Performance of evacuated blood collection tubes at high altitude.

Researchers and clinicians may not be aware that the performance of evacuated blood collection systems is impaired at high altitude. We tested four sizes of Vacutainer tubes at altitudes ranging from sea level to 5341 m to and determined that draw volumes are reduced by approximately 0.5 mL for every 1000 m gain in terrestrial elevation. Insufficient blood volume can limit possibilities for testing, inappropriate blood to additive ratios can skew test results and with smaller tubes at higher altitudes there is a possibility of air embolism. With foresight and proper planning, these problems can be avoided, and evacuated blood collection tubes can still be used safely and effectively at high altitude.