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Blood Collection

Prolonged Tourniquet Application



  • Tourniquets are a very useful tool for identifying veins when taking blood or inserting a cannula. However, leaving a tourniquet on for too long can affect the interpretation of blood test results.
  • Ideally the tourniquet should be left on for no longer than a minute at a time - if you are having difficulty finding a vein, then release the tourniquet, wait for blood flow to return, then reapply the tourniquet.
  • Always remember to release the tourniquet when leaving a patient's bedside, as very prolonged tourniquet application can result in significant complications.
    • Effects of Prolonged Tourniquet Application

    • On Blood Results

    • Haemoconcentration - water and certain solutes extravasate into the extracellular space, resulting in falsely elevated results
    • Elevated lactate
    • Elevated total protein, AST, lipids, cholesterol and iron
    • On the Patient

    • Bruising
    • Nerve palsies - numbness, paraesthesias or weakness
    • Limb ischaemia
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