Reliability and validity of non‐invasive determined haemoglobin mass and blood volumes.

Summary: Introduction: The carbon monoxide (CO) rebreathing method used for the determination of haemoglobin mass (Hbmass) is associated with blood sample analysis (in this study: Radiometer ABL800). As an alternative hereto the aim of the present study was to evaluate the use of a portable and non‐invasive CO pulse oximeter (Rad‐57). Method: With simultaneous determination of CO in the circulation by ABL800 (%HbCO) and Rad‐57 (SpCO), Hbmass and blood volume (BV) were determined in duplicates in 24 volunteers. Percentage of typical errors (%TE) within methods and linear correlations between the two procedures were computed. Results: Hbmass (Rad‐57 = 798 ± 230 g; ABL800 = 781 ± 192 g) and BV (Rad‐57 = 5700 ± 1373 ml; ABL800 = 5581 ± 1096 ml) were similar between methods. However, the %TE for Hbmass was higher (<italic>P</italic><0·001) for Rad‐57 (5·84 ± 5·29%) than for ABL800 (1·35 ± 1·13%). Similarly, the %TE for BV was higher (<italic>P</italic><0·001) for Rad‐57 (6·06 ± 5·76%) than for ABL800 (1·48 ± 1·25%). Lower (<italic>P</italic><0·05) correlation coefficients between the methods were found when Hbmass > 905 g and BV > 6193 ml. Conclusion: Assessment of SpCO by Rad‐57 resulted in considerably less precise determinations of Hbmass and BV, especially for high values. Thus, non‐invasive assessment of Hbmass and BV cannot be recommended for scientific purposes, but may nonetheless be useful in clinical settings. [ABSTRACT FROM AUTHOR]