Patent Application
20050119546
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'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.
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.
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.
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
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.
In one embodiment, the transmitter 101 transmits ultrasound waves which reflect off the interior of a body part (e.g., a patient'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.
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.
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.
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.
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.
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.
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.
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).
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.
As shown in
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.
| Number | Date | Country | |
|---|---|---|---|
| 0027185 A1 | Feb 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60399982 | Jul 2002 | US |
