A semi-automated device rapidly determine circulating blood volume in healthy males and carbon monoxide uptake kinetics of arterial and venous blood

Validation of a clinically applicable device for fast and accurate quantification of blood volume

“…The semi-automated device has been reported to quantify changes in total hemoglobin mass and BV within a margin of 50 g and 200 mL, respectively, when measured immediately after a 900 mL whole blood donation although with individual differences. 20 In contrast to these previous findings, we here demonstrate that the semiautomated device displays a very low CV% and thus precisely can measure even clinically irrelevant (i.e., 2%) reductions in BV with little individual variation (Table 2) as previously shown using a manual CO-rebreathing approach, 23 emphasizing its potential use in contexts requiring a high degree of accuracy. When the dual-isotope infusion technique was consented being state-of-the-art in 1980, the development of blood gas analyzers and spectrophotometers was at its infancy, while they today are present in most clinical settings world-wide, thus allowing for an easy, precise, and accurate measurement of HbCO%.…”

“…With CO rebreathing, accuracy is routinely quantified by removing a known volume of blood between two measurements and then establish whether the actual removed volume could be detected. Both precision and accuracy are reported well within clinically relevant limits 10,12,19–21 …”

“…However, whether this is the case or is of any measurable relevance is unclear. In summary, independent of the methodological differences both the manual and semi‐automated version of the CO‐rebreathing method has been proven accurate and precise 10,12,20–22 …”

“…An unfortunate limitation with the dual‐isotope approach is that it is difficult to adequately validate in humans due to the long half‐life of the radioactive tracers (8–14 days) as well as the risks associated with repeated exposure to radioactivity. Both contrast with CO rebreathing where reproducibility is routinely addressed in studies investigating various interventions aimed at changing BV 1,20,23,25,26,34,36–39 . Here, we took the opportunity to determine intravascular volumes twice interspersed by ~4 weeks with both methods in two subjects (Table S2).…”

“…Both precision and accuracy are reported well within clinically relevant limits. 10,12,[19][20][21] Within the last two decades different rebreathing protocols have emerged (e.g., 2, 6, and 10-min of rebreathing), but only the 10-min laboratory protocol has been compared directly to the dual-isotope procedure and where a nearly perfect correlation (r 2 = 0.94) was reported and the absolute measurements of BV differed by just ~50 mL. 22 Realizing the limitations of not being able to perform repeated measurements with the dual-isotope methodology within a short timeframe, we investigated the correlation between 2 and 10-min CO-rebreathing protocols to values obtained from the dual-isotope technique.…”