A significant study suggests that by reducing the volume of blood collected for laboratory tests, intensive care units (ICUs) can lessen the frequency of transfusions required for critically ill patients. Often, these patients require multiple blood draws per day, a procedure that can have considerable impacts on individuals in a fragile state.
Approximately 90% of the blood collected in a standard test tube—which is capable of drawing up to six millilitres—is unnecessarily discarded as a typical lab test requires only 0.5 ml of blood. This realization led researchers to assess whether standard and lower-volume tubes produced different outcomes for 27,000 patients across 25 intensive care units in Quebec, Ontario, New Brunswick, and Manitoba from 2019 to 2021. However, the data was adjusted to exclude a five-month hiatus induced by the pandemic.
The research, recently published in the Journal of the American Medical Association, concluded that tubes collecting roughly half the volume of standard tubes adequately supplied the necessary amount for typical laboratory tests. More impressively, the reduction facilitated a drop in transfusion volume, sparing one transfusion for every 10 ICU patients.
These smaller tubes are identical in design to their standard counterparts, only containing less anticoagulant, a substance to prevent clotting, thus permitting smaller blood draws. Hematologist Dr. Deborah Siegal of The Ottawa Hospital explains that the standard tubes cannot be partially filled due to the proportion of anticoagulant present: a reduction in the blood collected would interfere with the clotting process.
It’s concerning to note that around 40% of the most severely unwell patients endure multiple laboratory tests, leading to considerable blood loss which contributes to anemia. Smaller-volume tubes, that are already commonly used with children, help in mitigating these effects.
According to Dr. Siegal, the implementation of smaller tubes into ICU practice was straightforward, with hospital staff simply replacing the existing standard tubes in storage areas. This switch was integrated into patient care routines by the very individuals tending the patients, ensuring a smooth transition.
Dr. Siegal encourages a shift in protocols across ICUs worldwide considering the success of the study. She emphasizes the issue of excessive blood draws leading to unnecessary transfusions, while the blood could be used for surgeries or cancer treatments, where it is most critical.
Moreover, the patients involved in the study required more than 36,000 blood transfusions during their time in ICUs. The adoption of smaller tubes may have conserved around 1,500 units of blood, with one unit of blood equating to half a litre.
Critiques surrounding the use of standard tubes to draw blood from critically ill ICU patients are not new, having been derogatively named “ICU vampirism” by Mayo Clinic researchers in 2010. They similarly advised the adoption of more restrictive blood draw policies at hospitals.
This study and the positive outcomes it cultivates are a strong endorsement to implementing the use of smaller-volume tubes universally as a standard of care. Healthcare professionals should both reduce the harm caused to patients with excessive blood draws and treat the blood as the precious resource it is. In essence, conserving supplies and, most importantly, saving lives.
