Apparatus and method for ventilating a patient

Abstract

The invention relates to a plurality of ventilation devices, a ventilation device with a visualizing device and a method for operating a ventilation device. The aim is to minimize the energy input into at least one respiratory tract of a patient due to ventilation.

Description

[0001] This application is a divisional application of patent application number 201880021033.0 filed in the Chinese Patent Office on January 25, 2018 and entitled “Apparatus and method for ventilating a patient”. TECHNICAL FIELD

[0002] The subject matter of the present invention relates to a ventilation device / lung ventilation device, a ventilation device with a visualizing device and a method for ventilating / ventilating a patient. The ventilation device comprises at least a fluid supply unit and in addition a fluid discharge unit, which are adapted to supply fluid, in particular at least predominantly respiratory gas, into at least one respiratory tract of a patient, i.e. into the lung parts or lungs, and to discharge fluid from the respiratory tract, respectively. BACKGROUND

[0003] When ventilating / ventilating a patient, usually a mask or a tube is used. A gas or gas mixture, in particular oxygen and air, is supplied via the mask or tube at low pressure to the respiratory tract, which is sealed off from the outside. Alternatively, however, this gas or gas mixture can also be injected in a pulsed manner at high pressure and high flow rate via a thin tube lumen (catheter, cannula or tube) into the respiratory tract, which is open to the outside (so-called jet ventilation). This method is currently used in particular in the context of diagnosis and therapy in the upper respiratory tract region (endotracheal jet ventilation or trans-tracheal jet ventilation). The method can also be applied in emergency situations outside the hospital environment or in in-patients in the hospital.

[0004] In trans-tracheal jet ventilation, the patient can be supplied with oxygen or fluid by means of a catheter introduced directly through the skin into the trachea or a cannula placed accordingly. These methods (trans-tracheal / endotracheal) are an integral part of the effective algorithms currently used to manage difficult respiratory tracts, in particular in situations in which the patient cannot be ventilated or cannulated by conventional means (so-called “ventilation impossible, cannulation impossible” situations).

[0005] Furthermore, from WO 2008 / 113752 A1 and WO 2015 / 004229 A1, a gas flow reversal device is known with which ventilation (inspiration and expiration) can also be carried out exclusively via the tube lumen.

[0006] Artificial or mechanical ventilation is carried out in a controlled manner or in the form of an aid to spontaneous breathing. In the first case, the ventilation device (ventilator) has complete control over the breathing pattern, while in the second case the at least partially autonomous patient has considerable influence on the breathing pattern. However, a common feature of all forms of ventilation is that the ventilation device has almost complete influence on the inhalation phase. From the perspective of the ventilator, expiration can be carried out passively, i.e. driven by the energy stored in the lungs and the elastic tissue elements of the thorax.

[0007] Various ventilation methods are known. Frequently performed is volume-controlled ventilation, in which all ventilation parameters are predetermined. The target parameter and the control parameter are the tidal volume (breathing volume) V T The resulting airway pressure depends on the set volume and the condition of the patient's lung system. The regulating parameters are thus the volume flow, the ventilation frequency, the peak inspiratory pressure (PIP) and the end-expiratory pressure (EEP). The end-expiratory pressure includes the end-expiratory positive pressure (PEEP), the end-expiratory zero pressure (ZEEP) and the end-expiratory negative pressure (NEEP). The following discussion always refers to PEEP. The peak inspiratory pressure (PIP) represents the highest positive pressure artificially produced in the airway during ventilation. It can also be set as an alarm limit in order to prevent, preferably always, the exceeding of this pressure value. The end-expiratory positive pressure (PEEP) represents the positive pressure artificially produced in the airway during ventilation and which exists after the completion of expiration.

[0008] In pressure-controlled ventilation, an initially high volume flow is continuously reduced when, for example, a pressure rise is detected in the airway or outside the airway and within the ventilation device. The target parameter and the control variable are thus the pressure. It is thus not possible to regulate the volume flow here; however, the volume flow is detected and an alarm limit can be defined.

[0009] In contrast to the spontaneous breathing of a patient, in artificial ventilation, fluid is supplied in a manner that counteracts the elasticity of the airway. Due to the elevated pressure in the thoracic cavity, PEEP and PIP reduce the flow of venous blood back to the heart, as a result of which the cardiac output can drop. Conversely, hyperemia occurs in the superior and inferior vena cava, and the pressure in the upstream organs correspondingly rises. Depending on the level of PEEP and PIP, this can lead to damage and impaired function of the brain, liver, kidneys and other organs. SUMMARY

[0010] On the basis of this, it is an object of the present application to propose an improved ventilation device and an improved ventilation method. In particular, the ventilation is intended to be performed in a manner that is as individualized as possible; that is, the characteristics of the patient to be ventilated are to be taken into account as fully as possible. Furthermore, the ventilation is to be as gentle as possible, and in any case, damage to the airway and other organs must be prevented. In particular, a ventilation device is proposed that allows such a ventilation to be performed.

[0011] This object is achieved by a ventilation device having the features of claim 1, 9, 17, 18, 21, 22 and by a method having the features of claim 11, 19, 23. The subject of the dependent claims is advantageous variants and embodiments of the ventilation device and method. It is noted that features individually specified in the dependent claims can be combined with each other in a technically meaningful manner and define further embodiments of the invention. Furthermore, features specified in the description with more precision and explanation than in the claims present further preferred embodiments of the invention.

[0012] A (first) ventilation device for ventilating a patient is proposed, which comprises at least a fluid supply unit and a fluid exhaust unit, which are adapted to supply fluid into at least one respiratory tract of the patient (i.e. into a lung component or into the lungs) and to exhaust fluid from the respiratory tract, respectively; and further comprises a control device. The control device is configured for setting the profile / outline / course of the pressure P [cm H2O or millibar] in the respiratory tract and the profile / outline / course of the volume V [milliliter] of fluid supplied to and exhausted from the respiratory tract in dependence on V = f ZP (P) and V = f AP (P) or in dependence on P = f ZV (V) and P = f AV (V) during a ventilation process, which occurs within a pressure interval; wherein the ventilation process can be set by the control device in such a way that:

[0013] a) over at least 60%, in particular over at least 80% of the pressure interval,

[0014] - the absolute value of the measure of the change of the first volume, which is present during the supply of fluid at the pressure P0, i.e. df AP / d(P)(P0) and

[0015] - the absolute value of the measure of the change of the second volume, which is present during the exhaust of fluid at the same pressure P0, i.e. df ZP / d(P)(P0)

[0016] the ratio

[0017] has a value of at least 0.5 and at most 2.0

[0018] or

[0019] b) over at least 60%, in particular over at least 80% of the volume interval,

[0020] - the absolute value of the measure of the change of the first pressure present at the volume V0 during the supply of fluid, i.e. df AV / d(V)(V0) and

[0021] - the absolute value of the measure of the change of the second pressure present at the same volume V0 during the discharge of fluid, i.e. df ZV / d(V)(V0)

[0022] the ratio of

[0023] has a value of at least 0.5 and at most 2.0.

[0024] In particular, the volume [in millilitres] is determined via the control device. Thereby, the supply rate or discharge rate of fluid is measured or monitored (i.e. the volume flow rate in millilitres per unit of time). In particular, the pressure present in the respiratory tract [in cm H2O or millibar] is monitored by a pressure sensor, and the control device processes this pressure value.

[0025] The measure of the change of the first volume present at the pressure P0 is, for example, the slope of the volume-pressure curve in a volume-pressure diagram. Along one axis, the pressure is plotted, and along the other axis, the volume. The curve has a first curve section V = f ZP (P) or P = f ZV (V) and a second curve section V = f AP (P) or P = f AV (V), wherein the first curve section represents the profile / development of the volume V and the pressure P during the supply of fluid into the at least one respiratory tract, and the second curve section represents the profile / development of the volume V and the pressure P during the discharge of fluid from the at least one respiratory tract. The slope is determined by the first derivative of the respective function V = f ZP (P) (or P = f ZV (V)) and V = f AP (P) (or P = f AV (V)), i.e. df AP / d(P)(P0) and df ZP / d(P)(P0). Thus, the control device sets the ventilation process in such a way that, over at least 60% of the pressure interval, in particular over at least 80%, the ratio of the absolute value of the first slope of the first curve section at the pressure P0 (i.e. df ZP / d(P)(P0)) to the absolute value of the second slope of the second curve section at the same pressure P0 (i.e. df AP / d(P)(P0)) has a value of at least 0.5 and at most 2.0. Thus, the equation [df AP / d(P)(P0)] / [df ZPThe absolute value of the result of df ZV (V) and P = f AV (V) should be at least 0.5 and at most 2.0. In particular, P0 is thus any pressure within the pressure interval or within a 60% or 80% portion of the pressure interval. The above explanations apply analogously to the function P = f CP (V) and P = f CV (V).

[0026] The absolute value represents the numerical value of the result, i.e. the measure of the change and the slope, regardless of its mathematical sign.

[0027] In particular, it is proposed that the control device is configured for determining the distribution of the pressure P in the respiratory tract and the distribution of the volume V of fluid supplied to and discharged from the respiratory tract for the compliance of the patient from one of V = f CP (P) or P = f CV (V), wherein the ventilation process can be set in such a way that:

[0028] a) over at least 60%, in particular over at least 80%, of the pressure interval,

[0029] df AP / d(P)(P0), df ZP / d(P)(P0), each of which is divided by

[0030] - the absolute value of the measure of the first change in volume of the compliance at the pressure P0, i.e. df CP / d(P)(P0)

[0031] , or

[0032] b) over at least 60%, in particular over at least 80%, of the volume interval,

[0033] - df AV / d(V)(V0), df ZV / d(V)(V0), each of which is divided by

[0034] - the absolute value of the measure of the first change in pressure of the compliance at the volume V0, i.e. df CV / d(V)(V0)

[0035] the ratio

[0036] has a value of at least 0.5 and at most 2.0.

[0037] In particular, the ventilation process can be set in such a way that over at least 60%, in particular over at least 80%, of the pressure interval or of the volume interval, the value of the ratio is at least 0.67 and at most 1.5.

[0038] The ventilation process is preferably set in such a way that the ratio is greater than or less than 1.0, in particular greater than 1.1 or less than 0.9, over at least 60%, in particular over at least 80% of the pressure interval or volume interval.

[0039] The ventilation process is in particular set at the beginning of the fluid supply and at the beginning of the fluid discharge and at the end of the supply and at the end of the discharge in such a way that the ratio described is present there (for example over 30% or 40% of the pressure interval or volume interval from these points, whereby these ratios are present over a total of 60% or 80% of the pressure interval or volume interval, respectively).

[0040] The basic idea of the application is to ventilate the patient with as low an energy input as possible, i.e. with a low energy uptake by the respiratory tract (hereinafter also referred to as energy loss E). The lower energy input into the patient's respiratory tract also means the lowest possible damage to the patient's respiratory tract and other organs.

[0041] This minimization of the energy input (energy loss E) is achieved, inter alia, by a complete control and monitoring of the ventilation process of the fluid supply into the at least one respiratory tract and the fluid discharge from the at least one respiratory tract. Thus, in particular, the fluid supply rate and the fluid discharge rate are determined, monitored and controlled by the control device, in particular at any point in time.

[0042] This control and monitoring of the ventilation process (i.e. the fluid supply into the respiratory tract and the fluid discharge from the respiratory tract) is in particular carried out along the compliance curve of the patient's respiratory tract, which can be represented in a volume-pressure diagram. The compliance curve depicts a (minimum) pressure interval, optionally starting from a predefined PEEP or PIP, in which a predefined volume of fluid is supplied and discharged. The ventilation of the patient should at this time take place in such a way during the supply and discharge of the fluid that the volume-pressure curve of the particular ventilation process approximates the compliance curve as closely as possible. However, it has been found that further factors should also be taken into account in order to minimize the energy input. These further factors can, however, be combined individually or, of course, also (only) in combination with the respective other factors.

[0043] For the device and the method presented here, at least one, optionally multiple or even all of the following parameters (e.g. based on empirical / experimental values, patient data, compliance of the respiratory tract, resistance of the at least one respiratory tract (determinable, for example, by plethysmography), etc.) or values of the parameters are proposed or predefined for the operator of the device or by the method in which the ventilation of the patient takes place: PEEP [centimeters of water column - cm H2O or millibar], PIP [centimeters of water column - cm H2O or millibar], volume flow [milliliters per minute], ratio of the duration of the supply of fluid to the duration of the discharge of fluid from the respiratory tract - i.e. I / E (inspiration duration / exhalation duration).

[0044] In particular, a 1 : 1 ratio of I / E is proposed, wherein in particular deviations of up to 20% are possible, and wherein the expiration can also last longer, in particular up to a ratio of 1 : 1.5. In particular, when this ratio does not apply to the patient (e.g. due to illness, abnormalities, etc.), further deviations are produced.

[0045] In particular, it has been found that the first slope of the first curve section and the second slope of the second curve section of the volume-pressure curve (represented in the volume-pressure diagram) should have approximately the same value at the same pressure P0 (the pressure P0 lies within the pressure interval) within the maximum possible range of the pressure interval, respectively. The same applies to the volume V0, wherein the first slope of the first curve section and the second slope of the second curve section of the volume-pressure curve (represented in the volume-pressure diagram) should have approximately the same value at the same volume V0 (the volume V0 lies within the volume interval) within the maximum possible range of the volume interval, respectively.

[0046] The control device controls and monitors the pressure and volume curve on the one hand while supplying fluid into the at least one respiratory tract. On the other hand, the fluid is now expelled from the respiratory tract according to the profile / outline of the first curve section. In particular, passive expiration is not allowed here, which would usually result in a second curve section that is very different from the first curve section. Instead, a solution is proposed in which the fluid is actively monitored and controlled by the control device for expulsion, wherein the second curve section approximates the profile of the first curve section.

[0047] Preliminary tests using these types of ventilation devices and methods show that by this control of the ventilation, damage to the at least one respiratory tract (ventilator-induced lung injury (VILI)) can at least be reduced or even effectively prevented.

[0048] In particular, it is proposed to determine the compliance C of the at least one respiratory tract of the patient during ventilation of the respiratory tract and to consider the determined compliance for the ventilation. The distribution of at least one sub-region of the compliance curve is determined or otherwise ascertained by supplying and / or expelling fluid to / from the at least one respiratory tract and by determining at least one value of the compliance. C = AV / AP [ml / mbar or ml / cm H2O] applies to the compliance C.

[0049] The compliance represents how much fluid, i.e. a volume AV [ml], can be introduced into or removed from the respiratory tract such that the pressure in the respiratory tract changes by a pressure difference AP [mbar]. Taking into account the determined or otherwise assumed profile of the at least one sub-region of the compliance curve, the control device determines the position of the pressure interval comprising the pressures PI and P2 and sets these pressures on the ventilation device (e.g. sets PEEP to PI and PIP to P2) in such a way that at least one ventilation process, i.e. inhalation and / or exhalation, takes place between these pressures PI and P2 and that the absolute value of the compliance of this ventilation process is as large as possible.

[0050] The minimization of the energy input is achieved by determining the lowest possible pressure at which the patient can be supplied with the required breathing volume V T (tidal volume). These pressures PI and P2 of the pressure interval are determined, inter alia, on the basis of the respective compliance of the ventilated patient.

[0051] At this point it should be noted that generally two types of compliance are known, on the one hand the static compliance and on the other hand the dynamic compliance. In order to determine the static compliance, a (fixed) volume of fluid is supplied to the respiratory tract starting from the pressure PI. This state is then maintained until the pressure P2 is generated. In contrast, the dynamic compliance is determined during continuous ventilation. After the supply of a (fixed) volume of fluid, the pressure P2 occurring thereafter is immediately measured. The pressure interval PI, P2 for the dynamic compliance is therefore generally greater than or equal to the pressure interval for the static compliance. The compliance is represented as a curve in a pressure-volume diagram (or volume-pressure diagram, since the compliance is generally a ratio V / P which changes as a function of the pressure).

[0052] The profile of the compliance curve (e.g. based on empirical / experimental values) is therefore determined or otherwise assumed / assumed, in particular during at least one ventilation process (inhalation, i.e. supply of fluid to the respiratory tract, and exhalation, i.e. expulsion of fluid from the respiratory tract). In particular, it is possible to supply a given volume V (optionally V T ) in the determined minimum possible pressure interval, in particular in a sub-region of the compliance curve.

[0053] In particular, in order to determine the distribution of the compliance curve, a volume, preferably a maximum of 100 ml, particularly preferably a maximum of 50 ml, of a small volume AV of fluid is supplied to the at least one respiratory tract via the fluid supply unit. During and / or preferably after the supply of this volume, the pressure change AP in the at least one respiratory tract is measured and the value of the compliance is determined. The empirically determined value or, if appropriate, the value already determined for the compliance of this patient is then taken into account in order to at least deduce the distribution of at least a sub-region of the compliance curve. Alternatively, a further (small) volume AV is supplied and the corresponding pressure change AP is determined. From these compliance values, the distribution of at least a sub-region of the compliance curve can be determined and / or deduced (with increased accuracy). In addition, the distribution of the compliance curve and the preferred position of the pressure interval to be provided for the subsequent ventilation of the patient, which comprises the pressures PI (in particular PEEP) and P2 (in particular PIP), can be determined or deduced on the basis of a decreasing or increasing absolute value of the compliance.

[0054] V = f CP (P) applies to the pressure-volume diagram, P = f CV (V) applies to the volume-pressure diagram, wherein V = f CP (P) and P = f CV (V) represents a function describing the curve (i.e. the compliance) in the respective diagram.

[0055] In particular, at least one of the following variables can be preset or determined in advance: PEEP, respiratory rate, volume flow rate, I / E, resistance of the at least one respiratory tract, so that the required tidal volume V T can be provided at a minimum possible energy input. In addition, any of these variables can be further adjusted after the determination and deduction of the ventilation process, so that the predetermined tidal volume V T is supplied at the parameters set subsequently.

[0056] The fluid supply unit and the fluid removal unit comprise at least one (common) compressed gas source or a device which can be used to introduce fluid (for example, a gas or a gas mixture suitable for ensuring the ventilation of a patient) into the at least one respiratory tract of a patient and to remove it from the at least one respiratory tract of a patient. Preferably, there is only one compressed gas source, or the exhalation also takes place via a ventilation device (for example, the gas flow reversing device mentioned at the outset), wherein the fluid is supplied to the respiratory tract via a lumen and removed again via the same lumen.

[0057] The control device is in particular adapted to determine or otherwise to deduce the distribution of at least a sub-region of the compliance curve. The determination of the compliance curve takes place by supplying and / or removing fluid to / from the at least one respiratory tract during the ventilation and by determining at least one value of the compliance. The at least one value of the compliance can in particular be taken into account to deduce the profile of the compliance curve of the patient.

[0058] The compliance can in particular be determined at time intervals or repeatedly after a certain number of ventilations.

[0059] In particular, the control device utilizes the measured values of the at least one pressure sensor and monitors the volume flow supplied via the fluid supply unit and the volume flow discharged via the fluid discharge unit.

[0060] In particular, the pressure present in the respective respiratory tract is monitored and / or measured and determined or ascertained computationally. Thus, a pressure sensor is preferably arranged in the respiratory tract, such that continuous pressure measurement in the respiratory tract is possible, in particular even during ventilation. The pressure sensor can also be located at the fluid supply unit or the fluid discharge unit outside the respiratory tract.

[0061] This arrangement of the pressure sensor is particularly advantageous in determining the profile of the compliance curve, since in this case the (respective) changing pressure ΔΡ in the respiratory tract can be determined during the continuous or phased supply of a certain volume or partial volume of fluid.

[0062] The active control of the fluid supplied by the ventilation device during the inhalation of the lung of the patient and discharged during the exhalation from the lung of the patient preferably takes place continuously, i.e. at any point in time. This active control comprises a continuous change in the pressure of the fluid supplied and discharged by the ventilation device. The continuously changing pressure is in particular the pressure within the at least one respiratory tract and thus in particular the pressure within the lung. This pressure can be determined by a measurement by a sensor at the end of the ventilation device, such as a catheter, which reaches into the respiratory tract.

[0063] The continuous change in pressure in particular leads to a continuous control of the fluid supply rate and the fluid discharge rate [ml / s] of the fluid supplied to the lung or discharged from the lung by the ventilation device during the ventilation process. In particular, the fluid volume present in the lung (volume V) thus changes continuously. During the change in the fluid volume present in the lung, the fluid supply rate and / or the fluid discharge rate of the fluid supplied to the lung or discharged from the lung by the ventilation device preferably does not change, thus remains essentially constant. The fluid supply rate does not necessarily correspond to the fluid discharge rate, although they can also have the same absolute value. Furthermore, the fluid supply rate can change from one inhalation process to the next. The same, in particular independently thereof, applies to the fluid discharge rate during continuous exhalation.

[0064] In particular, states are avoided in which the pressure present in the lung does not change and in particular the fluid volume does not change over a certain time interval. The length of such a time interval in which the pressure present in the lung does not change and / or in particular the fluid volume does not change is preferably at most 0.5 s [seconds], in particular at most 0.2 s, preferably at most 0.1 s, and in particular only at the points in time at which the fluid flow reverses, i.e. the transition from fluid supply to fluid removal and vice versa.

[0065] The pressure is measured in particular in the patient himself, in particular advantageously in the region of the outflow from the ventilation device, i.e. from the lumen (tube / catheter) which transports the fluid into the patient's respiratory tract. Alternatively and / or additionally, the pressure is measured in the ventilation device.

[0066] In particular, the pressure in the ventilation device does not correspond to the pressure in the patient's respiratory tract. In particular, the continuous change in the pressure in the respiratory tract can also be set by at least intermittently constant pressure in the ventilation device.

[0067] The change in the pressure in the respiratory tract can be measured in particular when the fluid supply rate or the fluid removal rate is zero. This change is in particular due to the properties of the respiratory tract itself. If possible, the fluid supply rate and the fluid removal rate should be avoided to be zero (at most for a time interval of up to 0.5 seconds, in particular at most 0.2 seconds or 0.1 seconds, and then only at the points in time at which the flow of fluid reverses; if appropriate, there can be longer time intervals of up to 2.0 seconds, for example in order to carry out pressure measurements, wherein such extended time intervals are only provided at intervals of at least 30 s, in particular at least 2 minutes, preferably at least 5 minutes). For this purpose, the fluid supply rate and the fluid removal rate are in particular (only) predetermined by the ventilation device, wherein the pressure in the respiratory tract is monitored.

[0068] In particular, a sinusoidal or sawtooth-shaped breathing pattern (pressure [mbar] over time [seconds]) is thus set, in which the slope of the curve (pressure over time) is continuous and does not equal zero, and in particular only at the points in time at which the fluid flow reverses, the slope is equal to 0 for a time interval of at most 0.5 s [seconds], in particular at most 0.2 s, preferably at most 0.1 s, in particular preferably never.

[0069] In particular, a breathing pattern is predetermined for the patient at all times, preferably during ventilation by the ventilation device; i.e. the fluid supply rate (inhalation flow) and the fluid removal rate (exhalation flow) are (only) controlled and determined by the ventilation device (and not by the patient).

[0070] In particular, the fluid supply and, if appropriate, the additional fluid removal take place entirely via the ventilation device or via at least one lumen which is inserted into the patient's respiratory tract.

[0071] The continuous change of the pressure ensures that the fluid supply and the fluid discharge do not occur too fast or too slow, so that damage to the respiratory tract, in particular to the lung tissue, can be prevented or at least minimized.

[0072] Furthermore, the fluid supply and the fluid discharge can be carried out, for example, taking into account the compliance of the respiratory tract in the advantageous pressure interval, i.e. between the first, higher pressure and the second, lower pressure, and at a predefinable ventilation frequency.

[0073] With regard to the determination of the compliance and the ventilation device and the method for operating the ventilation device, reference is made to the previously unpublished DE 10 2016 109 528.1, which both relate to the compliance during ventilation.

[0074] In particular, the ventilation process can be set in such a way that:

[0075] a) the first volume present at the pressure P0 when supplying fluid and the second volume present at the same pressure P0 when discharging fluid differ at most by 30%, in particular at most by 20%, preferably at most by 10%, of the volume interval present in the pressure interval, or

[0076] b) the first pressure present at the volume V0 when supplying fluid and the second pressure present at the same volume V0 when discharging fluid differ at most by 30%, in particular at most by 20%, preferably at most by 10%, of the pressure interval present in the volume interval.

[0077] Preferably:

[0078] a) the ventilation process can be set in such a way that at least 60%, in particular at least 80%, of the pressure interval is such that the first volume present at the pressure P0 when supplying fluid and the second volume present at the same pressure P0 when discharging fluid differ at least by 1%, preferably at least by 3%, of the volume interval present in the pressure interval, or

[0079] b) the ventilation process can be set in such a way that at least 60%, in particular at least 80%, of the volume interval is such that the first pressure present at the volume V0 when supplying fluid and the second pressure present at the same volume V0 when discharging fluid differ at least by 1%, preferably at least by 3%, of the pressure interval present in the volume interval.

[0080] In particular, the control device is adapted to:

[0081] a) determine the integral of f ZP (P) and f AP (P) over the pressure interval and determine the difference between the integral of f ZP (P) dP and the integral of f APthe difference between the integrals of f

[0082] b) the difference between the integrals of f ZV (V) and f AV (V) in the volume interval. ZV (V) and the integral of f AV (V) in the volume interval.

[0083] In particular, the difference between the integrals of f Z (P) and f A (P) in the pressure interval is considered as a measure for the amount of energy absorbed by the respiratory tract. Thus, this difference between the integrals should be as small as possible so that the amount of energy absorbed by the respiratory tract can be considered as low as possible.

[0084] In particular, the control device is adapted to perform a plurality of ventilation processes, wherein

[0085] a) the difference between the integrals of f ZP (P) dP and f AP (P) dP in the pressure interval or

[0086] b) the difference between the integrals of f ZV (V) dV and f AV (V) in the volume interval

[0087] is controllable, wherein a ratio of this difference to a critical difference value established for the given patient can be set.

[0088] In particular, the critical difference value can be determined for the patient, e.g. based on empirical values or a determination of the compliance of the respiratory tract. The critical difference value refers to an amount of energy that can be supplied to the at least one respiratory tract during a ventilation process without expecting to cause harm to the at least one respiratory tract (VILI). For example, the critical difference value can be the difference between the integrals of f ZP (P) dP and f AP (P) dP in the pressure interval, wherein f ZP (P) describes the supply of fluid with as high a compliance as possible, and f AP (P) describes the discharge of fluid due to passive expiration (i.e. expiration driven by (only) energy stored in the elastic tissue elements of the lung and thorax).

[0089] In particular, the integrals of f ZP (P) dP and f AP (P) dP in the pressure interval determine the area under the first curve segment and the area under the second curve segment, respectively (the same applies to the integrals of f ZV (V) dV and f AV (V) in the volume interval). Thus, the integrals of f ZP(P)dP and ∫f AP The difference between (P)dP and ∫f ZP (P)dP and ∫f AP The difference between (P)dP and ∫f

[0090] Furthermore, a (second) ventilation device with a visualizing device is proposed, which ventilation device is adapted to ventilate a patient. The ventilation device with the visualizing device comprises at least a fluid supply unit and a fluid discharge unit, which fluid supply unit and fluid discharge unit are adapted to supply fluid into at least one respiratory tract of the patient (i.e. into the lung or lung parts) and to discharge fluid from the respiratory tract, respectively; and the ventilation device further comprises a control device, which control device is adapted to determine a profile of at least one volume-pressure curve in a volume-pressure diagram during a ventilation process of the at least one respiratory tract (i.e. by supplying fluid into the at least one respiratory tract at least once and discharging fluid from the at least one respiratory tract at least once by operating the ventilation device). The curve has a first curve section V = f ZP (P) or P = f ZV (V) and a second curve section V = f AP (P) or P = f AV (V), wherein the first curve section represents a profile of the supplied volume and pressure when supplying fluid into the at least one respiratory tract and the second curve section represents a profile of the discharged volume and pressure when discharging fluid from the at least one respiratory tract; wherein the ventilation process takes place within a pressure interval and a volume interval. The control device is adapted to determine an area in the volume-pressure diagram, which area is enclosed by the first curve section and the second curve section of the one ventilation process; wherein at least one of the following parameters can be visually discernibly displayed via the visualizing device:

[0091] a) a measure of the size of the area; or

[0092] b) a measure of the change of the area in a plurality of ventilation processes; or

[0093] c) a measure of the ratio of the area to a critical area (i.e. a critical difference of the integrals) established for the given patient; or

[0094] d) a measure of the change of the ratio of the area to a critical area (i.e. a critical difference of the integrals) established for the given patient in a plurality of ventilation processes.

[0095] In particular, in addition, the profile of at least one volume-pressure curve in the volume-pressure diagram can be displayed via the visualization device. This curve has a first curve section V = f ZP (P) or P = f ZV (V) and a second curve section V = f AP (P) or P = f AV (V), wherein the first curve section represents the profile of the volume supplied and the pressure when supplying fluid into the at least one respiratory tract, and the second curve section represents the profile of the volume discharged and the pressure when discharging fluid from the at least one respiratory tract.

[0096] In particular, the visualization device comprises a graphic display area, e.g. a monitor, via which the parameters can be displayed for reading.

[0097] In particular, the parameters explained can be shown, e.g. by a "traffic light display". The values of the parameters can be assigned to areas which can be displayed in appropriate colors (e.g. green for "non-critical"; yellow for "intermediate region"; red for "critical").

[0098] At least one of the parameters a to d is preferably displayed in relation to at least one intervention limit. An "intervention limit" is in particular a certain value of a parameter. When the intervention limit is reached, intervention or control can be required, for example. This means in particular that when a parameter reaches a certain value, an indication is provided via the visualization device so that the operator of the ventilation device or the control device itself is informed of this situation or can change the parameter, if necessary.

[0099] In addition, a (first) method for operating a (first or second) ventilation device is proposed, which ventilation device is set up for ventilating a patient, wherein the ventilation device comprises at least a fluid supply unit and a fluid discharge unit, which are adapted to supply fluid into at least one respiratory tract (i.e. lung or lung part) of the patient and to discharge fluid from the respiratory tract, respectively; and further comprises a control device. The method comprises at least the following steps:

[0100] a) carrying out a ventilation process, comprising supplying fluid into at least one respiratory tract (i.e. lung or lung part) of the patient at least once and discharging fluid from the respiratory tract at least once by operating the ventilation device; wherein the ventilation process takes place within a pressure interval and within a volume interval;

[0101] b) determining or setting, by the control device, a profile of at least one volume-pressure curve in a volume-pressure diagram during the ventilation process; wherein the curve has a first curve section V = f ZP (P) or P = f ZV (V) and a second curve section V = f AP(P) or P = f AV (V), wherein the first curve section represents the distribution of the volume V and the pressure P supplied when supplying fluid into the at least one respiratory tract, and the second curve section represents the distribution of the volume V and the pressure P discharged when discharging fluid from the at least one respiratory tract; wherein the ventilation process is set in such a way by using the control device:

[0102] (1) the ratio of the absolute value of the first slope of the first curve section, i.e. df AP / d(P) (P0), to the absolute value of the second slope of the second curve section, i.e. df AP / d(P) (P0), at the same pressure P0, has a value of at least 0.5 and at most 2.0, in particular at least 0.67 and at most 1.5, over at least 60%, in particular at least 80%, of the pressure interval, or

[0103] (2) the ratio of the absolute value of the first slope of the first curve section, i.e. df AV / d(V) (V0), to the absolute value of the second slope of the second curve section, i.e. df AV / d(V) (V0), at the same volume P0, has a value of at least 0.5 and at most 2.0, in particular at least 0.67 and at most 1.5, over at least 60%, in particular at least 80%, of the volume interval.

[0104] In particular, the ventilation process can be set in such a way that the ratio has a value of at least 0.75 and at most 1.25 over at least 60%, in particular at least 80%, of the pressure interval.

[0105] In particular, the control device determines the distribution of the volume-pressure curve in the volume-pressure diagram during the ventilation process from the compliance of the respiratory tract according to one of V = f CP (P) or P = f CV (V); wherein the ventilation process in steps a) and b) is set in such a way that, over at least 60%, in particular at least 80%, of the pressure interval, or over at least 60%, in particular at least 80%, of the volume interval,

[0106] - each df AP / d(P) (P0), df ZP / d(P) (P0) and

[0107] - the absolute value of the measure of the change of the first volume of the compliance present at the pressure P0 (11), i.e. df C / d(P) (P0)

[0108] , or

[0109] - each dfAV df / d(V)(V0), df ZV df / d(V)(V0) and

[0110] the absolute value of a measure of the change of the first pressure exhibited at the volume V0 of the compliance, i.e. df CV df / d(V)(V0)

[0111] the ratio of

[0112] has a value of at least 0.5 and at most 2.0, in particular at least 0.67 and at most 1.5, preferably at least 0.75 and at most 1.25.

[0113] In particular, in step b) or in a further step c), the control device performs the determination or setting of the area; wherein the area in the volume-pressure diagram is enclosed by the first curve section and the second curve section of one ventilation process.

[0114] In the at least one ventilation process, preferably the ratio of the area to a critical area (integrated critical difference) established for the given patient is set.

[0115] In particular, the ventilation device comprises a visualization device, wherein via the visualization device at least one of the following parameters is visually discernibly displayed:

[0116] a) a measure of the size of the area; or

[0117] b) a measure of the change of the area in a plurality of ventilation processes; or

[0118] c) a measure of the ratio of the area to a critical area (i.e. integrated critical difference) established for the given patient; or

[0119] d) a measure of the change of the ratio of the area to a critical area (i.e. integrated critical difference) established for the given patient in a plurality of ventilation processes.

[0120] In particular, the ventilation process can be set in such a way that

[0121] a) the first volume present at the pressure P0 when supplying fluid and the second volume present at the same pressure P0 when expelling fluid differ from the volume interval exhibited in the pressure interval by at most 30%, in particular at most 20%, preferably at most 10%, or

[0122] b) the first pressure present at the volume V0 when supplying fluid and the second pressure present at the same volume V0 when expelling fluid differ from the pressure interval present in the volume interval by at most 30%, in particular at most 20%, preferably at most 10%.

[0123] The explanations regarding the ventilation device and the ventilation device with a visualization device are equally applicable to the proposed method and vice versa.

[0124] In particular, a (second) method for operating the (above-described) ventilation device is proposed. The ventilation device is provided for ventilating a patient. The method comprises at least the following steps:

[0125] i. supplying and / or discharging fluid into and / or from at least one respiratory tract (i.e. lung or lung part) of the patient by operating the ventilation device;

[0126] ii. determining or otherwise inferring a distribution of at least one sub-region of a compliance curve of the at least one respiratory tract by the fluid supply and / or discharge in step i. and determining at least one value of the compliance, wherein the following applies to the compliance C:

[0127] C = ΔV / ΔP [ml / mbar];

[0128] wherein the compliance indicates how much fluid (i.e. volume ΔV [ml]) is introduced into the at least one respiratory tract or removed from the respiratory tract so that the pressure in the respiratory tract changes by a pressure difference ΔP [mbar];

[0129] iii. determining the position of a pressure interval with pressures P1 and P2 along the distribution of at least one sub-region of the compliance curve determined or otherwise inferred in step ii., wherein the absolute value of the compliance is as large as possible for a ventilation process (i.e. inhalation and / or exhalation) carried out in the pressure interval;

[0130] iv. supplying and / or discharging fluid in the pressure interval determined in step iii. in at least one ventilation process after step iii.

[0131] In particular, the method with steps i. to iv. is additionally performed with respect to the method with steps a) and b) and optionally simultaneously or with a time delay. In particular, the compliance of the respiratory tract can be determined during the fluid supply and the supply and discharge of fluid for at least one ventilation process is carried out in accordance with steps a) and b) of the method.

[0132] A method for ventilating a patient with as low an energy input as possible is thus proposed. By determining the lowest possible pressure with which the required breathing volume V T (tidal volume) can be supplied to the patient, a minimization of the energy input is also achieved. These pressures P1 and P2 of the pressure interval can be determined, for example, on the basis of the respective compliance of the patient being ventilated.

[0133] In particular, in step ii, a plurality of compliance values is determined at least during inspiration or expiration of a ventilation process, so that in step iii the position of a pressure interval comprising the pressures P1 and P2 can be determined for at least one subsequent ventilation process, for which the absolute value of the compliance is as large as possible. In particular, the control device determines the compliance values continuously or at predetermined time intervals. Preferably, at least 5, in particular preferably at least 10 compliance values are determined for each ventilation process.

[0134] Steps ii, iii and iv are preferably performed continuously, so that for each subsequent ventilation process or a plurality of successive ventilation processes, the position of the pressure interval is selectively re-determined with the pressures P1 and P2.

[0135] According to one preferred embodiment, at least for the subsequent ventilation process, at least one of the following parameters is determined from the position of the pressure interval and the pressure interval itself determined in step iii and the compliance determined therefrom:

[0136] - the respiratory volume V T (tidal volume) [ml],

[0137] - the pressures P1 (e.g. PEEP) and P2 (e.g. PIP) [mbar],

[0138] - the ventilation frequency F [1 / s]

[0139] - the I / E.

[0140] According to one advantageous embodiment, at least the pressure rise during inspiration (i.e. ΔP / Δt [mbar / s]) is monitored and limited.

[0141] According to another advantageous embodiment, at least the pressure drop during expiration (i.e. ΔP / Δt [mbar / s]) is monitored and limited.

[0142] Preferably, both the pressure rise and the pressure drop are monitored and limited.

[0143] In particular, the absolute value of the pressure rise or the pressure drop is limited to at most 40 mbar / s [mbar / s], in particular at most 30 mbar / s, preferably at most 20 mbar / s, in particular preferably at most 10 mbar / s.

[0144] In particular, the patient is ventilated using a catheter having a cross-section of at most 30 mm 2 [square millimeters], in particular at most 20 mm 2 for the at least one fluid supplied during inspiration.

[0145] In particular, with this smaller cross-section (inspiration and expiration only via the lumen), the pressure rise can be limited during inspiration as well as during expiration.

[0146] In particular, a resistance (e.g. flow resistance, etc.) can be provided in the fluid discharge unit, which limits and controls the pressure drop during expiration.

[0147] For the proposed ventilation device and the described method, in particular, the case is that a sub-region of the compliance curve presented for at least one airway of the patient to be ventilated is first determined and, if appropriate, is additionally assumed. For this purpose, the pressure rise during the delivery of a defined volume V (e.g. 50 or 100 ml; optionally also V T ) is measured.

[0148] In addition, in particular, the PEEP level (i.e. the lower pressure in P1 and P2) is subsequently determined. For determining the PEEP level with which the patient is subsequently ventilated, initially also a plurality of ventilation processes with different PEEP levels, respectively, can be carried out.

[0149] In addition, the PIP level (i.e. the higher pressure in P1 and P2) is preferably determined. For determining the PIP level with which the patient is subsequently ventilated, initially also a plurality of ventilation processes with different PIP levels, respectively, can be carried out.

[0150] In addition, a tidal volume V T is set for the patient in question. This tidal volume V T can be further adjusted during ventilation, for example based on monitoring of the CO2 level. Alternatively or additionally, the CO2 level can also be influenced by the frequency or the volume flow rate of the ventilation process.

[0151] In particular, the pressure rise and / or the pressure drop is controlled and monitored during ventilation, such that the shear stress and the energy input acting on the at least one airway is minimized.

[0152] In particular, the ventilation device and / or the method ensures that the absolute value of the compliance is as large as possible during the ventilation process, or in other words, in particular:

[0153] (1) the ventilation is carried out within a pressure interval in which the supplied fluid volume is at a maximum, or

[0154] (2) the supply or discharge of a predetermined volume V or tidal volume V T of fluid is carried out within a pressure interval that is as small as possible.

[0155] The application also relates to a further (third) method for ventilating a patient and / or for operating a ventilation device, in particular the above-mentioned ventilation device. The ventilation device is arranged for ventilating a patient.

[0156] The (third) method is again directed at the ventilation of a patient, wherein the lowest possible energy input into the patient's respiratory tract is to be achieved. According to the method, the fluid supplied by the ventilation device during the inspiration of the patient's lungs and the fluid discharged during the expiration from the patient's lungs is actively and continuously (i.e. at any point in time) controlled during the ventilation of the patient. This active control comprises a continuous change of the pressure of the supplied and discharged fluid by the ventilation device. This continuously changed pressure is in particular the pressure within the respiratory tract and thus within the lungs. The pressure can be determined by a sensor via a measurement at the end of the ventilation device (e.g. catheter), which reaches into the respiratory tract.

[0157] The continuous change of the pressure in particular leads to a continuous control of the fluid supply rate or the fluid discharge rate [ml / s] from the lungs by the ventilation device during the ventilation process. In particular, the fluid volume V present in the lungs is thus continuously changed. During the change of the fluid volume present in the lungs, the fluid supply rate and / or the fluid discharge rate from the lungs by the ventilation device is preferably not changed, thus remains essentially constant. The fluid supply rate does not necessarily have to correspond to the fluid discharge rate, although it can also have the same size. Furthermore, the fluid supply rate can vary from one inspiration process to the next. The same (in particular independently thereof) applies to the fluid discharge rate during the continuous expiration process.

[0158] In particular, a state is avoided in which the pressure present in the lungs does not change and in particular the fluid volume does not change over a period of time. Preferably, the length of such a time interval in which the pressure present in the lungs does not change and / or in particular the fluid volume does not change is at most 0.5 s [seconds], in particular at most 0.2 s, preferably at most 0.1 s, in particular (only) at the point in time at which the fluid flow reverses (i.e. the transition from fluid supply to fluid discharge, and vice versa).

[0159] The application relates to a further (third) ventilation device for ventilating a patient. The ventilation device comprises at least a fluid supply unit and a fluid discharge unit, which are each adapted to supply fluid into at least one respiratory tract (i.e. lung or lung part) of a patient and to discharge fluid from the respiratory tract; and further comprises a control device, which is configured to control the fluid supply and the fluid discharge during a ventilation process (i.e. at least one supply of fluid into the at least one respiratory tract and at least one discharge of fluid from the at least one respiratory tract by operating the ventilation device) of the at least one respiratory tract at least according to V = f ZP (P) and V = fAP (P) or according to P = f ZV (V) and P = f AV (V) to set a distribution of the pressure P in the respiratory tract and a distribution of the volume V of fluid supplied to and discharged from the respiratory tract. The ventilation process takes place within a pressure interval and a volume interval; wherein, by using the control device, the ventilation process can be set in such a way that the volume flow rate F(t) [l / min] (optionally varying over time) at most varies by 50%, in particular at most by 25%, relative to the average volume flow rate FD during the ventilation process within at least 80%, preferably 90%, of the duration of the ventilation process when supplying fluid and discharging fluid.

[0160] The volume flow rate F(t) can in particular vary over time, wherein in particular a (preferred) constant volume flow rate F(t) (based on the absolute value) should be set. The average volume flow rate FD is determined by dividing the sum of the supplied and discharged fluid (i.e. always positive) by the duration of the ventilation process. In order to set and control the volume flow rate F(t), the average volume flow rate can also be determined on the basis of a previous ventilation process or on the basis of preset parameters (e.g. frequency and tidal volume).

[0161] It has been found within the scope of the present application that in particular the difference of the volume flow rate F(t) also influences the energy absorbed by the respiratory tract.

[0162] The present application relates to a further (fourth) ventilation device for ventilating a patient. The ventilation device with a visualization device comprises at least a fluid supply unit and a fluid discharge unit, which are adapted to supply fluid into at least one respiratory tract (i.e. lung or lung part) of a patient and to discharge fluid from the respiratory tract, respectively; and further comprises a control device, which is adapted to determine and set a volume flow rate F(t) [l / min] of the fluid at least during a ventilation process (i.e. supplying fluid into the at least one respiratory tract and discharging fluid from the at least one respiratory tract at least once by operating the ventilation device) of the at least one respiratory tract. The ventilation process takes place within a pressure interval and a volume interval; wherein, assuming a respiratory tract resistance R of the respiratory tract of the patient, the control device is adapted to determine a power loss PW(t) [Watt] of the respiratory tract according to PW(t) = R1*(F(t)) 3 + R2*(F(t)) 2 wherein R1 = R [Pa / (m 3 / s) 2 ] and R2 = R [Pa / (m 3 / s)] (wherein the units are [Pa / (m 2]) and [Pascal / (cubic meter / second)]; wherein at least one of the following parameters can be visually discernibly displayed via the visualisation device:

[0163] a) the power loss PW(t); or

[0164] b) the energy loss E [Joule] over a period of time, i.e. PW(t) d t the integral, i.e. ∫PW(t)dt; or

[0165] c) a measure of the ratio of the power loss PW(t) to a critical power loss established for the given patient; or

[0166] d) a measure of the ratio of the energy loss E to a critical energy loss established for the given patient.

[0167] The energy loss as described herein refers to the energy in the input respiratory tract as mentioned at the outset. The aim is to minimise this energy loss. As described above, the respiratory tract resistance R can be determined by, for example, plethysmography.

[0168] In particular, the visualisation device comprises a graphic display area, for example a monitor, via which the parameters can be displayed for reading off.

[0169] In particular, the parameters can be shown, for example, by a "traffic light display". The values of the parameters can be assigned to areas which can be displayed in suitable colours (for example, green for "non-critical"; yellow for "intermediate region"; red for "critical").

[0170] At least one of the parameters a to d is preferably able to be displayed in relation to at least one intervention limit. An "intervention limit" is in particular a certain value of the parameter; when the intervention limit is reached, an intervention or control can be required, for example. This means in particular that when the parameter reaches a certain value, an indication is provided via the visualisation device in order to inform the operator of the ventilation device or the control device itself of this situation, or the parameter can be changed if necessary.

[0171] The present invention relates to a (fourth) method for operating a ventilation device. The ventilation device is set up for ventilating a patient, wherein the ventilation device comprises at least a fluid supply unit and a fluid discharge unit, which are adapted to supply and discharge fluid, respectively, into and from at least one respiratory tract (i.e. lung or lung part) of the patient; and further comprises a control device. The method comprises at least the following steps:

[0172] a) performing a ventilation process comprising at least one supply of fluid into at least one respiratory tract (i.e. lung or lung part) of a patient and at least one discharge of fluid from the respiratory tract by operating a ventilation device; wherein the ventilation process takes place within a pressure interval and within a volume interval;

[0173] b) determining or setting the distribution of the pressure P in the respiratory tract and the distribution of the volume V of fluid supplied to and discharged from the respiratory tract according to V = f ZP (P) and V = f AP (P) or according to P = f ZV (V) and P = f AV (V); wherein, by using the control device, the ventilation process can be set in such a way that the volume flow rate F(t) [l / min] varies at most 50%, in particular at most 25%, with respect to the average volume flow rate FD in the ventilation process within at least 80%, preferably 90%, of the duration of the ventilation process when supplying fluid and discharging fluid.

[0174] In particular, the ventilation device comprises a visualization device, wherein at least one of the following parameters is visually discernibly displayed via the visualization device:

[0175] a. the power loss PW(t); or

[0176] b. the energy loss E [Joule] over a period of time, i.e. the integral of PW(t)dt, i.e. ∫PW(t)dt; or

[0177] c. a measure of the ratio of the power loss PW(t) to a critical power loss established for the particular patient; or

[0178] d. a measure of the ratio of the energy loss E to a critical energy loss established for the given patient.

[0179] The present invention relates to a further (fifth) ventilation device for ventilating a patient. The ventilation device comprises at least a fluid supply unit and a fluid discharge unit, which are adapted to supply fluid into at least one respiratory tract (i.e. lung or lung part) of a patient and to discharge fluid from the respiratory tract, respectively; and further comprises a control device configured for determining or setting the distribution of the pressure P in the respiratory tract and the distribution of the volume V of fluid supplied to and discharged from the respiratory tract according to V = f ZP (P) and V = f AP (P) or according to P = f ZV (V) and P = f AV(V) to set the profile of the pressure P in the respiratory tract and the profile of the volume V of fluid supplied to and discharged from the respiratory tract, wherein the ventilation process takes place within a pressure interval and within a volume interval. By using the control device, the ventilation process can be set in such a way that the square of the speed of the profile of the pressure P [cm H20] and the volume V [ml] when supplying and discharging fluid 2 (i.e. (s(t)) 2 = (dP / dt) 2 + (dV / dt )2 ) varies at most by 300%, preferably at most by 200% from the average square of the speed SD 2 during the ventilation process over at least 80%, preferably 90% of the duration of the ventilation process.

[0180] Within the scope of the application, it has been found that the power loss P(t) is proportional to the square of the speed (s(t)) 2 of the profile of the pressure P [cm H20] and the volume V [ml] when supplying and discharging fluid as described here.

[0181] Thus, in this case, the square of the speed (s(t)) 2 is determined, which can in particular be calculated via the control of the ventilation device.

[0182] The square of the speed (s(t)) 2 may in particular vary over time. However, a (preferably) constant speed s(t) should in particular be set. The average square of the speed sD 2 is determined according to sD 2 = (ΔP / t) 2 + (ΔV / t) 2 , wherein ΔP is the pressure interval of the ventilation process, ΔV is the volume interval of the ventilation process and t is the duration of the ventilation process. In order to set and control the ventilation process at a given point in time, the average square of the speed can also be determined on the basis of previous ventilation processes or on the basis of preset parameters (e.g. volume flow rate, PEEP and PIP and V T and frequency).

[0183] This invention relates to yet another (sixth) ventilation device for ventilating a patient. The ventilation device, having a visualization device, includes at least a fluid supply unit and a fluid discharge unit adapted to supply fluid to at least one airway of the patient (i.e., a lung component or lung) and to discharge fluid from that airway, respectively; and further includes a control device adapted to determine the distribution of at least one volume-pressure curve in a volume-pressure graph during at least one ventilation process of the at least one airway (i.e., by operating the ventilation device to supply fluid to and discharge fluid from the at least one airway at least once); wherein the curve has a first curve segment V = f ZP (P) or P = f ZV (V) and the second curve segment V = f AP (P) or P = f AV (V), where the first curve segment represents the distribution of supply volume V and pressure P when fluid is supplied to the at least one respiratory tract, and the second curve segment represents the distribution of discharge volume V and pressure P when fluid is discharged from the at least one respiratory tract; wherein the gas exchange process occurs within the pressure and volume ranges. The control device is adapted to determine the square of the rate (s(t)) of pressure P [cmH2O] and volume V [ml] during fluid supply and discharge. 2 That is, (s(t)) 2 =(dP / dt) 2 +(dV / dt) 2 At least one of the following parameters can be visually distinguishable via a visualization device:

[0184] a) The square of the velocity s(t), i.e., (s(t)) 2 ;or

[0185] b) Over a period of time (s(t)) 2 The integral of dt, i.e., ∫(s(t)) 2 dt; or

[0186] c) The square of the velocity (s(t)) 2 A measure of the ratio to the square of the critical velocity established for a given patient; or

[0187] d)(s(t)) 2 A measure of the ratio of the integral of dt to the critical value of that variable established for a given patient.

[0188] Specifically, the visualization device includes a graphical display area, such as a monitor, through which the parameters can be displayed for reading.

[0189] In particular, the parameters can be displayed, for example, by a "traffic light display". The values of the parameters can be assigned to areas which can be displayed in suitable colors (for example, green for "non-critical"; yellow for "intermediate region"; red for "critical").

[0190] At least one of the parameters a to d is preferably displayable relative to at least one intervention limit. An "intervention limit" is in particular a certain value of a parameter; when the intervention limit is reached, intervention or control can be required, for example. This means in particular that when a parameter reaches a certain value, an indication is provided via the visualization device so that the operator of the ventilation device or the control device itself is informed of this situation or can change the parameter, if necessary.

[0191] The present application relates to a (fifth) method for operating a ventilation device. The ventilation device is set up for ventilating a patient, wherein the ventilation device comprises at least a fluid supply unit and a fluid removal unit, which are adapted to supply fluid into at least one respiratory tract (i.e. lung component or lung) of the patient and to remove fluid from the respiratory tract, respectively; and further comprises a control device. The method comprises at least the following steps:

[0192] a) carrying out a ventilation process, comprising supplying fluid into at least one respiratory tract (i.e. lung or lung component) of the patient at least once and removing fluid from the respiratory tract at least once by operating the ventilation device; wherein the ventilation process takes place within a pressure interval and within a volume interval;

[0193] b) determining or setting a profile of at least one volume-pressure curve in a volume-pressure diagram by the control device during the ventilation process; wherein the curve has a first curve section V = f ZP (P) or P = f ZV (V), and a second curve section V = f AP (P) or P = f AV (V), wherein the first curve section represents a profile of the supplied volume V and the pressure P when fluid is supplied into the at least one respiratory tract, and the second curve section represents a profile of the removed volume V and the pressure P when fluid is removed from the at least one respiratory tract; wherein, by using the control device, the ventilation process can be set in such a way that the square of the velocity of the profile of the pressure P [cm H2O] and the volume V [ml] 2 , i.e. s(t) 2 = (dP / dt) 2 + (dV / dt) 2 , varies by at most 300%, preferably by at most 200%, from the average square SD 2 of the velocity during the ventilation process over at least 80%, preferably 90%, of the duration of the ventilation process.

[0194] In particular, the ventilation device comprises a visualization device; wherein at least one of the following parameters is displayed in a visually discernible manner via the visualization device:

[0195] a) the square of the velocity s(t), i.e. (s(t)) 2 ; or

[0196] b) the integral of (s(t)) dt over a period of time, i.e. ∫(s(t)) dt; or 2 2 c) a measure of the ratio of the square of the velocity to a critical velocity square (33) established for the given patient; or

[0197] d) a measure of the ratio of the integral of (s(t)) dt to a critical value of this variable (34) established for the given patient.

[0198] 2

[0199] The explanations regarding the ventilation devices (all, i.e. from the first ventilation device to the sixth ventilation device) and the methods (all, i.e. from the first method to the fifth method) are respectively transferable to the respective other subject matter of the present application. In particular, the parameters and conditions can be combined with each other for the ventilation devices and methods. In particular, at least one or some (or even all) of the parameters and conditions form a (joint) condition for the ventilation process (or the ventilation method, which continues to a plurality of consecutive ventilation processes). In particular, the ventilation process should therefore be carried out in such a way that it corresponds to all the embodiments described for the different ventilation devices or methods.

[0200] It should be expressly noted that the control device can also be protected independently of the ventilation device. The control device serves, inter alia, to regulate the ventilation process. It establishes which variables are used to control the ventilation process and which parameters are monitored thereby (maximum / minimum pressure, maximum / minimum volume flow, slope of the first and second curve sections, area, difference between areas, etc.).

[0201] As a precaution, it should be noted that the ordinal numbers used here ("first", "second", "third"...) are used primarily (only) to distinguish a plurality of similar objects, variables or processes; i.e. in particular, a dependency and / or an order of these objects, variables or processes relative to each other is not necessarily indicated. If a dependency and / or an order is necessary, this will be expressly indicated in the text or will be apparent to the skilled person researching the specific described embodiment. BRIEF DESCRIPTION OF DRAWINGS

[0202] ​​​The application and the technical field are explained in more detail below with reference to the drawings. It is pointed out that the drawings show one particularly preferred embodiment variant of the application, but the application is not restricted to this variant. In the drawings, identical parts are denoted by the same reference numerals. In the drawings, respectively:

[0203] Figure 1 : a ventilation device and a patient are shown;

[0204] Figure 2 : a distribution of a compliance curve is shown;

[0205] Figure 3 : a first illustration of a ventilation process is shown in a volume-pressure diagram;

[0206] Figure 4 : a second illustration of a ventilation process is shown in a volume-pressure diagram;

[0207] Figure 5 : a first graph is shown, in which a volume flow rate is plotted against time;

[0208] Figure 6 : a second graph is shown, in which a volume flow rate is plotted against time;

[0209] Figure 7 : a third graph is shown, in which a square of a velocity is plotted against time; and

[0210] Figure 8 : a fourth graph is shown, in which a square of a velocity is plotted against time. DETAILED DESCRIPTION

[0211] Figure 1 A ventilation device 1 and a patient having at least one respiratory tract 5, i.e. lungs, are shown. The ventilation device 1 comprises a fluid supply unit 2 and a fluid discharge unit 3, which are adapted to supply fluid 4 into the respiratory tract 5 of the patient, i.e. into the lungs or lung parts, and to discharge fluid 4 from the respiratory tract 5, respectively. The ventilation device 1 further comprises a control device 6, which is adapted to set a distribution of a pressure P 7 in the respiratory tract 5 and a distribution of a volume V 8 of the fluid 4 supplied to and discharged from the respiratory tract 5 during a ventilation process of the at least one respiratory tract 5 of the patient, i.e. by operating the ventilation device 1 to supply fluid 4 into the at least one respiratory tract 5 and / or to discharge fluid from the at least one respiratory tract 5, in accordance with V = f ZP (P) and V = f AP (P) during the ventilation process. The ventilation device 1 is connected to the respiratory tract 5 of the patient via a catheter 40 of a lumen, which has a lumen cross section 41, through which the fluid 4 can flow. Thus, the ventilation is performed, for example, via a single lumen, in particular using a gas flow reversing device.

[0212] The ventilation device 1 has a visualizing device 17, via which at least one of the following parameters can be displayed in a visually discernible manner: a measure of the size of the area 20; or a measure of the change in the area 20 over a plurality of ventilation processes; or a measure of the ratio of the area 20 to a critical area 21 established for the given patient; or a measure of the change in the ratio of the area 20 to a critical area 21 established for the given patient over a plurality of ventilation processes.

[0213] The pressure sensor 39 is located on a catheter 40 within the respiratory tract 5. The respiratory tract 5 has a compliance C 25.

[0214] Figure 2 The distribution of the compliance curve 35 in a pressure-volume diagram is shown. The pressure 7 is plotted on the horizontal axis, while the volume 8 is plotted on the vertical axis. The distribution of the compliance curve 35 will be determined separately for each patient. In addition, the distribution can also change during ventilation.

[0215] At least one value of the compliance 25 is initially determined in the context of the method, i.e. by the ventilation device 1, wherein the following applies to the compliance C 25: C = Δ volume V 8 / Δ P 7 in milliliter / millibar. In the subregion of the compliance curve shown here, the absolute value of the compliance 25 is at a maximum. By determining or inferring the distribution of the compliance curve 25, it is possible to determine the position of the pressure interval 9, which comprises the pressures P1 36 and P2 37, in which the tidal volume V T 38 of the fluid 4 can be supplied to the at least one respiratory tract 5. These pressures P1 36 and P2 37 are set in the ventilation device 1 such that the at least one ventilation process, i.e. the inhalation and / or the exhalation, takes place in such a way that in each case the tidal volume V T 38 is between these pressures P1 36 and P2 37.

[0216] Figure 3 A first illustration of the ventilation process is shown in a volume-pressure diagram. The pressure 7 is plotted on the horizontal axis, while the volume 8 is plotted on the vertical axis. The illustrated volume-pressure curve shows the distribution of the pressure P 7 in the respiratory tract 5 when the volume V 8 in the respiratory tract 5 changes by the tidal volume V T 38, i.e. on the one hand the supply volume V 8 of the fluid 4 and on the other hand the discharge volume V 8 of the fluid 4. The curve has a first curve section 18: V = f ZP (P) extending from the lowest pressure 7 and the minimum volume 8 to the highest pressure 7 and the maximum volume 8 and a second curve section 19: V = f AP(P) (top curve extending from the maximum pressure 7 and the maximum volume 8 to the minimum pressure 7 and the minimum volume 8 adjacent to the first curve section 18), wherein the first curve section 18 represents the distribution of the volume V 8 (tidal volume V T 38) and the pressure P 7 supplied when the fluid 4 is supplied into the at least one respiratory tract 5, while the second curve section 19 represents the distribution of the volume V 8 (tidal volume V T 38) and the pressure P 7 expelled when the fluid 4 is expelled from the at least one respiratory tract 5.

[0217] A measure of the change of the first volume 12 present at the pressure P0 11 is, for example, the first slope 23 of the volume-pressure curve (in this case the first curve section 18) in the volume-pressure diagram. The slopes (first slope 23 and second slope 24) are determined by the first derivative of the respective functions V = f ZP (P) and V = f AP (P) at the pressure P0 11, i.e. df AP / d(P) (P0) and df ZP / d(P) (P0).

[0218] It has been found that the first slope 23 of the first curve section 18 of the volume-pressure curve representable in the volume-pressure diagram at the pressure P0 11 and the second slope 24 of the second curve section 19 at the same pressure P0 11, respectively, i.e. a measure of the absolute value of the change of the second volume 13 present at the same pressure P0 11 during the expulsion of the fluid 4, should have approximately the same value within the maximum possible range of the pressure interval 9.

[0219] The control device 6 controls and monitors the pressure profile and the volume profile on the one hand during the supply of the fluid 4 into the at least one respiratory tract 5. On the other hand, the expulsion of the fluid 4 from the respiratory tract 5 is now also controlled and monitored in accordance with the profile of this first curve section 18. In particular, passive exhalation is not allowed here (see Figure 3 ), which would normally result in a second curve section 19 that is very different from the first curve section 18 and thus a larger area 20. Rather, it is proposed that the control device 6 also actively monitors and controls the expulsion of the fluid 4, wherein the second curve section 19 approximates the profile of the first curve section 18 (see Figure 4 ).

[0220] Preliminary tests using these types of ventilation devices and methods have shown that by this ventilation control it is possible to at least reduce or even effectively prevent damage to the at least one respiratory tract 5 (ventilator-induced lung injury (VILI)).

[0221] The control device 6 is adapted to determine the integral fZP (P) and f AP (P) and determining the difference between the integrals of f ZP (P) dP and f AP (P) dP.

[0222] The control device 6 is adapted to perform a plurality of ventilation processes in which the difference between the integrals of f ZP (P) dP and f AP (P) dP in the pressure interval 9 is controllable, wherein a ratio of the difference to a critical difference value established for a given patient can be set.

[0223] The area under the first curve section 18 and the area under the second curve section 19 are determined by the integrals of f ZP (P) and f AP (P) in the pressure interval 9, i.e. by f ZP (P) dP and f AP (P) dP, respectively. Thus, the difference between the integrals of f ZP (P) and f AP (P) in the pressure interval 9 represents the area 20 enclosed by the first curve section 18 and the second curve section 19. The difference between the integrals of f ZP (P) and f AP (P) in the pressure interval 9 and thus the area 20 enclosed by the curve sections 18, 19 is considered a measure for the energy E absorbed by the respiratory tract 5. Thus, the difference between the integrals, i.e. the area 20, should be as small as possible in order for the energy E absorbed by the respiratory tract 5 to be as low as possible. Figure 4 A ventilation process set in this way is shown.

[0224] In particular, a critical difference value, i.e. a critical area 21, can be determined for a patient based on, for example, empirical values or a determination of the compliance 25 of the respiratory tract 5. The critical difference value or critical area 21 refers to an amount of energy E that can be supplied to the at least one respiratory tract 5 during a ventilation process without expecting damage (VILI) to the at least one respiratory tract 5. The critical difference value can be, for example, the difference between the integrals of f ZP (P) and f AP (P) in the pressure interval 9, wherein f ZP (P), i.e. the first curve section 18 in the graph according to Figure 3 describes the supply of fluid 4 with as high a compliance 25 as possible, and wherein f AP (P), i.e. the second curve section 19 in the graph according to Figure 3 describes the discharge of fluid 4 due to passive expiration, i.e. expiration driven by (only) energy stored in the elastic tissue elements of the lungs and the chest. Thus,Figure 3 The critical difference in the critical area 21 between the curve sections 18, 19.

[0225] Figure 4 A second illustration of the ventilation process in a volume-pressure diagram is shown. Reference is made to the description of Fig. 1. Figure 3

[0226] The control device 6 is configured for setting the profile of the pressure P 7 in the respiratory tract 5 and the profile of the volume V 8 of the fluid 4 supplied to and discharged from the respiratory tract 5 in dependence on V = f ZP (P) and V = f AP (P) at least during one of the illustrated ventilation processes (i.e. at least one supply of the fluid 4 into the at least one respiratory tract 5 and at least one discharge of the fluid 4 from the at least one respiratory tract 5) by operating the ventilation device 1. The ventilation process takes place within the pressure interval 9. By using the control device 6, the ventilation process can be set in such a way that the ratio of the absolute value of the measure of the change of the first volume 12 present during the supply of the fluid 4 at the pressure P0 11 (i.e. df AP / d(P)(P0)) to the absolute value of the measure of the change of the second volume 13 present during the discharge of the fluid 4 at the same pressure P0 11 (i.e. df ZP / d(P)(P0)) at the pressure P0 11 (second slope 24 of the second curve section 19) has a value of at least 0.5 and at most 2.0 over at least 60% of the pressure interval 9.

[0227] This applies correspondingly to each volume V0 14 (not shown here), wherein the ratio of the absolute value of the measure of the change of the first pressure 15 present during the supply of the fluid 4 at the volume V0 14 (i.e. df AV / d(V)(V0)) to the absolute value of the measure of the change of the second pressure 16 present during the discharge of the fluid 4 at the same volume V0 14 (i.e. df ZV / d(V)(V0)) has a value of at least 0.5 and at most 2.0 over at least 60% of the volume interval 10.

[0228] In this case, by using the control device 6, the ventilation process is set in such a way that the ratio of the absolute value of the first slope of the first curve section 18 at the pressure P0 11 (i.e. df AP / d(P)(P0)) to the absolute value of the second slope 24 of the second curve section 19 at the same pressure P0 11 (i.e. df ZP / d(P)(P0)) has a value of at least 0.5 and at most 2.0 over at least a part of the pressure interval 9. Accordingly, the algebraic expression [df​AP | df ZP The absolute value of the result of the division of df

[0229] The ventilation process is here further set in such a way that the first volume 12 present during the supply of fluid 4 at the pressure P011 and the second volume 13 present during the discharge of fluid 4 at the same pressure P011 differ at most by 20% of the supplied or discharged volume 8 in the pressure interval 9.

[0230] The ventilation process is here further set in such a way that the first volume 12 present during the supply of fluid 4 at the pressure P011 and the second volume 13 present during the discharge of fluid 4 at the same pressure P011 differ at least by 1% of the (total) supplied or discharged volume 8 (in this case the tidal volume V T 38) in the pressure interval.

[0231] At least one or some of the following parameters can be visually displayed via the visualization device 17: a measure of the size of the area 20; a measure of the change of the area 20 in the plurality of ventilation processes; a measure of the ratio of the area 20 to the critical area 21 established for the given patient (i.e. the integrated critical difference); a measure of the change of the ratio of the area 20 to the critical area 21 established for the given patient (i.e. the integrated critical difference) in the plurality of ventilation processes. In addition, by using the visualization device 17 and based on, for example, a display of the ventilation processes in the volume-pressure diagram according to Figure 3 or Figure 4 The slopes 23, 24 of the curve sections 18, 19 can be set or changed by the control device 6 or by an operator of the ventilation device 1 by using a display of the ventilation processes in the volume-pressure diagram according to

[0232] Figure 4 It is further shown that the control device 6 is configured for determining the distribution of the pressure P 7 in the respiratory tract 5 and the distribution of the volume V 8 of the fluid 4 supplied to and discharged from the respiratory tract 5 for the compliance 25 of the patient according to one of V = f CP (P) or P = f CV (V). The first curve section 18 corresponds here to the compliance 25. The ventilation process can be set by the control device 6 in such a way that df AP / d(P)(P0) (in this case the second slope 24 of the second curve section 19) and df ZPthe absolute value of the ratio of each of / d(P)(P0) (in this case the first slope 23 of the first curve section 18) to a measure of the change of the first volume 12 of compliance 25 present at the pressure P011 (i.e. df CP The value of the ratio of each of / d(P)(P0) to a measure of the change of the first volume 12 of compliance 25 present at the pressure P011 is at least 0.5 and at most 2.0.

[0233] Figure 5 A first graph is shown, in which the volume flow rate 26 is plotted against time 44. Figure 6 A second graph is shown, in which the volume flow rate 26 is plotted against time 44. In the following discussion, the first and second graphs are described together Figure 5 and 6 .

[0234] As mentioned above, the control device 6 is configured for setting the profile of the pressure P 7 in the respiratory tract 5 and the profile of the volume V 8 of fluid 4 supplied to and discharged from the respiratory tract 5 according to V = f ZP (P) and V = f AP (P) or according to P = f ZV (V) and P = f AV (V), wherein the ventilation process takes place within the pressure interval 9 and within the volume interval 10. Figure 5 The volume flow rate F(t) 26 of the ventilation process according to Figure 3 is shown. Figure 6 The volume flow rate F(t) 26 of the ventilation process according to Figure 4 is shown. By using the control device 6, it is now possible to set the ventilation process (see Figure 6 in such a way that the volume flow rate F(t) 26 [l / min] (here shown with different mathematical signs, thus plotted as 0 l / min relative to the zero line) varies by at most 50% relative to the average volume flow rate FD 42 in the ventilation process over at least 80% of the duration of the ventilation process when supplying and discharging fluid 4. It is clear that the volume flow rate F(t) 26 varies over time 44, wherein in particular a (preferably) constant volume flow rate F(t) 26 (based on the absolute value) should be set. The average volume flow rate FD 43 is determined by dividing the sum of the supplied and discharged fluid 4 (i.e. always positive) by the duration of the ventilation process (i.e. the time 43 between the origin and the vertical line in the graph). In order to set and control the volume flow rate F(t) 26, the average volume flow rate FD 43 can also be determined on the basis of a previous ventilation process or on the basis of preset parameters (e.g. frequency and tidal volume 38).

[0235] Figure 7 A third graph is shown, in which the square of the velocity is shown against time 44. Figure 8The fourth figure is shown, which illustrates the square of the velocity relative to time 44. This will be described together in the discussion below. Figure 7 and 8 .

[0236] As described above, the control device 6 is configured to operate according to V = f ZP (P) and V = f AP (P) or according to P = f ZV (V) and P = f AV (V) is used to set the distribution of pressure P 7 in the respiratory tract 5 and the distribution of volume V 8 of fluid 4 supplied to and discharged from the respiratory tract 5, wherein the ventilation process occurs within pressure range 9 and volume range 10. Figure 7 It shows according to Figure 3 The square of the velocity of the ventilation process is 32, i.e., (s(t)) 2 . Figure 8 It shows that according to Figure 4 The square of the velocity of the ventilation process is 32, i.e., (s(t)) 2 By using control device 6, the ventilation process can be set in such a way that the square of the velocity distribution (s(t)) of pressure P7 and volume V8 during fluid supply and discharge 4 is equal to the velocity distribution of fluid 4. 2 32 (i.e., (s(t)) 2 =(dP / dt) 2 +(dV / dt) 2 The mean square of the velocity of the ventilation process (sD243) varies by at most 300% for at least 80% of the ventilation process duration. Clearly, in Figure 7 There exists a single maximum value in it, while Figure 8 In this context, the square of the velocity 32 has a more uniform distribution. Units are not specified here. However, it has been found that in the ventilation technique described herein, a significantly reduced power loss 28 and therefore a significantly lower energy loss 29 can be achieved during the ventilation process (time 44). The power loss PW(t) 28 corresponds to the square of the velocity (s(t)). 2 The distribution of 32.

[0237] List of reference numerals

[0238] 1. Ventilation device

[0239] 2. Fluid supply unit

[0240] 3. Fluid Discharge Unit

[0241] 4. Fluid

[0242] 5. Respiratory tract

[0243] 6. Control device

[0244] 7 pressure P

[0245] 8 volume V

[0246] 9 pressure interval

[0247] 10 volume interval

[0248] 11 pressure P0

[0249] 12 first volume

[0250] 13 second volume

[0251] 14 volume V0

[0252] 15 first pressure

[0253] 16 second pressure

[0254] 17 visualization device

[0255] 18 first curve section

[0256] 19 second curve section

[0257] 20 area

[0258] 21 critical area

[0259] 22 intervention limit

[0260] 23 first slope

[0261] 24 second slope

[0262] 25 compliance C

[0263] 26 volume flow rate F(t)

[0264] 27 airway resistance

[0265] 28 power loss PW(t)

[0266] 29 energy loss E

[0267] 30 critical power loss

[0268] 31 critical energy loss

[0269] 32 square of the velocity (s(t)) 2

[0270] 33 critical square of the velocity

[0271] 34 variable

[0272] 35 compliance curve

[0273] 36 pressure P1

[0274] 37 pressure P2

[0275] 38 tidal volume V T

[0276] 39 pressure sensor

[0277] 40 catheter

[0278] 41 cross section

[0279] 42 mean volume flow rate

[0280] 43 mean square of velocity

[0281] 44 time t

Claims

1. A ventilation device (1) for ventilating a patient, comprising at least a fluid supply unit (2) and a fluid discharge unit (3), which are adapted to supply fluid (4) into at least one airway (5) of the patient and to discharge fluid (4) from the airway (5), respectively; and a control device (6), which is configured to set a distribution of a pressure P (7) in the airway (5) and a distribution of a volume V (8) of fluid (4) supplied to and discharged from the airway (5) during ventilation of the at least one airway (5), i.e. at least once during a ventilation process of the at least one airway (5) by operating the ventilation device (1), in accordance with V = f ZP (P) and V = f AP (P) or in accordance with P = f ZV (V) and P = f AV (V), wherein, V = f ZP (P) and P = f ZV (V) represents the distribution of the volume V (8) and the pressure P (7) supplied when fluid (4) is supplied into the at least one respiratory tract (5), V = f AP (P) and P = f AV (V) represents the distribution of the volume V (8) and the pressure P (7) discharged when fluid (4) is discharged from the at least one respiratory tract (5), wherein the ventilation process takes place within a pressure interval (9) and a volume interval (10); wherein the ventilation process can be set by the control device (6) in such a way that the volume flow rate F(t) (26) during the supply of fluid (4) and during the discharge of fluid (4) varies by at most 50% relative to the average volume flow rate FD (42) in the ventilation process over at least 80% of the duration of the ventilation process.

2. Ventilation device (1) according to claim 1, wherein V = f ZP (P) or P = f ZV (V) is a first curve section (18), V = f AP (P) or P = f AV (V) is a second curve section (19), wherein the discharge of fluid from the at least one airway (5) is controlled and monitored by the control device (6) according to the profile of the first curve section (18); wherein the control device (6) is adapted to determine an area (20) enclosed by the first curve section (18) and the second curve section (19) of one ventilation process in a volume-pressure diagram; wherein at least one of the following parameters can be displayed in a visually discernible manner via a visualization device (17): a parameter a: a measure of the size of the area (20); or a parameter b: a measure of the change in the area (20) over a plurality of ventilation processes; or a parameter c: a measure of the ratio of the area (20) to a critical area (21) established for a given patient; or a parameter d: a measure of the change in the ratio of the area (20) to a critical area established for a given patient over a plurality of ventilation processes.

3. The ventilation device (1) according to claim 2, wherein At least one of the parameters a to d can be displayed in association with at least one intervention limit (22).

4. The ventilation device (1) according to claim 1, wherein, assuming the airway resistance R (27) of the patient's airway (5), the control device (6) is adapted to operate according to PW(t) = R1*(F(t)). 3 +R2*(F(t)) 2 To determine the power loss PW(t) of the airway (28), where the value of R1 is R, and the unit is pascal / (m²). 3 / s) 2 And the value of R² is R, with units of pascal / (m²). 3 / s); wherein at least one of the following parameters can be displayed in a visually recognizable manner via a visualization device (17): a power loss PW(t) (28); or an energy loss E (29) over a period of time, that is, the integral of PW(t)dt, that is, ∫PW(t)dt; or a measure of the ratio of the power loss PW(t) (28) to a critical power loss (30) determined for a given patient; or a measure of the ratio of the energy loss E (29) to a critical energy loss (31) established for a given patient.

5. The ventilation device (1) according to claim 1, wherein by using the control device (6) the ventilation process can be set in such a way that the square of the velocity of the distribution of the pressure P (7) and the volume V (8) during the supply of fluid (4) and the discharge of fluid (4) (s(t)) 2 (32) i.e. (s(t)) 2 = (dP / dt) 2 + (dV / dt) 2 varies by at most 300% relative to the average velocity square sD 2 (43) over the duration of the ventilation process.

6. The ventilation device (1) according to claim 1, wherein the control device (6) is adapted to determine the square of the velocity of the distribution of the pressure P (7) and the distribution of the volume V (8) when supplying and discharging the fluid (4) (s(t)) 2 (32), i.e. (s(t)) 2 = (dP / dt) 2 + (dV / dt) 2 wherein at least one of the following parameters is visually discernibly displayed via a visualizing device (17): the square of the speed s(t), i.e. (s(t)) 2 or over time (s(t)) 2 the integral of dt, i.e. ∫(s(t)) 2 dt; or the square of the velocity (s(t)) 2 (32) a measure of the ratio of the square of the velocity (s(t)) to the square of the critical velocity (33) established for the given patient; or (s(t)) 2 a measure of the ratio of the integral of dt to the critical value of the variable (34) established for the given patient.

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