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

Introduction Determination of blood volume (BV) using the dual‐isotope (e.g., 99mTc‐labeled red blood cells [99mTc‐RBC] and 125I‐labeled human serum albumin [125I‐HSA]) injection method is limited in medicine due to the long isotope half‐life. However, BV has been determined in laboratory settings for 100 years using the carbon monoxide (CO)‐rebreathing‐based procedure, which allows frequent BV measurements. Methods We investigated the reliability and accuracy of a semi‐automated CO‐rebreathing device by comparing it against the dual‐isotope methodology and its ability to detect a known blood removal. In study A, BV was determined three times in ~2 h; twice using the device with rebreathing protocols lasting 2 (CO2min) and 10 min (CO10min) and once with the dual‐isotope technique. In study B, the accuracy of the device was assessed by its ability to detect a 2% removal of BV. Results A good correlation was observed between both the CO‐rebreathing protocols (r2 = 0.89–0.98; p