Physiology Laboratory Packed Cell Volume 2021-2022 PDF
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Thi Qar University
2022
Dr Hadi Al-Sagur
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Summary
This document is a laboratory practical or lecture about packed cell volume (PCV) and hematocrit values, which are important for understanding blood components and functions. It covers various aspects like equipment, normal values, and factors affecting PCV. The document is part of a physiology laboratory course likely within a medical program offered in Iraq.
Full Transcript
Dr Hawraa Jafaar The haematocrit (PCV) is the percent of the packed red cells in a volume of whole blood. It is a screening test for anaemia or polycythemia. Volume of RBCs ∕ unit volume of whole blood i.e. percentage of packed cells to the whole blood. Haematocrit is the ratio of the height of re...
Dr Hawraa Jafaar The haematocrit (PCV) is the percent of the packed red cells in a volume of whole blood. It is a screening test for anaemia or polycythemia. Volume of RBCs ∕ unit volume of whole blood i.e. percentage of packed cells to the whole blood. Haematocrit is the ratio of the height of red cells column to that of the whole blood in the tube. The two methods of direct measurement of the PCV which are in current use are: 1. Macro-method using Wintrobe tubes. 2. Micro-method using capillary tubes. Normal value: for ♂ (40% -54%) ≈ 47% ♀ (36% - 47%) ≈ 42% Factors affecting PCV Number of RBC Shape of RBC (sickle cell) Plasma volume Aim of the experiment PCV↑↑ in polycythemia & dehydration. PCV↓↓ in anemia. The color of plasma may give an indication about some illness, red (hemolysis), yellow (jaundice). Instruments Special tubes → wintrobe hematocrit tube or Capillary tube Sample of blood + anti coagulant. Centrifuge the tube for 30 mint at 3000rev./min. (Micro-haematocrite centrifuge). - Plastic sealer The blood separated into 3 layers: Top layer (plasma) clear. Middle thin layer Buffy coat less than 1mm in thickness (WBCs & platelets). Dark red color bottom layer (RBCs). 5 liter in adult 45% is packed cells volume (PCV) 55% is plasma volume Thank you Physiology Laboratory Dr Hadi Al-Sagur Haematocrit or PCV Introduction The term hematocrit (or haematocrit in British English) comes from the Ancient Greek words haima (αἷμα, "blood") and kritēs (κριτής, "judge"), and hematocrit means "to separate blood". Hematocrit (HCT) For example, a hematocrit of 25% means that there are 25 milliliters of red blood cells in 100 milliliters of blood. 2 Haematocrit or PCV The normal ranges for hematocrit are depended on the age and, after adolescence, the sex of the individual. The normal ranges are: Age Hematocrit Ranges Newborn 55% to 68% One (1) week of age 47% to 65% One (1) month of age 37% to 49% Three (3) months of age 30% to 36% One (1) year of age 29% to 41% Ten (10) years of age 36% to 40% Adult males 42% to 54% Adult women 38% to 46% 3 Haematocrit or PCV Principles of centrifugation A centrifuge is used to separate particles suspended in a liquid according to particle size and density, viscosity of the medium, and rotor speed. 4 Haematocrit or PCV Capillary A Capillary tube with internal diameter of 1mm and length 75mm. Leave the last 15mm unfilled. 5 Haematocrit or PCV Lancet 6 Haematocrit or PCV Clay 7 Haematocrit or PCV Microcentrifuge 8 Haematocrit or PCV PCV reader 9 Haematocrit or PCV 10 Haematocrit or PCV Equipment: Anticoagulated whole blood (normally in EDTA*) Clay sealer PCV reader (card or Hawksley model) Centrifuge Capillary tubes Disposable gloves Tissue paper Sharps container Clinical waste bin Refuse bin * EDTA (Ethylenediaminetetraacetic acid) which prevents blood clotting 11 Thank you 12 Questions 13
