The following relates generally to the phototherapy arts, infant safety monitoring arts, jaundice treatment arts, patient monitoring arts, and related arts.
Bilirubin is a yellow pigment in blood and stool resulting from the breakdown of red cells. In the liver, bilirubin is excreted into the bile duct and stored in gallbladder. Eventually, bilirubin is released into the small intestine as bile to help digest fats and ultimately excreted with the stool. Hyperbilirubinemia refers to too much bilirubin in the blood and also results in yellowing of skin, eyes and other tissues leading to conditions such as jaundice. About 60% of term newborns and 80% of premature babies develop hyperbilirubinemia which may lead to jaundice. Newborn infants often have mild jaundice due to normal changes in the metabolism of bilirubin. These changes can be first signs of a medical problem. Jaundice in a newborn can be very serious and life threatening if left untreated. Bilirubin in the infant's blood may be tested several times in the first few days to check liver functioning, which is an invasive method.
Phototherapy is the most common treatment for reducing high bilirubin levels that cause jaundice in a newborn. A baby with jaundice may need to stay under a phototherapy light for several days. Potential problems that may occur during phototherapy include skin rash, damage to the nerve layer at the back of the eye (e.g., retina), dehydration, and separation from the infant's mother. Doctors check bilirubin levels at certain interval of time. Traditional bilirubin level screening has a number of limitations such as blood is collected for testing via venepuncture, which causes the baby pain and adds additional infection risks.
Currently, there exists non-invasive devices to check bilirubin levels in infant. A ColorMate III device (available from Chromatics Color Sciences, Intl, Inc.; Rockville, Md., USA) checks infant bilirubin levels based on color of skin and estimates bilirubin from skin reflectance. This device uses a Xenon flash tube and light sensors to measure wavelengths from 400 nm to 700 nm; and requires a baseline Total Serum Bilirubin (TSB) reading on each newborn baby. A Minolta/Air Shields JM-103 device (available from Konica Minolta Sensing Americas, Inc. Ramsey, N.J., USA) determines the bilirubin from the subcutaneous tissue of neonate; and determines difference in the optical differences of reflected light at 450 nm and 550 nm by infant skin. A Philips® Bilicheck (available from Koninklijke Philips N.V., Eindhoven, the Netherlands) measures bilirubin transcutaneously by using the visible light (380-760 nm) reflected by skin and subtracts light absorption of interfering factors such as hemoglobin and melanin to obtain bilirubin concentration. This device includes a disposable tip for each measurement. A Bilicam device (University of Washington, Seattle, Wash., USA) is a smartphone based medical device that uses the embedded cellphone camera and a paper based color calibration card to estimate jaundice from which the bilirubin level is inferred. The approach uses color balance in obtained images, obtains intensities of various reflected wavelengths and chromatic and achromatic properties from the skin, and estimates a bilirubin level using machine learning techniques. A CoSense® End-Tidal Carbon Monoxide (ETCO) Monitor (available from Capnia, Inc. Redwood City, Calif., USA) automates non-invasive detection of analytes in exhaled breath. This device acquires a breath sample with a tube inserted into a nostril for about thirty seconds, and displays the results in three to four minutes.
The following discloses new and improved systems and methods to address these problems.
In one disclosed aspect, a phototherapy monitoring device includes a housing configured for attachment to a patient, and a user interfacing device. An optical bilirubin sensor includes one or more light sources operative to generate probe light and arranged on or in the housing such that the probe light is reflected from or transmitted through skin of the patient when the housing is attached to the patient; and one or more photodetectors arranged on or in the housing to detect the probe light reflected from or transmitted through the skin of the patient. At least one electronic processor is disposed on or in the housing and programmed to: continuously generate a current bilirubin level measurement from the detected probe light reflected from or transmitted through the skin of the patient; and control the user interfacing device to generate a notification when the current bilirubin level measurement satisfies a safe bilirubin level.
In another disclosed aspect, a phototherapy monitoring device includes a housing configured for attachment to a patient At least two illuminators are secured to the housing and arranged to emit light towards at least a portion of the patient. A first illuminator is configured to emit light at a first wavelength and a second illuminator being configured to emit light at a second, different wavelength. A photodetector is configured to measure intensities of light reflected from the patient at the first and second wavelengths. At least one electronic processor programmed to: continuously estimate a bilirubin level in the patient by comparing the measured intensity of light at the first and second wavelengths; and generate an indication of whether the continuously estimated bilirubin level in the patient has decreased to a safe level.
In another disclosed aspect, a method of monitoring phototherapy delivered to a patient includes: with at least two illuminators secured to a housing attached to the patient, emitting light towards at least a portion of the patient at a first wavelength and a second, different wavelength; with at least two photodetectors, measuring intensities of light reflected from the patient at the first and second wavelengths; and with at least one electronic processor: continuously estimate a bilirubin level in the patient by comparing the measured intensity of light at the first and second wavelengths; apply a linear model to the continuously estimated bilirubin level in the patient to determine a remaining amount of time for phototherapy, the model further receiving as inputs at least patient age, patient skin color, and the safe level; and generate an indication of whether the continuously estimated bilirubin level in the patient has decreased to a safe level based on the continuously estimated bilirubin level.
One advantage resides in continuous monitoring of bilirubin levels in neonates during phototherapy.
Another advantage resides in providing immediate notification when a continuously measured level of bilirubin reaches a safe level.
Another advantage resides in reduction of skin irritation, dehydration, retina damage, and hypocalcaemia in neonates undergoing phototherapy by way of rapidly determining when the phototherapy has achieved the clinical goal, and/or by estimating when the phototherapy will achieve the clinical goal.
Another advantage resides in reduction of separation time between the neonate and the mother by enabling termination of the phototherapy as soon as the clinical bilirubin level goal is achieved.
Another advantage resides in sending automatic notifications when a measured level of bilirubin reaches a safe level.
Another advantage resides in determining a correct exposure time of the neonate to phototherapy.
Another advantage resides in determining a remaining time for a neonate to undergo phototherapy.
A given embodiment may provide none, one, two, more, or all of the foregoing advantages, and/or may provide other advantages as will become apparent to one of ordinary skill in the art upon reading and understanding the present disclosure.
The disclosure may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the disclosure.
Hyperbilirubinemia is a condition in which the blood contains too much bilirubin. Jaundice is a chief symptom of hyperbilirubinemia, and the condition is common in newborn infants due to delayed development of bilirubin removal functionality of the liver. Phototherapy is a common treatment for hyperbilirubinemia, but the therapy has various adverse side effects and hence is preferably applied only for a sufficient time to reduce the bilirubin to safe levels. Conventionally, periodic blood tests or a handheld bilirubin meter is used to monitor the bilirubin level intermittently.
The following discloses an automated bilirubin meter that straps to the infant, e.g. to the forehead or belly, and provide continuous measurement of bilirubin level. The bilirubin meter is sized to minimally cover a portion of the infant, and does not affect phototherapy light from reaching the infant. Phototherapy light reflected by the infant's skin has a low intensity and is sensitive to ambient light. Hence, a case or housing of the device is made from an opaque material. The opaque structure of the device prevents ambient light interference in the interaction of blue and green light emitted from LEDs of the device with the infant's skin.
Continuous bilirubin measurement provides enhanced capabilities over a conventional handheld bilirubin meter. The bilirubin level can be tracked over time, and the bilirubin level versus time curve can be analyzed to estimate when the phototherapy will reduce the bilirubin to a safe level. In embodiments disclosed herein, a suitable model is a linear model parameterized by infant age, skin color (i.e. dark or light, not the jaundice-induced yellowing), initial (or current) bilirubin level, and the target bilirubin level (e.g., prescribed by a physician). More complex models, e.g. a quadratic or exponential model, are also contemplated. In existing phototherapy devices the intensity of the therapeutic blue light is fixed; however, if this intensity is an adjustable parameter then the physician might elect to increase the therapeutic blue light intensity if the estimated time-to-safe-level is deemed to be too long.
The continuous bilirubin measurement is also contemplated to provide for automated control. In one approach, the phototherapy device may be turned off when the bilirubin reaches a safe (e.g. physician-prescribed) level. To avoid premature termination of the phototherapy due to measurement noise, this may be done only after the safe level is maintained for some time interval. If the therapeutic blue light intensity is adjustable then in a more advanced embodiment the therapeutic blue light intensity may be controlled, e.g. using the linear model prediction to achieve a target time to safe level.
The continuous bilirubin measurement is preferably coupled with automatic notifications, e.g. to notify medical personnel when the bilirubin has reached the safe (e.g. physician-prescribed) level. Other embodiments disclosed herein include providing an optical detector with a bandpass filter to measure the therapeutic blue light intensity, and to provide an alert if the phototherapy device is not delivering the blue light at a therapeutically effective (or physician-prescribed) intensity level.
With reference to
During the phototherapy, the level of bilirubin in the blood is continuously monitored by an illustrative phototherapy monitoring device 10. In particular, the illustrative phototherapy monitoring device 10 is configured for used with the neonate 6, but more generally may be used for any patient (infant or adult) afflicted with hyperbilirubinemia and/or exhibiting jaundice. With reference to
With continuing references to
The bilirubin sensor 14 also includes one or more photodetectors or receivers 18 configured to measure probe light reflected from the patient. As shown in
The light sources 16 and the photodetectors 18 are arranged on the bottom face 15 of the housing 12 (The device 10 shown in
As shown in
The device 10 further includes a control circuit that is operatively connected to the illuminators 16 and the receivers 18, and disposed on or in the housing 12. The control circuit may, for example, comprise at least one electronic processor 28, a microprocessor or microcontroller and ancillary electronic components such as a memory chip (e.g. EPROM, EEPROM, flash memory, et cetera), discrete components (e.g. resistors, capacitors), and/or so forth, with (for example) the memory chip storing executable code (e.g. software or firmware) executable by the microprocessor or microcontroller to perform processing functions as described herein. Optionally, the control circuit may additionally or alternatively include analog processing circuitry, e.g. an operational amplifier (op-amp) circuit designed to compare inputs including a reflected light intensity measurement reading from the photodetectors 18 and a reference signal corresponding to the maximum permissible intensity measurement and to generate a control signal based on the comparison.
In some embodiments, the processor 28 is programmed to continuously generate or estimate a current bilirubin level measurement in the patient from the detected probe light reflected from or transmitted through the skin of the patient. To do so, the the processor 28 is programmed to continuously compare the measured intensity of light at the first and second wavelengths detected by the photodetectors 18. This operation can performed using known methods (see, e.g., Penhaker et al., “Advanced Bilirubin Measurement by a Photometric Method,” ELEKTRONIKA IT ELECTROTECHNIKA, ISSN 1392-1215, Vol. 19, No. 3, 2013). In one example, the electronic processor 28 is programmed to continuously generate the current bilirubin level measurement from the intensities of the detected first and second probe light reflected from the skin of the patient. In another example, the electronic processor 28 is programmed to continuously generate the current bilirubin level measurement from skin color data derived from the detected spectrum of the polychromatic probe light reflected from the skin of the patient.
In other embodiments, accuracy of skin-based bilirubin measurement are lower than a blood-based measurement due to the presence of skin pigmentations, such as melamine. In some embodiments, the electronic processor 28 is programmed to calibrate the photodetectors 18 with bilirubin levels obtained from blood of the patient (this is typically done at least once a day immediately after birth in the hospital). These bilirubin levels are entered in the device 10. After one or more such values are entered, the device 10 can compensates for the infant's individual skin pigmentation and read bilirubin accurately.
In some embodiments, the processor 28 is programmed to apply a model 44 (see
The processor 28 is also programmed to control the user interfacing device to generate a notification or indication when the current bilirubin level measurement satisfies a safe bilirubin level, such as when the continuously estimated bilirubin level in the patient has decreased to a safe level. In some embodiments, the processor 28 is programmed to control the display screen 20 to output display a textual or visual message of the indication that the current bilirubin level measurement satisfies a safe bilirubin level. The display screen 20 can also be controlled to output or display the continuously estimated current bilirubin level as, for example, a real-time value and/or a trend line. In another example, the processor 28 is programmed to control the loudspeaker 22 to sound an audible alarm when the current bilirubin level measurement satisfies the safe bilirubin level. In another example, the processor 28 is programmed to control the wireless communication interface 24 to transmit the notification as an electronic message to the medical professional. In another example, the processor 28 is programmed to control the alert light 26 to illuminate to output the generated indication when the current bilirubin level measurement satisfies a safe bilirubin level.
Referring back to
In the foregoing examples, the determination of when the bilirubin level reaches the safe level may be done in such a way so as to limit the effects of measurement noise. For example, the safe level may be determined to have been reached only when the continuously measured bilirubin level remains at or below the safe level for some pre-set time interval, e.g. for at least one hour. It is also noted that “continuous” measurement of the bilirubin level encompasses digital sampling at reasonably fast sampling rates, e.g. a digital bilirubin measurement value may updated every second, or every minute, or every two minutes, or so forth. By “continuous”, it is meant that the bilirubin measurements are acquired sequentially in an automated fashion, as opposed to, for example, a manual bilirubin meter that would need to be positioned manually and triggered to acquire a bilirubin measurement.
Referring back to
With reference to
In some embodiments, if the phototherapy device 8 provides for adjustment of the intensity level of the therapeutic light then this intensity may be adjusted based on the predicted time to safe bilirubin level. For example, if that time is deemed to be too long then the therapeutic light intensity may be increased to expedite the phototherapy. In these embodiments, the therapeutic blue light intensity should be another input for training of the model 44, and the therapeutic blue light intensity is also an input during the inference phase. In embodiments in which the phototherapy device 8 is controlled by the phototherapy monitoring device 10, it is also contemplated to automatically control the therapeutic blue light intensity based on the estimated time-to-safe bilirubin level. For example, the therapeutic blue light may be set to the lower of (1) the minimum therapeutic blue light intensity for achieving safe bilirubin level by a pre-set time interval or (2) a pre-set absolute maximum allowable therapeutic blue light intensity.
With reference to
The disclosure has been described with reference to the preferred embodiments. Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the disclosure be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Filing Document | Filing Date | Country | Kind |
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PCT/EP2019/060414 | 4/24/2019 | WO | 00 |
Number | Date | Country | |
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62663331 | Apr 2018 | US |