Abstract:
A method for locating a blood vessel includes transmitting waves into a body part through which a blood vessel runs, detecting reflections of the waves, determining a location of the blood vessel responsive to detecting the reflections of the waves, and providing a visual indication at a location that is adjacent to the blood vessel.

Description:
BACKGROUND  
       [0001]     A medical professional is often charged with the task of injecting a medicine or drug into a patient. This task may be complicated if an appropriate blood vessel for receiving an injection is not detected by the medical professional. A blood vessel may be undetectable for various reasons, including for example, if the patient has very low blood pressure, is obese, or is very young. Detecting a blood vessel through which to provide a patient with a needed drug or medicine may save a patient&#39;s live. Conversely, failing to detect such a blood vessel can prevent the patient from receiving a life- saving medicine or drug. Prior art systems and methods have not enabled emergency medical professionals to quickly and accurately determine a precise location where a drug or medicine may be injected into a patient in cases where blood vessels are not visible to the naked eye. Therefore, there exists a need for improved systems and methods for locating blood vessels.  
       SUMMARY  
       [0002]     Systems and methods for locating a blood vessel are disclosed. An embodiment of a method for locating a blood vessel includes transmitting waves into a body part through which a blood vessel runs, detecting reflections of the waves, determining a location of the blood vessel responsive to detecting the reflections of the waves, and providing a visual indication at a location that is adjacent to the blood vessel.  
         [0003]     An embodiment of a system for locating a blood vessel includes a transmitter configured to transmit waves into a body part through which a blood vessel runs, a receiver configured to receive reflections of the waves transmitted by the transmitter, a processor that is programmed to determine a location of the blood vessel responsive to the receiver receiving the reflections of the waves, and a display device that is configured to provide a visual indication at a location that is adjacent to the blood vessel responsive to the processor determining the location of the blood vessel.  
         [0004]     Other systems, methods, features and/or advantages will be or may become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and/or advantages be included within this description and be protected by the accompanying claims 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a simplified block diagram of an embodiment of the blood-vessel locating-system.  
         [0006]      FIG. 2A  is a flow chart illustrating a blood-vessel locating-method according to an embodiment of the present invention.  
         [0007]      FIG. 2B  is a flow chart illustrating an exemplary method of the blood-vessel locating-method.  
         [0008]      FIG. 3A  is a schematic diagram depicting a frontal view of a strap-mounted blood-vessel locating-system.  
         [0009]      FIG. 3B  is a schematic diagram depicting a plan view of the strap-mounted blood-vessel locating-system.  
         [0010]      FIG. 4A  is a schematic diagram depicting a frontal view of a strap-mounted blood-vessel locating-system.  
         [0011]      FIG. 4B  is a schematic diagram depicting a plan view of the strap-mounted blood-vessel locating-system.  
         [0012]      FIG. 5  is a schematic diagram illustrating the strap-mounted blood-vessel locating-system being used to indicate the location of a blood vessel that is flowing through a patient&#39;s arm. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0013]      FIG. 1  is a simplified block diagram of an embodiment of the blood-vessel locating-system  100 . The locating system  100  includes a transmitter  101 , a receiver  102 , and a display device  104  that are coupled to a processor  103 . In a preferred embodiment, two or more receivers  102  are included in the blood-vessel locating-system  100 .  
         [0014]     The display device  104  may comprise, for example, LEDs, a laser pointer and/or an LCD display. One advantage of using LCDs is that they can be easily read in bright light and in the dark (with the addition of a back light). Custom LCD displays enable the use of graphic icons, text, gauges, and indicators.  
         [0015]     In one embodiment, the transmitter  101  transmits ultrasound waves which reflect off the interior of a body part (e.g., a patient&#39;s arm) and which are received by the receiver  102 . The receiver  102  converts the received ultrasound waves into electric signals and sends the electric signals to the processor  103 .  
         [0016]     The processor  103  analyzes the electric signals received from the receiver  102  to determine the location of one or more blood vessels. The processor  103  then sends signals to a display device  104  causing the display device  104  to provide one or more visual indications at one or more locations that are adjacent to the respective detected blood vessel(s). The processor  103  may be configured to process buffered signals, and may have a DSP core or may interface with a DSP processor. Two or more processors  103  may alternatively be used to enable operation of the blood-vessel locating-system  100 .  
         [0017]     In one embodiment, the blood-vessel locating-system  100  samples received signals at or above the corresponding Nyquest rate and applies a fast Fourier transform (FFT) to get the signals into the frequency domain. The blood-vessel locating-system  100  then analyzes the data with appropriate algorithms to determine blood vessel locations.  
         [0018]     According to another embodiment of the invention, undersampling (also called bandpass sampling), allows the sampling frequency to be up to three hundred times less than that used in FFT. Undersampling works because loss of aliased frequency components of the input signal is avoided by properly selecting a sampling frequency and bandwidth for the input signals.  
         [0019]     According to yet another embodiment of the invention, demodulation is used to reduce the required sampling frequency and buffer size. Most common demodulator designs use quadrature demodulation to get a complex signal that requires two analog mixers per channel. However, the blood-vessel locating-system  100  may be implemented using only one mixer per channel since the direction of blood flow is typically irrelevant.  
         [0020]     The blood-vessel locating-system  100  may use a linear array of receivers  102  to locate a vessel. An array of receivers  102  may be placed over a vessel by an examiner. If the array of receivers  102  is centered over the vessel, the signals received by the receivers  102  on either side of the transmitter will match. If the array of receivers  102  is not centered, then the received signals will not match. Signals may be processed to show a spike representing the received Doppler shift with respect to time. Trigonometric algorithms may be used to derive the location and depth of a vessel.  
         [0021]     Most medical ultrasound units operate at approximately 3-10 MHz in transcutaneous applications. Frequencies as high as 50 MHz have been used with ultrasound catheters. Lower frequencies penetrate tissue further but offer lower resolution. In one implementation, the blood-vessel locating-system  100  may use, for example, a frequency of about 8 MHz. Choosing one frequency or a narrow band of frequencies may enable a reduction in the size, complexity and cost of the blood-vessel locating-system  100 .  
         [0022]     An algorithm or method used to determine vessel location may be selected based on the layout of an array of receivers  102 . Given a linear array of receivers  102 , each receiver may provide respective data representing the magnitude of the received Doppler shift with respect to time. Regardless of whether the data is the product of a FFT or an analog signal produced by a demodulator, the data may be processed to determine the presence of Doppler shift with respect to time for each receiver (e.g., using trigonometric measures).  
         [0023]     The blood-vessel locating-system  100  preferably uses continuous wave (CW) and/or pulse wave (PW) Doppler ultrasound with a demodulation circuit having suitable analog to digital converter (ADC). The Receiver  102  is preferably dampened to reduce signal noise and design complexity.  
         [0024]      FIG. 2A  is a flow chart illustrating a blood-vessel locating-method  200  according to an embodiment of the present invention. In step  201 , a blood vessel is detected (e.g., using ultrasound, magnetic, or optical waves). Then, in step  202 , a visual indication is provided at a location that is in the vicinity of and preferably adjacent to the detected blood vessel. As a result, a medical technician is able to quickly determine where to inject a patient with a drug or medicine. If several blood vessels are detected, then a plurality of visual indications may be provided at locations that are adjacent to the respective blood vessels. Alternatively, a visual indication is provided at a location that is adjacent to the blood vessel that is determined to have the highest rate of blood flow.  
         [0025]      FIG. 2B  is a flow chart illustrating an exemplary method  210  of the blood-vessel locating-method  200 . In step  211 , ultrasound waves are transmitted into a body part (e.g., a patient&#39;s arm). In step  212 , ultrasound waves that reflect off the interior of the body are received. After the ultrasound waves are received, they are analyzed to determine the location of a blood vessel in the body part, as indicated in step  213 . In step  214 , a visual indication is provided at a location that is in the vicinity of and preferably adjacent to the detected blood vessel. In an alternative embodiment, light waves or other energy waves may be transmitted, received, and analyzed to help determine the location of a blood vessel.  
         [0026]      FIGS. 3A and 3B  are schematic diagrams depicting a frontal view and a plan view, respectively, of a strap-mounted blood-vessel locating-system  300 . The strap-mounted blood-vessel locating-system  300  includes a blood-vessel locating-system  100 - 1  and a strap  302  for mounting the locating system  100 - 1  on a patient (e.g., on a patient&#39;s arm). The strap  302  may comprise, for example, a belt, adhesive, and/or a hook-and-loop mechanism. Any suitable fastening means other than the strap  302  may alternatively be used. The blood-vessel locating-system  100 - 1  includes a plurality of light indicators  104 - 1  (e.g., light emitting diodes (LED&#39;s)). A light indicator  104 - 1  that is located closest to a detected blood vessel may emit light to indicate the location of the blood vessel.  
         [0027]     As shown in  FIG. 3B , the blood-vessel locating-system includes display devices  311  and  312 , each of which may be, for example, a liquid crystal display (LCD). The display device  311  may be used to display a numeral and/or a letter indicating the depth of a detected blood vessel, which may be, for example, between 1 and 30 mm. The display device  312  may be used to display a numeral and/or a letter indicating the blood flow rate in a detected blood vessel.  
         [0028]      FIGS. 4A and 4B  are schematic diagrams depicting a frontal view and a plan view, respectively, of a strap-mounted blood-vessel locating-system  400 . The strap-mounted blood-vessel locating-system  400  includes a blood-vessel locating-system  100 - 2  and a strap  302  for mounting the blood-vessel locating-system  100 - 2  on a patient. The system  400  includes a display device  104 - 2 . The display device  104 - 2  may be, for example, a liquid crystal display (LCD). A portion of the display device  104 - 2  that is located closest to a detected blood vessel may darken or lighten (depending on a desired implementation) to indicate the location the blood vessel. As shown in  FIG. 4B , the strap-mounted blood-vessel locating-system  400  includes display devices  311  and  312 , each of which may function as discussed above in reference to  FIG. 3B .  
         [0029]      FIG. 5  is a schematic diagram illustrating the strap-mounted blood-vessel locating-system  300  being used to indicate the location of a blood vessel  502  that is flowing through a patient&#39;s arm  501 . As shown in  FIG. 5 , the strap  302  is used to mount the locating system  100 - 1  onto the patient&#39;s arm  501 . When the locating system detects a blood vessel, the light emitter  104 - 1  emits light to indicate that the detected blood vessel  502  is located immediately below the light emitter  104 - 1 .  
         [0030]     It should be emphasized that the above-described embodiments of the present invention are merely possible examples, among others, of the implementations, setting forth a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiments of the invention without departing substantially from the principles of the invention. All such modifications and variations are intended to be included herein within the scope of the disclosure and present invention and protected by the following claims.