GB1567325A - Sedimentation tests - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO SEDIMENTATION TESTS (71) We, GUEST MEDICAL AND DENTAL PRODUCTS A.G., a Swiss Company, of Weinbergstrasse 5, 6301 Zug, Switzerland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to sedimentation tests, and more particularly to the standard erthyrocyte sedimentation rate (ESR) test.

The ESR test consists in maintaining a column of blood with a specified anti coagulant, in a vertical position for a standard time, normally 1 hour to 2 hours, and noting the settlement of the red corpuscles or erythrocytes. In a healthy patient the settlement over such a period is limited, but the presence of infections leads to greater rate of settlement.

This test has been known to mankind for centuries and until recently, the column has been held up in the tubes by closing access to the top of the tube. Recently it has been found that a column of blood can be maintained by a plug of fibrous material inserted in the tube at the level of the required top of the column. The column is sucked up through the plug and allowed to sink back but will not pass the plug on the latter stage owing to capillary attraction between the blood and the plug.

The drawing of blood past the plug leads to a danger of drawing the column into the suction pump by which the column is drawn up the tube.

The present invention consists in apparatus for carrying out an ESR test com prising a tube to contain a column of liquid, a plug of fibrous material extending from a desired level of the top of the column to the upper end of the tube and a suction pump arranged to be connected to the top of the tube, in which the plug is of such a length and of such material and density that the pump can draw a column of liquid into but not through the plug.

In addition, the pump may have a filter to prevent accidental incursion of liquid in case of plug failure or otherwise.

The plug is preferably of cotton fibre.

The tube will normally be one of many set up in a stand, with their lower ends in individual samples of blood, and the pump will have a flexible hose at the suction side to be introduced briefly over the end of each tube successively. The tubes will normally be disposable and may be marked with a suitable scale to indicate the sedimentation level.

The invention will be further described with reference to the accompanying drawing, of which the single figure is an elevation of a plugged tube constituting a preferred embodiment of the invention.

The drawing shows a tube 11 for an ESR test, and as such it has to hold a column of blood 200mm long between a lower end 12 and a mark 13 indicating the top of the column. In the illustrated form, the tube 11 is graduated in mm and cm from 200mm at the bottom 12 to a 10mm mark 14 located lOmm below the mark 13. The calibration may be in the opposite direction. Extending upwards from the mark 13 to the upper end of the tube 11 is a plug 15 of cotton fibre which has a capillary attraction for the blood so as to prevent collapse of the column of blood once it has been drawn into the plug.The density of the plug and its length are chosen so that the pump which draws he blood into the column, and which is attached to the top of the tube by a flexible line, is not able in normal use to draw the column of blood right through the plug 15 and out of the upper end of the tube 11.

The blood soaks into the bottom of this plug but not through it. The plug therefore serves the following purpose: (1) to define the level to which the blood is drawn; (2) to absorb the blood sufficiently to main tain a column of blood for up to a minimum of 2 hours; (3) to prevent the blood from seeping into the pump connector or pump itself.

The extension of the plug to the top of the tube improves this; (4) the plug is sufficiently long so that there is no chamber above it in which blood may collect; and (5) since the plug is light in colour, it shows how far into it the blood has been absorbed so that it can be seen that the blood is never drawn through the plug.

By way of example only, the tube may be manufactured from clear polystyrene to an overall length of 230mm. As required for the standard Westergren ESR test, the internal diameter is 2.55mm + 0.15mm and the external diameter is approximately 6.0mm.

WHAT WE CLAIM IS:- 1. Apparatus for carrying out an ESR test comprising a tube to contain a column of liquid, a plug of fibrous material extending from a desired level of the top of the column to the upper end of the tube and a suction pump arranged to be connected to the top of the tube, in which the plug is of such a length and of such material and density that the pump can draw a column of liquid into but not through the plug.

2. Apparatus as claimed in claim 1, in which the pump has a filter to prevent accidental incursion of liquid.

3. Apparatus as claimed in claim 1 or 2, wherein the plug is of cotton fibre.

4. Apparatus as claimed in claim 1, 2 or 3, in which the tube is graduated with a scale to mark the sedimentation level.

5. Apparatus for carrying out a sedimentation rate test comprising a tube substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. The extension of the plug to the top of the tube improves this; (4) the plug is sufficiently long so that there is no chamber above it in which blood may collect; and (5) since the plug is light in colour, it shows how far into it the blood has been absorbed so that it can be seen that the blood is never drawn through the plug. By way of example only, the tube may be manufactured from clear polystyrene to an overall length of 230mm. As required for the standard Westergren ESR test, the internal diameter is 2.55mm + 0.15mm and the external diameter is approximately 6.0mm. WHAT WE CLAIM IS:-

1. Apparatus for carrying out an ESR test comprising a tube to contain a column of liquid, a plug of fibrous material extending from a desired level of the top of the column to the upper end of the tube and a suction pump arranged to be connected to the top of the tube, in which the plug is of such a length and of such material and density that the pump can draw a column of liquid into but not through the plug.

2. Apparatus as claimed in claim 1, in which the pump has a filter to prevent accidental incursion of liquid.

3. Apparatus as claimed in claim 1 or 2, wherein the plug is of cotton fibre.

4. Apparatus as claimed in claim 1, 2 or 3, in which the tube is graduated with a scale to mark the sedimentation level.

5. Apparatus for carrying out a sedimentation rate test comprising a tube substantially as hereinbefore described with reference to the accompanying drawing.