Patent Description:
Most of the commercially-available electronic blood pressure measurement devices use the oscillography to measure blood pressures and, for example, use measure data obtained by the single pressurization oscillography or depressurization oscillography to calculate the blood pressure value; however, insufficient samples obtained during the measurement process may cause inaccurate measurement according to oscillography. Conventionally, the oscillography can be implemented by pressurization measurement manner or depressurization measurement manner. The pressurization measurement oscillography is to obtain pulse characteristic signals for further blood pressure analysis during an inflating process, as shown in <FIG>.

According to the single pressurization oscillography, during the process of slowly inflating an air bag by a pump, the pulse characteristic signals (such as amplitude) are captured to obtain the highest value point, which is defined as an average pressure (Am), and the average pressure (Am) of the pulse characteristic signals is then multiplied by clinical statistical parameters which include a threshold parameter Tsys of systolic blood pressure and a threshold parameter Tdia of diastolic blood pressure, to calculate a systolic pressure pulse characteristic signal (Asys) and a diastolic pressure pulse characteristic signal (Adia), respectively, and then the systolic blood pressure (Psys) and diastolic blood pressure (Pdia) can be found based on the two pulse characteristic signals Asys and Adia. The calculation formulas are expressed as follows: <MAT> <MAT>.

The operation of depressurization measurement oscillography is just the opposite of that of the pressurization measurement oscillography. During operation of the depressurization measurement oscillography, quick pressurization is first performed, and the pulse characteristic signals are then measured for further blood pressure analysis during a slow depressurization process, as shown in <FIG>. According to the single depressurization oscillography, the air bag is quickly inflated by the pump, and then the pulse characteristic signals (such as amplitude) are captured to obtain the highest value point, which is defined as an average pressure (Am), during the slow depressurization process, and the average pressure (Am) of the pulse characteristic signal is multiplied by clinical statistical parameters which include the threshold parameter Tsys of systolic pressure and the threshold parameter Tdia of diastolic pressure, to calculate the systolic pressure pulse characteristic signal (Asys) and diastolic pressure pulse characteristic signal (Adia), respectively, and then the systolic pressure (Psys) and diastolic pressure (Pdia) can be found based on the two pulse characteristic signals Asys and Adia. The calculation formulas of single depressurization oscillography are the same as the above formulas (<NUM>) and (<NUM>).

However, during the single pressurization oscillography measurement shown in <FIG>, the measurement for pulse characteristic is stopped when it is determined the systolic pressure (Psys) is captured, and this scheme may terminate measurements for some subjects because of misjudgment for the systolic pressure even if the correct systolic blood pressure is not captured; in the other hand, during the single depressurization oscillography measurement shown in <FIG>, the measurement of the pulse characteristic is stopped when it is determined that the diastolic pressure (Pdia) is captured, but this scheme may terminate the measurement for some subjects because of misjudgment of the diastolic pressure even if the correct diastolic pressure is not captured.

Furthermore, the analysis of atrial fibrillation in the prior art uses the electrocardiogram measurement method, and then uses the heartbeat interval to determine atrial fibrillation. Therefore, conventional electronic blood pressure measurement device cannot determine atrial fibrillation by electrocardiographic measurement. For example, patent application publication <CIT> discloses a blood pressure calculation method having the features of the preamble of claim <NUM>, and also a blood pressure measurement device having the features of the preamble of claim <NUM>. The method for measuring systolic arterial blood pressure of a patient described therein utilizes a finger cuff including an inflatable bladder and a pulsatility sensor that detects arterial pulsatility in a finger of the patient, wherein the method includes steps of inflating the bladder of the finger cuff until the finger cuff applies a first pressure to the finger; deflating the bladder of the finger cuff until the finger cuff applies a second pressure to the finger; monitoring the arterial pulsatility in the finger with the pulsatility sensor; and obtaining a measurement of the systolic arterial blood pressure based on pressure applied to the finger by the finger cuff and the arterial pulsatility in the finger. Patent application publication <CIT> teaches a non-invasive arterial blood pressure monitor using an inflatable cuff that incorporates the first bladder that is filled with non-compressible liquid or gel. From patent specification <CIT> an electronic blood pressure meter is known, wherein pressurization requirement of the cuff is minimized by predicting a systolic blood pressure level from blood vessel information which may be obtained with an initial cuff pressure which is lower than the systolic blood pressure. Patent application publication <CIT> discloses a biological body atrial fibrillation determination device, and an irregular pulse wave IHB is extracted out of multiple pulse waves. Other relevant prior art is disclosed in <CIT>.

Therefore, the present invention is to develop a blood pressure measurement device and a blood pressure calculation method thereof to preclude the measurement inaccuracy caused by the misjudgment of the blood pressure measurement device, and adopt correct measurement data to improve accuracy of the obtained systolic pressure (Psys) and diastolic pressure (Pdia), so as to improve industrially applicability of the blood pressure measurement device.

An objective of the present invention is to prevent a condition that the blood pressure measurement device determines wrong measurement data for extracting pulse characteristic signals, so as to extract correct measurement data to improve the accuracy of measuring a systolic pressure (Psys) and a diastolic pressure (Pdia), thereby providing a blood pressure measurement device and a blood pressure calculation method.

In order to achieve the objective, the present invention provides a blood pressure calculation method having the features of claim <NUM>. Further embodiments are subject-matter of the dependent claims. The blood pressure calculation method is applied to a blood pressure measurement device including a pressurizing motor unit and at least one exhaust valve unit in communication with an airbag unit, and the blood pressure calculation method includes steps of controlling the pressurizing motor unit to pressurize the airbag unit; measuring pressurized measurement data from the airbag unit during a pressurization process; controlling the pressurizing motor unit to stop pressurizing the airbag unit, and then controlling the at least one exhaust valve unit to depressurize the airbag unit; measuring depressurized measurement data from the airbag unit during a depressurization process; extracting at least one blood pressure parameter from each of the pressurized measurement data and the depressurized measurement data; and calculating an average of the blood pressure parameters extracted from the pressurized measurement data and the depressurized measurement data, to obtain a blood pressure measurement result.

According to an embodiment, the blood pressure calculation method further includes steps of extracting maximum amplitude data in pressurized measurement and maximum amplitude data in depressurized measurement from the pressurized measurement data and the depressurized measurement data, respectively; calculating an average of the maximum amplitude data in pressurized measurement and the maximum amplitude data in depressurized measurement; calculating an product of the average and a threshold parameter of the systolic pressure in depressurized measurement, and using the calculated product as an amplitude threshold of the systolic pressure in depressurized measurement; extracting or deducing pressure data from the depressurized measurement data based on the amplitude threshold of the systolic pressure in depressurized measurement, and using the pressure data as a systolic pressure value of the blood pressure measurement result.

According to an embodiment, the blood pressure calculation method further includes steps of extracting maximum amplitude data in pressurized measurement and maximum amplitude data in depressurized measurement; calculating an average of the maximum amplitude data in pressurized measurement and the maximum amplitude data in depressurized measurement; calculating an product of the average and a threshold parameter of the diastolic pressure in pressurized measurement, and using the calculated product as an amplitude threshold of the diastolic pressure in pressurized measurement; extracting or deducing pressure data from the pressurized measurement data based on the amplitude threshold of the diastolic pressure in pressurized measurement, and using the pressure data as a diastolic pressure value of the blood pressure measurement result.

In order to achieve the objective, the present invention further provides a blood pressure measurement device having the features of claim <NUM>. Further embodiments are subject-matter of the dependent claims. The blood pressure measurement device includes an airbag unit, a pressurizing motor unit, at least one exhaust valve unit, a sensing unit, a display unit, a memory and a processing unit. The pressurizing motor unit is in communication with the airbag unit. The at least one exhaust valve unit is in communication with the airbag unit. The sensing unit is configured to obtain measurement data from the airbag unit. The display unit is configured to display a blood pressure measurement result. The memory is configured to store a program instruction set. The processing unit is configured to execute the program instruction set to control the pressurizing motor unit to pressurize the airbag unit; receive pressurized measurement data from the sensing unit during a pressurization process; control the pressurizing motor unit to stop pressurizing the airbag unit, and then control the exhaust valve unit to depressurize the airbag unit; receive depressurized measurement data from the sensing unit during a depressurization process; extracting at least one blood pressure parameter from each of the pressurized measurement data and the depressurized measurement data; calculate an average of the blood pressure parameters extracted from the pressurized measurement data and the depressurized measurement data, to obtain a blood pressure measurement result.

According to an embodiment, the processing unit of the blood pressure measurement device is configured to execute the program instruction set to: extract maximum amplitude data in pressurized measurement and maximum amplitude data in depressurized measurement from the pressurized measurement data and the depressurized measurement data, respectively; calculate an average of the maximum amplitude data in pressurized measurement and the maximum amplitude data in depressurized measurement; calculate an product of the average and a threshold parameter of the systolic pressure in depressurized measurement, and use the calculated product as an amplitude threshold of the systolic pressure in depressurized measurement; extract or deduce pressure data from the depressurized measurement data based on the amplitude threshold of the systolic pressure in depressurized measurement, and use the pressure data as a systolic pressure value of the blood pressure measurement result.

According to an embodiment, the processing unit of the blood pressure measurement device further executes the program instruction set to: extract maximum amplitude data in pressurized measurement and maximum amplitude data in depressurized measurement from the pressurized measurement data and the depressurized measurement data, respectively; calculate an average of the maximum amplitude data in pressurized measurement and the maximum amplitude data in depressurized measurement; calculate an product of the average and a threshold parameter of the diastolic pressure in pressurized measurement, and use the calculated product as an amplitude threshold of the diastolic pressure in pressurized measurement; extract or deduce pressure data from the pressurized measurement data based on the amplitude threshold of the diastolic pressure in pressurized measurement, and use the pressure data as a diastolic pressure value of the blood pressure measurement result.

According to the blood pressure measurement device and the blood pressure calculation method of the present disclosure, during the single cycle of pressurization and depressurization, the pressurized measurement data and depressurized measurement data are extracted, respectively, and the correct measurement data can be extracted from the pressurized measurement data and depressurized measurement data, so that the accuracy of obtaining systolic pressure (Psys) and the diastolic pressure (Pdia) can be improved.

The structure, operating principle and effects of the blood pressure method and apparatus will be described in detail by way of various embodiments which are illustrated in the accompanying drawings.

The following embodiments are herein described in detail with reference to the accompanying drawings. These drawings show specific examples of the embodiments. It is to be acknowledged that these embodiments are exemplary implementations and are not to be construed as limiting the scope of the present invention, which is defined by the claims. Further modifications to the disclosed embodiments, as well as other embodiments, are possible. These embodiments are provided so that this disclosure is thorough and complete, and fully conveys the inventive concept to those skilled in the art. Regarding the drawings, the relative proportions and ratios of elements in the drawings may be exaggerated or diminished in size for the sake of clarity and convenience. Such arbitrary proportions are only illustrative and not limiting in any way. The same reference numbers are used in the drawings and description to refer to the same or like parts.

It is to be acknowledged that, although the terms 'first', 'second', 'third', and so on, may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only for the purpose of distinguishing one component from another component. Thus, a first element discussed herein could be termed a second element without altering the description of the present disclosure. As used herein, the term "or" includes any and all combinations of one or more of the associated listed items.

It will be acknowledged that when an element or layer is referred to as being "on," "connected to" or "coupled to" another element or layer, it can be directly on, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers present.

In addition, unless explicitly described to the contrary, the word "comprise" and variations such as "comprises" or "comprising", will be acknowledged to imply the inclusion of stated elements but not the exclusion of any other elements.

Please refer to <FIG>, which shows a functional block diagram of a blood pressure measurement device. In an embodiment, a blood pressure measurement device <NUM> includes a micro-processor unit <NUM>, a display output unit <NUM>, a button unit <NUM>, a memory <NUM>, a pressurizing motor unit <NUM>, a pressure sensing unit <NUM>, a slow exhaust valve unit <NUM>, a quick exhaust valve unit <NUM>, an airbag unit <NUM> and a power supply unit. The power supply unit is not shown in <FIG> and configured to provide electrical power for the units of the blood pressure measurement device <NUM>. In an embodiment, the airbag unit <NUM> can be a cuff airbag unit, and the display output unit <NUM> can be a liquid crystal display (LCD) device. The pressurizing motor unit <NUM>, the slow exhaust valve unit <NUM>, and the quick exhaust valve unit <NUM> are in communication with the airbag unit <NUM>. The micro-processor unit <NUM> can control the pressurizing motor unit <NUM>, the slow exhaust valve unit <NUM> and the quick exhaust valve unit <NUM>, to perform pressurization and depressurization of the airbag unit <NUM>, and the pressure sensing unit <NUM> can sense the airbag unit <NUM> and the micro-processor unit <NUM> obtains measurement data from the pressure sensing unit <NUM>.

In an embodiment, a user can operate the button unit <NUM> to trigger the micro-processor unit <NUM> to execute the program instruction set stored in the memory <NUM>; in an embodiment, the memory <NUM> can be embedded in the micro-processor unit <NUM>, and the micro-processor unit <NUM> can execute the program instruction set to implement steps <NUM> to <NUM> of a blood pressure calculation method <NUM> shown in <FIG>.

Please refer to <FIG>, which shows a flowchart of a blood pressure calculation method. The blood pressure calculation method <NUM> includes steps <NUM> to <NUM>. In a step <NUM>, the micro-processor unit <NUM> executes the program instruction set to detect the operation of the user on the button unit <NUM>, and then enable the quick exhaust valve unit <NUM> to quickly exhaust the airbag unit <NUM>. In a step <NUM>, the micro-processor unit <NUM> executes the program instruction set to read a pressure value of the airbag unit <NUM> from the pressure sensing unit <NUM>. In a step <NUM>, the micro-processor unit <NUM> continuously executes the program instruction set until the quick exhaust valve unit <NUM> decreases the pressure value of the airbag unit <NUM> to zero, and the micro-processor unit <NUM> then turns off the quick exhaust valve unit <NUM> and enables the pressurizing motor unit <NUM> to perform slow pressurization and inflation on the airbag unit <NUM>.

Please refer to <FIG>, which shows a schematic view of pulse signals and pressure values measured in single cycle of pressurization and depressurization of the blood pressure calculation method. In a step <NUM>, during the pressurized measurement process <NUM>, the micro-processor unit <NUM> executes the program instruction set to obtain pressurized measurement data from the airbag unit <NUM> through the pressure sensing unit <NUM>, and the pressurized measurement data can include amplitude data of a sequence of pulse signals, corresponding pressure data, and pulse interval data measured during the pressurized measurement process <NUM> shown in <FIG>. In a step <NUM>, the micro-processor unit <NUM> executes the program instruction set to determine the pressurization stop timing based on the pressurized measurement data, and then turn off the pressurizing motor unit <NUM> to stop pressurizing the airbag unit <NUM> and enable the slow exhaust valve unit <NUM> to slowly exhaust the airbag unit <NUM> according to the pressurization stop timing. In an embodiment, the pressurization stop timing can be the time when the amplitude of the extracted pulse is too small or no pulse signal can be extracted.

In a step <NUM>, during the depressurized measurement process <NUM>, the micro-processor unit <NUM> executes the program instruction set to obtain depressurized measurement data from the airbag unit <NUM> through the pressure sensing unit <NUM>, and the depressurized measurement data can include the amplitude data of a sequence of pulse signals, the corresponding pressure data, and pulse interval data measured during the depressurized measurement process <NUM> shown in <FIG>. In a step <NUM>, the micro-processor unit <NUM> executes the program instruction set to determine the measurement end timing based on the depressurized measurement data, and then enable the quick exhaust valve unit <NUM> to quickly exhaust the airbag unit <NUM>. In an embodiment, the measurement stop timing can be the time when the amplitude of the extracted pulse is too small or no pulse signal can be extracted. In a step <NUM>, the calculation is performed based on the depressurized measurement data and pressurized measurement data to obtain a blood pressure measurement result, and a systolic pressure (Psys) and a diastolic pressure (Pdia) are displayed on the display output unit <NUM>.

In the step <NUM> of the calculation method, the micro-processor unit <NUM> can further execute the program instruction set to extract the at least one blood pressure parameter from each of the pressurized measurement data and the depressurized measurement data; in different embodiment of the present invention, the blood pressure parameter can include maximum amplitude data Am1 in pressurized measurement and maximum amplitude data Am2 in depressurized measurement, or a diastolic pressure value Pdia1 in pressurized measurement and a diastolic pressure value Pdia2 in depressurized measurement, or a systolic pressure value Psys1 in pressurized measurement and a systolic pressure value Psys2 in depressurized measurement. Next, the micro-processor unit <NUM> can further execute the program instruction set to perform calculation to obtain an average of the blood pressure parameters extracted from the pressurized measurement data and the depressurized measurement data; for example, the average can be, an average Am of the maximum amplitude data Am1 in pressurized measurement and the maximum amplitude data Am2 in depressurized measurement, as shown the following equation (<NUM>), to obtain a blood pressure measurement result.

In the step <NUM> of the blood pressure calculation method, the micro-processor unit <NUM> can further execute the program instruction set to calculate an product of the average Am and a threshold parameter Tdia1 of the diastolic pressure in pressurized measurement and use the calculated product as an amplitude threshold Adia of the diastolic pressure in pressurized measurement, and the micro-processor unit <NUM> further executes the program instruction set to calculate an product of the average Am and a threshold parameter Tsys2 of the systolic pressure in depressurized measurement, and use the calculated product as an amplitude threshold Asys of the systolic pressure in depressurized measurement, and then extract or deduce pressure values from the pressurized measurement data and the depressurized measurement data based on the amplitude threshold Adia of the diastolic pressure in pressurized measurement and the amplitude threshold Asys of the systolic pressure in depressurized measurement, respectively, and use the pressure values as the diastolic pressure value Pdia and the systolic pressure value Psys of the blood pressure measurement result. The systolic pressure Psys and the diastolic pressure Pdia are displayed on the display output unit <NUM>. In an embodiment, the threshold parameter Tdia1 of the diastolic pressure in pressurized measurement and the threshold parameter Tsys2 of the systolic pressure in depressurized measurement can be threshold values obtained from statistics of the clinical experimental results. <MAT> <MAT> <MAT>.

Please refer to <FIG>, which shows a measurement data table obtained in single cycle of pressurization and depressurization of the blood pressure calculation method. In an embodiment, the blood pressure measurement device can perform single cycle of pressurization and depressurization of the blood pressure calculation method to obtain amplitude data of a sequence of pulse signals and corresponding pressure data. The measurement data table shown in <FIG> includes the pressurized measurement data measured from the airbag unit <NUM> in pressurized measurement process <NUM>, and the depressurized measurement data measured from the airbag unit <NUM> in depressurized measurement process <NUM>.

In an embodiment, according to statistics of clinical experimental results, the threshold parameter Tdia1 of the diastolic pressure in pressurized measurement is <NUM>, and the threshold parameter Tsys2 of the systolic pressure in depressurized measurement is <NUM>. In the step <NUM> of the blood pressure calculation method, the maximum amplitude data Am <NUM> (Am1=<NUM>) in pressurized measurement and the maximum amplitude data Am2 (Am2=<NUM>) in depressurized measurement are extracted from the sequence of the amplitude data of the pulse signals of the pressurized measurement data and the depressurized measurement data, respectively. The average Am of the maximum amplitude data Am1 in pressurized measurement and the maximum amplitude data Am2 in depressurized measurement is calculated to be <NUM>. According to the equations (<NUM>) and (<NUM>), the amplitude threshold Adia of the diastolic pressure in pressurized measurement and the amplitude threshold Asys of the systolic pressure in depressurized measurement are calculated to be <NUM> and <NUM>, respectively. Next, based on the amplitude threshold Adia (Adia =<NUM>) of the diastolic pressure in pressurized measurement, the search is performed in the sequence of the amplitude data of the pulse signal in the pressurized measurement data from the location where the maximum amplitude data Am1 in pressurized measurement is equal to <NUM>, in the decreasing direction of the pressure value, such as the direction from Am1 to Adia1 shown in <FIG>, to find the amplitude threshold Adia (Adia=<NUM>) of the diastolic pressure in pressurized measurement. After the amplitude threshold Adia with value of <NUM> is found, the pressure data, with value of <NUM>, corresponding to amplitude threshold Adia, with value of <NUM>, of the diastolic pressure in pressurized measurement can be extracted, and the pressure data with value of <NUM> is used as the diastolic pressure value Pdia, with value of <NUM>, of the blood pressure measurement result.

Next, based on the amplitude threshold Adia, which is set as <NUM>, of the diastolic pressure in pressurized measurement, the search is performed in the sequence of the amplitude data of the pulse signal in the depressurized measurement data from the maximum amplitude data Am2 (Am2 =<NUM>) in depressurized measurement in an increasing direction of the pressure value, such as the direction from Am2 to Asys2 shown in <FIG>, to find the amplitude threshold Asys, with a value of <NUM>, of the systolic pressure in depressurized measurement. After the amplitude threshold Adia with the value of <NUM> is found, the pressure data with a value of115 and corresponding to amplitude threshold Asys (Asys =<NUM>) of the systolic pressure in depressurized measurement can be extracted and used as the systolic pressure value Psys, with the value of <NUM>, of the blood pressure measurement result. Next, the systolic pressure value Psys with the value of <NUM> mmHg and the diastolic pressure value Pdia with the value of <NUM> mmHg are displayed on the display output unit <NUM>.

Furthermore, during the process of searching the amplitude threshold Adia (Adia=<NUM>) of the diastolic pressure in pressurized measurement and the amplitude threshold Asys (Asys=<NUM>) of the systolic pressure in depressurized measurement from a sequence of the amplitude data of the pulse signal based on the calculation result, it is possible that there is no value directly corresponding to Adia or Asys in the sequence of measured amplitude data; therefore, in an embodiment, two amplitude values approximate to each of Adia and Asys, and the corresponding pressure values can be found first, and the interpolation method can be performed on the two approximate amplitude values to deduce a pressure value corresponding to each of Adia and Asys based on a slope between the two approximate amplitude values, and the deduced pressure values can be used as the diastolic pressure value and the systolic pressure value of the blood pressure measurement result.

The present disclosure further provides an accuracy comparison between the blood pressure calculation method of the present disclosure and the conventional single-pressurization oscillography shown in <FIG> and the conventional single- depressurization oscillography shown in <FIG>. The clinical test measures blood pressures of <NUM> people by using mercury auscultation as a standard manner, and each person measures <NUM> times, and a total of <NUM> pieces of comparison data are obtained. The pieces of data measure by the blood pressure calculation method of the present disclosure and by the conventional single-pressurization oscillography shown in <FIG> and the conventional single- depressurization oscillography shown in <FIG> are compared with the measurement results of the mercury blood pressure measurement device to score errors, the error within <NUM> mmHg is scored with <NUM>, the error within mmHg is scored with <NUM>, the error exceeding <NUM> mmHg is scored with <NUM>, and full score is <NUM> (<NUM>%). The statistics result is shown in the table below.

According to the comparison of the statistics results, the average score of the measured systolic pressure (Psys) and the diastolic pressure (Pdia) of the blood pressure calculation method of the present disclosure is higher than that of the conventional single-pressurization oscillography and the single-depressurization oscillography Furthermore, according to the statistics result, it is obvious that the blood pressure calculation method of the present disclosure can improve the accuracy of the obtained systolic pressure (Psys) and the diastolic pressure (Pdia) because of precluding the data of systolic pressure (Psys) obtained in pressurized measurement and collecting correct depressurized measurement data to obtain systolic pressure (Psys), and precluding the data of the diastolic pressure (Pdia) obtained in depressurized measurement and collecting correct pressurized measurement data to obtain diastolic pressure (Pdia).

In an embodiment, the depressurized measurement data is used to obtain data of the systolic pressure (Psys) only, so in the step <NUM> of the blood pressure calculation method of the present invention, the measurement stop timing can be set as the time after the values of the maximum amplitude data Am2 in depressurized measurement and corresponding pressure are captured, and the quick exhaust valve unit <NUM> can then be enabled to complete the measurement. Furthermore, the micro-processor unit <NUM> can execute the program instruction set to further determine atrial fibrillation based on pulse interval data of the pressurized measurement data and the depressurized measurement data obtained in single pressurization process and depressurization process.

The atrial fibrillation determination method of the present disclosure includes flows (A) to (C) described below.

The coefficient of variation (CV) value is generally used to estimate the degree of data dispersion. The coefficient of variation of a set of data is defined as the percentage expression of the standard deviation (SD) of the set of data divided by the mean (M) of the set of data, and the standard deviation formula is expressed as follows:.

Where X is a sequence of data (such as interval of blood pressure pulse signals), N is the number of data samples, and M is the mean value of the data samples; as known from the above formula, when the number (N) of the sample data is more, the SD becomes more stable; in contrast, when the number (N) of sample data is less, the SD becomes more unstable; therefore, the standard deviation SD is more suitable as a statistical factor for long-term monitoring data. For short-term monitoring, RMSSD can be used for evaluation, and the formula is expressed as follows:
<MAT>.

The ratio of RMSSD to mean (M) can be used to estimate the degree of short-term data dispersion.

Shannon entropy (ShEn) is a parameter statistic value used to measure the uncertainty of random variables. ShEn is related to the complexity of the data set and the ability of the data set to predict future data pointing from past data points. ShEn is one of the parameter tests in the AF calculation method of the present invention. Therefore, similar to RMSSD, ShEn is highly sensitive to abnormal value, and ShEn is between <NUM> and <NUM> (including <NUM> and <NUM>) for any data set. A fully predictable single constant value has a ShEn value of zero. Completely random data (such as white noise) has ShEn close to <NUM>. It is assumed here that atrial fibrillation is associated with higher uncertainty, so ShEn value of atrial fibrillation is higher than that of normal sinus rhythm. The formula is expressed as follows:
<MAT>.

Turning point ratio (TPR) is a non-parametric statistic used to measure the randomness of fluctuations in a data set. It is the only non-parametric test used in the AF calculation method of the present disclosure, so unlike ShEn and RMSSD, TPR is not affected by hypothesis about the distribution of the data set. The turning point is a point with a value higher than that of the previous and next one, or lower than that of the previous and next one. TPR is calculated by comparing the number of turning points in the data set with the maximum number of possible turning points. The turning point ratio calculation assumes that the data is stationary, especially the fluctuation is random and not faster or less frequent than explained by chance alone; in this case, the data contains trends. The statistical test used in the algorithm uses the null hypothesis H0 in which the sequence is stationary, and the other hypothesis H1 in which the sequence is non-stationary. More specifically, the null hypothesis is that the pulse interval is random and therefore corresponds to AF; the alternative hypothesis is that the pulse interval is non-random and corresponds to normal sinus rhythm. Any random data, such as white noise, is expected to have a turning point about every <NUM> data points.

The extracted pulse signal is converted into a frequency spectrum by Fourier transform, and then clutter can be obtained based on statistics of peak points of the spectrum.

(C) Estimation flow for determining whether atrial fibrillation exists according to collection of clinical data and the found best determination criteria.

Claim 1:
A blood pressure calculation method applied to a blood pressure measurement device comprising a pressurizing motor unit (<NUM>) and at least one exhaust valve unit (<NUM>,<NUM>) in communication with an airbag unit (<NUM>), and the blood pressure calculation method comprising:
controlling the pressurizing motor unit (<NUM>) to pressurize the airbag unit (<NUM>);
measuring pressurized measurement data from the airbag unit (<NUM>) during a pressurization process;
controlling the pressurizing motor unit (<NUM>) to stop pressurizing the airbag unit (<NUM>), and then controlling the at least one exhaust valve unit (<NUM>,<NUM>) to depressurize the airbag unit (<NUM>);
measuring depressurized measurement data from the airbag unit (<NUM>) during a depressurization process;
characterised in that
the pressurized measurement data and the depressurized measurement data are processed to extract or deduce a systolic pressure value and a diastolic pressure value of a blood pressure measurement result;,
thus extracting at least one blood pressure parameter from each of the pressurized measurement data and the depressurized measurement data, wherein the blood pressure parameter comprises amplitude data of a sequence of pulse signals and pressure data corresponding to the amplitude data; and
wherein the blood pressure calculation method further comprises
extracting maximum amplitude data in pressurized measurement and maximum amplitude data in depressurized measurement from the pressurized measurement data and the depressurized measurement data, respectively;
calculating an average of the maximum amplitude data in pressurized measurement and the maximum amplitude data in depressurized measurement;
calculating a product of the average and a threshold parameter of the systolic pressure in depressurized measurement, and using the calculated production as an amplitude threshold of systolic pressure in depressurized measurement; and
extracting or deducing pressure data from the depressurized measurement data based on the amplitude threshold of systolic pressure in depressurized measurement, and using the pressure data as the systolic pressure value of the blood pressure measurement result.