DE102008060799B3 - Controller for ventilators to control a variable pressure assist ventilation - Google Patents

Abstract

The invention relates to a controller (1) for ventilators (8) for regulating variable pressure assist ventilation based on the variability of a respiratory system (2), wherein the respiratory system (2) is in the form of a subject (Pi) with intrinsic variability the breath volume (VT) and a respiratory rate is provided, containing properties of the respiratory system (2) and the ventilation work. The solution is that the controller (1) is able to calculate the variability in terms of fluctuations (DeltaVT) of the breath volume (VT) relative to a mean (VTM) and associated mean (VTM) to given breath lift volume values in a given one Breath lift volume target range (VTO-VTU) while a pressure assist value (PASB) is applied to the predetermined breath volume target area (VTO-VTU) according to the mechanical properties of the respiratory system (2) and the variability of the breathing pattern (111, 113, 114, 115, 116), wherein the controller (1) consists of the following components: - an evaluation unit (4) for collecting the properties of the breathing pattern (111, 113, 114, 115, 116), - a comparison unit (5) for testing compliance with predetermined limits (VTO, VTU) within a breath volume target range (VTO-VTU) with respect to a mean (VTM) or a mean standard deviation (RF) of the breath volume ens (VT), - a ...

Description

The The invention relates to a controller for ventilators for regulation a variable pressure assist ventilation.

One Breathing patterns of patients whose breathing is supported by a ventilator draws through a regularity or a low change - variability - of breath volumes and respiratory rate off. This is due to several factors, being as variability the Fluctuation of breath volume and respiratory rate by one Mean value is defined. On the one hand, the supported spontaneous breathing performed under analgesic sedation, which leads to a reduction in respiratory variability. Second, the underlying underlying disease of the patient to a reduction in the variability of the breathing pattern to lead. Third, most conventional forms of ventilation are based on a rigid support Respiration without regard to the patient's own intrinsic variability.

An adaptation of respiratory or adaptive assisted spontaneous breathing - ASB - based on respiratory parameters has already been described several times in pamphlets. The adaptive assisted spontaneous breathing ASB as a ventilation form is described in the document Laubscher et al .: An adaptive ventilation controller, IEEE Trans. Biomed. Eng., 41: 51-59, 1994, and aims to adapt ventilator ventilation to respiratory conditions in ventilated patients. The respiratory rate and respiratory stroke volume parameters are adjusted by a ventilator controller to provide an operator-specified volume of air per minute (minute volume), and the combination of parameters may minimize ventilator work. The controller consists of an internal or external to the ventilator computing unit, which detects the respiratory rate and the average Atemhubvolumen over a monitoring time. A respiratory effort minimization algorithm sets the respiratory rate and calculates the adaptively adjusted assist _pressure value P _ASB , which enables the resulting breath lift volume. If the patient's respiratory rate is too low, breaths are generated in a controlled manner by the ventilator, ie ventilation cycles are initiated to reach the adjusted respiratory rate. A problem of the method is that the spontaneous variability of the breathing pattern is not replicated and the ventilator can not adapt to the variability - the fluctuations of the breath volume around an intended mean value V _TM . Another problem is the disruption of synchrony between the ventilator and the patient when the ventilator generates a ventilation cycle independent of the inspiratory effort of the patient.

A proportionally supported Ventilation (English: Proportional Assist Ventilation - PAV) as a respiratory form is in the publication: Proportional assist ventilation, a new approach to ventilatory support, Theory, Am. Rev. Respir. Dis., 145, pp. 114-120, 1992, described in which the support pressure proportional to respiratory gas flow and breath volume varies. The goal is here in that the respiratory effort increased by resistance and elasticity of the ventilator compensated and adapted the ventilation to the needs of the patient becomes.

In 1a is the course V _T (t) of a Atemhubvolumens 11 over the time t - over a fixed monitoring time t _ÜZ of about twenty minutes - under PAV conditions according to the prior art. The mean value V _TM (t) is initially in the breath volume target area V _TO -V _TU , but increases as the monitoring time t over the upper limit V _TO of Arbeitsshubvolumen target area V _TO -V _TU , without the ventilator this Development, where V _{TU is} the lower limit of the mean breath volume. The variability of the values of the breath volume V _T results solely from the variability of the inspiratory effort and in this case is lower than the variability, which can lead to an adaptation of the gas exchange and the lung mechanical properties.

The Main problem of proportionally assisted ventilation - PAV - exists in that the control of the pressure support of the accuracy of the Measurement of resistance and elasticity of the patient's breathing dependent is. Accordingly, if the parameters are miscalculated, an over- or Undercompensation of ventilation work can be generated and thus too low or high breath volumes without the ventilator against controls such a development. Another problem with this form of ventilation then, if the patient's effort is less variable, what often To observe a breathing pattern with compared to spontaneous breathing reduced variability - d. H. slight fluctuations in breath volume - results.

A protocol for the automatic weaning of patients from the ventilator - SCPS - is in the document: A knowledge-based system for assisted ventilation of patients in intensive care units, Int. J. Clin. Monit. Comput., 9, pp. 239-250, 1992, in which the mean assist pressure value P _ASB of adaptive spontaneous breathing is adjusted based on the measured average breath volume. The goal here is to change be compensated for the mechanical properties of the ventilator, wherein the target area of the average breath volume depends on the basic clinical picture of the patient.

In 1b is the course V _T (t) of the breath volume 111 over time t, using the auto-weaning protocol after removal of the ventilator for five states X ₁ , X ₂ , X ₃ , X ₄ , X ₅ according to the prior art. The mean value V _{TM1 of} the breath volume 111 during the first monitoring time t _ÜZ1 of two minutes in phase X ₁ is initially above the upper limit V _TO of Atemhubvolumen target range V _TO -V _TU . After reduction of the mean assist _pressure value P _ASB by the protocol controller, an average value V _{TM2 of} the _{breath lift} volume _becomes 111 achieved, which is during the second monitoring time t _ÜZ2 in phase X ₂ in _{Atemhubvolumen} target range V _TO -V _TU . In the third monitoring time t _ÜZ3 in phase X ₃ , the mean value V _{TM3 of} the breath volume remains 111 within the breath volume target range V _TO -V _TU , so that no intervention by the protocol controller is necessary. In the fourth monitoring time t _ÜZ4 of phase X ₄ , the _{breath lift} volume values and thus the mean value V _TM4 calculated in this time _increase , so that the protocol controller again has to adjust the mean assist _pressure value P _ASB . In the fifth and last mapped monitoring time t _ÜZ5 in the phase X ₅ , the _{breath lift} volume target range V _TO -V _TU for the mean value V _TM5 of _{Atemhubvolumens} 111 reached. The variability of the values of the breath volume is hardly influenced by the variability of the inspiratory effort due to the almost constant fluctuations, since a fixed preset assist pressure value P _ASB is generated, ie without extrinsic variability. Although the protocol controller is capable of calculating the mean V _TM (t) of breath volume 111 to adjust, the variability of the breathing pattern is unaffected by the protocol controller. Thus, an adaptation of the gas exchange and the lung mechanical properties by the protocol controller can not be achieved.

One special problem of the protocol controller is that the support pressure after controlled by the mean breath volume and the variability of the breathing pattern is not considered. Therefore, with constant respiratory effort of the patient a breathing pattern with reduced variability result. As result of the protocol controller is unable to adapt gas exchange and lung mechanics.

As part of a variable pressure support ventilation (NPSV), which in the publication DE 10 2006 052 572 B3 Respiration is supported with randomly generated pressure values by adaptively adjusted assist pressure - PASB - thus producing the variability of the breathing pattern independent of the intrinsic variability of the patient.

In 1c is the course V _T (t) of the breath volume 112 over the time t with variable pressure support - NPSV - shown in the prior art. Although the variability of the breath lift volume is high enough to allow the adjustment of gas exchange and lung mechanical properties, the mean V _TM (t) of the breath lift volume is initially above the breath lift volume target range V _TO -V _TU and develops instably over time t, because there is no feedback system. The relatively high and low mean values V _TM (t) can lead to impaired lung function, and secondly, the summation of the variability of the patient's inspiratory effort and the variability of the assist pressure value P _ASB generated by the ventilator can result in a the adaptation of the gas exchange and the lung mechanical properties lead to high variability of the breath volume.

One problem, however, is that while the patient is being weaned from the ventilator, the intrinsic variability of the breathing pattern may increase due to the reduction in analgesic sedation or the improvement in health status. At this stage there may be a summation of generated extrinsic variability and intrinsic variability of the respiratory pattern. Thus, there is a chance that the unphysiologically increased total, ie intrinsic variability plus extrinsic variability, may affect respiratory function and / or respiratory comfort. Another problem is that the ventilator's increased variability of the breathing pattern can lead to a change in the lung mechanical properties of the connected patient. At a fixed average of the adaptive assist pressure P _ASB , this may result in an increase or decrease in the breath lift volume target range V _TO -V _TU , which does not correspond to patient demand. The breath lift volume target range V _TO -V _TU represents a range of the breath volume V _T between the upper limit V _TO and the lower limit V _TU .

Neurally adjusted ventilation assist (NAVA) is described in Sinderby et al: Neural control of mechanical ventilation in respiratory failure, Nat. Med., 5, pp. 1433-1436, 1999, in which the electromyographic activity of the Zwerch Fells detected by placed in the esophagus electrodes and the pressure support of the ventilator is controlled in proportion to the electromyographic activity. A potential problem with NAVA is the need to attach a special esophageal probe, which can lead to esophageal mucosal injury. Another problem is that the variability of the breathing pattern under the NAVA is dependent on the intrinsic variability of the respiratory center of the patient, therefore the variability in certain conditions or deep sedation of the patients may be reduced and result in a relatively less variable breathing pattern.

The Main problem of the aforementioned methods and devices for assisted Spontaneous breathing is that orientation to the surrogate parameters the respiratory function occurs without taking into account the variability of the ventilator. The problem is, in particular, that with constant breathing effort of the Patients or with the same mechanical properties of the ventilator a breathing pattern with unphysiologically low variability results.

Of the Invention is based on the object, a controller for ventilators for control a variable pressure assist ventilation indicate that is designed so that the respiratory Function, the breathing comfort can be increased can. It should be based on the intrinsic variability of Atemhubvolumens and the Respiratory rate of the patient generated by the ventilator extrinsic variability be modulated. It should also be possible that the total variability within a predefined range. simultaneously the mean airway support pressure should be adjusted to an adequate one to ensure a medium breath volume and to ensure adequate ventilation of the patient.

• – einer Auswertungseinheit zur Erhebung der Eigenschaften des Atemmusters,
• – einer Vergleichseinheit zur Testung der Einhaltung von vorgegebenen Grenzen V_TO, V_TU innerhalb eines Atemhubvolumen-Zielbereiches V_TO–V_TU in Bezug auf den Mittelwert V_TM und einer mittleren Standardabweichung RF des Atemhubvolumens V_T,
• – einer Entscheidungseinheit mit vorgegebenen Entscheidungsalgorithmen, welche zu einer Anpassung des Mittelwertes V_TM oder der mittleren Standardabweichung RF des Unterstützungsdruckwertes P_ASB führen, und
• – einer Sendeeinheit mit vorgegebenen komplexen Verteilungen von Unterstützungsdruckwerten P_ASB, welche einzeln oder als paketartige Serie zum Beatmungsgerät gesendet werden, wobei die Komplexität irreguläre Schwankungen des Drucks um einen Mittelwert darstellt.

The object is solved by the features of claims 1 and 5. The controller for ventilators for controlling a variable pressure assist ventilation, which is based on the variability of a respiratory system, wherein the respiratory system in the form of a subject P _{i is provided} with the intrinsic variability of the breath volume V _T and a respiratory rate, containing properties of the respiratory system and the ventilation work,
is according to the characterizing part of patent claim 1
able to guide the variability in terms of fluctuations ΔV _{T of} the breath volume V _T relative to a mean value V _TM and the associated mean value V _TM to predetermined breath volume values in a predetermined breath volume target range V _TO -V _TU , while a pressure assist value P _ASB In order to achieve the predetermined breath volume target area V _TO -V _TU according to the mechanical properties of the respiratory system and the variability of the respiratory pattern, the controller consists of the following components:

• An evaluation unit for ascertaining the properties of the breathing pattern,
• A comparison unit for testing compliance with predetermined limits V _TO , V _TU within a breath volume target range V _TO -V _TU with respect to the mean value V _TM and a mean standard deviation RF of the breath volume V _T ,
• - A decision unit with predetermined decision algorithms, which lead to an adjustment of the mean value V _TM or the mean standard deviation RF of the support pressure value P _ASB , and
• A transmission unit with predetermined complex distributions of assist pressure values P _ASB , which are sent individually or as a packet-like series to the ventilator, the complexity representing irregular fluctuations of the pressure around an average value.

The associated ventilator can essentially consist of a ventilation device and an consist of the ventilation device connected to the respiratory connection, the controller in the ventilator being assigned externally or internally can be.

The controller can be involved in a controlled system, the information requested on properties of the breathing pattern and the change of the settings of the NPSV mode in the form of support pressure-P _ASB sequences with predefined distributions, such. B. a normal distribution with a fixed average and a fixed mean standard deviation, are made on the basis of the decision algorithm in the decision unit of the controller on the ventilator.

The subject can be connected to the ventilator via the respiratory connection and have an intrinsic variability CVi, whereby the variability of the parameter and the subject variability of the respiratory pattern in the controller are determined by decision rules, the external variability CVP _{ASB of} the support pressure P _{ASB is} calculated. The values of the variabilities V are indicated in the controller by coefficients C and processed.

In the method for controlling a variable pressure assist ventilation by means of As mentioned in the characterizing part of patent claim 5, the controller assigned to a respirator is adapted to adapt the extrinsic variability of the assisting pressure P _ASB to the intrinsic variability of the subject connected to the respirator, the variability of the breathing pattern being provided for assisted spontaneous breathing control.

In this case, the ventilator with the controller for a plurality of following predetermined monitoring _times t _ÜZ1 , t _ÜZ2 , t _ÜZ3 , t _ÜZ4 , t _ÜZ5 on the basis of occurring and registered by the controller states X ₁ , X ₂ , X ₃ , X ₄ , X ₅ Operated controlled system.

In an occurring condition X ₁ , the mean value V _{TM1 of} the breath volume V _T during the first monitoring time t _ÜZ1 in the predetermined minute range is initially above the upper limit V _{TO Atemhubvolumen} target range V _TO -V _TU , characterized in that the mean value V _TM1 outside the upper limit V _TO of Atemhubvolumens V _T is carried out by the controller, a reduction in the assist pressure _value P _ASB .

In an occurring state X ₂ after lowering of the assist _pressure value P _ASB by the controller, an average value V _TM2 of _{Atemhubvolumens} V _{T is} reached, which is during the second monitoring time t _ÜZ2 in the predetermined minute range within the _{Atemhubvolumen} target range V _TO -V _TU .

In an occurring state X ₃ in a subsequent third monitoring time t _ÜZ3 , the mean value V _{TM3 of} the breath volume V _T remains within the Atemhubvolumen target area V _TO -V _TU , but by a controller initiated increase of the external variability CVP _{ASB of} the support pressure P _ASB increase the absolute values of the maxima and the minima of the breath volume V _T , wherein the peaks of the maxima of the Atemhubvolumens V _T exceed the upper limit V _TO .

In an occurring state X ₄ during a fourth monitoring time t _ÜZ4 , the increased breath-stroke volume amplitude _values are almost maintained when the _{assist pressure} P _{ASB is lowered} , but the average value V _TM4 is raised above the upper limit V _TO .

In a occurring state X ₅ in a fifth monitoring time t _{ÜZ5 the Atemhubvolumen} target range V _TO -V _TU for the average value V _TM5 of _{Atemhubvolumens is} not exceeded at the approximately same Atemhubvolumen amplitude values, wherein the variability of the Atemhubvolumens V _T therefore by the variability the inspiratory effort is influenced, since a variable assist pressure value P _{ASB is} generated and now the controller is able to adjust the mean value V _TM (t) of the breath volume V _T and to influence the variability of the breathing pattern by the controller Adjustment of the gas exchange and the lung mechanical properties in the ventilator by the controller is achieved.

From the completed adjustments, the stable fifth state X ₅ in the rectangle between the Atemhubvolumen target range V _TO -V _TU and the two percentage fixed limits CV _U V _T (lower limit) and CV _O V _T (upper limit) of the coefficient of variation of the Atemhubvolumens V _T reached.

• – Schritt 4.0: Die Auswertung der Eigenschaften des jeweiligen Atemmusters im Sinne ihrer statistischen Beschreibung mit dem Mittelwert V_TM und der mittleren Standardabweichung RF, der exspiratorischen Zeit Te, der inspiratorischen Zeit Ti, der Atemzyklusdauer Ttot, dem Atemwegsspitzendruck Ppeak und dem mittleren Atemwegsdruck über die Überwachungszeit t_ÜZ in der Auswertungseinheit erfolgt, wobei diese Informationen vom Beatmungsgerät abgefragt bzw. anhand des Atemfluss- und Atemwegsignals berechnet werden, wobei der IST-Zustand festgestellt wird und wobei iCV für die gemessene IST-Variabilität eines Parameters steht,
• – Schritt 5.1: Der Vergleich der gemessenen Mittelwerte V_TM1, V_TM2, V_TM3, V_TM4, V_TM5 des Atemhubvolumens mit der vom Bediener angegebenen Untergrenze V_TU erfolgt in der Vergleichseinheit, wobei bei Erfüllung dieser Bedingung der Kontroller zum Schritt 6.0 übergeht, der in der Entscheidungseinheit stattfindet,
• – Schritt 6.0: Der adaptive Unterstützungsdruck P_ASB wird um eine Unterstützungsdruckdifferenz ΔP_ASB erhöht und der Kontroller geht zum Schritt 7.0, der in der Sendeeinheit stattfindet, wobei das dort erhaltene Signal an das Beatmungsgerät übermittelt wird, wobei, falls das Signal des Schrittes 5.1 negativ ist, zum Schritt 5.2 in der Vergleichseinheit übergegangen wird,
• – Schritt 5.2: Der Vergleich des jeweils gemessenen Mittelwertes V_TM des Atemhubvolumens mit der vom Bediener angegebenen Obergrenze V_TO findet in der Vergleichseinheit statt, wobei bei Erfüllung dieser Bedingung der Kontroller zum Schritt 6.1 übergeht, der in der Entscheidungseinheit stattfindet,
• – Schritt 6.1: Der Unterstützungsdruck P_ASB wird um eine Unterstützungsdruckdifferenz ΔP_ASB reduziert und der Kontroller geht über zum Schritt 7.0, der in der Sendeeinheit stattfindet,
• – Schritt 5.3: Es erfolgt ein Vergleich des gemessenen Variationskoeffizienten CVV_T des Atemhubvolumens V_T mit der vom Bediener angegebenen Untergrenze CV_UV_T des Variationskoeffizienten des Atemhubvolumens, wobei bei Erfüllung dieser Bedingung der Kontroller zum Schritt 6.21 übergeht,
• – Schritt 6.21: Der Kontroller berechnet koeffizientenbezogen die zusätzlich zu erzeugende, externe Variabilität CVeP_ASB bezüglich des Unterstützungsdrucks P_ASB anhand von Entscheidungsregeln, wobei die zusätzlich zu erzeugende, externe Variabilität CVe eine Funktion von CVV_T, CVRF, CVTi/Ttot, CVTi, CVTe, V_TM, mittlere RF mit CVe= f(CVV_T, CVRF, CVTi/Ttot, CVTi, CVTe, mittlerer V_TM, mittlere RF) ist, wobei eine einfache Funktion der extrinsischen Variabilität CVe = sCVV_T – iCVV_T als Differenz der SOLL-Variabilität sCVV_T und der IST-Variabilität iCVV_T verwendbar ist und der Kontroller zum Schritt 6.22 übergeht,
• – Schritt 6.22: Die neue, zu erzeugende, externe Variabilität CVP_ASB mit CVP_ASBneu wird als die letzte CVP_ASB gegenüber CVP_ASBalt plus CVe mit Gleichung CVP_ASBneu = CVP_ASBalt + CVe berechnet und die neue Sequenz von Unterstützungsdruck-P_ASB-Werten an die Beatmungseinrichtung geschickt, welches diese unter Überwachung des Kontrollers durchführt und der Kontroller zum Schritt 7.0 übergeht,
• – Schritt 5.4: Der Vergleich der gemessenen Variabilität des Atemhubvolumens V_T mit der vom Bediener angegebenen Obergrenze CV_OV_T des Variationskoeffizienten des Atemhubvolumens V_T erfolgt in der Vergleichseinheit, wobei bei Erfüllung dieser Bedingung der Kontroller zum Schritt 6.31 übergeht,
• – Schritt 6.31: Der Kontroller berechnet koeffizientenbezogen die abzuziehende Variabilität in P_ASB (CVe) anhand von Entscheidungsregeln, wobei CVe = f(CVV_T, CVRF, CVTi/Ttot, CVTi, CVTe, V_TM, mittlere RF), wobei als die einfache Funktion CVe = |sCVV_T – iCVV_T| verwendbar ist und der Kontroller geht über zum Schritt 6.32, der in der Entscheidungseinheit 6 durchgeführt wird,
• – Schritt 6.32: Die neue zu erzeugende, externe Variabilität CVP_ASB mit CV P_ASBneu wird als die letzte CVP_ASB gegenüber CVP_ASBalt minus CVe berechnet nach Gleichung CVP_ASBneu = CVP_ASBalt – CVe, wobei Minima für CVe und CVP_ASB festgelegt werden, und wobei die neue Sequenz von Unterstützungsdruck-P_ASB-Werten an das Beatmungsgerät geschickt wird, welches diese unter Überwachung des Kontrollers durchführt und der Kontroller geht über zum Schritt 7.0,
• – Schritt 7.0: Der Kontroller sendet die neu berechneten Mittelwerte V_TM5 des Atemhubvolumens und mittleren Standardabweichungen des Unterstützungsdrucks P_ASB zum Beatmungsgerät.

The method is carried out by means of installed program engineering means in the controller in relation to the state phases X ₁ , X ₂ , X ₃ , X ₄ , X ₅ in the functional units of the controller in several steps:

• - Step 4.0: The evaluation of the characteristics of each respiratory pattern in terms of their statistical description with the mean value V _TM and the mean standard deviation RF, the expiratory time Te, the inspiratory time Ti, the respiratory cycle duration Ttot, the peak airway pressure Ppeak and the mean airway pressure over the monitoring time t _TS takes place in the evaluation unit, this information is requested from the respirator or on the basis of respiratory flow and calculated Atemwegsignals, wherein the actual state is detected and wherein iCV stands for the measured actual variability of a parameter,
• Step 5.1: The comparison of the measured mean values V _TM1 , V _TM2 , V _TM3 , V _TM4 , V _{TM5 of} the breath volume with the operator-specified lower limit V _TU is performed in the comparison unit, upon fulfillment of this condition, the controller goes to step 6.0, which takes place in the decision-making unit,
• Step 6.0: The adaptive assist pressure P _ASB is increased by an assist pressure difference ΔP _ASB and the controller proceeds to step 7.0 which takes place in the transmitter unit, where the signal received therefrom is transmitted to the ventilator, if the signal of step 5.1 is negative is transferred to step 5.2 in the comparison unit,
• Step 5.2: The comparison of the respectively measured mean value V _{TM of} the breath lift volume with the operator-specified upper limit V _TO takes place in the comparison unit, whereby, when this condition is fulfilled, the controller moves to step 6.1, which takes place in the decision unit,
• Step 6.1: The assist pressure P _ASB is reduced by a assist pressure difference ΔP _ASB and the controller proceeds to the step 7.0, which takes place in the transmitting unit,
• Step 5.3: The measured coefficient of variation CVV _{T of} the breath volume V _{T is} compared with the operator-specified lower limit CV _U V _{T of} the coefficient of variation of the breath volume. If this condition is fulfilled, the controller transfers to step 6.21.
• Step 6.21: The controller calculates coefficient-related the external variability CVeP _ASB to be generated with respect to the assist pressure P _ASB using decision rules, the additional external variability CVe being a function of CVV _T , CVRF, CVTi / Ttot, CVTi, CVTe , V _TM , mean RF with CVe = f (CVV _T , CVRF, CVTi / Ttot, CVTi, CVTe, mean V _TM , mean RF), with a simple function of extrinsic variability CVe = sCVV _T - iCVV _T as the difference of Target variability sCVV _T and the actual variability iCVV _{T is} usable and the controller goes to step 6.22,
• Step 6.22: The new external variability CVP _ASB to be generated with CVP _ASBnew is calculated as the last CVP _ASB against CVP _ASBold plus CVe with equation CVP _ASBnew = CVP _ASBalt + CVe and the new sequence of support pressure P _ASB values sent the ventilator, which performs this under supervision of the controller and the controller goes to step 7.0,
• Step 5.4: The comparison of the measured variability of the breath volume V _T with the operator-specified upper limit CV _O V _{T of} the coefficient of variation of the breath volume V _T is performed in the comparison unit, upon fulfillment of this condition, the controller goes to step 6.31,
• Step 6.31: The controller calculates the coefficient to be deducted variability in P _ASB (CVe) using decision rules, where CVe = f (CVV _T , CVRF, CVTi / Ttot, CVTi, CVTe, V _TM , medium RF), where as the simple Function CVe = | sCVV _T - iCVV _T | is usable and the controller goes over to step 6.32, which is in the decision unit 6 is carried out,
• Step 6.32: The new external variability CVP _ASB to be generated with CV P _ASBnew is calculated as the last CVP _ASB against CVP _ASBalt minus CVe according to equation CVP _ASBnew = CVP _ASBalt - CVe, where minima are set for CVe and CVP _ASB , and the new sequence of assist pressure P _ASB values being sent to the ventilator, which is performed under supervision of the controller, and the controller proceeds to step 7.0,
• Step 7.0: The controller sends the recalculated averages V _{TM5 of} the breath volume and mean standard deviations of the assist _pressure P _ASB to the ventilator.

The Advantages of the invention are that the technical implementation one on the variability of the breathing pattern based controller is more practicable than the previously used method, since neither additional sensors nor the plant of Measuring probes on the patient are necessary. Moreover, it is with the invention possible, the weaning phase of the patient after removal of the ventilator because of the variability of the breathing pattern with the success of ventilator cessation is associated.

further developments and further embodiments of the invention are specified in further subclaims.

The Invention is by means of an embodiment with reference to several Drawings described in more detail.

It shows:

1 several breath lift volume (V _T ) time (t) curves, where

1a a breath-lift volume (V _T ) time (t) curve with variable values, but without adjustment of the mean level or its variability during a proportionally assisted ventilation - PAV - according to the prior art,

1b a breath lift volume (V _T ) time (t) curve with adjustment of the mean airway pressure level to achieve a breath lift volume target area of the mean breath lift volume but without affecting the variability of the airway pressure level during the protocol for automatic weaning of patients after removal of the ventilator - SCPS - according to the prior art, and

1c Breath lift volume (V _T ) time (t) curves with variable pressure assistance - NPSV - but without adjusting the variability and mean airway pressure level of the prior art,
demonstrate,

2 a schematic structure of a ventilator with a controller with associated functional units,

3 a general schematic representation of a controller according to the invention for ventilators for controlling a variable pressure assist ventilation, based on the variability of a breathing pattern, within a controlled system,

4 Functional representations of he according to the invention 2 and 3 , in which

4a Breath lift volume (V _T ) time (t) curves for control by the controller of the invention with adjustment of the mean and externally generated variability of the airway pressure level to achieve a breath lift volume target range of a coefficient of variation or a mean value of the breath lift volume;

4b a mean value (V _TM ) variation coefficient (CV) representation of the action for variability-controlled adjustment of the assist pressure after 4a and

4c a circuit design of the controller after 2 in conjunction with the representation of the functional steps - flow diagram - for the regulation of the variable pressure support ventilation in the ventilator
demonstrate.

In 2 is a general schematic representation of the controller according to the invention 1 for ventilators to control variable pressure assist ventilation, based on the variability of a respiratory system 2 based, while the respiratory system 2 in the form of a subject P _i with the intrinsic variability of the breath volume V _T and a respiratory rate, and in the controller 1 Properties of the respiratory system 2 and the ventilation work are included.

• – einer Auswertungseinheit 4 zur Erhebung der Eigenschaften des Atemmusters 111, 113, 114, 115, 116,
• – einer Vergleichseinheit 5 zur Testung der Einhaltung von vorgegebenen Grenzen V_TO, V_TU innerhalb eines Atemhubvolumen-Zielbereiches V_TO–V_TU in Bezug auf einen Mittelwert V_TM und einer mittleren Standardabweichung RF des Atemhubvolumens V_T,
• – einer Entscheidungseinheit 6 mit vorgegebenen Entscheidungsalgorithmen, welche zu einer Anpassung des Mittelwertes V_TM oder der mittleren Standardabweichung RF des Unterstützungsdruckwertes P_ASB führen, und
• – einer Sendeeinheit 7 mit vorgegebenen komplexen Verteilungen von Unterstützungsdruckwerten P_ASB, welche einzeln oder als paketartige Serie zum Beatmungsgerät 8 gesendet werden, wobei die Komplexität irreguläre Schwankungen des Drucks um einen Mittelwert darstellt.

According to the invention, the controller 1 being able to guide the variability in the form of variations ΔV _{T of} the breath volume V _T relative to the mean value V _TM and the associated mean value V _TM to predetermined breath lift volume values in a predetermined target breath volume target range V _TO -V _TU , while a pressure assist value P _ASB is applied to the predetermined Atemhubvolumen target area V _TO -V _TU according to the mechanical properties of the respiratory system 2 and the variability of the breathing pattern 111 . 113 . 114 . 115 . 116 to reach, with the controller 1 consists of the following components:

• - An evaluation unit 4 to survey the properties of the breathing pattern 111 . 113 . 114 . 115 . 116 .
• - a comparison unit 5 for testing compliance with predetermined limits V _TO , V _TU within a breath volume target range V _TO -V _TU with respect to a mean value V _TM and a mean standard deviation RF of the breath volume V _T ,
• - a decision-making unit 6 with predetermined decision algorithms which lead to an adaptation of the mean value V _TM or the mean standard deviation RF of the support pressure value P _ASB , and
• - a transmission unit 7 with predetermined complex distributions of support pressure values P _ASB , which individually or as a packet-like series to the respirator 8th the complexity being irregular fluctuations in pressure around an average.

The ventilator 8th in 2 can be from a ventilator 9 and one to the ventilator 9 connected ventilation port 10 exist, with the controller 1 in the ventilator 8th can be assigned externally or internally. To the ventilation device 9 In addition to a pressure / flow generator and a pressure / flow sensor, it may include an internal computer with internal memory. The in 2 shown controllers 1 can be external to the ventilator 9 Being connected, according to 3 the controller 1 in the following controlled system 3 included:
The controller 1 can be internal or external to the ventilator 8th to be appropriate. From the ventilator 8th which operates in the NPSV mode - the variable pressure assist ventilation - with the assist pressure P _ASB become the information on characteristics of the breath pattern 111 . 113 . 114 . 115 . 116 and changing the settings of the NPSV mode in the form of support pressure P _ASB sequences with predefined distributions, such as A normal distribution with a fixed average and a fixed mean standard deviation, are determined by the decision algorithm in the decision unit 6 from the controller 1 on the ventilator 8th performed. The subject 2 (Patient) is above the ventilation port 10 to the ventilator 8th connected and has an intrinsic variability CVi. From the nominal variability sCV the parameters of the respiratory pattern and the subject 2 (Patient) measured actual variability iCV of the breathing pattern is in the controller 1 calculated by decision rules the external variability CVP _{ASB of} the support pressure P _ASB .

The operation of the controller according to the invention 1 to control the variable pressure assist ventilation is in accordance with the 4 with the 4a . 4b and 4c explained in more detail.

In 4a is the course V _T (t) of the breath volume 111 . 113 . 114 . 115 . 116 are shown over the time t of two minutes each for five states X ₁ , X ₂ , X ₃ , X ₄ , X ₅ . The mean value V _{TM1 of} the breath volume 111 is during the first monitoring time t _ÜZ1 of two minutes in phase X ₁ initially above the upper limit V _TO of Atemhubvolumen target range V _TO -V _TU . Characterized in that the mean value V _TM1 outside the upper limit V _TO of Atemhubvolumens 111 is done by the controller 1 a decrease in the assist pressure _value P _ASB . After lowering of the assist pressure _value P _ASB in phase X ₂ by the controller 1 becomes an average value V _{TM2 of} the breath volume 113 which is within the _{Atemhubvolumen} target range V _TO -V _TU during the second monitoring time t _ÜZ2 of two minutes. In the third monitoring time t _ÜZ3 in phase X ₃ , the mean value V _{TM3 of} the breath _capacity remains 114 although within the Atemhubvolumen target area V _TO -V _TU , but by one of the controller 1 initiated increase of the external variability CVP _{ASB of} the support pressure P _ASB increase the absolute values of the maxima and the minima of the breath volume 114 , where the peaks of the maxima of Atemhubvolumens 114 exceed the upper limit V _TO . During the fourth monitor time t _ÜZ4 in the phase X ₄ , the increased _{breath lift} volume amplitude values are almost maintained as the _{assist pressure} P _{ASB is lowered} , but the average value V _TM4 is raised above the upper limit V _TO . In the fifth and last monitored monitoring time t _ÜZ5 in phase X ₅ , the breath- _lift volume target range V _TO -V _TU for the mean value V _TM5 of _{Atemhubvolumens} 116 not exceeded in the approximately same Atemhubvolumen amplitude values. The variability of the breath volume V _T is therefore influenced by the variability of the inspiratory effort, since a variable assist pressure _value P _{ASB is} generated. Now the controller 1 is able to adjust the mean value V _TM (t) of the breath volume V _T becomes the variability of the breathing pattern 111 . 113 . 114 . 115 . 116 through the controller 1 affected. Thus, an adaptation of the gas exchange and the lung mechanical properties in the ventilator 8th through the controller 1 be achieved.

4b In a V _TM (t) representation, the states X ₁ , X ₂ , X ₃ , X ₄ , X ₅ and the adjustment of the assist pressure P _ASB and the coefficient of variation CVP _{ASB are} shown. From the completed adjustments, the stable fifth state X ₅ in the rectangle between the Atemhubvolumen target range V _TO -V _TU and the two limits CV _U V _T (lower limit) and CV _O V _T (upper limit) of the coefficient of variation of the Atemhubvolumens V _T reached.

The controller according to the invention 1 for variable pressure assist ventilation - NPSV - operates according to its installed program resources 4c with reference to the state phases X ₁ , X ₂ , X ₃ , X ₄ , X ₅ completed in sequence, with the following steps, wherein the reference numerals of the steps correspond to the functional units 4 . 5 . 6 . 7 the controller 1 assigned.

Step 4.0: The evaluation of the properties of the respiratory pattern 111 . 113 . 114 . 115 . 116 in the sense of their statistical description, eg. B. the mean value V _TM and the mean standard deviation RF, the expiratory time (Te), the inspiratory time (Ti), the respiratory cycle duration (Ttot), the peak airway pressure (Ppeak) and the mean airway pressure over the monitoring time t _ÜZ , for example two minutes, takes place in the evaluation unit 4 , This information is provided by the ventilator 8th queried or calculated on the basis of the respiratory flow and airway signal. The actual state is determined, where iCV stands for the measured actual variability of a parameter.

The controller 1 then go to step 5.1.

Step 5.1: The comparison of the measured mean value V _TM1 , V _TM2 , V _TM3 , V _TM4 , V _{TM5 of} the breath volume with the operator-specified lower limit V _TU , which may be 420 ml for an adult of 1.70 m height, for example in the comparison unit 5 , If this condition is met, the controller goes 1 about to step 6.0, in the decision-making unit 6 takes place.

Step 6.0: The adaptive assist pressure P _ASB is increased by a assist pressure difference ΔP _ASB , which may be, for example, two cmH ₂ O, and the controller 1 go to step 7.0, which is in the sender unit 7 takes place, with the signal received there to the ventilator 8th is transmitted.

If the signal of step 5.1 is negative, then the step 5.2 in the comparison unit 5 passed:

Step 5.2: The comparison of the measured mean value V _T , the breath lift volume with the operator-specified upper limit V _TO , which may for example be 560 ml for an adult with a height of 1.70 m, is found in the comparison unit 5 instead of. If this condition is met, the controller goes 1 about to step 6.1, in the decision-making unit 6 takes place.

Step 6.1: The assist pressure P _ASB is reduced by a assist pressure difference ΔP _ASB , which is, for example, two cmH ₂ O, and the controller 1 goes to step 7.0, which is in the sender unit 7 takes place.

Step 5.3: The comparison of the measured coefficient of variation CVV _T of Atemhubvolumens V _T with the operator specified lower limit CV _U V _{TM of} the coefficient of variation of the breath capacity, which may be, for example, 20% for an adult. If this condition is met, the controller goes 1 to step 6.21.

Step 6.21: The controller 1 charged koef In terms of efficiency, the external variability CVeP _ASB to be generated with respect to the assist pressure P _{ASB is} determined by decision rules, with the additional external variability CVe to be a function of CVV _T , CVRF, CVTi / Ttot, CVTi, CVTe, V _TM , mean RF CVe = f (CVV _T , CVRF, CVTi / Ttot, CVTi, CVTe, mean V _TM , mean RF). For example, the simple function of the extrinsic variability CVe = sCVV _T - iCVV _{T can be used} as the difference between the nominal variability sCVV _T and the actual variability iCVV _T. The controller 1 go to step 6.22.

Step 6.22: The new external variability CVP _ASB to be generated with CVP _ASB new is calculated as the last CVP _ASB against CVP _ASBalt plus CVe calculated using equation CVP _ASBnew = CVP _ASBalt + CVe and the new sequence of support pressure P _ASB values the ventilation device 9 sent this under supervision of the controller 1 performs. The controller 1 go to step 7.0.

Step 5.4: The comparison of the measured variability of the breath volume V _T with the operator-specified upper limit CV _O V _{TM of} the coefficient of variation of the breath volume V _T , which may for example be 30% for an adult, is performed in the comparison unit 5 , If this condition is met, the controller goes 1 via to step 6.31.

Step 6.31: The controller 1 calculates coefficient-deductible variability in P _ASB (CVe) using decision rules, where CVe = f (CVV _T , CVRF, CVTi / Ttot, CVTi, CVTe, V _TM , mean RF). For example, the simple function CVe = | sCVV _T - iCVV _T | be used. The controller 1 goes to step 6.32, which is in the decision-making unit 6 is carried out.

Step 6.32: The new external variability CVP _ASB to be generated with CVP _ASBnew is calculated as the last CVP _ASB against CVP _ASBalt minus CVe according to equation CVP _ASBnew = CVP _ASBalt - CVe, where minima are set for CVe and CVP _ASB , for example 0% or 5% and the new sequence of support pressure-P _ASB values to the ventilator 8th sent this under supervision of the controller 1 performs. The controller 1 go to step 7.0.

Step 7.0: The controller 1 sends the recalculated mean values V _{TM5 of} the breath volume and mean standard deviations of the assist _pressure P _ASB to the ventilator 8th ,

In summary, in the controller 1 an adaptation of the extrinsic variability of the support pressure P _ASB to the intrinsic variability of the patient with stored program resources, wherein the variability of the breathing pattern is provided for the regulation of the assisted spontaneous breathing.

1

controller

2

respiratory system

3

controlled system

4

evaluation

5

comparing unit

6

decision unit

7

transmission unit

8th

ventilator

9

ventilator

10

respiration connection

11

breathing pattern

111

breathing pattern

112

breathing pattern

113

breathing pattern

114

breathing pattern

115

breathing pattern

116

breathing pattern

V _T

Tidal volume

V _TM

Average of breath volume

V _TU

lower limit the mean breath volume

V _TO

Upper limit the mean breath volume

V _TO -V _TU

Tidal volume target range

X ₁

first Status

X ₂

second Status

X ₃

third Status

X ₄

fourth Status

X ₅

fifth condition

t

Time

t _ÜZ

monitoring time

P _ASB

support print

CV

the coefficient of variation

CV i

intrinsic variability

CVe

extrinsic variability

SCV

DESIRED variability

iCV

IS variability

CVP _ASB

external variability of support pressure

RF

middle standard deviation

Te

expiratory Time

Ti

inspiratory Time

Tdead

Respiratory cycle duration

ppeak

Airway peak pressure

ΔP _ASB

Support pressure difference

CV _U V _T

lower limit the coefficient of variation of Atemhubvolumens

CV _O V _T

Upper limit the coefficient of variation of Atemhubvolumens

Claims (13)

Controller ( 1 ) for ventilators ( 8th ) to the Re a variable pressure assist ventilation based on the variability of a respiratory system ( 2 ), whereby the respiratory system ( 2 ) in the form of a subject (P _i ) with the intrinsic variability of the breath volume (V _T ) and a respiratory rate containing properties of the respiratory system ( 2 ) and the ventilation work, characterized in that the controller ( 1 ) is capable of determining the variability in terms of fluctuations (ΔV _T ) of the breath volume (V _T ) relative to a mean (V _TM ) and associated mean (V _TM ) to predetermined breath lift volume values in a predetermined breath lift volume target range (V _TO -V _TU ), while a pressure assist value (P _ASB ) is applied to the predetermined breath-stroke volume target area (V _TO -V _TU ) according to the mechanical properties of the respiratory system (FIG. 2 ) and the variability of the breathing pattern ( 111 . 113 . 114 . 115 . 116 ), whereby the controller ( 1 ) consists of the following components: - an evaluation unit ( 4 ) for collecting the properties of the breathing pattern ( 111 . 113 . 114 . 115 . 116 ), - a comparison unit ( 5 ) for testing compliance with predetermined limits (V _TO , V _TU ) within a breath volume target range V _TO - (V _TU ) with respect to a mean value (V _TM ) or a mean standard deviation (RF) of the breath volume (V _T ); - a decision-making unit ( 6 ) with predetermined decision algorithms which lead to an adaptation of the mean value (V _TM ) or the mean standard deviation (RF) of the assist pressure value (P _ASB ), and - a transmission unit ( 7 ) with predetermined complex distributions of assist pressure values (P _ASB ), which can be used individually or as a packet-like series to the ventilator ( 8th ), the complexity being irregular fluctuations in pressure around an average. Controller according to claim 1, characterized in that the associated ventilator ( 8th ) from a ventilation device ( 9 ) and one to the ventilation device ( 9 ) connected ventilation port ( 10 ), whereby the controller ( 1 ) in the ventilator ( 8th ) is assigned externally or internally. Controller according to claim 1, characterized in that the controller ( 1 ) in a controlled system ( 3 ), the information on characteristics of the breathing pattern ( 111 . 113 . 114 . 115 . 116 ) and changing the settings of the variable pressure assist ventilation mode - the NPSV mode - in the form of assist pressure P _ASB sequences with predefined distributions, such as. A normal distribution with a fixed average and a defined mean standard deviation, based on the decision algorithm in the decision unit ( 6 ) from the controller ( 1 ) on the ventilator ( 8th ). Controller according to claim 1, characterized in that the subject ( 2 ) via the ventilation port ( 10 ) to the ventilator ( 8th ) and an intrinsic variability (CVi), whereby the parameters of the respiratory pattern and of the subject (sCV) 2 ) actual variability (iCV) of the respiratory pattern in the controller ( 1 ) is calculated on the basis of decision rules, the external variability (CVP _ASB ) of the support pressure (P _ASB ). Method for regulating variable pressure assist ventilation by means of a ventilator ( 8th ) assigned controller ( 1 ) according to claim 1, characterized in that an adaptation of the extrinsic variability of the support pressure (P _ASB ) to the intrinsic variability of the ventilator ( 8th ) connected subject ( 2 ), whereby the variability of the breathing pattern ( 111 . 113 . 114 . 115 . 116 ) is provided for the regulation of assisted spontaneous breathing. A method according to claim 5, characterized in that in several following predetermined monitoring _times (t _ÜZ1 , t _ÜZ2 , t _ÜZ3 , t _ÜZ4 , t _ÜZ5 ) based on occurring and by the controller ( 1 ) registered conditions (X ₁ , X ₂ , X ₃ , X ₄ , X ₅ ) the ventilator ( 8th ) with the controller ( 1 ) after a controlled system ( 3 ) is operated. A method according to claim 6, characterized in that in an occurring state (X ₁ ) of the mean value (V _TM1 ) of Atemhubvolumens ( 111 ) is in the predetermined minute range during the first monitoring time (t _ÜZ1 ) initially above the upper limit (V _TO ) of Atemhubvolumen target area (V _TO -V _TU ), wherein in that the mean value (V _TM1 ) outside the upper limit (V _TO ) of the breath volume ( 111 ) by the controller ( 1 ) a reduction in the assist _{pressure value} (P _ASB ) takes place. A method according to claim 6, characterized in that in an occurring state (X ₂ ) after lowering of the assist pressure value (P _ASB ) by the controller ( 1 ) an average value (V _TM2 ) of the breath volume ( 113 ) is reached, which during the second monitoring time (t _ÜZ2 ) within the predetermined minute range within the Atemhubvolumen target range (V _TO -V _TU ). A method according to claim 6, characterized in that in an occurring state (X ₃ ) in a third monitoring time (t _ÜZ3 ), the average value (V _TM3 ) of the breath volume ( 114 ) remains within the breath-lift volume target range (V _TO -V _TU ), but by one from the controller ( 1 ) increase the external variability (CVP _ASB ) of the support pressure (P _ASB ) increase the absolute values of the maxima and minima of the breath volume ( 114 ), wherein the peaks of the maxima of the breath volume ( 114 ) exceed the upper limit (V _TO ). A method according to claim 6, characterized in that in an occurring state (X ₄ ) during a fourth monitoring time (t _ÜZ4 ) the increased _{Atemhubvolumen} amplitude values are almost maintained when lowering the support _pressure (P _ASB ), but the average (V _TM4 ) over the upper limit (V _TO ) is raised. A method according to claim 6, characterized in that in an occurring state (X ₅ ) in a fifth monitoring time t _ÜZ5 the _{Atemhubvolumen} target area (V _TO -V _TU ) for the mean value (V _TM5 ) of Atemhubvolumens ( 116 The variability of the breath volume (V _T ) is therefore influenced by the variability of the inspiratory effort, since a variable assist pressure _value (P _ASB ) is generated and now the controller ( 1 ) is capable of adjusting the mean value (V _TM (t)) of the breath volume (V _T ) and the variability of the breathing pattern ( 111 . 113 . 114 . 115 . 116 ) by the controller ( 1 ), whereby an adaptation of the gas exchange and the lung mechanical properties in the ventilator ( 8th ) by the controller ( 1 ) is achieved. A method according to claim 11, characterized in that from the completed adjustments of the stable fifth state (X ₅ ) in the rectangle between the Atemhubvolumen target area (V _TO -V _TU ) and the two percentage limits (CV _U V _T , CV _O V _T ) of the coefficient of variation of the Atemhubvolumens (V _T ) is achieved. Method according to claims 5 to 12, characterized in that it is realized by means of installed program engineering means in the controller ( 1 ) relative to the state phases (X ₁ , X ₂ , X ₃ , X ₄ , X ₅ ) completed in the functional units ( 4 . 5 . 6 . 7 ) of the controller ( 1 ) in several steps: - Step 4.0: the evaluation of the properties of the respective breathing pattern ( 111 . 113 . 114 . 115 . 116 ) in terms of their statistical description with mean (V _TM ) and mean standard deviation (RF), expiratory time (Te), inspiratory time (Ti), respiratory cycle duration (Ttot), peak airway pressure (Ppeak), and mean airway pressure over the monitoring time (t _ÜZ ) takes place in the evaluation unit ( 4 ), the information from the ventilator ( 8th ) and are calculated on the basis of the respiratory flow and airway signal, whereby the actual state is determined and where (iCV) represents the measured actual variability of a parameter, step 5.1: the comparison of the measured average values (V _TM1 , V _TM2 , V _TM3 , V _TM4 , V _TM5 ) of the breath volume with the lower limit (V _TU ) specified by the operator takes place in the comparison unit ( 5 ), whereby upon fulfillment of this condition the controller ( 1 ) moves to step 6.0, which in the decision-making unit ( 6 ) takes place, - Step 6.0: The adaptive assist pressure (P _ASB ) is increased by an assist pressure difference (ΔP _ASB ) and the controller ( 1 ) goes to step 7.0, which in the transmitting unit ( 7 ) takes place, wherein the signal received there to the ventilator ( 8th ), wherein, if the signal of step 5.1 is negative, to step 5.2 in the comparison unit ( 5 ), - Step 5.2: The comparison of the respectively measured mean value (V _TM ) of the breath lift volume with the upper limit (V _TO ) specified by the operator takes place in the comparison unit ( 5 ), whereby upon fulfillment of this condition, the controller ( 1 ) goes to step 6.1, which in the decision-making unit ( 6 ) takes place, - Step 6.1: The assist pressure (P _ASB ) is reduced by a support pressure difference (ΔP _ASB ) and the controller ( 1 ) goes to step 7.0, which in the transmitting unit ( 7 ) takes place, - Step 5.3: A comparison is made of the measured coefficient of variation (CVV _T ) of the breath volume (V _T ) with the operator-specified lower limit (CV _U V _T ) of the coefficient of variation of the breath volume, in which case the controller ( 1 ) goes to step 6.21, - step 6.21: the controller ( 1 ) calculates the additional external variability (CVeP _ASB ) to be generated with respect to the assist pressure (P _ASB ) by decision rules, wherein the additional external variability (CVe) to be generated is a function of (CVV _T , CVRF, CVTi / Ttot, CVTi , CVTe, V _TM , mean RF) with CVe = f (CVV _T , CVRF, CVTi / Ttot, CVTi, CVTe, mean V _TM , mean RF), with a simple function of extrinsic variability CVe = sCVV _T - iCVV _T is used as the difference of the nominal variability (sCVV _T ) and the actual variability (iCVV _T ) and the controller ( 1 ), step 6.22: The coefficient-related new external variability (CVP _ASB ) to be generated with (CVP _ASBnew ) is considered last (CVP _ASB ) _vs CVP _ASBalt plus CVe with equation CVP _ASBnew = CVP _ASBalt + CVe calculates the new sequence of assist pressure P _ASB values to the ventilator ( 9 ), which this under supervision of the controller ( 1 ) and the controller ( 1 ) goes to step 7.0, Step 5.4: The comparison of the measured variability of the breath volume (V _T ) with the operator-specified upper limit (CV _O V _T ) of the coefficient of variation of the breath volume (V _T ) is carried out in the comparison unit ( 5 ), whereby upon fulfillment of this condition the controller ( 1 ) goes to step 6.31, - step 6.31: the controller ( 1 ) calculates coefficient-deductible variability in P _ASB (CVe) according to decision rules, where CVe = f (CVV _T , CVRF, CVTi / Ttot, CVTi, CVTe, V _TM , mean RF), where as the simple function CVe = | sCVV _T - iCVV _T | is usable and the controller ( 1 ) goes to step 6.32, which is in the decision-making unit 6 The coefficient-related new external variability to be generated (CVP _ASB ) with CV P _ASBnew is calculated as the last one (CVP _ASB ) versus CVP _ASBalt minus CVe according to the equation CVP _ASBnew = CVP _ASBalt -CVe, where Minima for (CVe) and (CVP _ASB ), and where the new sequence of assist pressure P _ASB values to the ventilator ( 8th ), which this under supervision of the controller ( 1 ) and the controller ( 1 ) goes to step 7.0, - Step 7.0: The controller ( 1 ) sends the newly calculated mean values (V _TM5 ) of the breath volume and mean standard deviation of the support _pressure (P _ASB ) to the ventilator ( 8th ).