DE2647378A1 - CONTROLLING A DIRECT ACTING VENTILATION DEVICE - Google Patents

Description

F. HoiFmann-La Roche & Co. Aktiengesellschaft, Basel / Switzerland

Control of a direct acting projection device

The present invention relates to a volumetrisch.es Device for assisted and controlled ventilation of patients.

They are devices for carrying out so-called ventilation treatments for assisted and / or controlled ventilation known from patients whose physiological respiratory activity is insufficient or insufficient j, st. These ventilators are general known and used in the fields of surgery and anesthesia as well as in nursing in general Used by patients, injured persons and others in whom natural breathing is inadequate.

The devices of known type can be divided into two main categories. One category includes the devices for which Am a rhythmic pumping system. Lung system of the patient • is assigned and comprises a volume-variable chamber (practically

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table an alternating pump), through which air or another gas mixture (for example a mixture of oxygen and nitrogen, to which anesthetic agents or others have been added) are sucked in and blown into the patient's lungs. Such devices are "direct acting" devices. The other category includes devices wherein the blowing through a so-called "compressible gas precursor", for example air, which is rhythmically ejected through a pumping station and into a non-expandable Ka m mer or inserted a container whose interior by a wall (in general, the ¥ and an expandable and contractible ball or bladder), which is deformable by the gas rhythmically introduced by the pumping mechanism, and which is connected to the patient's lungs with the help of suitable one-way valves. An example of devices of the first category is described and illustrated in U.S. Patent 3,818,806, while an example of devices of the second category is described and illustrated in U.S. Patent 3,658,443.

Whichever category these devices belong to, from which also a detailed technical and patent law Literature exists, one has always tried to describe the conditions of the mechanical or "compulsory" blowing of the physiology of the Adapt breathing in the best way depending on the pathological conditions of the individual patient. In addition to the systems for adjusting the frequency of the breathing rhythm (generally expressed in terms of the number of breaths per minute), the with suitable means by changing the speed and / or the cycle time of the actuating the pumping station Drive means is made, various means are known to be provided in advance of the various parameters of the assisted and controlled ventilation, e.g. the volume ratio of the gas mixture blown in (generally with liters per minute at room pressure), to determine the increase and / or the maximum value of the mixture blown, etc.

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To this end, various mechanisms have been proposed for the selective predetermination of these and other parameters and applied comprising various mechanical or pneumatic means. In each case, the expediency depends the choice between the values permitted on the basis of the settings field of the devices always depends on the intervention and the responsibility of the clinician operating the device, to whom the The task is to act on the adjustment means every time there is a sensitive incompatibility between the activity of the Device and the current physiological conditions of the patient, i.e. the so-called "compliance" (or the condition of receptivity) on the part of the patient; the latter depends on the elasticity of his chest / lungs, of his system the initial and total resistances, i.e. the elastic and / or frictional resistances in the laringo-broncho-pulmonary system of the patient etc.

The elastic, mechanical or pneumatic ones connected between the pumping station and the patient's lung system Means must not have any other puncture than that, at times the balance disturbance between the applied force and acceleration and to compensate for the resistance that appears during the inhalation process, i.e. the injection into the breathing rhythm.

It is also known that these attitudes and predictions require the presence and use of very complicated mechanisms in order to have independent adjustability of the various parameters to allow. One example is the complexity of the adjustable drive means of the pumping station for artificial respirators is reproduced in U.S. Patent 3,651,804.

The object of the present invention is to create a volumetric device for supported and controlled

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lated ventilation of patients, with the use of complicated mechanisms to establish and adjust the various Respiratory parameter is not required.

According to the invention, this object is achieved by a volumetric device for assisted and controlled ventilation solved by patients, the a volume-variable chamber comprehensive pumping mechanism, means for one-way connection of the Inside this chamber with the patient's pulmonary system and a motor connected to the variable volume chamber for actuating the pumping station, characterized in that this motor is an electric motor, its torque and Circulation speed can be changed selectively and is fed via a circuit comprising programmable means, in order to supply the motor with electrical energy programmed as a function of the time and consequently to the previously in the gas mixture sucked into this chamber and blown into the patient's lung system has a correspondingly changed pressure Apply the inhalation process of the respiratory cycle.

In the device according to the invention, namely, directly and electronically and therefore without complicated mechanisms, the origin of the driving force used in the pumping station is affected, so that the thrust applied to the moving means of the pumping station, is applied in particular to components that are set in alternating motion, is dosed progressively and selectively, so that the extent and / or the progression of the blowing in depends on the conditions of the instantaneous equilibrium between the force applied and the resistance encountered at each moment, with such a spontaneous, constant adjustment the movement, as far as the acceleration and the momentary force are concerned, to the real and also changeable conditions of receptivity is achieved on the part of the patient.

Preferably this electric motor is with variable 709817/0803

Torque comprises a DC motor and said circuit preferably adjustable means for selective predetermination the time and means corresponding to the total time of a breath to operate on this motor for a predetermined fraction this time electrical drive energy to apply progressively increasing value and such a sign that in this Eammer causes a negative volumetric change up to a minimum volume; whereby .between these means for the application of electrical energy and the engine power amplification means with a range between zero and infinity Output impedance are switched.

In this way, the characteristics of the direct current motor (speed strictly dependent on the supply voltage and torque strictly dependent on the end of the engine durchf hess Current intensity) can be used appropriately and agreed with those who derive from the output impedance value of the amplification means so that in the pumping station a progressively increasing evacuation thrust and, at the same time, an evacuation speed is ensured, which, as desired, depends on the resistance that the patient opposes the evacuation himself.

These and other features of the present invention will become apparent from the following detailed description of an embodiment which is shown for example in the attached drawings: '

In the drawings show:

Figure i schematically a volumetric according to the invention Device with the corresponding control and regulation circuit;

FIG. 2 shows some waveforms of signals illustrating the operation of the device of FIG.

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The ventilator shown in Figure 1 comprises a pumping station 1, the main component of which consists of a deformable Bellows 2 is in connection with a first, fixed end wall 3 and a second, movable end wall 4 in its interior a variable volume chamber 5 defined, which is controlled by a check valve 7 with a Air supply line 6 and an exhaust or injection line 8 controlled by a check valve 9 is provided. The line 8 is also provided with a safety valve 10 for discharging any excess pressures and is connected to the Hose 11 connected to be introduced into the patient's trachea is. An exhalation or outlet line 12 is also connected to the hose 11 and extends in the direction of a Outlet 13 with the aid of a controlled by a solenoid 15 Valve 14 can be opened.

The movable end wall 4 of the bellows 2 is attached to a plate 16 which is used for alternate emptying and Püllhübe the chamber 5 is alternately moved back and forth by a direct current motor 17 to which a screw 18 is continuously coupled in a pipe 19 with an internal thread, which transforms the alternating rotating movement of the shaft 20 of the motor 17 allowed in an alternating rectilinear movement.

The direction of rotation of the motor 17 is determined by the polarity of the Its terminals 21 and 22 are supplied with power, the terminal being grounded via a resistor 23. The supply polarity depends on the state of two switches 30 and 31 (with corresponding Resistors 32 and 33 in series connection), each between the line 29 and the circuit node 34, where there is a positive ramp voltage with periodic repetition, and between same line 29 and an end clamp 35> where a continuous negative voltage is present, are switched.

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In addition, two feedback loops are provided, each comprising diodes 25 and 26 (with respective resistors 27 and 28) which define the output impedance of amplifier 24. «Each circle acts for a certain supply polarity of the motor 17.

The ramp voltage present at the circuit node 34 is generated by an integrator 36 with a corresponding capacitor 37 and has a variable inclination which depends in a predetermined manner on the presetting of a potentiometer 38. These Ramp voltage is periodic by a circle with reference threshold 39, which when a certain reference value is reached Ramp a switch 40 connected in parallel with the capacitor 37 closes and so with the discharge of the latter the momentary one closes Cancellation of the voltage at node 34 causes.

For actuation in the open and closed position of the movement reversal switch 30 and 31, a control unit 41 is provided, which is able to assume three different functional divisions » namely those with the switch 30 closed and the switch open 31 (advance "of the movable plate 16 to empty the chamber 5 and for blowing air into the patient's lungs), those with open switch 30 and closed switch 31 (retraction the plate 16 for sucking air into the chamber 5) and those with open switches 30 and 31 (plate 16 stationary).

The first position is when the threshold circuit 39 reaches the mentioned reference value on the part of the ramp voltage in node 34 not only closes switch 40 and brings integrator 36 into zero position, but also the control unit 41 specifies a signal 42 for the start of the shift. the The second position is when one of a port set

44 of the plate 16 reached limit switch 43 an end-of-travel detector

45 allows the control unit 41 to be given an end-of-travel signal. Finally, the third position is when a counter 47

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feels that the detected by means of a magnetic detector 48 coupled to a ring gear 49 of the shaft of the motor 17 The speed of the motor 17 has reached a predetermined value which can be set by a potentiometer 50 and so on its output 51 a final retraction signal for the control unit 41 gives up. On the other hand, the same condition can exist if another one reached by the extension 44 of the plate 16 Limit switch 52 controls a detector 53, so that it has a signal at its output 54 to limit the greatest retraction for the control unit 41 delivers.

The device shown in FIG. 1 finally includes a comparator 55 'which the ramp voltage present at node 34 with a given, variable reference value (the

in any case smaller than that which was determined for the threshold circuit 39, and larger than that which the ramp voltage can reach itself before the extension 44 hits the limit switch 43) compares that of the potentiometer 56 is delivered. If the two input values coincide, the comparator 55 acts on a control unit 57, so that this is done to control the momentary excitation of the solenoid 15 to open the exhalation valve 14.

The mode of operation of the device shown in Figure 1 is illustrated with the aid of the timing diagrams a, b, c, d, e, f of Figure 2 shown waveforms clearly. The duration T of each breath and its repetition rhythm or frequency are determined in combination by the integrator 36 and the threshold circuit 39, the first having a ramp voltage from the Presetting of the potentiometer 38 produces a dependent, variable inclination and the second generates this voltage (by means of the switch 40) is canceled and the cycle is triggered again as soon as this ramp voltage has reached the end of a period that depends on its slope threshold VS determined by circle 39 (FIG. 2a) achieved.

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It is taken into account that the control unit 41 is initially in the + state, which means that the switch is closed 30 and the opening of the switch 31 provides, the in the node 34 generated ramp voltage initially to the motor 17 via the amplifier 24 (Fig. 2b), strictly speaking to the terminal 21 via the. Diode 25 applied so that the motor 17 is thus brought into circulation is that the plate 16 is advanced for emptying the chamber 5 with a thrust increasing with the ramp voltage becomes (to the right in Figure 1). If an output impedance expediently selected between zero and infinity is ensured in amplifier 24, the rate of emptying is also increasing (FIG. 2c), which however is able to reduce that on the part of the patient to take into account the opposite resistance to emptying. The real G-speed during this emptying process becomes influenced by the resistance opposite from the patient depending on the given value of the impedance. The one in the Chamber 5 contained air is so through the one-way valve 9 in the lungs of the patient in the so-called dynamic part D of Inhalation process I of the breath is blown in (Fig.2f, which shows the pressure curve at the tracheal level inside the patient).

O ·

The advancement of the plate 16 is terminated as soon as its extension 44 reaches the limit switch 43 and is actuated; at this Position, the end-of-travel detector 45 emits a signal at output 46, which leads the control unit 41 to cause the switch 30 to open and the switch 31 to close. Using the Amplifier 24, a constant, negative voltage (Fig. 2b) is available at the end terminal 35, which is no longer available at terminal 21, but at the terminal 22 of the motor 17 (now the diode 26 is conductive), whereby this is controlled to the reverse • to run around at a constant speed and thereby cause a corresponding retraction of the plate 16 (Fig. 2c).

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The chamber 5 can be filled with air via the line 6 opened by the valve 7, while the Y-valve 9 the Line 8 closes appropriately.

The inhalation process I is, however, continued with the so-called static part S. This latter will end as soon as before the end of the return stroke of the plate 16, the ramp voltage generated in the node 34 reaches the predetermined value VE (Fig. 2a), which leads the comparator 55 to control the opening of the exhalation valve 14 via the control unit 57 and the solenoid 15. The air previously blown into the patient's lungs can be exhaled in this way (exhalation process E). the Closing and opening times of valve 14 and the theoretical and the actual processes of the resulting pressure in the patient can be clearly seen in Figures 2d, e, f. In FIGS. 2b, c, e, f it is indicated by dotted lines how the curves with the opposed resistance by the patient if the The set parameters of the device have been changed.

The withdrawal stroke of the plate 16 and therefore the filling of the Chamber 5, however, are ended as soon as the counter 47 is addressed by means of the magnetic detector 48 that the speed of the motor 17 has reached the value specified by the potentiometer 50. At this point, a signal 54 is sent to the control unit 41 to switch to the state that allows you to control both switches 30 and 31 in the open position. Not that more fed (Fig. 2b) motor 17 and with it the plate 16 (Fig. 2c) are stopped. Should be for some reason (Including incorrect entry of the power frequency parameters required by the device) if this is achieved the specified speed does not occur, the plate 16 would be forced to the highest possible position by the limit switch 52 set retreat stopped because of the impact of the extension 44 on the limit switch-52 emitting a signal 54 that is able to act on the control unit

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41 acting in essentially the same way as that
mentioned signal 51

The breath is finally stopped as soon as the im
Enoten 34 generated rainpen tension reached the threshold value VS established by district 39. At this point, besides the already mentioned generation of the cancellation of the integrator 36 by means of the switch 40, the circuit 39 generates a signal 42 which returns the control unit to the initial state, ie with the switch 30 in the closed position and the switch 31 in the open position.

The cycle described is now repeated in order to carry out a further breathing cycle of the same duration. The duration and the frequency of the breathing cycles can, as already mentioned, be set via the potentiometer 38, as can the ratio of the duration E / l between the exhalation process and the inhalation process via the Potentiometer 56 and the air blown in with each pumping process can be adjusted via potentiometer 50. From these attitudes The course of the curve shown in FIG. 2 depends on the figure Waveforms.

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Claims (1)

Claims Volumetric.es device for assisted and controlled Ventilation of patients, a pumping mechanism comprising a chamber that can be changed in volume, means for a one-way connection the interior of this chamber connected to the patient's pulmonary system and one connected to the variable volume chamber Motor for actuating the pumping station, characterized in that this motor is an electric motor with selectively variable Torque and rotational speed is and fed through a programmable means comprehensive circuit is to supply the motor with electrical energy programmed as a function of the time and consequently to the Gas mixture previously sucked into this chamber and blown into the patient's lung system changed a correspondingly Apply pressure during the inhalation process of the respiratory cycle. 2. Apparatus according to claim 1, characterized in that the electric motor is a direct current motor and the circuit is adjustable means for selectively predicting one of the Total time of a breath includes corresponding time and means to power on this motor for a predetermined fraction of time Drive energy to be used with progressively increasing value and a sign such that in this chamber a negative Volume change is caused up to a minimum volume, with power amplification means between these means and the engine are switched with an output impedance value between zero and infinity. ORIGINAL INSPECTED 709817/0803 '3. Device according to Claim 2, characterized in that this circuit has means for reversing this electrical energy at the end of the negative change in volume of the chamber or the predetermined fraction of time, if this change in volume is not is ended within this fraction of time, includes a positive change in this internal volume in preparation for the following To achieve inhalation process. 4. Device according to one of claims 2 and 3, characterized by means for measuring the deflection of the variable volume Chamber granted movement in the event of a positive change in volume and to stop the movement even when it is reached a range of motion with a specified value. 5. Apparatus according to claim 1, characterized in that that the variable volume chamber comprises at least one movable wall that the motor makes an alternating movement with each Breath granted. 6. Apparatus according to claim 5, characterized in that the electric motor in the manner of a rotary motor and with the movable Wall by means of a mechanism for converting a rotary movement into a linear, alternating movement mechanically connected is. 7. Apparatus according to claim 5, characterized in that the variable volume chamber has a fixed end wall, a movable end wall and a bellows-like deformable side wall comprising the two aforementioned walls along their circumference connects. 8. Apparatus according to claim 6, characterized in that the mechanical connection between the motor and the movable wall is a screw and nut system. 709817/0803