RU2665624C2 - Method of implementation of artificial lung ventilation and apparatus for artificial lung ventilation in which this method is implemented - Google Patents

Method of implementation of artificial lung ventilation and apparatus for artificial lung ventilation in which this method is implemented Download PDF

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RU2665624C2
RU2665624C2 RU2016140202A RU2016140202A RU2665624C2 RU 2665624 C2 RU2665624 C2 RU 2665624C2 RU 2016140202 A RU2016140202 A RU 2016140202A RU 2016140202 A RU2016140202 A RU 2016140202A RU 2665624 C2 RU2665624 C2 RU 2665624C2
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volume
respiratory
minute volume
ventilation
breathing
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RU2016140202A (en
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Юрий Владимирович Кофман
Анатолий Викторович Сергиенко
Алексей Владимирович Чистяков
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Общество с ограниченной ответственностью Фирма "Тритон-ЭлектроникС"
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    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61HPHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H31/00Artificial respiration or heart stimulation
    • A61H31/02"Iron-lungs", i.e. involving chest expansion by applying underpressure thereon, whether or not combined with gas breathing means

Abstract

FIELD: medicine.SUBSTANCE: group of inventions refers to the field of medicine, anesthesiology, resuscitation and intensive care. Determine the target respiratory minute volume on the basis of the ideal body weight and the specific coefficient of respiratory minute volume. Calculate the ratio of the respiratory rate and the respiratory volume corresponding to the minimum respiratory work. Then, the safe limits of respiration rate, respiratory volume, inspiratory and expiratory time are calculated, and the target respiratory minute volume is retained with a change in the respiratory rate in the calculated safe limits. In addition, the starting specific coefficient of the respiratory minute volume is additionally set. Moreover, the respiratory minute volume is automatically corrected within the preset range when the spontaneous respiration rate leaves the calculated dynamic range, but not less than the respiratory minute volume established with the starting factor of the respiratory minute volume. Apparatus for implementing the process, comprising a gas mixer, flow sensor, flow generator, the main line of inspiration and expiration, pressure sensors located in the highways of inspiration and expiration, the expiration valve and the flow sensor located at the expiration valve outlet, a ventilation controller electrically connected to a gas mixer, flow sensors, flow generator, expiration valve and pressure sensors, and an input and output device connected to the ventilation controller. In this case, the ventilation controller is configured to receive data from the flow and pressure sensors, calculate the parameters of the volume of inspiration, compliance and aerodynamic resistance, calculate the ratio of respiratory rate and respiratory volume, corresponding to the minimum respiratory work, calculate the safe limits of the respiration rate, the respiratory volume, the inspiration and expiration time, the retention of the target respiratory minute volume with a change in the respiratory rate in the calculated safe limits, adjusting the minute volume of respiration within a predetermined range when the spontaneous respiration rate leaves the calculated dynamic range by controlling the action on the flow generator and expiration valve.EFFECT: method and the device allow the artificial lung ventilation, provide a full cycle of patient ventilation, from fully hardware ventilation in conditions of deep anesthesia to weaning from the apparatus with stable spontaneous breathing, provide the necessary support for pressure for each of the phases, and for their combination with minimal operator intervention during the transition from one phase to another.17 cl, 1 dwg, 1 tbl

Description

The group of inventions relates to medicine, namely to medical equipment aimed at supporting the respiratory functions of the patient’s body, including delivery of anesthesia and respiratory assistance, and can be used in anesthesiology, intensive care and intensive care to replace the temporarily lost function of external respiration.

The technical solution according to the European patent for the invention "An apparatus for regulating a mechanical ventilation" is known (patent holder Hamilton Medical AG, z. No. 07701843.1 of January 30, 2007, IPC A61M 16/00). According to the description of the technical solution, the device comprises an air flow generating compressor with a gas mixing chamber, flow, pressure, inspiratory and expiratory flow sensors, an exhalation valve and a flow sensor located at the outlet of the exhalation valve, a control system associated with the compressor, flow sensors, exhalation valve and pressure sensors. The device may further comprise an information input and output device connected to the control system.

The design of the device according to the presented description does not allow the use of oxygen supplying devices to the system with minimal pressure as oxygen sources, for example, membrane oxygenators, since the value of the pressure in the system during inspiration is higher than the pressure under which such an oxygenator supplies oxygen.

The technical solution selected as the closest analogue for the proposed method is the method described in the articles Adaptive support ventilation (ASV) Brunner JX et al (Minerva Anestesiol, 2002; 68: 365-8) and Adaptive support ventilation User's Guide, Hamilton medical AG ( Switzerland, 1999). According to the text of the description, the method includes setting the target minute breathing volume (% MinVol,% MV), consisting of determining the ideal body weight (IBW), according to centile tables or a well-known formula, determining and setting the specific physiological coefficient of respiration (V e , target minute volume, L / min / kg). Then, automatically calculate the inspiratory volume (target tidal volume, VT) and respiratory rate (BH, respiratory rate, RR) corresponding to the minimum work of the respiratory system (minimum work of breathing, minWOB), according to the Otis formula (The Work of Breathing, Otis AB et al, Physiol Rev., 1954, PMID [13185751]). Next, the limiting parameters of the respiratory rate, inspiratory volume, inspiratory and expiratory time are calculated. If the respiratory rate reaches the lower calculated boundary, the inspiratory volume increases, but when the respiratory rate is high, then the resistance of the organs increases. ASV adjusts both parameters when the patient is breathing apparatus, if the patient begins to breathe spontaneously, ASV adjusts only the pressure on the inspiration, and thereby adjusts the VT.

The method described above is not fully suitable for patients who have some features of the functioning of the respiratory system. In particular, in conditions of hyper- or hypometabolism, the use of the method requires constant monitoring of the operating parameters of the device using this method, which significantly reduces the level of autonomy of the device.

The developed technical solutions allow us to overcome these shortcomings and create a method of adaptive artificial ventilation of the lungs and an apparatus in which this method is implemented.

The task to which the group of inventions is directed is to create a method and device that uses the created method to improve the quality of the artificial lung ventilation apparatus by adapting the functioning mode of the artificial lung ventilation apparatus to the individual characteristics of the patient’s body, including, changes in the patient's condition when replacing the function of external respiration.

The problem is solved in that the method of artificial ventilation of the lungs includes determining the target minute breathing volume based on the ideal body weight and specific coefficient of the minute breathing volume, calculating the ratio of the respiratory rate and tidal volume corresponding to the minimum respiratory work, calculating the safe boundaries of the respiratory rate, tidal volume , inspiratory time and expiratory time, and holding the target minute volume of breathing when changing the respiratory rate in the calculated safe gras nits, and the minute volume of respiration is automatically adjusted within a predetermined range when the frequency of spontaneous respiration exceeds the limits of the calculated dynamic range.

The similarity of the proposed method for the implementation of artificial ventilation of the lungs with the closest analogue is manifested in determining the target minute breathing volume based on the ideal body weight and specific coefficient of the minute breathing volume, calculating the ratio of the respiratory rate and tidal volume corresponding to the minimum respiratory work, calculating the safe boundaries of the respiratory rate, tidal volume , inspiratory time and expiratory time, and holding the target minute volume of respiration when changing the respiration rate in the calculated safe boundaries.

In the general case of implementation, the proposed method for the implementation of artificial ventilation of the lungs differs from the closest analogue in that the minute volume of respiration is automatically adjusted within a predetermined range when the spontaneous respiration rate goes beyond the calculated dynamic range.

In the second special case, this problem is additionally solved by the fact that the minute volume of breathing is automatically adjusted in the range from the specific coefficient of the minute volume affixed by the operator,%: up to 220.

In the third particular case of implementation, this task is additionally solved by the fact that the automatic adjustment of the minute volume of breathing is carried out depending on the frequency of spontaneous breathing.

In the fourth special case of implementation, this task is additionally solved by the fact that the upper limit of the adjustment of the minute volume of breathing is limited by the absolute value,%: 220.

In development of the second particular case of the implementation of the method of artificial ventilation of the lungs, this problem is additionally solved by the fact that the lower boundary of the minute volume of breathing is established on the basis of calculating the ideal body weight and selecting the specific coefficient of the minute volume of breathing;

In the fifth particular case of implementation, this task is additionally solved by the fact that the upper boundary of the tidal volume is determined by the formula:

Figure 00000001

Where:

V Tmax - the upper limit of the tidal volume;

P max - the upper limit of the safe pressure set by the operator;

PEEP - positive pressure at the end of exhalation;

C st - static compliance;

K v - maximum volume ratio (default 22)

IBW - ideal body weight;

V Tmin is the lower boundary of the tidal volume;

In the sixth particular case of implementation, this task is additionally solved by the fact that the lower boundary of the tidal volume is determined by the formula:

Figure 00000002

Where:

V Tmin is the lower boundary of the tidal volume;

V d is the estimated volume of dead space;

IBW - ideal body weight;

In the seventh special case of implementation, this task is additionally solved by the fact that the upper limit of the safety of the frequency of respiratory depression is determined by the formula:

Figure 00000003

Where:

RB max is the upper limit of the safe respiratory rate;

RC exp - expiratory constant;

RB min is the lower limit of the safe respiratory rate;

In the eighth particular case of implementation, this task is additionally solved by the fact that the lower limit of the safe frequency of respiratory depression is determined by the dependence:

Figure 00000004

Where:

RB min is the lower limit of the safe respiratory rate;

IBW - ideal body weight;

In the ninth special case of implementation, this task is additionally solved by the fact that the minimum expiration time is determined by full expiration (while the flow from the patient’s lungs is zero) or stabilization of the flow, but not more than Te max ,

Where:

Te max = 11 sec.

In the tenth special case of implementation, this task is additionally solved by the fact that the minimum inspiration time is determined by the formula:

Figure 00000005

Where:

Ti min - minimum inspiration time;

Ti P is the pressure build -up time;

Ti f - time to reduce the flow to a level determined by the program (usually zero - for a full breath)

Ti max = 3 ... 5 sec depending on the expiratory constant

In the eleventh special case of implementation, this task is additionally solved by the fact that the minute volume of respiration is automatically adjusted depending on the content of CO 2 in the output stream.

In the first refinement of the eleventh special case of implementation, this task is additionally solved by the fact that the adjustment of the minute volume of breathing is additionally carried out in accordance with the following algorithm: setting the upper and lower values of the range of CO 2 content in the output stream, measuring the real CO 2 content in the output stream, comparing the real CO 2 content in the exit stream from the upper value range predetermined CO 2 content, the comparison of the real content of CO 2 in the effluent to a lower predetermined value di pazona CO 2 content, the adjustment of the respiratory minute volume at an output real-CO 2 content beyond a certain range content of CO 2, the repetition cycle before entering the actual content in the exhaled CO 2 stream specified range of values of CO 2 in the exhaled flow.

In the second refinement of the eleventh particular case of implementation, this problem is additionally solved by the fact that the content of CO 2 in the exhalation fraction is determined by means of a capnograph.

In the third refinement of the eleventh particular case of implementation, this task is additionally solved by the fact that the rate of adjustment of the minute volume of breathing is 2% for each breath.

In the fourth refinement of the eleventh special case of implementation and in the development of the method in the general case of implementation, this task is additionally solved by using automatic adjustment of the minute volume of respiration according to one of the parameters: by the frequency of spontaneous respiration or by the CO 2 content in the exhaled stream.

The application of the proposed method is carried out by means of an artificial lung ventilation apparatus containing a gas mixer, a flow sensor, a flow generator, inhalation and exhalation lines, pressure sensors located in the inhalation and exhalation lines, an exhalation valve and a flow sensor located at the outlet of the exhalation valve, a ventilation controller, electrically connected to a gas mixer, flow sensors, a flow generator, an exhalation valve and pressure sensors and an information input and output device connected to a valve controller ii, and the ventilation controller receives data from flow and pressure sensors, calculates the inspiratory volume, suppleness and aerodynamic resistance parameters, calculates the ratio of the respiratory rate and tidal volume corresponding to the minimum respiratory work, calculates the safe boundaries of the respiratory rate, tidal volume, inspiratory time and expiratory time , holds the target minute volume of respiration when changing the respiration rate in the calculated safe boundaries, adjusting the minute volume of respiration within of the previously established range when the spontaneous respiration rate goes beyond the limits of the calculated dynamic range by controlling the flow generator and exhalation valve.

Signs similar to the selected closest counterpart are a gas mixer, a flow sensor, a flow generator, inhalation and exhalation lines, pressure sensors located in the inhalation and exhalation lines, an exhalation valve and a flow sensor located at the outlet of the exhalation valve, a ventilation controller electrically connected to a gas mixer, flow sensors, a flow generator, an exhalation valve and pressure sensors, and an information input and output device connected to a ventilation controller.

In the general case of execution, the claimed invention differs from the closest analogue in that the ventilation controller receives data from flow and pressure sensors, calculates inspiratory volume parameters, suppleness and aerodynamic resistance, calculates the ratio of the respiratory rate and tidal volume corresponding to the minimum respiratory work, calculates safe boundaries respiratory rate, tidal volume, inspiratory time and expiratory time, holds the target minute respiratory volume with a change in respiratory rate in calculated safe boundaries, adjusting the minute volume of respiration within a predetermined range when the spontaneous respiration rate goes beyond the calculated dynamic range by controlling the flow generator and exhalation valve.

In the particular case of the technical task, defined jointly for the method and device, is solved by the fact that the ventilation controller receives data from flow sensors and according to the formula:

F lungs = F inhale -F exhale ,

Where

F lungs - the flow of gas entering the patient’s lungs;

F inspiration - gas flow at the inlet (on the tee, taking into account the contour);

F exhalation is the gas flow at the outlet (on the tee, taking into account the circuit),

moreover, the ventilation controller uses the F light value to calculate the control action on the flow control devices and valves.

Determination of the minute volume of breathing allows you to set the required amount of the respiratory mixture, which should enter the patient's respiratory system. With the beginning of work (or when changing the parameters “gender”, “age”, “height”), ideal body weight (IBW) is calculated using the formulas that are standardly used in such cases to calculate IBW for an adult patient, and children’s IBWs are determined from the dental tables . After determining the ideal weight, a standard minute volume of breathing (MOD) is obtained, since lung volume is more correlated with growth than with real weight. If the MOD for this patient requires adjustment, then it is carried out by the operator, as a rule, through a change in% MV (MOD coefficient), but also, in some cases, the growth can be changed. In any phase of ventilation, the claimed method focuses on the implementation of the modifier coefficient specified by the operator.

The key criterion of the proposed method for respiratory depression is naturalness, expressed in the implementation of such a path of respiratory support, which would offer the body itself. According to the practice-confirmed Otis hypothesis (Otis A.B., see above), the most functional and organic is the breathing pattern in which the required tidal volume is extracted with minimal energy costs. Hence, the following principles are implemented in the method: full exhalation - the exhaust air should not remain in the lungs; full inhalation - do not start exhaling until the calories burned give the maximum respiratory effect, i.e. until the air flow at a given pressure (analogue of the muscular expansion of the lungs) is reduced to zero. Pressure with a full breath is obviously minimized; respiratory rate and inspiration depth should be selected so that the total work is minimal. To calculate the optimal ratio of frequency and volume A.V. Otis proposed a formula in which the respiratory rate is based on the required minute volume of air, lung volume, lung characteristics (compliance) and respiratory tract (resistance).

The method ensures the achievement of the lowest possible average pressure in the lungs, taking into account the patient’s respiratory specificity, by measuring the parameters of the bronchopulmonary tract compliance, airway resistance, calculating the inhalation time constant, and on this basis, the correspondence between the support pressure and the inspiration volume is determined, so that the pressure in respiratory tract was minimally possible. The claimed algorithm seeks to withstand the pattern of breathing, the least tiring and traumatic for the patient's body - while ensuring the required ventilation. The algorithm works continuously and adapts the breathing pattern to changes in the parameters of the patient's bronchopulmonary system.

At the output of the formula, the respiratory rate, a single volume of inspiration is obtained as the quotient of dividing the minute volume by frequency. And the required pressure is selected empirically so that, subject to a full inhalation-exhalation, give the desired single volume.

Not all variants of the ratio of tidal volume to respiratory rate determined by the Otis formula are safe for the patient. At a very low frequency, a large tidal volume is required to achieve the target MV, which can cause volatility to the patient's lungs. At the same time, at a high respiratory rate, the tidal volume approaches the volume of dead space, which will lead to ventilation of only the dead space and the absence of alveolar ventilation. Such states do not occur with small deviations in the parameters of respiratory mechanics (compliance, resistance), which are transported to the Otis formula through an expiratory constant. However, with more significant deviations of these parameters from the norm, the risk of volumotrauma or hypoventilation increases sharply.

Thus, to ensure the safety of patient ventilation, the application of restrictions on the upper and lower limits of frequency, tidal volume and pressure is required. Some of these boundaries are dynamic and depend on the respiratory mechanics of the patient.

The established limiting limitation of the specific coefficient of MOD does not allow the operation of equipment in which the specified method is applied in modes that could cause irreversible consequences for the patient. The application of the limit value of the MOD correction is based on permissible physiological parameters.

If the patient shows signs of spontaneous breathing, the method should be implemented in such a way as to complement the patient's independent respiratory function, directly responding to the onset of inspiration and expiration. If the body performs a respiratory function in an insufficient volume for its full functioning, the functional parameters of supplying the patient with the respiratory mixture are adjusted in such a way as to complement the patient's own efforts to implement the function of external respiration.

The calculation of the permissible boundaries of the parameters of the respiratory function is carried out to prevent the application of injuries of the respiratory tract of various nature. If the respiratory rate rises, the MOD increases, i.e. pressure support of spontaneous breaths - until the frequency stabilizes. If the respiratory rate reaches the safety limit, a warning about the need for intervention is transmitted through the controller and the information output device.

At the beginning of a hardware inspiration, the time of the respiratory cycle is not fixed. Only the maximum allowable inspiratory time is prescribed, according to the criterion of the minimum respiration rate. The exhalation will last as long as there is a decreasing flow of exhaled gas. The exhalation phase is the most vulnerable in the respiratory cycle, since inhalation is performed by the entire power of the apparatus, and exhalation is only the elastic properties of the patient's respiratory muscles. The method gives priority to ensuring complete exhalation, for this it will consistently shorten the inhalation, raise the pressure of the inspiration, remove the final, least valuable phase. With spontaneous breathing, the patient himself determines the optimal respiratory rate and expiration time, the method and apparatus in which this method is used only creates the specified support pressure for inspiration and switches from inspiration to exhalation.

Ensuring full breath is a subordinate parameter in relation to ensuring full exhalation. At the beginning of a hardware inspiration, the time of the actual inspiration is not recorded. Inhalation will continue until the inspiratory flow drops to a level determined by the algorithm (usually zero — this is a full inspiration) or until the maximum inspiratory time expires or one of the safety limits is reached. A full breath is not as demanding as a full breath, because its violation does not directly harm the patient, but a full breath reduces the support pressure to the minimum possible for a given volume of breath and maximizes the improvement of gas exchange in the lungs.

Implemented in the proposed method, the adjustment of the coefficient MOD depending on the state of the respiratory system of the patient can significantly reduce the risk of volumotrauma, hypo- and hyperventilation.

In the transition from hardware breathing to supporting the spontaneous efforts of the patient, the proposed method allows to stimulate the patient to breathe by holding a hardware breath. The amount of delay is set by the doctor depending on the patient's condition.

With a patient’s steady breathing, if there is a delay with another spontaneous breath, the device does not provide the patient with a hardware breath, but holds a pause, stimulating the patient to resume spontaneous breathing. Depending on the physical condition of the patient and his (un) readiness for excommunication, its duration is from 0 to 4 periods of breathing. Thus, stimulation of one's own breathing does not lead to hypoxia, hypercapnia, or excessive patient fatigue.

The group of inventions, namely the functional diagram of the components of the artificial lung ventilation apparatus in which the claimed method is used, is illustrated in FIG. 1 is a structural diagram of a ventilator.

The decoding of the components indicated by the numbers in FIG. 1 is given below:

1 - gas mixer

2 - Inspiratory flow sensor

3 - flow generator

4 - inspiratory pressure sensor;

5 - expiratory pressure sensor;

6 - Valve exhalation;

7 - expiratory flow sensor;

8 - Controller (ventilation);

9 - display controller;

10 - Display with touch screen;

11 - Inspiration line;

12 - The line of exhalation.

The following is an example implementation of a method of artificial ventilation of the lungs and a device that implements these methods.

The first step is to calculate the ideal body weight (IBW). IBW in kg for adult patients is defined as follows, for men and women with growth from 130 to 250 cm:

for men: IBW = 0.908 * height (cm) -88.022

for women: IBW = 0.905 * height (cm) -92.006

IBW for children (up to 130 cm) is determined by centile tables.

In children with a height of 130 to 150 cm, ideal weight is calculated as in adult patients.

Next, the calculation of the minute volume of breathing (MOD).

For adult patients, the determination of the target MOD is carried out according to the following formula:

MV = IBW * Kmv *% MV;

Where:

MV is the minute volume of breathing;

% MV - coefficient of minute volume of breathing, the default is 100%, the adjustment range is from 25% to 220%;

IBW - ideal body weight (in kg);

Kmv - specific coefficient of minute volume of breathing.

For adults, Kmv is 0.1 L / kg IBW.

Kmv for children with IBW up to 5 kg is 0.3 l / kg IBW.

Kmv for children with IBW from 5 to 30 kg is determined by the formula:

Kmv = 0.34- (0.008 * IBW);

Kmv for children with IBW above 30 kg corresponds to the Kmv of an adult patient.

At the next stage, the ratio of the respiratory rate and the depth of breaths is calculated according to the Otis formula:

Figure 00000006

Where:

Figure 00000007

Figure 00000008

RB is the respiratory rate;

MV is the minute volume of breathing;

V d is the volume of dead space;

For hardware breathing:

Tidal volume is determined by dividing the target minute volume by the target frequency:

Figure 00000009

Where;

V t - inspiratory volume;

MV is the minute volume of breathing;

RB is the respiratory rate;

The required pressure is selected empirically - so that, subject to a full inhalation-exhalation, give the desired single volume.

For spontaneous breathing:

The required pressure to support spontaneous breaths is selected so as to reach the required minute volume.

Next, the boundaries of safe ventilation are determined and controlled.

Upper tidal volume safety margin:

Figure 00000010

but not more:

Vt max≤22 * IBW, ml .;

Where:

Plimit = Pmax-10 cm H2O;

Pmax - upper limit of safe pressure set by the operator;

Cst - static compliance;

22 * IBW - ten calculated dead spaces (V d ), estimated dead space - 2.2 ml / kg IBW.

PEEP - positive pressure at the end of exhalation;

At the same time (second condition): Vt max cannot be less than Vt min.

The lower limit of tidal volume safety is two calculated dead spaces:

Vt min = 2 * Vd

or

Vt min = 4.4 ml / kg * IBW.

Upper limit of respiratory rate safety:

RB max = 60 / (3 * RCexp) = 20 / RCexp;

but not more than 60 / min and not less than RB min;

Where:

RCexp is an expiratory constant.

Lower respiratory rate safety margin:

RB min - depends on the ideal weight of the patient, is determined in accordance with the data given in table 1.

Figure 00000011

Minimum expiration time:

Te min - at least 2 * RC;

Where:

RC - expiratory constant

Minimum inspiration time:

Ti min - not less than 1 RC, but not less than 0.5 sec in adults and children, weighing more than 10 kg, in children less than 10 kg IBW not less than 0.35 sec.

Modification of the MOD can be made.

The starting minute volume of breathing (% MV = 100) is a fairly average value calculated for a healthy person in a passive state who has an average metabolic rate. The calculated value of MV does not guarantee the development of hypo- or hyperventilation, although extreme and gross deviations are largely excluded. Upon adaptation, the% MV prescribed by the doctor becomes the lower limit of MV retention, the upper limit depends on the patient’s spontaneous breathing rate, but is limited by an absolute value of 220.

The range of automatic adaptation% MV is defined as follows: lower limit: the value% MV set by the operator; upper absolute limit: 220%; adjustment step - 2%; maximum adjustment speed - 2% for each breath; working conditions for increasing% MV: the presence of at least 5 consecutive spontaneous breaths.

MV adaptation is carried out when spontaneous RB leaves the boundaries of the calculated dynamic range defined by the values RBs max and RBs min.

If RB spont> RBs max, then% MV rises.

If RB spont <RBs min, then% MV is reduced (provided that% MV has risen before).

If RBc min <RB spont <RBc max, then% MV does not change.

Range Boundaries:

RBs min is the target RB defined by the Otis equation taking into account the% MV premium;

RBs max is defined as RBc min + 5;

% MV - current value, including changed after the correction.

At a frequency of spontaneous breaths above RBs max - 1% is added to the current MV value, at a frequency below the current value RBs min - 1% is taken. If a spontaneous inhalation does not occur within the time determined by the frequency according to the Otis equation calculated without the addition of% MV (according to the operator set the% MV value), a hardware inhalation is performed. That is, during adaptation, the equation is solved simultaneously twice, for the case with the MV premium and without it (for the set value% MV). In the first case, RBs min is obtained to reduce% MV, in the second - for the case of apnea, that is, to enable hardware breaths. When setting% MV above 220 - adaptation is disabled.

The operator can set the range of normal CO 2 content in the patient's output stream (according to the capnograph), as well as the upper and lower limits of% MV, in which the% MV correction is allowed. If the CO 2 content has exceeded the upper limit of the specified range, then hypoventilation is likely, and% MV rises until the upper limit is reached or the CO 2 readings enter the range. If the CO 2 content is below the set lower limit of the range, then hyperventilation is likely, and% MV decreases until the lower limit is reached or the CO 2 readings enter the range.

The adjustment speed is applied the same as that of tachypnea adaptation.

An artificial lung ventilation device in which the disclosed method is used operates as follows.

The process of ventilation is divided into a continuous sequence of respiratory cycles. The respiratory cycle consists of the inspiratory phase and the expiratory phase. Inhalation is created by the apparatus by creating excess pressure in the lungs, exhalation occurs due to the elasticity of the chest. When creating excessive pressure on inspiration, a portion of fresh oxygen-enriched gas enters the lungs. When you exhale, excess gas is removed from the lungs and carries off carbon dioxide released by the body. The device is connected to the patient’s lungs with the inspiratory line 11 and the exhalation line 12.

The process of inspiration and expiration in the device is controlled by the ventilation controller 8. The user interface supports the display controller through the display and touch screen.

The inspiration process is as follows, FIG. 1. The exhalation valve 6 closes, and the fresh gas stream created by the flow generator 3 flows through the inspiration line 11 into the patient's lungs. The size of the flow and its shape in time is controlled by the ventilation controller 8, by creating control actions on the flow generator 3. The gas mixer 1, by command from the ventilation controller, creates the desired oxygen concentration in the fresh gas.

The pressure in the inspiratory and expiratory pipelines is measured using pressure sensors located respectively in the inspiratory 4 and expiratory pipelines 5. The signals from the flow sensors 2 and 7, pressure 4 and 5 are fed to the ventilation controller 8, where they are digitized. Next, the conversion results are sent to the control program, which, according to a special algorithm, generates control actions on the flow generator 3 and the exhalation valve 6.

Also, signals from flow sensors 2, 7 and pressure 4, 5 are used to calculate the parameters of the patient's bronchopulmonary system - compliance (compliance) and aerodynamic resistance, which are the basis for determining the respiratory rate and inspiration duration.

Inhalation is interrupted at a time depending on the type of ventilation: if it is ventilation with volume control, then the flow is interrupted after issuing a predetermined volume, if it is ventilation with pressure control, the flow is interrupted when the desired pressure is reached.

The inspiratory volume is determined using the flow sensor 2 located in the inspiratory line. At its core, flow sensors 2 and 7 of the flow measure the mass of the flowing gas. The mass flow is recalculated into the volume flow using calculation formulas, which also include temperature and absolute pressure.

There are two types of respiratory cycles: hardware - initiated by the ventilator; spontaneous - initiated by the patient. The device supports spontaneous breaths, providing the set pressure of support on inhalation.

After the end of the inhalation, the exhalation valve is opened, and under the action of the elasticity force of the chest, gas flows from the lungs to the atmosphere through the exhalation line 12 and the exhalation valve 6. The device has the ability to change the degree of closure of the exhalation valve, which allows you to control the flow and pressure on the exhale.

The exhalation valve has an electromagnet that creates the required pressure on the membrane, and the membrane can completely or partially block the exhalation line. The exhalation valve also has a flow sensor 7, which measures the flow rate and the volume of gas passing through the exhalation valve. The value of the gas flow on the exhale is used to control the tightness of the circuit, and also allows the difference method to calculate the flow that enters the patient's lungs:

F lungs = F inhale -F exhale

The inspiratory flow is divided into two parts - one of them enters the patient's lungs (F lungs ), the second goes into the exhalation valve (F exhalation ). The expiratory flow F is reserve in case of sudden effort of inspiration from the patient.

The amount of flux F lung is used to calculate the effects in the control program according to the rules of the selected ventilation mode. The differences between the ventilation modes are only in the ways of controlling the flow on the inhale, the flow on the exhale and the time point for switching from inhalation to exhalation, while the operation of the main components of the apparatus described above in the different ventilation modes is unchanged.

The device can be manufactured using materials and means of production traditionally used in the manufacture of such devices.

Claims (64)

1. A method of performing artificial ventilation of the lungs, including determining the target minute breathing volume based on the ideal body weight and specific coefficient of the minute breathing volume, calculating the ratio of the respiratory rate and tidal volume corresponding to the minimum respiratory work, calculating the safe boundaries of the respiratory rate, tidal volume, inspiratory time and expiratory time, and the retention of the target minute volume of respiration when changing the respiration rate in the calculated safe boundaries, characterized in that the starting specific coefficient of the minute volume of breathing is established, and the minute volume of breathing is automatically adjusted within a predetermined range when the spontaneous breathing rate goes beyond the limits of the calculated dynamic range, but not less than the minute volume of breathing established taking into account the starting coefficient of the minute volume of breathing.
2. A method of performing artificial ventilation of the lungs according to claim 1, characterized in that the minute volume of respiration is automatically adjusted in the range,%: from the established starting specific coefficient of the minute volume to 220.
3. The method of implementing artificial lung ventilation according to claim 2, characterized in that the upper limit of the adjustment of the minute volume of breathing is limited by the absolute value,%: 220.
4. The method of implementing artificial ventilation of the lungs according to claim 2, characterized in that the lower limit of the minute volume of respiration is established on the basis of calculating the ideal body weight and selecting a specific coefficient for the minute volume of respiration.
5. The method of implementing artificial lung ventilation according to claim 4, characterized in that the lower limit of the minute volume of breathing is established by the formula:
MV = IBW * Kmv *% MV; Where:
MV is the lower limit of the minute volume of respiration;
% MV - coefficient of minute volume of breathing, the default is 100%, the adjustment range is from 25% to 220%;
IBW - ideal body weight (in kg);
Kmv - specific coefficient of minute volume of respiration;
for adults, Kmv is 0.1 l / kg IBW;
Kmv for children with IBW up to 5 kg is 0.3 l / kg IBW;
Kmv for children with IBW from 5 to 30 kg is determined by the formula:
Kmv = 0.34 - (0.008 * IBW);
Kmv for children with IBW above 30 kg corresponds to the Kmv of an adult patient.
6. The method of implementing artificial lung ventilation according to claim 1, characterized in that the upper limit of the tidal volume is determined by the formula:
Figure 00000012
Where:
V Tmax - the upper limit of the tidal volume;
P max - the upper limit of the safe pressure set by the operator;
PEEP - positive pressure at the end of exhalation;
C st - static compliance;
K v - maximum volume ratio (default - 22)
IBW - ideal body weight;
V Tmin is the lower boundary of the tidal volume.
7. A method of implementing artificial lung ventilation according to claim 1, characterized in that the lower boundary of the tidal volume is determined by the formula:
[V Tmin = 2⋅V d = 4.4⋅IBW, where:
V Tmin is the lower boundary of the tidal volume;
V d is the estimated volume of dead space;
IBW - ideal body weight.
8. The method of implementing artificial ventilation of the lungs according to claim 1, characterized in that the upper limit of the safety of respiratory rate is determined by the formula:
Figure 00000013
Where:
RB max is the upper limit of the safe respiratory rate;
RC exp - expiratory constant;
RB min is the lower limit of the safe respiratory rate.
9. The method of implementing artificial lung ventilation according to claim 1, characterized in that the lower limit of the safe frequency of respiratory depression is determined by the dependence:
RB min = f (IBW);
Where:
RB min is the lower limit of the safe respiratory rate;
IBW - ideal body weight.
10. The method of implementing artificial lung ventilation according to claim 1, characterized in that the minimum expiration time is determined by full expiration (zero flow from the patient’s lungs) or stabilization of the flow, but not more than Max max ,
Where:
Te max = 11 sec.
11. The method of implementing mechanical ventilation according to claim 1, characterized in that the minimum inspiratory time is determined by the formula:
Figure 00000014
Where:
Ti min - minimum inspiration time;
Ti P is the pressure build -up time;
Ti f - time to reduce the flow to a level determined by the program (usually zero - for a full breath);
Ti max = 3 ... 5 sec depending on the expiratory constant.
12. The method of implementing artificial lung ventilation according to claim 1, characterized in that the minute volume of breathing is further adjusted depending on the content of CO 2 in the output stream
13. The method of implementing artificial lung ventilation according to claim 11, characterized in that the adjustment of the minute volume of breathing is additionally carried out in accordance with the following algorithm: setting the upper and lower values of the range of CO 2 content in the output stream, measuring the actual CO 2 content in the output stream, comparison of the actual content of CO 2 in the output stream with the upper value of the specified range of the content of CO 2 , comparison of the real content of CO 2 in the output stream with the lower value of the specified range of the content of CO 2 2 , adjusting the minute volume of respiration when the actual CO 2 content goes beyond the boundaries of a certain range of CO 2 contents, repeating the cycle until the actual CO 2 content in the exhaled stream enters the given range of CO 2 values in the exhaled stream.
14. The method of implementing artificial lung ventilation according to claim 11, characterized in that the CO 2 content in the exhalation fraction is determined by means of a capnograph;
15. The method of implementing artificial lung ventilation according to claim 11, characterized in that the rate of adjustment of the minute volume of respiration is 2% for each breath.
16. An artificial lung ventilation apparatus comprising a gas mixer, a flow sensor, a flow generator, inhalation and exhalation lines, pressure sensors located in the inhalation and exhalation lines, an exhalation valve and a flow sensor located at the outlet of the exhalation valve, a ventilation controller electrically connected to a gas mixer, flow sensors, a flow generator, an exhalation valve and pressure sensors, and an information input and output device connected to a ventilation controller, characterized in that the ventilation controller is configured with the possibility of obtaining data from flow and pressure sensors, calculating the parameters of the inspiratory volume, suppleness and aerodynamic resistance, calculating the ratio of the respiratory rate and tidal volume corresponding to the minimum respiratory work, calculating the safe boundaries of the respiratory rate, tidal volume, inspiratory time and expiratory time, holding the target minute breathing volume when changing the respiratory rate within the calculated safe limits, adjusting the minute volume of breathing within a predetermined range and at an output frequency of spontaneous breathing beyond the dynamic range calculated by the control action on the flow generator and an exhalation valve.
17. The artificial lung ventilation apparatus according to claim 15, characterized in that the ventilation controller is configured to receive data from flow sensors and according to the formula:
F lungs = F inspiratory -F exhalation ;
Where:
F lungs - the flow of gas entering the patient’s lungs;
F inspiration - gas flow at the inlet (on the tee, taking into account the contour);
F exhalation is the gas flow at the outlet (on the tee, taking into account the circuit),
moreover, the ventilation controller is configured to use the Finale value to calculate the control action on the flow generator and the exhalation valve.
.
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