ANALYSIS DEVICE FOR ANALYZING EXPIRATION AIR

Abstract

An analysis device for analyzing expiration air of a patient, preferably for monitoring a patient under anesthesia during a medical intervention, is configured for determining, in the expiration air, a portion of an analyte contained in the expiration air. The analysis device preferably has a multi-capillary column for separating the expiration air to be analyzed and an ion mobility spectrometer in which gas components of the expiration air are ionized and accelerated toward a detection device. The analysis device can output signal excursions which are created by the ionized gas components of the expiration air which hit the detection device. A portion of the analyte which is to be determined and is contained in the expiration air to be analyzed is determined by a calibration of the signal excursion of the analyte to a signal excursion which is caused by the air moisture of expiration air.

Claims

1. An analysis device adapted for analyzing expiration air of a patient, the analysis device being configured to determine, in the expiration air, a portion of an analyte in the expiration air, the analysis device comprising: at least one multi-capillary column adapted for pre-separating the expiration air; and an ion mobility spectrometer in which gas components of the expiration air are ionized and accelerated towards a detection device, the analysis device being adapted to output signal excursions which are created by ionized gas components of the expiration air which hit the detection device, the analysis device being adapted to determine a portion of the analyte which is to be determined and is contained in the expiration air analyzed by calibration of the signal excursion of the analyte to a signal excursion which is caused by an air moisture of the expiration air.

2. The analysis device according to claim 1, wherein a maximum signal excursion of the analyte is put in relation to a maximum signal excursion of the signal excursion caused by the air moisture of the expiration air, and the portion of the analyte in the expiration air is determined based on a known and constant relative air moisture of expiration air.

3. The analysis device according to claim 1, wherein the analysis device is configured to carry out measurement of a portion of the analyte in the expiration air by calibration of the signal excursion of the analyte to the signal excursion caused by the air moisture of the expiration air with continuously increasing absolute signal excursions and thus immediately after turning on the analysis device.

4. The analysis device according to claim 1, wherein the analyte to be determined is an anesthetic.

5. The analysis device according to claim 4, wherein the analysis device is configured to establish the portion of the anesthetic in the expiration air at predetermined short time intervals, and to indicate measuring values obtained on a display.

6. The analysis device according to claim 1, wherein the gas components of the expiration air take differently long for a passage through a multi-capillary column and a passage time through the multi-capillary column is referred to as retention time; wherein the ion mobility spectrometer has an ionization chamber section in which the gas components of the expiration air are ionized and a drift chamber section in which the ionized gas components are accelerated toward the detection device, and a passage time through the drift chamber section is referred to as drift time; and wherein the analysis device outputs the signal excursions in a chromatogram as a function of the retention time and the drift time.

7. The analysis device according to claim 6, wherein the signal excursion caused by the air moisture of the expiration air is provided in the chromatogram substantially independently of the retention time after a particular drift time and represents a maximum signal excursion in the chromatogram.

8. The analysis device according to claim 6, wherein the signal excursion caused by the air moisture of the expiration air is created by reaction ions formed during ionization of the expiration air and hitting the detection device which excel by a characteristic signal excursion in the chromatogram.

9. The analysis device according to claim 6, further comprising a database in which two values each for the drift time and the retention are stored for different analytes, wherein said values stored in the database define a range in the chromatogram in which the signal excursion for a particular analyte is provided, wherein a drift time axis is scaled to the signal excursion caused by the air moisture of the expiration air.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0021] The invention shall be further explained hereinafter by way of figures, wherein:

[0022] FIG. 1 shows a schematic view of an analysis device according to the invention;

[0023] FIG. 2 shows a three-dimensional view of a chromatogram in which signal excursions are shown as a function of a drift time and a retention time; FIG. 3 shows a two-dimensional view of a chromatogram in which signal excursions are shown

[0024] as a function of the drift time and the retention time;

[0025] FIG. 4 shows a display of the analysis device according to the invention; and

[0026] FIG. 5 shows a flow diagram of steps to be carried out until the analysis device according to the invention is ready for measuring.

DETAILED DESCRIPTION

[0027] The figures a merely schematic and serve exclusively for the comprehension of the invention. Like elements are provided with like reference numerals.

[0028] FIG. 1 illustrates a schematic view of an analysis device 2 according to the invention. The analysis device 2 includes a multi-capillary column 4 and an ion mobility spectrometer 6. The multi-capillary column 4 consists of a plurality of bundled individual capillaries (not shown). Different gas components of expiration air take differently long for passing through the multi-capillary column 4. Expiration air which is expired by a patient 8 and is supplied to the multi-capillary column 4, as shown in FIG. 1, thus is divided into individual gas components with the aid of the multi-capillary column. The time required by a gas component for passing through the multi-capillary column 4 is referred to as retention time t.sub.R.

[0029] After a first separation by means of the multi-capillary column 4 the expiration air and, resp., the gas components thereof is/are supplied to the ion mobility spectrometer 6. The ion mobility spectrometer 6 comprises an ion chamber portion 10 and a drift chamber portion 14 adjacent thereto and separated from the ionization chamber portion 10 by a Bradbury-Nielsen grid 12. In the ionization chamber portion 10 the gas components of the expiration air are ionized by means of an ionization source 16 (for example radioactive nickel). The Bradbury-Nielsen grid 12 controls penetration of the ions generated in the ionization chamber portion 10 into the drift chamber portion 14. Via an electric field generated by means of high-voltage rings 18 the ions are accelerated toward a Faraday plate 20 which serves for detecting the ions. Directly ahead of the Faraday plate 20, an aperture grid 22 is provided as a shielding grid for capacitive uncoupling of the ions. On the side of the drift chamber portion 14 including the Faraday plate 20, an inlet opening 24 for a drift gas is provided which flows through an interior 26 opposite to a drift direction of the ions and prevents uncharged molecules or particles from entering into the drift chamber portion 14.

[0030] Ions of different mass and, resp., structure reach different drift velocities in the drift chamber portion 14, are thus separated from one another (second separation) and successively hit the

[0031] Faraday plate 20. A passage time of the ions through the drift chamber portion 14 is referred to as drift time t.sub.D.

[0032] The analysis device 2 is configured to determine, in the expiration air, a portion of an analyte contained in the expiration air. In the present invention, the analyte to be determined preferably is an anesthetic, preferably propofol, which was administered intravenously to the patient 8 and which the latter exhales under anesthesia via the expiration air.

[0033] The accuracy with which the portion of the analyte contained in the expiration air is determined according to the invention is explained with reference to FIG. 2. FIG. 2 illustrates a chromatogram which exemplifies two signal excursions that are created by ionized gas components hitting the Faraday plate 20 and are output by the analysis device 2 as a function of the retention time t.sub.R and the drift time t.sub.D.

[0034] FIG. 2 illustrates a first signal excursion 28 and a second signal excursion 30. The first signal excursion 28 is caused by the air moisture of the expiration air, especially by reaction ions, especially H.sup.+(H.sub.2O).sup.n ions or O.sub.2.sup.(H.sub.2O).sup.n ions, formed when the expiration air is ionized and hitting the Faraday plate 20. Said first signal excursion 28 is present substantially independently of the retention time after a particular drift time in the chromatogram and constitutes, due to the high relative moisture of expiration air of more than 95%, in an analysis of expiration air always a maximum characteristic signal excursion in the chromatogram.

[0035] The second signal excursion 30 is caused by an analyte (for example an anesthetic, preferably propofol) the portion of which in the expiration air has to be determined.

[0036] According to the invention, initially a first maximum (absolute quantitative value) 32 of the first signal excursion 28 is determined. Subsequently, a second maximum (absolute quantitative value) 34 of the second signal excursion 30 is determined. To obtain the portion of the analyte in the expiration air, for example the ratio between the second maximum 34 and the first maximum 32 is formed and is multiplied with the known and constant air moisture portion of the expiration air of the patient 8. In other words, according to the invention calibration of the second maximum 34 of the second signal excursion 30 to the first maximum 32 of the first signal excursion 30 is carried out.

[0037] In FIG. 2, broken lines indicate another first maximum 32 of the first signal excursion 28 and a second maximum 34 of the second signal excursion 30. The first maximum 32 and the second maximum 34 would be obtained, if the same expiration air sample was supplied once again to the analysis device 2 to a later point in time. In other words, basically with an increasing period of time after turning on the analysis device 2 increasing maximums 32, 34 of the signal excursions 28, 30 are obtained. The present invention allows to appropriately treat continuously increasing absolute signal excursions as, according to the invention, in each case only the ratio between the second maximum 34, 34 and the first maximum 32, 32 has to be formed.

[0038] FIG. 3 illustrates a two-dimensional view of the chromatogram obtained in which different signal excursions obtained, for example again the signal excursions 28 and 30 shown in FIG. 2, are shown. As explained already before, the signal excursion 28 represents a signal excursion characteristic of the moisture and can be found in a simple way as it is provided after a particular drift time t.sub.D independently of the retention time t.sub.R.

[0039] The analysis device 2 includes a data base 36 in which two values each for the drift time t.sub.D and the retention time t.sub.R are stored for different analytes to be determined. In the chromatogram said four values define a rectangular area 38 in which the signal excursion for a particular analyte is provided. Of preference, the values for the drift time t.sub.D are standardized to the first characteristic signal excursion 28.

[0040] When the second maximum 34 of the second signal excursion 30 is to be determined, the rectangular area 38 is defined in the chromatogram by the values obtained in the data base 36 and only the maximum/the maximum absolute value has to be determined in the defined rectangular area 38.

[0041] As shown in FIG. 4, the analysis device 2 measures/calculates/establishes, for example, every minute a portion ppb (parts per billion) of an analyte, preferably of an anesthetic, in the expiration air of a patient and outputs the portion obtained in each case on a display. Thus, a physician is allowed to continuously analyze the portion of the anesthetic (propofol) in the expiration air and to monitor the patient under anesthesia during a medical intervention. For example, the physician can repeatedly administer the anesthetic intravenously to the patient 8, when he/she notices after 6 minutes or 7 minutes as shown in FIG. 4 that the portion of the anesthetic in the expiration air subsides.

[0042] FIG. 5 illustrates a flow diagram of steps to be carried out until the analysis device 2 according to the invention is ready for measurement. Turning on the device is followed by initialization, a heating phase, flushing and a reference measurement. Said steps take less than 30 minutes. Where it has been mentioned in the foregoing that measurement of a portion of the analyte in the expiration air can be carried out immediately after turning on the analysis device 2, this shall mean that measurement of a portion can be carried out after 30 minutes at the latest.