Swolinsky JS, Tuvshinbat E, Leistner DM, et al. - In acute heart failure (AHF) cases, hemoglobin (Hb) or hematocrit (Hct) alterations did not reflect directly measured alterations of intravascular volume status. On an individual patient level, clinical decision-making could be misguided if clinical evaluation of decongestion is based on changes of Hb or Hct.

• In 36 AHF patients receiving diuretic therapy, two sequential assessments of measured plasma volume (mPV), measured red cell volume (mRCV) and measured total blood volume (mTBV) (48 h apart) were made.

• Patients showed a wide range of alterations of mPV (−25.4% to +37.0%).

• The mPV alterations did not significantly correlate with changes of Hb level, Hct, estimated plasma volume (ePV _{Kaplan–Hakim} ), or ePV _Strauss .

• Alterations of mTBV showed poor correlation with changes of Hb levels, and some cases demonstrated unanticipated variability of mRCV, indicating an unstable intravascular red cell pool.