A method for non-invasive monitoring of gastric residual volume by pressure-volume model and a gastric tube

Abstract

The present application belongs to medical information processing technology, and particularly relates to a method for non-invasive monitoring of gastric residual volume through a pressure-volume model, which comprises the following steps: a sensor is arranged at the end of a gastric tube, a certain amount of gas is filled into the end, the pressure of the end is measured, the end is completely immersed into gastric juice, the pressure of the end is measured to obtain the depth difference of the gastric juice, and the actual gastric juice depth of a patient is obtained according to different times, and the depth difference can be used to infer the strength of the digestive function of the patient. In the method, the gas pressure is used, the principle that the liquid pressure is only related to the liquid depth is used, the gastric residual volume is converted into the pressure of the gas, the pressure difference is measured by using a corresponding gas sensing device, and thus the gastric residual volume of the patient is calculated, and the gastric digestion function of the patient is obtained.

Description

Technical Field

[0001] This invention belongs to the field of medical information processing technology, specifically a method and gastric tube for non-invasive monitoring of gastric residual volume using a pressure-volume model. Background Technology

[0002] For the human body, the stomach's normal digestive and absorptive functions are essential to obtain nutrients and energy, maintaining normal metabolic activity. However, for critically ill patients, due to medication effects, stress responses, and other issues, gastric motility disorders are common, affecting intestinal peristalsis and gut microbiota balance, leading to malnutrition and infectious complications. Therefore, it is necessary to assess the stomach's digestive capacity promptly.

[0003] Currently, the main methods for assessing the digestive function of critically ill patients in clinical practice include observation, gastric residual volume monitoring, and medical examinations. Among these, gastric residual volume is the core objective indicator of digestive function. Gastric residual volume monitoring involves extracting gastric contents through a nasogastric tube / nasoenteric tube and measuring the volume of the residual contents. The monitoring frequency is generally around 6 hours. The monitoring index is that a single residual volume >200ml or two consecutive residual volumes >150ml in an adult fasting state indicates delayed gastric emptying, i.e., decreased digestive capacity.

[0004] Therefore, monitoring gastric residual volume requires the removal of nutrients from the stomach of critically ill patients for assessment. The empty stomach will cause obvious discomfort to the patient, and digestive juices will also be removed. Subsequently, it is necessary to supplement the critically ill patient with an appropriate amount of nutrients, which will increase the patient's digestive burden and delay the patient's recovery. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a method and gastric tube for non-invasive monitoring of gastric residual volume using a pressure-volume model. The gastric tube is equipped with an air bladder at its end. Pressure within the gastric fluid causes pressure changes within the air bladder. The gastric fluid depth is calculated using the air bladder pressure data, thereby establishing a model of gastric fluid depth and gastric volume. This model can reflect the patient's digestive function level, simplifies the operation, and is quick and convenient, thus avoiding frequent extraction of gastric residual material.

[0006] A method for noninvasively monitoring gastric residual volume using a pressure-volume model includes the following steps: S1) A sensor is installed at the end of the gastric tube. A certain amount of gas is introduced into the end, and the pressure at the end is measured. ; S2) The tip is completely immersed in gastric juice, and the pressure of the tip is measured. The depth difference of gastric juice for: , Where: air pressure difference , The density of gastric juice, It is the gravitational constant; the concentrations of gastric juice and medical nutrient solution in the human body remain essentially constant, so the density of gastric juice can be... Treat it as a constant; S3) According to different times Obtain the patient's actual gastric fluid depth This leads to the depth difference. This can indicate the strength or weakness of a patient's digestive function.

[0007] In step S1 above, it is necessary to apply pressure to the end. The sensor is calibrated and its error is corrected when the device is fasting. The specific method is as follows: S1.1) The subject was fasting, and gastric pressure was measured. n Each measurement recorded the intragastric pressure as follows: During multiple measurements, the subject's position should remain unchanged, and the average value should be taken as follows: ; S1.2) Use the gastric tube to measure the pressure in the stomach of the subject, and measure the pressure a number of times. n Each time, the intragastric pressure was measured. The average value is: ; S1.3) The measurement difference of the sensor under fasting conditions is It is used to correct errors in the gastric tube when the patient is fasting.

[0008] In step S2 above, it is necessary to apply pressure to the end. Calibration is performed to correct sensor errors during digestion. The specific method is as follows: S2.1) Inject a certain volume of nutrient solution into the stomach of the subject, and repeat steps S2.11 to S2.13 to obtain the average pressure of the medical gastric pressure measuring device. And the mean pressure of the gastric tube in this application , recorded as ; S2.2) Repeat step S2.14 above. z Each measurement difference is recorded as [number]. The measurement difference of the sensor under digestion state was obtained as follows: This is used to correct sensor errors in the gastric tube of this application during digestion of the tested object.

[0009] In step S2 above, the gastric juice depth This is achieved by establishing a mathematical model of intragastric pressure and gastric fluid volume. The specific method is as follows: S2.3) Measure gastric pressure during fasting. At this time, there is no liquid in the stomach. It's merely the formation of stomach wall tension; S2.4) Inject the volume into the stomach in several portions. , , ··· The liquid was injected, and the intragastric pressure was recorded after a certain period of time. , , ... ,get The curve, obtained by linear regression or curve fitting, represents the relationship between gastric fluid volume and intragastric pressure. The calibration formula is: ; At the target time point, the intragastric pressure was recorded using a pressure sensor. (Record continuously for 5 minutes, take the average value, and exclude pressure fluctuations caused by gastric peristalsis), and then calculate the actual pressure. Substituting the above The calibration formula calculates the volume of fluid in the stomach at this time. The actual volume of gastric juice remaining in the stomach ,in It is the equivalent volume of the stomach when fasting; S2.5) Based on gastric juice volume Obtain the corresponding gastric juice depth The specific method is as follows: record the intragastric pressure value before injecting the nutrient solution. The gastric juice depth at this time can be calculated. ; at an injection volume of The depth of gastric juice (depth of fluid in the antrum) after nutrient solution administration is denoted as According to step S2.2, during injection Record the corresponding measured pressure after 1 minute. Then the corresponding gastric juice depth can be calculated. for: .

[0010] In step S3) above, based on the gastric juice depth The methods for assessing digestive function are as follows: Gastric emptying rate at a specific time point Quantification The percentage of nutrient solution emptied within minutes out of the initial total volume is calculated using the following formula: , venting rate It is divided into average rate and segmented rate. The average emptying rate is from 0 minutes to... The formula for calculating the average volume of test water emptied per minute is as follows: .

[0011] The present invention also provides a gastric tube used in the above-mentioned non-invasive method for monitoring gastric residual volume, comprising a tube body, a gas channel and an air bladder. The tube body has a feeding port at the front and several outlets at the rear. The air bladder is located at the rear end of the tube body and the two are sealed. The gas channel extends along the tube wall of the tube body. The front end of the gas channel is close to the feeding port and the rear end is connected to the air bladder. The air bladder can be inflated or deflated through the gas channel. The air pressure value in the air bladder is measured by a pressure sensor.

[0012] In the aforementioned gastric tube, the pressure sensor is located inside the air bladder or at the front end of the gas channel.

[0013] The aforementioned gastric tube has a gravity block inside the air sac.

[0014] The aforementioned gastric tube, wherein the tube body, gas passage, and air bladder are integrally molded and made of any one of silicone, rubber, or polyurethane.

[0015] This invention uses gas pressure to convert the patient's gastric residual volume into gas pressure based on the principle that liquid pressure is only related to the liquid depth. Then, a corresponding gas sensing device is used to measure the pressure difference to calculate the patient's gastric residual volume and obtain the patient's gastric digestive function. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the inflation and usage state of Embodiment 1 of the present invention; Figures 3 to 5 The PV data of three different patients in Embodiment 2 of the present invention are illustrated (the horizontal axis is the gastric volume, the vertical axis is the pressure value, the dashed line is the ideal state, and the small dots are the measured data).

[0017] In the diagram: 1 is the tube body, 2 is the outlet, 3 is the gas passage, 4 is the air bladder, and 5 is the gravity block. Detailed Implementation

[0018] The technical solution of the present invention will be explained in detail below with reference to the accompanying drawings. The following embodiments are illustrative; unless otherwise specifically stated, the relative arrangement and numerical expressions of components and steps described in these embodiments should not be construed as limiting the scope of the present invention. The following description of exemplary embodiments is merely illustrative and is not intended to limit the present invention or its application or use in any way. Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail here, but where applicable, such techniques, methods, and apparatus should be considered part of this specification.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. Unless otherwise stated, the terms "installed," "connected," "linked," "fixed," etc., in this invention should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to an internal connection between two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0020] For ease of description, the terms "upper," "lower," "left," "right," and "bottom" appear in this invention. These terms do not limit the structure but are merely for the purpose of understanding the structural principles of the invention in conjunction with the accompanying drawings. They do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and should not be construed as a limitation of the invention.

[0021] Example 1 This embodiment is a gastric tube, including a tube body 1, a gas channel 3, and an air bladder 4. The tube body 1 has a feeding port at the front and several outlets 2 at the rear. The air bladder 4 is located at the rear end of the tube body 1 and the two are sealed. The gas channel 3 extends along the tube wall of the tube body 1. The front end of the gas channel 3 is close to the feeding port and the rear end is connected to the air bladder 4. The air bladder 4 can be inflated or deflated through the gas channel 3. The air pressure value inside the air bladder 4 is measured by a pressure sensor.

[0022] The gastric tube described above has a pressure sensor located inside the air bladder 4 or at the front end of the gas channel 3.

[0023] The gastric tube described above has a gravity block 5 inside the air sac 4.

[0024] The aforementioned gastric tube, wherein the tube body 1, the gas channel 3, and the air bladder 4 are integrally formed and are made of any one of silicone, rubber, or polyurethane.

[0025] Example 2 A method for monitoring gastric digestive function, using the aforementioned gastric tube, includes the following steps: S1) A certain amount of gas is inflated into the airbag 4, and the pressure of the airbag 4 is measured. ; S2) Insert the rear part of tube 1 into the stomach, so that the air bladder 4 is completely immersed in the gastric juice, and measure the pressure of the air bladder 4. Because the pressure of the liquid inside the container is related to the depth of the liquid, Calculate the depth difference of gastric juice (This is equivalent to measuring the depth of gastric juice in a fasting person) is: , Where: air pressure difference , The density of gastric juice, It is the gravitational constant; the concentrations of gastric juice and medical nutrient solution in the human body remain essentially constant, so the density of gastric juice can be... Treat it as a constant; S3) According to different times Obtain the patient's actual gastric fluid depth And obtain the depth difference This can indicate the strength or weakness of a patient's digestive function.

[0026] In step S1 above, the pressure of the airbag 4 needs to be adjusted. Calibration is performed to correct sensor errors when fasting. The specific method is as follows: S1.1) The subject is fasting, and a conventional medical gastric pressure measurement device, such as a catheter with a pressure sensor, is inserted into the stomach through the mouth or nose for measurement. This is an invasive, non-invasive measurement of gastric pressure. n Each measurement recorded the intragastric pressure as follows: During multiple measurements, the subject's position should remain unchanged, and the average value should be taken as follows: ; S1.2) After the above data measurements are completed, the gastric tube of this application is used to measure the pressure in the stomach of the subject. The number of measurements is as follows: n Each time, the intragastric pressure was measured. The average value is: ; S1.3) The measurement difference of the sensor under fasting conditions is This is used to correct sensor errors in the gastric tube of this application when the tested subject is fasting.

[0027] In step S2 above, the pressure of the airbag 4 needs to be adjusted. Calibration is performed to correct sensor errors during digestion. The specific method is as follows: S1.4) Inject a certain volume of nutrient solution into the stomach of the subject, and repeat steps S2.11 to S2.13 to obtain the average pressure of the medical gastric pressure measuring device. And the mean pressure of the gastric tube in this application , recorded as ; S1.5) Repeat step S2.14 above. z Each measurement difference is recorded as [number]. The measurement difference of the sensor under digestion state was obtained as follows: This is used to correct sensor errors in the gastric tube of this application during digestion of the tested object.

[0028] In step S2 above, the gastric juice depth This is achieved by establishing a mathematical model of intragastric pressure and gastric fluid volume. The specific method is as follows: S2.1) Measure gastric pressure during fasting. At this time, there is no liquid in the stomach. It's merely the formation of stomach wall tension; S2.2) Inject the volume into the stomach in several portions of [volume]. , , ··· The liquid was injected, and the intragastric pressure was recorded after a certain period of time. , , ... ,get The curve, obtained by linear regression or curve fitting, represents the relationship between gastric fluid volume and intragastric pressure. The calibration formula is: ; Among them, using To perform fitting, specifically: slope , intercept , In the formula: It can be used To measure the effect, the closer it is to 1, the better the fit.

[0029] Using the gastric tube of this invention, the intragastric pressure is recorded at target time points (e.g., 30 minutes and 120 minutes after drinking the nutrient solution) via a pressure sensor. (Record continuously for 5 minutes, take the average value, and exclude pressure fluctuations caused by gastric peristalsis), and then calculate the actual pressure. Substituting the above The calibration formula calculates the volume of fluid in the stomach at this time. So, the actual volume of gastric juice remaining in the stomach ,in It is the equivalent volume (volume) of the stomach when fasting.

[0030] The depth of remaining gastric juice in the stomach Essentially, it refers to the maximum vertical depth of gastric juice in a longitudinal section of the gastric antrum. To establish the relationship between gastric juice depth and volume, only the "gastric antrum" is used as the measurement area (the gastric antrum is the main channel for fluid emptying, with a relatively regular shape and less affected by gastric peristalsis): the gastric antrum fluid area is approximated as part of a cylinder (circular in cross-section and rectangular in longitudinal section), i.e., the gastric juice volume. =Cross-sectional area of ​​the gastric antrum ×Gastric juice depth For the same subject, the cross-sectional area of ​​the gastric antrum... Within a short period (120-minute test period), the values ​​are fixed (unaffected by fluid volume, only related to individual gastric anatomy). In a transverse section of the gastric antrum, the anteroposterior diameter D1 and lateral diameter D2 of the gastric antrum are measured, and the cross-sectional area of ​​the gastric antrum is calculated using the ellipse area formula. Therefore, the volume of gastric juice Its depth It is strictly proportional.

[0031] like Figures 3 to 5 As shown, the three sets of PV data are graphs of healthy stomach, mild gastric motility (such as indigestion, elderly people), and moderate gastric motility (such as chronic atrophic gastritis). In the three sets of data graphs, the dashed line represents the ideal state and the small dots represent the measured data. They are all very close to the dashed line. Therefore, the method in step 2.2 is relatively accurate.

[0032] S2.3) Based on gastric juice volume Obtain the corresponding gastric juice depth The specific method is as follows: record the intragastric pressure value before injecting the nutrient solution. This allows us to calculate the depth of gastric juice at that point. ; at an injection volume of The depth of gastric juice (depth of fluid in the antrum) after nutrient solution administration is denoted as According to step S2.2, during injection Record the corresponding measured pressure after 1 minute. Then the corresponding gastric juice depth can be calculated. for: .

[0033] In step S3) above, based on the gastric juice depth The methods for assessing digestive function are as follows: Gastric emptying rate at a specific time point Quantification The percentage of nutrient solution emptied within minutes out of the initial total volume directly reflects digestion efficiency. The formula for calculating the emptying rate is: , venting rate The overall gastric emptying function is further quantified by dividing it into average rate and segmented rate. The average emptying rate is from 0 minutes to... The formula for calculating the average volume of test water emptied per minute is as follows: , The segmented rate is determined by taking different values ​​based on the above average emptying rate formula. This allows for the measurement of digestive function levels over a specific time period.

[0034] The above are merely preferred embodiments of this application. It should be noted that, for those skilled in the art, several structural changes or improvements can be made without departing from the principles of this application, and these changes or improvements should also be considered within the scope of protection of this application.

Claims

1. A method for non-invasive monitoring of gastric residual volume using a pressure-volume model, characterized in that, Includes the following steps: S1) A sensor is installed at the end of the gastric tube. A certain amount of gas is introduced into the end, and the pressure at the end is measured. ; S2) The tip is completely immersed in gastric juice, and the pressure of the tip is measured. The depth difference of gastric juice for: ， Where: air pressure difference , The density of gastric juice, It is the gravitational constant; S3) According to different times Obtain the patient's actual gastric fluid depth This leads to the depth difference. This can indicate the strength or weakness of a patient's digestive function.

2. The method for non-invasive monitoring of gastric residual volume using a pressure-volume model according to claim 1, characterized in that, In step S1 above, the pressure on the end Calibration is performed to correct the sensor's error when the device is fasting. The specific method is as follows: S1.1) The subject was fasting, and gastric pressure was measured. n The gastric pressure was measured in several measurements, with each measurement being [value missing]. During multiple measurements, the subject's position should remain unchanged, and the average value should be taken as follows: ； S1.2) The pressure in the stomach of the subject is measured using the gastric tube, and the number of measurements is: n Each time, the intragastric pressure was measured. The average value is: ； S1.3) The measurement difference of the sensor under fasting conditions is It is used to correct errors in the gastric tube when the patient is fasting.

3. The method for non-invasive monitoring of gastric residual volume using a pressure-volume model according to claim 2, characterized in that, In step S2 above, the pressure on the end Calibration is performed to correct sensor errors during digestion. The specific method is as follows: S2.1) Inject a certain volume of nutrient solution into the stomach of the subject, and repeat steps S2.11 to S2.13 to obtain the average pressure of the medical gastric pressure measuring device. And the mean pressure of the gastric tube in this application , recorded as ; S2.2) Repeat step S2.14 above. z Each measurement difference is recorded as [number]. The measurement difference of the sensor under digestion conditions was obtained as follows: This is used to correct sensor errors in the gastric tube of this application during digestion of the tested object.

4. The method for non-invasive monitoring of gastric residual volume using a pressure-volume model according to claim 1, characterized in that, In step S2 above, the gastric juice depth This is achieved by establishing a mathematical model of intragastric pressure and gastric fluid volume. The specific method is as follows: S2.3) Measure gastric pressure during fasting. ; S2.4) Inject the volume into the stomach in several portions. , , ··· The liquid was injected, and the intragastric pressure was recorded after a certain period of time. , , ... ,get The curve, obtained by linear regression or curve fitting, represents the relationship between gastric fluid volume and intragastric pressure. The calibration formula is: ； At the target time point, the intragastric pressure was recorded using a pressure sensor. The measured pressure Substituting the above The calibration formula calculates the volume of fluid in the stomach at this time. The actual volume of gastric juice remaining in the stomach ,in It is the equivalent volume of the stomach when fasting; S2.5) Based on gastric juice volume Obtain the corresponding gastric juice depth The specific method is as follows: record the intragastric pressure value before injecting the nutrient solution. The gastric juice depth at this time is obtained. ; at an injection volume of The depth of gastric juice (depth of fluid in the antrum) after nutrient solution is recorded as According to step S2.2, during injection Record the corresponding measured pressure after 1 minute. Then the corresponding gastric juice depth can be calculated. for: 。 5. The method for non-invasive monitoring of gastric residual volume using a pressure-volume model according to claim 1, characterized in that, In step S3 above, based on the gastric juice depth The methods for assessing digestive function are as follows: Gastric emptying rate at a specific time point Quantification The percentage of nutrient solution emptied within minutes out of the initial total volume is calculated using the following formula: ， venting rate It is divided into average rate and segmented rate. The average emptying rate is from 0 minutes to... The formula for calculating the average volume of test water emptied per minute is as follows: 。 6. A gastric tube used in the non-invasive method for monitoring gastric residual volume as described in any one of claims 1 to 5, characterized in that: It includes a tube body (1), a gas channel (3) and an air bladder (4). The tube body (1) has a feeding port at the front and several outlets (2) at the rear. The air bladder (4) is located at the end of the tube body (1) and the two are sealed. The gas channel (3) extends along the tube wall of the tube body (1). The front end of the gas channel (3) is close to the feeding port and the rear end is connected to the air bladder (4). The air bladder (4) can be inflated or deflated through the gas channel (3). The air pressure value inside the air bladder (4) is measured by a pressure sensor.

7. The gastric tube according to claim 6, characterized in that: The pressure sensor is located inside the airbag (4) or at the front end of the gas channel (3).

8. The gastric tube according to claim 6, characterized in that: The airbag (4) contains a gravity block (5).

9. The gastric tube according to claim 6, characterized in that: The tube (1), gas channel (3) and airbag (4) are integrally formed and are made of any one of silicone, rubber or polyurethane.

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