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A randomized controlled pilot study of VO 2 max testing: a potential model for measuring relative in vivo efficacy of different red blood cell products
Author(s) -
BennettGuerrero Elliott,
Lockhart Evelyn L.,
Bandarenko Nicholas,
Campbell Mary L.,
Natoli Michael J.,
Jamnik Veronika K.,
Carter Timothy R.,
Moon Richard E.
Publication year - 2017
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1111/trf.13918
Subject(s) - medicine , apheresis , randomized controlled trial , red blood cell , cycle ergometer , confounding , randomization , surgery , physical therapy , blood pressure , heart rate , platelet
BACKGROUND Randomized trials, for example, RECESS, comparing “young” (median, 7‐day) versus “middle‐aged” (median, 28‐day) red blood cells (RBCs), showed no difference in outcome. These data are important; however, they do not inform us about the safety and effectiveness of the oldest RBCs, which some patients receive. It may not be feasible to conduct a clinical trial randomizing patients to receive the oldest blood. Therefore, we propose strenuous exercise (VO 2 max testing) as a model to study the relative efficacy to increase oxygen delivery to tissue of different RBC products, for example, extremes of storage duration. STUDY DESIGN AND METHODS In this pilot study, eight healthy subjects had 2 units of leukoreduced RBCs collected by apheresis in AS‐3 using standard methods. Subjects were randomized to receive both (2) units of their autologous RBCs at either 7 or 42 days after blood collection. VO 2 max testing on a cycle ergometer was performed 2 days before (Monday) and 2 days after (Friday) the transfusion visit (Wednesday). This design avoids confounding effects on intravascular volume from the 2‐unit blood transfusion. The primary outcome was the difference in VO 2 max between Friday and Monday (delta VO 2 max). RESULTS VO 2 max increased more in the 7‐day RBC arm (8.7 ± 6.9% vs. 1.9 ± 6.5%, p = 0.202 for comparison between arms). Exercise duration (seconds) increased in the 7‐day RBC arm (8.4 ± 1.7%) but actually decreased in the 42‐day arm (−2.6 ± 3.6%, p = 0.002). CONCLUSIONS This pilot study suggests that VO 2 max testing has potential as a rigorous and quantitative in vivo functional assay of RBC function. Our preliminary results suggest that 42‐day RBCs are inferior to 7‐day RBCs at delivering oxygen to tissues.