WO2006046908A1

WO2006046908A1 - Improvement of a devcie for recovering anaesthetic and a method for recovering anaesthetic

Info

Publication number: WO2006046908A1
Application number: PCT/SE2005/001576
Authority: WO
Inventors: Hans Lambert
Original assignee: Hans Lambert
Priority date: 2004-10-25
Filing date: 2005-10-21
Publication date: 2006-05-04
Also published as: SE0402572D0

Abstract

The present invention relates to a device comprising a first unit which is an anaesthetic reflector used for absorbing anaesthetic medium from the gas exhaled by the patient and desorbs anaesthetic medium to the gas inhaled by the patient. According to the invention a second unit is arranged in the system, which distributes the anaesthetic in an even way in the gas inhaled by the patient. The supply of the anaesthetic is placed in between the first and the second unit. The device and the method according to the invention enable the gas inhaled to be correctly monitored by a gas monitor.

Description

Field of invention:

The present invention relates a device and method for recovering anaesthetic during the use of inhaled anesthetics.

Description of the background art:

Such devices and methods are disclosed through US patents 5044361, 6206002 and 6488028 for instance. The purpose of such devices are to reduce the consumption of anaesthetic preparations when treating a patient.

The US patent 5044361 describes an apparatus and a method where a so-called reflection filter is used in a housing. This reflection filter can be made of zeolite particles in between two filter materials, to avoid that particles are transported to the patient. The anesthetic gas is led into the housing containing the reflection filter in between the patient and the reflection filter with no special means to distribute the gas evenly in the gas stream. The concentration of the anaesthetic given to the patient is very important and in most cases it is necessary to monitor this concentration with a specially designed gas monitor. This is a drawback of the device and method described, as the gas (due to its high density) is not evenly distributed in the gas stream going to the patient and thus the gas sample monitored by the gas monitor will not be the average concentration of anaesthetic given to the patient but will vary from sample to sample due to uneven distribution of the gas in the gas stream.

The US patent 6206002 describes a device containing anaesthetic reflector and a second unit which has the ability to absorb and desorb water. This second unit is placed in between the - patient and the reflector. It also describes an anaesthetic supply apparatus connected in between the second unit and the patient. This arrangement gives the same problem to the device as in US 5044028 and the concentration of gas given to the patient is not evenly distributed in the gas stream and thus difficult to monitor correctly. The anaesthetic is mostly described as a gas, but if supplied in liquid form to the device, the problem would be even worse as no gas mixing or distributing arrangement is described.

The US patent 6488028 describes a device where a vaporizing device, called an evaporator, is placed in between the patient and a unit, called absorption-desorption filter, and where the gas passes across the vaporizing device. This evaporator is substantially impervious to the gases flowing to and from the patient and thus takes up a small portion of the cross-section of the housing surrounding it and the gases to and from the patient pass across it. It also describes a first unit described as an absorption filter and which can be laminated to a second unit described as a bacteria filter. The air stream going to the patient is passing through the first unit then the second unit and then across the evaporator before it goes to the patient. However, these devices have no means of distributing the anaesthetic in an even way in the gas stream and thus the gas monitor will monitor a varying concentration instead of a stable concentration.

Against this background, the object of the present invention is to alleviate this deficiency in the known devices and methods, and to increase the gas monitoring reliability and performance.

DISCUSSION OF THE PREFERRED EMBODIMENTS

In a particularly preferred embodiment of the invention the supply tube ends close to the surface of either the first unit or the second unit.

This has been found to have the surprising effect of greatly increasing the distribution of the anaesthetic into the gas going to and from the patient The optimal efficiency obtained with this preferred embodiment is probably a result of capillary transport of the anaesthetic in either unit one or two thus giving an even distribution of the anaesthetic.

In another preferred embodiment, preferably a variation of that described above, both the units, i.e. the anaesthetic reflector and the second unit, are located in a common housing. This simplifies the construction, making it more compact and easily managed. It also ensures that the two units are compatible from the point of view of size.

The supply means for the anaesthetic preparation is preferably arranged in the tube between the first unit and the second unit.

The above and other advantageous embodiments of the device according to the invention are defined in the sub-claims to the main method claim.

Equivalent advantageous embodiments of the method according to the invention are defined in the sub-claims to the main method claim.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in more detail in the following description of preferred embodiments with reference to the accompanying drawings, in which

FIG. 1 illustrates schematically a reflector according to known technology,

FIG. 2 illustrates schematically a preferred embodiment of the present invention, and

FIG. 3- 6 illustrates schematically other embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1, which illustrates the principle for recovering anaesthetic according to known technology, 1 denotes a patient being treated. The patient 1 is connected via the patient tube 2 to an anaesthetic first unit 6 arranged in a housing 10. This first unit 6 has the ability to absorb and desorb anaesthetic . In the same housing is a second unit 5 is arranged which can be either a filter or a heat and moisture exchanger or both. A supply tube 3 for anaesthetic, connected to a supply of anaesthetic 9, opens into the patient tube at 4. This opening can be with or without a porous unit which is substantially impervious to the gases, described as arrows, going to and from the patient. This porous unit, if used, can only take up a smaller part of the cross-section of the housing as otherwise the flow of gas to and from the patient will be hindered. The side of the first unit 6 is facing an outlet tube connected to a breathing system 7. This breathing system can be either a connection to the open air, an anesthesia apparatus, a ventilator or any other gas handling system to supply gas and take away gas to and from the patient. 8 is a gas monitor which monitors the gas concentration in the gas supply tube 2. This gas monitor can either work as a mainstream monitor, sensing the gas concentration, going to and from the patient, directly in the patient tube or a side-stream monitor sensing the gas concentration in a sample pumped from the patient tube. The function of this kind of gas monitors are well-known to those skilled in anesthesia or intensive care. The first unit 6 can be made of different materials like e.g. woven active carbon.

The device according to the invention illustrated in an embodiment shown in FIG. 2 is constructed in an equivalent manner to that shown in FIG. 1. Accordingly, the device shown in FIG. 2 illustrates a patient 1 connected via the patient tube 2 to first unit 6 arranged in a housing 10. This first unit 6 has the ability to absorb and desorb anaesthetic . In the same housing is a second unit 5, which can be either a filter or a heat and moisture exchanger or both, is arranged. The second unit 5 is highly porous and have a low gas flow resistance. A supply tube 3 for anaesthetic, connected to a supply of anaesthetic 9, opens into the patient tube at 4. This opening can be with or without a porous unit which is substantially impervious to the gases, described as arrows, going to and from the patient. This porous unit, if used, can only take up a smaller part of the cross-section of the housing as otherwise the flow of gas to and from the patient will be hindered. The side of the first unit 6 is facing an outlet tube connected to a breathing system 7. This breathing system can be either a connection to the open air, an anesthesia apparatus, a ventilator or any other gas handling system to supply gas and take away gas to and from the patient. 8 is a gas monitor which monitors the gas concentration in the gas supply tube 2. The arrangement with the second unit being placed in between the anaesthetic supply opening 4 and the patient results in the good distribution of the anaesthetic in the gas going to the patient and monitored by the gas monitor. In FIG. 2 both unit one and unit two are shaped as a cylindrical plates with axial through-flow. However, it will be understood that the shape is of minor significance. One or both of these units may be annular in shape, for instance, with radial through-flow direction, in which case fi^aπ^^enaeπdngHώrεldt^ll^rffiS.iSufeBaJecthffiicitt∞ivantageous from an economic manufacturing point of view as it contains few components but still obtains a very good distribution of anaesthetic.

The device according to FIG. 3 incorporates the same components designated by the same reference numerals shown in FIG. 2 but differs from that in FIG. 2 in that the porous unit at the opening 4 is formed as a cross giving an even better anaesthetic distribution in the gas going to the patient and monitored by the gas monitor 8. The device according to FIG. 4 incorporates the same components designated by the same reference numerals shown in FIG. 3 but differs from that in FIG. 3 in that the porous unit at the opening 4 is formed as a cylindrical piece, close to one of the sides of the housing.

The device according to FIG. 5 incorporates the same components designated by the same reference numerals shown in FIG. 2 but differs from that in FIG. 2 in that the opening 4 is touching the surface of unit two 5. This results in a good spreading of the anaesthetic inside the unit two 5 and thus a good distribution in the gas going to the patient and monitored by the gas monitor 8.

The device according to FIG. 6 incorporates the same components designated by the same reference numerals shown in FIG. 2 but differs from that in FIG. 2 in that the second unit 5 is made of two layers of material 5a and 5b laminated together with the opening 4 is touching the surfaces in between 5a and 5b. This results in a very good spreading of the anaesthetic inside the unit two 5 and thus a good distribution in the gas going to the patient and monitored by the gas monitor 8.

Although only a few embodiments of the device according to the invention have been described above and shown in the drawings it should be understood that the invention is not limited to these embodiments, but only by the limitations defined in the appended claims.

Claims

What is claimed is:

1. A device for recovering anaesthetic during the use of inhaled anesthetics, said device comprising a patient tube for connecting to a patient, a first unit capable of absorbing and desorbing anaesthetic preparations, a second unit capable of filtering a gas, both placed in a gas stream that goes to and from a human being or animal, most of this air stream passing through the first and second unit, and a tube which ends in between the first and the second unit and which supplies anaesthetic agent.

2. A device as claimed in claim 1, wherein said first unit and the second unit are arranged in a common housing.

3. A device as claimed in claim 2, wherein the tube is passing through the housing to the second unit.

4. A device as claimed in claim 1, where the first and the second unit are placed to touch each

5. Atdetøice as claimed in claim 2 where the first and the second unit are placed to touch each other.

6. A device as claimed in claim 3 where the first and the second unit are placed close to each other.

7. A device as claimed in claim 1 , where the first and second unit are made of the same material.

8. A device as claimed in claim 1, where the first and second material are made of different materials.

9. A device as claimed in claim 7 where the first and second unit are made of activated carbon fibers.

10. A device as claimed in claim 8 where the first or the second unit is made of activated carbon fibers.

11. A device as claimed in claim 7 where the first and second unit are made of a porous material capable of filtering most of the gases going back and forth to a human being or animal.

12. A device as claimed in claim 8 where the first and second unit are made of porous materials both capable of filtering most of the gases going back and forth to a human being or animal.

13. A device as claimed in claim 1 to 12 where the tube is ending on one of the edges of the second unit.

14. A device as claimed in claim 1 to 12 where the tube is ending inside of the second unit.

15. A device as claimed in claim 1 to 12 where the tube is supplying liquid anesthetic.

16. A device as claimed in claim 1 tn 12 where the tuhe is sunnlvinα αaseous anesthetic.

17. A device as in claim 1 where the second unit is comprising of two or more laminated layers to form one unit.

18. A device as in claim 17 where the tube is ending in between the layers.

19. A device as in claim 1 to 18 where the tube is also ending in a porous element through which the anesthetic is transported arid the gas going to and from the patient is flowing across at least one surface of the element.

20. A device as in claim 19 where, the porous element is made to distribute the anaesthetic evenly in the air stream going to dnd from the patient.

21. A method of recovering anaesthetic in an anesthesia circuit during the use of inhaled anesthetics, wherein the gases inhaled and exhaled by a patient are directed through a first unit for absorption of anaesthetic in the gas exhaled and desorptioh of anaesthetic to the gas inhaled, said method comprising providing a second unit in series with said first unit

, along said anesthesia circuit through which most of he gases are passing, a tube ending in between the first and the second unit and supplying anaesthetic to the gas to be inhaled in a patient along the anesthesia circuit.