Patent Publication Number: US-2020297238-A1

Title: Apparatuses and methods for assisting, confirming, and monitoring placement of catheters in patients

Description:
RELATED APPLICATION DATA 
     This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/821,964 filed on Mar. 21, 2019, pending. The entire disclosure of the above application is expressly incorporated by reference herein. 
    
    
     FIELD 
     One or more embodiments described herein relate to medical devices and methods for monitoring catheters, and more specifically to medical devices and associated methods for assisting, confirming, and monitoring placement of catheters in patients using ECG tracings. 
     BACKGROUND 
     Umbilical venous catheters (UVC) are routinely inserted during the treatment of ill neonates for the administration of fluids and medication, as well as for central venous pressure monitoring. The catheters are inserted and blindly advanced from the umbilicus into the thorax. The optimal location for the tip of the venous catheter is in the inferior vena cava (IVC) or at the junction of the IVC and the right atrium (RA). The reported incidence of misplaced umbilical venous or arterial catheters is in the range of 2037%. If the tip is placed too high in the RA, there is an increased risk of myocardial infiltration and arrhythmias. If the tip is placed too low in the IVC, there may be a risk of either intrahepatic or extrahepatic placement into the portal vessels resulting in complications such as portal vein thrombosis, portal hypertension, and liver necrosis. Although radiographs are routinely used to confirm the proper positioning of umbilical arterial or venous catheters, this technique requires the movement of infants as well as radiation exposure to infants who are often critically ill. Therefore, an easy, reliable, and real-time guidance and confirmation technique for UVC placement would be beneficial. More importantly, studies have demonstrated that 50% of UVCs in infants born less than 32 weeks gestation migrated within the first week after insertion. Thus, it is critical to monitor the location of umbilical catheters. 
     SUMMARY 
     A medical method performed by a medical device, includes: generating a ECG tracing using a first electrode placed on a surface of a patient and a second electrode at a catheter inside the patient; and outputting the ECG tracing for presentation to a user; wherein the first electrode is fixed in position with respect to the patient; and wherein an amplitude of the ECG tracing corresponds with a relative distance between the first electrode and the second electrode. 
     Optionally, the catheter comprises an umbilical venous catheter. 
     Optionally, the patient comprises a pediatric patient. 
     Optionally, the amplitude of the ECG tracing is equal to zero or has a minimum value when the second electrode is directly beneath the first electrode. 
     Optionally, the ECG tracing is outputted for display on a screen. 
     Optionally, the first electrode is located above a target position for the second electrode. 
     Optionally, the method further includes generating an audio signal when the second electrode is underneath the first electrode. 
     Optionally, the method further includes repeating the act of generating and the act of outputting while the catheter is being positioned inside the patient. 
     Optionally, the repeating is performed to provide a real-time indication of a position of the catheter with respect to the first electrode. 
     Optionally, the method further includes repeating the act of generating and the act of outputting after the catheter has been placed at a target position inside the patient. 
     Optionally, the repeating is performed to allow monitoring of the placed catheter at the target position. 
     Optionally, the method further includes generating an audio signal when the catheter is displaced from the target position. 
     A medical device includes: a first electrode configured for placement on a surface of a patient; a second electrode configured for coupling with a catheter; and a processing unit configured to generate a ECG tracing using the first electrode on the surface of the patient and the second electrode inside the patient. 
     Optionally, the medical device further includes a screen for displaying the ECG tracing. 
     Optionally, the processing unit is a part of a ECG device. 
     Optionally, the catheter comprises an umbilical venous catheter, and the second electrode is configured for coupling with the umbilical venous catheter. 
     Optionally, the processing unit is configured to generate the ECG tracing with an amplitude that is equal to zero or has a minimum value when the second electrode is directly beneath the first electrode. 
     Optionally, the medical device further includes a screen, wherein the processing unit is configured to output the ECG tracing for display on the screen. 
     Optionally, the first electrode is configured for placement above a target position for the second electrode. 
     Optionally, the medical device further includes a speaker configured to provide an audio signal when the second electrode is underneath the first electrode. 
     Optionally, the processing unit is configured to generate additional ECG tracing(s) while the catheter is being positioned inside the patient. 
     Optionally, the additional ECG tracing(s) provides a real-time indication of a position of the catheter with respect to the first electrode. 
     Optionally, the processing unit is configured to generate additional ECG tracing(s) after the catheter has been placed at a target position inside the patient. 
     Optionally, the additional ECG tracing(s) provides monitoring of the placed catheter at the target position. 
     Optionally, the medical device further includes a speaker configured to provide an audio signal when the catheter is displaced from the target position. 
     Optionally, the first electrode is on a pad with an adhesive surface and a plurality of markers. 
     Optionally, first electrode is located on the pad in association with one of the markers. 
     Optionally, the markers are in a single row. 
     Optionally, the markers are arranged in rows and columns. 
     A medical device includes: a pad having an adhesive surface; a plurality of markers at the pad; and an external electrode in positional correspondence with a selected one of the markers, wherein the external electrode is configured to couple with a lead extending from an apparatus, the apparatus having a processing unit. 
     Optionally, the markers are in a single row. 
     Optionally, the markers are arranged in rows and columns. 
     Optionally, the medical device further includes a catheter electrode configured to couple with another lead extending from the apparatus. 
     Optionally, the medical device further includes the apparatus. 
     Optionally, the apparatus comprises a ECG device. 
     A medical device includes: a pad having an adhesive surface; a plurality of electrodes coupled to the pad; and a plurality of terminals respectively at, or electrically connected to, the plurality of electrodes; wherein each of the terminals in the plurality of terminals is capable of being detachably coupled to a lead extending from an apparatus, the apparatus having a processing unit. 
     Optionally, the electrodes in the plurality of electrodes are in a single row. 
     Optionally, the electrodes in the plurality of electrodes are arranged in rows and columns. 
     Optionally, the medical device further includes a catheter electrode configured to couple with another lead extending from the apparatus. 
     Optionally, the medical device further includes the apparatus. 
     Optionally, the apparatus comprises a ECG device. 
     Optionally, the electrodes are radiopaque. 
     Optionally, the electrodes are coupled to respective markers. 
     A medical method includes: placing a pad on a surface of a patient, the pad having a plurality of markers; taking an image of the patient, the image indicating an internal anatomical structure of the patient and the plurality of markers; coupling an electrode with an apparatus via a lead, wherein the electrode is in positional correspondence with one of the plurality of markers that is the closest in position with respect to the internal anatomical structure of the patient as they appear in the image. 
     Optionally, the markers are in a single row. 
     Optionally, the markers are arranged in rows and columns. 
     Optionally, the apparatus comprises a ECG device. 
     Optionally, the method further includes using the apparatus to monitor a position of a catheter while the catheter is being positioned within the patient. 
     Optionally, the catheter comprises an umbilical venous catheter. 
     Optionally, the patient comprises a pediatric patient. 
     Other aspects, embodiments, and benefits will be described in the detailed description below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages will become readily apparent to those skilled in the art by the following detailed description of exemplary embodiments thereof with reference to the attached drawings, in which: 
         FIG. 1  shows different ECG tracings for different anatomical structures. 
         FIG. 2A  shows an example of a medical device. 
         FIG. 2B  shows definition of bio-potential channels utilized in the medical device of  FIG. 2A . 
         FIG. 2C  shows a neonate with an external electrode (patch electrode) in place, wherein the external electrode is at a pad with adhesive, and a plurality of markers. 
         FIG. 2D  shows an example of a radiograph with the radio-opaque markers and various components of a medical device in their respective operative positions. 
         FIG. 3A  illustrates placement of electrodes in standard ECG. 
         FIG. 3B  illustrates placement of electrodes in accordance with some embodiments. 
         FIGS. 4A-4D  illustrates surface mapping in a patient and operation of the medical device of  FIG. 2A . 
         FIG. 5  illustrates placement of device at lower abdomen of a patient. 
         FIG. 6  is a block diagram illustrating an embodiment of a specialized processing system. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments are described hereinafter with reference to the figures. Like reference numerals refer to like elements throughout. Like elements will, thus, not be described in detail with respect to the description of each figure. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the claimed invention or as a limitation on the scope of the claimed invention. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described. 
     This disclosure describes devices and methods that provide an easy, reliable, and real-time confirmation technique to verify UVC placement, or placement of other catheters or medical devices, in patients. 
     Electrocardiogram (ECG) may be used to guide the placement of UVC catheter (CVC) via a saline column.  FIG. 1  shows different ECG tracings for different anatomical structures, such as spleen, liver, inferior vena cava, atrium, etc. Although the ECG method is able to avoid grossly misplacing catheters, small changes can be challenging to detect in some cases. 
     In some embodiments described herein, a medical device is provided that is able to improve on the guidance, detect small changes, and monitor catheter migration through reference to a target surface electrode, e.g., Target Surface UVC Indicator (TSUI) electrode. 
       FIG. 2A  shows an example of a medical device  100 . The medical device  100  includes ports  110  with respective leads  120   a - 120   c  connecting to respective electrodes  130   a - 130   c . In some embodiments, the ports  110  may be ECG ports. The first electrode  130   a  is a patch electrode (PE) configured for placement on a skin of a patient. The second electrode  130   b  is a catheter electrode (ICE) configured to be carried by a catheter  132 , such as an UVC. The third electrode  130   c  (LL) is configured for placement at a patient&#39;s lower chest or leg. In other embodiments, the second electrode  130   b  may be configured to be carried by other types of medical devices that are not catheter. For example, in other embodiments, the second electrode  130   b  may be carried by an implant being delivered, a guidewire, etc. Also, in other embodiments, the third electrode  130   c  may be configured for placement at other locations that are not the lower chest or leg. 
     The first electrode  130   a  may be any electrode that is configured for placement on a patient. Similarly, the third electrode  130   c  may be any electrode that is configured for placement on the patient. 
     In some embodiments, the second electrode  130   b  may be an electrode secured to a part of the catheter  132 . In other embodiments, the second electrode  130   b  may be an electrode on a separate device that is inserted into the catheter  132 . In further embodiments, the catheter tip may be transformed into an electrode. In one specific implementation, prior to the insertion of the catheter  132  into a patient, a conductive Johans ECG adapter may be connected to a distal port of a 3 or 5 French (single or triple lumen) UVC. The catheter  132  may be primed with 0.9% normal saline to ensure an air-free column of fluid from the ECG connector to the catheter tip. This will transform the UVC catheter tip into a unipolar ECG electrode. 
     The medical device  100  also includes a processing unit  140 . The processing unit  140  is configured to receive signals from the leads  120   a - 120   c , and process the signals to generate graphic for display by a monitor  150 . In the illustrated embodiments, the graphic are waveforms generated based on signals from the electrodes  130   a - 130   c  and/or based on channels defined among the electrodes  130   a - 130   c . Examples of channels defined among the electrodes  130   a - 130   c  will be described with reference to  FIG. 2B . In other embodiments, the graphic may have other configurations. For example, in other embodiments, the graphic may include a numerical value representing a distance between two electrodes (e.g., electrodes  130   a ,  130   b ) and/or a distance between the electrode  130   b  and a target location. 
     The processing unit  140  may be implemented using hardware, software, or a combination of both. In some embodiments, the hardware for implementing the processing unit  140  may include a processor, such as a general purpose processor, a microprocessor, a FPGA processor, an ASIC processor, or any of other types of processors. Also, in some embodiments, the hardware for implementing the processing unit  140  may include an integrated circuit. The processing unit  140  may include one or more processors and/or one or more modules in some embodiments. In some embodiments, the processing unit  140  may include an analysis and control unit. Also, in some embodiments, the processing unit  140  is configured to process signals from the electrodes  130   a ,  130   b ,  130   c , and to interpret the signals. In addition, in some embodiments, the processing unit  140  may also be configured to generate output indicating a position of a catheter tip of the catheter  132 . 
     Referring to  FIG. 2A , the medical device  100  also includes a relay  160  coupled to the lead  120   a . The relay  160  is configured to communicate with the processing unit  140  during use. The relay  160  will be described in further detail. 
       FIG. 2B  shows definition of bio-potential channels (arrow points from + to 1) for the medical device  100 . Channel A is defined as a channel between the first electrode  130   a  (e.g., PE) and the third electrode  130   c  (e.g., LL). Channel B is defined as a channel between the second electrode  130   b  (e.g., ICE) and the third electrode  130   c  (e.g., LL). Channel C is defined as a channel between the first electrode  130   a  (PE) and the second electrode  130   b  (e.g., ICE). In other embodiments, the direction for any of the above examples of channels may be opposite. Also, in other embodiments, the device  10  may not include all three channels A, B, C. For example, the device  10  may not include the channel A and/or the channel B in some embodiments. 
       FIGS. 2C-2D  show an example of an electrode device  200  for implementing the first electrode  130   a  (patch electrode). The electrode device  200  is illustrated as being placed in position with respect to a neonate. In the illustrated embodiments, the electrode device  200  includes a pad  202  with adhesive for detachably coupling to a skin of the patient. The electrode device  200  also includes a plurality of markers  210 , and a plurality of electrodes  250  (shown in  FIG. 2D ). One of the electrodes  250  may be selected to function as the first electrode  130   a . As shown in  FIG. 2C , the electrode device  200  is coupled to the relay  160 . The relay controller  160  is an interface between the electrodes  250  and the processing unit  140 . The relay controller  160  is configured to define, based on user input, which one of the electrodes  250  of the electrode device  200  is to be connected to the processing unit  140  of the medical device  100  at any given time without impeding other physiological measurements. In other embodiments, the relay controller  160  may be implemented on the pad  202  or at the processing unit  140 . 
     As shown in  FIG. 2C , the electrode device  200  also includes a series of LEDs  252  for visual feedback. In some embodiments, the LEDs  252  are configured to inform a user of the device  100  regarding a position of the catheter  132  inside the patient with respect to a target region in the patient. In one implementation, the LEDs  252  are arranged in a row, with a center one of the LEDs  252  representing a desired position of the end of the catheter  132  with respect to a target region in the patient. In such cases, when the end of the catheter  132  is at a desired position in the patient, the center LED  252  (e.g., first LED) will be on. When the end of the catheter  132  move slightly away from the desired position in one direction (e.g., a first direction), then the center LED  252  will be off, and another LED  252  (e.g., a second LED) adjacent to the center LED  252  will be on. If the end of the catheter  132  move further away from the desired position in the same direction, then the second LED will be off, and the adjacent LED (e.g., a third LED) will be on. On the other hand, when the end of the catheter  132  move slightly away from the desired position in another direction (e.g., a second direction opposite from the first direction), then the center LED  252  will be off, and another LED  252  (e.g., a fourth LED) adjacent to the center LED  252  will be on. If the end of the catheter  132  move further away from the desired position in the same direction (e.g., second direction), then the fourth LED will be off, and the adjacent LED (e.g., a fifth LED) will be on. In some embodiments, the processing unit  140  is configured to process signals from the electrodes  130 , and to generate a control signal to cause one of the LEDs  252  to illuminate. For example, the processing unit  140  may be configured to analyze waveform in Channel C, and to determine a distance between the first electrode  130   a  and the second electrode  130   b  based on the waveform in Channel C. The processing unit  140  may be configured to generate a control signal to cause a corresponding LED  252  to illuminate based on the determined distance. In some embodiments, the medical device  100  may include the LEDs  252 , but not the monitor  150 , because the LEDs  252  already are capable of informing a user regarding a position of the catheter  132 . In other embodiments, the medical device  100  may include both the monitor  150  and the LEDs  252 . In further embodiments, the medical device  100  may not include the LEDs  252 . 
     In some embodiments, after the electrode device  200  with the electrodes  250  have been attached to the patient, an imaging (e.g., x-ray imaging) may be performed for the patient to obtain an image. The image may indicate anatomical structure(s) in the patient as well as markers  210  associated with the electrodes  250 . In the illustrated example, because the electrodes  250  are aligned next to the markers  210 , as shown in  FIG. 2C , the positions of the markers  210  may be utilized to indicate, and/or may associate with corresponding electrodes  250 . Accordingly, the markers  210  may allow a user to determine an optimal placement position of the catheter  132  to be placed inside the patient. In particular, from the markers  210  captured in the image, the user may then determine which electrode  250  is closest in proximity to a desired target position for the catheter tip (to be inserted and placed inside the patient). The selected one of the electrodes  250  of the electrode device  200  may then function as the first electrode  130   a  (e.g., TSUI electrode) may then be connected to the processing unit  140  of the device  100  (e.g., via the relay controller  160 ). After that, a catheter  132  may then be inserted into the patient. The catheter  132  has a catheter electrode  130   b  (which may be placed at the tip of the catheter), which is also coupled to an input of the device  100 . The device  100  with the first electrode  130   a  and second electrode  130   b  (e.g., catheter electrode) may then be used to determine positions and placement of the catheter  132 . 
     In some embodiments, the selection of which of the electrodes  250  on the electrode device  200  to function as the first electrode  130   a  may be achieved via a user interface at the device  100  that operates the relay controller  160 . For example, if the electrode device  200  has six electrodes  250 , and electrode  250  number 4 is selected as the one to use as the first electrode  130   a  (e.g., based on a user viewing an imaging showing the positions of the electrodes  250  with respect to a patient&#39;s anatomy), the user may operate the user interface to cause the relay controller  160  to communicatively connect electrode number 4 with the processing unit  140  of the medical device  100 . The user interface may be a keyboard, a touch screen, one or more buttons, one or more switches, etc. The user interface may be located at, or may be communicatively coupled to, the electrode device  200 , to the relay  160 , to the processing unit  140 , or any combination of the foregoing. 
       FIG. 2D  shows an example of a radiograph illustrating the electrode device  200  coupled to the patient. The radio-opaque markers  210  and the electrodes  250  are visible in the image. The image also shows the third electrode  130   c  coupled to the patient, and the catheter  132  inserted inside the patient. 
     In the above embodiments, the electrode device  200  includes both the markers  210  and the electrodes  250 . In other embodiments, the electrodes  250  themselves may be radiopaque (in which case, the electrode device  200  may not include the markers  210 ). In one implementation, parts of the electrodes  250  may be made from an radio-opaque material. In another implementation, a radio-opaque marker may be attached to each of the electrodes  250 . 
     In further embodiments, a marker device (without any electrode) may be utilized to determine a desired position for placement of the first electrode  130   a . For example, the marker device may include a patch for securement against a patient, and a plurality of markers. The markers may be radio-opaque markers. During use, the markers of the marker device are imaged to determine which of the markers is closest in position with respect to the target position for the catheter tip. After a marker has been selected, the first electrode  130   a  may then be placed on the patient in association with the selected marker. For example, the first electrode  130   a  may be placed next to the selected marker, or at the same location as the selected marker. In such embodiments, the device  100  does not include the relay controller  160 , and the first electrode  130   a  may be implemented without using the electrode device  200  having multiple electrodes  250 . For example, in such cases, the first electrode  130   a  may be a single electrode implemented on a patch for detachably coupling to a patient. 
       FIG. 3A  illustrates placement of electrodes in standard ECG setup. As shown in the figure, in a standard ECG setup, a first electrode  300   a  is placed at a right arm, a second electrode  300   b  is placed at the left arm, and a third electrode  300   c  is placed at the lower chest or leg. 
       FIG. 3B  illustrates placement of the electrodes  130   a - 130   c  of the device  100  in accordance with some embodiments. As shown in the figure, the first electrode  130   a  (the exterior surface electrode) is placed at a chest of a patient, the second electrode  130   b  is at a catheter, and the third electrode  130   c  is placed at the lower chest or leg. 
       FIGS. 4A-4D  below illustrates surface mapping in a patient and operation of the medical device  100 . The recorded signals are interpreted by the processing unit  140 , which generates graphic visualizing the interpreted signals. The graphic is displayed by the monitor  150 . In the illustrated example, the graphic includes three waveforms corresponding to the three respective channels defined among the electrodes  130   a - 130   c . The first electrode  130   a  is placed at the midline 1 cm below the intermammary line (nipple line). In some embodiments, the first electrode  130   a  may be a surface electrode implemented by modifying a lead of a cardiac monitoring device. The second electrode  130   b  is coupled to the catheter  132 . In some embodiments, the second electrode  130   b  may be manufactured with the catheter  132 . In other embodiments, the second electrode  130   b  may be attached to the catheter  132  after the catheter  132  is manufactured. Also, in some embodiments, the second electrode  130   b  may be connected to the catheter line (e.g., UVC line) via an adapter. For example, a lead functioning as the second electrode  130   b  may be connected to the UVC line via a Johans adapter or similar adapter. The third electrode  130   c  is placed on the left leg or left mid axillary line below the heart. Channel A displays Lead II where the waveform represents the difference between the first electrode  130   a  and the third electrode  130   c . Channel B displays Lead III where the waveform represents the difference between the second electrode  130   b  (e.g., intracavitary electrode) and the third electrode  130   c . Channel C displays Lead I where the waveform represents the biopotential difference between the second electrode  130   b  (e.g., intracavitary electrode) and the first electrode  130   a . In the illustrated embodiments, a Channel C “flipping” method is used to identify the proximity and location of the catheter tip relative to a specific target surface electrode. 
       FIGS. 4A-4D  illustrates the catheter  132  of the device  100 , and a process for positioning the tip of the catheter  132 . In the illustrated example, the catheter  132  is inserted from an umbilical insertion site, and is advanced to reach an IVC within the thoracic region. In other embodiments, the catheter  132  may be other types of catheter, and may be inserted from other sites and/or may be advanced to reach different regions in the patient. 
     As shown in  FIG. 4A , while the catheter  132  with the catheter electrode  130   b  is at the lower abdominal inside the patient, the ECG trace in Channel C will have a relatively high amplitude due to the long distance with respect to the first electrode  130   a  (external or surface electrode). Also, the ECG trace in Channel B will have a relatively low amplitude (e.g., zero amplitude) due to the relatively close distance with respect to the third electrode  130   c  placed at the lower abdomen or leg. 
     As the catheter  132  is being moved up inside the patient, the ECG traces in Channel B and Channel C change. As shown in  FIG. 4B , the ECG trace in Channel C reduces in amplitude due to the second electrode  130   b  (the catheter electrode) being moved closer towards the first electrode  130   a . At the same time, the ECG trace in Channel B increases in amplitude due to the second electrode  130   b  (the catheter electrode) being moved further from the third electrode  130   c  at the lower abdomen or leg. 
     As shown in  FIG. 4C , when the catheter  132  is placed directly beneath the first electrode  130   a  (i.e., at the target position), the ECG trace in Channel C has the lowest amplitude (e.g., zero amplitude), and the ECG trace in Channel B increases even further (compared to that in  FIG. 4B ). 
     As shown in  FIG. 4D , if the catheter  132  is accidentally moved further up so that it is away from the target position, the ECG trace in Channel C will have an increase in amplitude, and the ECG trace in Channel B will also have an increase in amplitude (compared to those in  FIG. 4C ). The ECG trace in Channel C has a sign that is “flipped” compared to that in  FIGS. 4A-4B . This is because the second electrode  130   b  has now moved from one side of the first electrode  130   a  to the opposite side of the first electrode  130   a . Accordingly, the ECG trace(s) from the device  100  may be used to assist positioning of the catheter  132  inside the patient. 
     As illustrated in the above embodiments, cardiac electrophysiology may be utilized to identify the location of electrodes in reference to each other using the heart as a natural “signal generator”. 
     In some embodiments, a user of the device  100  may decide that the catheter has been desirably placed by viewing the ECG trace in Channel C. In other embodiments, the device  100  may automatically detect that the catheter has been desirably placed based on the minimal amplitude of the ECG trace in Channel C. In such cases, the device  100  may provide a signal to inform the user. For example, the device  100  may provide an audio signal via a speaker, and/or a visual indicator (e.g., a LED indicator, a displayed graphic, etc.), to inform the user that the catheter has been placed at a desired position. In some embodiments, the processing unit  140  may be configured to determine that the catheter has been desirably placed by monitoring the amplitude of the waveform for Channel C (defined between the first and second electrodes  130   a ,  130   b ). If the waveform reaches a minimum amplitude, then the processing unit  140  may generate a signal to inform a user that the catheter has been desirably placed inside the patient. 
     After the initial positioning is completed, a radiograph may be acquired to visualize catheter placement in regard to internal anatomical landmarks to confirm that the catheter  132  has been desirably placed at the target position. In some cases, by observing radio-opaque markings (e.g., markers attached to the patient, such as those described with reference to  FIGS. 2C-2D ), the caregiver can perform any finer position adjustments if needed. 
     After the catheter  132  has been desirably positioned in the patient, and its position has been confirmed, the catheter  132  may then be fixed in position with respect to the patient. In some embodiments, the device  100  of  FIG. 2A  may also be used to monitor the placed catheter  132 , so that the device  100  can alarm a user if the catheter  132  is accidentally displaced. For example, if the ECG trace in Channel C has an increase in amplitude, then it indicates that the catheter  132  has been displaced. In such cases, the device  100  of  FIG. 2  may provide a signal to inform the user. For example, the device  100  may provide an audio signal via a speaker, and/or a visual indicator (e.g., a LED indicator, a displayed graphic, etc.). 
     In some embodiments, the processing unit  140  of the device  100  is configured to analyze Channel C to automatically and continuously determine a position of the second electrode  130   b  (e.g., catheter electrode) with respect to the first electrode  130   a  (e.g., surface electrode), during placement of the catheter  132  and/or after placement of the catheter  132  in the patient. 
     In some embodiments, the processing unit  140  may include an analysis unit configured to receive signals from the ports  110 . The analysis unit is configured to identify the level of the patch at which ECIF occurs and provide notifications and alerts regarding the location of the tip and in the event of tip migration. In some embodiments, the analysis unit is configured to determine a distance between the first and second electrodes  130   a ,  130   b , and generate a signal to indicate such distance. The analysis unit is configured to repeatedly determine the distance between the first and second electrodes  130   a ,  130   b , and to repeatedly generate the signal to indicate the distance, thereby providing real-time information to a user of the device  100  regarding a placement of the catheter  132  with respect to a target location inside the patient. 
     In some embodiments, a part of the medical device  100  described herein may be implemented using a ECG monitor. For example, the ECG monitor may display QRS complexes with P-waves. A small QRS indicates that the catheter is below the diaphragm and possibly in the liver or spleen. An inversion of the QRS axis is presumed to indicate that the tip has passed the beyond midline into the spleen. The appearance of a tall positive P-wave will indicate that the catheter tip is at the right atrium level. In the event of a tall positive P-wave, the UVC may then be withdrawn until the P-wave returned to normal size. 
     The medical devices and methods described herein provide continuous and reliable UVC placement assistance and/or UVC migration monitoring. The devices and methods can not only provide real-time guidance for optimal placement, but also can provide a 24/7 non-invasive monitoring of the position of catheters, such as UVC, umbilical artery catheter (UAC), etc. 
     As shown in the above embodiments, the channel C (defined between electrodes  130   a ,  130   b ) provides distinct signal changes to indicate whether the catheter  132  carrying the second electrode  130   b  is below (positive deflection), above (flip to negative deflection), and at the same level of the first electrode  130   a  (zero deflection), such as those shown in  FIGS. 4A-4D . These features allow for simple, reliable, and real-time location detection as well as the ability to monitor placement and position of catheter  132  using an alarm. The use of the Channel C “flipping” method to identify the proximity and location of the catheter tip relative to a specific target surface is believed to be novel and inventive. 
     It should be noted that the device  100  and technique described herein are not limited to determining positions of internal electrode along the path shown in  FIGS. 4A-4D . In other embodiments, the device  100  and technique described herein may be applied to determine and/or monitor position of internal electrode at other locations in a human body.  FIG. 5  illustrates the catheter  132  with the second electrode  130   b  placed at lower abdomen (e.g., at or near a liver) inside a patient. The signals between the various channels are displayed by the monitor  150  for visualization by a user. 
     The devices and methods described herein are advantageous because they allow catheter placement to become a straightforward and accurate process that requires only a single radiograph. The ECG tracings will also enable a user to monitor UVC catheter placement more closely, thereby potentially reducing risks associated with the procedure. 
     The devices and methods described herein are not limited to monitoring UVC placement and positions, and may be applied for other types of catheters (e.g., any catheter type: brand, number of lumens, or diameter), or other objects for placement inside anywhere in a patient&#39;s body. 
     In other embodiments, instead of umbilical venous catheters, the device  100  and technique described herein may be utilized to determine and/or monitor positions of other types of catheters inside patients. For examples, in other embodiments, the device  100  and technique described herein may be utilized to determine and/or monitor positions of biopsy catheters, diagnostic catheters (e.g., catheters with imaging capability), implant delivery catheters, treatment catheters, drug delivery catheters, etc. 
     Also, in other embodiments, instead of catheters, the device  100  and technique described herein may be utilized to determine and/or monitor positions of other types of medical devices inside patients. For example, in other embodiments, the device  100  and technique described herein may be utilized to determine and/or monitor positions of implants, surgical tools, diagnostic devices, treatment devices, etc., placed inside patients. 
     Furthermore, in other embodiments, the medical device  100  is not limited to having all of the components shown in  FIG. 2A , and may have only a subset of the components shown in  FIG. 2A . For example, in other embodiments, the medical device  100  may include only the first electrode  130   a , the lead  120   a , and the relay  160 . In further embodiments, the medical device  100  may include only the electrode device  200  shown in  FIG. 2C . In other embodiments, the medical device  100  may include only the processing unit  140 . The processing unit  140  may include a signal interpreter for interpreting signals from the electrodes  130   a - 130   c , an analyzer for analyzing the signals to determine a position of the second electrode  130   b  with respect to the first electrode  130   a . In still further embodiments, the medical device  100  may include the first electrode  130   a  (which may be implemented using the electrode device  200 ), the second electrode  130   b , the third electrode  130   c , the relay  160 , the processing unit  140 , or any combination of the foregoing. 
     In addition, in some embodiments, at least a part of the medical device  100  may be implemented using a NICU monitor. 
     Also, in further embodiments, the device  100  may not include the third electrode  103   c  and the third lead  120   c . In such cases, the device  100  may not include the channel A and the channel B. 
       FIG. 6  is a block diagram illustrating an embodiment of a specialized processing system  1600  that can be used to implement various embodiments described herein. For example, the processing system  1600  may be configured to implement the device  100 , or one or more components of the device  100 , in accordance with some embodiments. For example, in some embodiments, the processing system  1600  may be used to implement the processing unit  140 . The processing system  1600  may also be an example of any processor described herein. 
     Processing system  1600  includes a bus  1602  or other communication mechanism for communicating information, and a processor  1604  coupled with the bus  1602  for processing information. The processor system  1600  also includes a main memory  1606 , such as a random access memory (RAM) or other dynamic storage device, coupled to the bus  1602  for storing information and instructions to be executed by the processor  1604 . The main memory  1606  also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by the processor  1604 . The processor system  1600  further includes a read only memory (ROM)  1608  or other static storage device coupled to the bus  1602  for storing static information and instructions for the processor  1604 . A data storage device  1610 , such as a magnetic disk or optical disk, is provided and coupled to the bus  1602  for storing information and instructions. 
     The processor system  1600  may be coupled via the bus  1602  to a display  167 , such as a flat panel, for displaying information to a user. An input device  1614 , including alphanumeric and other keys, is coupled to the bus  1602  for communicating information and command selections to processor  1604 . Another type of user input device is cursor control  1616 , such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor  1604  and for controlling cursor movement on display  167 . This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allows the device to specify positions in a plane. 
     In some embodiments, the processor system  1600  can be used to perform various functions described herein. According to some embodiments, such use is provided by processor system  1600  in response to processor  1604  executing one or more sequences of one or more instructions contained in the main memory  1606 . Those skilled in the art will know how to prepare such instructions based on the functions and methods described herein. Such instructions may be read into the main memory  1606  from another processor-readable medium, such as storage device  1610 . Execution of the sequences of instructions contained in the main memory  1606  causes the processor  1604  to perform the process steps described herein. One or more processors in a multi-processing arrangement may also be employed to execute the sequences of instructions contained in the main memory  1606 . In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the various embodiments described herein. Thus, embodiments are not limited to any specific combination of hardware circuitry and software. 
     The term “processor-readable medium” as used herein refers to any medium that participates in providing instructions to the processor  1604  for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks, such as the storage device  1610 . A non-volatile medium may be considered an example of non-transitory medium. Volatile media includes dynamic memory, such as the main memory  1606 . A volatile medium may be considered an example of non-transitory medium. Transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise the bus  1602 . Transmission media can also take the form of acoustic or light waves, such as those generated during radio wave and infrared data communications. 
     Common forms of processor-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a processor can read. 
     Various forms of processor-readable media may be involved in carrying one or more sequences of one or more instructions to the processor  1604  for execution. For example, instructions may be stored in a portable storage device, such as a USB or a memory disk. The storage device may be detachably coupled to the processing system  1600  for transferring the instructions to the processing system  1600 . As another example, the instructions may be stored in a “cloud”. In such cases, the instructions may be downloaded from a server to the processing system  1600 . As another example, the instructions may initially be carried on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a network, such as a wireless network a telephone line, etc. A communication device, such as a network interface or a modem, local to the processing system  1600  can receive the data on the network, and provide the data on the bus  1602 . The bus  1602  carries the data to the main memory  1606 , from which the processor  1604  retrieves and executes the instructions. The instructions received by the main memory  1606  may optionally be stored on the storage device  1610  either before or after execution by the processor  1604 . 
     The processing system  1600  also includes a communication interface  1618  coupled to the bus  1602 . The communication interface  1618  provides a two-way data communication coupling to a network link  1620  that is connected to a local network  1622 . For example, the communication interface  1618  may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, the communication interface  1618  may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. Wireless links may also be implemented. In any such implementation, the communication interface  1618  sends and receives electrical, electromagnetic or optical signals that carry data streams representing various types of information. 
     The network link  1620  typically provides data communication through one or more networks to other devices. For example, the network link  1620  may provide a connection through local network  1622  to a host computer  1624  or to equipment  1626 . The data streams transported over the network link  1620  can comprise electrical, electromagnetic or optical signals. The signals through the various networks and the signals on the network link  1620  and through the communication interface  1618 , which carry data to and from the processing system  1600 , are exemplary forms of carrier waves transporting the information. The processing system  1600  can send messages and receive data, including program code, through the network(s), the network link  1620 , and the communication interface  1618 . 
     Although particular features have been shown and described, it will be understood that they are not intended to limit the claimed invention, and it will be made obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the claimed invention. The specification and drawings are, accordingly to be regarded in an illustrative rather than restrictive sense. The claimed invention is intended to cover all alternatives, modifications and equivalents.