Study finds withdrawing less blood for ICU lab tests reduces patient strain, waste

Intensive care units can collect less blood for lab tests and thereby reduce transfusions for critically ill patients who may have blood drawn multiple times a day, suggests a large study that says switching to lower-volume tubes can preserve the blood supply and reduce strain on already fragile patients.

Intensive care units can collect less blood for lab tests and thereby reduce transfusions for critically ill patients who may have blood drawn multiple times a day, suggests a large study that says switching to lower-volume tubes can preserve the blood supply and reduce strain on already fragile patients.

Researchers note that 90 per cent of blood collected by a standard test tube -- which can draw up to six millilitres -- is wasted because only 0.5 ml of blood is needed for a typical lab test.

They compared the use of regular and lower-volumetubes for tests involving 27,000 patients at 25 intensive care units in Quebec, Ontario, New Brunswick and Manitoba between 2019 and 2021, minus a five-month delay during the pandemic.

The study, published Thursday in the Journal of the American Medical Association (JAMA), found that using a tube that collects about half the amount provides more than enough blood for a typical lab test. The switch also saved one blood transfusion for every 10 patients in ICUs.

The alternate tubes are physically identical to standard tubes but allow for a smaller draw because they contain less anticoagulants, which prevent blood from clotting, said lead author and hematologist Dr. Deborah Siegal of The Ottawa Hospital.

She said it's one of the reasons standard tubes can't be partly filled. Lower-volume tubes also generate a weaker vacuum pullso automatically draw less blood, she added.

Siegal said about 40 per cent of the sickest patients have repeated lab tests, resulting in significant blood loss thatcontributes to anemia, or low red blood cells. That leads to more blood transfusions.