Total hemoglobin mass (Hb_mass) is routinely assessed in studies by the carbon monoxide (CO) rebreathing. Its clinical application is often hindered due to the consequent rise in carboxyhemoglobin (%HbCO) and the concern of CO toxicity. We tested the reproducibility of the CO rebreathing with a CO dose of 0.5 mL/kg body mass (CO_0.5) compared to 1.5 mL/kg (CO_1.5) and when shortening the CO rebreathing protocol. Therefore, CO rebreathing was performed 1×/day in eight healthy individuals on four consecutive days. On each day, either CO_0.5 (CO_0.5-1 and CO_0.5-2) or CO_1.5 (CO_1.5-1 and CO_1.5-2) was administered. Venous blood samples to determine %HbCO and quantify Hb_mass were obtained prior to, and at 6 (T₆), 8 (T₈) and 10 min (T₁₀) of CO rebreathing. This protocol was tested at sea level and at 2320 m to investigate the altitude-related measurement error. At sea level, the mean difference (95% limits of agreement) in Hb_mass between CO_0.5-1 and CO_0.5-2 was 26 g (–26; 79 g) and between CO_1.5-1 and CO_1.5-2, it was 17 g (–18; 52 g)_. The respective typical error (TE) corresponded to 2.4% (CO_0.5) and 1.5% (CO_1.5), while it was 6.5% and 3.0% at 2320 m. With CO_0.5, shortening the CO rebreathing resulted in a TE for Hb_mass of 4.4% (T₈ vs. T₁₀) and 14.1% (T₆ vs T₁₀) and with CO_1.5, TE was 1.6% and 5.8%. In conclusion, the CO dose and rebreathing time for the CO rebreathing procedure can be decreased at the cost of a measurement error ranging from 1.5-14.1%.

在研究中，通常通过一氧化碳（CO）呼吸来评估总血红蛋白质量（Hb _mass）。由于羧基血红蛋白（％HbCO）的增加以及对CO毒性的关注，其临床应用常常受到阻碍。我们以0.5 mL / kg体重（CO _0.5）与1.5 mL / kg（CO _1.5）的CO剂量测试了CO再呼吸的重现性，并缩短了CO再呼吸方案。因此，连续四天在八名健康个体中每天进行1次CO呼吸。每天使用CO _0.5（CO _0.5 -1和CO _0.5 -2）或CO _1.5（CO _1.5 -1和CO _1.5-2）。在CO呼吸之前和6（T ₆），8（T ₈）和10 min（T ₁₀）之前和之后获得静脉血样以确定％HbCO并量化Hb_质量。在海平面和2320 m处对该协议进行了测试，以调查与海拔相关的测量误差。在海平面上，CO _0.5 -1和CO _0.5 -2之间的Hb_质量平均差异（一致限的95％）为26 g（–26; 79 g），CO _1.5 -1和CO _1.5 -2之间的平均差异为是17克（–18; 52克）_。各自的典型误差（TE）分别对应于2.4％（CO _0.5）和1.5％（CO _1.5），而在2320 m处分别为6.5％和3.0％。使用CO _0.5时，缩短CO再呼吸会导致Hb_质量的TE分别为4.4％（T ₈对T ₁₀）和14.1％（T ₆对T ₁₀），而CO _1.5时，TE分别为1.6％和5.8％。总之，可以以1.5-14.1％的测量误差为代价，减少用于CO再呼吸程序的CO剂量和再呼吸时间。