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TOPIC 13 HEMATOCRIT AND ITS SIGNIFICANT.pptx

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Hematocrit, also known as packed cell volume, is the percentage of red blood cells in blood. It is an important indicator in a complete blood count. The normal ranges are 46% for males and 38% for females. Hematocrit can be measured through microhematocrit and macrohematocrit methods. Microhematocrit involves centrifuging a blood sample in a capillary tube and reading the percentage of red blood cells. Macrohematocrit uses a Wintrobe tube and centrifugation to separate plasma from red blood cells to determine the hematocrit percentage. Precise measurement requires avoiding errors like not including the buffy coat layer or improper sealing of tubes.

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TOPIC 13 HEMATOCRIT AND ITS SIGNIFICANT
HEMATOCRIT (HCT) •Hematocrit is defined The percentage by volume of packed red blood cells in a given sample of blood after centrifugation. • The hematocrit may also be referred to as Packed Cell Volume (PCV) or erythrocyte volume fraction (EVF). •HCT is expressed as %
•Normal range: • Male: 46% • Female: 38% •It is considered an integral part of a person’s complete blood count result along with haemoglobin concentration, white blood cell count and platelet count.
INDICATION OF HCT ESTIMATION for detecting the presence and degree of anemia or polycythemia ( MOST ACCURATE AND SIMPLEST) For calculation of red cell indices
METHODS 1. Microhaematocrit 2. Macrohematocrit method (Wintrobe Method) 3. Automated cell counting
Results (both methods) The percentage of the volume of blood occupied by the red cells constitutes hematocrit or packed cell volume. Hct % = {Height of RBCs (mm) / Height of RBCs and plasma (mm)} × 100 For example, if the height of packed red cells is 45 mm, then = 45/ 100 × 100 = 45 percent. • It also means that out of 100 volumes (or parts) of blood 45 volumes (or parts) are red cells and 55 volumes (or parts) are plasma. Thus, out of 1 liter of blood, 450 ml are red cells and 550 ml are plasma.
CLINICAL SIGNIFICANCE
CLINICAL SIGNIFICANCE
MICROHEMATOCRIT
TOPIC 13 HEMATOCRIT AND ITS SIGNIFICANT.pptx
SAMPLE Whole blood using dipotassium EDTA as the anti-coagulant OR Free flowing capillary blood (use heparinized capillary tubes)
PRINCIPLE Blood specimen is centrifuged in a sealed capillary tube and Packed Cell Volume is determined by a special haematocrit reader and gives the result as percentage.
Material and instruments 1. Microhaematocrit tube (capillary tube) 75mm in length and 1mm in diameter which contains heparin and show a red ring at the end of the tube. 2. Microhaematocrit centrifuge device. 3. Plastic seal to seal one end of Microhaematocrit capillary tube. 4. Microhaematocrit reader.
Procedure: 1. Clean your finger with 70% alcohol and let dry. 2. Prick finger with lancet, near the tip but not too close to the nail. Prick so that blood flows freely. Try squeezing up from your wrist if blood does not flow after pricking finger. 3.Place the tip of a capillary tube onto a drop of blood on your finger. 4.Call your instructor to seal the tube. 5. The instructor will spin the tubes in a centrifuge ( 5 minutes at 10000 rpm),. 7. Using a special reading device(since the capilary tube is not graduated),
Observations and Results: Note that the blood has been separated into 3 layers: i. A tall upper layer of clear plasma—amber slightly yellow-colored. It should not be pink or red which would indicate hemolysis of red cells in the sample or within the body in hemolytic diseases. ii. A greyish-white, thin layer (about 1 mm thick) the so-called “buffy layer”, consisting of platelets (thrombocytes) above and leukocytes below it. iii. A tall bottom layer of red cells which have been closely packed together. A greyish red line separates red cell layer from the layer of leukocytes above it.
PRECAUTIONS! DO NOT INCLUDE BUFFY COAT WHEN READING RESULTS AVOID PARALLAX ERROR PARALLAX: defined as an object being seen in a different position by changing the position of the head, or as seen by one eye versus the other eye)
SOURCE OF ERROR 1. An increased amount of anti-coagulant decreases the Hct reading as a result of erythrocyte shrinking. 2. Improper sealing of the capillary tube causes a decreased Hct reading as a result of loss of blood during centrifugation. a higher number of erythrocytes are lost in relation to the plasma. 3. The microhematocrit centrifuge should never be forced to stop by applying pressure to the metal cover plate. This will cause the RBC layer to “sling” forward and results in a falsely elevated value.
SOURCE OF ERROR 4. The buffy coat of the specimen should not be included in the Hct reading, because its inclusion falsely elevates the result. 5. A decrease or increase in the readings may be seen if the microhematocrit reader is not used properly. 6. If too much time elapses between when the centrifuge stops and the capillary tube is removed, the red cells can begin to settle out and cause a false reading of the hematocrit.
MACROHEMATOCRIT METHOD (WINTROBE METHOD)
TOPIC 13 HEMATOCRIT AND ITS SIGNIFICANT.pptx
SAMPLE Double Oxalated or EDTA anticoagulated venous blood (the specimen need not be a fasting sample).
PRINCIPLE When anticoagulated blood is centrifuged in haematocrit tube at high speed, the erythrocytes sediment at the bottom and the sedimented red cell column is called packed cell volume (PCV) or hematocrit (cell percentage volume).
MATERIAL AND INSTRUMENTS 1.Wintrobe’s hematocrit tube. 2.Pasteur pipette. 3.Centrifuge machine.
PROCEDURE 1. Gently mixed the blood specimen and labeled the hematocrit tube. 2. Filled the blood into the Wintrobe’s hematocrit tube up to 100 mark by using a Pasteur pipette. (avoid formation of air bubbles into the tube). 3. Centrifuged the tube with balanced tube at 3000 RPM for 30 minutes or 3500 RPM for 15 minutes in the centrifuge machine. 4. Read the sedimented red cells layer and give the result as percentages (and multiply with 100 for volume percentages).
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TOPIC 13 HEMATOCRIT AND ITS SIGNIFICANT.pptx

  • 1. TOPIC 13 HEMATOCRIT AND ITS SIGNIFICANT
  • 2. HEMATOCRIT (HCT) •Hematocrit is defined The percentage by volume of packed red blood cells in a given sample of blood after centrifugation. • The hematocrit may also be referred to as Packed Cell Volume (PCV) or erythrocyte volume fraction (EVF). •HCT is expressed as %
  • 3. •Normal range: • Male: 46% • Female: 38% •It is considered an integral part of a person’s complete blood count result along with haemoglobin concentration, white blood cell count and platelet count.
  • 4. INDICATION OF HCT ESTIMATION for detecting the presence and degree of anemia or polycythemia ( MOST ACCURATE AND SIMPLEST) For calculation of red cell indices
  • 5. METHODS 1. Microhaematocrit 2. Macrohematocrit method (Wintrobe Method) 3. Automated cell counting
  • 6. Results (both methods) The percentage of the volume of blood occupied by the red cells constitutes hematocrit or packed cell volume. Hct % = {Height of RBCs (mm) / Height of RBCs and plasma (mm)} × 100 For example, if the height of packed red cells is 45 mm, then = 45/ 100 × 100 = 45 percent. • It also means that out of 100 volumes (or parts) of blood 45 volumes (or parts) are red cells and 55 volumes (or parts) are plasma. Thus, out of 1 liter of blood, 450 ml are red cells and 550 ml are plasma.
  • 11. SAMPLE Whole blood using dipotassium EDTA as the anti-coagulant OR Free flowing capillary blood (use heparinized capillary tubes)
  • 12. PRINCIPLE Blood specimen is centrifuged in a sealed capillary tube and Packed Cell Volume is determined by a special haematocrit reader and gives the result as percentage.
  • 13. Material and instruments 1. Microhaematocrit tube (capillary tube) 75mm in length and 1mm in diameter which contains heparin and show a red ring at the end of the tube. 2. Microhaematocrit centrifuge device. 3. Plastic seal to seal one end of Microhaematocrit capillary tube. 4. Microhaematocrit reader.
  • 14. Procedure: 1. Clean your finger with 70% alcohol and let dry. 2. Prick finger with lancet, near the tip but not too close to the nail. Prick so that blood flows freely. Try squeezing up from your wrist if blood does not flow after pricking finger. 3.Place the tip of a capillary tube onto a drop of blood on your finger. 4.Call your instructor to seal the tube. 5. The instructor will spin the tubes in a centrifuge ( 5 minutes at 10000 rpm),. 7. Using a special reading device(since the capilary tube is not graduated),
  • 15. Observations and Results: Note that the blood has been separated into 3 layers: i. A tall upper layer of clear plasma—amber slightly yellow-colored. It should not be pink or red which would indicate hemolysis of red cells in the sample or within the body in hemolytic diseases. ii. A greyish-white, thin layer (about 1 mm thick) the so-called “buffy layer”, consisting of platelets (thrombocytes) above and leukocytes below it. iii. A tall bottom layer of red cells which have been closely packed together. A greyish red line separates red cell layer from the layer of leukocytes above it.
  • 16. PRECAUTIONS! DO NOT INCLUDE BUFFY COAT WHEN READING RESULTS AVOID PARALLAX ERROR PARALLAX: defined as an object being seen in a different position by changing the position of the head, or as seen by one eye versus the other eye)
  • 17. SOURCE OF ERROR 1. An increased amount of anti-coagulant decreases the Hct reading as a result of erythrocyte shrinking. 2. Improper sealing of the capillary tube causes a decreased Hct reading as a result of loss of blood during centrifugation. a higher number of erythrocytes are lost in relation to the plasma. 3. The microhematocrit centrifuge should never be forced to stop by applying pressure to the metal cover plate. This will cause the RBC layer to “sling” forward and results in a falsely elevated value.
  • 18. SOURCE OF ERROR 4. The buffy coat of the specimen should not be included in the Hct reading, because its inclusion falsely elevates the result. 5. A decrease or increase in the readings may be seen if the microhematocrit reader is not used properly. 6. If too much time elapses between when the centrifuge stops and the capillary tube is removed, the red cells can begin to settle out and cause a false reading of the hematocrit.
  • 21. SAMPLE Double Oxalated or EDTA anticoagulated venous blood (the specimen need not be a fasting sample).
  • 22. PRINCIPLE When anticoagulated blood is centrifuged in haematocrit tube at high speed, the erythrocytes sediment at the bottom and the sedimented red cell column is called packed cell volume (PCV) or hematocrit (cell percentage volume).
  • 23. MATERIAL AND INSTRUMENTS 1.Wintrobe’s hematocrit tube. 2.Pasteur pipette. 3.Centrifuge machine.
  • 24. PROCEDURE 1. Gently mixed the blood specimen and labeled the hematocrit tube. 2. Filled the blood into the Wintrobe’s hematocrit tube up to 100 mark by using a Pasteur pipette. (avoid formation of air bubbles into the tube). 3. Centrifuged the tube with balanced tube at 3000 RPM for 30 minutes or 3500 RPM for 15 minutes in the centrifuge machine. 4. Read the sedimented red cells layer and give the result as percentages (and multiply with 100 for volume percentages).