The Minimum discard volume: Accurate analysis of peripheral hematocrit

Document Type



The purpose of this research is to quantify the minimum amount of blood that must be discarded from an indwelling peripheral intravenous catheter (deadspace 0.5 ml) to obtain an accurate hematocrit reading. Repeat blood sampling from nine subjects is used to develop a mathematical model (Michaelis-Menten curve) describing the mixing of the flush solution and the blood. This model is used to estimate the hematocrit when different volumes are discarded. Differences between the computed hematocrit and true hematocrit were determined for each subject. When 1.5 ml (three times the deadspace volume) is discarded, the 95% confidence interval is within 0.6% of the true hematocrit.


Blood — Analysis; Hematocrit – Measurement; Intravenous therapy; Phlebotomy – Research


Hematology | Nursing


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