Respirator and method of controlling the same

Abstract

This invention relates to a ventilator, comprising a breathing tube connector for connecting a breathing tube; an actuator pneumatically connected to the breathing tube connector for delivering air to a patient via the breathing tube connector; a breathing sensor connector for providing breathing sensor signals; and a controller. The controller calculates the inhaled volume based on the breathing signals and calculates the inhaled volume and exhaled volume based on lung volume signals for each breath. The controller is also configured to determine when the exhaled volume exceeds an adjustable value relative to the inhaled volume, increasing the pressure at the end of exhalation. When oxygen saturation drops below a lower limit, the pressure at the end of exhalation is increased. If oxygen saturation drops below a lower limit, standby ventilation is initiated at a predetermined frequency. When oxygen saturation exceeds the lower limit again, the standby ventilation frequency is reduced. In another embodiment, standby ventilation is terminated when oxygen saturation exceeds an average limit. The invention also relates to a corresponding control method.

Description

[0001] This application was filed on March 10, 2016, with application number 2016800163186, and the invention title is "Respirator". This is a divisional application of the patent application for "and its control method", which was filed on June 16, 2020, with application number […]. 2020105488869, a divisional application entitled "Respirator and Control Method Thereof". Technical Field

[0002] The scope of the invention includes respirators of the type mentioned in the preambles of claims 1, 3, 5 and 7, and control methods of the type mentioned in the preambles of claims 10, 12 and 15.

[0003] EP 2091429 B1 discloses a respirator according to the preamble of claims 1 and 9.

[0004] This invention relates to the field of respirators and their control methods, and particularly to a respirator that takes into account the measurement of oxygen saturation in the blood by means of a pulse oximeter. Background Technology

[0005] It is well known that mechanically ventilated ventilators can cause various forms of oxygen deficiency. (Roche LexikonMedizin, 4) th (ed., Urban & Fischer Verlag, Munich). This type of respirator is also called a ventilator. There are three basic types:

[0006] a) Pressure-controlled respirator: The inspiratory phase terminates when the device reaches a predetermined breathing pressure. Exhalation is mostly passive.

[0007] b) Volume-controlled respirator: Inhalation terminates when the preset gas volume has left the respirator. Exhalation is mostly passive.

[0008] c) Time-controlled respirator: delivers a gas mixture within a preset time period.

[0009] Newer ventilators have electronic controls that allow for patient-compatible ventilation types. These ventilators typically include a pressure sensor that allows for the measurement of respiratory pressure. The pressure sensor can be located within the ventilator to measure the pressure at the ventilator end of the breathing tube.

[0010] In addition, most electronically controlled respirators can also have a flow sensor for measuring tidal flow rate. This refers to the amount of air inhaled or exhaled per unit time. This type of flow sensor is also called a spirometer. The inspiratory and / or expiratory volume is obtained by summing the flow values ​​returned by the flow sensor during the inhalation or exhalation phases. A more precise mathematical expression is achieved through tidal airflow. The inspiratory volume or expiratory volume is obtained by integrating the inhalation or exhalation.

[0011] EP 2091429B1 discloses an apparatus for determining PEEP (positive end expiratory pressure). It features a flow / pressure sensor capable of measuring both pressure and volume. This sensor is positioned, for example, on the breathing tube on the patient's side or integrated into the device. The patient is ventilated via the breathing tube through a ventilator. Comparing the respiratory volume V with the respiratory pressure p results in a so-called P / V curve that will exhibit hysteresis. A lower, rising branch, Vinf (inf represents inflation), is plotted when the lungs are inflated (inhalation). A higher, falling branch, Vdef (def represents ventilation), is plotted when air is expelled from the lungs (expiration). The appropriate PEEP can be seen in the curve. The appropriate PEEP is the pressure at which the maximum volume difference between Vdef and Vinf is measured. Because the inspiratory and expiratory volumes are the same in EP 2091429B1, the branches Vinf and Vdef intersect at the upper right and lower left, forming a closed P / V curve, meaning that an EFE (exhaled exhalation) event cannot occur in EP 2091429B1 (see below).

[0012] US2012 / 0071729A1 discloses a standard ventilator for human patients. The ventilator includes a pneumatic system for generating pressure and is connected to the patient via a tubing system and physical interfaces. The ventilator also includes a controller and a pulse oximeter. Various alarms can be triggered. An alarm can be triggered if SpO2, PEEP, or FiO2 exceeds or falls below a predetermined threshold. Another alarm is triggered if the operator has reduced PEEP before SpO2 falls below the threshold. A third alarm is triggered if FiO2 has been reduced before SpO2 falls below the threshold. US2012 / 0071729A1 does not disclose that PEEP can be modified, specifically increased when SpO2 falls below the threshold.

[0013] Once the airflow rate is known, the pressure drop of the breathing tube (see EP 1562655B1) and / or any existing endotracheal tube or endotracheal cannula can be calculated. Of course, the pressure drop at the partial breathing tube and / or endotracheal tube or endotracheal cannula can also be calculated. Therefore, any point between the ventilator and the lungs can be chosen for pressure control. Choosing oral pressure seems sensible, as it is most similar to lung pressure. In recent ventilators, the available ventilation modes are typically combinations of the three basic types described above.

[0014] CPAP (Continuous Positive Airway Pressure) ventilation is a form of ventilation that combines a patient's spontaneous breathing with a continuous overpressure, typically between 5 and 30 mbar. The patient can determine their own respiratory depth, respiratory rate, and tidal volume. EP 1294428B1 discloses by way of example how to detect breathing under CPAP.

[0015] Intermittent positive pressure ventilation (IPPV) is used in intensive care and emergency medicine. It is an abbreviation for volume-controlled ventilation with a ventilator. A commonly used synonym for IPPV is VCV, which stands for volume-controlled ventilation. In volume-controlled ventilation, the ventilator attempts to maintain a constant volume and respond to respiratory pressure. In this type of breathing, the air pressure in the expiratory tract may drop as low as 0 mbar at the end of expiration, but will not reach a negative value.

[0016] Today, pressure-controlled ventilation is used more frequently. It specifies two different pressure levels: one for inhalation and another for exhalation. This form of ventilation is also known as Bilevel or BIPAP (dual-channel positive pressure ventilation). In BIPAP, positive pressure (PEEP: positive end-expiratory pressure) is also present in the airway at the end of exhalation.

[0017] According to Rathgeber, Grundlagen der maschinellen Beatmung (Principles of Mechanical Ventilation), ISBN 9783131487926, 2010, Georg Thieme Verlag KG, all ventilation parameters are specified for volume-controlled ventilation. The target and control parameter is tidal volume. The resulting tidal pressure depends on the volume adjustment and the patient's lung condition. The patient cannot influence the inspiratory ventilation pattern. Typically, four parameters can be specified for volume-controlled ventilation: the magnitude of the inspiratory flow rate, the minimum minute ventilation, the ventilation rate, and the pressure at the end of expiration (PEEP). After opening the inspiratory valve, a constant flow rate of a defined amplitude is delivered until the end of the inspiratory phase. Other flow patterns, such as deceleration, acceleration, and sinusoidal flow, are no longer practically used for volume-controlled ventilation because they do not provide any conceivable benefit. The initial setting of the minimum minute ventilation and the inspiratory flow rate are based on the patient's weight, with newborns receiving approximately 250 ml of tidal volume per kilogram of body weight per minute. For newborns, the initial ventilation rate is set to approximately 50 breaths per minute.

[0018] IPPV is mainly used in the rescue service sector because the vehicles provided there can only use emergency respirators and usually do not support other forms of ventilation.

[0019] S-IPPV (Synchronized Intermittent Positive Pressure Ventilation) is a synchronized IPPV. In this case, the patient's inspiration can be identified and synchronized ("trigger"). Additionally, there is SNIPPV for breathing masks, nasal goggles, or similar patient interfaces without endotracheal intubation or tubing, where N stands for non-invasive.

[0020] PAV (Proportional Assisted Ventilation) is a ventilation mode in which the ventilator takes over a portion of the workload required for breathing. The ventilator adjusts tidal volume and pressure according to the patient's breathing activity. The deeper the patient's breathing, the higher the tidal volume and pressure delivered by the ventilator.

[0021] In premature infants, respiratory activity is reflexively regulated when oxygen saturation is too low. In existing techniques for ventilation of patients with respiratory distress, steps are described to monitor blood oxygen saturation (SpO2) by altering the oxygen concentration of the tidal FiO2 supplied to the patient. For example, this method is described in Yao et al.'s 1994 AAAI Technical Report SS-94-01, "Initiating an Emerging Workstation for Oxygen Control and Clinical Monitoring." A similar method is disclosed in WO 02 / 47741A2.

[0022] In Susanne Herber-Jonat et al.'s "Adaptive Mechanical Standby Ventilation in Preterm Infants in Assisted Breathing Modes" (2006, Intensive Care Med 32:302-308, Springer), a method of supplementing forced ventilation (mechanical standby) with PAV was described in cases of apnea, i.e., respiratory arrest or shallow breathing. For this purpose, (1) the physician could set the time interval between the end of respiratory activity and the automatic initiation of forced ventilation. (2) During the recovery of spontaneous breathing, forced ventilation was gradually reduced by decreasing the frequency of forced ventilation. (3) If the blood oxygen saturation SpO2 exceeded a user-defined threshold, spontaneous breathing without forced ventilation was permitted only under CPAP or PAV. This mode of forced ventilation is called SpO2-sensitive adaptive forced ventilation (SpO2-sensitive adaptive standby), and it has been clinically proven to improve treatment by gradually reducing standby. Furthermore, the goal of treatment is to maintain as little assistance as possible, as any form of ventilation carries potential risks.

[0023] EP 2671509A1 discloses a ventilation system in which a patient's respiratory activity is detected by a respiratory sensor element. The sensor element comprises a sensor component directly connected to the skin on the side of the patient's abdomen and a cable portion through which signals generated by the sensor component are transmitted to a data interface of the ventilation system's electronic equipment. The generated signal is calibrated by forming an arithmetic mean relative to previously generated signals. In cases where such computational calibration is not possible, the ventilation system includes means for calibrating the sensor element that interacts with the patient. The calibration means includes mechanisms for actuating valve elements for inflating and / or deflating the ventilation system. Summary of the Invention

[0024] One object of the present invention is to provide a ventilator and a method for controlling it with low risk of lung damage.

[0025] This goal is achieved through the theory of independent claims.

[0026] Preferred embodiments of the present invention are the subject of the dependent claims.

[0027]

[0028]

[0029] Table 1: Abbreviations Attached Figure Description

[0030] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Note:

[0031] Figure 1 A ventilation system according to the present invention is shown;

[0032] Figure 2 An optional control loop for controlling the oxygen content in the air is shown;

[0033] Figure 3 A flowchart of invasive ventilation control according to the present invention is shown; and

[0034] Figures 4 to 6 A flowchart of the non-invasive ventilation control according to the present invention is shown. Detailed Implementation

[0035] Figure 1 A respirator 1 according to the invention is shown, in which a newborn or pediatric patient 2 is ventilated via an endotracheal tube 3. A breathing mask can also be used as an alternative to the endotracheal tube 3. Figure 1 and Figure 2 As shown, electrical wires are represented by single lines and pneumatic wires by double lines. Ventilation is achieved through two breathing tubes 4 and 5, where fresh air for inhalation is supplied to the premature infant 2 via breathing tube 4, and exhaled air is expelled via breathing tube 5. This prevents carbon dioxide from accumulating in the breathing tubes.

[0036] If the respirator 1 is used in an intensive care unit, it is typically connected to a hospital gas supply, for example, represented by an oxygen cylinder 12 and a gas cartridge 15. However, the gas cylinder can also be physically present and placed outside the respirator, or, if properly designed, inside the respirator. The oxygen cylinder 12 is connected to connector 11 and the gas cylinder 15 is connected to connector 14. Intensive care respirators typically provide medical-grade oxygen via connector 11 and medical compressed air via connector 14. Air is passed from connector 14 to connector 29 via proportional valve 13. As a supplement to or alternative to cylinder 15 and connector 14, fresh air can be drawn in through opening 9 of the respirator 1 by blower 8 and blown into the breathing tube 4 above valve 7 via connector 29. The air from cylinder 15 or the hospital air supply is sterile. This makes it more difficult to ensure the quality of the ambient air drawn in through opening 9. Oxygen cylinder 12 is optional. It is used to increase the oxygen content in tidal FiO2. Oxygen is supplied to the breathing tube 4 via connector 11 and to the proportional valve 10 via connector 29. The oxygen content in the oxygen cylinder 12 is typically higher than 21% and can be as high as nearly 100%.

[0037] In other embodiments, the blower 8 and valve 7 may be replaced by proportional valves (i.e., inhalation valve and exhalation valve) before sensors 34 and 35, respectively.

[0038] Proportional valves 10, 13, and 6, valve 7, and blower 8, or alternative proportional valves, are electrically connected to and regulated by controller 16. By adjusting the speed of blower 8 or the opening width of the inspiratory valve and the positions of valves 6, 7, 10, and 13, fresh air is ensured to be supplied to the preterm infant 2 through breathing tube 4 during the inspiratory phase, and exhaled air through breathing tube 5 is expelled during the expiratory phase.

[0039] To ensure that ventilator 1 provides optimal support to the preterm infant 2 through its respiratory activity, ventilator 1 must recognize the preterm infant 2's spontaneous breathing and ensure ventilation meets the patient's needs without causing over- or under-ventilation. Since both the preterm infant 2 and the newborn are referred to as "gastric respirators," it is advantageous to detect respiratory activity via sensors attached to the abdomen, such as Graseby capsule 17, as disclosed in EP 2671509A1. Pressure in Graseby capsule 17 is transmitted via tubing 18 to connector 19 of ventilator 1. Pressure on connector 19 is converted into an electrical signal by pressure sensor 21, which is fed to controller 16 and may be referred to as a respiratory signal. Controller 16 calibrates Graseby capsule 17 periodically, for example, once every 10 breaths, during which the offset is specifically recalculated. If the offset value is too high, air can be supplied from Graseby capsule 17 to the outside via valve 33, or air can flow from the outside into Graseby capsule 17 via valve 33. During normal operation, valve 33 is closed. Compression of the Graseby capsule 17 results in an increase in pressure detected by pressure sensor 21. The capsule is filled with foam material to release it upon exhalation (e.g., exhalation). Valve 33 is electrically connected to and controlled by controller 16.

[0040] The pressure in the Graseby capsule 17 and the electrical signal transmitted by the pressure sensor 21 increase monotonically and nearly linearly with lung volume. The nonlinear element should be the Graseby capsule 17 itself. The inspiratory volume during respiration is obtained by multiplying a calibration factor by the difference between the maximum pressure at the end of exhalation and the minimum pressure at the beginning of exhalation. The expiratory volume during respiration is obtained by multiplying a calibration factor by the difference between the minimum pressure at the end of exhalation and the maximum pressure at the beginning of exhalation. It is not necessary to determine the calibration factor, as the controller according to the invention is based solely on the quotient of the expiratory and inspiratory volumes. In this respect, the difference between the pressure in the Graseby capsule 17 at time t and the minimum pressure during the corresponding respiratory phase can be referred to as the lung volume signal at time t.

[0041] It can also be achieved through inhaled and exhaled moisture. The lung volume signal is determined by provided flow sensors 35 and 34. These flow sensors 35 and 34 are electrically connected to controller 16 to provide the same flow rate as measured. Alternatively or additionally, a flow sensor located near the patient may also be located at patient connector 37, which is electrically or pneumatically connected to controller 16 via connector 38 and measures flow rate in the correct direction. The signal from flow sensor 34 is subtracted from the signal from flow sensor 35 to calculate the air in the trachea and mouth of the preterm infant 2. Airflow toward the preterm infant 2 is positive, and airflow away from the preterm infant is negative. The air entering the trachea and mouth of the preterm infant 2 can also be considered a respiratory signal. To determine the inspiratory and expiratory volume of airflow entering the mouth during respiration, individual measurements of the total flow rate during the inspiratory or expiratory phase must be summarized. To obtain the lung volume signal at time t from the total flow rate, all total flow rate values ​​from time t0 to time t are measured. t0 is added and placed at the beginning of the inspiratory phase.

[0042] If the sum of flow rates is monitored during the inspiratory phase, the inspiratory phase can be terminated when the total reaches a threshold (e.g., 0.5 liters), thus ensuring a certain inspiratory volume. In fact, the flow rate is initially generated in the controller as an integer value not calibrated in l / s. To save computation time, considering sampling rates from 100 Hz to 1 kHz, it is useful to convert the threshold in l into an integer limit for the sum of flow rates.

[0043] Finally, two pressure sensors 31 and 32 can optionally be provided to measure the air pressure near connectors 29 and 30, respectively. The airflow measured by flow sensors 34 and 35 can be used to calculate the total air pressure in breathing tubes 4 and 5 and endotracheal tube 3. Alternatively, the pressure sensors can detect the pressure at the patient connector 37.

[0044] The fact that the controller 16 can use the pulse oximeter 22 to measure the oxygen saturation SpO2 in the blood of the premature infant 2 is also important for control. The pulse oximeter 22 is electrically connected to the controller 16 via connector 23 and cable.

[0045] The respirator 1 ultimately includes a user interface with an input system 24, such as a keypad for inputting ventilation parameters, and a display 36 for displaying ventilation parameters and measurements. Both the input system 24 and the display 36 are electrically connected to the controller 16. Specifically, the user can input an upper limit SpO2 for oxygen saturation. 2O 25 and lower limit SpO 2U 27. Therefore, controller 16 calculates the arithmetic mean SpO, referred to as the saturation setpoint 26. 2M The saturation setting value 26 can be displayed. In another embodiment, the saturation setting value 26 can also be input by the user, thus displaying the value independently from the lower and upper limits of SpO. 2O25 and SpO 2U Choose from 27. Other ventilation parameters include, for example, the pressure PEEP 28 at the end of expiration, the end-expiratory pressure PEEP0, and the inspiratory flow rate, which are selected by the controller. Set ventilation frequency f B0 Ventilation frequency f B Minimum minute ventilation EFE event duration T E0 Stress factor p fr apnea duration t A and minimum retention time t B Optionally, the standard pressure can also be input at IP0 during inhalation.

[0046] The controller 16 may include a processor for executing software, random access memory, non-volatile memory, an analog-to-digital converter, a digital-to-analog converter, and power electronics. The precise electrical layout of the controller 16 can be designed by someone skilled in the art within the scope of their expertise.

[0047] Reference Figure 2 The block diagram illustrates an optional control loop used to control the oxygen content in the intake air. Figure 1 The proportioning valves 6, 10 and 13, flow sensors 35 and 34, breathing tubes 4 and 5, endotracheal tube 3, pulse oximeter 22 and connectors 23, 29 and 30 have been described. Figure 2 The controller 16 is shown in more detail below. Specifically, the controller 16 includes a PID controller 51, a subtractor 52, multipliers 53 and 54, and a respiratory control system 56. Although the PID controller 51, subtractor 52, and multipliers 53 and 54 are shown as devices, it will be apparent to those skilled in the art that these functions are implemented in the software of a modern controller. The PID controller 51 delivers a value between a minimum (e.g., 0) and a maximum (e.g., 1023) at its output. The subtractor 52 returns a second value that produces the maximum value when added to the PID controller. The PID controller value and the second value are multiplied by the inspiratory value 57 in multipliers 53 and 54, respectively. The results of multipliers 53 and 54 control proportional valves 13 and 10, respectively. Thus, the total inspiratory flow rate, which is substantially independent of the oxygen content FiO2, as measured by the flow sensor 31, can be set by the inspiratory value 57. Conversely, the control variable, namely the oxygen content FiO2, can be set to be largely independent of the inspiratory flow rate.

[0048] The target variable of the PID controller 51 is the saturation setpoint SpO. 2M 26, and fed to the PID controller 51 via the + / - input. The actual value of oxygen saturation SpO2 is fed to the - / - input of the PID controller.

[0049] During operation, premature infant 2 is part of a closed-loop control system. The relationship between oxygen content (FiO2) and oxygen saturation (SpO2) is non-linear. Therefore, for example, a set limit SpO2 is used. 2O 25 and SpO 2U 28. It is useful to modify the control parameters 55 of the PID controller 51 by varying the directional oxygen saturation SpO2, namely the gain factors of the proportional-integral and differential components. The relationship between oxygen content FiO2 and oxygen saturation SpO2 also depends on the condition of the preterm infant, i.e., whether he is asleep or awake. Therefore, other parameters such as tidal volume in PAV or oxygen saturation SpO2 itself can be considered.

[0050] Figure 3 A flowchart is shown illustrating key steps in a respiratory control system 56 with invasive ventilation featuring tidal volume monitoring (e.g., IPPV). In step 61, the inspiratory flow rate is set. Set the ventilation frequency fB to be equal to the set ventilation frequency f. B0 Set the pressure at the end of expiration (PEE pressure / PEEP) to be equal to the set pressure at the end of expiration (PEEP0). Optionally, the inspiratory pressure IP can also be set to the default value IP0. After each breath, perform... Figure 3 The steps shown are repeated once. Therefore, in step 62, wait for the breathing to end. Normally, breathing begins with inhalation and ends with exhalation. For the present invention, breathing may also begin with exhalation and end with inhalation. The criterion for termination of exhalation and inhalation is the form of ventilation, such as IPPV.

[0051] In step 63, the inspiratory volume V is determined. i and expiratory volume V e The "OK" button in step 63 only indicates that the value has been read. Specifically, in the case of IPPV, the minimum minute ventilation can be used. and ventilation frequency f B Calculate the set inspiratory volume. It is useful to add the individual tidal volumes measured during expiration to obtain the expiratory volume V at the end of expiration. e .

[0052] In Comparison 64, expiratory volume is compared to inspiratory volume. If the expiratory volume exceeds the inspiratory volume by at least 50%, i.e., V... e / V i If the value is ≥1.5, then the EFE event is stored in step 65, for example, by adding the current time t to a predetermined or adjustable EFE event duration t. ED To calculate the end time t E And store the end time t EIn another embodiment, the operator can set a threshold other than 50%. TED is at least one breath, and it makes sense for the user to set it to a longer duration. In Comparison 66, the duration t of the EFE event is examined. ED The order depends on comparison result 64, which is performed immediately after comparison 64 or step 65. In comparison 67, the duration t of the EFE event is considered. ED After an EFE event, check whether the measured oxygen saturation SpO2 is below the set lower limit SpO2. 2U If so, then in step 68, the pressure factor p is used. fr Increase PEEP, for example, by 10% preset by the user. Optionally, before or after step 77, or approximately simultaneously with step 77, this can be achieved via a factor p. i Increase the inspiratory pressure IP to maintain a constant amount of gas exchanged. Alternatively, the user can set a fixed pressure value that must be used to increase the PEE pressure. This also applies to the inspiratory pressure. The order of comparisons 66 and 67 can also be interchanged. The ventilation frequency f can be increased in step 69. B This is to maintain a constant amount of gas exchanged during the appropriate ventilation phase.

[0053] If comparison 66 or 67 returns "No", proceed to step 70. In contrast, check if the oxygen saturation SpO2 exceeds the saturation setpoint SpO2. 2M If this is not the case, wait for the next breath to finish in step 62. If the oxygen saturation SpO2 exceeds the saturation set point SpO2... 2M Then PEEP gradually resets to its original value, where it is reduced by the pressure factor p in each step. fl Segmentation. Pressure factor p fr and p fl They can be the same, but keep p. fl Below p fr This makes sense, as the reduction of PEEP is slower than the previous increase. One of these steps is shown in step 71. In step 78, when the inspiratory pressure IP has already increased in step 77, the inspiratory pressure IP is reduced in the same way, i.e., by dividing by p. i Or subtract the fixed pressure difference. In Comparison 72, check if PEEP is already lower than the set pressure at end-expiratory PEEP0. If so, set PEEP to PEEP0 in Setting 73. If the ventilation rate f during PEEP adaptation... B If it is also changed, the ventilation frequency fB0 is reset in settings 74 and 76 and the ventilation frequency f is set in comparison 75. B0It is similar. If the inspiratory pressure IP has increased in step 77, it is set to the default value IP0 in step 79.

[0054] After setting 69 or 76 or comparing 75, wait for the end of the next breath in step 62.

[0055] Figures 4 to 6 A control flowchart for non-invasive ventilation according to the present invention is shown, which has a set apnea duration t. A This refers to CPAP or SNIPPV. Here, ventilation intensity, particularly the ventilation frequency (f), is controlled by decreasing oxygen saturation. B Ventilation frequency f B There are five standby stages. The ventilation frequency of stage 1 is f. B It is the set ventilation frequency f B0 The ventilation frequency is reduced by two-thirds from one standby stage to another. The ventilation frequencies for stages 2 and 3 are f. B0 Two-thirds (approximately 66%) and f B0 Three-quarters (approximately 44%). At each level, there exists an adjustable minimum retention time t. B The minimum retention time is typically 30 seconds. In one embodiment, the minimum retention time can be selected from four values: 0s, 10s, 30s, or 60s. If this minimum retention time is set to 0, standby ventilation is terminated immediately if not necessary. A retention time set to 0 is called FCBU (Frequency Controlled Standby). Under SNIPPV, the ventilation frequency is not less than 4 / 9 of a second. B0 CPAP or nCPAP below, less than 16 / 81 (approximately 20%) B0 .

[0056] If in step 81, the duration of apnea is t A If no breathing is detected, indicating apnea, then in step 83, the variable BuBySpO2 is set to 0, and the reason for initiating standby ventilation is stored. In step 82, the ventilation frequency f is set in standby stage 1. B0 Standby ventilation is initiated. SNIPPV is used as standby ventilation. In step 84, the current time t and the minimum hold time t are... B The sum is calculated as t BE The earliest possible end. In step 87, wait for the minimum retention time to end.

[0057] If spontaneous breathing is detected in step 85, then in step 89 the maximum ventilation rate f will be set. B0Reduce its value in step 89 by one-third to approximately 66%, while simultaneously initiating FCBU (compare 86), i.e., continuing in standby stage 2. If spontaneous breathing is not detected in step 85, in steps 83 and 82, standby ventilation is maintained at a frequency f. B0 Continue at that point. Therefore, if t BE >0, the duration of the standby level is 1n*t BE , where n is an integer. If spontaneous breathing is detected in step 85, standby ventilation continues at level 2, and a new ventilation rate is calculated and set in step 89. When FCBU is activated, i.e., t B >0, in step 88, time t is recalculated based on comparison 86. BE In step 115, wait for the process to finish. If FCBU is not activated in comparison 86, and the oxygen saturation in comparison 94 is higher than the lower limit SpO2, then... 2U And since the apnea in step 81 initiates standby ventilation, i.e., BuBySpO2 == 0, the process jumps to terminate standby ventilation 117. As with many programming languages, && represents the logical AND operator, and == represents the comparison operator for checking equality.

[0058] Otherwise, in comparison 90, check whether the oxygen saturation SpO2 is higher than the oxygen saturation SpO2. 2U The lower limit, and spontaneous breathing is dominant. If this is the case, then in step 93 of standby level 3, the ventilation rate f is set. B0 4 / 9 of the ventilation frequency f B Continue standby ventilation. Then, calculate the minimum retention time t in step 91. BE At the end, and wait for the minimum retention time in step 92.

[0059] If the oxygen saturation SpO2 is lower than the oxygen saturation SpO 2U If the minimum retention time t is reached, spontaneous breathing is detected in step 85, and the FCBU is activated in step 86. Then, the minimum retention time t is restarted in step 88. B This is achieved by recalculating t at the end of step 88. BE (That is, to move to the future) to achieve.

[0060] In comparison 98, spontaneous respiration or oxygen saturation SpO2 below the limiting SpO2 was observed. 2U The existence of comparison 90 is the same as comparison 98. Like many programming languages, "||" represents the logical OR operator, and "!" represents NOT. If comparison 98 does not occur spontaneously or falls below the limit SpO... 2UIf no spontaneous breathing is detected in Comparison 85, then switch to Comparison 99. In contrast, Comparison 85 shows no spontaneous breathing and proceeds through steps 83 and 82 to Standby Stage 1. Under SNIPPV checked in Comparison 99, switch to the next Standby Stage 4 without changing the frequency. If Comparison 99 shows CPAP selected as the ventilation mode instead of SNIPPV, then Comparison 100 checks whether oxygen saturation has reached the saturation set point SpO2. 2M If this is not the case, control remains at standby level 3, and the calculation of the new earliest end t continues in step 91. BE .

[0061] If the oxygen saturation SpO2 in 100 reaches the saturation set value SpO 2M Then, it also switches to standby level 4 under CPAP, and calculates and sets the new standby frequency f in step 105. B =0.29×f B0 In level 4, and then in step 102, the new earliest terminal t is calculated. BE In step 101, wait for the end t BE In comparison 106, we re-examined whether spontaneous respiration occurred and whether oxygen saturation dropped to the limit SpO2. 2U If either of the two conditions is not met, then as mentioned before, return to comparison 85 after comparison 85.

[0062] If spontaneous respiration occurs in 106 cases, and the oxygen saturation SpO2 is at least equal to the limiting SpO2... 2U If SNIPPV is used as the ventilation mode in Comparison 107, switch it to Standby Stage 5 without changing the frequency. If the ventilation mode is not SNIPPV, then in Comparison 108, it is also necessary to check whether the oxygen saturation SpO2 has reached the saturation setpoint SpO2. 2M If this is not the case, the standby remains at standby level 4, where comparison 106 continues. If comparison 108 determines that oxygen saturation SpO2 has reached the saturation setpoint SpO2... 2M Then switch to standby stage 5 and in step 113 change the ventilation frequency f B Reduced to 0.19×f B0 Ignoring CPAP or SNIPPV, in step 110, the earliest end t of level 5 is calculated in standby level 5. BE And in step 109, we wait for the end. In comparison 114, we check, in turn, whether spontaneous respiration exists and whether oxygen saturation SpO2 is at least equal to the limiting SpO2. 2U If spontaneous respiration does not occur or oxygen saturation falls below the limiting SpO2 level. 2U Then proceed to step 85. If spontaneous respiration occurs and oxygen saturation is at least equal to the limiting SpO2 level...2U Then, the standby status is terminated in step 117.

[0063] If no apnea is detected in step 81, i.e. spontaneous breathing occurs or is obstructed for less than the duration t of the apnea. A If breathing apnea occurs, step 95 checks whether the oxygen saturation SpO2 is lower than the oxygen saturation SpO2. 2U The lower limit. If this is not the case, the breathing control system 56 can wait and then recheck for apnea in step 81. If the oxygen saturation SpO2 in comparison 95 is lower than the oxygen saturation SpO2, then... 2U If the lower limit is reached, standby ventilation begins. In step 96, the ventilation frequency f is set. B The set ventilation frequency f in standby stage 2 B0 Standby ventilation begins at 2 / 3 (approximately 66%). Prior to this, in step 97, the standby ventilation that has entered due to saturation drop (i.e., via step 95) is stored by setting the variable BuBySpO2 = 1 to prevent premature exit from comparison 94. In further steps, the sequence of process steps is the same as that of standby ventilation, which is caused by apnea in comparison 81.

[0064] Even in Figure 1 and Figure 2 It is not explicitly stated in the document. For example... Figures 4 to 6 As shown, the apnea detection in step 81 also occurs during standby ventilation. If apnea occurs in a higher standby level, a switch to standby level 1 is performed in steps 83 and 82. This can occur in standby level 3 and higher.

[0065] The present invention has been described in detail based on preferred embodiments. However, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. Therefore, the scope is defined by the appended claims and their equivalents.

[0066] Reference Number List

[0067] 1. Respirator

[0068] 2. Newborns or pediatric patients

[0069] 3. Endotracheal intubation

[0070] 4, 5, breathing tube

[0071] 6. Proportional valve

[0072] 7. Valves

[0073] 8. Blower

[0074] 9. Opening

[0075] 10. Proportional valve

[0076] 11. Connectors

[0077] 12. Oxygen cylinder

[0078] 13. Proportional valve

[0079] 14. Connectors

[0080] 15. Gas cylinders

[0081] 16. Controller

[0082] 17. Graseby capsules

[0083] 18. Pipe

[0084] 19. Connectors

[0085] 21. Pressure sensor

[0086] 22. Pulse Oximeter

[0087] 23. Connectors

[0088] 24. Input System

[0089] 25. Upper limit

[0090] 26. Saturation setpoint

[0091] 27. Lower limit

[0092] 28. PEEP

[0093] 29, 30, Connectors

[0094] 31, 32, Pressure Sensors

[0095] 33. Valve

[0096] 34, 35, Flow Sensor

[0097] 36. Monitor

[0098] 37. Patient connector

[0099] 38. Connectors

[0100] 51. PID controller

[0101] 52. Subtractor

[0102] 53, 54, Multipliers

[0103] 56. Respiratory Control System

[0104] 61–116, Steps.

Claims

1. A ventilator for ventilating a patient, comprising: Breathing tube connectors (29, 30) for connecting breathing tubes (4, 5); Actuators (8, 10, 13) pneumatically connected to breathing tube connectors (29, 30) are used to deliver air to the patient (2) via breathing tube connectors (29, 30). Pulse oximeter connector (23) for returning oxygen saturation signals; A controller (16) electrically connected to the pulse oximeter connector (23), the pulse oximeter connector (23) being used to feed the oxygen saturation signal to the controller (16), wherein the controller (16) is used to: - Calculate oxygen saturation based on the oxygen saturation signal. - Determine if the decrease in oxygen saturation (95) is below the lower limit (27), and if so, initiate standby ventilation (96) at a predetermined frequency. When the oxygen saturation exceeds the lower limit (27) again, reduce the frequency of standby ventilation (91). Its features are, The controller (16) is also used to reduce the frequency of standby ventilation when the oxygen saturation exceeds the saturation setpoint (26), the saturation setpoint (26) being greater than the lower limit (27).

2. The respirator of claim 1, wherein, The controller (16) is also used to terminate standby ventilation (117) when the oxygen saturation continues to exceed the saturation set value (26) (108) after the ventilation frequency (104, 105) is further reduced.

3. The respirator of claims 1 or 2, wherein, The respirator (1) further includes a valve (13) and an oxygen connection (14) for a gas mixture (15) with a gas or oxygen volume greater than 21%, wherein the inlet of the valve (13) is pneumatically connected to the oxygen connection (14), the outlet of the valve (13) is pneumatically connected to the breathing tube connection (29), and the control connection of the valve (13) is electrically connected to a controller (16), wherein the controller (16) further includes a PID controller (51) for controlling the valve (13) such that the oxygen saturation is as close as possible to the saturation setpoint between the upper limit (25) and the lower limit (27).

4. The respirator of claims 1 or 2, wherein, Further includes: A respiratory sensor connector (19) for respiratory sensors (17, 34, 35) for returning respiratory signals, wherein a controller (16) is electrically connected to the respiratory sensor connector (19), wherein the respiratory signals are fed to the controller (16), the controller being used to: - Calculate a lung volume signal based on the respiratory signal, wherein the lung volume signal increases monotonically with the lung volume of the patient (2), and wherein the controller (16) is used to calculate the inhaled volume and expiratory volume based on the lung volume signal for each breath; and When the exhaled volume exceeds the associated inhaled volume by an adjustable value (64), the controller (16) is also used to store (65) the EFE event and to increase (68) the pressure at the end of exhalation during the EFE event.

5. The respirator of claim 4, wherein, Also includes: A pulse oximeter connector (23) electrically connected to the controller (16) and used to return an oxygen saturation signal; wherein the controller (16) is further configured to calculate an oxygen saturation from the oxygen saturation signal to determine if the oxygen saturation is below (67) a lower limit (27) a certain time after an EFE event has occurred and to increase (68) the end expiratory pressure if the oxygen saturation is below the lower limit.

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