STRATUS will evaluate the use of small-volume ("soft-draw") blood collection tubes for laboratory testing in reducing anemia and transfusion in intensive care unit patients without significant adverse consequences. This is a simple, cost-neutral intervention that could improve the quality of patient care and reduce the harms of frequent laboratory testing.

Blood sampling can cause significant unnecessary blood loss particularly in the intensive care unit (ICU). Blood loss contributes to anemia which is highly prevalent in the ICU and is associated with major adverse cardiovascular outcomes and death. Red blood cell (RBC) transfusions to correct anemia also have significant health risks.

Using a stepped wedge cluster randomized trial design, the specific aim of the STRATUS study is to evaluate whether the routine use of small-volume blood collection tubes reduces RBC transfusion compared to standard-volume blood collection tubes in adult ICU patients.

ICUs will be eligible if they meet the following criteria:

1. Adult ICU
2. At least 14 level 2-3 ICU beds with capacity for invasive mechanical ventilation
3. Use of vacuum tubes for routine blood collection
4. Able to achieve at least 25% estimated reduction in blood volume by switching to small-volume vacuum tubes
5. Electronic administrative and health record data available for data collection