Indirect Measurement of Red Cell Volume

Abstract

Anemia is a commonly observed problem in the intensive care unit (ICU). Hematocrit (Hct) or hemoglobin levels have been used empirically to decide when to transfuse erythrocytes despite the fact that single Hct or hemoglobin measurements may not be reliable for this purpose in ICU patients (Marino 1997). Measurement of red cell volume (RCV) would help provide more reliable information for transfusion purposes because volume loading or fluid restriction is commonly performed in the ICU. However RCV indicators, even those using a nonradioactive tracer such as sodium fluorescein, generally require labeling of the patient’s erythrocytes, blood sampling, and subsequent measurement of blood tracer concentration (Orth et al. 1998).