KR20200021647A - Method for automatic controlling a fraction of inspired oxygen of medical ventilator - Google Patents

Abstract

The present invention relates to an automatic control method of inhaled oxygen concentration in a respirator, which controls inhaled oxygen concentration (FiO2) automatically depending on the situation by comparing target blood oxygen saturation and inhaled oxygen saturation (SpO2) measured in a patient within a range of the inhaled oxygen concentration (FiO2) prescribed by a doctor. In particular, the present invention relates to an automatic control method of inhaled oxygen concentration in a respirator, which automatically determines FiO2 from a biosignal measured from the patient, thereby having clinical advantages.

Description

Method for automatic controlling a fraction of inspired oxygen of medical ventilator}

The present invention relates to a method for automatically controlling the FRP (Fraction of inspired oxygen concentration) of the respirator, and more particularly, the blood saturation (Saturation of blood) measured in the patient within the range of FiO2 prescribed by the doctor Comparing partial pressure oxygen (SPO2) measurements with preset SpO2 targets, FiO2 control values are automatically determined and supplied to patients to prevent hypoxia and O ₂ toxicity. In addition, the present invention relates to a method for automatically controlling the inhalation oxygen concentration of the ventilator, which can further improve the convenience of the ventilator.

In general, the ventilator is a means of artificially supplying a mixed gas of oxygen and air to the patient to maintain life in the treatment of the patient, and in recent years, the injury of the alveoli under pressure while maintaining comfort to the patient during the artificial respiration Research is underway to minimize structural damage to the airways.

Looking at the trend of technology development for the ventilator, the study on gas exchange method was mainly focused in the 80s, the study on the ventilation supply method was attracting attention in the 90s, and recently, to reduce the damage of the lungs and to effectively spontaneously breathe There is a growing interest in research that can lead to this.

According to this development trend, a pressure-controlled multifunctional ventilator has been developed, and this pressure-controlled ventilator can reduce alveolar-capillary damage and induce spontaneous breathing of apnea patients quickly.

The method of administering oxygen in the treatment of patients is divided into hyperbaric oxygen therapy and low flow oxygen therapy according to the amount of gas supplied to the patient's breathing. In other words, hyperbaric oxygen therapy is a method of delivering oxygen to various parts of our body through capillaries by allowing the patient to breathe 100% high purity oxygen in a chamber with an artificial environment of 2 to 4 atmospheres above atmospheric pressure. to be. In addition, low-flow oxygen therapy supplies oxygen at a lower flow rate than the patient's inspiration needs, using a nasal cannula, a simple O ₂ mask, and a mask with reservoir bag. It is a treatment method to supply oxygen of 4L or less.

As described above, oxygen administration using a respirator is generally known to be performed when arterial blood oxygen partial pressure of a patient is 60 mmHg or less, or arterial blood oxygen saturation is 90% or less.

Looking at the prior art for the ventilator, Republic of Korea Patent Publication No. 10-1333195 (Nov. 26, 2013), the inhalation breathing day by supplying the heated and humidified oxygen through the nose at a flow rate exceeding the patient's Non-invasive, ultimately reducing patient breathing and improving pulmonary oxygenation by reducing neutrophils, generating end-tidal positive pressure, increasing functional residues, optimizing mucosal conditions in the nasal and upper airways, and reducing anaerobic respiratory residual gas A nasal interface for oxygen therapy respiratory therapy is disclosed.

In addition, the Republic of Korea Patent Publication No. 10-2018-0041535 (2018. 04. 24.) is provided with an air outlet on one side, the oxygen supply port is formed so that a separate oxygen supply is connected to the other side, to the user An air bag that can be inflated and extruded to expel oxygen to be supplied; A mask in which an oxygen inlet is formed to directly supply oxygen discharged from the air bag to the user, and the mask is formed to be in close contact with the face of the user; An oxygen delivery tube coupled to an oxygen inlet of the mask and connected to the air bag to deliver oxygen discharged from the air bag to the oxygen inlet; A flow rate sensor provided in the oxygen transfer pipe and sensing a flow rate of oxygen supplied to the user; A data processing device electrically connected to the flow rate sensor to calculate a flow rate detected by the flow rate sensor; And a flow rate control device formed on one side of the oxygen delivery pipe to supply a uniform amount of oxygen to the user by adjusting the flow rate range based on the flow rate data calculated through the data processing device. The present invention relates to a manual ventilator capable of adjusting a flow rate through feedback and a ventilation injection method using the same.

However, in the prior art, since FiO ₂ varies according to the patient's breathing pattern and oxygen (O ₂ ) flow rate, it is difficult to supply accurate FiO ₂ . Accordingly, when excess oxygen is supplied, the patient may be exposed to oxygen (O ₂ ) toxicity, and when a small amount of oxygen is supplied, the patient may be exposed to the risk of hypoxia. In addition, such a conventional ventilator has been inconvenient to always monitor the biological signal including oxygen saturation, and to manually control the ventilator according to the monitoring result.

The present invention was created to solve the above problems, and compares the SpO2 measurement value measured by the patient in the FiO2 range prescribed by the doctor with the target SpO2 target value, and automatically adjusts the concentration of FiO2 according to the situation. The present invention relates to a method for automatically controlling the inhalation oxygen concentration of a ventilator for controlling. In particular, the present invention relates to a method for automatically controlling the inhalation oxygen concentration of a respirator having many clinical advantages by automatically determining FiO 2 from SpO 2 measured values from a patient and thus being applicable to hyperbaric oxygen therapy and low flow oxygen therapy.

The automatic control method of the inhalation oxygen concentration of the oxygen therapy respirator of the present invention for solving the above problems comprises the steps of inputting a target value of the blood oxygen saturation degree and the set value of the intake oxygen concentration (S-10); Measuring blood oxygen saturation of the patient (S-20); Verifying the effectiveness of the measured blood oxygen saturation degree (S-30); Comparing the target value of the blood oxygen saturation degree with the blood oxygen saturation measurement value (S-40); Determining the type of the patient (S-50); Determining an inspiratory oxygen concentration control value supplied to the patient through steps S-40 and S-50 (S-60); And supplying oxygen according to the intake oxygen concentration control value (S-80). The target value of the oxygen saturation in the blood is 80 to 96%, and the lower limit of the intake oxygen concentration is 21 to. It is 96%, and it is preferable that an upper limit is 25 to 100%. In addition, in step S-20, it is preferable to determine the inspiratory oxygen concentration control value at 30 second intervals for adults and 15 second intervals for children, based on a comparison between the blood oxygen saturation target value and the blood oxygen saturation measurement value. When the blood oxygen saturation measurement value measured in step S-20 is not valid, oxygen is supplied to a predetermined intake oxygen concentration setting value, and the preset intake oxygen concentration setting value is 60%.

As described above, the automatic control method of the inhalation oxygen concentration of the ventilator according to the present invention has the effect of eliminating the discomfort of the medical staff to manually control the parameters of the ventilator by manually adjusting the concentration of FiO2. . In addition, since the change in the required oxygen flow rate is automatically adjusted according to the condition of the patient, it has the effect of maintaining a constant inhalation oxygen concentration that varies depending on the patient breathing pattern. In particular, it is possible to determine FiO2 accurately by automatically calculating FiO2 control values from SpO2 measured values from patients, and have the effect of preventing oxygen toxicity and hypoxia due to incorrect supply of oxygen.

1 is a flow chart showing a method for automatically controlling the inhalation oxygen concentration of the ventilator according to an embodiment of the present invention,
2 is a graph showing an automatic control process of the inhalation oxygen concentration of the ventilator according to an embodiment of the present invention.

Hereinafter, an experimental example of the present invention with reference to the accompanying drawings in detail as follows. However, the present invention is not limited to the experimental examples disclosed below, but may be embodied in various forms. The following experimental examples make the disclosure of the present invention complete and the scope of the invention to those skilled in the art. It is provided to inform you completely. In addition, the components may be exaggerated or reduced in size in the drawings for convenience of description. In the drawings, for example, variations in the shape shown may be expected, depending on manufacturing techniques and / or tolerances. Thus, the experimental example of the inventive concept should not be construed as limited to the specific shapes of the regions shown herein, but should include, for example, changes in shape resulting from manufacturing.

In the present invention, SpO2 refers to the amount of oxygen bound to hemoglobin in the blood, which indicates the amount of oxygen carried by red blood cells. In other words, the measurement of SpO2 indicates how effectively the patient breathes and displays the measurement in percent. These normal measurements of SpO2 are 97-99% in adults and 94-98% in children.

Typically, SpO2 is measured by a pulse oximeter (pulse oximeter) composed of a computerized monitor and a detector, and the pulse oximeter is attached to a finger, toe, or ear of a patient. However, SpO2 decreases the reliability of the measured value when the patient moves when there is severe hypothermia, anemia, blood circulation disorders such as peripheral blood vessel contraction, and strong light around the patient.

In addition, FiO2 indicates the concentration of oxygen in the inhalation of the patient, and indicates the concentration of oxygen contained in the air when the patient inhales, expressed as a percentage. High levels of FiO2 supplied to patients during oxygen therapy may expose them to O2 toxicity and may cause lung failure. Conversely, if the FiO2 supplied to the patient is low, the patient is at risk of hypoxia.

Hereinafter, an automatic control method of an inhalation oxygen concentration of a respirator according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 1 is a flow chart showing a method for automatically controlling the inhalation oxygen concentration of the ventilator according to an embodiment of the present invention, Figure 2 is an automatic inhalation oxygen concentration of the ventilator according to an embodiment of the present invention It is a schematic diagram which shows a control process.

The present invention compares the SpO2 measurement value measured in the patient and the SpO2 set value set as the target to automatically determine the concentration of FiO2 within the range prescribed by the doctor in accordance with the situation by supplying the patient to the discomfort of patients such as hypoxia It can be prevented. In particular, it is possible to reliably cure even during the sleep of the ward patient is not easy to access nursing. In addition, the present invention can be applied to low-pressure oxygen therapy, hyperbaric oxygen therapy and positive pressure ventilation performed using a nose mask or a mouthpiece without tracheal intubation or tracheostomy.

Prior to describing the automatic control of the inhalation oxygen concentration of the ventilator of the present invention, the ventilator to which the present invention is applied is subjected to a pressurized gas under an operator input schedule of predetermined conditions and gas composition, pressure, and flow pattern. It works by either pushing into the lungs and expanding the patient's chest space.

In other words, oxygen therapy ventilator is oxygen and air is introduced into the ventilator through the filter and valve, mixed with the proportional solenoid at the specified ratio, and then converted to the specified humidity and temperature through the bacterial filter and humidifier and supplied to the patient. At this time, the supply flow rate and oxygen content are designated by the microprocessor, and in order to supply the specified value to the patient, the microprocessor adjusts the required amount and ratio by appropriately opening and closing valves and regulators in each part. In addition, the sensor in each part converts the amount of gas measured in that part into an electrical signal and sends it to the microprocessor to control various valves and regulators. The respirator then monitors the biosignal supplied from the patient's condition and converts the monitored biosignal into an electrical signal through an analog-to-digital converter and provides it to the microprocessor.

1 is a flow chart showing a method for automatically controlling the inhalation oxygen concentration of the ventilator according to an embodiment of the present invention. Referring to FIG. 1, the automatic control method of the inhalation oxygen concentration of the ventilator of the present invention will be described. First, a step (S-10) of setting the SpO2 target value for the patient to the microprocessor provided in the ventilator is necessary. Do. SpO2 target value of the patient input in step S-10 is a target SpO2 value through the oxygen treatment of the patient, it is usually preferably set in the range of 80 ~ 96%.

In addition, in step S-10, it is preferable to input a FiO2 set value and an oxygen supply (FiO2 is not correct?) Upper and lower limits. As described later, the FiO2 set point causes the ventilator to supply oxygen by the FiO2 set point input in step S-10 when the patient's SpO2 value measured in step S-30 is not valid. do. In addition, the control value of FiO2, which is determined later to supply oxygen to the patient, is controlled within the upper and lower limits of the FiO2.

According to another embodiment of the present invention, in step S-10, it is also possible to input the type of patient, ie, whether the patient to be treated with oxygen is an adult or a child or an infant.

After the setting of the SpO2 target value is completed in the microprocessor of the ventilator as described above, the SpO2 of the patient is measured through a sensor such as a pulse oximeter (step S-20).

As described above, the SpO2 measurement value of the patient measured by the pulse oximeter or the like is converted into an electrical signal through an analog-to-digital converter and transmitted to the microprocessor. The SpO2 measurements sent as above are received at the microprocessor, and the SpO2 measurements of the patient received thereafter are stored at the microprocessor.

The pulse oximeter is a device used to measure SpO2 or pulse rate of arterial blood hemoglobin in home care patients as well as a professional medical institution.

The microprocessor that stores the patient's SpO2 measurements then validates the patient's SpO2 measurements (step S-30). The SpO 2 measurement value is a patient's essential measurement in the present invention because the reliability of the measurement value is reduced when there is a blood circulation disorder such as severe hypothermia, anemia, peripheral blood vessel contraction, and when there is strong light around the patient or when the patient moves. It is desirable to validate the SpO2 measurement of.

Hereinafter, a method of validating the SpO2 measurement value will be described.

Generally, since the SpO2 value of a normal person ranges from 80 to 96%, the effectiveness of the SpO2 measurement value of the patient can be determined by comparing the SpO2 value of the patient measured as described above with the SpO2 value of the normal person. Can be. That is, if the SpO2 measurement value of the patient is in the range of 80 to 96%, the SpO2 measurement value of the patient is determined to be valid, and conversely, if the measurement value of SpO2 of the patient is out of the range, it is determined to be an invalid measurement value. (Step S-30).

If it is determined in step S-30 that the patient's SpO2 measurement is valid, the patient's SpO2 measurement is then compared with the SpO2 target value input to the microprocessor in step S-10 (step S-40). ). In step S-40, the SpO2 measurement value of the patient is higher or lower than the SpO2 target value input to the microprocessor by comparing the SpO2 measurement value of the patient with the SpO2 target value input to the microprocessor. Judge in preparation.

As a result of the determination in step S-40, when the SpO2 measurement value of the patient is higher than the target value of SpO2 input to the microprocessor, the oxygen concentration of the FiO2 control value supplied from the ventilator is reduced. Conversely, if the SpO2 reading is lower than the SpO2 target input to the microprocessor, the oxygen concentration of the FiO2 control value supplied by the ventilator is increased.

As described above, after determining the SpO2 measurement value of the patient and the SpO2 target value input to the microprocessor in step S-40, the type of patient is determined to set the FiO2 control value (step S-50).

That is, the respiratory rate of the patient may be measured by using a respiratory sensor that is separately provided in the microprocessor of the respirator, and the type of the patient may be determined from the measured respiratory rate.

In general, respiratory rate is small in adults, and many children and infants. Adults have 15 to 20 breaths per minute, children have 40 breaths per minute, and infants have 20 to 30 breaths. Therefore, by measuring the respiratory rate of the patient using a breathing sensor, it is possible to determine whether the type of patient, that is, whether the patient is an adult or infants, children.

According to another embodiment of the present invention, it is also possible to input the type of patient when the SpO2 target value is input in step S-10.

If the type of the patient is determined in step S-50 or the type of the patient is input in step S-10, the FiO2 control value supplied from the ventilator is determined accordingly (step S-60).

The FiO2 control value set in step S-60 is determined within the range of the FiO2 upper limit value and the lower limit value. That is, the upper limit of FiO2 determined in step S-60 is set in the range of 25 to 100%, and the lower limit is set in the range of 21 to 96%. In addition, the upper limit value and the lower limit value of the FiO 2 control value may be set to maintain a difference of at least 4%. That is, when the upper limit value of the FiO2 control value is changed, the lower limit value is set to a value smaller than the upper limit value, but preferably set to be within a range satisfying the following equation.

At this time, the microprocessor determines the FiO2 control value supplied to the patient from the ventilator by comparing the SpO2 measurement value of the patient with the input SpO2 target value, and then supplies oxygen according to the determined FiO2 control value through the ventilator ( S-80 step).

If the SpO2 measurement value of the patient is not determined to be valid in the step S-30, the oxygen supply concentration is determined based on the FiO2 set value input in the step S-10 (step S-70). In other words, when the patient has severe hypothermia, anemia, or a blood circulation disorder such as peripheral blood vessel contraction, the SpO2 measurement value of the patient may not be valid. Also, when there is a strong light around the patient's SpO2 measurement or the patient moves during the measurement, the reliability of the SpO2 measurement value is reduced. Therefore, if the SpO2 measurement value of the patient is not valid, oxygen is supplied from the ventilator based on the FiO2 set value input in step S-10 as described above (step S-80). At this time, according to one embodiment of the present invention, the FiO2 setting value is preferably 60%.

In the method for controlling the intake oxygen concentration of the ventilator according to an embodiment of the present invention, the period of reflecting SpO2 in a patient is reflected in a period of 30 seconds for an adult and 15 seconds for a child and an infant. That is, in the case of adults, the SpO2 measurement value of the patient is reflected in the control every 30 seconds, and the concentration of oxygen is increased or decreased by 0.2% of the FiO2 supplied from the ventilator by contrast with the preset SpO2 target value. Will be supplied.

In addition, in the case of children and infants, SpO2 is measured and reflected to the control every 15 seconds, and the concentration of oxygen is increased or decreased by 0.2% of FiO2 supplied from the ventilator by contrast with the set SpO2 target value. desirable.

The FiO 2 control value set as described above is transmitted to the microprocessor of the ventilator to change the FiO 2 supplied to the patient to supply air mixed with oxygen at a predetermined ratio.

If the patient's SpO2 measurement and the input SpO2 target are the same through oxygen therapy of the ventilator, the FiO2 control value supplied to the patient is maintained.

Through the above series of procedures, the patient's SpO2 readings are automatically controlled based on the patient's SpO2 readings, thereby continuously monitoring the patient's SpO2 readings and manually controlling the ventilator according to the monitoring results. Since the sequence of steps is eliminated, the convenience to the ventilator can be further improved. In addition, it is possible to accurately calculate the amount of oxygen supplied to the patient, thereby eliminating the risk of exposure to oxygen (O ₂ ) toxicity and pulmonary disorders and hypoxia that may occur when incorrect oxygen is supplied.

Hereinafter, with reference to Figure 2 will be described in detail with respect to the automatic control method of the inhalation oxygen concentration of the ventilator of the present invention. 2 is a graph showing the results of oxygen treatment for an adult patient by the automatic control method of the inhalation oxygen concentration of the ventilator of the present invention.

In FIG. 2, the SpO 2 target value was set to 95%, the upper limit of FiO 2 was 65%, and the lower limit of FiO 2 was set to 40%. In addition, if the patient's SpO2 measurement was not valid, the FiO2 setpoint supplied to the patient was set to 60%. By comparing the SpO2 measurement value and the SpO2 target value of the patient from the setting conditions as described above, it is possible to minimize the damage of the patient due to incorrect supply of oxygen by automatically setting the FiO2 control value in real time and supplying it to the patient.

That is, section A in FIG. 2 is a section in which the SpO2 measurement value (orange line) is lower than the SpO2 target value (black dotted line), and is supplied to the patient through the comparison between the SpO2 measurement value and the SpO2 target value in the microprocessor of the ventilator. The FiO 2 control value, which is the intake oxygen concentration, is raised within the range between the FiO 2 upper limit (red line) and the lower limit (blue line) (green line). At this time, the SpO2 measurement value is measured every 30 seconds, and the FiO2 control value is determined by comparing with the SpO2 target value. According to the FiO2 control value, the ventilator supplies oxygen, and the concentration of oxygen supplied from the ventilator increases by 0.2% so that the SpO2 measurement value approaches the SpO2 target value.

Section B is a section in which the SpO2 measurement value is higher than the SpO2 target value, and is a section in which the microprocessor of the ventilator lowers the FiO2 control value, which is the intake oxygen concentration supplied to the patient by comparing the SpO2 measurement value with the SpO2 target value. As described above, the respirator supplies oxygen according to the FiO2 control value, and the concentration of oxygen supplied from the respirator decreases in units of 0.2% to bring the SpO2 measurement value closer to the SpO2 target value.

As shown in FIG. 2, when the SpO2 is not measured due to a problem in measuring SpO2 in the middle, when the SpO2 of the patient is not measured as described above, the FiO2 set value preset by the microprocessor ( Red dashed line), ie 60% of the oxygen supply to the patient.

In addition, section D is a section in which the SpO2 measurement value is close to the SpO2 target value and is maintained without changing the FiO2 control value.

The present invention provides a method for automatically controlling the inhalation oxygen concentration of the respirator by measuring the SpO2 measurement value of the patient from a sensor such as a pulse oximeter mounted on the patient as described above and supplying the patient in contrast to the SpO2 measurement value and the SpO2 target value By automatically determining and supplying FiO2 control values, oxygen therapy is provided to patients. Also, if the patient's SpO2 cannot be measured, oxygen is supplied based on the preset FiO2 set value, and if the patient's SpO2 measured value and SpO2 target value are similar, the FiO2 control value remains unchanged. do.

Through the automatic control of the inspiratory oxygen concentration of the ventilator as described above, appropriate oxygen treatment is performed to the patient to prevent oxygen toxicity and hypoxia due to incorrect supply of oxygen, and also to control the parameters of the respirator individually. It has the effect of eliminating the discomfort of medical staff.

Although the present invention has been described with reference to the experimental examples shown in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent other experimental examples are possible therefrom. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (8)

In the method of controlling the intake oxygen concentration of the ventilator,
Inputting a target value of blood oxygen saturation degree and a set value of intake oxygen concentration (S-10);
Measuring the level of oxygen saturation in the patient (S-20);
Verifying the effectiveness of the measured blood oxygen saturation degree (S-30);
Comparing the target value of the blood oxygen saturation degree with the blood oxygen saturation measurement value (S-40);
Determining the type of the patient (S-50);
Determining an inspiratory oxygen concentration control value supplied to the patient through steps S-40 and S-50 (S-60); And
Supplying oxygen according to the intake oxygen concentration control value (S-80);
Method of controlling the intake oxygen concentration of the respirator comprising a.
The method according to claim 1,
The target value of the blood oxygen saturation degree is 80 ~ 96% control method of the inhalation oxygen concentration of the ventilator.
The method according to claim 1,
The lower limit of the intake oxygen concentration is 21 to 96%, the upper limit is 25 to 100% control method of the inhalation oxygen concentration of the ventilator characterized in that.
The method according to claim 3,
And a lower limit and an upper limit of the intake oxygen concentration satisfy the following relational expression.

The method according to claim 1,
In the step S-20, the adult is measured at 30-second intervals and reflected in the control, the child is measured at 15-second intervals to control the inhalation oxygen concentration of the ventilator, characterized in that the control.
The method according to claim 1.
And a control value of the inspiratory oxygen concentration of the ventilator, wherein the control value of the inhalation oxygen concentration is determined by comparing the blood oxygen saturation target value and the blood oxygen saturation target value.
The method according to claim 1,
If the blood oxygen saturation level measured in step S-20 is not valid, oxygen is supplied to the preset intake oxygen concentration set value, characterized in that for controlling the intake oxygen concentration of the ventilator.
The method according to claim 7,
The preset intake oxygen concentration setting value is a control method of the inhalation oxygen concentration of the ventilator, characterized in that 60%.

Images