Patent Application
20210393207
The present disclosure relates generally to medical devices, and more particularly, to medical devices that monitor physiological parameters of a patient, such as pulse oximeters.
In the field of medicine, doctors often desire to monitor certain physiological characteristics of their patients. Accordingly, a wide variety of devices have been developed for monitoring many such physiological characteristics. Such devices provide doctors and other healthcare personnel with the information they need to provide the best possible healthcare for their patients. As a result, such monitoring devices have become an indispensable part of modern medicine.
One technique for monitoring certain physiological characteristics of a patient uses attenuation of light to determine physiological characteristics of a patient. This is used in pulse oximetry, and the devices built based upon pulse oximetry techniques. Light attenuation is also used for regional or cerebral oximetry. Oximetry may be used to measure various blood characteristics, such as the oxygen saturation of hemoglobin in blood or tissue, the volume of individual blood pulsations supplying the tissue, and/or the rate of blood pulsations corresponding to each heartbeat of a patient. The signals can lead to further physiological measurements, such as respiration rate, glucose levels or blood pressure.
One issue in such sensors relates to the bandage of the sensor involves removal of the bandage and re-application. One example of this involves monitoring of a patient for blood oxygenation (e.g., SpO2 or rSO2), wherein the sensor (with particular emphasis on, for example, the disposable part of the sensor that adheres to the patient) must be removed to check the skin integrity. This can occur multiple times over a time span of a single sensor use, which can be up to 24 hours, 72 hours, or more. Accordingly, the sensor must be removed and re-adhered with minimal disruption to the patient, while still retaining sensor adherence to the skin.
Traditional pulse oximeter sensor designs utilize patient side adhesives such as acrylic or synthetic rubber adhesives. A common complaint with such sensors includes discomfort due to removal that is a frequent hospital procedure, or apparent discomfort expressed, for example by infants in Neonatal Intensive Care Units (NICUs). Another common complaint relates to loss of peel strength after the sensor removal, affecting its ability to be reapplied.
Minimal disruption to the skin is especially for patients with fragile skin, such as neonates. Disruption to the skin can occur over time as the sensor is removed multiple times or during the first removal. These disruptions can be as severe as skin tearing or just causing discomfort on removal. In neonates, for example, any added stress, such as disruption due to an adhesive bandage removal, can cause unwanted desaturation events (where the blood oxygen levels decrease) and are avoided when possible.
Accordingly, there is a need in the art for more robust medical sensors that would provide more widespread acceptance in common usage, which requires removal and re-adherence of the sensor.
The techniques of this disclosure generally relate to medical devices that monitor physiological parameters of a patient, such as pulse oximeters.
In one aspect, the present disclosure provides a patient monitoring sensor having a communication interface, through which the patient monitoring sensor can communicate with a monitor. The patient monitoring sensor also includes a light-emitting diode (LED) communicatively coupled to the communication interface and a detector, communicatively coupled to the communication interface, capable of detecting light. The patient monitoring sensor further includes a patient-side adhesive with repeatable removal and re-adherence characteristics, preventing disruption to a patient while at the same time retaining sensor adherence to the skin, the patient-side adhesive comprising a silicone adhesive.
In another aspect, the disclosure provides a patient monitoring sensor having a communication interface, through which the patient monitoring sensor can communicate with a monitor, wherein the sensor also includes a silicone patient-side adhesive that provides a peel force attachment, including after repositioning, for example in a range from about 0.5 to 0.8 N/cm from skin. In exemplary embodiments, the adhesive retains 80% of the initial peel force from skin after the 18th removal.
In further exemplary embodiments such patient-side adhesive does not disrupt the skin (e.g., by removing only minimal skin protein) during removal, for example in a range from about 0.2 to 0.3 N/cm from skin. In exemplary embodiments, adhesives in accordance with the present disclosure such minimal protein removal is at or below 1.5 micrograms per centimeter squared (μg/cm{circumflex over ( )}2). In other exemplary embodiments protein removal is at or below 5 μg/cm{circumflex over ( )}2, at or below 4 μg/cm{circumflex over ( )}2, at or below 3 μg/cm{circumflex over ( )}2, at or below 2 μg/cm{circumflex over ( )}2 or at or below 1 μg/cm{circumflex over ( )}2.
Further, such exemplary silicone patient-side adhesives do not increase water loss through the skin (as measured via trans-epidermal water loss, per the below over a two hour period), for example by providing <1 mg/cm{circumflex over ( )}2*hr increase from use. In other exemplary embodiments, adhesives in accordance with the present disclosure provide an increase of about 0.6 g/m{circumflex over ( )}2 h from baseline (the initial measurement before the sensor is placed on the skin) for transepidermal water loss (TEWL).
In exemplary embodiments, a suitable adhesive includes silicone gel or silicone pressure sensitive adhesives with thickness between about 0.1 mm to 1.5 mm.
In another aspect, the disclosure provides a patient monitoring system, having a patient monitor coupled to a patient monitoring sensor. The patient monitoring sensor includes a communication interface, through which the patient monitoring sensor can communicate with the patient monitor. The patient monitoring sensor also includes a light-emitting diode (LED) communicatively coupled to the communication interface and a detector, communicatively coupled to the communication interface, capable of detecting light. The patient monitoring sensor further includes a silicone patient-side adhesive.
The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.
As has been noted above, traditional pulse oximeter sensor designs utilize patient side adhesives such as acrylic or synthetic rubber adhesives. A common complaint with such sensors includes discomfort due to removal that is a frequent hospital procedure, or apparent discomfort expressed, for example by infants in Neonatal Intensive Care Units (NICUs). Another common complaint relates to loss of peel strength after the sensor removal, affecting its ability to be reapplied.
The present disclosure recognizes that better adhesives for these applications may be identified, not only for comfort (gentleness), but also for the well-being of patients in situations where bandages with adhesives must not only be worn, but must also be removed and reapplied. Further, consideration of adhesives must also account for a variety of factors, including without limitation: sweat from patients; humidity of environments; contaminants on the patient-side of a sensor prior to placement; amount(s) of dead skin sloughing; smoothness (morphology) of epidermis; dwell time; variability in initial force provided by a clinician; part-to-part variation of the bandage footprint; material stability; use case duration; and reapplication time interval(s). Additional factors include possible skin integrity or residue problems upon removal.
Accordingly, the present disclosure describes a patient monitoring sensor that includes silicone patient-side adhesives provided as a part of the patient bandage, exemplary embodiments, the silicone patient-side adhesive provides a peel force attachment, including after repositioning, for example in a range from about 0.5 to 0.8 N/cm from skin. In exemplary embodiments, the adhesive retains at least 80% of the initial peel force from skin after the 18th removal. In further exemplary embodiments, the adhesive retains at least 60% of the initial peel force from the skin after the 18th removal. In further exemplary embodiments, the adhesive retains at least 40% of the initial peel force from the skin after the 18th removal. In exemplary embodiments, peel force is measured according to the ASTM D3330 standard.
In further exemplary embodiments such patient-side adhesive does not disrupt the skin (e.g., by removing only minimal skin protein) during removal, for example in a range from about 0.2 to 0.3 N/cm from skin. In exemplary embodiments, adhesives in accordance with the present disclosure such minimal protein removal is at or below 1.5 micrograms per centimeter squared (μm/cm{circumflex over ( )}2). In other exemplary embodiments protein removal is at or below 5 μg/cm{circumflex over ( )}2, at or below 4 μg/cm{circumflex over ( )}2, at or below 3 μg/cm{circumflex over ( )}2, at or below 2 μg/cm{circumflex over ( )}2 or at or below 1 μg/cm{circumflex over ( )}2.
Further, such exemplary silicone patient-side adhesives do not increase water loss through the skin (as measured via trans-epidermal water loss), for example by providing <1 mg/cm{circumflex over ( )}2*hr increase from use. In other exemplary embodiments, adhesives in accordance with the present disclosure provide an increase of about 0.6 g/m{circumflex over ( )}2 h from baseline (the initial measurement before the sensor is placed on the skin) for transepidermal water loss (TEWL).
In exemplary embodiments, a suitable adhesive includes silicone gel or silicone pressure sensitive adhesives with thickness between about 0.1 mm to 1.5 mm.
In another aspect, the disclosure provides a patient monitoring sensor having a communication interface, through which the patient monitoring sensor can communicate with a monitor, wherein the sensor also includes a patient-side silicone adhesive providing comfort, including during re-application, with minimal damage to the skin, as measured by the change to the initial rate of water loss through the skin.
In another aspect, the disclosure provides a patient monitoring system, having a patient monitor coupled to a patient monitoring sensor. The patient monitoring sensor includes a communication interface, through which the patient monitoring sensor can communicate with the patient monitor. The patient monitoring sensor also includes a light-emitting diode (LED) communicatively coupled to the communication interface and a detector capable of detecting light. The patient monitoring sensor includes a patient-side silicone adhesive providing comfort, including during re-application, with minimal damage to the skin, as may be measured by the change to the initial rate of water loss through the skin.
Referring now to
In the embodiment of
The sensor 14 also includes a sensor body 46 to house or carry the components of the sensor 14. The body 46 includes a backing, or liner, provided around the emitter 16 and the detector 18, as well as an adhesive layer (not shown in
In the embodiment shown, the sensor 14 is communicatively coupled to the patient monitor 12. In certain embodiments, the sensor 14 may include a wireless module configured to establish a wireless communication 15 with the patient monitor 12 using any suitable wireless standard. For example, the sensor 14 may include a transceiver that enables wireless signals to be transmitted to and received from an external device (e.g., the patient monitor 12, a charging device, etc.). The transceiver may establish wireless communication 15 with a transceiver of the patient monitor 12 using any suitable protocol. For example, the transceiver may be configured to transmit signals using one or more of the ZigBee standard, 802.15.4x standards WirelessHART standard, Bluetooth standard, IEEE 802.11x standards, or MiWi standard. Additionally, the transceiver may transmit a raw digitized detector signal, a processed digitized detector signal, and/or a calculated physiological parameter, as well as any data that may be stored in the sensor, such as data relating to wavelengths of the emitters 16, or data relating to input specification for the emitters 16, as discussed below. Additionally, or alternatively, the emitters 16 and detectors 18 of the sensor 14 may be coupled to the patient monitor 12 via a cable 24 through a plug 26 (e.g., a connector having one or more conductors) coupled to a sensor port 29 of the monitor. In certain embodiments, the sensor 14 is configured to operate in both a wireless mode and a wired mode. Accordingly, in certain embodiments, the cable 24 is removably attached to the sensor 14 such that the sensor 14 can be detached from the cable to increase the patient's range of motion while wearing the sensor 14.
The patient monitor 12 is configured to calculate physiological parameters of the patient relating to the physiological signal received from the sensor 14. For example, the patient monitor 12 may include a processor configured to calculate the patient's arterial blood oxygen saturation, tissue oxygen saturation, pulse rate, respiration rate, blood pressure, blood pressure characteristic measure, autoregulation status, brain activity, and/or any other suitable physiological characteristics. Additionally, the patient monitor 12 may include a monitor display 30 configured to display information regarding the physiological parameters, information about the system (e.g., instructions for disinfecting and/or charging the sensor 14), and/or alarm indications. The patient monitor 12 may include various input components 32, such as knobs, switches, keys and keypads, buttons, etc., to provide for operation and configuration of the patient monitor 12. The patient monitor 12 may also display information related to alarms, monitor settings, and/or signal quality via one or more indicator lights and/or one or more speakers or audible indicators. The patient monitor 12 may also include an upgrade slot 28, in which additional modules can be inserted so that the patient monitor 12 can measure and display additional physiological parameters.
Because the sensor 14 may be configured to operate in a wireless mode and, in certain embodiments, may not receive power from the patient monitor 12 while operating in the wireless mode, the sensor 14 may include a battery to provide power to the components of the sensor 14 (e.g., the emitter 16 and the detector 18). In certain embodiments, the battery may be a rechargeable battery such as, for example, a lithium ion, lithium polymer, nickel-metal hydride, or nickel-cadmium battery. However, any suitable power source may be utilized, such as, one or more capacitors and/or an energy harvesting power supply (e.g., a motion generated energy harvesting device, thermoelectric generated energy harvesting device, or similar devices).
As noted above, in an embodiment, the patient monitor 12 is a pulse oximetry monitor and the sensor 14 is a pulse oximetry sensor. The sensor 14 may be placed at a site on a patient with pulsatile arterial flow, typically a fingertip, toe, forehead or earlobe, or in the case of a neonate, across a foot. Additional suitable sensor locations include, without limitation, the neck to monitor carotid artery pulsatile flow, the wrist to monitor radial artery pulsatile flow, the inside of a patient's thigh to monitor femoral artery pulsatile flow, the ankle to monitor tibial artery pulsatile flow, and around or in front of the ear. The patient monitoring system 10 may include sensors 14 at multiple locations. The emitter 16 emits light which passes through the blood perfused tissue, and the detector 18 photoelectrically senses the amount of light reflected or transmitted by the tissue. The patient monitoring system 10 measures the intensity of light that is received at the detector 18 as a function of time.
A signal representing light intensity versus time or a mathematical manipulation of this signal (e.g., a scaled version thereof, a log taken thereof, a scaled version of a log taken thereof, etc.) may be referred to as the photoplethysmograph (PPG) signal. In addition, the term “PPG signal,” as used herein, may also refer to an absorption signal (i.e., representing the amount of light absorbed by the tissue) or any suitable mathematical manipulation thereof. The amount of light detected or absorbed may then be used to calculate any of a number of physiological parameters, including oxygen saturation (the saturation of oxygen in pulsatile blood, SpO2), an amount of a blood constituent (e.g., oxyhemoglobin), as well as a physiological rate (e.g., pulse rate or respiration rate) and when each individual pulse or breath occurs. For SpO2, red and infrared (IR) wavelengths may be used because it has been observed that highly oxygenated blood will absorb relatively less Red light and more IR light than blood with a lower oxygen saturation. By comparing the intensities of two wavelengths at different points in the pulse cycle, it is possible to estimate the blood oxygen saturation of hemoglobin in arterial blood, such as from empirical data that may be indexed by values of a ratio, a lookup table, and/or from curve fitting and/or other interpolative techniques.
Referring now to
While any number of exemplary sensor designs are contemplated herein, in the illustrated exemplary embodiment, the body 100 includes a flap portion 116 that includes an aperture 108. The flap portion 116 is configured to be folded at a hinge portion 114 such that the aperture 108 overlaps the detector 106. In one embodiment, the flap portion 116 includes an adhesive 110 that is used to secure the flap portion 116 to the body 102 after the flap portion 116 is folded at the hinge portion 114.
The sensor 100 includes a plug 120 that is configured to be connected to a patient monitoring system, such as the one shown in
In exemplary embodiments, the aperture 108 is configured to provide electrical shielding to the detector 106. In exemplary embodiments, aperture 108 also limits the amount of light that is received by the detector 106 to prevent saturation of the detector. In exemplary embodiments, the configuration of the aperture 108, i.e., a number, shape, and size of the openings that define the aperture 108 can vary. As illustrated, in one embodiment, the aperture 108 includes a single round opening. In other embodiments, the aperture 108 can include one or more openings that have various shapes and sizes. The configuration of the aperture 108 is selected to provide electrical shielding for the detector 106 and/or control the amount of light that is received by the detector 106. In exemplary embodiments, the body 102 includes a visual indicator 112 that is used to assure proper alignment of the flap portion 116 when folded at the hinge portion 114.
Referring now to
As we have noted, regardless of sensor configuration particulars of the above-described exemplary embodiments, the sensor includes a silicone patient-side adhesive. Exemplary benefits of such a silicone patient-side adhesive include a peel force attachment, including after repositioning, minimization of disruption of and damage to the skin (e.g., by removing only minimal skin protein) during removal and comfort, among others.
Further, in embodiments where at least a portion of the materials used in the construction of the sensor comprise hydrophobic materials, for example including a polyester backing, such silicone patient-side adhesives contribute to hydrophobic qualities of the bandage, preventing adverse odor and a reduction of bacteria over time of use. Accordingly, such a sensor, including the silicone patient-side adhesive, will absorb less moisture from the environment, for example from a humid environment or from handwashing, etc. This provides a sensor with more longevity of use and more pleasing effects, and further results in reduction of total cost per patient by extending the useful life of the sensor.
Exemplary materials for backing material includes plastics, such as polypropylene (PP), polyester (PES), polyethylene (PE), urethanes, silicone, or the like. Additionally, various layers of the device may be constructed of one or more hydrophobic materials.
Exemplary materials for patient adhesive include gentle removal adhesives, such as various silicone adhesives that provide resilience (for re-adhesion) after repositioning, comfort, lack of water loss through patient skin (as measured via trans-epidermal water loss), which lack of water loss correlates with gentle release of the adhesive, etc.
One or more specific embodiments of the present techniques will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made, which may vary from one implementation to another.
It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device.
