reflected or echoed ultrasound waves, and/or the external ultrasound transducer or receiver48can continuously monitor for ultrasound waves that propagate from the ultrasound transducer46of the catheter50to the external ultrasound transducer or receiver48as the catheter50is inserted by the health care provider, whether the external ultrasound transducer or receiver48is placed on or near the patient's body78, as shown inFIGS.1and3. The display device22and the printer28can indicate information related to the location of the portion of the electronic catheter unit12within the body78based on the ultrasound data acquired by the ultrasound transducer46of the catheter50and/or the external ultrasound transducer or receiver48, as well as information related to the shape of the pathway taken by the catheter unit12if the system includes the signal generator58and the associated non-invasive transceiver32. It should be appreciated that the system2need not indicate the exact location or path of the catheter unit12to provide assistance to the health care provider.

Referring toFIG.4, in one embodiment, the electronic catheter unit12includes a tubing assembly14, which includes the catheter50and the ultrasound transducer46of the present invention, where the catheter50can generally extend in the longitudinal direction L. In one embodiment, the ultrasound transducer46can be disposed within the lumen70of the catheter50at a distal end or tip60of the catheter50, as shown inFIG.4. However, it is also to be understood that the ultrasound transducer46can be located anywhere along the length of the catheter50, so long as the sound waves generated by the transmitter46within the catheter50can reach or be picked up by the external ultrasound transducer48, and the distance from the ultrasound transducer46to the distal end60of the catheter50is known.

As best illustrated inFIGS.4-5, in one embodiment, such as when a wired connection (e.g., a connection via a wire assembly62as opposed to a wireless connection, which is also contemplated by the present invention, where the ultrasound transducer46includes a battery or other source of power) electrically connects the ultrasound transducer46to the processor20, the tubing assembly14can include (a) a tube or an electrical tubular insulator40; (b) a mid-connector or union device42which receives the tubular insulator40; (c) a multi-port connector or y-port connector44attachable to the union device42; (d) a catheter50, such as a feeding tube, connected to the y-port connector44; and (e) a distal end or tip60of the catheter50, where the ultrasound transducer46can be located within the lumen70of the catheter50at the distal end or tip60or anywhere upstream along the length of the catheter50.

In one embodiment, the tubular insulator40includes a tube having a proximal end100attachable to an attachment member or neck108of a controller coupler or electrical connector36and a distal end102receivable by the union device42; and an internal diameter which is substantially equal to or greater than an external diameter of a wire assembly62described below, which can serve as the hard wired electrical connection between the ultrasound transducer46and the processor20, so as to slide over the wire assembly62. In another embodiment, the tubular insulator40may fit relatively tightly over the wire assembly62so as to be secured to the wire assembly62.

As best illustrated inFIG.4, in one embodiment, the union device42includes: (a) a proximal end116; (b) a distal end118; (c) a position adjuster, extender or elongated neck120positioned between the proximal end116and the distal end118; (d) a grasp or gripping member122positioned adjacent to the distal end118so as to assist users in grasping and manipulating the union device42; and (e) an insert124positioned adjacent to the gripping member122which is received by the y-port connector44. When assembled, the proximal end116of the union device42is coupled to the distal end102of the tubular insulator40.

In one embodiment, the multi-port or y-port connector44includes: (a) a body140; (b) a liquid delivery branch, medicine delivery branch or medicine branch142attached to the body140for distributing drugs, medicine or other medicinal liquids to the patient's body78; (c) a nutrient delivery branch or feeding branch144attached to the body140and sized to receive the insert124of the union device42; (d) a catheter or feeding tube connection branch146attached to the catheter50; (e) a flexible or movable arm148attached to the body140; and (f) a flexible or movable arm150attached to the body140. In an alternative embodiment, y-port connector44includes additional branches for administering various nutrients or medicines to the body78. In another alternative embodiment, the y-port connector44includes only a feeding branch144and a connection branch146. The arm148has a stopper152, and the arm150has a stopper154. The stoppers152and154are sized to prevent fluid from passing through the branches142and144after such branches142and144are plugged with stoppers152and154, respectively. In addition, the arm150includes a fastener155which secures a tube-size adapter156to the arm150. The tube-size adapter156enables fluid delivery tubes (not shown) having various diameters to connect to the feeding branch144of the y-port connector44.

As illustrated inFIG.4, in one embodiment, the catheter50includes a feeding tube or catheter50with a body160having a proximal end162attached to the catheter connection branch146of the y-port connector44and a distal end164. The proximal end162is insertable into the catheter connection branch146of the y-port connector44so as to bring the catheter50into fluid communication with the y-port connector44.

As also shown inFIG.4, in one embodiment, the end member, bolus or tip60is attached to the distal end164of the catheter50. The tip60includes a body172having a collar174and an end member176. The body172defines a passage178and an opening180. The opening180is positioned between the collar174and the end member176. A portion177of the end member176can have a rounded shape. The shape of the passage178and opening180of the tip60is configured to facilitate the flow of fluid from the catheter50into the patient's body78while decreasing the likelihood that the opening180will become clogged.

The tubular connector40, union device42, y-port connector44, catheter50, and tip60can be made from any suitable polymer or plastic material including, but not limited to, polyamide, polyethylene, polypropylene, polyurethane, silicone and polyacrylonitrile.

Referring still toFIGS.1and4, when the ultrasound transducer46is located in the lumen70of the catheter50such as at its distal end60, the ultrasound transducer46can be electrically connected to the processor20via an electrical connection in the form of a wire assembly62that runs through the tubular insulator40described above to an electrical connector or controller coupler36, discussed in more detail below. This arrangement can also be used when the electrical connection from the ultrasound transducer46to the processor20is wireless.

Turning now to the specifics of the ultrasound transducer46and referring toFIGS.1,4, and5, a controller coupler or an electrical connector36can be operatively connected to the electrical extension34and an elongated wire assembly62can be operatively coupled to the electrical connector36to form a wired connection between the ultrasound transducer46and the processor20, although it is to be understood that the electrical connection between the processor20and the ultrasound transducer46can also be wireless provided that the ultrasound transducer46has its own power source, such as a battery. Further, a wire or elongated stiffener39can be attached to the connector36and can serve as a support for the wire assembly62when it is inserted into the body160of the catheter50or the tubing66. Further, the tubular insulator40described above can cover a portion41of the wire assembly62positioned adjacent to the connector36in the embodiment where the ultrasound transducer46is positioned within the lumen70of the catheter50. In any event, the electrical connector or controller coupler36can provide the electrical connection between the apparatus10and the ultrasound transducer46when the ultrasound transducer46is hard wired to the catheter guidance system2via the wire assembly62. In other embodiments, the ultrasound transducer46can be in the form of an echogenic material that is configured to transmit and/or reflect ultrasound waves. The echogenic material can be incorporated into the catheter50, e.g., at the tip60of the catheter50. For instance, the ultrasound transducer46can be a piezoelectric bimorph or unimorph configured to function as both a receiver and transmitter of ultrasound energy. The echogenic material or piezoelectric bimorph/unimorph may be mounted to the catheter50on the inside or outside of the catheter50, or may be incorporated into the material of the catheter50itself.

Turning now to the specific configuration for the ultrasound transducer46, although any suitable ultrasound transducer46for transmitting ultrasound waves that propagate from the distal end60of the catheter50that can withstand the environmental conditions of the body can be used in the catheter guidance system2of the present invention, in one particular embodiment, the ultrasound transducer46can be in the form of a transducer having a small footprint such that it can be placed within the lumen70of the catheter50or any other suitable location within the tubing assembly14. The ultrasound transducer46may be any suitable transducer now known or later developed in the art. For example, in one embodiment, the ultrasound transducer46may be a piezoelectric (PZT) transducer. Alternatively, the transducer46may be a capacitive micromachined ultrasonic transducer (CMUT). In yet another embodiment, the transducer46may also include polydimethylsiloxane (PDMS) transducers and/or photoacoustic transducers.

As shown inFIGS.1and3, the external ultrasound transducer48can be placed on or near the patient's body78. For instance, the external ultrasound transducer48can include a housing49and an attachment47. The attachment47can be directly affixed to the subject's body10so that the external ultrasound transducer48maintains a fixed reference point in relation to the patient's body78. Thus, if the patient moves, the external ultrasound transducer48can move with the patient to maintain a static frame of reference with respect to the particular patient. The attachment47can be positioned on a surface of the housing49. For example, the attachment47can include an adhesive material that is configured to affix the housing49to the skin of the subject, a patch on the subject's body, or a garment worn by the subject. The adhesive material can be an adhesive substrate that can be adhesive on both sides such that it adheres to the surface of the housing49on one side and to a subject's body or garment on the other side. When the attachment47is adhesive material adhered to the surface of the housing49, it may additionally include a peelable protective sheet covering the entire adhesive material. The peelable protective sheet can be removed prior to affixing the adhesive attachment47to the patient's body78or the patient's garment. For instance, the attachment47can be similar to an EKG pad in which the attachment47includes an adhesive sheet surrounding the housing49such as in a donut shape. In other embodiments, the attachment47can include a clip, pin, magnet, hook and loop system, or any other suitable means for affixing the housing49of the external ultrasound transducer48to the patient's body78or garment. Further, the attachment47can be or can include ultrasound gel to provide a means for transmission of the ultrasonic energy between the body and the external ultrasound transducer48. The gel could be in the form of a hydrogel adhesive, or it could be applied/dispersed from a bottle during placement of the external ultrasound transducer48.

In any event, by using an attachment47on the external ultrasound transducer48that can affix the external ultrasound transducer48to the patient's body78or garment, the frame of reference of the measurement of the sound waves from the ultrasound transducer46can remain stationary with the patient's body. Alternatively, the external ultrasound transducer48can be placed near the patient's body78, such as at the patient's bedside. In some embodiments, the external ultrasound transducer48may be incorporated into the housing18of the system2.

Turning now to the specific configuration for the external ultrasound transducer48, although any suitable ultrasound transducer48for transmitting and/or receiving data from ultrasound waves that propagate from the ultrasound transducer46in the distal end60of the catheter50that can withstand the environmental conditions of the body can be used in the catheter guidance system2of the present invention, in one particular embodiment, the external ultrasound transducer48can be in the form of any suitable transducer that can be disposed on or near the patient's body78having a small footprint such that it can be placed in a housing49configured to be placed on or near the patient's body78. The external ultrasound transducer48may be any suitable transducer now known or later developed in the art. For example, in one embodiment, the external transducer48may be a piezoelectric (PZT) transducer. Alternatively, the external transducer48may be a capacitive micromachined ultrasonic transducer (CMUT). In yet another embodiment, the external transducer48may also include polydimethylsiloxane (PDMS) transducers and/or photoacoustic transducers. The manner in which the external ultrasound transducer48and the internal ultrasound transducer46function to identify the location of the catheter50is described in more detail below and with reference to Table 1.

TABLE 1Attenuation v. Material at 1 MHzMaterialα⁡(dBMHz·cm)Air, at 20° C.1.64Blood0.2Bone9.94Connective Tissue1.57Fat0.48Muscle1.09Soft Tissue (average)0.54Water0.0022

Ultrasound energy attenuates differently depending on the medium it travels through. For instance, as shown in Table 1 above, cartilage tissue has a higher attenuation factor (α) compared to air and flesh. When the catheter50is located in the trachea92, the catheter50will be surrounded by air, cartilage, and flesh. Notably, the cartilage forms ‘rings’ in the trachea92. In comparison, when the catheter50is located in the esophagus91, the catheter50will be surrounded by flesh and only a small amount of air, if any. Thus, ultrasound energy will be attenuated more within the trachea92due to the higher attenuation factor of cartilage than the attenuation of the same ultrasound energy within the esophagus91.

Additionally, ultrasound energy is direction sensitive. Thus, the positioning of the external ultrasound transducer48relative to the ultrasound transducer46within the catheter50can impact the strength of the ultrasound energy detected by the external ultrasound transducer48. For instance, the external ultrasound transducer48can be placed in a particular fixed location on the patient's body78or near the patient's body78. For example, the external ultrasound transducer48may be placed on the side of the throat of the patient's body78in such a way that both the esophagus91and the trachea92are visible at the same time. The area in which the external ultrasound transducer78is capable of detecting ultrasound energy from within the patient is considered the “detection zone.” The ultrasound transducer46within the catheter50, e.g., at the tip60of the catheter50, must pass through the detection zone in order for the external ultrasound transducer48to receive and detect the generated ultrasound energy from the ultrasound transducer46within the catheter50.

In use, the ultrasound transducer46within the catheter50can be operated to generate ultrasound waves at a selected frequency and intensity such that the external ultrasound transducer48, operating as a sensor or receiver of ultrasound energy, can detect the ultrasound energy generated by the transducer46when the catheter50is in the esophagus91but cannot detect the ultrasound energy generated by the transducer46when the catheter50is in the trachea92. In other words, the selected frequency and intensity generated by the ultrasound transducer46within the catheter50is attenuated by the cartilage of the trachea92so that the ultrasound energy is not detectable when the ultrasound energy reaches the cartilaginous rings, while the ultrasound energy may be detectable when the catheter50is surrounded by air in the trachea92as it moves between cartilaginous rings. In some embodiments, the ultrasound waves can have a frequency ranging from about 20 kilohertz to about 2.5 megahertz, such as from about 25 kilohertz to about 2 megahertz, such as from about 50 kilohertz to about 1.5 megahertz. Further, in some embodiments, a spectrum or band of frequencies can be utilized rather than a single frequency within the aforementioned ranges.

Specifically, the external ultrasound transducer48functioning as a receiver may be able to “see” the catheter50when the catheter50is within the esophagus91, and/or when the ultrasound transducer46of the catheter50is in between the cartilaginous rings of the trachea92(e.g., surrounded by air), but cannot “see” the catheter50when the ultrasound transducer46is behind or attenuated by the cartilaginous rings of the trachea92. The external ultrasound transducer48can then send signals to the processor20relaying the received ultrasound information. The processor20, and specifically one or more algorithms23stored in the memory device21in operative communication with the processor20, can determine if the ultrasound signal generated by the ultrasound transducer46within the catheter50have been attenuated. For instance, attenuation can be determined as a “yes/no” or “pass/fail” determination. Additionally or alternatively, the amount or degree of attenuation can be measured, as a relative percentage of intensity or as an absolute value. The attenuation can be displayed by the display22in order to provide a visual indication of the location of the catheter50.

In some embodiments, the ultrasound transducer46may additionally transmit a reference signal. The reference signal may be transmitted ultrasound energy having a selected frequency and intensity that is detectable when the catheter50is within both the esophagus91and the trachea92. Thus, the reference signal can be used as confirmation that the catheter50is passing through the detection zone where the external ultrasound transducer48is configured to receive the ultrasound energy from the ultrasound transducer46within the catheter50.

In some aspects of the invention, the function of the ultrasound transducer46within the catheter50and the external ultrasound transducer48can be reversed compared to the above-described procedure. The external ultrasound transducer48may generate ultrasound energy from its fixed location. The ultrasound transducer46within the catheter50may then be configured to receive the ultrasound energy generated by the external ultrasound transducer48to determine or measure the attenuation of the generated ultrasound energy. As described above, the ultrasound energy generated by the external ultrasound transducer48may be selected to have a frequency and intensity such that the attenuation by the cartilaginous tissue of the trachea92makes the ultrasound energy undetectable from the trachea92but still remains detectable from the esophagus91. The ultrasound transducer46can then send signals to the processor20relaying the received ultrasound information. The processor20, and specifically one or more algorithms23stored in the memory device21in operative communication with the processor20, can determine if the ultrasound signal generated by the external ultrasound transducer48have been attenuated. For instance, attenuation can be determined as a “yes/no” or “pass/fail” determination. Additionally or alternatively, the amount or degree of attenuation can be measured, as a relative percentage of intensity or as an absolute value. The attenuation can be displayed by the display22in order to provide a visual indication of the location of the catheter50.

In an additional arrangement for using ultrasound to detect the placement of the catheter50, one or both of the ultrasound transducer46within the catheter50and the external ultrasound transducer48can be used to generate an ultrasound image that can be used to identify the location of the catheter50. For instance, the ultrasound transducer46within the catheter50can be used alone (i.e., without being paired with the external ultrasound receiver48) to generate ultrasound waves and receive reflected ultrasound waves to visualize or image the location of the catheter50. Any suitable method of using ultrasound energy for visualizing tissue, e.g., ultrasound pulsing and measuring the reflected or echoed ultrasound waves, may be used. The reflected ultrasound waves within the trachea92have a distinctly different profile resulting in a different visual image compared to reflected ultrasound waves within the esophagus91to enable the user to distinguish between the presence of the catheter50in the trachea92or esophagus91. Specifically, within the esophagus, which is a closed, tissue-dense environment, active ultrasound imaging may generate a glowing image showing the esophageal tissue, whereas the air-filled trachea92may show a dark image due to the air-filled environment. The ultrasound image may be shown on the display22.

Additionally or alternatively, the memory device21may store one or more algorithms23such as machine-learning algorithms that are configured to differentiate between the visual images of esophageal tissue versus tracheal tissue and instruct the processor20what type of tissue in which the catheter50is located. For instance, machine learning algorithms may include mathematical models that are used to use input signals (e.g., data collected from the ultrasound transducer) to produce predictions (e.g., information regarding the position of the catheter). The parameters of these models can be selected based on training data that is collected in advance. Training data used for determining model parameters can be furnished from a-priori measurements from a selection of test subjects or models. Training data may also be collected on a subject-by-subject basis prior to beginning the placement of catheter. Finally, model parameters may be updated in real-time based on data that is collected during the procedure. Some examples of machine learning algorithms and mathematical models include, but are not limited to, decision trees, artificial neural networks, support vector machines, regression analyses, Bayesian networks, genetic algorithms, and deep learning algorithms.

Additionally or alternatively, an ultrasound time-of-flight calculation can be used to determine the location of the catheter50. This can be performed either by the ultrasound transducer46of the catheter50on its own, by calculating the time-of-flight of waves generated and reflected back to the ultrasound transducer46, or by measuring the time-of-flight of ultrasound waves generated by one of the ultrasound transducer46or the external ultrasound transducer48and received by the other respective ultrasound transducer. For instance, the processor20can send at least one time-stamped signal, e.g., at least one or a series of signals in the form of alternating current (AC), at a known frequency to the ultrasound transducer46. By “time-stamped,” the present invention contemplates recording the precise time that each respective signal is sent from the processor20to the ultrasound transducer46. In this manner, it will be known at what time ultrasound transducer46within the catheter50generates an ultrasound signal at the known frequency. The external ultrasound transducer48receives the ultrasound signal that was generated from the ultrasound transducer46of the catheter50and measures the time that the signal was received. The external ultrasound transducer48then sends a signal back to the processor20containing information regarding the time the ultrasound signal was received. Thus, the processor20, executing algorithms stored in the memory device21, processes the signal received from the external ultrasound transducer48to calculate the “time-of-flight” of the ultrasound generated by the ultrasound transducer46. Stated another way, using the known time stamp of the ultrasound signal generated by the ultrasound transducer46within the catheter50and the time stamp that the external ultrasound transducer48received the ultrasound signal that was generated by the ultrasound transducer46, the processor20can determine the transit time of the ultrasound signal between the ultrasound transducer46of the catheter50and the external ultrasound transducer48. Using the “time-of-flight” of the ultrasound signal generated by the ultrasound transducer46, along with the estimated known distance from the external ultrasound transducer48to the trachea92and/or esophagus91, the processor20then mathematically calculates a comparison between the time-of-flight or transit time to an estimated distance between the ultrasound transducer46of the catheter50and the external ultrasound transducer48.

Further, in one embodiment and referring toFIG.4, the catheter body160can have a plurality of markings112uniformly spaced along its external surface that can be used in conjunction with the ultrasound transducer46and external ultrasound transducer48to determine accurate placement of the catheter50. These markings112can function as placement markers which assist the user in assessing the depth that the catheter50is placed within the body78. For instance, when the ultrasound transducer46is located at the distal end60of the catheter50, the markings112can be present from the distal end60of the catheter50to a point126on the catheter50that spans a distance that can correspond with the average distance between the trachea92and nostril87in a typical patient. As the catheter50is being inserted into the body78via the nostril87, once the markings112are no longer visible outside the body78, the user can instruct the system2to initiate the ultrasound transducer46and/or external ultrasound transducer48and start monitoring the display device22to observe the ultrasound signal attenuation, ultrasound image, or other calculations derived from the ultrasound signals as described above or to start monitoring for a visual indication, auditory indication, or both that the catheter50has be inserted into the correct (e.g., digestive tract) or incorrect location (e.g., respiratory tract). In an alternative embodiment, these markings112can assist the user in measuring the flow or distribution of liquid to or from the patient.

Further, as an alternative or in addition to generating and/or detecting ultrasound signals via the ultrasound transducer46and/or the external ultrasound transducer48, the health care provider can also verify accurate placement of the catheter50in the esophagus91rather than the trachea92by observing for the presence or absence of a plurality of markings112uniformly spaced along the external surface of the catheter50. As described above, such markings112can be used in conjunction with the ultrasound transducer46and external ultrasound transducer48to determine accurate placement of the catheter50. These markings112can function as placement markers which assist the user in assessing the depth that the catheter50is placed within the body78. For instance, when the ultrasound transducer46is located at the distal end60of the catheter50, the markings112can be present from the distal end60of the catheter50to a point126on the catheter50that spans a distance that can correspond with the average distance between the trachea92and nostril87in a typical patient. As the catheter50is being inserted into the body78via the nostril87, once the markings112are no longer visible outside the body78, the health care provider can be alerted to start monitoring the display device22to observe the received ultrasound signal data and/or to start monitoring for a visual indication, auditory indication, or both that the catheter50has be inserted into the correct (e.g., digestive tract) or incorrect location (e.g., respiratory tract).

It should also be understood that multiple ultrasound transducers46and/or external ultrasound transducers48can be positioned at different spatial locations (i.e., multiple ultrasound transducers46placed along the length or around the circumference of the catheter50; multiple external ultrasound transducers48placed in a special distribution on the skin externally, etc.). Also contemplated is the possibility of utilizing different frequencies or frequency ranges for each of the multiple ultrasound transducers46or each of the external ultrasound transducers48, depending on which of the multiple ultrasound transducers (on the catheter or external) are transmitting the ultrasound waves. Specifically, when it comes to machine learning and pattern recognition, if the fidelity and certainty of data from one ultrasound transducer is not adequate, the machine learning algorithm's performance can be improved via the use of additional ultrasound transducers46and/or48.

For instance, such an arrangement can be useful, for instance, when the ultrasound transducers46are placed around the circumference of the catheter50, because at any given moment, one portion of the outer wall of the catheter50might stick to one wall of the esophagus91or trachea92, while other portions of the outer wall of the catheter50may be resting in air (i.e., if you are in trachea). In fact, the mere presence of ultrasound transmission via ultrasound transducers46placed around the circumference of the catheter50may be enough to allow for differentiation between the trachea and the esophagus. For instance, by utilizing multiple ultrasound transducers46spaced around the outer wall of the catheter, the processor could be able to differentiate between the presence of the catheter50in the esophagus91or the trachea92. This is because the outer wall of the catheter50would be exposed to air at least at some portions of its outer wall and to cartilage at some other portions of its outer wall in the trachea, which would result in different ultrasound frequency responses. Meanwhile, in the esophagus, the ultrasound transducers46would most likely only be exposed to muscle and tissue in the esophagus, where the frequency response would generally not change.

Regardless of the particular method by which proper placement of the catheter50is determined, once the distal end or tip60of the catheter50has been accurately placed within the desired location in the digestive tract, the health care provider can then optionally remove the ultrasound transducer46and/or external ultrasound transducer48, particularly when the ultrasound transducer46is located within the lumen70of the catheter and includes a wired connection, where the wire assembly62electrically connects the ultrasound transducer46to the processor20via the electrical connector or controller coupler36, while the position of the catheter50is maintained. The health care provider can then attach medicine and nutritional delivery tubes to the y-port connector44for introducing fluids into the body (e.g., digestive tract) for medical treatment. On the other hand, if the ultrasound transducer46is wireless, the ultrasound transducer46and external ultrasound transducer48can optionally be left in place, and the health care provider can then attach medicine and nutritional delivery tubes to the y-port connector44for introducing fluids into the body (e.g., digestive tract) for medical treatment.

Moreover, in conjunction with the ultrasound transducer46and external ultrasound transducer48described herein, the system2also contemplates the use of an optional signal generator58and associated transceiver32that can be used to track the position of the distal end60of the catheter50as it is being inserted into the patient's body78. In one embodiment, the signal generator58, which is located at the distal end60of the catheter and can be connected to the apparatus10via the controller coupler/electrical connected36and the wire assembly62(seeFIGS.1,3, and4), can be formed through one or a plurality of spirals or coils of wires. Further, the apparatus10can be configured to transmit electrical current through the wires such that the current travels in a circular path defined by the coils. This circular motion of current produces an electromagnetic field. In operation, when the apparatus10sends electrical current to the coils of the signal generator58, the coils then transmit a signal or electromagnetic field capable of being detected by the non-invasive transceiver32. The transceiver32then detects the electromagnetic field or signal generated by the signal generator58inside the patient's body78and the system2analyzes the resulting information to cause the display device22and the printer28to produce additional graphics37which can assist the health care provider in a catheter placement procedure in conjunction with ultrasound data acquired by the ultrasound transducer46and/or external ultrasound transducer48. For instance, the system2can include a memory device21including machine readable instructions and one or more computer programs (which, for example, may include a plurality of algorithms23) which are used by the processor20to process the signal data produced by the signal generator and transmitted by the transceiver32, after which the processed data is displayed in graphical format on the display device22corresponding to the location of the distal end60of the catheter50within the patient's body78. In one particular embodiment, the transceiver32can be used to determine the distance the signal generator58is from the transceiver32and its depth in the patient's body78can communicate with the display device22via the processor20to show a reference image of a non-subject body and an image of the signal generator58located on the display device22with the reference image.

FIG.7Ais a schematic view of the catheter guidance system2of the present invention as the system captures ultrasound data as the catheter50ofFIG.6Ais inserted into the esophagus91and other anatomical regions of the digestive tract in real-time via the ultrasound transducers46and48of the present invention. The processor20, memory device21, and algorithms23can be used to analyze the data received from the ultrasound transducers46and48to cause a graph37to be shown on the display device22, where the frequency and amplitude response are indicative of placement of the catheter50in the esophagus91. Specifically, the frequency vs. amplitude graph37shows a sharp increase in amplitude then a gradual attenuation in amplitude as the frequency increases. This type of frequency response with a trend of a gradually decreasing amplitude is indicative of the behavior of the ultrasound waves as the waves travel through muscle and tissue in the esophagus91.

FIG.7Bis a schematic view of the catheter guidance system2of the present invention as the system captures ultrasound data as the catheter50ofFIG.6Bis inserted into the trachea92and other anatomical regions of the respiratory tract in real-time via the ultrasound transducers46and48of the present invention. The processor20, memory device21, and algorithms23can be used to analyze the data received from the ultrasound transducers46and48to cause a graph37to be shown on the display device22, where the frequency and amplitude response are indicative of placement of the catheter50in the trachea92. Specifically, the frequency vs. amplitude graph37shows attenuation in amplitude from the harmonic frequency fθto the 3rd, 5th, 7th, 9thand 11thharmonic frequencies. This type of frequency response with a trend of a decreasing amplitude but with sharp spikes of increased frequencies at the harmonic frequencies is indicative of the behavior of the ultrasound waves as the waves travel through air between rings of the cartilaginous tissue of the trachea92.

It should also be appreciated that the tubing assembly, electronic catheter unit and catheter position guidance system of the present invention can be used in a variety of catheter procedures and applications. These procedures may involve the treatment of the digestive or gastrointestinal tract or other portions of the human body. Additionally, these procedures may involve the treatment of the respiratory tract of the human body, such as confirmation of tube location in an endotracheal tube insertion procedure. 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.

Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.