Intermittent hypoxia load prediction method and system for obstructive sleep apnea

Abstract

The invention discloses an intermittent hypoxia load prediction method for obstructive sleep apnea, which comprises the following steps: 1) data acquisition: acquiring oxyhemoglobin saturation information; 2) calculating an intermittent hypoxia index IHI, wherein IHI = S / TST or IHI = S / TRT; wherein S represents the total area under the desaturation curve, TST represents the total sleep time with minute as the unit, and the method is used for polysleep monitoring; tRT represents the total recording time and is used for portable sleep monitoring; iHI represents an intermittent hypoxia index; and 3) determining the intermittent hypoxia load of the obstructive sleep apnea based on the intermittent hypoxia index IHI. The invention provides a new method, namely a Newton-Kittius formula, to calculate the OSA patient nighttime hypoxia load (namely the area under a desaturation curve), and the calculation method has the characteristics that different algebraic precision operation can be performed on data according to the characteristics of the data, so that the result error is small.

Description

Technical Field

[0001] The present invention relates to the field of precision medicine, and in particular to a prediction scheme for intermittent hypoxia load of obstructive sleep apnea. Background Art

[0002] The main feature of obstructive sleep apnea (OSA) is repeated upper airway collapse and obstruction during sleep, which causes repeated hypoxia-reoxygenation, i.e., intermittent hypoxia, which is one of the main pathophysiological mechanisms of OSA-related cardiovascular diseases and metabolic syndrome. The comprehensive indicators used in the current research to comprehensively evaluate intermittent hypoxia include: hypoxic burden HB, hypoxic burden index (HBI), hypoxic load (HL) 100 ) and sleep breathing impairment index (SBII). The core of these index definitions is: the total area under the desaturation curve divided by the total sleep time. Existing reports mainly use the rectangular area formula, trapezoidal area formula and triangular area formula to calculate the total area under the desaturation curve. The introduction of hypoxia load in current research is relatively detailed, and its technical solution is relatively close to the present invention, so this example is used to introduce the existing technical methods.

[0003] Hypoxic load: defined as the total area under the respiratory-related desaturation curve divided by total sleep time (TST), it is a measure of the depth, duration, and frequency of respiratory events. Baseline saturation is defined as the maximum blood oxygen saturation within 100 seconds before the end of the event (apnea or hypopnea). The key to calculating hypoxic load is to calculate the total area under the desaturation curve. The specific steps for calculating hypoxic load are as follows:

[0004] 1) Determination of desaturation events: A decrease in blood oxygen saturation associated with a respiratory event and lower than the baseline saturation is defined as a desaturation event;

[0005] 2) Determine the starting point and end point of the desaturation event: If the blood oxygen saturation related to the respiratory event is lower than the baseline saturation, the time when the blood oxygen saturation is lower than the baseline value is taken as the starting point, and the time when the blood oxygen saturation returns to the baseline value is taken as the end point; for events in which the blood oxygen saturation has not returned to the baseline value, the average oxygen saturation is used as the baseline to determine the starting point and end point.

[0006] 3) Determine the desaturation area: The area enclosed by the oxygen drop curve, reoxygenation curve and baseline saturation is the area under the desaturation curve. The sum of all individual desaturation areas is the total area under the overnight desaturation curve.Figure 1 The shaded area)

[0007] 4) Calculate the total area under the desaturation curve: The figure under the desaturation curve is regarded as a triangle, whose height and base are the depth of the decrease in blood oxygen saturation and its duration, respectively, that is, the area under a single desaturation curve = (desaturation depth × desaturation duration) / 2, and the sum of all single desaturation areas is the total area.

[0008] 5) Calculation of hypoxic load: The hypoxic load can be approximately expressed by multiplying AHI by the area under the mean desaturation curve, HB = AHI × (desaturation depth x desaturation duration) / 2.

[0009] In the current literature reports, the calculation of hypoxic load and respiratory disorder index regards the figure under the nighttime desaturation curve of OSA patients as a triangle; the calculation of hypoxic burden regards it as a trapezoid; the hypoxic load index regards it as a rectangle, and then uses the corresponding area formula to calculate the desaturation area. The triangle area formula calculation method simply regards the area under the desaturation curve as a triangle. This rough calculation leads to large errors in the calculation results; the rectangular area formula calculation method and the trapezoidal area formula calculation method use calculus to divide the figure into countless small figures in units of sampling frequency, and select the corresponding values ​​of each time point as the length and width of the rectangle (or the bottom and height of the trapezoid) to calculate the area. This calculation method has smaller errors than the triangle area formula calculation method, but they all use fixed graphic patterns to simulate and calculate the total area under the desaturation curve. The area under the nighttime desaturation curve of OSA patients is mostly irregular dynamic graphics. The simulation calculation method of the fixed graphic pattern ignores and removes the correlation and volatility between the values, and cannot accurately calculate the patient's true nighttime desaturation area. Summary of the invention

[0010] The present invention aims at the problems existing in the background technology and proposes a prediction scheme for intermittent hypoxia load of obstructive sleep apnea.

[0011] The present invention first discloses a method for predicting intermittent hypoxia load of obstructive sleep apnea, comprising the following steps:

[0012] 1) Data collection, obtaining blood oxygen saturation information;

[0013] 2) Calculate the intermittent hypoxia index IHI, including:

[0014] 2-1) Determine desaturation events. If there is a decrease in blood oxygen saturation and it is lower than the baseline saturation, it is defined as a desaturation event;

[0015] 2-2) Determine the starting and ending points of the desaturation event;

[0016] 2-3) Determine the area under the desaturation curve;

[0017] 2-4) Calculate the total area under the desaturation curve S;

[0018] 2-5) Calculate intermittent hypoxia index IHI:

[0019] IHI=S / TST

[0020] or

[0021] IHI=S / TRT

[0022] Where S represents the total area under the desaturation curve, TST represents the total sleep time in minutes, which is used for polysomnography; TRT represents the total recording time, which is used for portable sleep monitoring; IHI represents the intermittent hypoxia index, unit: %s / min;

[0023] 3) Determine the intermittent hypoxia burden of obstructive sleep apnea based on the intermittent hypoxia index (IHI).

[0024] Preferably, in step 2-1), the baseline value of blood oxygen saturation is set at 90%.

[0025] Preferably, in step 2-2), the time when the blood oxygen saturation is lower than 90% is taken as the starting point, and the time when it recovers to 90% is taken as the end point.

[0026] Preferably, in step 2-2), for events in which the blood oxygen saturation has not recovered to 90%, the starting point and the end point are determined using the average oxygen saturation as a baseline.

[0027] Preferably, in step 2-3), the area of ​​the graph enclosed by the oxygen reduction curve, the reoxygenation curve and the baseline saturation is taken as the area under the desaturation curve.

[0028] Preferably, in step 2-4), the total area under the desaturation curve S is calculated by the following steps:

[0029]

[0030] Where [a,b] represents the integration interval, n represents the equal fraction, f(x) represents the integrand, k represents the node number for the integration, C k (n) represents the Curtis coefficient, t represents the independent variable of the integrand, dt and dx represent the increments of the independent variable of the integrand, and j represents the independent variable of integration in the interval 0-n.

[0031] Preferably, in step 2-5), TST and TRT are automatically generated through sleep monitoring reports.

[0032] Preferably, in step 3), if the patient's intermittent hypoxia index IHI>7.18, it is determined that the patient suffers from intermittent hypoxia.

[0033] Preferably, IHI is 7.178-26.413, indicating that the examinee has mild hypoxia; IHI is 26.413-75.680, indicating that the examinee has moderate hypoxia; IHI is 75.680-136.777, indicating that the examinee has severe hypoxia; IHI>136.777, indicating that the examinee has extremely severe hypoxia.

[0034] The present invention also discloses a system for predicting intermittent hypoxia load of obstructive sleep apnea, wherein the prediction system comprises at least one processor and a memory connected to the processor, wherein:

[0035] The memory is used to store computer programs or instructions;

[0036] The processor is used to obtain and execute the computer program or instructions in the memory so that the prediction system can perform the prediction method.

[0037] Beneficial Effects of the Invention

[0038] 1) The present invention proposes a new method, the Newton-Curtis formula, to calculate the nocturnal hypoxia load (i.e., the area under the desaturation curve) of OSA patients. The characteristic of this calculation method is that it can perform different algebraic precision operations on the data according to the characteristics of the data, so the error of the result is small;

[0039] 2) When performing calculations, this new method will take into account the impact of changes before and after the data on the overall value, and has advantages in some extreme data. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram for determining the desaturation area in the background technology

[0041] Figure 2 The prediction method flow chart of the present invention is DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with embodiments, but the protection scope of the present invention is not limited thereto:

[0043] 1) Data collection: Before calculating the intermittent hypoxia index, it is necessary to extract the blood oxygen saturation information of OSA patients throughout the night. These patients must first undergo polysomnography (PSG) or home portable sleep monitoring (HSAT). The blood oxygen saturation is extracted in the following ways:

[0044] The present invention introduces the specific collection process of Philips Alice5 and Alice6: open the G3 software, click File → Open, find the location where the file is stored, select the patient to be analyzed, double-click the left mouse button to open the selected patient, click File → Export → Raw Data → Channel → Certain Channels → SPO2 → Time → Entire Study → Format → CSV File (Actual Value) again, select the location to be exported, and then the blood oxygen saturation information can be exported.

[0045] 2) Calculation of intermittent hypoxia index: The specific steps are as follows:

[0046] ① Determine desaturation events: If there is a decrease in blood oxygen saturation and it is lower than the baseline saturation, it is defined as a desaturation event. Studies have shown that when the oxygen saturation is >90%, the oxygen partial pressure value is >60mmHg, and a slight decrease in blood oxygen will not affect the physiological function of cells and should not be regarded as hypoxia. The prognosis and characteristics of OSA are closely related to blood oxygen saturation <90%. Therefore, we set the baseline value of blood oxygen saturation to 90%.

[0047] ② Determine the starting point and end point of the desaturation event: If the blood oxygen saturation is lower than the baseline saturation, the time when the blood oxygen saturation is lower than 90% is taken as the starting point, and the time when it recovers to 90% is taken as the end point; for events in which the blood oxygen saturation does not recover to 90%, the average oxygen saturation is used as the baseline to determine the starting point and end point.

[0048] ③ Determine the desaturation area: The area enclosed by the oxygen drop curve, reoxygenation curve and baseline saturation is the area under the desaturation curve. The sum of all desaturation areas is the total area under the desaturation curve for the entire night.

[0049] ④. Calculate the total area under the desaturation curve: As mentioned above, the area under the desaturation curve formed by intermittent hypoxia at night in OSA patients is mostly an irregular dynamic change graph. Therefore, the present invention introduces a new calculation method, that is, using the Newton-Curtis formula to calculate the area under the desaturation curve. The formula is as follows:

[0050]

[0051]

[0052] Formula explanation:

[0053] [a,b]—integral interval

[0054] n—equal fraction

[0055] F(x)—integrand

[0056] P(x) — approximate function

[0057] A k—Production coefficient

[0058] K—Integration node number

[0059] C k (n) —Curtis coefficient

[0060] t—integrand function independent variable

[0061] j—integral independent variable in the interval 0-n

[0062] dt, dx—increments of the independent variables of the integrand

[0063] It can be seen from the above formula that the Newton-Curtis formula can have multiple algebraic precision, so it has good stability and smaller error.

[0064] ⑤. Calculate the intermittent hypoxia index (IHI): IHI = total area under the desaturation curve calculated using the Newton-Curtis formula / total sleep time (TST) in minutes. TST is obtained from the sleep monitoring report. In other embodiments, the total sleep time (TST) is replaced with the total recording time (TRT), which can achieve similar results.

[0065] ⑥ Output IHI (if using excel, identify each desaturation event, and then use its sum function to calculate the area of ​​each individual event, add up the individual areas to get the total area, and then divide it by TST to get IHI).

[0066] 3) Determine the intermittent hypoxia burden of obstructive sleep apnea based on the intermittent hypoxia index (IHI).

[0067] 3-1) Using the examinee's lowest blood oxygen saturation MinSpO2 throughout the night as the standard, determine whether there is intermittent hypoxia: Use the SPSS26 system to analyze the critical value of intermittent hypoxia at night, the steps are: open SPSS26→Analysis→Classification→ROC curve, use IHI as the test variable, and whether there is intermittent hypoxia as the state variable ("1" represents the whole night MinSpO2 <90%, the examinee has intermittent hypoxia, "0" represents the examinee does not have hypoxia.) Finally, the AUC of the ROC curve was 0.937 (95% confidence interval 0.913-0.960, p<0.001), and the critical value of IHI for diagnosing intermittent hypoxia was 7.178 (that is, when IHI>7.178, it indicates that the examinee has intermittent hypoxia, and when IHI<7.178, it indicates that the examinee does not have intermittent hypoxia).

[0068] 3-2) X-tile software was used to grade the severity of patients with IHI>7.178. An IHI of 7.178 (%s / min)-26.413 (%s / min) indicated mild hypoxia; an IHI of 26.413 (%s / min)-75.680 (%s / min) indicated moderate hypoxia; an IHI of 75.680 (%s / min)-136.777 (%s / min) indicated severe hypoxia; and an IHI>136.777 (%s / min) indicated extreme hypoxia.

[0069] The present invention also discloses a system for predicting intermittent hypoxia load of obstructive sleep apnea, wherein the prediction system comprises at least one processor and a memory connected to the processor, wherein:

[0070] The memory is used to store computer programs or instructions;

[0071] The processor is used to obtain and execute the computer program or instructions in the memory so that the prediction system can perform the prediction method.

[0072] 1) The present invention proposes a new method, the Newton-Curtis formula, to calculate the nocturnal hypoxia load (i.e., the area under the desaturation curve) of OSA patients. The characteristic of this calculation method is that it can perform different algebraic precision operations on the data according to the characteristics of the data, so the error of the result is small;

[0073] 2) When performing calculations, this new method will take into account the impact of changes before and after the data on the overall value, and has advantages in some extreme data.

[0074] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A method for predicting intermittent hypoxia load in obstructive sleep apnea, Features It includes the following steps: 1) Data collection, obtaining blood oxygen saturation information; 2) Calculate the intermittent hypoxia index IHI, including: 2-1) Determine desaturation events. If there is a decrease in blood oxygen saturation and it is lower than the baseline saturation, it is defined as a desaturation event; 2-2) Determine the starting and ending points of the desaturation event; 2-3) Determine the area under the desaturation curve; 2-4) Calculate the total area under the desaturation curve S; 2-5) Calculate intermittent hypoxia index IHI: IHI=S / TST or IHI=S / TRT Where S represents the total area under the desaturation curve, TST represents the total sleep time in minutes, which is used for polysomnography; TRT represents the total recording time, which is used for portable sleep monitoring; IHI represents the intermittent hypoxia index, unit: %s / min; 3) Determine the intermittent hypoxia burden of obstructive sleep apnea based on the intermittent hypoxia index (IHI).

2. The method according to claim 1, Features In step 2-1), the baseline value of blood oxygen saturation is set to 90%.

3. The method according to claim 1, Features In step 2-2), the time when the blood oxygen saturation is lower than 90% is taken as the starting point, and the time when it recovers to 90% is taken as the end point.

4. The method according to claim 3, Features In step 2-2), for events in which the blood oxygen saturation has not recovered to 90%, the starting point and the end point are determined using the average blood oxygen saturation as a baseline.

5. The method according to claim 1, Features In step 2-3), the area of ​​the graph enclosed by the oxygen reduction curve, the reoxygenation curve and the baseline saturation is taken as the area under the desaturation curve.

6. The method according to claim 1, Features In step 2-4), the total area under the desaturation curve S is calculated by the following steps: Where [a,b] represents the integration interval, n represents the equal fraction, f(x) represents the integrand, k represents the node number for the integration, C k (n) represents the Curtis coefficient, t represents the independent variable of the integrand, dt and dx represent the increments of the independent variable of the integrand, and j represents the independent variable of integration in the interval 0-n.

7. The method according to claim 1, Features In step 2-5), TST and TRT are automatically generated through the sleep monitoring report.

8. The method according to claim 1, Features In step 3), if the patient's intermittent hypoxia index IHI>7.18, it is determined that the patient suffers from intermittent hypoxia.

9. The method according to claim 8, Features An IHI of 7.178-26.413 indicates mild hypoxia; an IHI of 26.413-75.680 indicates moderate hypoxia; an IHI of 75.680-136.777 indicates severe hypoxia; and an IHI>136.777 indicates extreme hypoxia.

10. A system for predicting intermittent hypoxia load in obstructive sleep apnea. Features: The prediction system comprises at least one processor and a memory connected to the processor, wherein: The memory is used to store computer programs or instructions; The processor is used to obtain and execute the computer program or instructions in the memory so that the prediction system performs the prediction method according to claims 1-8.

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