2. sedimentation rate

plumbergamΜηχανική

22 Φεβ 2014 (πριν από 3 χρόνια και 8 μήνες)

62 εμφανίσεις

P R A C T I C A L T R A I N I N G I
N P H Y S I O L O G Y

O F B L O O D

1

1.

VENIPUNCTURE



Most routine hematological studies are performed on venous blood, which is usually
obtained from an antecubital vein. Occasionally, in very obese persons or those whose veins have
been thrombosed by chemotherapy, it may be necessary to punct
ure one of the veins on the
forearm or on the dorsum of hand.


Materials:



Cotton swab



Disinfectant (Ajatin)



Tourniquet



Sterile plastic disposable syringe and sterile disposable needle



Plaster


Procedures:

1.

Attach a sterile needle with its cover to the syrin
ge.

2.

Apply a tourniquet round the upper arm over the middle of the biceps.

3.

Choose a vein for venipuncture. It should be straight, not tortuous, and should be well
fixed in the subcutaneous tissue so that it does not roll away. Patient's arm should be
extend
ed.

4.

Carefully clean the skin at the cubital fossa with a swab soaked in Ajatin.

5.

Stretch the skin at the cubital fossa by one hand. Push the needle with the syringe
attached through the skin and then slowly into the prominent vein with the opposite hand.
Th
e direction of the needle should be almost parallel with the vein chosen for obtaining
blood.

6.

Try to draw up small amount of blood into the syringe to make sure that you managed to
puncture the vein.

7.

Remove the tourniquet and draw up amount of blood requir
ed.

8.

Withdraw the needle from the vein and immediately place a swab on the puncture site.
Instruct the patient to hold his forearm firmly flexed against his arm for a minute or so.

9.

Strap the puncture site.

10.

Blood obtained by venipuncture place immediately in
to a specimen container suitable for
the particular test required.


CAUTION:
Procedure of blood manipulation should be slow and careful because of easy
damage to blood cells and hemolysis. Hemolysed blood should not be used for many kinds of
blood tests. I
t is necessary to remove the needle before releasing obtained blood into a container.
The needle used for obtaining blood should be sharp and it should have sufficient diameter.


2.

SEDIMENTATION RATE

(ACCORDING TO FAHRAEUS AND WESTERGREEN)



If the blood is
kept fluid by means of an anticoagulant and is allowed to stand in a narrow
tube, the corpuscles settle progressively to the bottom leaving clear plasma above. The rate at
which this takes place is known as sedimentation rate. Normally the sedimentation ra
te is 2


5

mm/hour in males and 3
-

8 mm/hour in females.


P R A C T I C A L T R A I N I N G I
N P H Y S I O L O G Y

O F B L O O D

2

Materials:



Citrated human blood (1 part of sodium citrate 3.8 % and 4 parts of blood)



Wintergreens sedimentation apparatus with narrow graduated tube


Procedures:

1.

Fill the tube with citrated blood

to the 0
-
mm mark.

2.

At the end of one and two hours read the height in mm of the column of clear plasma. See
figure 1.

3.

Compare your result with normal values.




Figure 1.


Wintergreens sedimentation apparatus:

a) before filling, b)
initial adjustment
-

Wintergreen’s narrow tube filled with blood to 0 mm mark, c) after
one hour
-

sedimentation rate as height in mm of the column of clear plasma = 5 mm/h

P R A C T I C A L T R A I N I N G I
N P H Y S I O L O G Y

O F B L O O D

3

Results:




Conclusion:





3.

HEMATOCRIT DETERMINA
TION



The test specifically measur
es the relative volume of erythrocytes in the blood. The
hematocrit value is 44


5 % for men and 39


4 % for women.


Materials:




Non
-
coagulating human blood (with sodium EDTA as the anticoagulant)




Heparinized capillary tubes




Laboratory burner




Safety
matches




Hematocrit centrifuge




Hematocrit reader


Procedures:

1.

Allow the blood to fill 4/5 of two capillary tubes.

2.

Seal the free end of the tubes in the flame of a laboratory burner.

3.

Place the tubes in a hematocrit centrifuge with the sealed ends directed
outward, one
opposite the other.

4.

Secure the top of the centrifuge and spin for 2 minutes at 16 000 r.p.m. (revolutions per
minute).

5.

Remove the tubes from the centrifuge and determine the hematocrit value as the ratio of
packed cells to the total blood volu
me according to figure
2
.

6.


Compare your value with physiological (standard) values.


Results:





Conclusion:



P R A C T I C A L T R A I N I N G I
N P H Y S I O L O G Y

O F B L O O D

4



Figure 2.


Hematocrit reader: a) initial adjusting, b) hematocrit reading

4.

DETERMINATION OF MCH
, MCHC, MCV


MEAN CELL
HEMOGLOBIN

(average amount of hemoglobin per cell)



mean cell hemoglobin
hemoglobin in grammes per litre of blood
red cells count per litre



Normal values are 28
-

32 pg.


MEAN CELL HEMOGLOBIN CONCENTRATION

(amount of hemoglobin in 1 liter of red corpuscles)


mean cell hemoglobin concentration
=

hemoglobin in grammes per litre of blood
hematocrit



Normal values are 300
-

350 g/l. If the c
orpuscular hemoglobin concentration is within the
normal range the cell is normochromic; if it is below the normal range the cell is hypochromic.


MEAN CELL VOLUME

mean cell volume
=

hematocrit
red cells count per litre


The normal range is 85


10 fl. Cells of average volume are called norm
ocytes; cells whose
volume exceeds the normal range are called macrocytes, while small cells are called microcytes.



Calculate the MCH, MCHC, and MCV in the following cases:

P R A C T I C A L T R A I N I N G I
N P H Y S I O L O G Y

O F B L O O D

5

1)
woman, 29 years old, red cells

count:

4
.
3

x 10
12
/l; hematokrit 0
.
38; hemoglobi
n 1
3
2 g/l

2) man, 55 years old, , red

cells

count:

4
.25

x 10
12
/l; hematokrit 0
.
3
2
; hemoglobin 1
08

g/l


Results:











Conclusion:



5.

QUICK’S PROTHROMBIN
TIME



This is a test for deficiency in clotting factors I, II, V, VII, X in vitro because prothromb
in
-

to
-

thrombin reaction proceeds here by means of the extrinsic clotting pathway. The normal
human prothrombin time is approximately 12 seconds and the length of its duration is used to
control clotting in patients treated with vitamin K antagonists (f
or example dicoumarol). Their
administration prolongs Quick’s prothrombin time.


Materials:



Citrated human blood (9 parts of blood, 1 part of sodium citrate 3.8 %)



Normal saline



Test tubes



Reagent (CaCl
2
solution and tissue thromboplastin)



Pasteur’s pipett
e



Pipettes



Water bath (37
o
C)



Glass stick


Procedures:


1.

Centrifuge citrated blood for 5 minutes at 3 000 r.p.m.

2.

Separate plasma with Pasteur’s pipette.

3.

Mix 0.1 ml plasma and 0.2 ml reagent. All ingredients are incubated at 37°C. The time
taken for fibrin t
hreads to form after the addition of reagent is measured.

4.

Make this test also with 50 % (one part of 100 % plasma, one part of normal saline), and
25 % (one part of 50 % plasma, one part of normal saline). With plasma dilution the
concentration of blood c
lotting factors falls and blood coagulability is depressed, Quick’s
prothrombin time is prolonged.

5.

Construct the curve showing the relationship between prothrombin time and plasma
dilution.

P R A C T I C A L T R A I N I N G I
N P H Y S I O L O G Y

O F B L O O D

6

Results:




Graph:




Conclusion:





6.

FRAGILITY OF RED COR
PUSCLES IN HYPOTONIC

SALINE



Because of the higher osmotic pressure inside the cells in hypotonic saline, fluid passes into
the corpuscles until they burst and their hemoglobin is liberated. Normally hemolysis begins in 0.4
% NaCl (m
inimal
resistance
)
-

old erythrocytes are only destroyed
,

and
it
is complete at 0.3 %
NaCl (maximal
resistance
).


Materials:



Non
-
coagulating human blood (an anticoagulant: sodium EDTA)



Test tubes with distilled water



1 % NaCl



Pipettes



Pasteur’s pipette


Pr
ocedures:

25%

50
%

100
%

P
lasma dilution

Time (sec)

P R A C T I C A L T R A I N I N G I
N P H Y S I O L O G Y

O F B L O O D

7

1.

Prepare a series of hypotonic NaCl solutions in a set of test tubes, using 1 % NaCl
solution and distilled water. See table 1:


Distilled

water:

(ml)

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5


1 % NaCl

solution:

(ml)

4.5

4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5


Final concentration of NaCl:

(%)

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1


Table 1.


2.

Add one drop of blood to every test tube and gently mix.

3.

Allow the tubes to stand for approximately 2 hours and after this exposure observe the
content of tubes. Ery
throcyte sediments and colorless NaCl solutions above them are seen
in tubes with isotonic and slightly hypotonic NaCl. When hemolysis begins, red NaCl
solution is visible above the erythrocyte sediment (read

minimal osmotic resistance
). All
erythrocytes r
uptured in tubes with red NaCl solution without any sediment. The highest
concentration of NaCl with complete hemolysis is denoted as
maximal osmotic resistance
.
See figure
3
.

4.

Compare your results with physiological values.




Figure 3.


Test tubes with erythrocytes in hypotonic NaCl: a) erythrocyte sediment + colorless NaCl solution, b) erythrocyte
sediment + red NaCl solution (minimal fragility), c) red NaCl solution without erythrocyte sediment (maximal
fragility)


Results:




Con
clusion:



P R A C T I C A L T R A I N I N G I
N P H Y S I O L O G Y

O F B L O O D

8

7.

BLOOD TYPING



Blood typing is based upon the presence of certain antigenic substances localized on the
red cell membrane. The
most powerful

antigens comprise the AB0 series. Other substances found
on the erythrocyte membrane define the Rh serie
s.


Materials:



Cotton



Disinfectant (Ajatin)



Sterile needles



Paper cards



Microscope slides



Anti
-
A, anti
-
B, and anti
-
Rh (anti
-
D) blood sera


Procedures:

1.

Disinfect your finger with Ajatin, allow it to dry, and puncture with a sterile needle.

2.

Allow one drop of

your blood to fall into each of two large circles on the paper card (see
figure
4
) and one drop on a microscope slide.

3.

Carefully place one drop of anti
-
A serum in first small circle, one drop of anti
-
B serum in
second small circle, and two drops of anti
-
R
h serum on the slide.




Figure 4.


Paper card for blood typing in the AB0 series


4.

Mix the blood and anti
-
sera with corners of the slide and observe results. Agglutination
should occur within 2 minutes with anti
-
A and anti
-
B serum a
nd within 5 minutes with
anti
-
Rh serum. The results in the AB0 system are diagnosed by the following table (table
2). The Rh blood group is determined as follows. If the anti
-
Rh serum agglutinates
erythrocytes, the individual has Rh
+

blood. When no aggluti
nation with anti
-
R
h serum
occurs, the blood is Rh
-
.


Serum


anti
-
A

anti
-
B

Blood group

+

-

A

-

+

B

+

+

AB

-

-

0


Table 2.

Blood typing in the AB0 series using anti
-
A and anti
-
B sera: (+) agglutination, (
-
) no agglutination

P R A C T I C A L T R A I N I N G I
N P H Y S I O L O G Y

O F B L O O D

9

5.

Describe reactions with anti
-
A, anti
-
B, and anti
-
Rh agglutinins and determine your blood
group in AB0 and Rh systems.


Results:




Conclusion:




8.

CROSS
-

MATCHING OF BLOOD



Before transfusion, it is advisable to test directly the donor’s cells against the recipient’s
serum, and the
recipient’s cells against the donor’s serum, a procedure known as cross
-
matching.
This is a precaution not only against errors in grouping, but also tests for the presence of other
agglutinins, which may occasionally be present.


Materials:



Test tubes



Pipe
ttes



Pasteur’s pipette



Recipient’s and donor’s blood (HIV and HBsAg negative)



Centrifuge



Microscope slides and cover glasses



Microscope



Physiological solution of NaCl


Procedures:

1.

Remove plasmas recipient’s and donor’s bloods with Pasteur’s pipettes into t
he tubes
marked RPl (recipient’s plasma) and DPl (donor’s plasma).

2.

Prepare suspensions of red corpuscles. The suspensions must be prepared from cells that
had been washed. Add physiological saline solution to blood cells and centrifuge for 5
minutes at 5 0
00 r.p.m. Pipette off the supernatant fluid and use erythrocyte sediment for
the preparation of a 2 % suspension. Place 0.1 ml of washed donor’s erythrocytes to the
tube ErDP and 0.1 ml of washed recipient’s erythrocytes to the tube ErRP. Add 4.9 ml of
phy
siological saline to both test tubes.

3.

Turn the suspensions a few times upside down closing the mouth of the test tube with your
thumb.

4.

Prepare colloid erythrocyte suspension mixing one drop of blood cells with 1.0 ml of
corresponding plasma in test tubes E
rRC and ErDC. It is important not to have the
colloid suspension too thick.

5.

Make cross
-

matching by mixing equivalent volumes (0.1 ml) of ingredients as shown in
the table3:

6.

After 10 minutes incubation centrifuge the test tubes for one minute at 1 000 r.
p.m.

7.

Make readings of agglutination with the naked eye and by means of a low power objective
of the microscope. When no agglutination in any test tube occurs, the donor’s and
recipient’s bloods are compatible and the donor’s blood may be used for transfusi
on.

P R A C T I C A L T R A I N I N G I
N P H Y S I O L O G Y

O F B L O O D

1 0


donor’s plasma DPl

recipient’s plasma RPl

recipient’s erythrocyte suspension

in physiologic solution of NaCl (ErRP)

DPl+ErRP

--------------------------

colloid recipient’s erythrocyte suspension

(ErRC)

DPl+ErRC

--------------------------

suspension

of donor’s erythrocytes

in physiologic solution of NaCl (ErDP)

-----------------------

RPl+ErDP

colloid donor’s erythrocyte suspension

(ErDC)

-----------------------

RPl+ErDC


Table 3.




Results:







Conclusion: