Taking less blood for intensive care tests reduces the risk of transfusions, which can cause allergic reactions or infections
By Carissa Wong
12 October 2023
Standard blood collection tubes withdraw up to 6 millilitres of blood for tests in intensive care
Pirke/Shutterstock
Using smaller vials to collect blood samples from people in intensive care could help to prevent risky transfusions. The simple change could lower the risk of complications and preserve valuable supplies of donated blood.
Most hospitals around the world use standard blood collection tubes, which withdraw 4 to 6 millilitres of blood, when carrying out tests on people in intensive care units (ICUs). But most of these tests – which check organ function, clotting and respiratory health – require less than 0.5 millilitres of blood.
With multiple blood samples often being taken from people in ICUs every day, unnecessarily large samples can lead to substantial blood loss and anaemia.
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“After eight days in intensive care, the amount of blood loss is equivalent to donating a unit of whole blood [around 350 to 525 millilitres],” says Deborah Siegal at the University of Ottawa in Canada. “Unlike healthy blood donors, ICU patients are [often] unable to produce more red blood cells to correct for this blood loss.”
Roughly 40 per cent of people in intensive care need blood transfusions, often due to their illness or injuries. Taking unnecessarily large blood samples on top of this adds to the need, says Siegal.