Download MBBS Practicals Physiology PCV Estimation

Download MBBS (Bachelor of Medicine and Bachelor of Surgery) Practicals Latest Physiology PCV Estimation

Determination Of Packed Cell
Volume by Macro Method

Clinical Importance of PVC
Aim of Presentation

To Know

? What is Packed Cell Volume (PCV)
? Methods for Determination of PCV (Hematocrit)
? Clinical Importance of PCV (Hematocrit)
PCV

? PCV also known as Hematocrit is the volume

occupied by Erythrocytes in the given volume
of

blood

and

is

usually

expressed

as

percentage of the volume of the whole blood
sample.

Hematocrit (PCV)

? Hematocrit is derived from Greek words `Haima'

meaning blood `krites' meaning to Separate. Together

Hematocrit means `to separate blood'



PRINCIPLE

? Anticoagulant mixed blood is filled in a tube and

centrifuged.Cells settle down towards the bottom
because of their greater density leaving the clear
plasma on upper side



PROCEDURE

? Under aseptic condition get a venous blood sample.

? Carefully mix the blood with anticoagulant (Ammonium oxalate 3mg

and Potassium Oxalate 2mg) in a tube by repeated inversions.

? Fill the Wintrobe tube with the help of Pasteur pipette to the 10cm

mark. Which represents 100%.

? Place the Wintrobe tube in the centrifuge machine and other Wintrobe

tube filled with water on the opposite side so as to balance it.



Precautions

? There should be no air bubble or froth of blood in the tube.

? Always use double oxalate as anticoagulant.

? Wintrobe tube should be clean and dry.




True hematocrit

? After centrifugation small amount of plasma is still entrapped between

RBCs.So the true Hematocrit is calculated as:

? Hematocrit

96

True Hematocrit

100
Buffy Layer

? The buffy layer consists of packed platelets and leukocytes

? Thickness 1mm

? The thickness of buffy layer increases in leucocytosis ,leukaemia and

thrombocytosis
Clinical Importance


Physiologic (Normal) increase in PCV

? New born and Infants
? High altitude
? Higher in man as compared to female
Physiologic (Normal) decrease in PCV

? Less in women as compared to man

? Pregnancy ( hemodilution)