Patent Grant
8167813
The present invention generally relates to medical care. More particularly, the present invention relates to systems and methods for locating a blood vessel.
Determining the location of a blood vessel is a common medical procedure. Historically however, the systems and methods that medical practitioners use for locating blood vessels have been imprecise, cumbersome, and/or expensive.
For example, one common conventional method for locating a blood vessel involves restricting blood flow to a patient's arm and visually identifying a blood vessel. While this conventional method is widely used and inexpensive, it suffers from several problems. For instance, even in ideal conditions, determining the precise location of a blood vessel using this method may be difficult. Also, the conventional method is invasive, causing a patient discomfort as their arm is being restricted. The procedure may be further complicated with patients who are experiencing trauma, or with patients who have darker or thicker skin.
Rather than using a conventional manual method, a medical practitioner may use a device for locating a blood vessel. However, conventional devices that attempt to locate blood vessels may suffer from inaccuracy, invasiveness, high cost, and relative impracticality. And some devices may only work on certain patients.
Thus a need exists for an accurate, convenient, and inexpensive device for locating blood vessels.
Embodiments of the present invention disclosed herein provide systems and methods for locating a blood vessel.
One embodiment of the invention is a system comprising a temperature sensor operable to take at least two temperature measures of at least two points on a surface of a skin. The embodiment further comprises a processor in communication with the temperature sensor and configured to receive a first temperature measure from the temperature sensor, receive a second temperature measure from the temperature sensor, determine a differential between the first temperature measure and the second temperature measure, and generate an output signal indicating the presence of a blood vessel if the differential exceeds a threshold. The embodiment may further comprise an indicator configured to receive the output signal and, in response, indicate the presence of the blood vessel.
Another embodiment of the invention implements a method comprising receiving a first temperature measure associated with a first point on a surface of a skin, receiving a second temperature measure associated with a second point on the surface of the skin, and determining a differential between the first temperature measure and the second temperature measure. The method further comprises generating an output signal indicating the presence of a blood vessel if the differential exceeds a threshold. In another embodiment, a computer-readable medium (such as, for example random access memory or a computer disk) comprises code for carrying out such a method.
Further details and advantages of embodiments of the invention are set forth below.
These and other features, aspects, and advantages of the invention are better understood when the following Detailed Description is read with reference to the accompanying drawings, wherein:
Embodiments of the present invention provide systems and methods for locating a blood vessel. In one illustrative embodiment, a blood vessel locator is embodied in a handheld device that includes a temperature sensor. A medical practitioner holds the blood vessel locator on or near the patient's skin, for example, on the skin of the patient's arm. As the medical practitioner moves the locator across the patient's arm, the temperature sensor takes temperature readings at points on the surface of the skin and outputs these temperature readings to a processor housed in the device. Since the temperature of the skin above a blood vessel may be different from the temperature of skin below which no blood vessel is present, a blood vessel may be located by locating a temperature differential between two points on the surface of a skin. The processor continually calculates the differences in skin temperature between the current reading and the previous reading or readings.
When the processor determines that a difference in temperature exists, the processor compares the observed difference between two temperature readings to a pre-determined threshold stored in memory. If the difference exceeds the pre-determined threshold, a blood vessel may be present, and the device provides an indication that a blood vessel has been located. For instance, the device may light a light emitting diode (LED), vibrate the housing, beep, or provide some other indication. The device may also mark the skin with a small ink dot at the location of a blood vessel so the medical practitioner can easily find the spot after the locator has been moved away in preparation for inserting a needle into the blood vessel or performing some other procedure.
This example is given to introduce the reader to the general subject matter discussed. The invention is not limited to this example. Below, an illustrative blood vessel locator is introduced. Then, example blood vessel locators and methods to locate a blood vessel are described.
Referring now to the drawings in which like numerals indicate like elements throughout the several figures,
In one embodiment, the blood vessel locator 102 shown in
In other embodiments, the blood vessel locator 102 may be moved in other directions. For instance, the locator 102 may be moved in a circular pattern or laterally and then longitudinally. In other embodiments, the surface of the skin 106 may be moved under the blood vessel locator 102, while the locator 102 remains in a stationary position. For instance, the locator 102 may be fixed in a stand (not shown). While the embodiment shown in
The blood vessel locator 102 also includes one or more temperature sensor(s) (not shown), which are at least partially contained within the housing. As the blood vessel locator 102 moves across the surface of the skin 106, the temperature sensor(s) detect the temperature of the surface of the skin 106. The temperature sensor(s) may be sensitive to a limited range of temperatures. The temperature sensor(s) may provide continuous temperature data when sensing temperatures within this range. The temperature sensor(s) may be located so that the actual sensor passes through an opening on the bottom surface of the housing of the locator 102, and may detect the temperature of the surface of the skin through direct contact. Alternatively, the sensor(s) may be attached to the outside of the housing. Some embodiments utilize one or more temperature sensor(s) that are configured to sense the temperature of the skin without direct contact.
The blood vessel locator 102 shown in
In one embodiment, once the processor receives at least two temperature measures, it calculates a differential between the two measures. The processor may be programmed to ignore temperature measures within a range of the first temperature measure but may calculate a differential of measures. If the processor determines that the temperature differential indicates the presence of a blood vessel, the blood vessel locator 102 provides some indication that a blood vessel is present. For instance, the blood vessel locator 102 shown in
In other embodiments, the blood vessel locator 102 may activate other types of indicators or a combination of types of indicators to indicate the presence of a blood vessel. For example, in one embodiment, the blood vessel locator 102 comprises an actuator, such as an eccentric rotating mass (ERM) motor, for outputting haptic effects to a user of the locator 102. Such a device may vibrate when a blood vessel is located or vibrate at an increasing frequency as a blood vessel is approached and a decreasing frequency as the locator 102 moves away from the blood vessel.
Another embodiment comprises a speaker contained within the blood vessel locator 102. The speaker provides an audio cue as to the presence of a blood vessel. In one alternate embodiment of the present invention, the blood vessel locator 102 comprises a liquid crystal diode (LCD) display, configured to provide a thermal picture of the surface of the skin 106 and thereby indicate the location or locations of blood vessels.
The temperature sensor 204 may utilize any of a number of different temperature measuring technologies. For example, the temperature sensor 204 may comprise a thermocouple contact sensor. In such embodiments, the temperature sensor 204 may detect the temperature of the surface of the skin through direct contact with the skin. In other embodiments of the invention, the temperature sensor 204 may be a different type of temperature sensor. For example, the temperature sensor 204 may be an infrared thermometer, capable of detecting the temperature of the skin without direct skin contact.
In embodiments of the invention requiring direct contact with the skin for temperature measurement, the blood vessel locator 202 may comprise an additional disposable component. For example, the disposable component may comprise a sterile plastic sleeve, capable of covering the temperature sensor 204. The additional disposable component may help to ensure good hygiene and may also help to shield the device from contamination.
While detection of blood vessels using embodiments of the present invention may be possible without any preparation, temperature differentials may in some circumstances be more easily detected by the temperature sensor 204 if the surface of the skin is warmed or cooled before the temperature measure is taken. For example, a practitioner may warm a patient's arm by soaking it with warm water before using the blood vessel locator 202.
Referring still to
The processor 206 may comprise a computer-readable medium, such as a random access memory (RAM) (not shown) coupled to the processor. The processor 206 may execute computer-executable program instructions stored in memory. Such processors can include one or more microprocessors, ASICs, and state machines. Such processors may further comprise programmable electronic devices such as PLCs, programmable interrupt controllers (PICs), programmable logic devices (PLDs), programmable read-only memories (PROMs), electronically programmable read-only memories (EPROMs or EEPROMs), or other similar devices.
Such processors include, or can be in communication with, media, for example, which stores instructions that, when executed by the processor, cause the processor to perform the steps described herein. Embodiments of computer-readable media include, but are not limited to, an electronic, optical, magnetic, or other storage or transmission device capable of providing a processor with computer-readable instructions. Other examples of suitable media include, but are not limited to, a floppy disk, CD-ROM, DVD, magnetic disk, memory chip, ROM, RAM, an ASIC, a configured processor, all optical media, all magnetic tape or other magnetic media, or any other medium from which a computer processor can read instructions. Also, various other forms of computer-readable media can transmit or carry instructions to a computer, including a router, private or public network, or other transmission device or channel, both wired and wireless. The instructions can comprise code from any suitable computer-programming language, including, for example, C, C+, C++, Visual Basic, Java, Python, and JavaScript.
The processor 206 may be configured to receive multiple temperature measures from a temperature sensor 204. In other embodiments, the processor 206 may be configured to receive one or more temperature measures from multiple temperature sensors. In the embodiment shown in
When the processor 206 receives the temperature measure from the temperature sensor 204, the processor 206 may compare the measure to a previously-received temperature measure or to some other data stored in memory (not shown). For instance, the processor 206 may be configured to determine a differential between a first temperature measure and a second temperature measure. The processor 206 may be further configured to determine a differential between a second temperature measure and a third temperature measure. In other embodiments, the processor 206 may instead store a reference or calibration temperature measure and compare temperature measures received from the temperature sensor 204 to the reference or calibration temperature measure.
Once the processor has determined the differential, the processor 206 may compare the differential to a threshold. If the differential meets or exceeds the threshold, then the processor 206 may be configured to generate an output signal indicating the presence of a blood vessel.
In some embodiments, if the processor 206 determines that a differential between two temperature measures or between a temperature measure and a calibration or reference measure exceeds a threshold, the processor 206 generates an output signal. The threshold, for example, may be any differential amount that is indicative of the presence of a blood vessel. For instance, in one embodiment, the threshold is set at 0.5 degrees Fahrenheit. The differential may be predetermined as in the example described, or a medical practitioner may configure the differential threshold during operation of the blood vessel locator 202 to account for variations in patients or environments.
Also, in some embodiments, if the processor 206 determines that a differential between two temperature measures does not exceed a threshold, the processor 206 does not generate an output signal. In other embodiments, if the processor 206 determines a differential between two temperature measures does not exceed a threshold, the processor 206 generates a signal indicating the absence of a blood vessel.
In some embodiments, the processor 206 may determine a direction or axis of a blood vessel. Two or more differentials exceeding the threshold may indicate the direction of the blood vessel. For example, a sequence or succession of differentials in excess of a threshold may indicate the direction of a blood vessel. When a direction of a blood vessel is determined, the processor 206 may generate an output signal indicating the direction.
The blood vessel locating device 202 shown in
In some embodiments, the indicator 208 may comprise a visual indicator. Visual indicators may include one or more lights, or a LCD display. For example, the indicator 208 may comprise a single red LED. When the indicator 208 receives a signal from the processor 206 indicating the presence of a blood vessel, the red LED will be activated.
The indicator 208 may also comprise an audio indicator, for example, a speaker. In such embodiments, the indicator 208 may emit a tone when it receives a signal from the processor 206 indicating the presence of a blood vessel.
In some embodiments of the present invention, the blood vessel locator 202 may comprise a marker (not shown). In one such embodiment, the marker is configured to generate a mark on the surface of the skin over the located blood vessel by, for instance, spraying one or more drops of ink on the skin. Multiple drops may indicate the direction or axis of the blood vessel. Then, when the medical practitioner moves the blood vessel locator 202 away from the skin in order to perform a medical procedure, the mark or marks are visible on the skin.
In another embodiment, the marker comprises a light. In one example, the marker may be configured to illuminate the location of the blood vessel on the surface of the skin with a small beam of light. In another example, the light may indicate the direction or axis of the blood vessel. In yet another embodiment, the marker is configured to leave one or more small, temporary indentations on the surface of the skin where the blood vessel is located.
The blood vessel locator 202 may include additional features to enhance its convenience for practitioners. For example, in some embodiments of the blood vessel locator 202, the marker may be used as a flashlight.
In other embodiments, the blood vessel locating device 202 may include a guide for directing medical devices to the located blood vessel. For example, the blood vessel locating device 202 may comprise a slot (not shown) in which or through which an intravenous needle can be directed. The slot is configured so that it directs the needle to the location of the blood vessel as indicated by the blood vessel locator 202. These additional features are illustrative and not exhaustive; other features may also be incorporated into various embodiments of the present invention.
The two or more temperature sensors 304 of the blood vessel locator 302 may be configured to detect and output temperature measures substantially simultaneously. For example, each temperature sensor 304a and 304b may be activated at the same time. In other embodiments, the temperature sensors 304 may output temperature measures at different times.
In embodiments of the invention with multiple temperature sensors 304, the sensors may be substantially aligned. For example, in an embodiment comprising three or more temperature sensors, some or all of the temperature sensors may be placed in a linear arrangement. In such embodiments, the temperature sensors 304 may be configured to output temperature measures from adjacent surfaces of the skin. As such, the three temperature measures may originate from three points in a linear alignment on the surface of the skin. Such embodiments may provide faster detection of a blood vessel than an embodiment using fewer sensors.
In other embodiments of the invention with multiple temperature sensors, the temperature sensors may be arranged in an array. The array of temperature sensors may then be capable of capturing a thermal picture of an area of a patient's skin. In areas where the temperature differential exceeds a threshold, the thermal picture may then be used to locate the presence of a blood vessel within the boundary of the picture.
The location of the temperature sensors 304 may be impacted by the type of patient on which the blood vessel locator 302 is to be used. For instance, in order to locate the blood vessels of a child, the temperature sensors 304a and 304b may be aligned more closely together than they would be to locate the blood vessels of an adult. For example, the temperature sensors may be aligned closely together such that each sensor may simultaneously contact the surface of a smaller arm.
The location of the temperature sensors 304 may be fixed in the device. In other embodiments of the invention with multiple temperature sensors, a medical practitioner may manipulate the configuration of the temperature sensors to accommodate individual patients.
In some embodiments of the present invention, the blood vessel locator 302 comprises two or more indicators, such as indicators 308a and 308b shown in
In some embodiments, the blood vessel locating device 302 also comprises an actuator 310. The actuator 310 is configured to provide a haptic effect, such as a vibrotactile effect to a user of the blood vessel locator 302. Further embodiments of the blood vessel locator 302 may comprise a plurality of actuators.
The actuator 310 may be configured to receive the output signal from the processor 306 and provide a haptic effect in response to the output signal. In some embodiments the haptic effect comprises a vibrotactile effect. For example, the actuator 310 may vibrate the housing of the blood vessel locator 302 in response to an output signal indicating the presence of a blood vessel. The actuator 310 may comprise any number of commercially available actuators, such as eccentric rotating mass (ERM) motors, voice coils, linear actuators, moving magnet actuators, piezoelectric actuators, pneumatic actuators, etc.
In step 404, a second temperature measure is received by the processor from a temperature sensor. In some embodiments of the invention, a processor can receive the first temperature measure 402 and the second temperature measure 404 as a digital signal. In one embodiment, the first temperature measure and the second temperature measure are received from the same temperature sensor. In other embodiments, the first temperature measure and the second temperature measure may be received from different temperature sensors. Further, in some such embodiments, step 402 and step 404 may occur substantially simultaneously.
In step 406, the processor determines a differential between the first temperature measure and the second temperature measure. For example, if the first temperature measure is 97.0 degrees Fahrenheit, and the second temperature measure is 97.7 degrees Fahrenheit, the temperature differential is 0.7 degrees Fahrenheit. In other embodiments, a processor may determine the differential between the second temperature measure and the third temperature measure.
In step 408, the processor determines whether a blood vessel is present by comparing the differential with a threshold. In some embodiments, the threshold value may be predefined. In other embodiments, the threshold may be specified by a medical practitioner or determined during a calibration process.
If the differential exceeds the threshold, the processor generates an output signal 410. For example, the threshold may be 0.3 degrees Fahrenheit. If the temperature differential between the first temperature measure and the second temperature measure is 0.4 degrees Fahrenheit, then the processor determines that a blood vessel is present and generates an output signal 410. The processor may send the output signal to one or more indicators, including, for example, visual, auditory, and haptic indicators.
In the embodiment of
In step 504, a subsequent temperature measure is received by a processor from a temperature sensor. In one embodiment, the subsequent temperature measure is from a point on the surface of the skin adjacent to the first calibration temperature measure. In other embodiments, the subsequent temperature measure may be from a point located nonadjacent to the first calibration point.
In step 506, the processor determines a differential between the first calibration temperature measure and the subsequent temperature measure.
In step 508, the processor determines whether a blood vessel is present by comparing the differential between the temperature measures with a threshold. In some embodiments, the threshold value may be predefined. In other embodiments, the threshold may be specified by a medical practitioner or determined during a calibration process.
If the differential exceeds the threshold, the processor generates an output signal 510. The processor may output this signal to one or more indicators, including, for example, visual, auditory, and haptic indicators.
If the differential does not exceed a threshold, the process shown continues by receiving a new subsequent temperature measure 504. The new subsequent temperature measure may originate from a third point on the surface of the skin. The processor then determines a new differential between the calibration temperature measure and the new subsequent temperature measure 506. If the processor determines the new differential exceeds a threshold 508, the processor will generate an output signal indicating the presence of a blood vessel 510.
Embodiments of the present invention provide various advantages over conventional systems and methods for locating blood vessels. For instance some embodiments allow medical practitioners to identify blood vessels in patients having varying skin tones and skin thickness, a task that may be difficult with conventional systems and methods. Further, some embodiments of the present invention are substantially less expensive than conventional devices for locating blood vessels. And embodiments of the present invention may be easier to use and less invasive, facilitating a higher level of care from the medical practitioner and less trauma for the patient.
The foregoing description of embodiments of the invention has been presented only for the purpose of illustration and description and is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications and adaptations thereof will be apparent to those skilled in the art without departing from the spirit and scope of the present invention.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3618070 | Kagan | Nov 1971 | A |
| 3911416 | Feder | Oct 1975 | A |
| 4028502 | Moricca et al. | Jun 1977 | A |
| 4227319 | Guy et al. | Oct 1980 | A |
| 4262549 | Schwellenbach | Apr 1981 | A |
| 4278920 | Ruoff, Jr. | Jul 1981 | A |
| 4333070 | Barnes | Jun 1982 | A |
| 4352091 | Yamasaki | Sep 1982 | A |
| 4421953 | Zielinski | Dec 1983 | A |
| 4436188 | Jones | Mar 1984 | A |
| 4464117 | Foerst | Aug 1984 | A |
| 4484191 | Vavra | Nov 1984 | A |
| 4581972 | Hoshino | Apr 1986 | A |
| 4603284 | Perzley | Jul 1986 | A |
| 4794392 | Selinko | Dec 1988 | A |
| 4823634 | Culver | Apr 1989 | A |
| 4853674 | Kiss | Aug 1989 | A |
| 4918438 | Yamasaki | Apr 1990 | A |
| 4931765 | Rollins et al. | Jun 1990 | A |
| 4964004 | Barker | Oct 1990 | A |
| 5003984 | Muraki et al. | Apr 1991 | A |
| 5117449 | Metroka et al. | May 1992 | A |
| 5165897 | Johnson | Nov 1992 | A |
| 5175459 | Danial et al. | Dec 1992 | A |
| 5189389 | DeLuca et al. | Feb 1993 | A |
| 5205293 | Ito et al. | Apr 1993 | A |
| 5283970 | Aigner | Feb 1994 | A |
| 5366376 | Copperman et al. | Nov 1994 | A |
| 5368484 | Copperman et al. | Nov 1994 | A |
| 5414337 | Schuler | May 1995 | A |
| 5436622 | Gutman et al. | Jul 1995 | A |
| 5437607 | Taylor | Aug 1995 | A |
| 5459382 | Jacobus et al. | Oct 1995 | A |
| 5482051 | Reddy et al. | Jan 1996 | A |
| 5489812 | Furuhata et al. | Feb 1996 | A |
| 5506605 | Paley | Apr 1996 | A |
| 5508688 | Mochizuki | Apr 1996 | A |
| 5575761 | Hajianpour | Nov 1996 | A |
| 5619181 | Murray | Apr 1997 | A |
| 5625576 | Massie et al. | Apr 1997 | A |
| 5642413 | Little | Jun 1997 | A |
| 5646589 | Murray et al. | Jul 1997 | A |
| 5666473 | Wallace | Sep 1997 | A |
| 5692956 | Rifkin | Dec 1997 | A |
| 5696497 | Mottier et al. | Dec 1997 | A |
| 5729589 | Samson | Mar 1998 | A |
| 5754096 | Muto et al. | May 1998 | A |
| 5757280 | Motohashi | May 1998 | A |
| 5764751 | Konishi | Jun 1998 | A |
| 5767787 | Kudoh et al. | Jun 1998 | A |
| 5816823 | Naimark et al. | Oct 1998 | A |
| 5844392 | Peurach et al. | Dec 1998 | A |
| 5844498 | Ide | Dec 1998 | A |
| 5867796 | Inutsuka | Feb 1999 | A |
| 5873024 | Suzuki | Feb 1999 | A |
| 5887995 | Holehan | Mar 1999 | A |
| 5889670 | Schuler et al. | Mar 1999 | A |
| 5917906 | Thornton | Jun 1999 | A |
| 5955964 | Tada | Sep 1999 | A |
| 5956484 | Rosenberg et al. | Sep 1999 | A |
| 5966655 | Hardouin | Oct 1999 | A |
| 5973689 | Gallery | Oct 1999 | A |
| 5988902 | Holehan | Nov 1999 | A |
| 6014572 | Takahashi | Jan 2000 | A |
| 6046726 | Keyson | Apr 2000 | A |
| 6091321 | Karell | Jul 2000 | A |
| 6113459 | Nammoto | Sep 2000 | A |
| 6118979 | Powell | Sep 2000 | A |
| 6131097 | Peurach et al. | Oct 2000 | A |
| 6175721 | Hayato | Jan 2001 | B1 |
| 6218958 | Eichstaedt et al. | Apr 2001 | B1 |
| 6218966 | Goodwin et al. | Apr 2001 | B1 |
| 6272319 | Narusawa | Aug 2001 | B1 |
| 6300938 | Culver | Oct 2001 | B1 |
| 6307465 | Kayama et al. | Oct 2001 | B1 |
| 6373463 | Beeks | Apr 2002 | B1 |
| 6374255 | Peurach et al. | Apr 2002 | B1 |
| 6418323 | Bright et al. | Jul 2002 | B1 |
| 6424251 | Byrne | Jul 2002 | B1 |
| 6433771 | Yocum et al. | Aug 2002 | B1 |
| 6448977 | Braun et al. | Sep 2002 | B1 |
| 6464646 | Shalom et al. | Oct 2002 | B1 |
| 6563487 | Martin et al. | May 2003 | B2 |
| 6574489 | Uriya | Jun 2003 | B1 |
| 6650338 | Kolarov et al. | Nov 2003 | B1 |
| 6686901 | Rosenberg | Feb 2004 | B2 |
| 6819312 | Fish | Nov 2004 | B2 |
| 6864877 | Braun et al. | Mar 2005 | B2 |
| 20020145512 | Sleichter, III et al. | Oct 2002 | A1 |
| 20020149561 | Fukumoto et al. | Oct 2002 | A1 |
| 20030030619 | Martin et al. | Feb 2003 | A1 |
| 20030090460 | Schena et al. | May 2003 | A1 |
| 20030122658 | Takahashi | Jul 2003 | A1 |
| 20030169151 | Ebling et al. | Sep 2003 | A1 |
| 20030188594 | Levin et al. | Oct 2003 | A1 |
| 20030222766 | Rollins et al. | Dec 2003 | A1 |
| 20040014484 | Kawashima | Jan 2004 | A1 |
| 20040056840 | Goldenberg et al. | Mar 2004 | A1 |
| 20040152991 | Pompei | Aug 2004 | A1 |
| 20050065451 | Pompei et al. | Mar 2005 | A1 |
| 20050093847 | Altkorn et al. | May 2005 | A1 |
| 20050109145 | Levin et al. | May 2005 | A1 |
| 20050162383 | Rosenberg | Jul 2005 | A1 |
| 20060020212 | Xu et al. | Jan 2006 | A1 |
| 20060253005 | Drinan et al. | Nov 2006 | A1 |
| Number | Date | Country |
|---|---|---|
| 10 2004 001931 | Aug 2005 | DE |
| WO 9520787 | Aug 1995 | WO |
| WO 9718546 | May 1997 | WO |
| WO 9948420 | Sep 1999 | WO |
| WO 0191100 | Nov 2001 | WO |
| WO 2007006134 | Jan 2007 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20080287824 A1 | Nov 2008 | US |
