Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
2001-04-20
2003-01-07
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
C600S344000, C600S322000
Reexamination Certificate
active
06505061
ABSTRACT:
FIELD OF THE INVENTION
The present invention is generally directed to photoplethysmographic measurement instruments, and more specifically to clip-type pulse oximetry sensors which attach to patient appendages.
BACKGROUND OF THE INVENTION
A common technique used to monitor blood oxygen levels is pulse oximetry. In this regard, it is known that the light transmissivity and color of blood is a function of the oxygen saturation of the heme in the blood's hemoglobin. For example, heme that is saturated with oxygen appears bright red because saturated heme is relatively permeable to red light. In contrast, heme that is deoxygenated appears dark and bluish as it is less permeable to red light. A pulse oximeter system measures the oxygen content of arterial blood by first illuminating the blood with red and infrared radiation and determining the corresponding amounts of red and infrared radiation that are absorbed by the heme in the blood. In turn, such light absorption amounts may be employed in conjunction with known calibration information to determine blood oxygen levels.
Pulse oximetry sensors generally include one or more light emitters, a detector, and a means for holding the emitter(s) and detector in contact with a patient's tissue so that an optical path is established through the tissue. There are various means for holding the emitter(s)/detector in contact to a patient's tissue; however, two common types are flexible and clip-type sensors. Flexible sensors may simply comprise an adhesive strip onto which the emitter(s)/detector are mounted for placement about a patient appendage. Clip-type sensors typically include two hingedly connected housings onto which the emitter(s) and detector are mounted. Generally, clip-type sensors are releasably attached to a patient's appendage (e.g., finger, ear lobe or the nasal septum) so that the appendage is isolated between the two housings.
Both mentioned sensor types present advantages and disadvantages. In particular, clip-type sensors may be advantageously reused on different patients and are relatively easy to attach to and remove from a patient tissue site. Further, the present inventor has recognized the desirability of providing a reusable sensor which securely attaches to a patient's appendage while reducing any interference with blood circulation, which is resistant to contamination, which yields reduced relative appendage movement, which is durable and which is configured for ease of assembly.
SUMMARY OF THE INVENTION
In view of the foregoing, a primary object of the present invention is to provide a reusable oximeter sensor which securely and reliably attaches to a patient's appendage while reducing any arterial blood flow interference.
Another objective of the present invention is to provide a reusable oximeter sensor that inhibits contaminant infiltration.
A further object of the present invention is to provide a reusable oximeter sensor which reduces relative movement of an inserted appendage.
An additional object of the present invention is to provide a reusable oximeter sensor having enhanced durability.
Yet another objective of the present invention is to provide a reusable pulse oximetry sensor which is relatively easy to assemble.
One or more of the above objectives and additional advantages are realized by the present invention. In one aspect, a clip-type pulse oximetry sensor is provided which comprises top and bottom members disposed in opposing and hinged relation, and a spring member interposed therebetween. More particularly, a resilient spring member may be located between the sensor's top and bottom members near a rearward end of the members (e.g., an end opposite to that which securably receives a patient appendage). The resilient spring member acts to provide the force required to close and thereby hold the forward ends of the top and bottom members on a patient's inserted appendage. Of note, the closing force may be provided by a combination of tensile and compressive portions integrated into the spring member. That is, when the sensor is secured upon a patient appendage a portion of the resilient hinge member is actuated to be tensioned and another portion is actuated to be compressed. Attempting to return to their non-deformed static condition, the tensile and compressive portions combinatively exert an enhanced closing force to reliably hold the sensor to the inserted appendage.
Preferably, contact surfaces of the spring member directly engage both the top and bottom members when the sensor is assembled, thereby facilitating force transfer therebetween. The contact surfaces may comprise wings which extend rearwardly at the top and bottom of the spring member. Relatedly, rearward ends of the top and bottom members may be rimmed and/or otherwise configured to provide conformal seats for flushly receiving the spring member wings. When compressive forces are applied to the rearward ends of the top and bottom members (e.g., via hand manipulation) the spring member wings are forced towards one another, compressing a rearward-facing portion of the spring member while tensioning a forward-facing portion of the spring member. Correspondingly, the forward ends of the top and bottom members will open to accommodate patient appendage insertion/positioning therebetween. When the compressive forces are released, the tensile and compressive portions of the spring member co-act to provide the above-noted closing force.
A rearward-facing side of the spring member (e.g., extending between the above-noted wings) is preferably defined by a continuous surface. For example, in a winged embodiment having a U-shaped profile, the rearward side of the spring member may comprise a concave, semi-cylindrical surface that extends between the top and bottom members across the width of the sensor to completely close the rear-end of the sensor. As may be appreciated, the provision of a continuous rearward surface on the spring member reduces contaminate infiltration into the sensor.
Of note, the spring member may be advantageously defined as a one-piece unit. More particularly, the resilient spring member may have an integral, monolithic structure. To provide such a structure, the spring member may advantageously comprise a molded polymeric material.
In the latter regard, and more generally, the resilient spring member preferably comprises an elastomeric material. By way of example only, the spring member may a material selected from a group consisting of thermoplastic elastomers, liquid silicone rubbers, polyolefin elastomers, thermoplastic rubbers urethanes and natural rubbers. The utilization of an elastomeric spring member facilitates the realization of a range of spring constants for different applications of the inventive sensor. As such, the same basic design/componentry of the inventive sensor may be employed for a number of different patient applications entailing different desired clamping forces for patient appendage securement. That is, only the specific elastomer utilized in the spring members needs to vary from sensor to sensor. For example, a large-finger patient sensor may comprise a spring member having a different modulus of elasticity than that of another spring member utilized in a small finger patient sensor.
Preferably, the spring member may comprise one or more openings to accommodate hinged interconnection of the top and bottom members and/or to allow for the routing of electrical wiring between the top and bottom members. More particularly, the spring member may comprise an opening extending laterally therethrough from side to side to accommodate a hinge pin that hingedly interconnects the top and bottom members. In this embodiment, the hinge pin acts as a fulcrum or hinge axis for the top and bottom members. Additionally, the hinge pin functionally separates the above-noted tensile and compressive portions of the hinge member. For example, when the sensor is opened (e.g. to accommodate insertion or after insertion of a patient appendage), the portion of the spring membe
Datex-Ohmeda Inc.
Kremer Matthew
Marsh & Fischmann & Breyfogle LLP
Winakur Eric F.
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