Patent Application
20220062574
The subject matter of the present invention relates generally to carbon dioxide and/or pressure sensing within a tube to verify the placement of the tube in a patient's airway or esophagus.
Physicians and other health care providers frequently use catheters to treat patients. Known catheters include a tube which is inserted into the human body. For instance, some catheters or tubes include endotracheal tubes for delivering mechanical ventilation to a patient's airway. Additionally, certain catheters are inserted through the patient's nose or mouth for treating the digestive or gastrointestinal tract. These catheters, sometimes referred to as enteral catheters, typically include feeding tubes. The feeding tube lies in the stomach or intestines, and a feeding bag delivers liquid nutrient, liquid medicine or a combination of the two to the patient.
When using these known catheters, it is important to place the end of the catheter at the proper location within the human body. However, the esophagus of the digestive tract and the trachea of the respiratory tract are blind to the health care provider during catheter placement. Erroneous placement of the catheter tip may injure or harm the patient. For example, if the health care provider erroneously places an enteral catheter into the patient's trachea, lungs, or other anatomical regions of the respiratory system rather than through the esophagus and to the stomach to reach the desired location in the digestive tract for delivering nutrients or medicine, liquid may be introduced into the lungs with harmful, and even fatal, consequences. In particular, the esophagus of the digestive tract and the trachea of the respiratory system are in close proximity to each other and are blind to the health care provider during catheter placement, which creates a dangerous risk for erroneous catheter placement.
In some cases, health care providers use X-ray machines to gather information about the location of the catheters within the body. There are several of disadvantages with using X-ray machines. For example, these machines are relatively large and heavy, consume a relatively large amount of energy and may expose the patient to a relatively high degree of radiation. Also, these machines are typically not readily accessible for use because, due to their size, they are usually installed in a special X-ray room. This room can be relatively far away from the patient's room. Therefore, health care providers can find it inconvenient to use these machines for their catheter procedures. In addition, using X-ray technology is expensive and is a time-consuming task that can create unnecessary delays in delivering critical nutrients to the patient.
Accordingly, there is a need to overcome each of these disadvantages.
Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
The present invention is directed to a catheter sensor assembly. The catheter sensor assembly includes a catheter having a proximal end and a distal end and extending in a longitudinal direction, wherein the proximal end and the distal end define a lumen therebetween, and wherein the catheter is configured for placement within a digestive tract or airway of a patient. The catheter sensor assembly also includes an aspiration device and a sensor, wherein the sensor comprises a carbon dioxide sensor, a pressure sensor, or a combination thereof.
In one particular embodiment of the catheter sensor assembly, the sensor can be located at the distal end of the catheter.
In another embodiment, the sensor can be located within the aspiration device.
In an additional embodiment, the sensor can be configured to provide carbon dioxide readings, pressure readings, or a combination thereof measured by the sensor from air in the lumen to a processor in real-time. Moreover, the sensor can be configured for a wired connection or a wireless connection to the processor.
In a further embodiment, the aspiration device can be configured to draw a small volume of air from the lumen of the catheter. Moreover, the aspiration device can be further configured to deliver a positive pressure of air through the lumen of the catheter to the distal end of the catheter. Further, the delivery of positive pressure of air to the distal end of the catheter can be configured to differentiate between placement of the distal end of the catheter in the esophagus and occlusion of the distal end of the catheter when the distal end of the catheter is placed in the airway.
In one more embodiment, the catheter sensor assembly can include a flow rate sensor.
The present invention is further directed to a catheter guidance system comprising: a processor; a power source; a display device, and a catheter sensor assembly. The catheter sensor assembly includes a catheter having a proximal end and a distal end and extending in a longitudinal direction, wherein the proximal end and the distal end define a lumen therebetween; an aspiration device; and a sensor, wherein the sensor comprises a carbon dioxide sensor, a pressure sensor, or a combination thereof. The sensor communicates with the processor via an electrical connection to deliver carbon dioxide readings, pressure readings, or a combination thereof measured by the sensor from air in the lumen to the processor in real-time. The display device is coupled to the processor and displays the carbon dioxide readings, pressure readings, or a combination thereof communicated by the sensor. A carbon dioxide reading profile, a pressure profile, or both a carbon dioxide reading profile and a pressure profile profile after a pre-determined amount of time as shown on the display device indicates placement of the catheter in a digestive tract or an airway of a patient.
In one particular embodiment of the catheter guidance system, the system can include a memory device storing instructions which, when executed by the processor, cause the processor to (i) interpret the carbon dioxide readings, the pressure readings, or a combination thereof communicated by the sensor and (ii) cause the display device to communicate whether the catheter is placed within the digestive tract of the patient or the airway of the patient based on the interpretation of the carbon dioxide readings, the pressure readings, or a combination thereof.
In another embodiment, the sensor can be located within the aspiration device.
In an additional embodiment, the catheter guidance system can further include at least one navigational guide configured to indicate when the distal end of the catheter has passed the epiglottis of the patient when the distal end of the catheter is inserted through the patient's nose or mouth. Moreover, the system can further include a memory device storing instructions which, when executed by the processor, cause the processor to (i) interpret the carbon dioxide readings, the pressure readings, catheter location readings from the at least one navigational guide, or a combination thereof communicated by the sensor and (ii) cause the display device to communicate whether the catheter is placed within the digestive tract of the patient or the airway of the patient based on the interpretation of the carbon dioxide readings, the pressure readings, the catheter location readings, or a combination thereof.
In yet another embodiment, the aspiration device can be configured to draw a small volume of air from the lumen of the catheter to deliver a positive pressure of air through the lumen of the catheter to the distal end of the catheter.
The present invention is further directed to a method for determining if a catheter is placed within a digestive tract or an airway of a body of a patient. The method include a step of inserting a distal end of a tubing assembly into an orifice of the body. The catheter sensor assembly includes: the catheter, wherein the catheter has a proximal end and a distal end and extends in a longitudinal direction, wherein the proximal end and the distal end define a lumen therebetween; an aspiration device; and a sensor, wherein the sensor comprises a carbon dioxide sensor, a pressure sensor, a flow sensor, or a combination thereof. The method further includes a step of activating the sensor, wherein the sensor measures carbon dioxide, pressure, or a combination thereof from air in the lumen and communicates with the processor via the wired connection or the wireless connection to deliver carbon dioxide readings, pressure readings, or a combination thereof to the processor in real-time, wherein a display device is coupled to the processor and displays the carbon dioxide readings, pressure readings, or a combination thereof communicated by the sensor. The method further includes steps of advancing the distal end of the catheter inside the body in a direction away from the orifice while the sensor is activated; and observing the carbon dioxide readings, pressure readings, flow readings, or a combination thereof on the display device, wherein a carbon dioxide reading profile, a pressure reading profile, a flow reading profile, or a combination of a carbon dioxide reading profile, a pressure reading profile and/or a flow reading profile after a pre-determined amount of time indicates placement of the catheter in a digestive tract or an airway of a patient.
In one particular embodiment of the method, a memory device stores instructions which, when executed by the processor, cause the processor to (i) interpret the carbon dioxide readings, the pressure readings, or a combination thereof communicated by the sensor and (ii) cause the display device to communicate whether or not the catheter is placed within the digestive tract of the patient based on the interpretation of the carbon dioxide readings, the pressure readings, the flow readings, or a combination thereof.
In one embodiment, the orifice can be a nose or a mouth.
In another embodiment, the sensor can be located within the aspiration device.
In a further embodiment, suction from the aspiration device can direct air sampled from a distal end of the catheter to the sensor. Moreover, the aspiration device can deliver at least one puff of positive air pressure to the distal end of the catheter then resumes suction of air from the distal end of the catheter to determine if the distal end of the catheter is located within the esophagus or if the distal end of the catheter is located within the airway and occluded.
In an additional embodiment, the method can include a step of delivering a positive pressure of air from the aspiration device through the distal end of the catheter while inserting the distal end of the catheter inside the body in a direction away from the orifice until the distal end of the catheter reaches a predetermined anatomical reference point. Moreover, steps (b) and (c) can be performed after the distal end of the catheter reaches the predetermined anatomical reference point.
In yet another embodiment, the method can include a step of: providing at least one navigational guide, wherein information from the at least one navigational guide is configured to indicate placement of the catheter in a digestive tract or an airway of a patient. Moreover, a memory device stores instructions which, when executed by the processor, cause the processor to (i) interpret the carbon dioxide readings, the pressure readings, the information from the at least one navigational guide, or a combination thereof and (ii) cause the display device to communicate whether or not the catheter is placed within the digestive tract of the patient based on the interpretation of the carbon dioxide readings, the pressure readings, the flow readings, the information from the navigational guide or a combination thereof.
These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
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 is configured for placement within a digestive tract or an airway of a patient. The tubing assembly also includes a sensor, where the sensor includes a carbon dioxide sensor, a pressure sensor, a flow sensor, or a combination thereof. The sensor can be located within the lumen of the catheter or in an air sampling chamber connected to the catheter. The sensor can communicate with a processor to deliver carbon dioxide and/or pressure readings to a display device. A catheter guidance system and a method for accurately placing a catheter in the digestive 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 continuous sampling of air during an intubation procedure of a patient, independently of inspiration or expiration of the patient, where the real-time carbon dioxide and/or pressure readings measured by the sensor can be used to determine if the distal end of the catheter is placed within the digestive tract (e.g., esophagus, stomach, intestines, etc.) or within the respiratory system (e.g., trachea, bronchi, lungs, etc.), in order to prevent improper placement that could be harmful and even fatal to a patient. Further, the present inventors have found that because the sensor 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 correct 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 the real-time monitoring of the carbon dioxide and the pressure and/or flow of the air inside or within a catheter to be placed in a predetermined location along the digestive tract (e.g., esophagus, stomach, intestines, etc.) or respiratory tract (e.g., trachea), which is facilitated by the sensor assembly of the catheter guidance system of the present invention, allows for the efficient and accurate placement of the catheter within the intended portion of the patient's anatomy at a low cost. For instance, the sensor in communication with the tubing assembly can monitor the carbon dioxide level and/or pressure and/or flow of air within the catheter as it is being directed by a health care provider in to the body of a patient, where the carbon dioxide, pressure and/or flow data can be transmitted to a display device via a processor. The health care provider can then view the carbon dioxide, pressure and/or flow data to determine if the catheter has been accurately placed, e.g., in the digestive tract, or erroneously placed, e.g., 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 sensor, 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 accurately placed, e.g., in the digestive tract, or erroneously placed, e.g., within 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 in
As best illustrated in
Health care providers can use the system 2 in a variety of catheter applications. In one example illustrated in
Referring to
As best illustrated in
In one embodiment, the tubular insulator 40 includes a tube having a proximal end attachable to an attachment member or neck of a controller coupler or electrical connector 36 and a distal end receivable by the union device; and an internal diameter which is substantially equal to or greater than an external diameter of a wire assembly 62 described below, which can serve as the hard wired electrical connection between the sensor 46 and the processor 20, so as to slide over the wire assembly 62. In another embodiment, the tubular insulator 40 may fit relatively tightly over the wire assembly 62 so as to be secured to the wire assembly 62.
In one embodiment best shown in
As illustrated in
As also shown in
The tubular connector 40, y-port connector 44, catheter 50, and tip 60 can be made from any suitable polymer or plastic material including, but not limited to, polyamide, polyethylene, polypropylene, polyurethane, silicone and polyacrylonitrile.
Referring still to
Turning now to the specifics of the sensor 46 and referring to
When the sensor 46 is disposed within the lumen 70 of the catheter 50, the sensor 46 can be surrounded by a filter formed from a porous filter material or porous filter media in order to prevent moisture from the opening 180 in the tip 60 of the catheter 50 from contacting the sensor 46 and affecting its carbon dioxide and/or pressure or flow readings. For instance, the filter can prevent water or other fluid ingress that may enter through the opening 180 from contacting the sensor 46, while still allowing air to penetrate into the lumen 70. In any event, the filter 64 is positioned within the tubing assembly 14 to protect the sensor 46 from water or other fluid ingress that may damage the sensor 46 of affect the accuracy of its carbon dioxide, pressure and/or flow readings.
Turning now to the makeup of the filter, the filter contemplated by the present invention can allow gases but not liquids to pass therethrough. Stated alternately, the filter of the present invention can be vapor permeable and liquid impermeable. The filter may comprise any suitable material or combination thereof. Exemplary suitable materials for the filter include but are not limited to reticulated polymer foams, expanded polymers (such as Porex® expanded polymers available from Porex Corporation, having offices in Fairburn, Ga.), expanded PTFE (such as Gore-Tex® expanded PTFE available from W.L. Gore & Associates, Inc., having offices in Newark, Del.), and porous metals (or powdered metals). As will be appreciated, the rate at which the gases are allowed to pass through the filter is not critical so long as it is sufficient to allow for a sufficient volume of air to come into contact with the sensor 46 to obtain accurate carbon dioxide, pressure and/or flow readings. It will also be appreciated that air flow rate may be affected or controlled in part by the composition of the filter. Nevertheless, in most embodiments, it is generally desirable for the insert to be able to allow at least 3 liters to 5 liters of gas to pass therethrough per hour. For use with a pediatric catheter, it may be desirable for the filter in an appropriately sized adapter to be able to allow at least 1 liter to 2 liters of gas to pass therethrough per hour. Further, it will be appreciated that the filter 64 may be hydrophobic or hydrophilic, although it is desired that the insert or insert media be generally hydrophobic. Where the filter is or contains a hydrophobic filter media or where the filter media is at least in part hydrophobically treated, the filter media may have larger pore sizes and therefore a higher flow rate therethrough (as compared to a hydrophilic or hydrophilically treated media) as the filter will be less likely to absorb liquids, become saturated and allow liquid to pass therethrough.
As shown in
Additionally, although any suitable sensor(s) 46, 56 for measuring carbon dioxide and pressure and/or air flow that can withstand the environmental conditions of the body can be used in the catheter guidance system 2, the sensor(s) 46, 56 can be in the form of a flip chip package having a small footprint such that it can be placed within the housing 200 of the aspiration device 52, lumen of the catheter 50, or any other suitable location within the tubing assembly 14. For instance, the sensor(s) 46, 56 can include a digital carbon dioxide sensor and a digital pressure and/or volumetric air flow sensor that includes analog and digital signal processing, an A/D converter, calibration data memory, and a digital communication interface for communication with the processor 20, all of which combine to allow for real-time, continuous, and highly accurate carbon dioxide and pressure and/or air flow sensing.
For instance, the carbon dioxide sensor can be an infrared carbon dioxide sensor or any other suitable type of capnograph or carbon dioxide sensor. The sensor(s) 46, 56 can include an MEMS component 48 having one or more MEMS active and passive components that form a non-dispersive infrared (IR) sensor. Carbon dioxide (CO2) strongly absorbs infrared radiation at a wavelength of 4.3 μm. Further, the carbon dioxide concentration at the end of a person's exhaled breath is approximately 5% to 6% of the exhaled air, which corresponds to about 35 mmHg to about 45 mmHg. Therefore, the MEMS infrared sensor is configured to detect carbon dioxide to determine whether the catheter 50 is being placed in the patient's airway and may be referred to as a MEMS infrared carbon dioxide sensor 48. More particularly, the MEMS component 48 includes an IR emitter 48a and an IR receiver 48b, which form the MEMS infrared carbon dioxide sensor 48. The IR emitter 48a emits infrared radiation, and the IR receiver 48b receives any reflected radiation. An IR path length between the IR emitter 48a and the IR receiver 48b dictates the carbon dioxide concentration the IR carbon dioxide sensor 48 can detect. Thus, the MEMS component 48, particularly the IR emitter 48a and IR receiver 48b, should be constructed such that the sensor can detect a carbon dioxide concentration of at least 30 mmHg to 50 mmHg and, in particular embodiments, of at least 35 mmHg to 45 mmHg. The IR carbon dioxide sensor can be disposed within the catheter 50 or the aspiration device 52.
The carbon dioxide sensor may generate an electrical signal corresponding to the level of carbon dioxide sensed by the sensor(s) 46, 56, and the voltage level of the signal varies based upon the level of carbon dioxide sensed by the sensor 46. In addition, the sensor(s) 46, 56 can also have a low operation voltage of less than 2.5 volts, such as from about 0.5 volts to about 2 volts, such as from about 1 volt to about 1.9 volts, such as about 1.8 volts, which allows for low power consumption, which can allow for the sensor(s) 46, 56 to be suitable for applications where the electrical connection between the sensor(s) 46, 56 and the processor 20 is wireless as opposed to a wired connection via the wire assembly 62, although a wired connection between the sensor 46 and the process 20 via the electrical connector or controller coupler 36 is still possible.
The carbon dioxide (CO2) concentration at the end of a person's exhaled breath is approximately 5% to 6% of the exhaled air, which corresponds to about 35 mmHg to about 45 mmHg. The sensor(s) 46, 56 determines the carbon dioxide concentration of the air within the air from the lumen 70, such as the air drawn into the catheter 50. In some embodiments, if the carbon dioxide concentration is at least 30 mmHg, the system 2 may determine that the tip 60 of the catheter 50 is placed in the patient's airway. In other embodiments, the system 2 may determine that the tip 60 of the catheter 50 is being placed in the patient's airway if the carbon dioxide concentration is at least 35 mmHg. That is, sensor(s) 46, 56 can be configured to sense a carbon dioxide concentration of at least 30 mmHg, or in other embodiments, of at least 35 mmHg, which corresponds to the low end of the typical range of carbon dioxide concentration in a person's exhaled breath. When the sensor(s) 46, 56 senses such a carbon dioxide concentration, the sensor(s) 46, 56 may provide feedback of the carbon dioxide concentration to the user via the display 22. In some embodiments, the feedback from the sensor(s) 46, 56 indicates the tip 60 is entering the airway when the carbon dioxide concentration sensed by the sensor 46 is 30 mmHg or 35 mmHg. In other embodiments, if the carbon dioxide concentration continues to rise past 30-35 mmHg as the catheter 50 is advanced into the patient, as shown on the display 22, the user may determine that the catheter 50 is being incorrectly placed in the patient's airway because the rising carbon dioxide concentration likely corresponds to the patient's respirations conveyed through the patient's airway. Stated differently, using the carbon dioxide level or concentration that is detected by the sensor(s) 46, 56, the user can determine whether the distal tip 60 of the catheter 50 resides in the patient's airway.
The pressure readings of the sensor(s) 46, 56 as the catheter 50 is inserted into either the digestive tract, e.g., esophagus, or the respiratory tract, e.g., trachea, may be used to determine placement of the catheter 50 based on anatomical differences between the esophagus and the trachea. For example, the esophagus contains no significant structure support and readily collapses when negative pressure is applied. Conversely, the trachea is lined with semi-rigid cartilage that maintains patency in the airway, even under moderate negative pressure. Thus, applying a negative pressure through a tube or catheter, including through the inner lumen of the nasogastric/nasojejunal tube, during placement can differentiate the location of the catheter or tube's tip based on this anatomical difference.
The aspiration device 52 can additionally be used to deliver a positive pressure of air through tip 60 of the catheter 50. For instance, during insertion of the catheter 50 into the patient's body 78, the aspiration device 52 can deliver a positive pressure of air through the tip 60 of the catheter in order to prevent any liquid, mucus, food particles, or other secretions from entering and/or clogging the tip 60 of the catheter 50. Additionally or alternatively, as will be described in more detail below, the aspiration device 52 can deliver one or more puffs of positive air pressure to assist with differentiating between placement of the catheter 50 in the digestive tract as compared to the respiratory tract, and to assist with determining whether the tip 60 of the catheter 50 is occluded. Moreover, the aspiration device 52 can be used to deliver positive pressure of air through the tip 60 of the catheter 50 to assist with insertion of the catheter 50 into the patient's body 78, such as insertion into the small intestine.
In some aspects of the invention, the catheter guidance system 2 can include a navigational guide for determining the depth of placement of the tip 60 of the catheter 50 within the patient's body. For instance, in one embodiment and referring to
Additionally or alternatively, the catheter guidance system 2 can be used with an electromagnetic catheter position guidance system (not shown) that can function as a navigational guide. The electromagnetic catheter position guidance system may include one or more electromagnetic transmitter(s) and/or receiver(s) positioned at the tip 60 of the catheter 50, wherein the transmitter(s) or receiver(s) at the tip 60 of the catheter 50 are in operative communication with a corresponding electromagnetic transmitter and/or receiver disposed external to the patient's body. The electromagnetic catheter position guidance system may track the positioning and placement of the tip 60 of the catheter 50 in real-time, e.g., tracing a path of placement of the tip 60 or measuring a distance traversed within the patient's body. Thus, the electromagnetic catheter position guidance system may provide a complementary method for a user to determine when the tip 60 of the catheter 50 has passed the epiglottis 87 of the patient and indicate that the sensor(s) 46, 56 should begin to sense the carbon dioxide and/or pressure levels by sampling air from the lumen 70 of the catheter 50. The electromagnetic position guidance system may be used in conjunction with the markings 112, on its own, or in conjunction with any other suitable method for determining the depth of insertion of the tip 60 of the catheter 50 within the patient's anatomy.
Now that the specific components of the catheter guidance system 2 have been discussed in detail, a method of using the catheter guidance system 2 of the present invention in order to verify the accurate placement of a catheter 50 used for enteral feeding in the digestive tract is discussed in more detail below with reference to
Generally, the method for determining if the catheter 50 is accurately placed within a digestive tract of a body 78 of a patient includes inserting a distal end of the tubing assembly 14 (e.g., the distal end or tip 60 of the catheter 50) into an orifice 72 of the body 78, such as a nostril 87 of the patient's nose. As described above, the tubing assembly 14 can include the catheter 50 and at least one sensor, either in the form of the one or more sensor(s) 56 of the aspiration device 52 or the sensor 46 within the catheter 50. Once the tubing assembly 14 is inserted into the orifice 72 of the body 78, the sensors 46, 56 can be electrically connected to a processor 20 via a wired connection, although a wireless connection is also contemplated by the present invention such that no wire assembly or controller coupler is required.
In one aspect, the aspiration device 52 may deliver a positive pressure of air flow through the catheter 50 when the distal end 60 of the catheter 50 is inserted. The positive pressure of air may be delivered until the user determines that the distal end 60 of the catheter 50 has passed the epiglottis 90 of the patient. For instance, when the markings 112 are no longer visible to the user, the user may interpret that the distal end 60 of the catheter 50 has likely passed the epiglottis 90 of the patient. Notably, the epiglottis 90 is the point at which the respiratory tract, e.g., trachea 92, diverges from the digestive tract, e.g., esophagus 91. By delivering a positive pressure of air through the distal tip 60 of the catheter 50 until the distal tip 60 has passed the epiglottis 90, the likelihood that water, fluid, mucus or other substances that may be present within the patient's nostril 87 or nasopharynx 89 will be aspirated or sucked into the catheter 50 is significantly reduced. Moreover, the sensing by the sensor(s) 46, 56 need not be initiated until after the distal tip 60 passes the epiglottis 90, at which point the sensing can be used to differentiate between the positioning of the distal tip 60 in the digestive tract or the respiratory tract.
Next, the sensor(s) 46, 56 are activated, and the sensor(s) 46, 56 then begin to continuously measure the carbon dioxide concentration, the pressure and/or airflow or a combination thereof from air in the lumen 70 of the catheter. The aspiration device 52 may be switched to a vacuum suction or negative pressure mode to pull a small amount of air from the lumen 70. The vacuum suction or negative pressure can be continuous or intermittent, which may be important for preventing hypoxia in pediatric or neonatal patients. For instance, the aspiration device 52 may pull about 0.15 mL/sec to about 0.40 mL/sec of air from the lumen 70 of the catheter 50 in order to draw air past the sensors 56, e.g., carbon dioxide sensor 220, pressure sensor 230 and/or flow sensor 240. The sensors 220, 230, 240 communicate with the processor 260 of the aspiration device 52 to deliver carbon dioxide readings, pressure readings, flow readings, or a combination thereof to the processor 260 in real-time, and the processor 260 may be further coupled to communicate with the processor 20. In an embodiment in which a sensor 46 is present within the catheter 50, the sensor 46 communicates with the processor 20 via the wired connection (e.g., wire assembly 62) or the wireless connection to deliver carbon dioxide readings, pressure readings, flow readings, or a combination thereof to the processor 20 in real-time.
In addition, a display device 22 is coupled to the processor 20 and displays the carbon dioxide readings, pressure readings, flow readings or a combination thereof communicated by the sensor(s) 46, 56 for a health care provider to use during the catheter insertion procedure. For instance, as the distal end or tip 60 of the catheter 50 is advanced inside the body 78 in a direction away from the orifice 72 while the sensor(s) 46 and/or 56 are activated, the carbon dioxide readings, pressure readings, or a combination thereof are observed or monitored on the display device 22.
Specifically, a generally constant, low concentration carbon dioxide profile, a generally constant or decreasing negative pressure profile, or both a combination thereof displayed or otherwise communicated by the display device 22 after a pre-determined amount of time indicates placement of the catheter 50 in a digestive tract (e.g., esophagus 91, stomach 74, intestine 96, or other anatomical region of the digestive tract of a patient. On the other hand, a non-constant or variable (e.g., sinusoidal wave, square wave, etc.) carbon dioxide profile displayed or otherwise communicated by the display device 22 after a pre-determined amount of time indicates placement of the catheter 50 in the respiratory system (e.g., trachea 92, bronchi 93, lungs 94, or other anatomical region of the digestive tract of the patient). If the procedure is, e.g., insertion of a feeding tube intended for placement in the digestive tract, then at the time of detection of catheter placement in the respiratory tract the insertion procedure should be stopped immediately and the tubing assembly 14 be removed from the respiratory tract to avoid potential harm to the patient. Further, in order for such information to be displayed or otherwise communicated by the display device 22, a memory device 21 stores instructions which, when executed by the processor 20, cause the processor 20 to (i) interpret the carbon dioxide readings, the pressure readings, or a combination thereof communicated by the sensor(s) 46 and/or 56 and (ii) cause the display device 22 to communicate whether or not the catheter 50 is placed within the digestive tract of the patient based on the interpretation of the carbon dioxide readings, the pressure readings, or a combination thereof.
The present inventors have found that the distinctions between the carbon dioxide and/or pressure profiles of air sampled from the lumen 70 of the catheter, either via placement of the sensor(s) 56 in the aspiration device 52 upstream, where the air sampled is obtained from the lumen 70 via suction from a vacuum pump 58, or placement of the sensor 46 in the lumen 70 of the catheter 50 itself, when the distal end or tip 60 of the catheter 50 is placed within the digestive tract or respiratory system allow for an efficient and possibly life-saving determination of accurate enteral feeding catheter 50 placement in the digestive tract, where erroneously placing the catheter in the respiratory system would deliver fluid into the lungs or damage lung tissue, which can have fatal consequences.
The aspiration device 52 is configured to generate a low level of vacuum suction that is continuously pulled through the catheter 50. As the catheter 50 is advanced through the body, pressure readings detected by the sensor(s) 46 and/or 56 change based on the vacuum resistance (i.e., negative pressure) sensed at the distal end 60 of the catheter 50. For example, when the distal end 60 of the catheter 50 is in free airspace, such as the trachea, the vacuum (negative) pressure signal will be low. Whereas, if the distal end 60 of the catheter 50 is in contact with tissue, e.g. in the esophagus, the vacuum (negative) pressure signal will be higher. The display device 22 may provide information regarding the location of the distal end 60 of the catheter 50, such as in the form of a graph 37 (see
Moreover, the aspiration device 52 can be implemented to confirm whether a detected vacuum resistance within the catheter 50 is due to placement of the catheter 50 within the esophagus 91 or due to occlusion (e.g., debris such as food particulate, mucus, fluid, etc.) of the distal tip 60 of the catheter 50. For instance, the aspiration device 52 can be used to deliver one or more “puffs” or bursts of positive air pressure followed by immediately resuming suction through the catheter 50. If vacuum resistance is immediately obtained following the puff or burst of positive air pressure, then the user can infer that the catheter 50 is placed within the esophagus 91. However, if vacuum resistance is not immediately obtained following a puff or burst of positive air pressure, then the catheter 50 may be in the airway and the sensor 46 may continue to look for airway signals such as elevated carbon dioxide levels and/or free flow of air through the catheter 50.
Additionally, a flow sensor can be incorporated into the sensor(s) 46 and/or 56. A free flow of air within the catheter 50 may indicate placement of the catheter 50 within the airway of a patient, particularly when coupled with an elevated level of carbon dioxide.
For instance, as shown in
On the other hand, as shown in
Further, as an alternative or in addition to monitoring the carbon dioxide and/or pressure readings as determined by the sensor(s) 46 and/or 56 over time and observing the change from non-constant or oscillating readings to constant readings, the health care provider can also verify accurate placement of the catheter 50 in the esophagus 91 rather than the trachea 92 by observing for the presence or absence of a plurality of markings 112 uniformly spaced along the external surface of the catheter. As described above, such markings 112 can be used in conjunction with the sensor 46 to determine accurate placement of the catheter 50. These markings 112 can function as placement markers which assist the user in assessing the depth that the catheter 50 is placed within the body 78. For instance, the markings 112 can be present from the distal end 60 of the catheter 50 to a point 126 on the catheter 50 that spans a distance that can correspond with the average distance between the trachea 92 and nostril 87 in a typical patient. As the catheter 50 is being inserted into the body 78 via the nostril 87, once the markings 112 are no longer visible outside the body 78, the health care provider can initiate sensing of the carbon dioxide and/or pressure levels. If the carbon dioxide and/or pressure readings are still oscillating to the analog of breathing once the markings 112 are no longer visible outside the body 78, then the health care provider will know that the catheter 50 has been improperly inserted into the trachea 92 instead of the esophagus 91, and the catheter 50 can be immediately retracted.
Notably, the catheter guidance system 2 of the present invention may be further used to guide and determine the correct placement of an enteral feeding tube even when a patient is intubated with an endotracheal tube for mechanical ventilation. In such instances, the sensor(s) 46 and/or 56 may not be activated until the distal tip 60 of the catheter 50 has extended a distance into the patient's body that is determined to be roughly equal to or longer than the distance from the nostril 87 to the trachea 92, as there would be little to no breathing pattern of inspiration or expiration above the point at which a cuff of the endotracheal tube is placed within the trachea 92.
Regardless of the particular method by which proper placement of the catheter 50 is determined, once the distal end or tip 60 of the catheter 50 has been accurately placed within the desired location in the digestive tract, the health care provider can then optionally remove or disconnect the sensor 46, while the position of the catheter 50 is maintained. The health care provider can then attach medicine and nutritional delivery tubes to the y-port connector 44 for introducing fluids into the body (e.g., digestive tract) for medical treatment. On the other hand, if the sensor 46 is wireless, the sensor 46 can optionally be left in place, and the health care provider can then attach medicine and nutritional delivery tubes to the y-port connector 44 for introducing fluids into the body (e.g., digestive tract) for medical treatment.
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, such as the correct positioning of an endotracheal tube. 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.
