Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
1998-08-24
2001-01-23
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
C600S321000, C600S407000, C600S473000, C600S476000, C250S226000, C250S341800
Reexamination Certificate
active
06178340
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to instruments for infrared imaging, and in particular, to a system for imaging the vascular network in order to study it and to enable safe and accurate puncture of the veins by a hypodermic needle.
BACKGROUND OF THE INVENTION
Although insertion of needles into the human vascular network is commonly considered by medical professionals to be one of the most routine and easily performed activities, such a “simple” technique is traumatic, painful and dangerous for the patient. Erroneous attempts to penetrate the arterial-venous system are not rare in medical practice, causing numerous injuries to the patient.
Penetration of the vascular network is necessary for two main reasons: extraction of blood for laboratory analysis or delivery of fluids and/or different agents of contrast used in angiographic techniques. The consequences due to missed puncture of the vein include the need for repeated puncture causing the patient to feel further threatened, discomfort, pain, sweat, fear, and in difficult patients loss of cooperation while performing the puncture. Extravasation of agents of contrast due to a missed vein puncture can cause terrible pain, sweat and necrosis of the place of puncture in some cases.
Certain patient groups are known to be more difficult to properly puncture. The classical groups include: overweight people, young women, infants (especially premature babies) and young children, dark-skinned people and people in shock.
Apparatus for visualization of the subcutaneous vessels are known, and an example of current imaging technology is disclosed in U.S. Pat. No. 4,817,612 to Pennypacker et al, in which a two-dimensional vein location system is described. Working under a two-dimensional image causes more damage than working without an imager. Because there is no depth sensation, the access of the needle in relation to the arm will be incorrect, necessitating repetitive puncturing.
U.S. Pat. No. 5,519,208 to Esparza et al discloses a two-dimensional vein location system which requires the attachment of an LED to the tip of the needle. A light of this sort will be emitted tangentially, causing bad scattering of light on the area of inspection in relation to the optical axis of the human eye. If the infrared light comes from the wrong direction the light will not be able to provide the proper information. Infrared light which is applied to the human body must be scattered uniformly to distinguish the fine details of the veins before any electronic manipulation of the image has been done. Improper illumination cannot be corrected with the use of an image processor, since information which does not exist on the image because it has not been properly illuminated cannot be enhanced by any image processor. In addition the attachment of an LED to the tip of the needle necessitates providing a power source to feed the LED. Currently, disposable needles are used almost exclusively, making this design impractical.
U.S. Pat. No. 5,608,210 to Esparza et al mentions the visual sensation of three dimensions, although the apparatus described therein is unwieldy, and is designed to be worn on the head. This demands that the health care providers change their style of working. Although this method has been used in the indirect ophthalmoscope for more than 50 years, the modern instrument reaches a weight of only 300-350 grams. Attempts by many companies to introduce a more sophisticated head-worn opthalmoscope with a video system have resulted in failures due to the weight and the instability of the image due to head movement. These obstacles apply to a head-worn vascular imager as well. Other attempts at head-worn imagers include a military infrared viewer mounted on the head or worn on goggles. This device was rejected because the weight did not allow maintenance of a constant image in accordance with the optical axis of the eye.
Although the Esparza '210 patent does provide a certain three-dimensional sensation, the effect is actually more theoretical than practical as the distance from the eyes of the user to the subject must be fixed, otherwise the cameras need to be refocussed, so that both cameras are tilted to a convergent point on the subject. If the distance from the eyes of the user to the subject is reduced the convergent point is crossed and the three-dimensional effect is lost. In order to hold a video screen (or two) in front of the user's eyes, optical lenses are required with a refractive power which is determined so as to correct the shorter distance accepted by the human eye. This would cause discomfort to the user upon removal of the apparatus until the eyes would readjust to their normal focus. This discomfort could include dizziness, nausea and headaches.
Therefore, it would be desirable to provide an imager with proper illumination which would provide a clear three-dimensional image in real time so as to improve the success rate of health care providers in penetrating the vascular system. This would allow the patient to both feel at ease and comfortable, thereby lowering the stress level of patients who fear an inaccurate puncture and also lowering the incidence of medical complications resulting from an inaccurate puncture.
SUMMARY OF THE INVENTION
Accordingly, it is a principal object of the present invention to overcome the problems associated with the prior art and provide a novel three-dimensional infrared imager with a proper illumination source for study of the vascular network so as to cause blood vessels to be visualized for accurate subcutaneous puncture during insertion of a hypodermic needle. This apparatus would lower the fear of venous puncture and lower the incidence of medical complications associated with inaccurate puncture.
The invention is based on use of knowledge associated with the human vision system, in which both eyes are receptors of information transmitted by visible light. The rays of light are collected by the cornea and reach the lens of the eye which sends them to a common focussed point on the retina called the macula. The macula is the most sensitive part of the retina, and is responsible for the acute sight due to the largest concentration therein of the photoreceptors. The photoreceptors are connected with the neurons which convert light energy into electro-chemical pulses, which are transmitted by the nerve fiber layer through the optic nerve to the visual center located at the back of the brain. The collection of information by both eyes is transformed by the brain into a three-dimensional perception of the external world, and such perception relates to the visible portion of the light spectrum. Light wavelengths above or below the visible zone are not sensed by the eyes. Therefore, the use of sensors sensitive to infrared radiation and conversion to a visible image improves the human vision capability beyond its normal limitations.
The present invention uses the properties of near infrared light as it is absorbed and reflected by the human body allowing the user to visualize the tissues a few millimeters in depth from the skin's surface. The use of infrared light permits the manipulation of the acquired information to a grade of sensed visualization, which is impossible to reach with visible light.
The present invention is designed to be user friendly, allowing the health care professional to work in his usual manner. The invention imitates the human three-dimensional perception by use of a stereoscopic infrared viewer. A double image is superimposed on the viewer and the user wears blue-red glasses to create the three-dimensional image from the double image on the viewer. With the depth perception provided by the three-dimensional image, the user can accurately penetrate the vein on the initial attempt, causing the patient to be at ease.
In a preferred embodiment of the invention, a liquid crystal display (LCD) mounted in a frame is provided on the upper surface of the apparatus. Sensitive, charge-coupled devices are provided which develop images and
Edward Langer, Pat. Atty.
Lateef Marvin M.
Lin Jeoyuh
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