Method for calculating hypoxia burden based on polysomnogram

Abstract

The invention provides a method for calculating hypoxia burden based on a polysomnogram, and the method comprises the steps: reading monitoring data from the polysomnogram, and carrying out the abnormal value processing of the monitoring data; blood oxygen data of a period of time before and after the end of each respiratory event are extracted, curve superposition is carried out, and a superposition curve is obtained through smoothing; according to the rule of blood oxygen change in sleep apnea, the wave trough of the superposition curve is detected within the limited range, then the wave crests on the two sides are detected, and the wave crest-wave trough-wave crest range is set as the oxygen deficit range; summing the area of the blood oxygen curve under the blood oxygen baseline in the oxygen deficit range corresponding to each breathing event; and removing the repeatedly calculated area, and carrying out standardization processing on the summed area under the curve, so that the hypoxia burden caused by the respiratory event is accurately calculated and obtained. According to the invention, the hypoxia condition caused by the respiratory event can be accurately calculated.

Description

Technical Field

[0001] The present invention relates to the technical field of sleep breathing research, and in particular to a method for calculating hypoxia burden based on polysomnography. Background Art

[0002] Obstructive Sleep Apnea Hypopnea Syndrome (OSAHS) is a widespread and sleep-related breathing disorder. Its main feature is the repeated collapse of the pharyngeal upper airway, which is manifested as repeated apnea and hypopnea during sleep, accompanied by severe snoring at night and daytime sleepiness. OSAHS is not only a risk factor for a variety of chronic diseases such as cardiovascular disease and hypertension, but also an important cause of some acute diseases such as stroke, myocardial infarction, cor pulmonale, congestive heart failure, and even sudden death. If it is not treated effectively in time, it will pose a serious threat to personal health, leading to a decline in the patient's quality of life, impaired work and study performance, and even an increased risk of traffic accidents.

[0003] The diagnosis of OSAHS is mainly based on the calculation of the Apnea Hypopnea Index (AHI), which is used to measure the frequency of reduced airflow associated with upper airway collapse or stenosis. OSAHS can be diagnosed when the AHI is ≥5 events / hour in adults and ≥1 event / hour in children.

[0004] The middle-aged and elderly are the most susceptible population for OSAHS. The number of patients with sleep apnea in my country has exceeded 100 million, of which more than 65 million are moderate to severe patients. A common feature of OSAHS patients is the combination of other systemic diseases, such as hypertension and chronic obstructive pneumonia. Therefore, when OSAHS patients sleep at night, they often experience a decrease in blood oxygen induced by respiratory events. Under the influence of other systemic diseases, they cannot return to the initial baseline level for a considerable period of time after the respiratory event ends. Therefore, the previous method of selecting the desaturated part of blood oxygen by the characteristics of the blood oxygen saturation waveform has two major defects: first, in the population of OSAHS patients with other systemic diseases, the blood oxygen decline waveform is variable due to the influence of other systemic diseases, resulting in inconsistent blood oxygen saturation waveform characteristics and partial misidentification of blood oxygen desaturation; second, by calculating the entire blood oxygen curve, the blood oxygen decline affected by other systemic diseases will be included, resulting in miscalculation of the blood oxygen decline caused by OSAHS respiratory events, which will cause great errors and fail to correctly assess OSAHS-related hypoxia. Summary of the invention

[0005] In view of the defects in the prior art, the purpose of the present invention is to provide a method for calculating the hypoxia burden based on polysomnography, which can accurately calculate the hypoxia caused by respiratory events.

[0006] To solve the above problems, the technical solution of the present invention is:

[0007] A method for calculating hypoxia burden based on polysomnography comprises the following steps:

[0008] Read monitoring data from polysomnography and process abnormal values ​​of the monitoring data;

[0009] The blood oxygen data of a period of time before and after each respiratory event is extracted, and the curves are superimposed and smoothed to obtain a superimposed curve;

[0010] According to the law of blood oxygen changes during sleep apnea, the trough of the superimposed curve is detected within a limited range, and then the peaks on both sides are detected, and the peak-trough-peak range is set as the hypoxia range;

[0011] The areas of the blood oxygen curve below the blood oxygen level within the hypoxic range corresponding to each respiratory event are summed;

[0012] The duplicated areas were removed and the summed area under the curve was standardized to accurately calculate the hypoxia burden caused by respiratory events.

[0013] Preferably, in the step of reading the monitoring data from the polysomnogram and performing abnormal value processing on the monitoring data, the abnormal value is processed in a manner of removing the abnormal data and not involving it in subsequent calculations.

[0014] Preferably, the step of extracting the blood oxygen data for a period of time before and after the end of each respiratory event, and superimposing and smoothing the curves to obtain the superimposed curve specifically includes: setting the end point of the respiratory event as point 0, taking the start point of the respiratory event as the starting point, and taking the end point of the next respiratory event as the end point, selecting the blood oxygen curve corresponding to each respiratory event, aligning, overlapping, and smoothing each blood oxygen curve at point 0 to obtain the superimposed curve.

[0015] Preferably, the blood oxygen statistical value for a period of time before the zero point of each respiratory event is used as the blood oxygen baseline of the event, and the statistical value can be set as a maximum value, an average value or a quartile value.

[0016] Preferably, the step of detecting the trough of the superimposed curve within a limited range according to the law of blood oxygen change in sleep apnea, and then detecting the peaks on both sides, and setting the peak-trough-peak range as the hypoxia range specifically includes: for the superimposed curve, finding the time point where the minimum value is located in the range of 0 to 20 seconds as the trough, finding the first maximum value points on both sides of the trough point as the peak points, and the time area between the two peak points is called the hypoxia calculation range.

[0017] Preferably, the step of summing the areas of the blood oxygen curve below the blood oxygen level within the hypoxia range corresponding to each respiratory event specifically includes: calculating, for the blood oxygen curve corresponding to each respiratory event, the area under the curve enclosed by the blood oxygen level when the blood oxygen curve within the hypoxia range is below the blood oxygen level, and summing the areas under the curve for each respiratory event.

[0018] Preferably, in the step of removing the repeatedly calculated area and normalizing the summed area under the curve to accurately calculate the hypoxia burden caused by the respiratory event, during the calculation, it is detected whether the calculated areas of the two respiratory events overlap. If overlap occurs, when calculating the area under the blood oxygen desaturation curve, the repeatedly calculated part in the hypoxia range of the first respiratory event is deleted.

[0019] Preferably, in the step of removing the repeatedly calculated areas and standardizing the summed area under the curve to accurately calculate the hypoxia burden caused by respiratory events, the standardization includes: the unit of the summed area under the curve is %*seconds, the unit of the total monitoring time is hours, the standardized area = (area under the curve / 60) / total monitoring time, and the unit of the standardized area is %*minutes / hours.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The method of the present invention can obtain the personalized blood oxygen calculation range of each patient by superimposing the oxygen saturation curve of each patient, thereby realizing personalized medical treatment;

[0022] 2. The method of the present invention significantly improves the accuracy of blood oxygen desaturation curve analysis by extracting, standardizing, and overlapping the blood oxygen desaturation curves corresponding to respiratory events, thereby accurately distinguishing blood oxygen curves related to respiratory events and those related to diseases, and reducing the errors existing in traditional methods;

[0023] 3. The method of the present invention enhances the repeatability and consistency of the calculation by optimizing the blood oxygen curve fitting calculation process, which is particularly important for patients with frequent respiratory events. It solves the problems of difficult peak positioning and repeated area calculation that may be encountered in the operation and analysis process of traditional technologies, making the diagnosis and treatment process more accurate and reliable.

[0024] 4. The present invention improves the accuracy of calculating the degree of individual hypoxia by improving the hypoxia burden calculation method, reduces the additional treatment costs caused by misdiagnosis, improves the efficiency of the use of medical resources, and generates economic benefits for both hospitals and patients;

[0025] 5. By providing a more accurate calculation of hypoxia burden, the present invention can achieve early detection, early diagnosis and early treatment of hypoxia caused by diseases such as OSAHS, reduce the health risks caused by the disease, and thus improve the overall health level of the public. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0027] Figure 1 A flowchart of a method for calculating hypoxia burden based on polysomnography according to the present invention;

[0028] Figure 2 A detailed flow chart of the method for calculating hypoxia burden based on polysomnography of the present invention;

[0029] Figure 3A and Figure 3B Schematic diagram for calculating the hypoxia range;

[0030] Figure 4 This is a schematic diagram of calculating the area under the blood oxygen desaturation curve according to the present invention. DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0032] Specifically, the present invention provides a method for calculating hypoxia burden based on polysomnography, such as Figure 1 and Figure 2 As shown, the method comprises the following steps:

[0033] S1: read monitoring data from the polysomnogram and process abnormal values ​​of the monitoring data;

[0034] Specifically, the monitoring data is read from the polysomnography (PSG) and the abnormal value processing is performed on the read monitoring data. PSG is the patient's sleep monitoring data for the whole night. During the monitoring process, it is inevitable that abnormal values ​​will be generated due to technical or other reasons, such as sensor abnormalities generating data artifacts, patients taking off the sensor when going to the toilet, etc. Before subsequent analysis, the abnormal values ​​need to be processed. The specific processing method is to remove the abnormal data and not participate in subsequent calculations.

[0035] In this embodiment, the abnormal value processing includes two points: 1. Selecting the blood oxygen curve during sleep for calculation 2. Selecting to remove the blood oxygen artifacts. Because the characteristic of sleep obstructive apnea syndrome OSAHS is that the patient almost does not have sleep obstruction or pause during the day, when sleeping at night, sleep obstruction or pause will occur, so the night non-sleep period data should be removed.

[0036] S2: extract the blood oxygen data for a period of time before and after each respiratory event, and perform curve superposition and smoothing to obtain a superimposed curve;

[0037] Specifically, the end point of the respiratory event is set as point 0, the start point of the respiratory event is taken as the starting point, and the end point of the next respiratory event is taken as the end point, and the blood oxygen curve corresponding to each respiratory event is selected; each segment of the blood oxygen curve is aligned, overlapped, and smoothed at point 0 to obtain a superimposed curve.

[0038] Respiratory events (i.e., hypopnea and apnea) that occur during sleep may occur in a connected manner, especially in patients with severe OSAHS, such as middle-aged and elderly patients. Each respiratory event is close to each other, resulting in a continuous peak-trough pattern on the blood oxygen curve. The drop in blood oxygen caused by the previous respiratory event has not yet fully recovered, and the next respiratory event has begun. At this time, if the range of the blood oxygen curve corresponding to the respiratory event is not limited, when obtaining overlapping curves, it will result in multiple peaks and troughs of overlapping curves, such as Figure 3A As shown in the figure, the definition of hypoxia range is inconsistent, and the inconsistent definition of hypoxia range will seriously affect the calculation results, such as Figure 3B However, the method of the present invention greatly avoids the appearance of "pseudo peaks" by limiting the range of the blood oxygen curve after the respiratory event (ie, taking the end point of the next respiratory event as the end point).

[0039] The blood oxygen statistical value of a period of time before the 0 point of each respiratory event is used as the blood oxygen baseline of the event. The statistical value can be set to a maximum value, an average value or a quartile value. In this embodiment, the statistical value will be based on the AASM manual, and the maximum value of the blood oxygen in the previous 120 seconds is set as the baseline by default.

[0040] S3: According to the law of blood oxygen changes during sleep apnea, the trough of the superimposed curve is detected within a limited range, and then the peaks on both sides are detected, and the peak-trough-peak range is set as the hypoxia range;

[0041] According to the law of blood oxygen changes during sleep apnea, the trough of the superimposed curve is detected within a limited range, and then the peaks on both sides are detected, and the peak-trough-peak range is set as the hypoxia range, that is, the personalized hypoxia range;

[0042] Specifically, for the superimposed curve, the time point of the minimum value in the range of 0 to 20 seconds is found as the valley bottom, and the first maximum value point on both sides of the valley bottom point is found as the peak point. The time region between the two peak points is called the hypoxia calculation range. Each patient will follow the above process and overlap and fit according to the blood oxygen conditions throughout the night to obtain a personalized hypoxia range, that is, the calculation range of blood oxygen drop related to respiratory events.

[0043] S4: summing the areas of the blood oxygen curve below the blood oxygen level within the hypoxic range corresponding to each respiratory event;

[0044] Specifically, for the blood oxygen curve corresponding to each respiratory event, the area under the curve formed by the blood oxygen level when the blood oxygen curve is below the blood oxygen level in the hypoxia range is calculated, and the area under the curve of each respiratory event is summed.

[0045] S5: Remove the repeatedly calculated areas and standardize the summed area under the curve to accurately calculate the hypoxia burden caused by respiratory events.

[0046] During calculation, if the blood oxygen areas of two adjacent respiratory events overlap, the overlapping parts are removed. Figure 4 The figure shows two consecutive respiratory events in a patient. The curves related to each respiratory event are proposed and aligned on the same objective time axis. As mentioned above, the end time of each respiratory event is 0, and the two curves will be aligned at 0 to obtain the fitting curve and calculate the "hypoxia range". When the hypoxia range is put back into each respiratory event to calculate the blood oxygen desaturation area, it is as follows Figure 4 As shown in Figure 2, the hypoxic range overlapped due to the close proximity of the two respiratory events ( Figure 4 Therefore, when calculating the area under the blood oxygen desaturation curve, the repeated calculated part in the hypoxia range of the first respiratory event is deleted.

[0047] The summed area under the curve is standardized. Since each patient has a different sleep duration, in order to make the indicators comparable, they need to be standardized according to the sleep duration. The unit of the summed area under the curve is %*seconds, and the unit of total sleep duration is hours. The standardized area = (area under the curve / 60) / total sleep duration, and the unit of the standardized area is %*minutes / hour. By standardizing the summed area under the curve, the hypoxia burden caused by respiratory events can be accurately calculated.

[0048] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A method for calculating hypoxia burden based on polysomnography, characterized in that: The method comprises the following steps: Read monitoring data from polysomnography and process abnormal values ​​of the monitoring data; The blood oxygen data of a period of time before and after each respiratory event is extracted, and the curves are superimposed and smoothed to obtain a superimposed curve; According to the law of blood oxygen changes during sleep apnea, the trough of the superimposed curve is detected within a limited range, and then the peaks on both sides are detected, and the peak-trough-peak range is set as the hypoxia range; The areas of the blood oxygen curve below the blood oxygen level within the hypoxic range corresponding to each respiratory event are summed; The duplicated areas were removed and the summed area under the curve was standardized to accurately calculate the hypoxia burden caused by respiratory events.

2. The method for calculating hypoxia burden based on polysomnography according to claim 1, characterized in that: In the step of reading monitoring data from the polysomnogram and performing abnormal value processing on the monitoring data, the abnormal value is processed in a manner of removing the abnormal data and not participating in subsequent calculations.

3. The method for calculating hypoxia burden based on polysomnography according to claim 1, characterized in that: The step of extracting the blood oxygen data for a period of time before and after the end of each respiratory event, and superimposing and smoothing the curves to obtain the superimposed curve specifically includes: setting the end point of the respiratory event as point 0, taking the start point of the respiratory event as the starting point, and taking the end point of the next respiratory event as the end point, selecting the blood oxygen curve corresponding to each respiratory event, and aligning, overlapping, and smoothing each blood oxygen curve at point 0 to obtain the superimposed curve.

4. The method for calculating hypoxia burden based on polysomnography according to claim 3, characterized in that: The blood oxygen statistical value for a period of time before the zero point of each respiratory event is used as the blood oxygen baseline of the event. The statistical value can be set as a maximum value, an average value or a quartile value.

5. The method for calculating hypoxia burden based on polysomnography according to claim 1, characterized in that: The step of detecting the trough of the superimposed curve within a limited range according to the law of blood oxygen change in sleep apnea, and then detecting the peaks on both sides, and setting the peak-trough-peak range as the hypoxia range specifically includes: for the superimposed curve, finding the time point where the minimum value is located in the range of 0 to 20 seconds as the trough, finding the first maximum value points on both sides of the trough point as the peak points, and the time area between the two peak points is called the hypoxia calculation range.

6. The method for calculating hypoxia burden based on polysomnography according to claim 1, characterized in that: The step of summing the areas of the blood oxygen curve below the blood oxygen level within the hypoxia range corresponding to each respiratory event specifically includes: for the blood oxygen curve corresponding to each respiratory event, calculating the area under the curve enclosed by the blood oxygen curve when the blood oxygen curve is below the blood oxygen level within the hypoxia range, and summing the areas under the curve for each respiratory event.

7. The method for calculating hypoxia burden based on polysomnography according to claim 1, characterized in that: In the step of removing the repeatedly calculated area and normalizing the summed area under the curve to accurately calculate the hypoxia burden caused by the respiratory event, during the calculation, it is detected whether the calculated areas of the two respiratory events overlap. If overlap occurs, when calculating the area under the blood oxygen desaturation curve, the repeatedly calculated part in the hypoxia range of the first respiratory event is deleted.

8. The method for calculating hypoxia burden based on polysomnography according to claim 1, characterized in that: In the step of removing the repeatedly calculated areas and standardizing the summed area under the curve to accurately calculate the hypoxia burden caused by respiratory events, the standardization includes: the unit of the summed area under the curve is %*seconds, the unit of the total monitoring time is hours, the standardized area = (area under the curve / 60) / total monitoring time, and the unit of the standardized area is %*minutes / hours.

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