Apparatus for measuring the rate of erythrosedimentation of the blood

In an apparatus for measuring the rate of erythrosedimentation of the blood a bell mouthed test tube is provided, having a cylindrical part in which a calibrated and graduated sealing tube, topped with an overflow sleeve for the excess blood, slides. This overflow sleeve allows an automatic filling with blood of the calibrated tube independently from the care taken in the filling of the tapered test tube.

Many different apparatuses are known for measuring the rate of 
erythrosedimentation of the blood (Katz factor). 
One known method in the determination of the rate of erythrosedimentation 
(E.S.R.) is the Westergren method. 
The blood obtained from venopuncture is immediately mixed in the proportion 
of 4 volumes of blood to 1 of Sodium Citrate. The blood is introduced in a 
calibrated tube which is placed in a vertical position in a suitable 
support. After the first and the second hour, the height of the formed 
plasmatic column is read. 
In Italian Pat. No. 721.410, compare parent U.S. Pat. No. 3,373,601 and 
G.B. Pat. No. 2.048.836, the oral aspiration of the blood is obviated by 
manufacturing the test tube with an internal sealing rim which cooperates 
in the manner of a piston gasket with the blood of the graduated tube. The 
graduated tube receives blood from the test tube leaving an air space in 
such a way that, by adjusting the volume of the air space, it is possible 
to bring the blood level to zero (0), (having made the tube touch the 
bottom of the test tube). It will be understood that such a method has 
different inconveniences both in the moulding and in function, for the 
stated reason that adjusting operations are necessary in order for the 
level of the blood to reach, with its meniscus, the zero (0) reference 
graduation. 
The object of the invention is to reduce or obviate in a practical way the 
above mentioned inconveniences by proposing an apparatus for measuring the 
rate of erythrosedimentation (E.S.R.) of the blood, characterized in that 
it comprises a test tube (PR) having a cylindrical portion (PC.sup.1), a 
calibrated tube (TC) dimensioned to be a sliding and sealing fit in the 
cylindrical portion (PC.sup.1) of the test tube (PR), the top of said 
calibrated tube (TC) being provided with an overflow sleeve (BS) for 
receiving, in use, excess blood from the test tube.

With reference to the drawings, PR indicates a test tube of transparent 
plastic material having a perfectly cylindrical part PC.sup.1 which 
prolongs itself with another cylindrical part PC.sup.2 of greater 
diameter. The two portions adjoin in correspondence of a conical trunk 
part TK with a knurled border ZR which in one way acts as a reference line 
and in another way permits to obviate the blood surface tension so as to 
facilitate the mixing of blood/anticoagulant. 
TC indicates a graduated and calibrated tube hereinafter mentioned as 
"pipette" also made of transparent plastic material, the external diameter 
of which is such that it will slide and seal along the cylindrical part 
PC.sup.1. 
The pipette is, preferably, perfectly, transparent, without visible defects 
or internal striations. 
The graduated scale in mm. extends for 150.+-.0.35 mm. from one extremity 
to the other of the vertical axis. 
Generally, the test tube PR is filled in advance with an anticoagulant AC 
and closed with a stopper TP of flexible material in such a way to permit 
an hermetic sealing of the test tube. 
According to a very important characteristic of the invention, a sleeve BS 
is provided which is mounted and sealed in correspondence of the extremity 
ES of the pipette and presents a small canal CN which projects out in 
respect to a diaphragm DF in such a way that it extends on one side in the 
tube (pipette) and on the other in a chamber CM forming an excess overflow 
tank. 
The apparatus functions as follows: 
First of all the stopper TP is removed (or pierced) and then the test tube 
PR is filled with blood up to the knurled zone ZR; the filling is executed 
with some approximation in excess for reasons which will emerge further 
on. The calibrated tube (pipette) TC is then introduced in the part 
PC.sup.1 and consequently the blood will rise up inside said pipette. 
Supposing, as is verified in the majority of the cases, that the volume of 
the blood is greater than the internal volume of the pipette, the excess 
blood will flow through the canal CN and it will be deposited in the 
chamber CM assuring, for this reason, a constant level of blood 
independently of the care taken in filling with the blood the test tube 
PR. In fact, after the simple operation of introducing the pipette TC all 
the way down until it is arrested by the bottom FO of the test tube, an 
operator does not have to execute any other operation or adjustment and 
this is positively reflected not only in the exactness of the measurement 
of the rate of erythrosedimentation, but also in the rapidity of the 
measure itself. 
It is observed that the test tube does not have any sealing rim. Therefore, 
the manufacturing or moulding requirements are remarkably simplified and 
every moulding tolerance (pipette calibration) is practically compensated 
by the excess overflow sleeve BS. 
It is also observed that the filling of the test tube with blood is not 
critical. 
In the case of a great excess of blood, the bell mouthed part PC.sup.2 of 
the test tube serves as an excess blood tank without affecting the 
accuracy of the measurement in as much that the blood which flows into the 
calibrated tube (pipette) is always the same volume as the internal 
portion PC.sup.1 thanks to the continuous seal of the pipette along the 
portion PC.sup.1. 
The overflow sleeve will be manufactured in a plastic material so as to be 
mounted on the calibrated tube (pipette) and will be constituted of 
materials not necessarily transparent. 
In order to prevent excess blood from being sprayed externally with the 
risk of contaminating the room, the overflow sleeve can be provided with a 
cap TA which has a hole FR so as to prevent the "cap" function from 
negatively affecting the value of the measure. 
The cap TA can be connected to the overflow sleeve by means of an isthmus 
so as to form a single unit. 
According to an important characteristic , the diameter of the entrance 
cone CE of the sleeve is proportioned in such a way that it may intercept 
the flow of the erythrocytes and function as a barrier for the same, that 
cannot longer influence the value of the measure. 
As seen from FIG. 6, a stand ST in a transparent plastic material is 
provided in which the test tubes PR are received and kept in a vertical 
position, and touching the work bench top when inserted in the stand. 
The concept of the invention can also be expressed according to the 
variation of FIG. 4. In this realization the overflow sleeve BS.sup.1 
presents an obturator OT which cooperates with the canal KA of the 
pipette, said obturator being completed with a milling CN.sup.1 equivalent 
to the canal KA and proportioned in such a way as to prevent the reflux of 
the blood. The sleeve presents a vent hole FR.sup.1 and its bottom 
TA.sup.1 functions as a cap (anti-spray). The sleeve presents some arrest 
counter shoulders SP in a rib formation. 
The test tube may be filled with blood without removing the cap TP: in 
effect as provided by the same Applicant in Italian Patent Application No. 
30952 A/76 filed on 29th Dec. 1976, the bottom BT of the cap TP may be of 
perforable kind and the end of the calibrated tube test tube to the "zero" 
location may be tapered TT in order to secure a prompt perforation. The 
bottom portion FO of the test tube may be provided with a conical 
projection CP in order to secure a tight obturation of the calibrated tube 
with the cylindrical portion of the tube, thus obviating possible moulding 
deficiencies.