DEVICE AND METHOD FOR LOCATING VEINS OR ARTERIES

FIELD OF THE INVENTION

The present invention relates to a device and method for locating veins or arteries. In particular, the invention relates to a portable device for locating a vein or artery in tissue beneath the skin of a human or animal patient .

BACKGROUND OF THE INVENTION

It can sometimes be difficult for a medical care-giver to locate a patient ' s vein or artery for the purpose of drawing blood, giving blood, or giving an intravenous injection. Such injections might include injections of any medicated fluid into the vein or artery, such as simple saline solution, or complex antidotes and the like. Visual location of a vein or artery using the human eye can be particularly difficult in patients with dark-coloured skin or in children, infants or others who have particularly thick layers of fat above their veins and arteries.

Abnormal skin masses can also lead to more difficulty in locating a vein or artery under the skin mass.

US 2006/0020212 describes a portable vein locating device which includes one or more infrared illuminators for transmission of infrared light through a patient's skin, and a vein imaging module for determining the location of a vein beneath the skin by detecting the absence of backscattered infrared light. As the device is passed over a patient's skin, infrared light from the infrared illuminators penetrates through the patient's skin and is absorbed by veins under the skin but scattered by the fat and other tissues surrounding the veins. Backscattered infrared light

from the areas about the veins is detected by the vein imaging module, which includes a number of infrared light detectors, for detecting the backscattered light, and a display, for indicating to the medical caregiver the location beneath the skin of detected veins.

The present invention seeks to provide an improved device for locating veins or arteries which provides various advantages over currently known devices .

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a portable device for locating a vein or artery in tissue beneath the skin of a human or animal patient. The device comprises: an infrared emitter for transmitting infrared radiation through the skin of the patient; an infrared detector for detecting reflected infrared radiation so as to identify a vein or artery location beneath the patient's skin; an indicator for indicating the identified vein or artery location; and an opening in the device arranged to allow marking of the patient's skin at the identified vein or artery location.

The infrared detector detects infrared radiation reflected from the patient's tissue. In contrast, infrared radiation is absorbed rather than reflected by the patient's veins and/or arteries.

Thus, the device assists a care giver by providing a quick approach to find any usable vein/artery which may not be detectable via touch or visual inspection. The claimed device is particularly beneficial for those with dark skin, or having a high fat content, where standard techniques for vein/artery location are less successful . The device uses non-invasive infrared technology to locate veins or arties

in human or animal tissue. The location of a vein or artery is indicated to the user visually and/or audibly. The device has an associated location marking means for marking the location of a viable vein or artery identified by the device. This location marking means is in the form of an opening in the device at a suitable location relative to the infrared emitter/receiver that it can be used to insert a pen through to mark a vein/artery location directly onto the patient's skin. This makes it easy for a user to know exactly where to insert the needle/syringe. Alternatively, marking of veins/arteries could be used to allow a technician or surgeon to make a precision incision in a patient's skin without risking cutting through a major vein/artery and potentially causing unwanted bleeding. The device is intended for use by professionals or other caregivers, such as home carers.

Advantageously, the indicator is operable to indicate an amount of reflected infrared radiation detected by the infrared detector such that a location which reflects a reduced amount of infrared radiation may be identified as a vein or artery location.

Optionally, the opening comprises one or more of a notch, a slot and a hole. Advantageously, the opening comprises a hole for marking a point location of the identified vein or artery on the patient's skin.

Advantageously, the opening comprises an elongate slot for marking a direction of the identified vein or artery on the patient's skin. The slot may be an open slot.

Advantageously, the indicator comprises an audible indicator operable to sound when the amount of reflected infrared radiation detected by the infrared detector is below a predetermined threshold value.

Optionally, the indicator comprises a visual indicator. Advantageously, the visual indicator comprises a light emitting diode operable to illuminate when the amount of reflected infrared radiation detected by the infrared detector is below a predetermined threshold value. In one advantageous embodiment, the infrared detector comprises an array of infrared detector elements. More advantageously, the visual indicator comprises a display for displaying a spatial distribution of reflected infrared radiation- detected by the array of infrared detector elements.

In one embodiment, the device further comprises a magnifying lens for enhanced visibility of the patient's skin by a user.

According to a second aspect of the present invention, there is provided a method for locating a vein or artery in tissue beneath the skin of a human or animal patient. The method comprises : providing a portable device having an infrared emitter, an infrared detector, an indicator and an opening; moving the device across the patient's skin; transmitting infrared radiation through the patient's skin with the infrared emitter; detecting reflected infrared radiation with the infrared detector so as to identify a vein or artery location beneath the patient's skin; indicating an identified vein or artery location with the indicator; and marking the patient's skin at the identified vein or artery location by inserting a marking device through the opening.

The marking device may be a pen or the like. As for the first aspect of the present invention, the indicator may be an audio indicator such as an alarm tone, or may be a visual indicator such as an LED or two-dimensional display screen. The opening may include a hole and/or a slot.

According to a third aspect of the present invention, there is provided a method for locating a vein or artery in tissue beneath the skin of a human or animal patient. The method comprises : providing a portable device having an infrared emitter, an infrared detector, an indicator and an opening; moving the device across the patient's skin; transmitting infrared radiation through the patient's skin with the infrared emitter; detecting reflected infrared radiation with the infrared detector so as to identify a vein or artery location beneath the patient's skin; indicating an identified vein or artery location with the indicator; and injecting the patient at the identified vein or artery location by inserting a needle or syringe into the patient's skin through the opening. According to a fourth aspect of the present invention, there is provided a method for locating an area of tissue free of veins or arteries beneath the skin of a human or animal patient. The method comprises: providing a portable device having an infrared emitter, an infrared detector, an indicator and an opening; moving the device across the patient's skin; transmitting infrared radiation through the patient's skin with the infrared emitter; detecting reflected infrared radiation with the infrared detector so as to identify any vein or artery locations beneath the patient's skin; indicating any identified vein or artery location with the indicator; moving the device to an area of tissue free of veins or arteries beneath the patient's skin; and making an incision in the patient's skin in the area free of veins or arteries by inserting a cutting implement into the patient's skin through the opening.

Advantageously, the opening comprises a slot. More advantageously, the opening comprises an open slot.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 shows top and bottom perspective views of a device in accordance with a first embodiment of the present invention; and

Figure 2 shows top and bottom perspective views of a device in accordance with a second embodiment of the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Figures Ia and Ib show top and bottom perspective views respectively of a hand-held device 10 in accordance with a first embodiment of the invention. The device 10 is portable and is ergonomically designed for ease of holding by the user. The device generally approximates a pen or stylus in shape, being generally elongate and having a rounded tip 16.

The device is comprised of metallic or plastics injection-moulded parts which make it easy to manufacture, light-weight and also provide a high level of ruggedness. In particular, the device 10 will continue to function after a drop of Im onto a concrete surface. The device 10 comprises very few sub-assemblies, which makes it cheaper and easier to manufacture.

In Figures Ia and Ib, the device can be seen to have a top face 12 and a bottom face 14. The terms "top" and "bottom" used herein are relative terms which are used for ease of description of the Figures. However, it will be appreciated that the device 10 could be stored or used in an

alternative orientation such that the "top" face 12 of Figure Ia does not face substantially upwards. Thus, the terms "top" and "bottom" should not be construed to be limiting. The device 10 extends in an elongate manner between first and second ends 16 and 18 respectively. The first end 16 is _ the tip of the device 10. Between the two ends 16 and 18, the device comprises three consecutive portions 20, 22 and 24, as described below. The first portion 20 includes the first end 16. As shown in the bottom perspective view of Figure Ib, the first portion 20 comprises an infrared emitter/receiver 26. In this embodiment, the infrared emitter/receiver 26 includes two elongate arrays of emitter/receivers 26a and 26b disposed on the bottom face 14 of the device 10. The two elongate arrays of emitter/receivers 26a and 26b extend substantially along the elongate axis of the device 10. Such infrared ray technology has been used in many other medical and non-medical devices (e.g. TV remote controls, car remote locking devices) over the past 30 years. It is used in all manner of product applications and is harmless to humans/animals so is safe for human/animal use. Due to the low frequencies, the infrared technology is also very economical and draws low power from a battery. The infrared emitter/receiver 26 comprises a plurality of emitting and receiving sensors which are configured to enable depth measurement to be achieved.

As shown in Figures Ia and Ib, the first portion 20 further comprises a hole 28 and a slot 30 which each extend through the device 10 from the top face 12 to the bottom face 14. The hole 28 is a relatively small aperture which is shown as being circular in Figure 1. The hole is located

close to the infrared emitter/receiver 26 on the bottom face 14 of the device 10. The slot 30 is an elongate triangular shape which extends from first end 16 of the device 10 towards the hole 28. Thus, the slot 30 is also located close to or in the vicinity of the infrared emitter/receiver 26. It should be noted that the hole 28 lies on the lengthwise axis of the elongate slot 30. In addition, the lengthwise axis of the slot 30 extends substantially along the elongate axis of the device 10 (i.e. it extends in the same direction as each of the elongate arrays of emitter/receivers 26a and 26b) . The triangular slot 30 effectively forms an elongate arrow head pointing towards the hole 28 which identifies the vein location. The hole 28 and the slot 30 allow and assist the user to mark or guide a syringe tip to the appropriate vein or artery location as discussed further below.

The second portion 22 includes visual and/or audio indicators which are responsive to the amount of infrared radiation received by the infrared emitter/receiver 26. In Figure 1, a single visual indicator is shown on the top face 12 of the device 10 in the form of an LED 32 which illuminates when a reduced amount of radiation is detected by the infrared emitter/receiver 26. The illumination may be constant or flashing. An audible tone may also sound from a microphone (not shown) on the device 10 when a reduced amount of radiation is detected by the infrared emitter/receiver 26. The illumination may get brighter and/or the alarm tone may get louder as the device 10 gets closer to a viable vein, which is indicated by a decreasing overall amount of reflected radiation being detected by the infrared emitter/receiver 26.

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The third portion 24 includes the second end 18. The third portion 24 is essentially a handle portion to enable a user to easily grip or hold the device 10 by hand, but a user may alternatively/additionally hold the device using the second portion 22. As shown in Figure Ia, a clip 34 may optionally be provided for ease of storage of the device 10 in a pocket or the like. The third portion 24 also has a panel 36 which may be removed to insert a battery (not shown) for powering the device 10. Thus, the power source of the device 10 is a DC battery. The panel 36 may be simply clipped in and out of place without the need for specialist tool .

In use, a user holds the device 10 by hand using the second and/or third portions 22 and 24 as a handle. Being a hand-held device 10, the device 10 is easily portable by a user in a pocket or the like. The user orients the device 10 such that the bottom face 14 is placed in contact with or just above the skin of a patient. In this way, the device 10 is oriented such that infrared emitter/receiver 26 is able to transmit infrared radiation through the skin of the patient. Tissue and blood have different absorption properties with respect to infrared radiation. Thus, in effect, the emitted infrared radiation is either reflected (i.e. backscattered) by tissue under the patient's skin, or is absorbed by blood in the veins or arteries of the patient. Infrared radiation that is reflected by the patient ' s tissue is detected by the infrared emitter/receiver 26. In particular, the infrared emitter/receiver 26 is operable to detect the amount of infrared radiation that has been reflected back by the patient's tissue. Therefore, when the device 10 is

appropriately positioned above a vein or artery, there is relatively less infrared reflected infrared radiation detected by the infrared emitter/receiver 26 than when the device 10 is positioned above tissue only. If the detected amount of reflected infrared radiation is less than a predetermined threshold value, the LED 32 is operable to illuminate and an audible tone may also sound so as to indicate to the user a likely position of a vein or artery of the patient . Having determined the point position of a vein or artery, the user may use a marking device (e.g. a pen) to mark the patient's skin at the appropriate point location. In particular, a pen may be inserted from above (i.e. from the top face 12 towards the bottom face 14) into the hole 28 to draw a point mark on the patient's skin. Thus, the hole 28 enables the patient's skin to be marked at a suitable point location for inserting a syringe/needle into a vein or artery.

Having identified a point location of a vein or artery, the device 10 may also be used to find the direction of the vein or artery beneath the patient's skin. This is accomplished by moving the device 10 across the patient's skin in the region of the identified vein location point. The device should be moved in a direction indicated by the arrow X in Figure Ia. In particular, the device should be moved in a direction corresponding to the primary axis of the elongate slot 30. If the LED 32 stops flashing, it is likely that the device 10 is being moved in a direction transverse to the direction of the vein or artery. In contrast, if the LED remains illuminated, it is likely that the device 10 is being moved in a direction along the identified vein or artery. In this case, the user may use

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the pen to mark the vein or artery direction on the patient's skin. In particular, the pen may be inserted from above (i.e. from the top face 12 towards the bottom face 14) into the slot 30 to draw a directional mark on the patient's skin.

Having marked the point and/or directional location of the vein or artery, the device 10 may then be put to one side and a needle or syringe may be inserted into the identified vein or artery of the patient by making use of the marks on the skin.

Alternatively, a mark need not be drawn. Instead, once the user is confident of the location of a vein or artery, the needle or syringe may be inserted directly through the hole 28 or the slot 30 of the device 10 and into the patient's skin. In other words, the hole 28 and/or the slot 30 are arranged to guide a syringe needle to the targeted vein location.

A further embodiment of the device of the present invention is shown in the top and bottom perspective views in Figure 2a and 2b respectively. Similar reference numerals are used in Figure 2 as were used in Figure 1. Differences between the two embodiments are described below.

The slot 30 in Figure 2 is an open slot. In other words, the slot 30 is open at the tip end 16 of the device

10. This enables a pen or cutting instrument to be inserted into the slot 30 more easily by the user.

As in the first embodiment, the second portion 22 of the second embodiment includes visual and/or audio indicators which are responsive to the amount of infrared radiation received by the infrared emitter/receiver 26. In particular, the same audible alarm may be provided to sound

when a reduced overall amount of radiation is detected by the infrared emitter/receiver 26. However, rather than the LED 32 of Figure 1, the embodiment of Figure 2 comprises a display 38 in the form of a liquid crystal display (LCD) . A control PCB is also provided within the device. The control PCB receives and processes signals from the infrared emitter/receiver 26 so as to provide associated image data to be displayed on the display 38. Thus, the display 38 provides a two-dimensional display of reflected infrared radiation. In the image shown on the display 38 there is therefore a contrast between the patient ' s tissue areas and any veins/arteries. Since a two-dimensional representation is provided, the display 38 enables the vein/artery direction to be ascertained. In other words, the display 38 depicts both vein/artery location and vein/artery direction in one simple image. As for the previous ^• embodiment , the vein/artery location may be marked on the patient ' s skin by inserting a pen through hole 28, and the vein/artery direction may be marked on the patient's skin by inserting a pen through slot 30 when the vein/artery on the display is aligned with the slot 30. Also, using the display 38, the user can view the physical shape of an identified vein/artery in terms of either its diameter or flow rate, and can thereby determine whether the particular vein/artery is suitable for needle puncture. Alternatively, a technician or surgeon could make a precision incision into a patient's skin by inserting a cutting instrument through the slot 30 when the display 38 indicates that there is not a major vein/artery in the vicinity. This would prevent the possibility of unwanted bleeding of the patient due to the incision. The display 38 can be either color or monochrome (e.g. black and white) .

An on/off switch 40 is also provided on the top face 12 of the second portion 22 of the device 10 in Figure 2a.

In Figure 2, the third portion 24 is formed as a ring 42 with a central aperture 44 for receiving a magnifying glass or lens (not shown) . When inserted, the magnifying glass enables the user to magnify any skin type so as to more clearly see the skin surface, particularly in difficult lighting conditions. In other words, the magnifying lens provides improved visibility of the patient's skin for the user.

There are many potential applications for the device of the present invention in terms of location of veins/arteries beneath the surface of human/animal tissue. For example, it is contemplated that the device could be used by fire fighters, paramedics, students, technicians, phlebotomists, nurses, doctors, veterinarians, and so on. Some such applications of the device are described further below.

Veterinary applications of the device are envisaged when the patient is an animal. In such cases, it may be necessary for the veterinarian to shave the animal ' s fur or hair before using the device. Alternatively, constructional changes could be incorporated to suit the presence of furry tissue . A clinical/hospital variant is also envisaged. Such a variant would include the two-dimensional display feature as described above with reference to Figure 2. This variant would also include an interface for acceptance of invasive surgical devices. For example, differently shaped openings may be provided in addition to or instead of the hole 28 and the slot 30 described above. A data export port could also be included to enable the display to be shown on a separate

display device. This would enable the display to be larger in cases where fine resolution is required.

A military variant is also contemplated. This would be similar to the hospital version, but with more rugged construction.

A paediatric variant is also envisaged. Such a device would be similar to those described above, but with a higher degree of precision.

Although preferred embodiments of the invention have been described, it is to be understood that these are by way of example only and that various modifications may be contemplated.