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Practical work #13. Definition of capillary resistance
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Practical work #13. Definition of capillary resistance

Vessel-thrombocytory haemostasis is the first stage of blood clotting. With the help of this process small vessel injuries can be liquidated in short period of time. Thrombocytes constantly control capillaries permeability. Method that is described allows defining if thrombocytes perform their protective function when blood pressure is increased. The degree of capillary protection depends on the characteristics of capillary endothelium and the number of thrombocytes in blood.

Objectives: to estimate capillaries resistance to the increase of blood pressure.

Requirements for work: Rive-Rochi apparatus, clock.

draw a circle with diameter 5 cm on the skin of the internal surface of the forearm.

put the cuff from the manometer on the arm and make the pressure in it 12 – 13,3 kPa (90 – 100 mmHg).

hold the pressure in the cuff for 5 minutes.

wait till the blood circulation in the hand would be restored. Count the number of petechiae (small hemorrhages) on the marked surfaces. Pay attention to the diameters of the petechiae.

normally the number of petechiae should not be more than 10 and diameter of it – 1 mm. In case of weak positive reaction – 20-30, strong positive – more than 30 petechiae

Recommendations for writing down the results:

Write down the number and diameters of petechiae.

Answer following questions in conclusion:

Is the capillary resistance of the patient normal?



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