TY - JOUR

T1 - The carbon monoxide re-breathing method can underestimate Hbmass due to incomplete blood mixing

AU - Keiser, Stefanie

AU - Siebenmann, Christoph

AU - Bonne, Thomas Christian

AU - Sørensen, Henrik

AU - Robach, Paul

AU - Lundby, Carsten

PY - 2013

Y1 - 2013

N2 - Purpose: Hemoglobin mass (Hbmass) is commonly assessed using the CO re-breathing method with the subject in the seated position. This may lead to an underestimation of Hbmass as blood in lower extremity veins while seated may not be tagged with carbon monoxide (CO) during the re-breathing period. Methods: To test this hypothesis, CO re-breathing was performed on four occasions in nine male subjects, twice in the seated position and twice in combination with light cycle ergometer exercise (1 W/kg body-weight) intending to accelerate blood circulation and thereby potentially allowing for a better distribution of CO throughout the circulation as compared to in the seated position. Blood samples were drawn from an antecubital vein and the saphenous magna vein following the re-breathing procedure. Results: In the seated position, CO re-breathing increased the percent carboxyhemoglobin (%HbCO) in the antecubital vein to 8.9 % (7.8-10.7) [median (min-max)], but less (P = 0.017) in the saphenous magna vein [7.8 % (5.0-9.9)]. With exercise, no differences in %HbCO were observed between sampling sites. As a result, CO re-breathing in combination with exercise revealed a ~3 % higher (P = 0.008) Hbmass, i.e., 936 g (757-1,018) as compared to 908 g (718-940) at seated rest. Conclusion: This study suggests an uneven distribution of CO in the circulation if the CO re-breathing procedure is performed at rest in the seated position and therefore can underestimate Hbmass.

AB - Purpose: Hemoglobin mass (Hbmass) is commonly assessed using the CO re-breathing method with the subject in the seated position. This may lead to an underestimation of Hbmass as blood in lower extremity veins while seated may not be tagged with carbon monoxide (CO) during the re-breathing period. Methods: To test this hypothesis, CO re-breathing was performed on four occasions in nine male subjects, twice in the seated position and twice in combination with light cycle ergometer exercise (1 W/kg body-weight) intending to accelerate blood circulation and thereby potentially allowing for a better distribution of CO throughout the circulation as compared to in the seated position. Blood samples were drawn from an antecubital vein and the saphenous magna vein following the re-breathing procedure. Results: In the seated position, CO re-breathing increased the percent carboxyhemoglobin (%HbCO) in the antecubital vein to 8.9 % (7.8-10.7) [median (min-max)], but less (P = 0.017) in the saphenous magna vein [7.8 % (5.0-9.9)]. With exercise, no differences in %HbCO were observed between sampling sites. As a result, CO re-breathing in combination with exercise revealed a ~3 % higher (P = 0.008) Hbmass, i.e., 936 g (757-1,018) as compared to 908 g (718-940) at seated rest. Conclusion: This study suggests an uneven distribution of CO in the circulation if the CO re-breathing procedure is performed at rest in the seated position and therefore can underestimate Hbmass.

KW - Blood volume

KW - CO

KW - nHb

KW - RCV

KW - Red cell mass

U2 - 10.1007/s00421-013-2681-0

DO - 10.1007/s00421-013-2681-0

M3 - Journal article

C2 - 23771574

AN - SCOPUS:84884812492

VL - 113

SP - 2425

EP - 2430

JO - European Journal of Applied Physiology

JF - European Journal of Applied Physiology

SN - 1439-6319

IS - 9

ER -