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Blood Collection
Blood Collection

Prolonged Tourniquet Application

February 15th, 2021


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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