Method of photometric in vitro determination of the content of an analyte in ...

3 4

FIG. 7 shows the photometric basis for determination pie within one measuring chamber provided that each

of pH; individual analyte has an effect on the transmission

FIG. 8 is a perspective view of a sample container for properties of the transparent body and that each analyte

use in determining pH; affects the transmission properties differently.

FIG. 9 is a partial cross section of an optical unit in a 5 Such determination of several analytes within one

system comprising an analyzer according to the inven- measuring chamber may be accomplished by using a

tion and a sampling device according to the invention transparent body to which several indicators are fixed,

for photometric determination of pH and with a sche- The use of a transparent body containing a reagent

matic representation of the components forming parts which on reaction with the analyte forms a reaction

of the optical unit. 10 product changing the transmission properties of the

In the different figures like reference numerals desig- body in relation to the analyte concentration in the

nate like parts. environment of the body would be suitable for the de

DETAILED DESCRIPTION OF THE termination of certain analytes. In that case it may be

INVENTION the reaction product per se which changes the transmis

15 sion properties of the body or an indicator which is

"In vivo locality" denotes m the present context a flxed t0 the body ^ is affected by the reaction prodlocality being in direct connection with the blood circu- uct

lation or being a locality in the blood circulation itself. In particular) the method according to the invention

Sampling by arterial puncture, whereby the blood sam- ^ at such M Wood cationic and ^

pie is transferred from the artery to the sample con- 20 onic components in blood (blood electrolytes), metabo

tamer by a thin needle, as well as via an arterial catheter ^ hormones, enzymes, proteins, drugs and other

or via capiUary puncture are sampling methodologies, ... ies which i$ Qr fee f()und m blood

in which the blood sample is transferred directly from E les £ such ^ carbon dioxid

an in vivo locality to a sample container. „, , TM T . , xT , „, i,°, , , . TM

,. , r „ H+ (or pH), Li+, Na+, K+, Ca++, Mg++, CI-,

The radiation emitted from the radiation source may 25 , . ■ ■ , \ ± u-r u

„ , .. ,. HCO3-, urea, glucose, creatinine, lactate, bilirubm,

be broad banded as well as monochromatic radiation , , \ , . . , .' , jr. J4.

, . , . ,4 • , . . .,, cholesterol, triglycerides, and uric acid. Beyond this the

and may belong to the ultraviolet range, the visible . .. * , , •' , ^ ... _, •

r, ■ v J J / 4.U ■ r J invention particularly aims at any analyte mentioned in

range, the near infrared range and/or the infrared .. , , \. ..., J . . — J , 3 _ .... ,

range. The radiation source may comprise one compo- Mosbach, ^'ITM" TM,BTM7TM£F' iT^Z?

nent or several components emitting radiation at their 30 Enf ymes md Cells> Part D •137 <1988> P- ^ ^lbld

respective particular wavelength range. The radiation P" T ., ,

detector as well may comprise one component detect- . J In connection with determination of the carbon diox

ing radiation at a particular wavelength range or several lde cont*nt 18 Preferred a body made of silicone rubber

components detecting radiation at their respective par- or another transparent, homogeneous material with a

ticular wavelength ranges. The several components of 35 dissolution power for CG2. The C02 determina

the radiation source may be provided as one integrated tion is accomplished on the basis of testing the transmis

device or as separate devices. The same applies to the S10n properties of the body for 4.2 urn radiation. The

radiation detector. basic principles for such determination are disclosed in

The controlled deformation of the sample chamber is the specification of British patent application GB

a deformation reducing the volume of the measuring 40 2160646 and in the specification of European patent

chamber to such extent that the measuring chamber is application EP 253559.

either completely or locally drained for blood sample. In connection with determination of pH is preferred a By "local draining" is understood that the part of the body made of a polymer material with —OH groups measuring chamber traversed by the radiation is available for immobilization, e.g. a cellulose or cellodrained for blood sample. 45 phane material, and with a pH indicator which may be

In a preferred embodiment of the method according covalently bound thereto, e.g. an indicator comprising

to the invention the optical communication is estab- tne reactive group — SO2—CH2—CH2—O—SO3H.

lished by placing the sample container in a sample con- Cellophane in particular has physical properties suitable

tainer station of an analyzer. for the present purpose, such as a well-defined thickness

Alternatively, the optical communication may be 50 and a homogeneous structure, established by one or several cables which via means for The invention also relates to a sampling device corncontacting the sample container and optical fibres estab- prising a sample container with a measuring chamber lish optical communication between the optical system having at least locally transparent opposite wall parts and the sample container. and having the characteristic features of controlled

The transparent body used in the method according 55 deformable wall parts that are deformable such that the

to the present invention is made of a material with a measuring chamber is substantially drained of blood

homegeneous structure, in particular a homogeneous sample on normal use of the sampling device,

surface making the material suited for use in photomet- Preferably, the locally transparent wall parts com

ric transmission analysis. Preferably, the body is shaped prise planoparallel parts extending parallel with the

as a disc or plate with two planoparallel surfaces and a 60 planoparallel surfaces of the transparent body. By such

thickness of less than 1 mm, preferably 1-500 jim, in configuration is ensured that the drainage of the mea

particular 5-250 fim and most preferably 8-200 fim. suring chamber is readily obtained, viz. by pressing the

If an indicator is fixed to the transparent body the wall parts against the transparent body. The transparent

indicator may be fixed by any suitable immobilization body may be loosely accomodated in the measuring

method such as by absorption, adsorption, ion binding 65 chamber or it may be fixed to a wall part,

or covalent binding. Other preferred embodiments of the sampling device

Conceivably, it will be possible to make a determina- according to the invention have the characteristic fea

tion of the content of several analytes in the blood sam- tures set forth in the dependent claims.

5 6

The sample container may comprise one measuring controls the sampling device to a desired temperature,

chamber or several measuring chambers disposed in preferably app. 37° C.

series or in parallel. Preferably the sample container is Closing the cover 8 further results in a signal being

made of an injection mouldable polymeric base mate- sent to the controlling unit of the analyzer and indicat

rial, e.g. the material sold under the trade name AR- 5 ing the start of an analysis procedure. An operator can

NITE TM from AKZO, Arnheim, Holland. control the operation of the analyzer by means of a

In connection with the performance of a pH or a keyboard 5 and a display 6. The analyzer 11 preferably

carbon dioxide determination on a blood sample in the also comprises a printer, which can produce an outprint

measuring chamber the wall parts of the measuring 7 of i.a. the analysis results obtained by the analyzer,

chamber are preferably made of a polymer material 10 After placing the sampling device 2 in the sample

having a low carbon dioxide permeability and suitable container station 1 and closing the cover 8 of this, the

transmission properties for radiation at the wavelengths optical components comprising of radiation sources and

relevant to the above-mentioned determinations, said radiation detectors are activated, whereupon the analy

wavelengths being discussed at another page. A suitable zer 11 calculates one or several parameters on the basis

material is an ethylene vinylalcohol copolymer of the 15 of the signals from the radiation detectors. The result of

type EVAL-E TM sold by Kuraray Co., Osaka, Japan. the calculations is displayed on the display 6 and is

In the case where the blood sample is provided by printed on the paper outprint 7 by the printer. When the

capillary puncture, the use of a sample container with a calculations are terminated and the results displayed

dimension sufficiently small for the sample container to and/or printed out the cover 8 is opened and the sam

be filled by capillary effect is preferred. 20 pling device 2 is displaced from the sample container

In the case where a sample of arterial blood is desired, station 1 and disposed of.

the use of a sample container with an inlet located in a In a larger scale FIG. 2 shows a partially schematic

coupling means, preferably a Luer cone, for coupling section of the sample container station 1 viewed from

the sample container to a needle or a catheter is pre- above. As shown the optical section 3 comprises four

ferred. 25 optical units 30, 40, 50, and 60 adapted for determina

The invention further comprises an analyzer for use tion of pH (unit 30), carbon dioxide (unit 40), oxygen

in the method according to the invention, said analyzer (unit 50) and hemoglobin and oxygen saturation (unit

having the characteristic features of means further 60) respectively. The sample container of the sampling

adapted to deform the measuring chamber such that the device with four measuring chambers is placed in a slot

measuring chamber part located in the radiation trans- 30 4 in the optical section 3.

mission path is essentially drained of blood sample. Even though the analyzer 11 is shown containing

In a preferred embodiment the analyzer comprises four optical units it can in principle contain an arbitrary

data processing means for processing the registered number and/or an arbitrary combination of units be

radiation data for deriving the content of the actual yond the unit utilized in the method according to the

analyte in the actual sample from these. Alternatively 35 invention.

the analyzer is adapted for connection to a separate data FIG. 3 shows a longitudinal section of the sampling

processing unit. device 2 and four segments of this in a larger scale. The

In a further preferred embodiment of the system sampling device comprises a body 23, which at least in

according to the invention the analyzer comprises specified areas is made of a material transparent for the

means for displaying the analyte content. Alternatively, 40 relevant radiation. The body 23 has a continuous con

the analyzer is adapted for connection with means such duit 22 locally extended for forming measuring cham

as, e.g. a data screen, a display, a printer, or a plotter. bers 300,400, 500, and 600. During a course of measure

The invention will now be explained in the following ment the actual blood sample fills the conduit 22 from

with reference to the drawings and the subsequent ex- its inlet aperture 21 to a hydrophobic filter 24 placed

amples. In the drawings 45 behind the measuring chambers. The section of the

The analysis system shown in FIG. 1 and generally body 23 surrounding the inlet aperture is provided with

designated 10 is a compact portable "stand-alone" sys- a Luer cone and is therefore suitable for being mounted

tem, which is suited for decentral use, i.e. use outside a with a needle 20 of the type normally used for blood

regular laboratory environment, e.g. in an operating sampling. The section 25 of the body 23 pointing away

room or at an intensive ward. The analysis system 10 50 from the inlet aperture is adapted for coupling with a

comprises a blood sampling device 2 for disposable use traditional plunger syringe. Such a plunger syringe is

and used in connection with an analyzer 11. The sam- used as aid at the sampling in certain situations, e.g.

pling device 2 is more explicitly described in connection when the patient, whose blood gas parameters are to be

with the description of FIGS. 3-5 below. The sampling determined, has a very low blood pressure,

device 2 and the analyzer 11 are adapted to interact in 55 When the sampling device 2 is placed correctly in the

the way that the analyzer 11 has a sample container sample container station 1, the measuring chambers 300,

station 1 with an optical section 3 adapted for receiving 400, 500, and 600 communicate optically with the opti

the sampling device 2 or possibly the sample container cal units 30, 40, 50, and 60. The measuring chamber 300

of the sampling device, so that the optical communica- optically communicating with the optical unit 30 is

tion between the sampling device 2 and the optical 60 adapted for determination of pH in the blood sample

components of the optical unit 3, which is necessary for and contains a cellophane membrane 316, to which is

photometric analysis, is obtained. immobilized a pH absorbance indicator. When the indi

The sample container station 1 can be closed by a cator is in chemical equilibrium with the blood sample,

cover 8, which is closed after placing the sampling the ratio between the acid form of the indicator and the

device 2 in the station. By closing the cover 8 different 65 basic form of the indicator reflects the pH value of the

mechanisms are activated, e.g. a not shown clamping blood sample. The chemical and photometric basis for

mechanism, which secures the sampling device 2 in the the pH determination appears from FIG. 7, 8, and 9 and

optical section 3 and at the same time thermostatically of the description of these. An embodiment of the opti