DE102004052755B3 - Selective removal of carbon dioxide from inhalation or respiratory gas mixtures, comprises using a temporary storage device together with carbon dioxide filters - Google Patents

Abstract

Selective removal of carbon dioxide from inhalation gases or CO2-containing respiratory gas mixtures by: (a) passing exhaled gas through a temporary storage device (9); (b) passing the drawn-off gas of low anesthetic content through a filter (11); (c) returning the mixture to (9) to enrich it with anesthesis gas; and (d) returning the gas of low CO2 content to the patient. Selective removal of carbon dioxide from inhalation gases or CO2-containing respiratory gas mixtures involves (a) passing exhaled gas from the patient through a temporary storage device (9); (b) passing the drawn-off gas of low anesthetic content through a filter (11) to draw-off CO2; (c) returning the mixture to device (9) to enrich it with anesthesis gas; and (d) returning the gas of low CO2 content to the patient. An independent claim is also included for apparatus for the removal including: (i) a tube (6) for collecting exhaled gas connected to Y-piece (4); (ii) a system (3) connected to a one-way valve (2,7) and a conduit (13,14) for circulating the gas; (iii) an anesthesis gas temporary storage device (9) adsorbing the anesthetic and allowing the gas mixture to flow to-and-fro; and (iv) a CO2 filter (11) downstream from device (9).

Description

The The present invention relates to a method for selective removal of carbon dioxide from inhalation narcotics and carbon dioxide-containing breathing gas mixtures and an apparatus for carrying out this method. The selective removal of carbon dioxide from inhalation anesthetics and Carbon dioxide-containing breathing gas mixtures is in rebreathing systems necessary at anesthesia used by patients. In such Rückatemsystemen that of the Patients exhaled gas after removal of exhaled carbon dioxide returned to the patient. These Systems have opposite Systems where constantly fresh gas is supplied to the patient, the advantage that the respiratory conditioning by the supply of exhaled gas, which is heated by the patient and is moistened, improved and the volatile used anesthetics can be used more effectively.

In market Rebreathing systems becomes almost exclusively today the removal of the carbon dioxide with hydroxide mixtures of the alkali metal and alkaline earth metals. This is the carbon dioxide with. the hydroxide to form Carbonate and water reacted, releasing thermal energy becomes. The respective hydroxide can be used only once, since a reprocessing with a reasonable effort not can be realized. The method for absorbing carbon dioxide using Hydroxide (soda lime) has a number of disadvantages, such as a lot of effort to control and change the lime filling in anesthesia machine (the typical service life is 5 hours), the possibility of Drying out of the lime and, consequently, the danger of lime in the presence of anesthetic gases harmful substances are formed, and the water, which in the absorption of carbon dioxide by Hydroxide is formed, which influences the absorption process. The generated Thermal energy can be the volatile anesthetics used change.

To solve this problem proposes the DE 197 29 739 A1 a method in which the hydroxide mixtures of alkali and alkaline earth metals (soda lime) are replaced by molecular filter materials. This publication describes in 1 a method for the removal of carbon dioxide from inhalation anesthetics and carbon dioxide-containing breathing gas mixtures in which exhaled gas mixture is passed through a moisture exchanger, where the gas mixture moisture is removed, the low-moisture gas mixture is passed through molecular sieve, where the gas mixture carbon dioxide is removed, and the moisture and Low-carbon gas mixture via the moisture exchanger to the patient is returned.

But that too in the DE 197 29 739 A1 described method has several disadvantages and is not applied in practice. Preconditioning of the molecular sieve with anesthetic gases such as isoflurane, enflurane, sevoflurane, desflurane, halothane, etc. requires uneconomically high amounts of these gases. The resulting expense of refilling the anesthetic gases is high and leads to negative environmental effects in the subsequent gas release. The requisite preconditioning with anesthetic gases also means that the anesthesiologist is limited in the choice of anesthetic gas concentration, since the molecular sieve is locally in an equilibrium state and when changing the concentration of anesthetic gas time delays in the change in concentration, the patient experiences. The required balance must first be restored. The preconditioning with anesthetic gases is technically complex, since, inter alia, an additional gas dosage is needed.

at anesthesia units it is also desirable that many features possible Patients are stored remote, so that the surgeon is not obstructed by the devices becomes.

task The present invention is an improved method for selective removal of carbon dioxide from inhalation anesthetics and provide carbon dioxide-containing breathing gas mixtures, in which the aforementioned disadvantages do not occur. Task of It is also an object of the present invention to provide a device with the inventive method carried out can be.

to solution the object is a method with the features of claim 1 and a device with the features according to claim 7. Advantageous embodiments emerge from the subsequent subclaims.

The invention will now be described with reference to the attached figures, wherein 1 is a schematic representation of the device according to the invention,

2 and 3 are schematic representations of a preferred anesthetic gas buffer and are

4 a schematic representation of a regeneration system according to the invention for the carbon dioxide filter.

In the following, the invention will be described first with reference to FIG 1 described.

In the method according to the invention, the breathable gas mixture exhaled by the patient and containing carbon dioxide and inhalation anesthetics is passed through a Y-piece 4 led into a respiratory gas circulation, its way through check valves 2 . 7 is controlled. In the breathing gas circulation, the respiratory gas mixture is first passed through an anesthetic gas buffer 9 where inhaled anesthetics are withdrawn from the gas mixture: The inhalation anesthetic gas mixture is then passed through a carbon dioxide filter 11 passed, where the gas mixture carbon dioxide is removed. That from the carbon dioxide filter 11 Exiting, inhalation anesthetics and low carbon dioxide gas mixture is through the anesthetic gas buffer 9 returned, where the gas mixture is enriched with inhalation anesthetics again. Finally, the low-carbon gas mixture through the Y-piece 4 returned to the patient for inhalation.

Preferably, an activated carbon filter is used as an anesthetic gas buffer 9 used. Further, it is preferable to use a molecular sieve as a carbon dioxide filter 11 to use.

According to another embodiment, expired gas mixture is passed through a moisture exchanger 5 where the gas mixture is deprived of moisture before passing through the Y-piece 4 directed into the respiratory air circuit and the anesthetic gas buffer 9 is supplied. To reduce the dead volume, which may be necessary especially in patients with low lung volume, the moisture exchanger 5 but also omitted. The respiratory gas moisture in this case from the anesthetic gas buffer 9 reversibly absorbed before the gas enters the carbon dioxide filter 11 enters, and released again into the low-carbon gas mixture after it leaves the carbon dioxide filter 11 has leaked.

If necessary, additional gas optionally containing inhalation anesthetics may be introduced through a fresh gas inlet 12 be supplied. Excess anesthetic gas may optionally by a gas transfer 1 . 10 be dissipated. It is also possible, the breathing gas mixture within the gas line system 3 or the housing of the anesthetic gas buffer 9 enriched with medicinally active substances such as volatile anesthetics.

The device according to the invention includes accordingly

• i. a tube 6 , which is suitable for receiving and delivering breathing gas of a patient and on the side facing away from the patient with a
• ii. Y-piece 4 is connected, which branches the breathing gas flow and that with a
• iii. Gas line system 3 , comprising check valves 2 . 7 and at least one gas conveying element 13 . 14 , is connected, in which the breathing gas mixture can be circulated,
• iv. an anesthetic gas buffer 9 , which is suitable for the adsorption of inhalation narcotics and through which the breathing gas mixture is fed back and forth and
• v. at least one anesthetic gas buffer 9 downstream carbon dioxide filter 11 which can extract carbon dioxide from the breathing gas mixture, with both the inlet and the outlet of the carbon dioxide filter (s) 11 with the anesthetic gas buffer 9 is connected / are.

According to a preferred embodiment, the anesthetic gas buffer is 9 an activated carbon filter. According to a further preferred embodiment, the carbon dioxide filter contains 11 a molecular sieve. Optionally, a moisture filter 5 the Y-piece 4 upstream, which can withdraw moisture reversibly from the expired gas mixture. A separate anesthetic gas dosage can also be sent to the gas line system 3 be connected.

Advantageously, in the gas line system 3 a resuscitation bag 8th integrated, which serves as a reservoir and particularly preferably the anesthetic gas buffer 9 and carbon dioxide filters 11 upstream.

In accordance with a further preferred embodiment, at least one gas outlet valve is furthermore provided 1 . 10 into the gas pipeline system 3 integrated into anesthetic gas transfer. Particularly preferred is the gas outlet valve 10 the anesthetic gas cache 9 after- and the carbon dioxide filter 11 upstream.

According to a further preferred embodiment, this is at least one gas conveying element 13 . 14 a radial compressor. The at least one gas delivery element 13 . 14 can be anywhere on the breathing gas circuit. Preferably, the min is at least one gas conveying element 13 . 14 the check valve 7 immediately downstream and / or the check valve 2 immediately upstream.

According to a further preferred embodiment, a fresh gas inlet 12 into the gas pipeline system 3 integrated. Preferably, the fresh gas inlet 12 the carbon dioxide filter 11 and the anesthetic gas cache 9 downstream.

Anesthetic gas plenum

Filters for the removal of inhalation anesthetics are known from the prior art. Activated carbon containing filters are described, for example, in U.S. Patent 5,471,979. A particularly preferred active carbon-containing anesthetic gas buffer is described in U.S. Pat EP 1 440 704 A1 described. However, the known activated carbon filter are usually close to the patient on the tube 6 attached, whereby additional dead volume is generated. According to the invention the Anarkosegaszwichenspeicher 9 Patients fern arranged in the anesthesia machine and directly to the carbon dioxide filter 11 upstream and downstream.

The from the EP 1 440 704 A1 known anesthetic gas buffer has a housing with at least two externally accessible gas channels and a movably arranged between the gas channels, disc-shaped filter to continuously arrange a portion of the filter within a respective gas channel. Such an anesthetic gas buffer, as in 1 of the EP 1 440 704 A1 is described, is particularly preferred according to the invention.

According to a further embodiment, the anesthetic gas buffer contains 9 disc-shaped activated carbon filter 30 for the rotational movement. between the gas channels 40 . 50 angeord net are (see 2 ). Preferably, the gas channels 40 . 50 arranged in parallel.

Most preferably, the anesthetic gas buffer comprises other means 60 . 70 (see. 3 ), with which sections 32 . 34 of the filter 30 that are not inside a gas channel 40 . 50 are arranged, can be treated. The treatment includes, for example, sterilizing the sections 32 . 34 passing through one or more partitions 21 are separated. In 3 is in the section 31 the content of inhalation anesthetics in the gas stream 40 reduced. The inhalation narcotic-poor gas stream is fed to the carbon dioxide filter (not shown). In the section 33 becomes the gas stream leaving the carbon dioxide filter 50 again enriched with inhalation narcotics. In the sections 32 and 34 the filter is neither the gas flow 40 still the gas flow 50 exposed and can be subjected to different conditioning steps. The conditioning can on the one hand change the degree of loading of the sorbent (eg by application of a purge gas stream 60 or a temperature change), on the other hand, the sorbent can be sterilized (eg by application of UV or higher-frequency radiation 70 or germicidal gases or liquids).

Alternatively or additionally, a bacteria filter can be integrated into the circulation. The sections 32 and 34 can be additionally subdivided. The housing of the anesthetic gas buffer 9 can also get more funds 60 . 70 include sections, such as sections 32 . 34 , the filter 30 that are not inside the gas channel 40 . 50 are arranged to be enriched with medicinal substances such as volatile anesthetics.

The rotational speed of the filter 30 should be selected depending on the amount of breathing gas and the capacity of the filter as well as the loading of the gas flow. According to the invention, instead of uniform or intermittent rotation, an operation with a "skipping" rotational movement can be selected. In this case, for example, in an arrangement 3 the section 32 abruptly 180 ° to the location of the section 34 and the section 31 abruptly 180 ° to the location of the section 33 turned. The filter is divided into essentially two zones that are subject to different functions. For example, while the section pair 31 and 33 in a first zone continuously the concentration of inhalation nakotika of gas flow 40 minimizes and gas flow 50 again enriched with anesthetic gas, the section pair becomes 32 and 34 In a second zone thoroughly regenerated, sterilized or otherwise preconditioned. In an arrangement according to 3 then performs a rotation through 90 ° to the cyclic permutation of the pairs of sections. The number of sections can be increased, for example, with even-numbered section numbers being preferred. Accordingly, of course, the rotation angle must be reduced.

arrangement the carbon dioxide filter

Particularly preferred (see 4 ) are two carbon dioxide filters 130 . 131 connected in parallel, so each one carbon dioxide filter 131 can be regenerated while the other 130 is in operation. The carbon dioxide filter must therefore no longer be removed from the rebreathing system for reprocessing and the device can also be operated continuously for longer periods of time. The regeneration of the carbon dioxide filter 131 is performed in the counterflow direction to the flow direction during the operation, so that the influence range of the water vapor adsorption is limited to a small particle area of the sorbent.

In 4 becomes inhalation narcotic-free breathing gas from the rebreathing system 126 via a valve 128 to the carbon dioxide filter 130 directed, where the breathing gas mixture carbon dioxide is withdrawn, and valve 132 in the rebreathing system 127 back directed. valves 128 and 132 are in 4 in operating position and can via control 135 be switched in regeneration position. At the same time, the parallel carbon dioxide filter 131 regenerated in the counterflow direction. For this purpose, regeneration gas mixture from a reprocessing system 137 over valve 133 in carbon dioxide filters 131 where the regeneration gas mixture is enriched with carbon dioxide and via valve 129 into the reprocessing system 136 returned. valves 133 and 129 are in regeneration position and can be controlled by 135 be switched to operating position.

The Contains filter material preferably molecular sieve, but may also contain conventional soda lime. As usual available Molecular sieves are very hygroscopic and by the presence of Residual moisture in the carbon dioxide absorption capacity can be significantly reduced is with the inventive arrangement a more effective regeneration possible.

Claims (22)

Process for the selective removal of carbon dioxide from inhalation anesthetics and carbon dioxide-containing breathing gas mixtures, in which i. gas mixture exhaled by the patient through an anesthetic gas buffer ( 9 ), where inhalation anesthetics are withdrawn from the gas mixture, ii. the inhalation anesthetic gas mixture by carbon dioxide filter ( 11 ) is passed, where the gas mixture carbon dioxide is removed; iii. the inhalation anesthetic and low carbon dioxide gas mixture through the anesthetic gas buffer ( 9 ), where the gas mixture is enriched with inhalation anesthetics, iv. the low-carbon gas mixture is returned to the patient. A method according to claim 1, characterized in that an activated carbon filter as anesthetic gas buffer ( 9 ) is used. A method according to claim 1 or 2, characterized in that a molecular sieve as carbon dioxide filter ( 11 ) is used. Method according to one of the preceding claims, characterized in that the exhaled gas mixture through a moisture exchanger ( 5 ), where moisture is removed from the gas mixture before it is added to the anesthetic gas buffer ( 9 ) is supplied. A method according to claim 4, characterized in that the low carbon dioxide gas mixture through the moisture exchanger ( 5 ), where it is re-enriched with moisture before being returned to the patient. A method according to claim 1 or 2, characterized in that in a further process step, the breathing gas mixture within the gas line system ( 3 ) or the housing of the anesthetic gas buffer ( 9 ) is enriched with medicinal substances. Apparatus for the selective removal of carbon dioxide from inhalant narcotics and carbon dioxide-containing respiratory gas mixtures, comprising: i. a tube ( 6 ), which is suitable for receiving and delivering breathing gas of a patient and on the side facing away from the patient with a ii. Y-piece ( 4 ) which branches the respiratory gas and which is connected to a iii. Gas piping system ( 3 ), comprising check valves ( 2 ; 7 ) and at least one gas conveying element ( 13 ; 14 ), in which the breathing gas mixture can be circulated, iv. an anesthetic gas buffer ( 9 ), which is suitable for the adsorption of inhalation anesthetics and through which the breathing gas mixture is fed back and forth and v. at least one of the anesthetic gas buffers ( 9 ) downstream carbon dioxide filter ( 11 ), which can extract carbon dioxide from the breathing gas mixture, wherein both the inlet and the outlet of the carbon dioxide filter or the carbon dioxide filter ( 11 ) with the anesthetic gas buffer ( 9 ) is / are connected. Apparatus according to claim 7, characterized in that to the gas line system ( 3 ) an anesthetic gas dosage is connected. Apparatus according to claim 7 or 8, characterized in that the anesthetic gas buffer ( 9 ) is an activated carbon filter. Device according to one of claims 7 to 9, characterized in that the carbon dioxide filter ( 11 ) Contains molecular sieve. Device according to one of claims 7 to 10, characterized in that a moisture filter ( 5 ) the Y-piece ( 4 ), which can reversibly withdraw moisture from the exhaled gas mixture. Device according to one of claims 7 to 9, characterized in that a resuscitator ( 8th ) into the gas pipeline system ( 3 ), preferably the anesthetic gas buffer ( 9 ) is connected upstream. Device according to one of claims 7 to 12, characterized in that at least one Gas outlet valve ( 1 . 10 ) into the gas pipeline system ( 3 ), preferably the anesthetic gas buffer ( 9 ) and the carbon dioxide filter ( 11 ) is connected upstream. Device according to one of claims 7 to 13, characterized in that the gas line system ( 3 ) via a fresh gas inlet ( 12 ), preferably the carbon dioxide filter ( 11 ) and anesthetic gas buffer ( 9 ) is connected downstream. Device according to one of claims 7 to 14, characterized in that the anesthetic gas buffer ( 9 ) a housing with at least two externally accessible gas channels ( 40 . 50 ) and one movable between the gas channels ( 40 . 50 ), disk-shaped filters ( 30 ) to a portion of the filter ( 30 ) continuously within a gas channel ( 40 . 50 ). Device according to claim 15, characterized in that the filter ( 30 ) is arranged for rotational movement between the gas channels. Apparatus according to claim 16, characterized in that the gas channels ( 40 . 50 ) are arranged in parallel. Device according to one of claims 15 to 17, characterized in that the housing further means ( 60 . 70 ), with which sections ( 32 . 34 ) of the filter ( 30 ) that are not within a gas channel ( 40 . 50 ) are arranged, can be sterilized. Device according to claim 18, characterized in that the further means ( 60 . 70 ) Include UV lamps. Device according to one of claims 7 to 19, characterized in that the housing of the anesthetic gas buffer ( 9 ) additional funds ( 60 . 70 ), with which sections of the filter ( 30 ) not within the gas channel ( 40 . 50 ) are arranged, can be enriched with medicinally active substances. Device according to one of claims 7 to 20, characterized in that two carbon dioxide filters ( 130 . 131 ) are connected in parallel, so that one can be regenerated while the other is in operation. Apparatus according to claim 21, characterized in that the regeneration of the carbon dioxide filter ( 131 ) is operated in the counterflow direction to the flow direction during operation.