When do benefits turn to risks? Impact of a 900 mL whole blood donation on Special Forces performance

Background: Special Forces (SF) teams operate in remote environments with limited medical support. As a result, they may need to rely on buddy transfusions to treat bleeding teammates. Considering that 450 mL has no direct impact on their combat performances, it might be tempting to take more blood from a compatible donor to save a hemorrhaging teammate. This study investigates the effect of a 900 mL blood donation on SF operator performance and recovery time following this donation.

Study design and methods: Participants underwent a multifactorial assessment including measures of physiological parameters, vigilance, and physical performance. Results from the day of blood donation were compared with baseline values obtained 1 week earlier (i.e., immediate effect), as well as repeated testing at 7, 14, and approximately 30 days after blood donation (i.e., recovery period).

Results: Hemoglobin levels and heart rate were affected by giving blood. The participants also experienced a significant decrease in physical performance of more than 50% immediately after blood donation. Recovery was slow over the following weeks, remaining significantly different from baseline until full recovery around day 30. However, participants were still able to respond to a simple stimulus and adjust their response, if necessary, even immediately after donating blood.

Discussion: A 900 mL blood donation greatly affects the physical fitness of SF operators. A donation may be worthwhile if it is the only life-saving procedure available and does not endanger the donor's life. The donor would then become a patient and unable to complete the mission.