Estimating blood volume in obese and morbidly obese patients

Preoperative assessment of blood volume (BV) is important for patients undergoing surgery. The mean value for indexed blood volume (InBV) in normal weight adults is 70 mL/kg. Since InBV decreases in a non-linear manner with increasing weight, this value cannot be used for obese and morbidly obese patients. We present an equation that allows estimation of InBV over the entire range of body weights.