Influence of lipid emulsion for the hematocrit value measured with continuous hematocrit monitor

Continuous monitoring of hematocrit with a CRIT-LINE monitor (CLM) is used to prevent excess ultrafiltration during hemodialysis and continuous renal replacement therapy. The presence of substances affecting the scattering and absorption rates of multiple wavelengths of near infrared rays of CLM in the blood may affect the measured values with CLM. We examined the influences of lipid emulsion (LE) on hematocrit and relative blood volume (RBV) which were measured with CLM using an in vitro experimental model with human blood. Additions of 10% or 20% of LE increased the hematocrit measured by LCM and decreased the percent change of RBV in proportion to the dose. One percentage of 20% LE in the plasma increased the expected hematocrit measured with CLM by 2.9%. The decrease of initial hematocrit from 48.1% to 43.4% decreased the expected percent change of RBV from -3.4% to -3.7% with the addition of 1 ml of 20% LE to 100 ml blood. These findings indicate that additions of LE increase hematocrit that is measured with CLM in proportion to the dose of LE. Low levels of initial hematocrit will increase the degree of expected percent change of RBV. Attention should be paid to the influence of LE during monitoring with CLM.