Patent Application
20240245583
The present invention relates to feeding tube placement/monitoring, as well as the measuring of gastric volume, gastric emptying, and detection and management of gastric reflux and the management of patient care.
All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each such individual publication or patent application were specifically and individually indicated to be so incorporated by reference.
Enteral feeding through a feeding tube allows patients to receive nutrition when he/she cannot receive nutrition through the mouth, cannot swallow safely or to provide supplemental nutrition.
Placing a gastric tube (naso- or oro-gastric, herein also referred to as NG tube, or feeding tube) also has its challenges. An NG tube may be inadvertently placed in the trachea rather than the esophagus, resulting in complications or even death. A solution is also needed to accurately place the NG tube in the gastrointestinal tract (i.e., the esophagus, stomach or intestines), and not in the trachea or the lungs.
Tracking the feeding status of the patient is also important, so that the patient is not underfed or overfed. Note that the term “GRV” used herein may refer to Gastric Residual Volume or gastric emptying or gastric residual feed or gastric motility or gastric status.
Preventing, identifying, and managing gastric reflux is also important during enteral feeding, as reflux can be introduced into the lungs, causing serious medical complications.
Embodiments of a gastric access device are disclosed herein which improve the ability to confidently access the GI tract and avoid inadvertent entry into the trachea/lungs of a patient. Embodiments include one or more sensor types to determine whether the device is in the GI tract or the trachea/lungs. Some sensor types positively ID the GI tract, such as impedance/conductivity sensors, pH sensors, ECG (electrocardiogramsors, pressure sensors etc. Some sensor types positively ID the trachea/lungs such as temperature sensors, humidity sensors, O2 sensors, CO2 sensors, flow sensors, acoustic sensors, pressure sensors etc. Some of these sensors may ID both. A combination of sensors, at least one of which positively IDs the GI tract, and at least one of which positively IDs the trachea/lungs, may be used to properly locate the device in the GI tract (or the trachea/lungs). Alternatively, 2 different sensor types which positively ID the GI tract may be used to properly locate the device. Alternatively, 2 different sensor types which positively ID the trachea/lungs may be used to properly locate the device.
In some embodiments, only one sensor type is needed to properly locate the device. In some embodiments, 2 sensor types are available to properly locate the device. In some embodiments, 3 sensor types are available to properly locate the device. All sensor types available may not be used on every patient in every environment.
One or more of any sensor type may be used along the length of the gastric access device. In some embodiments, more than one sensor is placed on or along the gastric access device so that at least one sensor will be in a functional location. For example, more than one temperature sensor may be along the gastric access device so that at least one temperature sensor will be in a position to measure surrounding fluid and not be up against tissue as the device is advanced. For example, more than one temperature sensor may be arranged at more than one location circumferentially around the device. Alternatively or additionally, more than one temperature sensor may be arranged at more than one location along the length of the device.
The monitor/controller of the device may analyze the signals for the one or more types of sensors to determine the location of the device. Some signal types may provide more confidence than others and may override others. Some signal types may take longer to analyze and may serve as confirming or non-confirming signals to a previous signal. The monitor may receive signals from the sensors on a continual, intermittent, or on demand basis. Some signal types may be received and analyzed essentially in real time, while some signal types may take longer to receive and analyze.
Some embodiments of the gastric access device include the ability to monitor gastric residual volume or gastric emptying. Some embodiments include the ability to control the feed rate and/or amount based on the gastric residual volume or gastric emptying.
Some embodiments of the gastric access device include preventing, identifying and/or managing gastric reflux.
In some embodiments, the sensor types may be used for monitoring the patient also. For example, temperature sensors may be used to both locate the device, and also monitor patient temperature once the device is in place. Impedance/conductivity sensors may be used for determining device location, reflux identification, and/or monitoring gastric residual volume or gastric emptying over time after the device is placed. ECG sensors may be used for placement and also to monitor the patient's ECG after the device is placed. ECG sensors, impedance/conductivity sensors, and/or other sensors may use the same, or different, electrodes.
One variation of a feeding system may generally comprise a gastric access device having a length, one or more sensors positioned along the length, and a controller in communication with the one or more sensors, wherein the controller is configured to receive a signal from the one or more sensors relating to a parameter of a fluid within a stomach of a subject. The controller may be further configured to determine a gastric residual volume (GRV) based upon the signal and control a rate of a feed or formula introduced into the stomach such that the GRV is maintained at a steady level.
One variation of a method of managing delivery of feed or formula into a stomach of a subject may generally comprise contacting a fluid within a stomach of a subject via one or more sensors positioned along a length of a gastric access device, receiving a signal from the one or more sensors into a controller in communication with the one or more sensors, wherein the signal relates to a parameter of the fluid, determining a gastric residual volume (GRV) based upon the signal, and controlling a rate of a feed or formula introduced into the stomach such that the GRV is maintained at a steady level.
Various exemplary embodiments are described in detail with reference to the following figures, wherein:
For convenience of explanation, exemplary embodiments are described below with reference to the figures in the context of placing feeding tubes, assessing gastric residual volume/emptying, and preventing/identifying/managing/monitoring gastric reflux in patients.
In
The sensors may be used to help with device placement or may be used to assess gastric emptying/contents, or preventing, identifying and/or managing reflux, or may be used for any two or more of these purposes. For example, some embodiments of the gastric access device includes at least one impedance sensor to measure impedance of the environment around the sensor and at least one temperature sensor. The impedance sensor(s) may be used for device placement and/or gastric emptying monitoring and/or reflux, while the temperature sensor(s) may be used for device placement, and possibly for ongoing patient temperature monitoring.
One or more temperature sensors may be used for device placement by sensing the relatively small temperature fluctuations caused by breathing ambient air that is at a temperature different than that of the body. For example, room temperature air is normally below the temperature of the body. If the gastric access device is advanced into the trachea by mistake, instead of into the esophagus, the temperature sensor(s) on the gastric access device will detect the temperature fluctuations associated with breathing. These temperature fluctuations are not present when the gastric access device is property placed in the gastric system, i.e., in the esophagus, stomach or intestines.
A temperature sensor on the gastric access device transfers a temperature signal from the sensor to a controller via leads in the gastric access device. This temperature signal will show fluctuations associated with breathing when the gastric access device is incorrectly placed in the trachea or the lungs. This is important because this is a dangerous mistake and can cause complications and even death if feed is subsequently introduced into the lungs by mistake.
The embodiment in
To confirm that the gastric access device is positioned in the stomach and not the lungs or trachea, a secondary sensing system may be utilized. For example, one or more temperature sensors may be used on the gastric access device to sense temperature fluctuations, or the lack of temperature fluctuations, caused by breathing. If temperature fluctuations associated with breathing are detected, it is likely the device is in the trachea or the lungs and should be retracted. If no temperature fluctuations associated with breathing are detected, and the impedance sensor(s) show high conductivity/low impedance, the device is likely in the stomach. Temperature fluctuations associated with breathing will likely have a frequency associated with breathing, for example:
The controller may incorporate a frequency filter to filter for these or other breathing frequencies to isolate temperature fluctuations associated with breathing from the temperature signal over time.
These frequencies can be used by the controller/monitor to determine that temperature fluctuations are or are not associated with breathing. This signal may need to be analyzed across more than one breath and as a result, may take longer for the controller to analyze than the impedance/conductance signal. The determination of whether the temperature signal represents breaths may take 8-15 or 10-20 seconds. As a result, the temperature readings may be used as a secondary indicator of device placement—a confirmation of the impedance sensor indication of placement. The user may be prompted by the device to pause advancement of the device while this confirmation is taking place.
In some embodiments, temperature sensors are used to sense temperature at the point when and where the device first enters the body. The temperature sensors may sense temperature fluctuations due to breathing in the throat of the patient as the device is inserted. These fluctuations may stop as the device passes the junction between the trachea and the esophagus. As this is a relatively short distance into the patient (i.e. around 5-15 cm), the flattening of temperature fluctuations at this distance may be an indicator that the device is properly propagating down the esophagus vs. the trachea. This temperature fluctuation flattening or disappearance at this relatively short distance into the patient is a further indicator that the device is being correctly placed. Alternatively, the lack of flattening of temperature fluctuations, or the increase in magnitude of temperature fluctuations as the device is advanced is an indication that the device is being advanced into the trachea. The distance beyond the lips that the device has been advanced may be automatically determined by the system by utilizing dimensional markings, or landmarks, along the length of the shaft of the device and a camera, or other detection mechanism, at the lips/device entry point.
In some embodiments, one or more temperature sensors on the feeding tube may sense ambient temperature before the tube is inserted into the patient. In some embodiments, ambient temperature may be continuously or intermittently measured over time using a temperature sensor outside of the patient, such as an ambient temperature sensor incorporated into the controller, or an ambient temperature sensor at the proximal end of the feeding tube which remains outside of the patient. An ambient temperature sensor may also be apart from both the feeding tube and the controller, but in communication with the controller. Ambient temperature may be used to determine the relative temperature of the patient at different locations within the anatomy, by comparing the temperature sensed by the sensors on the feeding tube to ambient temperature. In this way, relative temperature can be measured at different locations along the feeding tube, and within the anatomy. Also, an average temperature may be used by looking at a dampened, temperature signal. An average, or dampened, temperature signal may not show the same fluctuations of temperature in the lungs, or lack of fluctuations of temperature in the espohogus, but the average temperature in the lungs will be lower than that in the espohogus, if the ambient temperature is below body temperature. By monitoring the average/dampened temperature, at one point, at two points, or along the feeding tube, as the device is advanced, the controller can determine approximately where in the anatomy the device is. Different signals at different locations along the length of the feeding tube will provide temperature information (either average temperatures or temperature fluctuations) that can indicate if that segment of the feeding tube is in the pharynx, trachea, esophagus, lung, stomach, intestines or up against tissue. Other sensors, such as impedance/conductivity sensors, may be used to help identify the location. For example, if the temperature sensors are measuring body temperature and no fluctuations in temperature, the portion of the feeding tube with these sensors may be in the stomach, or may be up against tissue. Conductivity/impedance sensors may be able to differentiate between the two. ECG may also be used, or pH, or other sensor types.
If the controller receives signals from the temperature sensors showing temperature fluctuations associated with breathing, where the temperature sensor is past the RGJ (Respiratory-Gastric Junction), as shown in box 714, the controller will indicate to the user that the device is likely in the trachea or lungs and instruct the user to retract the device, as shown in box 716.
If, during device advancement, the sensors first sense high conductivity, as shown in box 704, it is possible the gastric access device is in the stomach, and the sensors are sensing stomach contents. The controller may indicate that the device is in the stomach, or the controller may ask the user to pause for a few seconds, by displaying or playing a pause signal, so that it can gather temperature sensor signal data to determine whether there are fluctuations associated with breathing detected by the temperature sensors. If these fluctuations are detected, where the temperature sensor is past the RGJ, as shown in box 706, the controller determines that the access device may be in the lungs and may instruct the user to retract the device, as shown in box 708. If the temperature fluctuations are not detected, as shown by box 710, the controller may confirm that the device is correctly placed in the stomach as shown in box 712.
Other sensors, in addition to, or instead of, impedance/conductivity sensors and temperature sensors may be used to determine the location of the gastric access device within the anatomy. For example, electrocardiography (ECG) sensor or sensors may be used to determine whether the gastric access device is above or below the heart. If the device is below the heart, it is not likely in the lungs or trachea, and is therefore likely in the stomach.
The ECG sensors will sense electrical activity of the heart, including, for example, a signal including a P zone, Q zone, R zone, S zone, T zone, U zone, origination of the signal etc. The signal will have a magnitude and frequency, and the various zones may include peaks of various positive and negative magnitudes. The gastric access device may have 2 or more ECG sensors on the device itself, such as sensors 804. Alternatively, the gastric access device may have 1 or more ECG sensors, and the system may include external ECG sensor 806. The external ECG sensor is also in electrical communication with the monitor either by wire or wirelessly. As the gastric access device is advanced, the ECG signal may be continually received by the monitor. Because the ECG sensors are sensing electrical activity of the heart, the signal will change as the sensors traverse through the esophagus, past the heart toward the stomach. These changes may be in magnitude or direction (positive or negative) of one or more of the zones of the ECG signal. The changes may be different depending on the location of the ECG sensors within the system. For example, a system with one ECG sensor on the feeding tube, and one ECG on the sternum, may show a different change than a system with 2 or 3 ECG sensors on the feeding tube. Although the change may vary depending on the system configuration, the change is detectable by the controller for a given system configuration as the sensors pass the heart because of the change in relative location of at least one or more of the ECG sensors (the sensor(s) on the feeding tube) with respect to the heart.
The ECG sensors may be used in conjunction with any other sensors, including impedance/conductivity sensors and/or temperature sensors or other sensors to help locate the gastric access device in the stomach. Any of the sensor types may share the same electrodes with other sensor types.
If the controller receives signals from the ECG sensors showing that the device is below the heart, as shown in box 1014, the controller may indicate to the user that the device is likely in the stomach. Alternatively or additionally, the controller may use the signals from the conductivity sensors to confirm placement. If the controller has not received a signal from the impedance sensor(s) on the device indicating high conductivity, or low impedance, as shown in box 1016, then the controller may indicate to the user to retract the device, as it is possibly not in the stomach, as is shown in box 1018. However, if the impedance sensors have received a signal from the impedance sensor(s) on the device indicating high conductivity, or low impedance, as shown in box 1020, then the controller will indicate to the user that the device is likely in the stomach, as shown in box 1022.
If, during device advancement, the sensors first sense high conductivity, as shown in box 1004, it is possible the gastric access device is in the stomach. The controller may indicate that the device is in the stomach, and/or the controller may analyze ECG sensor signal data to determine whether the ECG signal signature shows the device has passed the heart. If this signature is detected, as shown in box 1006, the controller determines and communicates that the access device is likely in the stomach, as shown in box 1008. If the ECG sensor signal signature indicates that the device has not passed below the heart, as shown by box 1010, the controller may indicate that the device may not be in the stomach and may indicate to retract the device and re-advance, as shown in box 1012.
Steps 1006 and 1014 (and similarly, step 704, in
Although the flow charts have shown the flow of embodiments with two types of sensors, where one type of sensor may confirm or question device placement based on the other type of sensor, it is understood that embodiments of the gastric access device may incorporate one, two, three, or more types of sensors. The sensors may operate independently, for example with certain patient types or in certain environments, or may operate in concert, as shown in the flow charts herein. Additionally, not all the sensors may be used for all patients. For example, embodiments of the device may include 3 types of sensors, for example, temperature, impedance/conductance and ECG sensors. One, two, or three types of sensors may be used for different patients and/or different environments. For example, 3 sensors may be used on most patients, but in a warm room, the temperature sensor may not be used. As another example, ECG sensors may not be used on a patient with a known arrhythmia. In some embodiments, there are two types of sensors so that one or two types may be used in the majority of patients and environments. In some embodiments there are two or more types of sensors for placement confirmation redundancy.
One or more temperature sensors may be placed so that it is in the trachea if the distal tip of the device is in the lungs. For example this sensor may be placed at around 250-350 mm from the distal tip. Alternatively, this sensor may be placed at around 200-400 mm from the distal tip. Alternatively, this sensor may be placed at around 100-150 mm from the distal tip, for smaller patients. Alternatively, this sensor may be placed at around 100-200 mm from the distal tip.
In some embodiments, one or more temperature sensors may be placed on the outside of the gastric access device. In some embodiments, one or more temperature sensors may be placed completely within the wall of the gastric access device. In some embodiments, one or more temperature sensors may be placed within the wall of the gastric access device, so that the temperature sensor is exposed on the outside of the device.
ECG sensors and/or temperature sensors may be separate from impedance/conductance sensors, or may utilize some or all of the same electrodes. In embodiments where the same electrodes are used, different types of sensing (i.e. temperature, ECG and impedance/conductance) may alternate with the same electrodes, or be used at different locations, or points in time, of the procedure, or with different patients. Different or the same lead wires may be used for the different functions of a single electrode. Any of the sensors may utilize electrodes which completely encircle the device, or which only partially encircle the device.
Placement display area 1402 may include a graphic representation of the anatomy, including the esophagus, the stomach and the lungs/trachea. This display may include colors to indicate correct, questionable, and incorrect placement. For example, if one or more types of sensors sense that the device is in the stomach, the stomach may flash or show green. If one or more types of sensors sense that the device is in the lungs, the lungs may flash or show red. If neither the stomach nor the lungs has been sensed by any type of sensor, the esophagus may flash green, or another color to indicate to the user to continue advancing. The distance the device has traveled into the patient may be incorporated into the placement assessment. In some embodiments, the controller in in communication with a sensor, such as an optical sensor, which automatically measures the length of the device which is in the patient. If there are conflicting signals from sensor types, or from any one sensor type, the corresponding area of the body may flash or show orange.
Further information may be displayed elsewhere on the monitor. In some embodiments, a body area indicator may flash, and then turn solid, as information is confirmed. For example, if the device is advanced into the stomach, and an impedance sensor senses higher conductivity, the stomach shape may flash green (or otherwise indicate to the user to pause the advancement of the device, or pause before the user or the controller initiates feeding), showing that preliminary the controller has determined that the device is in the stomach. The controller may then continue to collect temperature sensor data over a few to several seconds. If this data shows that the device is not likely in the lungs (no fluctuations associated with breathing), the stomach shape may turn solid green instead of flashing green (or a pause indicator may go away), allowing the user to initiate feeding or continue advancing the device.
Alternatively, if the temperature sensor show that there are temperature fluctuations, the stomach shape may turn orange or red, indicating a possibility of being in the lungs. Additionally or alternatively, the lungs may turn red or orange in this scenario. The controller may indicate to the user to retract the device and/or may prevent the feeding function from being initiated.
The pause to collect temperature data may be at least 1 second, at least 3 seconds, at least 5 seconds, at least 7 seconds, at least 10 seconds, at least 15 seconds, etc. The pause may be in the form of an indication to the user to not advance the device and/or not to initiate feeding through the device. The pause may cause the controller to prevent initiation of feeding through the device until after the pause has ended and the stomach has been positively identified and confirmed.
Other possible indicators which may be displayed on the display and/or audibly played and/or felt (such as a vibration) include:
In some embodiments, placement display 1416, and/or other displays, are alternatively, or additionally on feeding tube 1412, and/or on remote device 1418, such as a mobile phone, tablet, computer, server, electronic medical record, etc. In some embodiments, the controller functions are fully, or partially included in the remote display. For example, some embodiments of the device may not include monitor enclosure 1410, but include a stand-alone feeding tube 1412 with display 1416. This smaller display may be fulling portable and may incorporate all or some of the monitor/controller functions. Some of the monitor functions may be incorporated into remote electronic device 1418. Feed input line 1414 is also shown. Monitor enclosure 1410 may include a docking area on which the feeding tube may be docked, so that the feeding tube may operate with placement display 1416, or with the full monitor display contained by enclosure 1410, if the feeding tube is docked in the monitor.
Other display areas not shown here may include data views, such as temperature data view and/or ECG data view which shows a graph of the signal from a type of sensor. Other display areas may include reflux information including risk, events, management and contextual (i.e. historical) info and trends.
The feed rate may be dependent on the sensed GRV/gastric emptying and may be controlled automatically by the controller or semi-automatically or manually. Semi-automatic control may include automatically controlling smaller adjustments but prompting the user for larger adjustments.
In some embodiments, the diameter of the shaft of the device may be larger at the location of the tissue sensing electrodes, than over other areas of the device. In some embodiments, the diameter of the shaft of the device at the location of the tissue sensing electrodes may be expandable and/or retractable, such as a cage, or balloon to increase tissue contact.
For example, the UES may be identified if the sensor is around 15-20 cm into the body (measured from the incisors). The LES may be identified if the sensor is around 30-50 cm into the body. They pyloric sphincter may be identified if the sensor is around 50-100 cm. These measurements targets may be narrowed by taking into account the size of the patient. Note that different tissue electrodes/sensors may be used along the length of the device shaft to identify different areas of the anatomy. The diameter, or the distance that the tissue electrodes protrude from the shaft, may also be used to determine which sphincter the electrodes are sensing.
This embodiment may or may not include impedance/conductance electrodes 1108 as well as temperature sensors 1110. In some embodiments, electrodes 1502 may be used for determining GRV/gastric emptying, or device placement, in addition to sensing impedance/conductivity of tissue.
Some embodiments of the gastric access device include the ability to avoid reflux events, sense reflux events or migration of the device, and manage reflux events, for example by suctioning the reflux material from the patient. The same sensors used for positioning may be used for this, or other sensors may be used.
When a reflux sensor is in the presence of reflux fluid, the conductivity will increase, and the impedance will decrease. Because it may be advantages to avoid contact between the reflux sensor and the tissue of the esophagus, reflux sensors 1602 may be placed in recesses 1604 of the device outer shaft. This is shown in cross-sectional
Some embodiments may include suction tube 1704 without expandable member 1702. In these embodiments, the suction level may need to be controlled so that stomach contents are not suctioned into the esophagus. The suction tube may be located anywhere at or above the LES. In some embodiments, the suction tube may be moved along the shaft to precisely locate the suction. This locating of the suction tube may be determined by the level of reflux, which may be determined by the signals from the multiple reflux sensors along the length of the shaft of the device.
The suction lumen of the suction tube is connected to suction device 1802. Suction device 1802 may be a pump, or may be a valve controlling wall suction or may be another suction mechanism. Suction line 1804 may or may not run through hub 510.
In some embodiments, suction of reflux is initiated and/or continued based on the signals from the reflux sensors, indicating that reflux is present in the esophagus. In some embodiments, the controller/monitor may be programmed to periodically apply a small amount of suction to the suction device to remove any reflux that may or may not be present, and/or test for reflux. This periodic application of suction may occur whether or not reflux is sensed. The expandable member may or may not be expanded for these periodic suction events. By performing periodic suction events, the system can effectively remove reflux risk without relying on sensing the reflux. Preferably, these periodically scheduled reflux suction events apply a low enough level of suction that stomach contents are not suctioned up in embodiments where the expandable member is either not present or not expanded. If reflux us sensed (either in the anatomy, or in the suction tube or elsewhere), or collected during a periodically scheduled reflux suction event, then the controller may be programmed to increase or prolong the suction event to make sure that all the reflux is suctioned. The controller may also trigger an expansion of the expansion member if the reflux suction event is increased in level of suction or prolonged.
Embodiments which include periodically scheduled reflux suction events, may not include reflux sensors on the device. Although they may include other reflux sensors to determine whether reflux is being suctioned out of the body. For example, reflux sensors may exist outside of the body, in the controller, waste receptacle, suction line, hub, etc. Periodically scheduled reflux suction events may be scheduled every 5 minutes, every 10 minutes, every 30 minutes, every 60 minutes, or every 5-30, or every 30-60 minutes, or any other appropriate time frame. The schedule may be scheduled by the user. The interval may change depending on past reflux events. For example, the scheduled reflux suction events may become more frequent if reflux is sensed once or more than once. This change may be manual or automatic.
In some embodiments, a low level of suction may be used on a continuous or semi-continuous basis. In these embodiments, the expansion member may not be expanded during the continuous suction, so that the esophagus is not blocked off for long periods of time. This continuous mode may be activated during feeding, at all times, or as a result of one or more reflux events.
In some embodiments, the expansion member may be expanded and block off the esophagus for longer periods of time, essentially acting as an artificial LES to prevent reflux.
Embodiments shown herein, such as those shown in
In some embodiments, placement of the device at or past the pyloric sphincter may be identified or confirmed by other methods. These same methods may also be used to place the device in the stomach. For example, pH sensors may determine that the access device is post pyloric or elsewhere. The various sensors disclosed herein may be used to pick up certain signatures, such as pH fluctuations, absolute or relative temperature, peristalsis, impedance/conductivity, etc. ECG sensors may be used to determine a changing ECG signal as the electrodes on the device move through the anatomy. For example, the ECG signal may change as the device passes the patient's mid-line. A bright, or otherwise detectable light may be used on the device which can be detected through the skin to identify that the distal end of the device is in the intestines. Electrodes on the device may be used to sense proximity to each other, via impedance, conductivity, or other methods, which can indicate when the device is in a tight curve, i.e. one part along the length of the device is in relatively close proximity to another part along the length of the device. For example, see the embodiments disclosed in
In some embodiments, navigating the gastric access device to and/or past the pyloric sphincter may be aided by implementation of different device tip shapes and/or designs, such as a pigtail tip, a weighted tip, or an articulating tip. An articulating tip may have circumferential impedance sensors on it to sense tissue contact on one or more sides of the tip. The tip may be navigated away from the tissue contact to seek out the pyloric opening. Some embodiments may include a vibrating end or rotating end to seek out the pyloric opening.
Some embodiments of the system may include the ability to inject fluid through a lumen of the device which serves to prevent the distal end of the device from embedding in tissue and also serves to stiffen the device during advancement. The pressure of the fluid exiting the device may be controlled so that it does not damage tissue, but is high enough to serve its purpose. The fluid may exit the device via a distal facing opening, one or more side opening(s) and/or other opening configurations.
Any of these tip shapes and/or technologies may be included in a feeding tube, or in a stylet that passes through a lumen of a feeding tube, or next to a feeding tube, to guide the feeding tube over the stylet to access the small intestines via the pylorus. The stylet may be removed, or may not be removed after placement.
Some embodiments may include direct visualization, such as a camera or fiberoptics to determine and/or confirm placement of the device in the desired anatomy.
Some embodiments may include the ability to differentiate between the esophagus and the trachea by sensing the amount of air/gas suctioned into the device when a vacuum is pulled through the lumen of the device. The ability to suction air/gas into the device will be greater in the trachea than in the esophagus. To avoid the device abutting tissue when a vacuum is pulled, one or more small puffs of air or fluid may be introduced through the device before a vacuum is pulled. Alternatively or additionally, openings around the circumference of the shaft of the device may be used.
Some embodiments may measure myoelectrical activity using electrodes. This may be used to help place the device in the desired location.
Any of the embodiments disclosed herein may automatically suction reflux from the esophagus of the patient based on the sensing of reflux, or based on a reflux suctioning schedule.
Sensors incorporated into the gastric access device may collect data continuously, intermittently, on demand, or only at certain times, for example when confirmation of placement is necessary.
Devices disclosed herein include nasogastric tubes with sensors configured to aid in placement of the tube in the stomach, avoiding accidental placement in the trachea or lungs.
These sensors may include temperature sensors for sensing fluctuations due to breathing, and impedance/conductivity sensors for sensing the stomach. These sensors may alternatively include temperature, impedance/conductivity and ECG. These sensors may alternatively include any two of temperature, impedance/conductivity, pressure, humidity, pH, ECG. These sensors may alternatively include any three of temperature, impedance/conductivity, pressure, humidity, pH, ECG.
Electrogastrogram (EGG) may also be used to identify the location of the gastric access device in the stomach. EGG sensors may be different than other sensor types, or may use the same electrodes as, for example, the ECG sensors and/or the impedance/conductivity sensors.
In some embodiments, electromagnetic sensors may be used in addition to other sensors for placement.
Although embodiments disclosed herein discuss accessing the GI tract and avoiding the trachea/lungs, the same concepts can be used to locate the trachea/lungs and avoid the GI track.
In some embodiments, a bubble similar to bubble 2104 may be used to measure pressure fluctuations which can aid in confirming placement of the device in either the esophagus or the trachea.
Some embodiments of the Gastric access device may include the ability to test whether the feeding tube is bent or kinked. In one embodiment, the controller may introduce pressurized fluid (gas or liquid) into a lumen of the feeding tube and measure the pressure required for the fluid to flow through the lumen. A baseline pressure may be detected on a non-bent feeding tube to determine the unkinked pressure range. If/when the tube is bent or kinked, the pressure required will increase. The controller can measure and track this pressure over time and can determine the status of the feeding tube based on the absolute pressure, the relative pressure, the change of pressure or the slope of change of pressure over time.
Bending or kinking of the feeding tube may also be measured electronically, for example by measuring the proximity of the electrodes to each other. If the electrodes are closer to each other than their spacing along the feeding tube, then a kink or tight bend is likely present in the tube. This can be done by measuring impedance and/or conductance between electrodes. The pairing of electrodes can be altered by the controller to determine electrode proximity. Alternatively, the same electrode pairing may be used.
For example, see
In some embodiments, the bend/kink of the device may be so extreme that two electrodes on the device come into contact with each other and short out the signal. This information may be used to assess kinking.
In some embodiments, a piezoelectric member may be incorporated into the device to determine the orientation of the device (including whether it is bent/kinked or not) by monitoring the changes of the electrical properties of the piezoelectric member.
In some embodiments, one or more strain gauges may be used to assess kinking/bending of the device.
In some embodiments, one or more accelerometers may be used to determine the orientation of various parts of the device. In some embodiments, a weighted tip may be used to determine orientation of the tip of the device.
In some embodiments, one or more pressure sensors are used for placement of the device. For example, the pressure exerted on the device in the stomach may be higher than that in the esophagus. In embodiments with more than one pressure sensors, a lack of difference between the two pressure readings may indicate that one pressure sensor is in the stomach, while one is in the esophagus. Two similar pressure readings may indicate that the device is kinked in the esophagus.
In some embodiments, a conductive fluid injection may be used to assess bending/kinking of the device. Following placement, conductive fluid may be injected into the patient's mouth. In situations where the device is not bent back upon itself in the anatomy, the electrodes will read increased conductivity signals by electrodes more proximal first, and then progressively more distal. Where the device is bent back upon itself, the distal electrodes may signal increased conductivity out of order, so before some of the more proximal electrodes. Similarly, a device may use temperature sensors and hot or cold liquid to perform a similar assessment.
Some embodiments incorporate automatic air insufflation to reduce device kinking. The controller automatically injects a stream, or puffs of air through the device as the device is being inserted. This air or gas serves to stiffen the device and prevent kinking during insertion. This process may automatically occur during the entire insertion process, or only once resistance is perceived, or once the device is a set distance within the patient.
In some embodiments pressurized air or fluid may be used within a lumen of the device to stiffen it as an alternative to, or in addition to using a stylet.
In some embodiments, the device may be vibrated or rotated automatically during insertion to prevent kinking.
In some embodiments, the distal tip may have a corkscrew shape and may be rotated during insertion.
Some embodiments may include a balloon, or other expandable member, to prevent accidental withdrawal of the device once it is placed. The gastric access device may have a balloon that is inflated against the esophagogastric junction following insertion into the stomach to prevent curling back into the esophagus or inadvertent withdrawal.
Any of the embodiments which include the ability to determine bending/kinking of the device may also be used to assess the shape of the device within the anatomy. In other words, these embodiments may be used for generally device shape modeling, in addition to bend/kink detection.
Based on these lengths, the gastric access device can be designed to have the correct type of sensors in the appropriate anatomy during placement, and during ongoing use.
In some embodiments, it is desirable to have one temperature sensor as close to the distal tip of the device as possible, without being so close to the distal tip that the temperature sensor is generally up against tissue during advancement. This distal-most temperature sensor will aid in placement of the device. As the device is advanced, the distal-most temperature sensor will sense temperature fluctuations, or a lower temperature, associated with breathing ambient air while the sensor is above the RGJ. As the device is advanced further, the temperature fluctuations should flatten out, or the average temperature will increase, if the device is advanced into the esophagus. If, however, the device is advanced into the trachea, which is undesirable, the distal-most temperature sensor will continue to sense temperature fluctuations and/or a lower temperature than body temperature as it is advanced into the trachea. This undesirable advancement will trigger the controller of the system to warn the user and instruct the user to retract the device.
In some instances, the gastric access device may undesirably be in the trachea, but the distal-most temperature sensor may be up against tissue and therefore not sensing temperature fluctuations or a temperature lower than body temperature. The second, more proximal temperature sensor is placed so that it will sense temperature fluctuations, or a temperature lower than body temperature, if the device is misplaced in the trachea. It is desirable that the more proximal temperature sensor be placed along the length of the device such that it has advanced past the RGJ before the distal end of the device passes excessively into the bronchi.
Two temperature sensors are shown here, but fewer or more may be along the device. In some embodiments, each electrode on the device can sense impedance/conductivity, temperature, ECG and in some cases other parameters. The function of the different electrodes may be controlled by the controller. Sensed parameters may alternate throughout placement and use, or sensed parameters may be linked to the size of the patient, or length of the anatomy.
For example, a gastric access device may include 10 pairs of electrodes. The patient may be a tall adult. Based on the patient's height, or other measurement of the patient, the electrodes along the device may be assigned appropriate functions so that there is at least a distal-most temperature sensor, and a proximal temperature sensor, that will allow the device to sense temperature fluctuations and/or average temperatures in the trachea or esophagus, while the device is being introduced into the patient. In some embodiments, the proximal temperature sensor is located so that it is past the RGJ before the distal-most temperature sensor has advanced too far into the bronchi. In some embodiments, the distal-most temperature sensor is proximal to the distal-most electrode pair. In some embodiments, the distal-most temperature sensor is incorporated into the distal-most electrode pair.
Additional electrodes may be proximal to the most proximally used electrode. These electrodes may be useful in taller or larger patients, but not in shorter or smaller patients. In this way, the same device may be used with patients of different sizes and anatomies.
Temperature, impedance/conductance, ECG, pH and other sensors disclosed here, may also be used along the length of the device to sense any type of placement, including post pyloric placement. For example, the device may have electrodes along a significant portion of its length, allowing the controller to receive sensor signals from all parts of the anatomy in which the device is located as it is advanced or after it is advanced. The controller may create a temperature map, an impedance/conductivity map, an ECG may, a pH map, a combination parameter map, etc., the signature of which can be analyzed to determine the likely location of each electrode within the anatomy. This will allow the user to know where the tip of the catheter is, the openings for feed, etc.
The leads generally run along the length of the device as is shown in
Switch 2910 may connect other logic/sensing areas, such as ECG, pH, etc., which may be use overlapping electrodes, similar to temperature and conductivity/impedance do here. In the case of pH sensing, a reference material would be incorporated into the system to determine pH using the electrodes. ECG and pH sensors may use the same leads as impedance/conductivity sensors.
In some embodiments, no physical or logical switch is necessary, the functions of the various leads/electrodes are driven by logic within the controller. Sensing two different parameters with the same electrodes may even overlap in time, for example, the controller may sense both temperature and impedance from the same electrodes at the same time. The controller may sense temperature, impedance and ECG at essentially the same time, if sampling rates allow. For example, sampling rates may be greater than 5 samples/second. Or for example, sampling rates may be greater than 10 samples/second. Or for example, sampling rates may be greater than 20 samples/second. Or for example, sampling rates may be greater than 100 samples/second.
Another advantage of using a 360 degree, or substantially 360 degree conductive band for these types of sensors is the following:
Each sensor impedance/conductivity sensor (which is generally made up of two electrode rings, but may be made up of one, two, or more electrode rings) seeks to measure the path of minimum impedance, or maximum conductivity, between the two rings. This means that the impedance/conductivity sensor is simultaneously sensing 360 degrees around the circumference of the rings. If, for example, the two rings of an impedance/conductivity sensor are up against the gastric wall, the gastric wall tissue will only be contacting one side of the feeding tube and therefor one side of the electrode rings. The sensor will sense the high conductivity/low impedance of this contact, even though a large portion of the circumference of the rings may not be in contact with a high conductivity/low impedance environment. In other words, the impedance/conductivity sensor using the 360 degree rings, is essentially a spot sensor.
In contrast, each temperature sensor may be made up of a thermocouple bonded to a 360 degree electrode or conductive ring. Due to this bond, the thermocouple is essentially sensing the average temperature around the circumference of the ring. In the situation where the feeding tube, and thus the temperature sensor is pressed up against tissue, the temperature sensor will sense an average temperature of the tissue as well as the environment surrounding the rest of the circumference of the ring. This allows the temperatures sensors to sense breathing in the respiratory system even when the feeding tube is up against the wall of the respiratory system, avoiding false negatives. In other words, the temperature sensor using the 360 degree ring is essentially an environmental average sensor.
By using the same electrode for both sensor types, the system can sense both tissue contact (by switching to conductivity/impedance sensing) and temperature environment (by switching to temperature sensing). The controller may switch back and forth between the two depending on the current need and/or location of any particular sensor.
The controller may determine impedance by measuring the voltage drop (amplitude of the cyclic voltage signal) across an electrode pair when a constant-amplitude AC current is applied. For example, the AC current may be 30 kHz, 100 μA peak-to-peak. Temperature measurements may be obtained by using Copper/Constantan thermocouples (Type T) that are thermally bonded to one electrode ring. This design solution provides 360 degree sensing to facilitate acquisition of true impedance and temperature measurements even with intermittent tissue contact or other confounding factors. The sensor positions are designed to accurately classify the anatomical location of the device based on each sensor's measurement of the local environment. The gastric access device can be different lengths to allow optimal sensor spacing based on the clinical nose-car-mid-umbilicus (NEMU) method commonly used for determining insertion length to ensure final optimal positioning of the sensors within the patient's upper gastrointestinal (GI) Impedance and temperature data may be delivered to the controller in real-time via a secondary non-fluid-contacting lumen. The sensor data may be analyzed by the controller for two different functions: placement (during the device insertion, or for periodic monitoring of position) and gastric status (for determining GRV gastric emptying etc. during feeding).
The placement function may use a simultaneous two-part analysis to classify device location: (1) a time-series temperature pattern recognition function and (2) an impedance threshold classifier (ITC) for identifying device tip placement within the esophagus, stomach, or respiratory system or elsewhere.
The temperature pattern recognition function may assess temperature data from sensors T1 and T2 at a rate of around 5 Hz to detect device misplacement into the airway through the identification and classification of consecutive local maximum and minimums (LMMs). Once the temperature pattern recognition function recognizes a pattern in the LMMs representative of two respiration cycles (typically occurs within 2-4 s in infants, longer in adults), positive determination of airway misplacement may be determined.
Simultaneous to, or interspersed with, temperature analysis, the placement function continuously or intermittently assesses impedance measurements along the device. Impedance measurements in the stomach are generally significantly lower than in the esophagus. In some embodiments, a single threshold of 350Ω is sufficient to differentiate between the stomach and esophagus. In some embodiments, a threshold classifier that defines location is based on the impedance measurements of at least two of three distal sensors. This provides a robust approach to ensure proper placement even in the presence of confounding factors including intermittent tissue contact or air bubbles within the stomach.
Note that a cut off of 350Ω is shown here, however the cut off may be within a range of about 350Ω-400Ω. Alternatively, the cut off may be within a range of about 350Ω-450Ω. Alternatively, the cut off may be within a range of about 350Ω-500Ω. Alternatively, the cut off may be within a range of about 350Ω-650Ω. Alternatively, the cut off may be within a range of about 300Ω-400Ω.
The gastric status function calculates the patient's real-time stomach content composition based on: (1) the impedance measurement of the patient's empty stomach prior to any feeding (the measurement may be taken with one or more of the most distal electrode pairs), (2) the impedance measurement of the formula being delivered (sensed using the internal sensor within the device lumen), (3) the real-time average impedance value within the stomach (sensed using one or more of the more distal electrode pairs), and (4) the selection of the appropriate calibration curve from a library. Shifts in stomach content composition pattern characteristics may be evaluated over 4-, 8-, 12- and 24-hr windows using both time-series and latent variable trend analysis to provide automatic feedback on gastric status. Different status categories may include: 1) feeding is optimized, 2) low-risk of feeding intolerance (advance feedings if caloric goal has not been achieved) and 3) high risk of feeding intolerance (reduce feedings if there are clinical signs of feeding intolerance).
The placement and gastric status function outputs are visually displayed on the controller to provide real-time feedback to clinical staff. The reusable pole-mounted controller includes a user-interface display, and may be powered by a standard outlet and may contain an internal battery capable of supporting 12 or more hours of continuous function. For initial device placement, the operator may receive the following notifications: (1) ORANGE ESOPHAGUS: “Distal tip of the device is in the esophagus. Continue advancing”, (2) RED LUNGS: “Distal tip of the device has entered the respiratory tract. RETRACT”, (3) GREEN STOMACH: “Distal tip of the device is properly placed in the stomach”. Once correct gastric placement has been achieved, the gastric status function of the controller will continuously monitor for changes in digestion and provide automatic feedback on how best to optimize feeding: 1) feeding is optimized, 2) feeding intolerance risk is low (advance feeding), and 3) feeding intolerance risk is high (reduce feeding).
In some instances, a user may introduce medication through the feeding lumen of a feeding tube. This medication may take the form of crushed pills or other bulky substances. The feeding lumen of the feeding tube can often become blocked because of added medications, which can be difficult to unblock. To prevent large particles of medication from entering a feeding tube, an anti-clogging mechanism may be used in conjunction with the gastric access device, or any feeding tube.
Crusher accessory 3002 is connected to the feeding tube or gastric access device as shown in
Other embodiments of an anti-clogging mechanism might include sharp blades to cut larger chunks of medication which are forced through the opening.
Introducer accessory 3010 is connected to the feeding tube or gastric access device as shown in
The controller of any of the embodiments disclosed herein may include the ability to analyze and/or display contextual data. For example, reflux history may be collected, analyzed, displayed and used to automatically control the controller. For example, a patient with a higher incident of reflux may require more frequent or continual suction events. The controller may take into consideration the extent and/or frequency of reflux events to determine the reflux suction schedule and/or suction level. The contextual reflux information may also determine whether or not the expandable member is expanded during suction events. Contextual feeding, GRV, placement information may also be used in this manner.
In some embodiments, the gastric access device may use electrodes along the device to sense passive electrical signals generated in the walls of the stomach. These signals can be used to assess gastric health, such as peristalsis.
GRV/gastric emptying may be tracked by the system over time by introducing an additive element with a measurable parameter where the parameter is at a level that is different than that of the stomach contents. The parameter level is sensed by sensors on the feeding tube and changes analyzed over time to determine GRV/gastric emptying. For example, a fluid with a conductivity that is lower than that of stomach contents (such as feed) may be introduced into the stomach, either as a bolus, multiple boluses, or continually or over time. The sensors along the gastric access device may be conductivity/impedance sensors and can sense the conductivity/impedance along the device over time to determine GRV/gastric emptying. Other parameters may also be used, such as temperature, pH, chemical content, optical parameters, etc.
In some embodiments, a sensor is also present inside the additive element delivery lumen of the device, which may be the feeding lumen or may be a separate lumen. This sensor(s) may measure the parameter of the additive before it is added to the stomach so that the parameter level of the additive is known before it is introduced into the stomach. This allows the controller to determine GRV/gastric emptying more accurately. For example, in the conductivity/impedance example above, a pair of electrodes may be present inside the feed lumen of the device and measure the conductivity/impedance of the additive (which may be feed) just before it enters the stomach. The electrodes may be flush with the inner surface of the feeding lumen. This measurement can be factored into the GRV/gastric emptying analysis so that the change in the parameter due to the stomach contents can be accurately determined. This inner lumen sensor may be considered a “calibration sensor”.
In some embodiments, the controller switches to feed mode, to monitor GRV, after it senses feed or liquid within the feeding lumen of the device.
When the gastric access device is in feeding mode, it may place itself in different states, for example, feeding optimized, low-risk of feeding intolerance (advance feedings if caloric goal has not been achieved) and 3) high risk of feeding intolerance (reduce feedings if there are clinical signs of intolerance). In some embodiments, the gastric access device may be able to measure the % concentration of food vs. gastric fluid in the stomach, based on measuring a parameter of the additive (in this case food) over time. These embodiments may include calibration sensors.
In some embodiments, digestive health may be assessed by providing a bolus of an additive element and tracking the GRV/gastric emptying immediately following the bolus. The GRV/gastric emptying profile can be used to determine a particular patient's health by comparing the profile to those of healthy and unhealthy individuals and/or populations. For example, an additive bolus with a high level of glucose may be used and the GRV/gastric emptying monitored after the bolus. Other indicators may also be monitored, such as blood glucose level, etc.
In some embodiments, GRV (or gastric emptying) is monitored over time, and feeding is stopped, started, increased or decreased as a result of changes in GRV over time, or GRV thresholds. For example, if GRV is decreasing, this may be an indicator that the patient can tolerate more food, and feeding rate and/or volume may be increased or initiated. If GRV is increasing, this may be an indication that the patient is not tolerating the feed rate and feeding rate and/or volume may be decreased or stopped. Feeding rate and/or volume may be increased, decreased, stopped or initiated based on GRV trends and/or GRV thresholds.
Feeding rate and/or volume may be changed by changing the speed of a feeding pump, or by closing off a source of feed, or opening a source of feed, either intermittently or for a period of time or until a user initiates or stops feeding again. Closing or opening a source of food may be done via a valve in-line with a feed supply line.
In this way, optimal feed rate and/or volume can be achieved. The feed rate target may be the feed rate at which GRV stays relatively steady, not increasing or decreasing appreciably over time. This rate may be different at different times of day, when the patient is awake, sleeping etc. The feed rate may be determined by the change in GRV at any given time. In this way, food tolerance can be determined specifically for each patient, and specifically for a single patient at different times and for different environments.
An estimate of feed rate to achieve steady or constant GRV over time may be achieved by measuring the impedance of an empty stomach, as well as knowing or measuring the impedance of formula. For example, if the impedance measurement in an empty stomach is around 200-300 ohms, and the impedance of the introduced formula is 800 ohms, then the target impedance may be an approximate average between these two numbers, or around 500-550 ohms. The target impedance may also be lower or higher than the average between the two measurements.
In situations where bolus feeding, or intermittent feeding, or even steady feeding with a peristaltic pump is used, the impedance within the stomach may oscillate or vary during feeding. In these situations, the target impedance to achieve steady GRV over time may have an upper and lower limit, which achieves an averaged steady GRV over a period of time.
The target impedance may need to be adjusted based on water consumed.
In some embodiments, the patient may be purposely placed into a fasted state over time. The system may be recalibrated to match an impedance (and potentially temperature) to a fasted state, which may change over time, due to biofilm buildup or other factors. This new fasted state impedance (and/or temperature) reading may be used to determine GRV (or core body temperature).
In some embodiments, the type of feed may be altered based on monitoring of GRV or other parameters. For example, multiple food reservoirs may be accessibly by the system. The food reservoirs may differ in terms of protein, fat, caloric and/or carbohydrate content/density/ratios. A patient may tolerate a certain type of food better than others, or may tolerate different types of foods at different times of the day, or while sleeping, awake etc. For example, if GRV is increasing over time, the system may switch to a feed lower in fat and/or protein to potentially increase the digestion rate. The altering of feed type may be used separately or in conjunction with altering the feed rate as mentioned above.
In some embodiments, a fourth component may be adjustable in the feed, such as water, or another liquid. This fourth component may be able to adjust the impedance/conductivity of the feed as well as the temperature of the feed. For example, at least four components may be controlled in the feed, potentially with separate reservoirs: fat, carbohydrates, protein, and liquid. The liquid may be non-nutritious or nutritious. In some embodiments, the amount, or ratio, of the liquid component delivered in the feed may be determined by the sodium concentration in the urine, sodium concentration in the blood, or other factors. In some embodiments, the amount, or ratio, of carbohydrates delivered in the feed may be determined based on glucose level in the urine, glucose level in the blood, ketone level in the urine, or other factors.
In some embodiments, a proprietary pump is incorporated into the system with a known volume delivery rate. In some embodiments, volume delivery rate from other third party pumps is entered into, and/or stored in the memory of the controller of the system so that feed delivery rates are accurate.
In some embodiments, a bolus of feed is used to determine gastric emptying/GRV. The bolus may be a known quantity with a known indicator parameter value. Changes in the indicator parameter (such as conductivity, pH, temperature etc.) measured over the following minutes allow the controller to obtain an accurate measurement of GR V based on these changes—the magnitude of change as well as the change over time, shape of the curve representing change over time, etc.
In any of the embodiments disclosed herein, when reflux is detected, GRV is increasing or higher than a threshold, or the device migrates from its proper location, the controller may cause feeding to slow or stop, and may provide an alert.
In some embodiments, temperature measured by temperature sensors along the device is used for one or more purposes. Temperature readings may be used to determine when feed has been administered through the feeding tube. Feed is generally at room temperature and at a lower temperature than the subject's body, therefore the temperature sensors will detect a reduction of temperature after a bolus of feed is administered. The temperature sensors may also detect a temperature lower than body temperature over time during constant feed. The fluctuation in temperature readings may be associated with feeding events and may be used to differentiate between feeding tube displacement events and feeding events, as determined by impedance/conductivity sensors. For example, impedance sensors may sense an increase in impedance, either if the feeding tube is displaced, or when a bolus of food has been administered through the feeding tube. Readings from temperature sensors can differentiate between the two conditions—temperature will be reduced during a feeding event, where it will generally not be reduced, or reduced less, during a displacement event.
Some embodiments may include the ability to “ignore” temperature changes during feeding events, for the purposes of measuring patient body temperature. For example, body temperature readings may be suspended immediately after a feeding event. This may occur automatically, based on a sensed sudden decrease in temperature associated with a feeding event, or may occur by a user entering a feeding event into the controller, for example by pushing a button on the screen saying “feeding imitated”. The suspension may last a fixed period of time, for example around 5 minutes, or may last until the user pushed an “end” button, or may last until the controller determines that the temperature readings are close enough to where they were before the feeding event, based on the actual temperature measured, the slope of the temperature over time curve, or a different analysis. Some embodiments may account for an offset in temperature measured due to continual feeding in determining the body temperature. Changes in impedance/conductivity readings on the various sensors may also be incorporated into these analyses.
Some embodiments may incorporate a pause in feeding to determine core body temperature, to minimize the effect of feed temperature on the core body temperature readings. For example, the controller may control a pump, which pauses feeding at preset, or random, or manually set time periods, for a long enough period for the temperature sensors to sense core body temperature, and not be affected by added feed temperature. This period may be around 5 minutes, or may be around 10 minutes or other time frame. Alternatively or additionally, the controller may sense a stabilization of the temperature curve after feeding has been stopped to determine that the temperature sensors are sensing core body temperature, and the temperatures sensed are no longer affected by feed temperature.
Some embodiments include multiple temperature sensors along the length of the device. The changes in temperature due to added feed may be different at different times as sensed by the different temperature sensors along the length of the device. For example, a distal temperature sensor (further inside the stomach) may take longer to recover to body temperature than more proximal temperature sensors. This difference may also be factored into any analysis that the controller performs to determine core body temperature, feeding identification, device dislodgement etc.
Some embodiments of the gastric access device include the ability to place the device and/or feeding tube into the small intestine for feeding. This entails navigating the device past the pylorus. The controller of the device has the capability of identifying when the device is post pyloric vs. bending back on itself within the stomach. The controller of the device can analyze the signals from the sensors along the device and identify different signals or signatures for these two, and other, situations. For example, the description associated with
Note that the signatures may identify other events, in addition to the location of the device, including consumption of water, feeding events, reflux events, peristalsis, GRV, digestive speed, digestive health, device migration, device bending, device malfunction, etc.
Some embodiments of the gastric access device may monitor core body temperature and eliminate the need for an esophageal temperature probe. The temperature sensed by standard esophageal temperature probes may vary significantly depending on the placement location. The temperature may be affected by the temperature of the air in the lungs when the probe is proximal to the lungs. Gastric access devices disclosed herein may be placed more consistently, and deeper within the anatomy, to obtain more consistent and accurate core body temperature. The gastric access device controller may account for temperature affects from added formula by ignoring the sensed temperature during feeding events, or accounting for the effect on measured temperature by feeding events, to achieve true core body temperature. This correction may be achieved automatically, by pausing core temperature data collection during feeding, or accounting for temperature changes caused by feeding using a correction factor. Alternatively, this correction may be achieved by manually pausing the temperature sensing during feeding events. The core temperature may be measured using a temperature sensor which is just above, at, or just below the LES, to avoid impact on the reading by feeding events. The device may use signals from temperature sensors at more than one location along the device. The gastric access system may also have an internal temperature sensor to measure the temperature of the formula through the feeding tube to account for the formula's effect on the core body temperature.
In some embodiments of the gastric access device, the device can detect when the patient is swallowing. This may be done by the controller monitoring the propagation of the impedance signal from the more proximal sensors to the more distal sensors of the device. As the patient swallows, tissue comes in contact first with the more proximal sensors, and then propagates down to the more distal sensors. This tissue contact changes the impedance, and the propagation of the signals through the sensors can be identified as a signature signal which represents swallowing. This signature can be used to monitor swallowing during placement of the device, or after the device is placed. For example, in some instances a patient is asked to sip water during placement. Monitoring whether the device is detecting patient swallowing can help determine whether the device is placed correctly. It can also assess patient swallowing health.
Whether a patient is awake or unconscious may affect the movement of the gastric access device in the esophagus and stomach during placement, or after it is in place. When the patient is awake, the device may move more within the esophagus and as a result, temperature readings may fluctuate more than within an unconscious patient. In embodiments which are collecting temperature readings to detect breathing fluctuations and therefor whether the device has migrated nearer to the lungs, the threshold for displacement may be different for conscious and unconscious patients. For example, the range of acceptable or “not migrated” temperature fluctuations may be greater in conscious patients than it is in unconscious patients.
In some embodiments, the angle or position of the patient may be considered, or dictated, to obtain the most accurate measurements of GRV. For example, the head angle may be entered into, or sensed by, the system to take the patient angle into account. In some embodiments, the patient is put into the left lateral incumbent position, or other position, to get more accurate or reference readings.
In some embodiments, external electrodes (on the skin surface of the abdomen) may be used in conjunction with electrodes on the gastric access device inside the digestive system monitor and assess gastric contractions.
Any of the embodiments of the gastric access device disclosed herein may be incorporated into a stylet, or guidewire, instead of, or in addition to, into a feeding tube. A stylet or guidewire may be used through a lumen of a feeding tube, including the feeding lumen or a different lumen, or may be used along side a feeding tube. In embodiments where a stylet is used along side a feeding tube, the feeding tube may include an external guide, or guides, along the length of the feeding tube. For example, the feeding tube may have a loop or ring near the distal tip, to hold the guidewire/stylet near the distal tip of the feeding tube during placement. This is similar to a “rapid exchange” design used with angioplasty catheters and guidewires.
Any of the embodiments disclosed herein may be used in other applications, for example, any application where a body cavity is accessed. For example, the technology may be applied to vascular catheters, urinary catheters, heart catheters, other catheters, peritoneal access devices, endotracheal tubes, endotracheal access devices, etc.
Any of the features in any of the embodiments disclosed herein may be combined with any of the other features and may be used in any of the embodiments disclosed herein.
As shown in
Typically, the input/output devices 3310 are coupled to the system through input/output controllers 3309. The volatile RAM 3305 is typically implemented as dynamic RAM (DRAM) which requires power continuously in order to refresh or maintain the data in the memory. The non-volatile memory 3306 is typically a magnetic hard drive, a magnetic optical drive, an optical drive, or a DVD RAM or other type of memory system which maintains data even after power is removed from the system. Typically, the non-volatile memory will also be a random access memory, although this is not required.
While
Some portions of the preceding detailed descriptions have been presented in terms of algorithms and symbolic representations of operations on data bits within a computer memory. These algorithmic descriptions and representations are the ways used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. An algorithm is here, and generally, conceived to be a self-consistent sequence of operations leading to a desired result. The operations are those requiring physical manipulations of physical quantities.
It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the above discussion, it is appreciated that throughout the description, discussions utilizing terms such as those set forth in the claims below, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system's registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices.
The techniques shown in the figures can be implemented using code and data stored and executed on one or more electronic devices. Such electronic devices store and communicate (internally and/or with other electronic devices over a network) code and data using computer-readable media, such as non-transitory computer-readable storage media (e.g., magnetic disks; optical disks; random access memory; read only memory; flash memory devices; phase-change memory) and transitory computer-readable transmission media (e.g., electrical, optical, acoustical or other form of propagated signals-such as carrier waves, infrared signals, digital signals).
The processes or methods depicted in the preceding figures may be performed by processing logic that comprises hardware (e.g. circuitry, dedicated logic, etc.), firmware, software (e.g., embodied on a non-transitory computer readable medium), or a combination of both. Although the processes or methods are described above in terms of some sequential operations, it should be appreciated that some of the operations described may be performed in a different order. Moreover, some operations may be performed in parallel rather than sequentially.
All embodiments disclosed herein may incorporate features from other embodiments disclosed herein.
This application is a continuation of PCT/US2022/078105 filed Oct. 14, 2022, which claims the benefit of priority to U.S. Provisional Application No. 63/256,834 filed Oct. 18, 2021, each of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 63256834 | Oct 2021 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2022/078105 | Oct 2022 | WO |
| Child | 18626872 | US |
