Tourniquet use and its effect on different lab parameters Cause of hemolysis and effect on lab parameters.

1. TOURNIQUET USE AND ITS EFFECT
ON DIFFERENT LAB PARAMETERS
Raghwendra Sah
Bsc.MLT 4th year(2016 batch)
Gandaki Medical College,
Lekhnath, Kaski

2. Introduction
• A tourniquet is a device which applies pressure to a limb or extremity
in order to limit – but not stop – the flow of blood.
• Tourniquet is widely used for venipuncture by medical and laboratory
staff but very few are aware of effect of tourniquet application on
laboratory parameters.
• Venous blood sampling is usually performed using a tourniquet to
help locate and define peripheral veins to achieve successful and safe
venipuncture.
• Tourniquet application should be minimized because it causes
spurious and significant variation of several plasma analytes.

3. TOURNIQUET USE
• Locate and define peripheral veins to achieve successful and safe
venipuncture.
• Partially delay venous blood flow back toward the heart and
cause the blood to temporarily pool in the vein.

4. TOURNIQUET EFFECT
• Tourniquet application less than 1 minute doesn’t produce
significant effect on different lab parameters.
• Prolonged tourniquet application actually deviates result tested
from actual result by following ways:-
Local hypoxia and thus acidosis, which can affect potassium measurement.
Venous stasis facilitates the exit of water and diffusible ions from the
vessels.
Local tissue damage; stimulation of calcium relase and clotting factor.

5. TOURNIQUET EFFECT on basis of lab parameters
Increase Decrease
GLUCOSE,POTASSIUM,CALCIUM,
PROTEIN, ALBUMIN AND
CHOLESTEROL
SODIUM AND CHLORIDE

6. CAUSE OF HEMOLYSIS AND ITS EFFECT
IN DIFFERENT LAB PARAMETERS

7. Introduction
• Hemolysis is process characterized by accelerated breakdown of the
erythrocyte (RBC) membranes, releasing intra-erythrocyte content to
the extracellular compartment .
• In this process not only hemoglobin is released, other components of
the erythrocyte cytoplasm such as potassium, lactate dehydrogenase
(LDH), or neuro-specific enolase (NSE) among other components.
• Hemolysis represents an important source of error associated with
the pre-analytical phase.

8. CAUSES OF HEMOLYSIS
• Hemolysis can be due either to pathophysiological reasons or to causes
exogenous to the patient.
• Hemolysis can be classified into two large blocks:
In vivo hemolysis: characterized by the breakdown of RBCs due to
endogenous causes, inside the blood vessel.
In vitro hemolysis: characterized by the rupture of the RBCs is due
to improper blood collection or sample handling .This kind of
hemolysis may be due to phlebotomist using too thin needle size,
inappropriate tubes mixing, or a too prolonged tourniquet time , as
well as due to causes related to the transport or storage of the
samples

11. EFFECT OF HEMOLYSIS ON DIFFERENT LAB
PARAMETERS
• Potassium, LDH, AST, magnesium ,phosphorus ,bilirubin ,creatinine
kinase, lipase, albumin and g-glutamyl transferase get overestimated.
• Alkaline phosphatase , sodium, chloride and glucose get
underestimated.
• The interference degree caused by hemolysis is not only important in
spectrophotometric biochemical tests, but also in gasometric,
hematocytometric, coagulometric and immunoassay tests.