Optical vital sign detection method and measurement device

“VITAL SIGNAL MEASUREMENT DEVICE” CROSS REFERENCE TO RELATED REQUESTS

This application claims the benefit of, and priority for, provisional patent application US 60 / 802,810, filed on May 24, 2006, provisional patent application US 60 / 874,665, filed on December 13, 2006, and patent application US 60 / 898,269, deposited on January 31, 2007, all of which are incorporated herein in their entirety, by reference.

TECHNICAL FIELD

This invention relates to the detection of vital signs and, more particularly, to a device for measuring vital signs.

FUNDAMENTALS

Blood pressure refers to the force exerted by the blood circulating on the walls of blood vessels and is one of the main vital signs. Systolic pressure is the peak pressure in the arteries, which occurs near the beginning of the cardiac cycle. Diastolic pressure is the lowest pressure that occurs in the resting phase of the cardiac cycle. Mean pressure throughout the cardiac cycle is reported as mean blood pressure. The pressure pulse reflects the difference between the maximum and minimum measured pressures.

Blood pressures can be measured invasively (penetrating the skin and measuring themselves inside blood vessels) or non-invasively. The first is usually limited to a hospital environment. Non-invasive auscultation and oscillometric methods are simpler and faster than invasive methods, have less complications, and are less unpleasant and less painful for the patient. Non-invasive measurement methods are most commonly used for routine examinations and monitoring.

The auscultation method typically uses a stethoscope and a sphygmanometer. An inflatable air balloon is placed around the upper arm, at approximately the same vertical height as the heart, and is connected pneumatically to a mercury manometer or an aneroid meter. The mercury manometer measures the height of a mercury column, giving a measurement of the absolute pressure of the pneumatic balloon without the need for calibration and, consequently, not being subject to calibration errors and deviations that affect other pressure meters. The pneumatic balloon is manually inflated by repeatedly squeezing a rubber bulb until the brachial artery is closed completely. When listening with the stethoscope over the brachial artery, away from the pressurized pneumatic balloon, the examiner slowly releases the pressure in the pneumatic balloon. As soon as the blood begins to flow in the artery, the turbulent flow creates a hissing or hammering sound (first Korotkoff sounds). The pressure at which this sound is first heard is systolic blood pressure. The pressure of the pneumatic balloon is released even more until no sound can be heard (fifth Korotkoff sound), in diastolic blood pressure.

Oscillometric methods are sometimes used for continuous monitoring and sometimes for making a single measurement. The equipment is functionally similar to that of the auscultation method, but it is not based on the use of a stethoscope and the ear of this place, the detection medium is a pressure sensor that is connected pneumatically to the pneumatic balloon and records the oscillations (relatively small ) in the pressure of the pneumatic balloon, which are synchronous in the shape of an examiner. Blood pressure wave. The first fluctuation in the pressure of the pneumatic balloon does not occur in the systolic pressure, but in a pressure of the pneumatic balloon substantially above the systolic pressure. The pneumatic balloon is initially inflated to a pressure above systolic blood pressure. The pressure of the pneumatic balloon is then gradually reduced. The values ​​of systolic and diastolic pressures are calculated from the different oscillations of amplitudes that occur at various pressures of the pneumatic balloon by using an algorithm. The algorithms used to calculate systolic and diastolic pressures often use coefficients obtained experimentally in order to match, as best as possible, oscillometric results with results obtained using the auscultation method.

SUMMARY

In some respects, a vital sign measurement device includes a sensor clamping device, an optical sensing system, and an output unit. The sensor fixation device is adapted to be placed against an anatomical location of an individual, within which is an artery. The optical sensing system includes an optical source, an optical reffator, and an optical detector, all attached by the sensor fixture and moving with the movement of the sensor fixture. The optical sensing system is positioned in relation to the sensor fixation device to sense the movement corresponding to an arterial pulse when the sensor fixation device is placed against the individual's anatomical location. The optical sensing system can sense an arterial pulse from moving, folding, or compressing at least a portion of the optical sensing system in relation to other portions of the optical sensing system, which can result in a change in a signal optical received by the optical detector. The output unit receives an input indicating the movement corresponding to an arterial pulse from the optical sensing system and generates, using the input, a vital sign measurement.

In some implementations, the sensor clamping device may be an inflatable pneumatic balloon. In some implementations, the vital sign measurement device may include a pressure sensor to sense pressure applied to an anatomical location. In some implementations, the output unit can receive, from a pressure sensor, a pressure input indicative of the pressure applied to the anatomical position and generate a vital signal using the input from the optical sensing system and the pressure input .

In some implementations, the anatomical location on the individual's body can be an upper arm, and the sensor fixation device can be configured so that the optical sensing system is positionable to sense movement due to a pulsation of an artery brachial. In some implementations, the individual's anatomical location can be a wrist, and the sensor fixation device can be configured so that the optical sensing system is positionable to sense movement due to a pulsation of a radial artery. In some implementations, the individual's anatomical location can be an ankle, and the sensor fixation device can be configured so that the optical sensing system is positionable to sense movement due to a pulse in one or more arteries in the ankle.

In some implementations, the optical refractor can be a compressible and / or flexible waveguide. In some implementations, the optical refractor can be a diffuser.

In some implementations, the optical source and the optical refractor can be configured to produce a granularity pattern output. The optical detector can be positioned to detect a portion of the granularity pattern output and generate, from there, a signal indicative of the optical energy received within the detected portion of the granularity pattern output. In some implementations, the optical sensor may include a spatial optical occluder component that prevents the optical detector from receiving a portion of the granularity pattern output. In some implementations, the optical detector may have an optical energy receiving portion having a smaller surface area than the output of the granularity pattern. For example, the surface area of ​​the optical energy receiving portion can be 100 times smaller than the size of an average granule.

In some implementations, the optical source can be a coherent light source (for example, a laser).

In some implementations, the vital sign can be at least one of a heart rate, an arterial pulse waveform, a systolic blood pressure, a diastolic blood pressure, an average arterial blood pressure, a pulse pressure, and an arterial compliance .

In some implementations, the output unit can generate a vital signal measurement using a signal indicative of the optical signal received by the optical detector.

In some implementations, the vital sign measurement device may include a display to display a measurement of the vital sign generated by the output unit. In some implementations, the vital sign measurement device may include an alarm system to produce a human-detectable signal, when a vital sign measurement generated by the output unit meets predetermined criteria.

In some implementations, the vital sign measurement device may include a spring attached to at least a portion of the optical sensing system to counteract an arterial pulse force and return the optical sensing system to an initial state after the pulsation arterial.

In some implementations, the vital sign measurement device may include a pressure transmission device, adapted to be placed against a second anatomical location of an individual, close to the anatomical location of the sensor fixation device, to allow the detection of the pulse arterial by the optical sensing system in a distal and separate position from the pressure transmission device.

In some implementations, the optical sensing system and the output unit can be adapted to sense a pulse amplitude of arterial pulsation from moving, bending, or compressing at least a portion of the optical sensing system in relation to other portions of the optical sensing system, which can result in a change in the optical signal received by the optical detector. In some implementations, the optical sensing system can be configured to detect optical signals representative of a series of arterial pulsations and the output unit can be adapted to determine a pulse waveform for each of the series of arterial pulsations.

In some ways, a method of measuring an individual's vital sign includes placing a sensor clamping device against an individual's anatomical location, sensing the movement corresponding to an arterial pulse, and generating a vital sign measurement. The sensor clamping device attaches an optical sensing system comprising an optical source, an optical refractor and an optical detector, all attached by the sensor clamping device and moving with the movement of the sensor clamping device. An arterial pulse can result in the movement, bending, or compression of at least a portion of the optical sensing system in relation to other portions of the optical sensing system, which can result in a change in an optical signal received by the optical detector. The vital signal is generated using an input indicative of changes in the amount of optical energy received by the optical detector.

In some implementations, the method may include applying pressure to the individual's anatomical location with the sensor fixation device. For example, the method may include reducing the pressure applied to the anatomical location with the sensor clamping device over time and determining a series of pulse characteristics for arterial pulsations during the time from changes in the optical signal received by the optical detector over the time period. The vital sign measurement generated can be based on the series of pulse characteristics over the period of time.

In some implementations, the method may include obtaining a measured blood pressure measurement, a characteristic of the initial pulse, and a characteristic of the subsequent pulse and the generation of a vital sign based on the measured blood pressure measurement, the characteristic of the initial pulse, and the characteristic of the subsequent pulse. The characteristic of the initial pulse can be obtained in an initial moment, and a characteristic of the subsequent pulse can be obtained in a subsequent moment, using an input indicative of the sensed movement from the optical sensing system. The measured blood pressure measurement can be obtained at a time of measurement closer to the initial moment than the subsequent moment.

In some implementations, the optical source and optical reffator can be configured to produce a granularity pattern output that changes in response to the relative movement of the optical source and the optical refractor.

In some implementations, the vital sign can be at least one of a heart rate, an arterial pulse waveform, a systolic blood pressure, a diastolic blood pressure, an average arterial blood pressure, a pulse pressure, and an arterial compliance .

In some implementations, generating the measurement of the vital signal may include determining a pulse amplitude from changes in the amount of optical energy received by the optical detector.

In some respects, a vital sign measurement device includes a sensor clamping device, an optical sensing system, and an output unit. The sensor fixation device is adapted to be placed against an anatomical location of an individual, within which is an artery. The optical sensing system includes an optical source device and an optical detector, both attached by the sensor clamp and moving with the movement of the sensor clamp. The optical source device is configured to produce a granularity pattern output and the optical detector is positioned to detect at least a portion of the granularity pattern output and to generate, from there, the detected portion of the granularity pattern output. granularity. The optical sensing system can sense an arterial pulse from moving, folding, or compressing at least a portion of the optical sensing system in relation to other portions of the optical sensing system, which can result in a change in the optical signal received within the detected portion of the granularity pattern output. The output unit generates a vital signal measurement using a signal indicative of the received optical signal within the detected portion of the granularity pattern.

In some implementations, the sensor clamping device may be an inflatable pneumatic balloon. In some implementations, the vital sign measurement device may include a pressure sensor to detect pressure applied to the anatomical location. In some implementations, the output unit can receive, from a pressure sensor, a pressure input indicative of the pressure applied to the anatomical location and generate a vital signal using the input of the optical sensing system and the pressure input.

In some implementations, the individual's anatomical location is an upper arm, and the sensor fixation device is configured so that the optical sensing system is positionable to sense movement due to a pulsation of a brachial artery.

In some implementations, the optical source device may include an optical source and a diffuser that diffuses an optical signal produced by the optical source to produce the output of the granularity pattern. For example, the diffuser can include polyoxymethylene, a white fluoropolymer, polyamide, or a combination of these. In some implementations, the optical signal can travel through a portion of the diffuser having a thickness between 0.2mm and 1.0mm.

In some implementations, the optical source device may include an optical source and a mirror with surface imperfections that refracts an optical signal produced by the optical source to produce the granularity pattern.

In some implementations, the vital sign measurement device may include a spatial optical occluder adapted to prevent the optical detector from receiving a portion of the granularity pattern output. For example, the spatial optical occlusion may be a blocking structure having an optical hole formed therein.

In some implementations, the optical detector may have an optical energy receiving portion having a smaller surface area than the exit area of ​​the granularity pattern. For example, the detected portion of the granularity pattern can be 100 times smaller than an area of ​​an average granule of the granularity pattern. In some implementations, the detected portion of the granularity pattern can be between 1 and 25 times the area of ​​an average granule of the output of the granularity pattern.

In some implementations, the optical source includes a coherent light source.

In some implementations, the optical detector may include a plurality of optical detection regions, each optical detection region adapted to receive optical energy from the granularity pattern of a plurality of detected regions from the output of the granularity pattern. In some implementations, the optical detector can be a CCD or CMOS detector.

In some implementations, the vital sign can be at least one of a heart rate, an arterial pulse waveform, a systolic blood pressure, a diastolic blood pressure, an average arterial blood pressure, a pulse pressure, and an arterial compliance .

In some implementations, the vital sign measurement device may include a spring attached to at least a portion of the optical sensing system to oppose a force from the arterial pulse and return the optical sensing system to an initial state after the pulsation arterial. In some implementations, the vital sign measurement device may include a sensor block attached by the sensor fixation device adjacent to the anatomical location. The modulation of the sensor block can result in relative movement, compression, or folding of portions of the optical source which can result in a modulation of the output of the granularity pattern.

In some implementations, the optical sensing system can be adapted to sense a pulse amplitude of the arterial pulse from the movement, bending, or compression of at least a portion of the optical sensing system in relation to other portions of the optical sensing system , which can result in a series of changes in the detected portion of the granularity pattern output. In some implementations, the optical sensing system can be configured to sense optical signals representative of a series of arterial pulsations and the output unit can be adapted to determine a pulse waveform for each of the series of arterial pulsations.

In some ways, a method of measuring a vital sign in an individual may include placing a sensor fixation device against an individual's anatomical location, generating a pattern of granularity using an optical source device attached by the fixation device. sensor, detecting, using an optical detector attached by the sensor fixing device, a portion of the output of the granularity pattern and generating, from it, a signal indicative of the optical energy received in the detected portion of the granularity pattern, the detected portion of the granularity pattern changing in response to an arterial pulse, and generating a vital sign measurement using the indicative signal generated from the optical energy received in the detected portion of the granularity pattern.

In some implementations, the vital sign can be at least one of a heart rate, an arterial pulse waveform, a systolic blood pressure, a diastolic blood pressure, an average arterial blood pressure, a pulse pressure, and an arterial compliance .

In some implementations, the vital sign measurement may include detecting a number of fluctuations in the optical energy received by the optical detector during an arterial pulse. In some implementations, the generation of the vital sign measurement using the sensed motion indicative input may include considering the time derivative of the sensed motion indicative input.

In some respects, a vital sign measurement device includes a sensor clamping device, an optical sensing system, and an output unit. The sensor fixation device is adapted to be placed against an anatomical location of an individual, within which is an artery. The optical sensing system includes an optical source, a diffuser, and an optical detector. At least one of the optical source, the diffuser, and the optical detector is attached by the sensor clamping device and adapted to move in response to an arterial pulse in relation to at least one of the other components of the optical sensing system. The optical source and diffuser are configured to produce a pattern of granularity. The optical detector is positioned to sense a portion of the output of the granularity pattern and to generate, from there, a signal indicative of the optical energy received within the detected portion of the granularity pattern. The output unit generates a vital signal measurement using the indicative signal generated from the optical energy received within the detected portion of the granularity pattern.

Details of one or more embodiments of the invention are presented in the accompanying drawings and in the description below. Other features, objectives, and advantages of the invention will be apparent from the description, drawings, and claims.

DESCRIPTION OF THE DRAWINGS

Fig. 1 represents an implementation of the vital sign measurement device.

Figs. 2A, 2B, and 2C represent various implementations of the vital sign measurement device positioned on an upper arm, and showing three different levels of pneumatic balloon pressure in relation to systolic blood pressure.

Fig. 3 represents an implementation of a vital sign measurement device having a sensor fixation device with an inflatable bladder.

Fig. 4 represents a series of pulsations during the deflation of a pneumatic balloon detected by a pressure sensor pneumatically attached to the pneumatic balloon, compared to the pulsations obtained simultaneously, detected by an optical sensing system attached by a sensor fixation device.

Figs. 5A, 5B, and 5C represent an implementation of an optical sensor housing containing the components of an optical sensing system.

Figs. 6A, 6B, and 6C represent an implementation of an optical sensor housing containing the components of an optical sensing system.

Figs. 7A and 7B represent a pattern of granularity produced by an optical source device including an optical source and a waveguide.

Figs. 8A and 8B represent a pattern of granularity produced by an optical source device including an optical source and a diffuser.

Figs. 9A, 9B, and 9C represent implementations of the optical sensing system including a spatial optical occluder.

Figs. 10A, 10B, and 10C represent implementations of the optical sensing system including an optical detector with a plurality of optical sensing regions.

Figs. 11A, 11B, and 11C represent patterns of granularity produced by various implementations of the vital sign measurement device.

Fig. 12 represents an electrical signal produced by an optical detector that receives a portion of a pattern of granularity modulated by an arterial pulse.

Fig. 13 depicts an implementation of an optical detector having a plurality of optical detection regions each producing electrical signals.

Figs. 14A, 14B, and 14C represent implementations of different analytical methods used to determine one or more vital signs by the output unit.

Same reference symbols in the various drawings indicate similar elements.

DETAILED DESCRIPTION

As shown in fig. 1, a vital sign measurement device may include a sensor clamping device 102, an optical sensing system 104, and an output unit 106. An output from the optical sensing system 104 can be used to determine the measurement of a vital sign. The sensor fixation device 102 can be placed against an anatomical location of an individual 112, within which is an artery 118. The optical sensing system 104 can be positioned to sense the motion corresponding to an arterial pulse when the sensor fixation device 102 is placed against the anatomical location of the individual 112. The optical sensing system 104 can include an optical source 202, a optical refractor 212, 214, or 216 and an optical detector 240, all attached by the sensor clamp 102 and moving with the movement of the sensor clamp 102. An output unit 106 can receive input data from the optical sensing system 104 which is indicative of movement corresponding to an arterial pulse and can generate a measure of a vital signal. The optical sensing system 104 can sense an arterial pulse from the movement, folding, or compression of at least a portion of the optical sensing system in relation to other portions of the optical sensing system which results in changes to the optical signal received by the optical detector.

For example, a vital sign may include a heart rate, an arterial pulse waveform, a systolic blood pressure, a diastolic blood pressure, an average arterial blood pressure, a pulse pressure, and / or a measure of arterial compliance. In some implementations, vital signs can be determined from the time of arterial pulsations, the amplitude and / or value of arterial pulsations, or from the wave forms of arterial pulsations. In some implementations, vital signs can be determined from the output received from the optical sensing system 104 alone or in combination with other data (for example, data relating to pressure inside a pneumatic balloon). For example, in some implementations, a heart rate can be determined from the output received from the optical sensing system 104, alone.

Sensor Fixture

The sensor fixation device 102 can be any structure adapted to secure and position an optical sensing system 104 or a portion thereof, adjacent to an anatomical location of an individual 112, so that the optical sensing system 104 can detect a pulse arterial. The sensor clamping device 102 can secure the optical sensing system 104 adjacent to an individual's anatomical location 112 at a predetermined sensor clamping pressure or an adjustable sensor clamping pressure. For example, the sensor clamping device 102 can be an adhesive bandage or an air balloon (for example, an elastic air balloon or an inflatable air balloon). In some implementations, the sensor clamping device 102 can be an inflatable pneumatic balloon 120 having an inflatable bladder 122. Bladder 122 can be connected pneumatically to a pump 124 via a hose 116. In some implementations, the sensor clamping device 102 can apply pressure to an individual's anatomical location 112. For example, a pneumatically inflatable air balloon can be inflated (for example, via pump 124) and deflated (for example, via valve 126) to adjust the pressure applied to a portion of the individual's body 112. In some implementations, the device may include a pressure transmitting device (e.g., an inflatable pneumatic balloon) adapted for placement close to the placement of the sensor clamping device 102, which secures the optical sensing system 104.

The sensor clamping device 102 can be applied to any portion of an individual's body. In some implementations, the sensor fixation device 102 is dimensioned and arranged for placement in an anatomical location of an individual's body adjacent to an individual's predetermined artery 118. As shown in figs. 2A, 2B, and 2C, the sensor fixation device 102 can be positioned over an upper arm (above an individual's elbow), so that the optical sensing system 104 can sense the movement corresponding to an arterial pulse , in the brachial artery 118. The sensor fixation device 102 can also be adapted for placement on the wrist, so that the optical sensing system 104 can sense the movement corresponding to an arterial pulse in the radial artery. The sensor fixation device 102 can also be positioned on a leg (for example, on the ankle, to detect pulsations in an artery), on the neck, or on any other part of the body where an arterial pulse can be detected.

As shown in figs. 2A, 2B, and 2C, the optical sensing system 104 can be positioned close to the midpoint of the sensor fixture 102 (as shown in Fig. 2A), at the midpoint of the sensor fixture 102 (as shown in Figures 2B and 2C), or away from the midpoint of the sensor clamping device 102 (not shown). The placement of the optical sensing system 104 within the fixture and sensor 102 may impact the data obtained. In some implementations, pressure applied to an artery that is below the surface of an anatomical location may be non-uniform. For example, although a body delivery device 102 can apply uniform pressure, the pressure transmitted through the tissue layers can result in non-uniform pressure against an artery that is some distance below the surface. In some implementations, the pressure applied to an artery that is some distance below the skin, by an inflatable pneumatic balloon, may be higher in the median plane of the pneumatic balloon and lower at the edges of the pneumatic balloon. The location of the optical sensing system 104, in relation to the sensor fixation device 102, can be fixed to optimize the sensitivity of selecting arterial pulse characteristics. In some implementations, the optical sensing system 104 can be located in the median plane of the pneumatic balloon so that it does not respond to the pulsatile enlargement of the arterial segment under the proximal part of the pneumatic balloon, when the pressure of the pneumatic balloon exceeds the systolic pressure, allowing thus, an accurate determination of systolic pressure when the middle section of the arterial segment opens.

In other implementations, the optical sensing system 104 can be located near the distal edge of the pneumatic balloon that specifically responds to changes in the pulsatile arterial dimension in that position. Consequently, the unique characteristics of the arterial pulse waveform in diastolic pressure, in a distal position, can be identified, and the effects of arterial conformity, in more distal arteries, can be detected. Flexing, out of the skin, in the median plane of the pneumatic balloon, and also away from the median plane, occurs during systole, when the pressure of the pneumatic balloon is below the systolic pressure. At pneumatic balloon pressures that exceed systolic blood pressure, arterial oscillations are limited to the proximal area of ​​the pneumatic balloon, as discussed above. In some implementations, the optical sensing system 104 can be located on a body clamping device 102, separate from a pressure transmitting device adapted to be placed against a second anatomical location of an individual close to the anatomical location of the clamping device. sensor 102, to allow detection of arterial pulsation by the optical sensing system in a distal and separate position from the pressure transmitting device. For example, the pressure transmitting device may be an inflatable pneumatic balloon. In some implementations, both the pressure transmitting device and the body clamping device 102 can be inflatable clamps.

Fig. 2A represents a sensor fixation device 102 transmitting a pressure on the arm exceeding the arterial systolic pressure of the brachial artery, enough to result in a minimal arterial opening under the leading edge of the sensor fixation device 102 in the systole. The amount of pressure transmitted against the sensor clamping device 102 will pulse slightly due to arterial expansion at the leading edge during an arterial pulse. No arterial opening occurs in the positioning of the optical sensing system 104, and, consequently, the optical sensing system 104 does not produce a pulsatile signal. However, a pulsatile signal will occur at a higher pressure if the optical sensing system 104 is located at a position close to the midpoint of the sensor fixture 102 than if it were located at the midpoint of the sensor fixture 102.

Fig. 2B represents a sensor fixation device 102 transmitting a pressure slightly exceeding the arterial systolic pressure, so that the arterial opening 118 extends almost to the midpoint of the sensor fixation device 102 in the systole. The oscillation in the pressure transmitted against the sensor fixation device 102 during an arterial pulse pressure would be much greater than in the case of fig. 2A, since arterial expansion occurs over almost half of the segment located within the sensor fixation device. However, no arterial opening occurs at the midpoint of the sensor fixation device 102, and therefore the optical sensing system 104 does not produce a pulsatile signal.

Fig. 2C represents a sensor fixation device 102 transmitting a pressure below systolic blood pressure, so that the entire segment of artery 118 opens momentarily in the systole. The pressure fluctuations transmitted against the sensor clamp 102 during an arterial pulse will be even greater in amplitude. The arterial opening in the position below the optical sensing system causes the optical sensing system to register a pulsatile signal.

Fig. 3 represents an implementation of a sensor clamping device 102. The sensor clamping device can be an inflatable pneumatic balloon 120 having an inflatable bladder 122. The inflatable pneumatic balloon 120 can be adapted to be wrapped around the upper arm of an individual to allow the optical sensing system 104 to detect arterial pulsations from the brachial artery. The components of the optical sensing system 104 can be housed within an optical sensor housing 200 located at the midpoint 134 of the pneumatic balloon 120. The pneumatic balloon 120 may include hook and loop fasteners 132 (for example, Velcro®) or others fixing devices that can be used to fix the pneumatic balloon 120 around a member of an individual. The pneumatic balloon 120 can be wrapped around an individual's limb and the bladder 122 inflated to transmit pressure on the limb. Bladder 122 can be connected to a pump 124 by a hose 116. Bladder 122 can also be attached to a valve 126 that can control deflation of bladder 122. Pressure in bladder 122 can be measured with a pressure transducer 128. The pressure transducer

128 it can be located in the bladder, as shown, or it can be pneumatically connected to bladder 122 (for example, via hose 116).

The top portion of fig. 4 represents pressure pulses sensed in a sensor fixation device 102 transmitted by the series of arterial pulsations when the pressure transmitted by the sensor fixation device 102 is reduced from a pressure that exceeds an individual's systolic blood pressure to a pressure below diastolic blood pressure of an individual. The bottom portion of fig. 4 represents the pulsations determined from the optical sensing system 104 at the midpoint of the sensor fixture 102, when the pressure transmitted by the sensor fixture 102 is reduced from a pressure that exceeds an individual's systolic blood pressure to a pressure below an individual's diastolic blood pressure. As shown, the optical sensing system 104 does not detect any pulsations until the transmitted pressure is at or below systolic blood pressure. In some implementations, this may allow an accurate determination of systolic blood pressure.

Output Unit

Movements detected from the optical sensing system 104 can be transmitted via electrical wires 108 to a display device 114. In some implementations, as shown in fig. 3, electrical wires 108 can connect a pressure transducer 128 to a display device 114. An output unit 106 (not shown in fig. 3) it can be part of the display unit 114, it can be inside the optical sensor housing 200, it can be in another portion of the pneumatic balloon assembly, or it can be located remotely and in communication with the optical sensor system 104 through transmission wireless. In some implementations, output unit 106 can transmit vital signal measurements via wireless transmission. In some implementations, the optical sensing system 104 can transmit data regarding the amount of light received by an optical detector to an output unit 106 via wireless transmission. Output unit 106 may comprise a processor for determining the vital signal from the signals of the optical sensing system 104 with or without other data. In some implementations, as shown in Fig. 1, the output unit may include a display to display the vital sign. In some implementations, the output unit may include an alarm system to produce a human-detectable signal when a measurement of a vital signal generated by the output unit meets predetermined criteria. For example, the output unit can be adapted to create a visual or audio alert to alert a user that a detected vital signal is outside a predetermined range. Output unit 106 can perform a number of data processing steps, calculations, or evaluation functions, some of which will be discussed below.

Optical Sensing System

The optical sensing system 104 can include an optical source 202, an optical refractor 212, 214, or 216 and an optical detector 240, which can be attached by the sensor fixture 102 and move with the movement of the fixture fixture. sensor 102. In some implementations, the optical sensing system 104 may act as a motion sensing system (for example, a motion sensing system adapted to sense localized motion associated with an arterial pulse). The optical sensing system 104 can sense movement corresponding to an arterial pulse when the sensor fixation device is placed against the individual's anatomical location. As shown in figs. 5A, 5B, 5C, 6A, 6B, and 6C, an optical sensing system 104 can be contained within an optical sensor housing 200.

In some implementations, the optical sensing system 104 may include an optical source 202 optically attached to an optical refractor 212, 214, or 216, so that light waves travel from the optical source 202 to the optical refractor 212, 214, or 216. Optical source 202 may be a coherent light source, for example, a laser. In some implementations, an LED can be used as the 202 optical source.

In some implementations, the optical refractor may be an optical waveguide 212, a diffuser 214, a mirror with surface imperfections 216, or other refractive material. The movement, folding, or compression of the optical refractor 212, 214, or 216 can alter the path taken by the optical waves 218 that travel through the optical waveguide 212, through the diffuser 214, or by reffacting out of the mirror 216, making therefore, the amount of optical energy (e.g., light) received by the optical detector 240 or 242 changes. Likewise, moving the optical source 202 or optical detector 240 or 242 can result in changes in the amount of optical energy (for example, light) received by optical detector 240 or 242. Monitoring changes in the amount of optical energy received, an arterial pulse can be characterized, which can be used to determine a vital sign. For example, the pulse width can be determined, or the shape of the pulse waveform can be determined.

In some implementations, optical detector 240 or 242 may be a PIN diode photodetector, a CCD (Attached Load Device) detector, or a CMOS (Complementary Metal-Oxide Semiconductor) detector. In some implementations, the optical sensing system 104 may include one or more optical detectors 240 or 242. For example, in some implementations, a series of optical detectors may each receive optical energy refracted by the optical refractor 212, 214, or 216. In some implementations, an optical detector 242 can include a plurality of optical detection regions. For example, CCD and CMOS detectors can be configured to allow detection of the amount of optical energy received by a plurality of discrete detection regions or can be configured to produce a signal indicating the total amount of optical energy received by the CCD or CMOS detector .

In some implementations, such as those discussed below, optical source 202 and optical refractor 212, 214, or 216 are arranged to produce a pattern of granularity. In some implementations, compression and / or folding of a compressible or flexible optical waveguide can result in a change in the total amount of light coming out of the optical waveguide or a change in the granularity pattern.

Figs. 5A, 5B, 5C, 6A, 6B, and 6C show examples of miniaturized optical sensor housings that can be placed against an individual's skin to sense arterial pulsations. The optical sensor housing 200, as shown, includes a sensor block 232, a spring 234 attached to the sensor block 232, an optical source 202, an optical refractor 212, 214, or 216, an optical detector 240 or 242, and wires 108 from optical detector 240. In some implementations, the optical sensor housing 200 may also include additional elements, such as a spatial optical occluder 222 (e.g., a pin hole) between the optical refractor 212, 214, or216, and the optical detector 240 or 242, as shown in fig. 5C. In some implementations, the sensor housing 200 may have a width of between 1,778 and 3,302 cm (for example, approximately 2,54 cm), a length between 3,81 and 5,588 cm (for example, approximately 4,318 cm), and a thickness between 0.762 and 3.048 cm (for example, approximately 1.524 cm).

As shown in figs. 5A, 5B, SC, 6A, 6B, and 6C, a sensor block 232 adapted for placement against an anatomical location of an individual can be attached to a spring 234. The sensor block 232 can extend outside the optical sensor housing 200 when in a relaxed state. For example, the sensor block 232 can extend outside the optical sensor housing 200 by at least 0.254 cm (for example, between 0.254 and 0.762 cm). As shown, the sensor block 232 extends outside the housing sensor 200 by 0.40894 cm. The sensor block 232 can be of any shape. The sensor block 232 can have a diameter of at least 0.762 cm, for example, between 0.762 and 2.032 cm (for example, approximately 1.524 cm). In some implementations, for example, as shown in fig. 6C, the sensor block 232 can be attached to the spring 234 by an articulation 236 that allows forward and backward movement of the sensor block 232. In some implementations, as shown in fig. 6C, the sensor block 232 may have an inclined top surface.

Sensor block 232 can be attached, or otherwise positioned, to cause relative movement of optical source 202, optical refractor 212, 214, or 216, any spatial optical occlusion 222, if used, optical detector 240, or a combination of these . As shown in fig. 6C, the sensor block 232 may include a pressure portion 238 adapted to cause folding, compression, or movement of an optical waveguide 212. In some embodiments, as shown in fig. 5C, spring 234 can be attached to an optical source 202, so that modulation of spring 234 causes movement of the optical source 202 while the optical refractor 214 remains stationary. The spring 234 can have a length of at least 1.524 cm, for example, between 1.524 cm and 4.572 cm (for example, 2.794 cm). Various other configurations may allow the modulation of spring 234 to result in relative movement of the optical source 202 and the optical refractor 212, 214, or 216.

The sensor block 232 can also be positioned within a cutout 252. The spacing between the cutout 252 and the sensor block 232 can impact the amount of movement of the sensor block 232 allowed by the sensor housing 200 due to arterial pulsations. The spacing between the cutout 252 and the sensor block 232 can be approximately 0.254cm.

Wires 108 can transmit data from optical detector 240 or 242 to an output unit 106, as discussed above. In some implementations, the output unit can be included within the optical sensor housing 200 and wires 108 can transmit vital signal data to devices outside the housing 200. In some implementations (not shown), the optical sensing system 104 can transmit data from a housing 200 by wireless transmission.

Granularity Pattern

Figs. 7A, 7B, 8A, and 8B represent the basic principle of modulating the granularity pattern. An optical source 202 can be optically attached to an optical refractor 212, 214, or 216, so that optical waves 218 travel from optical source 202 to optical refractor 212, 214, or 216. Optical source 202 can provide coherent light . Optical source 202, like a laser, can be used to illuminate optical refractor 212, 214, or 216 to create a pattern of granularity 260, so called because the optical effect, in the illumination of the distant field, is in the appearance of 262 granules For example, the optical refractor may be the optical waveguide 212, a diffuser 214, a mirror with surface imperfections 216 (for example, as shown in Figs. 9C and 10C), or other refractive material capable of forming a pattern granularity 260. Refraction can cause spatial variations in the transmitted optical waves 218 that appear as regions of darkness on a light background. These dark regions, or granules 262, may be characteristic, but of random shape and size, determined by the refractive characteristics of the optical refractor 212, 214, or

216. The optical waves 218 (only a few of which are illustrated) that illuminate the optical refractor 212, 214, or 216 can interfere constructively to form a granularity pattern 260 of a series of granules 262. The relative movement, folding, or compression of the optical refractor 212, 214, or 216 in relation to the optical source 202 alters the path followed by the optical waves 218 moving through the optical refractor 212 or 210 or refracting out of the refractor 310, making , thus, the granularity pattern 260 changes. For example, when an optical refractor 212, 214, or 216 is moved relative to optical source 202, the granularity pattern 260 may appear to flicker or, in some cases, appear to rotate. Although the total light traveling through the optical refractor 212 or 210, or refracting out of the mirror 216, can remain relatively constant, monitoring a selected detected portion, for example, 264, of the granularity pattern, changes the amount of energy optics (for example, light) in a detected portion 264, if the granularity pattern 260 can be observed. By monitoring changes in the amount of light in the detected portion, for example, 264, the amount and / or speed of relative movement, bending, or compression can be determined.

The detected portion, for example, 264, can be limited by restricting the portion of the formed granularity pattern 260 allowed to be received by the optical detector 240 or 242. Restricting the portion of the granularity pattern 260 received by an optical detector 240 can be achieved in several ways. For example, as shown in the fi Figs. 9A, 9B, and 9C, a spatial optical occluder 222, such as a locking structure having an optical hole formed within it (for example, a pinhole hole), can be positioned between the optical refractor 212, 214, or 216 and an optical detector 240. In some implementations, the detected portion 264 of the granularity pattern 260 can be restricted using an optical detector 240 having an area of ​​reception of optical energy smaller than the area of ​​the produced granularity pattern 260. Optical detector 240 or 242, and any used intermediate spatial optical occlusion 222, can be placed adjacent to optical refractor 212 or 214, to ensure that optical detector 240 or 242 receives light only from granules within a predetermined detected portion, for example , 264. When using a mirror with surface imperfections 216 as the optical refractor, moving away from the optical detector 240 and any intermediate spatial optical occlusion used will determine the size of the detected portion 264 and the granularity pattern produced 260.

Optical source 202 can be a coherent light source, for example, a laser.

The optical refractor may be an optical waveguide 212, a diffuser 214, or a mirror having surface imperfections 216, or another refractive material capable of forming a 260-grain pattern. In some implementations, a device may use a combination of elements multiple and / or different optical. For example, an optical waveguide 212 can be used to guide light waves 218 to a diffuser 214.

An optical waveguide 212 can be an optical fiber or any liquid, gel, or solid that transmits light waves by internal reflection or refraction. In some implementations, the optical waveguide 212 can transmit almost 100% of the light providing almost total internal refraction. For example, an optical waveguide 212 may include an optical material with a relatively high refractive index (n_H), surrounded by a material with a lower refractive index (n]). In these 212 optical waveguides, light is lost only when the light wave reaches the interface between the two materials at an angle less than the critical angle (0_Ç). The critical angle (0_Ç) can be calculated by the following equation.

0_Ç = arcsen (n] / n_H)

In some implementations, the surrounding material with the lowest shrinkage index may be air. In some implementations, the waveguides may also be in the form of a hollow tube with a highly reflective inner surface. The internal surfaces can be polished metal.

In some implementations, such as those shown in figs. 7A and 7B, an optical waveguide 212 causes internal reflection of the optical waveguides 218 within the core of the optical waveguide 212. When the optical waveguide 212 is moved or bent, the path for each light wave 115 is changed , resulting in changes in a resulting granularity pattern. In some implementations, the optical waveguide 212 may be a flexible waveguide. In some implementations, the optical waveguide 212 may be a compressible waveguide.

A diffuser 214 can be any device comprised of refractive material that diffuses, spreads, or scatters light in some way, such as any semitransparent liquids, gels, or solids; airborne particles; or, and skin, or other tissue. For example, a diffuser 214 can include polyoxymethylene (POM) (for example, Delrin® acetal resin), white fluoropolymer (for example, Teflon® fluoropolymer), polyamide (PA) (Nylon®), or sandblasted or opaque glass. In some implementations, the diffuser material may have low optical absorption at the laser wavelength, and may have refractive properties that produce sufficient light scattering over a short path length, to insure that the granularity pattern will be generated on the opposite surface laser, with appropriate granule size and uniformity. For example, the diffuser may include a part of polyoxymethylene (Delrin® acetal resin) having a thickness between 0.2mm and 1mm (for example, between 0.4 and 0.6mm), so that the optical intensity is not decreased excessively on the outlet side, but that is thick enough to effect the light scattering needed to create the 260 granularity pattern.

In some implementations, such as those shown in figs. 8A and 8B, a diffuser 214 causes refraction of light waves within the body of diffuser 214. Refraction of light waves within the diffuser can be caused by variations in the refractive index within diffuser 214 that result in random photon dispersion . When the diffuser 214 is moved, the areas of the diffuser that cause the refraction of the light waves are also moved causing the optical waves 218 to refract differently within the diffuser 214, resulting in changes in a resulting granularity pattern 260.

In some implementation, as shown in figs. 9C and 10C, the optical element can also be a mirror with surface imperfections 216. Imperfections in the mirror can result in light waves impacting the imperfections to reflect at different angles. Reflection of light outside the imperfections of mirror 216 can also result in an optical pattern 260. The relative movement of mirror 216, relative to optical source 202, similarly results in changes in optical pattern 260.

In some implementations, the characteristic size and number of individual granules 262 can be controlled. For example, the characteristic size and number of individual granules 262 can be controlled with an optical waveguide 212 having the optimum diameter and refractive characteristics for the desired characteristics of granule 125. Illustrated in figs. 11A and 11B are granule patterns 260 of a laser 202, the beam of which is passed through different optical fibers. In fig. 11 A, a pattern of granularity with relatively few, large granules 262 is shown, which is formed from an optical waveguide 212 having a small diameter and small refractive index gradient. In contrast, the granularity pattern 260 shown in fig. 11B, with relatively many small granules 262, is formed with an optical waveguide 212 that allows for much more optical interference because of a larger diameter and a higher refractive index gradient, resulting in a granularity pattern 260 with relatively many , small granules 262.

Similarly, fig. 11C is an enlargement of a granularity pattern 260 formed by passing coherent light through a diffuser 214. The bar on the upper right side of the figure indicates the size of the magnification.

In some implementations, the average granule size of the sampled portion of a 260 granularity standard can be at least 10 microns (for example, between 25 and 100 microns).

The sensitivity of the relative movement, folding, or compression of the optical source and the optical refractor 212, 214, or 216 can be optimized by correctly dimensioning the detected portion 264 and fixing the separation of the optical refractor 212, 214, or 216, from the detector optical 240, and any intervening spatial optical occlusion 222, if used. The detected portion 264 can be dimensioned in relation to the average granule size in order to optimize the amplitude of the fluctuations in the electrical output of the optical detector 240, which correspond to the modulation of the granularity pattern 260 that is caused by the relative movement, bending, or compression optical refractor 212, 214, or 216, optical source 202, or optical detector 240 or 242. For example, sizing a hole in a 222 spatial optical occlusion to collect only a small number of granules, such as less than one percent of the area of ​​the granularity pattern 260, and employing appropriate signal processing for the detector output optical variable in time, the time derivative of the pulse signal can be measured to allow a calculation of a vital signal. In some implementations, the optical energy receiving portion of the optical detector 240 may also have a smaller area than the area of ​​the produced granularity pattern 260.

In some implementations, the detected portion 264 of the granularity pattern 260 can be less than one hundred times the average granule size, for example, between 1 and 25 times the average granule size. In some implementations, optical detector 240 can receive up to an average of 50 granules, for example, between 1 and 5 granules. For example, a pinhole orifice having a diameter of 125 microns, can be used to restrict the detected portion 264 of the granularity pattern 260 received by an optical detector 240 or 242.

Analytical Methods

Optical detector 240 or 242 of an optical sensing system 104 can generate an electrical signal 420 that indicates the amount of light received. Electric signal 420 may be a function of time. The electrical signal from optical detector 420 is analyzed to determine the rate of modulation of the granularity pattern 260. For example, fig. 12 represents a possible electrical signal 420 that indicates modulation in an amount of optical energy received by an optical detector 240 or 242. As shown in fig. 12, the amount of light received by the optical detector 240 may fluctuate. The frequency of oscillation of the optical energy received by the optical detector 240 or 242 can generally be understood as the inverse of the amount of time that a characteristic change occurs in the number or in the brightness of the granules, within the predetermined detected portion, for example, 264, which is received by optical detector 240 or 242. A characteristic change that occurs in the brightness number of the granules can generally be scaled to represent a characteristic of the relative movement, bending, or compression of the optical source and the optical refractor. By monitoring the oscillation rate of the amount of light received by the optical detector 240, the amplitude and / or value of an arterial pulse can be determined.

In some implementations, the average amount of light received by the optical detector 240 can vary over time in response to the positioning of the light source in relation to the optical refractor 212, 214, or 216 and, the amount of light received by the optical detector 240 can oscillate over that average amount of light received, due to the relative movement of the optical source and the optical refractor.

In some implementations, this low frequency variation in the amount of light received can be filtered out of the received signal. In some implementations, high frequency noise can also be filtered out. In some implementations, variations in high and / or low frequency, in the amount of light received by an optical detector, can be filtered out of the signal from an optical detector 240 or 242, before determining a vital signal from the Dice. In some implementations, signal filtration can be performed by an optical waveform prefilter 432.

Output unit 106 can determine the amplitude and / or value of each arterial pulse to determine one or more vital signs. In some implementations, the amplitudes and / or values ​​for a series of arterial pulsations can be determined to determine one or more vital signs. For example, to determine the amplitude and / or value of an arterial pulse from oscillations in the amount of light received by the optical detector 240, an electrical differentiation circuit can be applied to an output of the optical detector 240 to produce a signal proportional to the its time derivative, dE / dt. This time derivative signal can increase in proportion to the frequency content of the optical detector's electrical signal, which is proportional to the rate of modulation of the granularity pattern. Each arterial pulse (which corresponds to a cardiac cycle) may, for example, characteristically exhibit an increase in pressure, followed by a decrease in pressure, and then an inactive period before the start of the next pulse. Increasing the pressure can cause the optical source 202 to move or the optical refractor 212, 214, or 216 to move, bend, or compress so that the 260 module granularity pattern, the modulation rate will increase at the beginning of pulsation and will be reduced to zero at the moment of the maximum pulse pressure (that is, where the pulse wave stops rising, and is almost on the point of beginning its descent). When the pressure decreases, an opposite movement of the waveguide will occur, again modulating the pattern of granularity, so that its modulation rate increases after the maximum pulse pressure and, drops to zero, when the arterial pulse ends. Fig. 12 represents an example of an electrical signal from the optical detector created by an arterial pulse. The dE / dt signal will therefore start at zero, then increase to a maximum, then decrease to zero, increase again, and finally decrease to zero, all during the course of an arterial pulse. The pulsation amplitude can be, as a first approximation, proportional to the maximum modulation rate of the granularity pattern, which in turn can be calculated from the maximum value of dE / dt, based on the relationship between a sinusoidal function and its derivative, ie is:

dE / dt = d / dt [sen (cot)] = cocos (cot), whose maximum amplitude is proportional to the maximum modulation rate during the arterial pulse cycle, or (ü_max.

The dE / dt signal can be analyzed with a real-time spectrum analyzer, such as a digital signal processor (DSP), to determine the maximum frequency during the arterial pulse cycle. The maximum frequency, cú_max, occurs at the maximum of dE / dt, and similarly according to the pulse amplitude. The highest dominant frequency, ®max can be used for the analysis or, if a frequency range is present, the first, second, or other moment in the frequency spectrum can be used.

The output of optical detector 240 can also be connected to AC and powered by a signal exchange detector, which provides a count of the number of signal exchange events per unit of time (a signal exchange rate) and a total count signal exchange events during an arterial pulse (the signal exchange count). By correctly limiting the size of the detected portion 264, the instantaneous signal exchange rate is easily shown to be proportional to the modulation rate of the granularity pattern 260. An algorithm can be applied to sense the rise in the signal exchange rate above zero, and then count the number of signal exchanges until the signal exchange rate returns to zero. A threshold slightly above zero can be used, in place of a true signal exchange rate, to account for noise. Alternatively, high frequency noise can be filtered out of a signal, from optical detector 240 or 242. The count can be repeated after the signal exchange rate rises above zero again, until it returns to zero . This cycle, including two counts of signal exchange, is considered to correspond to an arterial pulse. The two counts, taken from the mean, can be proportional to the amplitude of the waveguide's oscillatory movement in connection with the arterial pulse, and consequently they can also be proportional to the amplitude of the arterial pulse. An algorithm can be applied to the signal exchange rate that measures the time that this rate remains at zero between non-zero episodes. In a sequence of arterial pulsations, a relatively longer time can occur between the end of an arterial pulse and the beginning of the next. A relatively shorter time can occur at the maximum pulse pressure, where the pressure stops rising and starts to decrease, at which the signal exchange rate can be momentarily zero.

In some implementations, the dE / dt signal can be passed through an integration circuit and be integrated over time from its rise above zero until it returns to zero. This time corresponds to half the cycle of the arterial pulse, which can be determined by separately measuring an average value in the time of dE / dt to determine when it starts, and returns to zero. The resulting integration can be proportional to the amplitude of the waveguide's oscillatory movement, and can also, consequently, be proportional to the amplitude of the arterial pulse. This integration of the first derivative of an individual's position during a specified period of time can produce a result proportional to the change of position during the specified period of time.

In some implementation, as shown in figs. 10A, 10B, and 10C, a plurality of optical sensing regions 244 can be used. These optical detection regions 244 can be part of an optical detector 242 that contains a number of discrete optical detection regions 244. For example, optical detector 242 can be a CCD (Attached Load Device) or CMOS (Complementary Semiconductor) detector. Metal-Oxide). Each optical sensing region 244 can be configured to receive only a restricted portion of a granularity pattern 260, for example, as shown in Figs 10A, 10B, and 10C. Using a plurality of optical sensing regions 244 one can obtain data that more reliably represents the relative amplitudes of a series of pulse pressure waveforms. In some implementations, the output of a plurality of optical sensing regions 244 can each be connected to AC and powered by a switched signal detector. The electrical signals 420 corresponding to the different optical detection regions 244, as shown, for example, in Fig. 13, can be compared at the end of each arterial pulse or at the end of each blood pressure measurement cycle, to determine which has highest signal quality. The quality of an electrical signal 420 can also be determined by detecting a signal change count for each signal. For example, electrical signal 420 with the highest count can be considered to have the highest signal quality. The different signal exchange counts for each of the different detectors (or subset of different detectors) can also be averaged for each arterial pulse to produce a more reliable estimate of the pulse amplitude.

In some implementations, the output of a plurality of optical detectors can each be attached to a differentiation circuit to measure dE / dt. The different dE / dt values ​​corresponding to the different detectors can be compared at the end of each arterial pulse or at the end of each blood pressure measurement cycle to determine which has the highest signal quality. For example, the one with the highest dE / dt value_max can be considered to have the highest signal quality. The average of the plurality of different dE / dt values, corresponding to the different detectors (or subset of different detectors), can also be calculated for each arterial pulse to produce a more reliable estimate of the pulse amplitude.

In some implementations, a CCD (Attached Load Device) or CMOS (Complementary MetalOxide Semiconductor) detector can be used as a single optical detector 240 or as a plurality of optical detection regions 244. A typical CCD or CMOS detector may have more of 1 million pixels, and those in consumer-grade digital cameras can be up to 8 million or more pixels, in a 1-cm rectangular sensor. Each pixel, or separately addressable sensing region, can function as a separate optical detection region 244. Bending can also be used to effectively enlarge the detector's sensing areas by combining the outputs of an NxM group of pixels (for example, 2x2, 2x3, 3x3, etc.). In some implementations, the size of the detected portion 264 for each optical detection region 244 can be dynamically adjusted by binning. For example, during the life of a sensor the optical characteristics of the optical refractor 212, 214, or 216 can change and the size of the binned pixel group can be dynamically adjusted over the life of the optical sensing system 104 to re-optimize the size of the detected portion 264. In some implementations, each group of pixels that acts as an optical detection region 244 can be the same, or different sizes, which can be optimized depending on the portion of the 260 grain pattern received by that group of pixels. The use of a 240 or 242 CCD or CMOS optical detector may allow a device without an optical hole to be placed between the optical element and the CCD or CMOS optical detectors, due to the small size (typically 2-5 microns across) of CCD pixels and CMOS, results in an automatic limitation in the area of ​​the detected portion 264 of the granularity pattern 260.

In some implementations, the plurality of CCD or CMOS detectors can be in an lxN array of individual pixels or combinations of binned pixels. For example, figs. 10A, 10B, and 10C represent a 1x8 arrangement and fig. 13 represents a 1x4 arrangement. In addition, as shown in fig. 13, digital signal processing can be performed on each of the n separate digital outputs 420. Each digital output 420 can contain information about the modulation of the optical pattern in a different detected portion 264 of the granularity pattern 260, observed for each optical detection region 244. Each analysis of the digital signal processing can provide, in real time, an evaluation modulation rate (analogous to dE / dt) in one of the detection regions, and can be used to determine the maximum modulation rate during each arterial pulse. The average of the n measurements can be calculated for each arterial pulse to produce a more reliable estimate of the pulse amplitudes and the pulse amplitude envelope.

In implementations using a CCD optical detector or

CMOS 240 or 242 (as a single optical detector or as a plurality of detectors), an average optical detector output level can be adjusted and defined as a threshold. The individual signals from the detector can be measured with sufficient frequency (typically 100-2000 times per second) to resolve the modulation of the granularity pattern. The rate of true data can be dependent on the characteristic size of the bead in relation to the detector area (s) and the rate of movement of the optical element in relation to the light source. Each threshold crossing, defined as an occurrence in which the difference between a detector output measurement and the threshold is of opposite polarity to that of the subsequent detector measurement and the threshold, can correspond to a signal exchange. Threshold crossings can be counted and analyzed in a manner equivalent to the signal shift counts described above.

In some implementation, a digital signal processor (DSP) can be used to analyze the output of one or more optical detectors 240 or 244. Various methods of analyzing digital signal processing can be applied to determine modulation rates, including, but not in a limiting way, Fast Fourier Transformations (FFT), autocorrelations, and threshold crossing of digital CCD or digital CMOS outputs.

In FFT analysis, a signal can be analyzed to determine an average frequency using the following algorithm:

<ω> = JcirG (co) da), where ω is the angular frequency, Θ (ω) is the power spectrum, and j (co) dG) is normalized to a value of 1.

G (ω) is determined by the known convolution:

θ (ω) = [fg (t) -exp (- jcot) dt]², where g (t) is the time-varying signal, or, in this case, the E output of the optical detector

During each arterial pulse, the value of <ω> may rise and fall in proportion to the dE / dt signal described above. Consequently a value of <o>_max it can indicate the maximum modulation rate within a given arterial pulse cycle, and can be scaled and used to generate an envelope of the pulse width for use in determining systolic, diastolic, and mean arterial pressures.

In some implementations, an autocorrelation method can be used to determine the pulse amplitude and the pulse amplitude envelope. In autocorrelation, the signal can be auto-correlated according to the relationship:

<G (t)> = Jg (t) .g (tT) dt, where G (t) is the time delay autocorrelation function = τ, eg (t) is the time-varying signal. The value of G (0) is equal to the square root of the signal amplitude. The frequency spectrum is simply a convolution of the autocorrelation function, so that:

G (ω) = (1 / 2π) · JG (τ) · exp (-ja> T) dr.

Determining the average frequency of a time-varying signal using an autocorrelation method has been described previously and is not presented in more detail here. This calculation of G (co) is used to calculate the average frequency according to the same formula as in the FFT analysis:

<ω> = / ω · 0 (ω) όω,

In some implementations, the maximum dE / dt value can be calculated for each arterial pulse during a time interval when the pressure in the pneumatic blood pressure balloon constantly drops from a level above the systolic pressure, where the arterial pulse is absent . The start of each pulse is detected, during the time interval, by measuring and recording the periodic increase in dE / dt. For each pulse, the maximum value of dE / dt (dE / dt_max) can be recorded as a dimensionless number, and the pressure of the pneumatic balloon can also be recorded to allow the creation of an envelope of pulsation amplitudes in which the ordinate of the graph is dE / dt_max instead of the amplitude of the oscillation in mmHg. An algorithm can be applied to this envelope to determine systolic, diastolic, pulse, and / or mean arterial pressures.

In some implementations, the output signal exchange count of the AC-connected optical detector can be recorded for each arterial pulse for a period of time when the pressure, in an inflatable pneumatic balloon 120, constantly drops from a level above the systolic pressure, where the arterial pulse is absent. A series of arterial pulsations can be detected during the time interval and, for each pulse, the signal exchange count can be measured and recorded. For each pulse, the count (or average of two counts corresponding to the rise and fall of the arterial pulse) can be recorded, and the pressure of the pneumatic balloon can also be recorded to allow the creation of an envelope of the pulse amplitudes in which the ordinate of the graph is the signal exchange count instead of the amplitude of the oscillation in rnmHg. An algorithm can be applied to this envelope to determine the systolic, diastolic, pulse and / or mean arterial pressures.

In some implementations, the time interval between pulsations can be measured during a series of detected arterial pulses and used to determine the heart rate.

In some implementations, when the pressure of the pneumatic balloon is reduced, the systolic pressure can be determined to be a pressure of the inflatable pneumatic balloon 120 in which the first evidence of modulation of the granularity pattern occurs (that is, the rise in the exchange rate above zero, or the first appearance of a non-zero value for dE / dt). In some implementations, the diastolic pressure can be determined to be a pressure of the inflatable pneumatic balloon 120 in which a predetermined characteristic of the modulation of the granularity pattern occurs. For example, the last detected arterial pulse, where the last signal exchange rate has a non-zero value, or where the last non-zero value for dE / dt occurs and after which dE / dt remains at zero while the pressure of the pneumatic balloon drops even more, it can be considered as the diastolic pressure. Or the appearance of the first arterial pulse in a sequence of declining arterial pulsations where the dE / dt value_max is 50% of the maximum value of dE / dt_max (that is, the highest point on the pulse amplitude envelope). In some implementations, the mean arterial pressure can be determined to be an inflatable pneumatic balloon pressure 120 corresponding to the arterial pulse event in which the maximum signal exchange count, or the maximum dE / dt value_maxoccur (that is, the highest point in the pulse amplitude envelope).

In some implementations, the systolic pressure can be calculated to be at some pressure below the pressure of the pneumatic balloon in which, the first evidence of modulation of the granularity pattern occurs during deflation of the pneumatic balloon, based on an empirically determined algorithm, which calculates the contribution of some amount of artifact to the arterial pulsations acting against the optical sensing system 104, along with the other artifact related to electrical noise and modulation of the granularity pattern.

In some implementations, diastolic pressure can be calculated as some pressure above the pressure of the pneumatic balloon in which a predetermined characteristic of the modulation of the granularity pattern occurs, based on a corresponding algorithm that calculates the contribution of the artifact from arterial pulsations acting against the optical sensing system 104, and another artifact.

In some implementations, a blood pressure measurement measurement benchmark is determined (the benchmark) and subsequent blood pressure measurements are estimated based on continuous monitoring of a vital sign. For example, the reading of the blood pressure reference can be obtained using relative pulse amplitudes of a series of pulsations obtained by measuring the dE / dt_Max, or counting the signal exchange as described above, and using an optical detector 240, a plurality of optical sensing regions 244, a CCD sensing array, or a CMOS sensing array. Then the sensor clamping device 102 can be adjusted to a pressure level with a known pulse rate (due to the already mentioned blood pressure measurement) (the reference range), and the pulse rate can be measured continuously and compared to the reference range. Any subsequent measurement of the pulse amplitude that differs from the reference amplitude can be used, with an appropriate algorithm, to quantitatively measure changes in blood pressure relative to the reference. In this embodiment, the primary purpose of the method is the continuous or periodic monitoring of changes in blood pressure in relation to a value benchmark. In some implementations, the blood pressure measurement benchmark can be determined by other standard methods, such as the auscultation method.

In some implementations, a pulse waveform morphology can be determined by measuring the time-varying value of dE / dt. The morphology of the pulse waveform can be represented by the curve of dE / dt versus time in the course of an arterial pulse. Alternatively the time-varying signal exchange rate can be used, or the threshold crossing rate in a digital CCD or CMOS detection system.

In some implementations, such as those shown in figs. 14A, 14B, and 14C, output unit 106 can determine a vital signal by one or more of the techniques described above. For example, output unit 106 can determine an amplitude, value and / or waveform of one or more arterial pulsations in a waveform generator 436. In some implementations, output unit 106 may include a systolic pressure waveform detector to determine a systolic pressure for an individual, based on a given amplitude, value and / or waveform, and a pressure applied to the individual, that can be detected (for example, a pressure detected in an inflatable air balloon by a pressure sensor). In some implementations, output unit 106 may include a diastolic pressure calculator to determine a diastolic pressure for an individual based on a given amplitude, value and / or waveform and a pressure applied to the individual, which can be detected (for example, example, a pressure detected in an inflatable air balloon by a pressure sensor 128). In some implementation, a heart rate calculator 446 can determine a heart rate from an arterial pulse waveform determined from the optical signal or pressures detected in an inflatable air balloon by a 128 pressure sensor. In some implementations, output unit 106 may include a pulse wave time detector 434, which can ensure that each arterial pulse detected by the optical sensing system 104 corresponds to a pulse detected by an inflatable balloon pressure sensor 128 . In some implementations, the pulse wave time detector 434 provides data for waveform generators 436 to ensure that each waveform generator 436 determines a waveform consistent with the pulsations detected by a balloon pressure sensor inflatable tire 128.

In some implementations, as shown in fig. 14C, output unit 106 can determine an amplitude, value and / or waveform of one or more arterial pulsations for each optical sensing region 244 in a series of waveform generators 436. In some implementations, the Output unit 106 may include a waveform comparator 438 to compare the plurality of amplitudes, values, and / or waveforms. The waveform comparator 438 can select the best optical detection regions 244, average the signals from two or more of the optical detection regions, or otherwise compute a single amplitude, value, and / or waveform based on data from the plurality of optical detection regions 244. In some implementation, a heart rate calculator 446 can determine a heart rate from a single waveform from the optical signal waveform comparator 438 or from pressures detected in an inflatable air balloon by a 128 pressure sensor .

Numerous implementations have been described. However, it will be understood that various modifications can be made without departing from the spirit and scope of the invention. Consequently, other implementations are within the scope of the following claims.