Abstract:
A new device and method are introduced herein to facilitate vascular access in general and the placement of central venous access devices in particular. In one embodiment, the device consists of the following components: a wireless ultrasound imaging handheld scanner, a Bluetooth ECG (electrocardiography) data acquisition module with patient ECG cable and sterile adaptor, and a mobile medical application running on a mobile platform (device), e.g., a tablet, smartphone or smart watch. Ultrasound imaging and/or ECG-based catheter guidance provided by the device disclosed herein can be used to independently or simultaneously visualize the catheter in the vasculature and/or guide its placement at the desired location. In another embodiment of the present invention, ultrasound imaging of the blood vessel targeted for vascular access can be used for assessing the blood vessel size prior to cannulating the blood vessel, for guiding an access needle into the targeted blood vessel, and for visualizing the catheter in the vasculature after the introduction of the catheter. In another embodiment of the present invention, ECG-based navigation of an intravascular catheter can be used for tracking such intravascular catheter in the vasculature and positioning such intravascular catheter at a desired location. In one aspect of the present invention, the ultrasound imaging handheld scanner contains all the electronics required to acquire and process ultrasound images and to transfer them wirelessly to a mobile platform device, e.g., a tablet or a smartphone. In another aspect of the present invention, the ECG data acquisition module contains all the electronics required to acquire and process tracking and positioning information for ECG-based catheter guidance and to transfer such information wirelessly to a mobile platform device, e.g., a tablet or a smartphone. In another aspect of the present invention, algorithms are introduced for processing and synchronization of ultrasound images and ECG signals. In another aspect of the present invention, user interfaces for the handheld ultrasound imaging scanner, the ECG data acquisition module, and the mobile medical application running on a mobile platform are introduced in order to simplify the use of ultrasound imaging and/or ECG-based guidance for catheter placement on mobile platforms. In another aspect of the present invention, a new vascular access method is introduced using simultaneous ultrasound imaging and ECG-based catheter guidance. According to the present invention, using ultrasound imaging of a catheter in the vasculature simultaneously with detecting ECG signals at the tip of the catheter provide accurate and reliable catheter location information in adult and pediatric population for most of patients conditions and clinical environments.

Description:
[0001]    This application claims priority to U.S. Provisional Patent Application No. 62/104,895 filed on Jan. 19, 2015, the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to the field of vascular access, in particular to the placement of vascular access devices, e.g., peripherally and centrally inserted central catheters, implantable ports, etc. Currently, ultrasound imaging is used to guide venipuncture and the insertion of a catheter in a vein and ECG-based guidance is used to confirm the tip location of the catheter at the cavo-atrial junction. Electromagnetic tracking, Doppler and ECG are used to track (navigate) the intravascular catheter from the insertion point towards the cavo-atrial junction and chest X-rays, ECG, and fluoroscopy are used to place the catheter tip at the cavo-atrial junction. Transcutaneous ultrasound imaging is currently used to visualize the catheter in the vasculature after insertion and to check if the catheter has accidentally moved to an undesired location wherever ultrasound imaging is available at that location. Transesophageal ultrasound imaging can also be used to accurately place the catheter tip at the cavo-atrial junction. The purpose of the present invention is to provide a single easy-to-use, wireless device which combines ultrasound imaging and ECG-based tracking in order to guide a needle and a catheter for vascular access and to help position the catheter at the desired location in the vasculature. 
       BACKGROUND OF THE INVENTION 
     Clinical Need 
       [0003]    Vascular access is an important element of any minimally invasive clinical procedure and of clinical procedures needing access to the central venous system, e.g., chemotherapy, parenteral nutrition, etc. The access of the patient&#39;s vasculatures involves gaining access to the vasculature through an insertion or access point, inserting a catheter into the vasculature (cannulation) and advancing the catheter through the vasculature to the desired end location of the catheter tip. In different clinical situations the desired location of the catheter tip may be different for each of the situations. Due to the patient&#39;s anatomy, the catheter may not always go the desired route in the vasculature from the insertion to the end point. In many clinical situations accessing the patient&#39;s veins or arteries at the desired access point may be challenging because of the patient&#39;s anatomy or because of the blood vessel size and patency. For these reasons, devices and methods are needed to guide the insertion of a catheter into a blood vessel, the navigation of the catheter through the vasculature on the desired path, and the placement of the catheter at the desire location. 
       PRIOR ART 
       [0004]    Currently, ultrasound imaging is used to guide venipuncture and the insertion of a catheter in a vein and ECG-based guidance is used to confirm the tip location of the catheter at the cavo-atrial junction. Electromagnetic tracking, Doppler, ECG, and fluoroscopy are used to track (navigate) the intravascular catheter from the insertion point towards the cavo-atrial junction and chest X-rays, fluoroscopy, and ECG are used to place the catheter tip at the cavo-atrial junction. Further, transcutaneous ultrasound imaging is currently used to visualize the catheter in the vasculature after insertion and to check if the catheter has accidentally to an undesired location wherever ultrasound imaging is available at that location. Transesophageal ultrasound imaging can also be used to accurately place the catheter tip at the cavo-atrial junction. 
       Contributions of the Present Invention 
       [0005]    The purpose of the present invention is to provide a single easy-to-use, wireless device which combines ultrasound imaging and ECG-based tracking in order to guide a needle and a catheter for vascular access and to help position the catheter at the desired location in the vasculature. 
       SUMMARY OF THE INVENTION 
       [0006]    A new device and method are introduced herein to facilitate vascular access in general and the placement of central venous access devices in particular. In one embodiment, the device consists of the following components: a wireless ultrasound imaging handheld scanner, a Bluetooth ECG (electrocardiography) data acquisition module with patient ECG cable and sterile adaptor, and a mobile medical application running on a mobile platform (device), e.g., a tablet, smartphone or smart watch. Ultrasound imaging and/or ECG-based catheter guidance provided by the device disclosed herein can be used to independently or simultaneously visualize the catheter in the vasculature and/or guide its placement at the desired location. 
         [0007]    In another embodiment of the present invention, ultrasound imaging of the blood vessel targeted for vascular access can be used for assessing the blood vessel size prior to cannulating the blood vessel, for guiding an access needle into the targeted blood vessel, and for visualizing the catheter in the vasculature after the introduction of the catheter. 
         [0008]    In another embodiment of the present invention, ECG-based navigation of an intravascular catheter can be used for tracking such intravascular catheter in the vasculature and positioning such intravascular catheter at a desired location. 
         [0009]    In one aspect of the present invention, the ultrasound imaging handheld scanner contains all the electronics required to acquire and process ultrasound images and to transfer them wirelessly to a mobile platform device, e.g., a tablet or a smartphone. 
         [0010]    In another aspect of the present invention, the ECG data acquisition module contains all the electronics required to acquire and process tracking and positioning information for ECG-based catheter guidance and to transfer such information wirelessly to a mobile platform device, e.g., a tablet or a smartphone. 
         [0011]    In another aspect of the present invention, algorithms are introduced for processing and synchronization of ultrasound images and ECG signals. 
         [0012]    In another aspect of the present invention, user interfaces for the handheld ultrasound imaging scanner, the ECG data acquisition module, and the mobile medical application running on a mobile platform are introduced in order to simplify the use of ultrasound imaging and/or ECG-based guidance for catheter placement on mobile platforms. 
         [0013]    In another aspect of the present invention, a new vascular access method is introduced using simultaneous ultrasound imaging and ECG-based catheter guidance. According to the present invention, using ultrasound imaging of a catheter in the vasculature simultaneously with detecting ECG signals at the tip of the catheter provide accurate and reliable catheter location information in adult and pediatric population for most of patients conditions and clinical environments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1 : Overview of the device and method for vascular access according to the present invention 
           [0015]      FIG. 2 : Wireless hand held ultrasound imaging device according to the present invention 
           [0016]      FIG. 3 : Method of use of the ultrasound imaging device according to the present invention 
           [0017]      FIG. 4 : Needle guide for the ultrasound imaging device according to the present invention 
           [0018]      FIG. 5 : Block diagram of the ultrasound imaging device according to the present invention 
           [0019]      FIG. 6 : ECG device according to the present invention 
           [0020]      FIG. 7 : Block diagram of the ECG device according to the present invention 
           [0021]      FIG. 8 : User interface for ultrasound imaging according to the present invention 
           [0022]      FIG. 9 : User interface for the ECG device according to the present invention 
           [0023]      FIG. 10 : Block diagram of the software application for the ECG device according to the present invention 
           [0024]      FIG. 11 : Block diagram of the software application for ultrasound imaging according to the present invention 
           [0025]      FIG. 12 : User interface for patient information input according to the present invention 
           [0026]      FIG. 13 : User interface for ECG device settings according to the present invention 
           [0027]      FIG. 14 : Block diagram of the software application for the vascular access device according to the present invention 
           [0028]      FIG. 15 : User interface for the vascular access device according to the present invention 
           [0029]      FIG. 16 : User interface for ultrasound imaging settings according to the present invention 
           [0030]      FIG. 17 : Method for guiding the placement of catheters according to the present invention 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]      FIG. 1  illustrates the device and the method for vascular access according to the present invention. The patient  100  is subject to a vascular access procedure, whereby the catheter  140  is inserted in the vasculature, e.g., in the venous system at the access point  141 . The catheter  140  is pushed such that the catheter tip  134  navigates from the access point  140  towards a desired location in the vasculature, e.g., at the cavo-atrial junction (CAJ)  108  near the sino-atrial node  118  of the patient&#39;s heart  105 . On the way towards the cavo-atrial junction, the catheter tip reaches the subclavian vein  112  and the superior vena cava  107  and can inadvertently reach the internal jugular vein  110 , the right atrium  119  or the inferior vena cava  114 . The catheter  140  is inserted into the vein through a needle, which punctures the vein at the insertion point  141 , and which is removed after the insertion of the catheter. 
         [0032]    The hand held ultrasound imaging device  170  is used during the vascular access procedure in order to:
   a) Assess blood vessel size and select the appropriate catheter size of approximately ⅓ of the blood vessel size.   b) Verify blood vessel patency to see if there are potential obstacles along the catheter path   c) Guide the insertion of the needle into the right blood vessel and avoid injuring nerves or other relevant tissue.   d) Verify if the catheter is on the desired path or has reached an undesired location wherever such path and/or location can be visualized by ultrasound imaging.   
 
         [0037]    The ultrasound imaging device  170  has an ergonomic hand-held enclosure and communicates wirelessly with the mobile platform device  190  through a wireless communication channel  186  and  196 . The housing of the hand held imaging scanner  170  has a flat and wide surface  184  in order to allow for placing the housing on a flat surface, e.g., on a table. The wireless ultrasound imaging device  170  further comprises a linear transducer array  171  to transmit and receive ultrasound energy. A pair of buttons on the housing allows for the increase  177  and the decrease  176  of the field of view of the ultrasound image. The button  179  allows for stopping and starting ultrasound imaging in order to conserve power. The button  180  allows for switching between the ultrasound imaging mode, the ECG-based navigation mode and the combined ultrasound imaging—ECG-based navigation mode of the device  190 . A mechanical needle guide  172  can be mounted on the housing of the device  170  in order to allow for accurate guidance of a needle  174  in the field of view of the transducer array  171 . The cover  182  can be opened in order to allow for the exchange of rechargeable batteries. The LEDs  183  indicate: a) the status of the wireless connection, the battery status, and the on/off imaging status of the device  170 . 
         [0038]    The Bluetooth ECG data acquisition device  125  provides ECG signals from the patient&#39;s body and from the tip of the catheter to the device  190  via the Bluetooth communication channel  164 - 191 . The ECG signals are acquired by the device  125  from the patient via three leads: a reference lead  130  placed on the patient&#39;s abdomen right below the diaphragm  116 , a control lead  132  placed on the patient&#39;s skin over the jugular notch  102 , and catheter lead via the sterile adaptor (connector)  144 . The connector  144  can be an alligator clip which is connected to a stylet or to a guidewire inserted in the catheter  140 . The connector  144  can also be a saline solution adaptor which makes an electrical connection to saline solution flowing from a syringe  146  through the catheter hub  142  to the catheter tip  134 . Using the connector  144 , the device  125  can obtain ECG information from the tip  134  of the catheter  140 . The LEDs  150  indicate: the status of the Bluetooth communication, the battery status, and the on/off status of the device  125 . The ON/OFF button  152  is used to switch the device  125  on and off. Buttons  154  and  156  are used to increase and respectively decrease the scale on the display of the device  190  and/or the amplification of the ECG signal in the device  125 . The button  162  is used to create a reference ECG waveform on the display of the device  190 . The button  160  is used to save and print patient information and ECG waveforms in the memory of the device  190  and on an optional Bluetooth printer connected to the device  190 , respectively. 
         [0039]    The device  190  is a mobile platform, e.g., a tablet or a smartphone which runs a mobile application described in the present invention. On the display of the device  190  ultrasound images  192  and ECG waveforms  193  are displayed according to the present invention. Control buttons  194  are used to control the device  190  and to remotely control the ultrasound imaging device  170  and the ECG data acquisition device  125 . Ultrasound images, ECG waveforms, other patient information and voice can be transferred via the wireless communication channel  197  to other mobile devices in real time. 
         [0040]      FIG. 2  illustrates the wireless hand held ultrasound imaging device  200  according to the present invention. The ultrasound imaging device  200  consists of an ergonomic housing  230  which allows for the user to easily hold the housing in one hand and to perform all hand movements necessary for ultrasound imaging required by vascular access and needle puncture. A linear transducer array and the associated electronics are used to provide ultrasound images of appropriate resolution, penetration depth (field of view), and frame rate. Several buttons on the housing  230  allow an operator to access the most frequently used functions during ultrasound imaging with only one hand: decrease field of view ( 208 ) (shallower) and increase field of view ( 206 ) (deeper), switch between ECG-based guidance, combined ultrasound-ECG guidance, and ultrasound only operating modes ( 210 ) and starting and stopping ultrasound imaging in order to conserve power ( 212 ). The cover  220  can be opened in order to allow for the exchange of rechargeable batteries. The LEDs  222  indicate: a) the status of the wireless connection, the battery status, and the on/off imaging status of the device. 
         [0041]      FIG. 3  illustrates a method of use of the ultrasound imaging device according to the present invention. The ultrasound imaging device  300  is placed in a stable position with the flat surface of the housing  305  on a flat surface like a table or a cart or other flat surfaces  310  and with the transducer array  315  facing up. In this position of the scanner  300 , a single sterile operator can place a sterile bag  320  over the housing  300  and handle the scanner in such a way as not to compromise the sterile field while using the scanner  300  and operating its buttons  330 . 
         [0042]      FIG. 4  illustrates a needle guide for the ultrasound imaging device according to the present invention. The hand held scanner according to the present invention  400  can be fitted with a device  410  on either side or laterally in order to allow for guiding a needle  420  in the field of view of the transducer array  430  in-plane or out of plane. A sterile needle guide  410  can also be attached to the housing  400  after a sterile bag has been placed over the housing as described in  FIG. 3 . 
         [0043]      FIG. 5  illustrates a block diagram of the ultrasound imaging device according to the present invention. The linear transducer array of 16 to 256 transducer elements  502  is powered by the high voltage generator  510 . The transmit-receive switch  506  alternates between powering the transducer array  502  using the high voltage generator  510  during the transmit time and receiving the incoming signals generated by the incoming ultrasound echoes during receive time. The incoming signals generated by the incoming ultrasound echoes is processed by the beamformer  514  to form a focused ultrasound beam out of the 16 to 256 individual signals generated by the transducer array  502 . The high voltage generator  510 , the transmit-receive switch  506  and the beamformer  514  are synchronized, set up, and controlled by the control unit  520 . 
         [0044]    The image processing block  530  generates a raw ultrasound image out of the individual ultrasound beams provided by the beamformer  514  and processes the received individual beams and the raw ultrasound image in order to improve signal-to-noise ratio, contrast, and gain, and to reduce image speckles amongst others. The image processed by the image processing block  530  is then transferred to the scan converter  534 , which performs linear or bi-linear weighted interpolation and converts the image into a format that can be visualized on a display. 
         [0045]    The same processed image is also transferred to a feature extraction block  550  which extracts certain useful relevant features form the image which can serve for automatic control and adjustments of system settings. One such extracted relevant feature is the computed difference between subsequent images. In the case that such differences between subsequent images are not relevant for a certain period of time, it is assumed that the device is not in clinical use and the high voltage generator will automatically be turned off by the control unit  520  in order to conserver battery power. 
         [0046]    Other extracted relevant features are the average, the minimum and the maximum amplitudes in an image or in a certain area of an image. These features and their changes in time allow for performing automatic adjustment of the signal gain in order to optimize overall gain compensation and image contrast. 
         [0047]    Another extracted relevant feature is the offset or the delay from the image origin to the first returning ultrasound echo. This offset (delay) is used to compute typical initial internal ultrasound echoes in the transducer housing and to the patient skin. These initial echoes are very strong and are eliminated from the image display in order to not influence the display of the weaker ultrasound echoes coming from real targets in the patient&#39;s body. This offset (delay) is also used to compute the reference position for the image display in order to optimize the presentation of the useful ultrasound image on the display and not to waste display space for unwanted ultrasound echoes or delays. 
         [0048]    The image scan converted by  534  is compressed (lossy or lossless) by the data compression module  544  in order to decrease the data throughput through the WiFi communication channel  560 . The image processed by the block  530  can alternatively be sent to the data compression block  544  in the case that no scan converting of the image is needed to be performed in the hand held device  170 . The data compression module  544  can alternatively be set to no compression, i.e., it does not perform any compression on the ultrasound images. 
         [0049]    The ultrasound images scan converted or not and compressed or uncompressed, as well as the features extracted by the feature extraction module  550  are transmitted by the WiFi communication module  560  in real time to the display and receiving device  190  in  FIG. 1 . The extracted features by module  550  are also sent to the control unit  520  for automatic adaptive adjustments. 
         [0050]    The WiFi communication module  560  also receives commands and messages from the device  190  in  FIG. 1 . These commands and messages are interpreted and directed to the control unit  520  for execution. The hand held device  170  in  FIG. 1  has an user interface consisting of several buttons. The inputs from these buttons are processed by the user interface module  540  and directed to the control unit  520  for execution. The control unit  520  also controls the battery charger  528  and transmits status information about the status of the battery and of the hand-held device to the device  190  in  FIG. 1  through the WiFi communication channel  560 . 
         [0051]    The temperature sensor  570  measures the internal temperature in the housing of the hand held ultrasound imaging device. The control unit transmits this value over the WiFi communication channel  560  and takes appropriate power management measures to keep the internal temperature under the designated threshold, e.g., by turning off the high voltage generator or the battery charger  528 . The battery charger  528  charges the internal battery  524  which provides power for all the electronics of the device including for the high voltage generator  510 . 
         [0052]      FIG. 6  illustrates an ECG device according to the present invention. The device  600  is an ECG data acquisition and processing device with a wireless Bluetooth connection to the device  190  in  FIG. 1 . The device  600  has several connectors for connecting ECG leads: the connector and lead  610  can be connected to a control electrode, e.g.,  132  in  FIG. 1 , the connector and the lead  612  can be connected to a reference electrode, e.g.,  130  in  FIG. 1 , the connector and lead  614  can be connected to catheter, e.g.,  144  in  FIG. 1 , the connectors and the lead  616  can be connected to an active, noise-reduction electrode. 
         [0053]    The LED  622  indicates the status of the Bluetooth connection, the LED  620  indicates if the device  600  is on or off, the LED  624  indicates the internal battery status. The button  628  is used to turn on and off the device  600 . Pressing the button  630  sends a “Print/Save” command to the device  190  in  FIG. 1 . Pressing the button  632  sends a “Freeze” command to the device  190  in  FIG. 1 . Pressing the button  634  sends a command to increase the scale of the ECG signal to the device  190  in  FIG. 1 . Pressing the button  636  sends a command to decrease the scale of the ECG signal to the device  190  in  FIG. 1 . 
         [0054]    The LED  640  is on when the device  600  is charging. The micro USB connector  642  allows for charging the rechargeable battery of the device  600  via an USB cable. The device  600  transmits ECG and status information to the device  190  in  FIG. 1  via Bluetooth. ECG information includes raw ECG data, processed signals, and relevant features extracted from the ECG signal. 
         [0055]    The communication protocol over the Bluetooth communication channel between the device  600  and the device  190  in  FIG. 1  is structured as to allow the bidirectional transmission of multiple ECG signals, relevant features, and messages in real time. Each signal can be sampled and transmitted with up to 1000 samples per second per signal The Bluetooth communication channel of the device  600  can also receive messages, commands, and settings from the device  190  in  FIG. 1 . 
         [0056]      FIG. 7  illustrates a block diagram of the ECG device according to the present invention. ECG signals  702  as described for example by  610 ,  612 , and  614  in  FIG. 6  are input to the input optically isolated amplifier  704  which are then analog-to-digitally converted by the A/D converter  706 . The digital signals are processed by the signal processing module  730 . 
         [0057]    The signal processing performed by module  730  includes notch filtering of unwanted frequencies, high pass filtering for base line fluctuations reduction, common mode rejection and averaging. The signal processing performed by module  730  further includes synchronization between several ECG signals and the computation of signals using weighted averages of the input raw ECG signals. 
         [0058]    The feature extraction block  750  detects the R peaks of the ECG waveforms, marks the location of the ECG R-peak on the ECG signal and computes the heart rate using instantaneous and averaged computations. The feature extraction block  750  further detects ECG lead-off conditions, i.e., the conditions in which a lead is not connected to the patient. The signal processing results and the extracted relevant features of the signals are transmitted over the Bluetooth communication channel to the device  190  in  FIG. 1  using the Bluetooth module  760 . 
         [0059]    The Bluetooth module  760  also receives messages from the device  190  in  FIG. 1  and transmits commands to the control unit  720 . The control unit  720  also receives commands directly from the buttons situated on the housing of device as illustrated in  FIG. 6 , buttons  630 ,  632 ,  634 ,  636 . The control unit  720  controls the status of the LEDs  620 ,  622  and  624  illustrated in  FIG. 6 . 
         [0060]    The control unit  720  also controls the status and settings of the battery charger  712 , of the A/D converter  706 , of the signal processing block  730  and of the feature extraction block  750 . The battery charger  712  charges the internal battery  710 . 
         [0061]      FIG. 8  illustrates a user interface for ultrasound imaging according to the present invention. The user interface  800  is displayed on the touchscreen  802  of the device  190  in  FIG. 1 . Display window  804  is used to display ultrasound images received from the device  170  in  FIG. 1 . The depth scale  806  shows target mm markers and can be used to assess the sizes of objects visualized on the ultrasound images and their distance from the face of the transducer linear array. 
         [0062]    The field of view indicator  808  is a number indicating the maximum depth (distance from transducer face) which can be visualized at the current system settings. The field of view value can be changed by touching the screen over the display window  804  of the ultrasound image and by moving the finger up and down on the touch screen. Moving the finger up decreases the field of view and moving the finger down increases the field of view. Moving the finger up while touching the screen has the same effect of decreasing the field of view as pressing the button  208  in  FIG. 2 . Moving the finger down while touching the screen has the same effect of increasing the field of view as pressing the button  206  in  FIG. 2 . 
         [0063]    Tapping on the display window  804  when the ultrasound image is displayed in real time freezes the ultrasound image and tapping on the display window  804  when the ultrasound image is frozen unfreezes the ultrasound image and switches back to the real-time display mode. A frozen image can be displayed in a small window on the bottom of the display  804  for reference purposes. 
         [0064]    The touch button  812  is used to start the measurements mode. Touching the button  812  while in the measurements mode exits the measurements mode. The measurements mode can be used to assess the size of the objects visualized on the ultrasound image. When in measurements mode, when taping a first time on the display window  804 , a first marker is drawn at the tapping location. When tapping a second time on the display window  804 , a second marker is drawn at the tapping location, a dotted line is drawn between the two markers and the distance in mm between the two markers is displayed close to the dotted line or in one of the corners of the display window  804 . In order to move the location of one marker, the user has to drag and drop it to a new location by using a finger and touching the touch screen. A new dotted line is drawn and the new distance is calculated and displayed after the marker was dropped at a new location. 
         [0065]    The buttons  810  provide real-time control for ultrasound imaging. Touching the button  812  when in measurements mode, erases all graphics related to measurements and exits the measurement mode. Touching the button  814  switches the display mode to a combined displayed mode, in which ultrasound images and ECG signals are displayed at the same time on the display  802  as illustrated in  FIG. 15 . 
         [0066]    Turning the device  800  with 90 degrees in either direction ( 840 ) switches the display mode from ultrasound imaging (in portrait orientation) to the ECG mode and display (in landscape orientation) as illustrated in  FIG. 9 . If an ECG mode and display are not available, the action switches the ultrasound imaging display from a portrait mode to a landscape mode. 
         [0067]    The buttons  815  and  816  are used to change the overall gain setting of the ultrasound image: touching the button  815  increases the overall gain and touching the button  816  decreases the overall gain of the ultrasound image. 
         [0068]    Touching the button  819  enters a “Tools” menu as illustrated in  FIG. 16 . The field  830  of the graphical user interface provides general controls and additional functions for the ultrasound imaging device  170  in  FIG. 1 . 
         [0069]    The button  832  is divided into a left and a right button. The left button  832  provides a “Home” function, i.e., the mobile device  190  in  FIG. 1  goes to its home page without exiting the ultrasound imaging application described by the user interface  800 . The right button  832  provides a “Back” function, i.e., when touching this button, the menu navigation goes one step back to a previous state. 
         [0070]    Button  834  switches the display  802  to a “Patient” display illustrated in  FIG. 12 . Touching the button  836  switches to the Setting menu and user interface illustrated in  FIG. 16 . The display window  838  shows the battery levels of the batteries of the devices  170  and  190  from  FIG. 1 . 
         [0071]      FIG. 9  illustrates a user interface for the ECG device according to the present invention. The graphical user interface  900  is displayed on the touchscreen display of the device  190  in  FIG. 1 . The display window  902  displays a reference (frozen) ECG waveform  910  with a marker marking the R-peak of the ECG waveform. Display window  904  displays a real-time signal  960 , which can be an ECG waveform or a computed signal. The R-peak of the ECG waveform or a certain location in the computed signal is marked with a marker similar to the marker  912 . Display window  906  displays a real time ECG waveform from a skin (surface, control) ECG electrode. 
         [0072]    The ECG signals displayed in windows  904  and  906  are acquired and/or computed by the device  125  in  FIG. 1  and transmitted to the device  190  in  FIG. 1  over the Bluetooth communication channel  164 - 191  in  FIG. 1 . The signal scale of the signal displayed in display windows  904  can be increased or decreased using two-finger zoom over the touchscreen in the display area  904  to zoom out (increase signal scale) or zoom in (decrease signal scale). 
         [0073]    When tapping once on the display window  904  the signal in the display window  904  is copied and frozen as a reference signal in the display window  902 . When tapping on the display window  902 , the reference signal  910  is erased. The baseline of the signal  960  can be moved up and down in the display window  904  by touching the display window  904  and dragging up and down the ECG signal. The baseline of the signal  962  can be moved up and down in the display window  906  by touching the display window  906  and dragging up and down the ECG signal. The indicator  920  indicates the battery level of device  125  in  FIG. 1  and the indicator  922  indicates the battery level of device  190  in  FIG. 1 . 
         [0074]    Touching the button  926  switches to the patient information screen illustrated in  FIG. 12 . Touching button  930  prints the waveform displayed in window  902  together with patient information input as descried in  FIG. 12  on a Bluetooth printer connected to the device  190  in  FIG. 1  as described in  FIG. 13 . Touching the button  930  also saves the printed image as an image file in jpg format in the memory (internal or removable) of the device  190  in  FIG. 1 . Touching the button  930  also saves the ECG waveforms for a patient in a file in the memory (internal or removable) of the device  190  in  FIG. 1 . The file names containing printed images or case data are automatically generated. Touching the button  934  switches the graphical user interface to the display illustrated in  FIG. 13 . 
         [0075]    If an ultrasound imaging device  170  in  FIG. 1  is connected to the device  190  in  FIG. 1 , touching the button  938  or rotating the device  190  in  FIG. 1  with 90 degrees from landscape to portrait view switches the user interface to the one illustrated in  FIG. 8 . The field  940  displays the heart rate computed by device  125  in  FIG. 1  and transmitted in real time to the device  190  in  FIG. 1 . 
         [0076]    Field  944  shows the logo of the device and also serves as start/pause button for the real time display of the ECG waveform in display window  904 . The button  970  provides a “Home” function, i.e., the mobile device  190  in  FIG. 1  goes to its home page without exiting the ultrasound imaging application described by the user interface  900 . The button  974  provides a “Back” function, i.e., when touching this button, the menu navigation goes one step back to a previous state. The button  978  is a shortcut to Settings screen illustrated in  FIG. 13 . 
         [0077]      FIG. 10  illustrates a block diagram of the software application  1000  for the ECG device according to the present invention. The software application  1000  can run on any mobile platform fulfilling minimum requirements, e.g., tablets, smartphones, smart watches and other smart wearable and head-mounted technology. The application  1000  is built on a real-time multi-tasking operating system  1015  and structured into several threads of execution with appropriate execution priorities and computing and memory resources. 
         [0078]    The Bluetooth communication thread  1010  ensures the communication over the Bluetooth communication channel  164 - 191  in  FIG. 1  between the devices  125  and  190  in  FIG. 1  and between the device  190  in  FIG. 1  and a connected Bluetooth printer. Upon user request, the “Print” thread  1020  prints ECG waveforms and patient information on a Bluetooth printer, when such a printer is connected to the device  190  in  FIG. 1 . The “Print” thread  1020  also saves data files to the storage medium available in the device  190  in  FIG. 1 . The “Print” thread  1020  performs the functions described in  FIG. 9  for button  930 . The “Print” thread  1020  continuously saves in real-time the data received from the device  125  in  FIG. 1  in a memory buffer. 
         [0079]    Upon touching the button  930  in  FIG. 9 , the data from the internal memory buffer is converted into an optimized file format and also transferred to a permanent storage medium. The thread “Help”  1025  is responsible for all real-time and off-line activities related to providing real time context dependent, educational, and on line help to the user. 
         [0080]    The user can obtain real time context dependent help regarding the system functionality by touching a question mark drawn on the user interface, dragging and dropping it on the region of interest on the graphical user interface, about which the user wants to obtain help. 
         [0081]    Educational help is provided in the form of pictures, text, and movies which the user can select from a list of available choices. 
         [0082]    On line help can be obtained by connecting to available remote help tools, e.g., clinical information database. 
         [0083]    Additionally, the user can obtain help using the phone or the wireless communication capabilities of the mobile platform device  190  in  FIG. 1 . The user can dial a number and can share in real time the information displayed on the graphical user interface, for example on the display in  FIG. 9 , with the person answering the phone call. 
         [0084]    The thread “Settings”  1030  is responsible for activities related to setting and maintaining the system status, including setting and marinating the status of devices  125  and  190  in  FIG. 1  through appropriate communication. 
         [0085]    The thread “ECG”  1040  is responsible for maintaining the Bluetooth communication and for receiving and transmitting messages from and to the device  125  in  FIG. 1 , for displaying signals and information, including relevant features on the display of device  190  in  FIG. 1  as illustrated in  FIG. 9  and for the user interface interaction related to the display illustrated and described in  FIG. 9 . 
         [0086]    The thread “Patient”  1050  is responsible for implementing the activities related to the “Patient” button  926  in  FIG. 9 . A user interface corresponding to thread  1050  is illustrated in  FIG. 12 . 
         [0087]    The “Playback” thread  1060  is responsible for activities related to playing back patient data saved to file. When a case data file is opened using the “Open Img” thread  1070 , the thread “Playback”  1060  reads the contents of the file and post processes it as if the data was real time data. I.e., the data can be modified through the user interface as it is displayed on the display illustrated in  FIG. 9  using all real time controls as if the data was real time data. For example, the user can change the signal scale using a finger zoom function over the display  904 , modify the baseline of the signals by touching, dragging and dropping the signals, freezing the signal in display window  902 , or modifying the signal scale of the signal displayed in display window  906 . The thread “Open Img”  1070  is responsible for activities related to finding and opening a saved file. A file can be saved either as an image file containing the printout of the information printed to a Bluetooth printer or as a case data file containing the signals and information for a patient received from the device  125  in  FIG. 1 . 
         [0088]      FIG. 11  illustrates a block diagram of the software application  1100  for ultrasound imaging according to the present invention. The software application  1100  can run on any mobile platform fulfilling minimum requirements, e.g., tablets, smartphones, smart watches and other smart wearable and head-mounted technology. The application  1100  is built on a real-time multi-tasking operating system  1105  and structured into several threads of execution with appropriate execution priorities and computing and memory resources. 
         [0089]    The wireless communication thread  1110  ensures wireless communication over the communication channel  186 - 196  in  FIG. 1  between the devices  170  and  190  in  FIG. 1  and between the device  190  in  FIG. 1  and a Bluetooth or other wireless printer connected to the device  190  in  FIG. 1 . In another embodiment of the present invention, the thread  1110  can ensure real-time communication with other wireless devices and the real-time broadcasting over the communication channel  197  of the ultrasound images received from the device  170  in  FIG. 1 . 
         [0090]    The “Measurements” thread  1115  is responsible for activities related to measurements of object on the ultrasound image as described in  FIG. 8 . 
         [0091]    The thread “Help”  1120  is responsible for all real-time and off-line activities related to providing real time context dependent, educational, and on line help to the user. The user can obtain real time context dependent help regarding the system functionality by touching a question mark drawn on the user interface, dragging and dropping it on the region of interest on the graphical user interface, about which the user wants to obtain help. 
         [0092]    Educational help is provided in the form of pictures, text, and movies which the user can select from a list of available choices. 
         [0093]    On line help can be obtained by connecting to available remote help tools, e.g., clinical information database. 
         [0094]    Additionally, the user can obtain help using the phone or the wireless communication capabilities of the mobile platform device  190  in  FIG. 1 . The user can dial a number and can share in real time the information displayed on the graphical user interface, for example on the display in  FIG. 9 , with the person answering the phone call. 
         [0095]    The thread “Patient”  1125  is responsible for implementing the activities related to the “Patient” button  834  in  FIG. 8 . A user interface corresponding to thread  1125  is illustrated in  FIG. 12 . 
         [0096]    The thread “Settings”  1130  is responsible for activities related to setting and maintaining the system status, including setting and maintaining the status of devices  170  and  190  in  FIG. 1  through appropriate communication. 
         [0097]    The thread “Data Compression”  1135  performs data decompression on the ultrasound imaging data received from device  170  in  FIG. 1 , if the device was set to performed data compression as described in  FIG. 5 . 
         [0098]    The thread “Scan Converter”  1140  performs scan conversion operations on the ultrasound imaging data received from device  170  in  FIG. 1  if the device  170  does not perform such scan conversion operations. A scan conversion operation is defined as a conversion between the data structures of ultrasound images as acquired by the beamformer  514  in  FIG. 5  and the data structures of the corresponding ultrasound images as displayed on the display  804  in  FIG. 8 . 
         [0099]    The thread “Feature Extraction” extracts relevant features from the ultrasound image received from the device  170  in  FIG. 1 . Such relevant features may include averages, gray scale distributions, recognition of active the field of view, recognition of idle states of the device  170  in  FIG. 1 , the computation of the image attenuation as a function of imaging depth, and the recognition of the boundaries and of the characteristics of certain objects in the ultrasound image. 
         [0100]    The thread “Image processing”  1150  is responsible for image stabilization and enhancement, e.g., low pass, high pass, band pass and selective filtering, time gain compensation, rescaling, and reorientation of ultrasound images. 
         [0101]    The thread “Beamformer”  1155  is responsible for setting and controlling the module beamformer  514  in  FIG. 5 . Such setting and controlling include selecting beamforming tables computed by thread  1160 , setting the field of view, the amplification scale, and the power management of the device  170  in  FIG. 1  determined by thread  1165  as a function of overall system settings and imaging parameters. Such setting and controlling may result from user input or automatically from computations by the threads  1135 ,  1140 ,  1145 , or  1150  and are transmitted to the device  170  in  FIG. 1  over the wireless communication channel  196 - 186  in  FIG. 1 . 
         [0102]      FIG. 12  illustrates a user interface for patient information input according to the present invention. The display window  1205  displays a real-time ECG waveform from the control electrode  132  in  FIG. 1  connected to the patient&#39;s skin. The heart rate displayed in field  1265  in real time is computed by the device  125  in  FIG. 1  based on the ECG waveform acquired from the control electrode  132  in  FIG. 1 . 
         [0103]    The field  1240  displays an alphanumeric keyboard which can be used by touching the touchscreen of the device  190  in  FIG. 1 . The soft alphanumeric keyboard  1240  is automatically displayed if any of the input fields  1210 ,  1215 ,  1200 ,  1225  or  1230  are touched. The field  1200  labeled “Notes” is a general text input field. The field  1215  is labeled “Device Type” and the user can input information about the vascular access device (VAD) used in the clinical procedure. The field  1210  is labeled “Patient” and the user can input the name and/or the ID of the patient undergoing the vascular access device placement procedure. The field  1230  is labeled “Institution” and the user can input the name of the clinical institution and/or the name of the clinician performing the VAD placement procedure. Field  1225  is labeled “Inserted Length” and the user can input the insertion length of the VAD at the end of the VAD placement procedure. 
         [0104]    The information input in the alphanumeric fields is stored in the patient&#39;s file and printed on paper on the Bluetooth printer, if such a printer is connected, when the user touches the button  930  in  FIG. 9 . Touching the button  1250  opens a dialog box and a display window allowing the user to select for visualization archived images or to select a file to playback archived patient data. 
         [0105]    The button  1255  switches the screen to the “Settings” display illustrated in  FIG. 13 . The button  1260  is labeled “New Patient”. When touching this button, all input fields of the display  1200  are cleared and the memory used for temporary storage of patient information and case data is reinitialized. Field  1270  shows the logo of the device. 
         [0106]      FIG. 13  illustrates a user interface for ECG device settings  1300  according to the present invention. The display window  1305  displays an ECG waveform of the patient from the electrodes connected to the skin as a control electrode. The heart rate displayed in field  1310  in real time is computed based on the ECG waveform displayed in display window  1305 . Field  1315  shows the logo of the device. 
         [0107]    Touching the button  1320  switches the display to a display window allowing for setting up a Bluetooth printer. Touching the button  1325  switches the display to the display illustrated in  FIG. 12 . The display window  1330  displays messages related to the Bluetooth communication between the devices  190  and  125  in  FIG. 1  and between the device  190  in  FIG. 1  and a Bluetooth printer. The display window  1330  also displays messages related to the wireless communication between the devices  190  and  170  in  FIG. 1 , if a device  170  is connected. The display window  1335  lists all discovered Bluetooth devices including the device  125  in  FIG. 1  and a Bluetooth printer and allows for the selection of desired devices. The button  1340  is labeled “Refresh”. Touching this button restarts the discovery of Bluetooth devices displayed in window  1335 . The button  1345  is labeled “Connect”. 
         [0108]    Touching the button  1345  allows for establishing Bluetooth communication between the device  190  in  FIG. 1  and the device selected in window  1335 , i.e., a particular device  125  in  FIG. 1 . One or more devices  125  in  FIG. 1  can be discovered but only one such device can be connected at any one time. 
         [0109]    The drop-down selection box  1350  is labeled “ECG rate” and allows for the selection of the rate for the A/D sampling of the ECG signals performed by device  125  in  FIG. 1 . The drop-down selection box  1355  is labeled “IV Gain” and allows for the selection of the acquisition amplification and/or display scale of the intravascular ECG signal acquired by device  125  in  FIG. 1 . The drop-down selection box  1360  is labeled “CE Gain” and allows for the selection of the acquisition amplification and/or display scale of the ECG control signal acquired by device  125  in  FIG. 1 . The drop-down selection box  1365  allows for the selection of a notch filter implemented by the device  125  in  FIG. 1 . The parameters selected using the selection boxes  1350 ,  1355 ,  1360 , and  1365  are sent by the device  190  to the device  125  in  FIG. 1  upon selection over the Bluetooth communication channel  191 - 164 . 
         [0110]    Touching the button  1380  labeled “SW Version” displays the version of the mobile application running on the device  190  in  FIG. 1  and of the firmware of devices  125  and  170  in  FIG. 1 . 
         [0111]    The drop-down selection box  1385  allows for the selection of the display scale and/or attenuation coefficient for the ECG control signal displayed in window  1305 . The signal attenuation for display purposes is performed by the application running on the device  190  in  FIG. 1  and by the thread  1040  shown in in  FIG. 10 . Touching the button  1390  resets the settings of the devices  125 ,  170 , and  190  in  FIG. 1  to factory defaults. 
         [0112]    The check box  1370  is labeled “R-Peak”. The user can check and uncheck the box  1370  by touching it. When checked, the device  125  in  FIG. 1  computes the location of the R-peak in the ECG waveform and the device  190  in  FIG. 1  displays a marker over the R-peak of the ECG waveform on the display illustrated in  FIG. 9 . The user can check and uncheck the box  1375  by touching it. When checked, the device  125  in  FIG. 1  computes another specific signal related to the tip of the catheter of the vascular access device and the device  190  in  FIG. 1  displays this signal in the display window  904  illustrated in  FIG. 9 . 
         [0113]      FIG. 14  illustrates a block diagram of the software application for the vascular access device according to the present invention. The software application  1400  runs on the device  190  in  FIG. 1  on top of a real-time multitasking operating system  1405 . The software module  1410  ensures Bluetooth communication with the device  125  over the communication channel  191 - 164  in  FIG. 1  and with a Bluetooth printer. Software module  1415  ensures wireless communication over a wireless channel using a wireless protocol between the devices  190  and  170  over the communication channel  196 - 186  in  FIG. 1 . Software module  1415  further ensures wireless communication over a wireless channel using a wireless protocol between the device  190  and another wireless device for the purpose of broadcasting in real time patient information, signals and images acquired from the patient by the device according to the present invention. 
         [0114]    In another embodiment of the present invention, the software module  1415  also includes capabilities to transfer patient information, signals and images in real time to another device over a wireless phone and/or smartphone connection. 
         [0115]    The ECG application module  1425  has the functions and the block diagram illustrated in  FIG. 10 . The ultrasound imaging application module  1430  has the functions and the block diagram illustrated in  FIG. 11 . The synchronization module  1440  performs synchronization between the ECG application  1425  and the ultrasound imaging application  1430 . The synchronization performed by the module  1440  includes synchronization between the resources of the device  190  in  FIG. 1  allocated to the two applications  1425  and  1430 , timing synchronization between applications  1425  and  1430 . 
         [0116]    One method of timing synchronization according to the present invention is ECG-triggered ultrasound imaging and information processing. In such ECG-triggered timing synchronization, the ECG signals and the ultrasound images are processed based on a trigger in the ECG waveform, for example based on the occurrence of an R-peak in the control ECG signal. When such a trigger occurs, certain parameters of the ultrasound image received from the device  170  in  FIG. 1  and certain parameters of the signals received from device  125  in  FIG. 1  are computed by the information processing block  1420 . 
         [0117]    Examples of such computed parameters include blood vessel sizes. Since the blood vessel diameter changes during the heart cycle, determining the blood vessel size at the same moment in time in each heart cycle leads to a more accurate determination of the vessel size. The determination of the blood vessel size triggered by ECG can be computed or determined with user interaction through the user interface illustrated in  FIG. 15 . Accurate estimation of blood vessel size is important for the determination of the size of the vascular access device catheter. 
         [0118]    Another type of synchronization and processing performed by modules  1440  and  1420  is the correlation of the ultrasound image with the ECG signal at the tip of the catheter at certain locations in the vasculature, for example in the internal jugular vein. The user interface module  1435  is controlling the user interface illustrated in  FIGS. 8, 9, 12, 13, 15, and 16 . 
         [0119]    The user interface module  1435  together with the synchronization module  1440  are responsible for switching between the ultrasound imaging interface illustrated in  FIG. 8  and the ECG interface illustrated in  FIG. 9  when the device  190  in  FIG. 1  rotated by 90 degrees as explained in  FIGS. 8  ( 840 ) and  9  ( 950 ). 
         [0120]      FIG. 15  illustrates a user interface for the vascular access device according to the present invention. The graphical user interface  1500  is displayed on the touch screen of a mobile device  190  in  FIG. 1 , e.g., a tablet or a smartphone. A simplified version of this interface can be displayed on a smart watch or on head mounted device. The display window  1510  display ultrasound images acquired and processed by the device  170  in  FIG. 1  and transmitted to device  190  in  FIG. 1  over a wireless communication channel. 
         [0121]    An ultrasound image  1570  is presented on the display window  1510  with the origin of the image  1570  on the top of the screen and with the deepest field of view of the image on the bottom of the image  1570 . The display scale in mm  1515  is displayed to the right of the display window  1510 . Objects closer to the skin  1575  are displayed closer to the origin of the ultrasound image  1570 , i.e., closer to the top of the image  1570 . Deeper objects  1580  are displayed closer to the bottom of the image  1570 . The devices  170  and  190  in  FIG. 1  ensure good enough resolution and contrast in order to clearly depict in the ultrasound image  1570  veins ( 1575 ), arteries ( 1580 ) and catheters of at least 3 Fr in size  1585  positioned inside blood vessels  1575 . 
         [0122]    The devices  170  and  190 , as well as the communication channel  196 - 186  in  FIG. 1  ensures communication speed and data throughput high enough in order to display real time ultrasound images at minimum 10 images per second. The display window  1520  displays the field of view, i.e., the maximum target depth for which ultrasound images can be acquired for a specific setting of the device  170  in  FIG. 1 . The display window  1510  for ultrasound images ensures the user interface functionality described in  FIG. 8  for the display window  804 . 
         [0123]    The display window  1560  displays ECG and other signals  1565  acquired and processed by the device  125  in  FIG. 1  and transmitted to the device  190  in  FIG. 1  over a Bluetooth communication channel ( 164 - 191  in  FIG. 1 ). The display window  1560  ensures the user interface functionality described in  FIG. 9  for display window  904 . Touching the button  1540  switches the display and the graphical user interface to the user interface described in  FIG. 16 . Touching the button  1545  enables printing to a wireless printer. Depending on the system settings, either the ultrasound image  1570  or the signal  1565  or both can be printed on one or two different printers. For example, the ultrasound image  1570  can be printed on wireless printer using Direct WiFi and the signal  1565  can be printed on a Bluetooth printer. 
         [0124]    Touching the button  1545  also enables saving of patient information, ECG signals and frozen ultrasound images in dedicated files on the selected storage medium of the device  190  in  FIG. 1 . Touching the button  1550  switches the user interface of the device  190  in  FIG. 1  to the user interface presented in  FIG. 8 . Touching the button  1555  switches the user interface of the device  190  in  FIG. 1  to the user interface presented in  FIG. 9 . 
         [0125]    Buttons  1590  and  1594  provide a “Home” and a “Back” function respectively, as described in  FIG. 9 , buttons  970  and  974  respectively. The field  1530  displays the heart rate computed by the device  125  in  FIG. 1 . The field  1535  displays the logo of the device. The field  1535  also serves as a toggle button for the selection of the signal  1565  displayed in display window  1560 . One out of two or more signals acquired and/or computed by the device  125  in  FIG. 1  can be selected to be displayed in window  1560 . The button  1525  is a toggle button. Touching the button  1525  enables or disables synchronization function between the ECG signal and the ultrasound image as described in  FIG. 14 . 
         [0126]      FIG. 16  illustrates a user interface for ultrasound imaging settings and tools according to the present invention. The display window  1600  is displayed on the screen of the device  190  in  FIG. 1  and is divided into a “Settings” section  1605  and a “Tools” Section  1660 . The setting called “Compression”  1610  allows for the selection of the compression ratio for the ultrasound images transferred from the device  170  to the device  190  over the communication channel  196 - 186  in  FIG. 1  through a drop down selection box. When the compression is set to off, ultrasound images are transferred uncompressed. 
         [0127]    Touching the button  1636  toggles on and off the ECG trigger  1614 . When turned on, the ECG trigger works as described in  FIG. 14 . The setting TGC curve  1618  allows for the selection of a time-gain compensation (TGC) curve used to optimized image quality by compensating ultrasound attenuation due to depth. The TGC can be switched off, in which case the blocks  530  in  FIG. 5 and 1150  in  FIG. 11  do not perform any attenuation compensation on the ultrasound image. One TGC curve can be selected out of a set of predefined TGC curves by using the drop box  1634 . The predefined set of TGC curves allows for choosing the optimal ultrasound attenuation compensation in a typical clinical situation, e.g., when working on neonates, when placing peripherally inserted central lines (PICC), when placing implantable ports, when accessing the blood vessels by femoral access. 
         [0128]    The “Scan Converter” setting  1620  allows for turning on and off with the help of the selection button  1638  the scan converter function performed by block  534  in  FIG. 5 . When the scan converter function performed by block  534  in  FIG. 5  is turned off, then automatically the scan converter function  1140  in  FIG. 11  is turned on and reciprocally, such that only one scan converter function is active at one time. 
         [0129]    The WiFi select field  1624  displays a list of available WiFi devices in the display window  1630 . By touching the appropriate name listed in display window  1630 , the device  170  can be wirelessly connected, e.g., through a direct wireless connection to the device  190  in  FIG. 1 . The Button Configuration field  1628  allows the user to configure the buttons  1640  of device  170  in  FIG. 1  to perform functions selected from the drop down list  1642 . The user touches one of the buttons  1640  to select it and the selects the desired function for that button from the drop down list  1642 . Touching the selected button again allocated the selected function to that button. 
         [0130]    The “Tools” menu displayed in display window  1660  allows for performing certain less frequently used functions. Touching the button “Save”  1665  saves patient case data to a file on the storage medium of the device  190  in  FIG. 1 . Touching the button “Play”  1670  allows for selecting a stored patient file and playing it back on a display window for ultrasound images on the device  190  in  FIG. 1 . Touching the “Print” button  1675  allows for printing an ultrasound image including measurements to a connected wireless printer. Touching the “Diag” button brings up a number of diagnostics options used to verify the functionality of the devices  170  and  190  in  FIG. 1 . Buttons  1690  and  1692  provide a “Home” and a “Back” function respectively, as described in  FIG. 9 , buttons  970  and  974  respectively. Display window  1694  indicates the battery level of device  170  in  FIG. 1  and display window  1696  indicates the battery level of device  190  in  FIG. 1 . 
         [0131]      FIG. 17  illustrates a method for vascular access according to the present invention consisting of the steps described herein below. The displays illustrated by  1700 ,  1710 ,  1720 ,  1730 ,  1740 ,  1750 , and  1760  are simplified forms of the display illustrated and described in  FIG. 15  displayed on the device  190  in  FIG. 1 . The ultrasound images illustrated in  FIG. 17  are acquired by the device  170  in  FIG. 1  and transmitted to the device  190  in  FIG. 1  according to the present invention. The ECG signals illustrated in  FIG. 17  are acquired by the device  125  in  FIG. 1  and transmitted to the device  190  in  FIG. 1  according to the present invention. The method for vascular access according to the present invention consists of the following steps: 
         [0132]    1. Estimation of the blood vessel size considered for vascular access illustrated by the display  1700 . The targeted blood vessel for vascular access  1702  is visualized on the ultrasound image in  FIG. 15 . The skin (surface, control) ECG signal  1708  is selected to be displayed as described in  FIG. 15 . In order to increase measurement accuracy on the ultrasound image, ECG-triggered ultrasound imaging described in  FIG. 14  is enabled by using the button  1525  in  FIG. 15 . The blood vessel diameter  1704  is measured as described in  FIG. 8  and displayed in the field  1706 . Thus, the user can estimate the size of the vascular access device which is recommended to be approximately one third of the blood vessel diameter. The patency of the targeted blood vessel is also evaluated at this step using ultrasound imaging along the blood vessel and visualizing differences in the blood vessel diameter along the blood vessel. The diameter of the blood vessel may decrease due to obstructions such as blood clots, tumors, or other causes. In general, the size of the access device catheter should be one third of the minimum diameter of the targeted blood vessel on the desired catheter path. 
         [0133]    2. Puncture and access of the targeted blood vessel illustrated by the display  1710 . In display  1710  an uncompressible artery  1716  and a compressible vein  1714  are illustrated, displayed by ultrasound imaging in case of peripheral access. In the ultrasound image, the access needle  1712  is also illustrated. The access needle can be inserted in the targeted blood vessel under ultrasound guidance freehanded or by using the needle guide described in  FIG. 4 . The skin (surface, control) ECG signal  1718  displayed simultaneously with the ultrasound image is used to monitor the patient&#39;s heart rate and the presence of any heart rhythm abnormalities, e.g., extra systoles. The heart rate and heart rhythm abnormalities are computed using the detection of the R-peak  1719  of the ECG waveform as described in  FIG. 9  and displayed in the field  1530  in  FIG. 15 . 
         [0134]    3. Checking the catheter path within the blood vessels illustrated by the display  1720 . Wherever accessible to ultrasound imaging, the targeted blood vessel path for the catheter placement is visualized, for example in a longitudinal view  1722 . If the catheter  1724  is in the targeted blood vessel, the catheter can be visualized on the ultrasound image, as well as the catheter tip  1726 . An ECG signal  1728  is displayed simultaneously with the ultrasound image. A skin (surface, control) ECG signal is selected for the display  1728  and used to monitor the patient&#39;s heart rate and the presence of any heart rhythm abnormalities, e.g., extra systoles, for example when the catheter touches the wall of the right atrium. The heart rate and rhythm abnormalities are computed using the detection of the R-peak  1729  of the ECG waveform as described in  FIG. 9  and displayed in the field  1530  in  FIG. 15 . An intravascular ECG signal at the tip of the catheter is selected for the display  1728  and used to correlate in real time the position of the tip of the catheter  1726  visualized on the ultrasound image with the ECG waveform from the tip of the catheter at that location. Checking the catheter path within the blood vessels illustrated by the display  1720  can be performed either by longitudinal ultrasound imaging, i.e., along a blood vessel or by transversal ultrasound imaging, i.e., perpendicular on a blood vessel. 
         [0135]    4. Checking abnormal catheter locations as illustrated in  Figure 1730 . If the catheter did not follow the desired path through the vasculature and could not be visualized in step 2, abnormal positions of the catheter within the vasculature are checked as illustrated by  1730 . Wherever accessible to ultrasound imaging, the possible abnormal catheter locations, e.g., in the internal jugular vein are visualized. A catheter  1734  can be identified in a blood vessel in a transversal view  1732 . Checking the catheter path within the blood vessels illustrated by the display  1730  can be performed either by longitudinal ultrasound imaging, i.e., along a blood vessel or by transversal ultrasound imaging, i.e., perpendicular on a blood vessel. A skin (surface, control) ECG signal is selected for the display  1736  and used to monitor the patient&#39;s heart rate and the presence of any heart rhythm abnormalities, e.g., extra systoles, for example when the catheter touches the wall of the right atrium. The heart rate is computed using the detection of the R-peak  1738  of the ECG waveform as described in  FIG. 9  and displayed in the field  1530  in  FIG. 15 . An intravascular ECG signal at the tip of the catheter is alternatively selected for the display  1736  and used to correlate in real time the position of the tip of the catheter visualized on the ultrasound image  1734  with the ECG waveform from the tip of the catheter at that location. Checking the catheter path within the blood vessels illustrated by the display  1730  can be performed either by longitudinal ultrasound imaging, i.e., along a blood vessel or by transversal ultrasound imaging, i.e., perpendicular on a blood vessel. 
         [0136]    5. Approaching the cavo-atrial junction as illustrated in  1740 . As described in the literature, as the catheter tip of the vascular access device approaches the cavo-atrial junction the P-wave  1744  of the ECG waveform  1742  increases. The P-wave can be easily identified as being the predominant waveform to the left of the R-peak  1748  of the QRS complex  1746  of the ECG-waveform  1742 . 
         [0137]    6. In order to place the catheter tip at the cavo-atrial junction, the catheter is first advanced beyond the cavo-atrial junction until the P-wave of the ECG waveform  1755  situated to the left of the marker  1758  indicating the peak of the R-wave  1759  starts to decrease or becomes biphasic with a negative first peak  1756  and a predominant second positive peak  1757 . Then, the catheter is pulled back to the cavo-atrial junction until the P-wave  1752  situated to the left of the marker  1754  of the R-peak of the R-wave  1753  of the ECG waveform  1751  reaches its maximum positive amplitude without presenting the biphasic aspect identified by  1756  and  1757 . 
         [0138]    7. The ultrasound image showing a blood vessel of interest  1761  and the catheter  1762  inside that vessel, as well as the ECG waveform  1764  corresponding to the catheter tip location at the target location are frozen on display  1760  and saved to the patient file using the user interface described in  FIG. 15 . The information is printed wirelessly ( 1770 ) to a wireless printer  1780  for documentation purposes.