How much blood should be wasted from a intravenous (IV) catheter before obtaining a blood sample?


Intravenous literature: Baker, R.B., Summer, S.S., Lawrence, M., Shova, A., McGraw, C.A. and Khoury, J. (2013) Determining Optimal Waste Volume From an Intravenous Catheter. Journal of Infusion Nursing. 36(2), p.92–96.


Waste is blood drawn from an intravenous (IV) catheter to remove saline or heparin before obtaining a blood sample. This study examines the minimum waste volume resulting in an undiluted sample. A repeated-measures design was used. Investigators placed an IV catheter in 60 healthy adults and obtained samples at baseline and following waste volumes ranging from 0.5 to 3 mL. A random effects mixed model was used to determine the stabilizing point, which was 1 mL of waste. Knowing that only 1 mL of waste is needed will prevent clinicians from obtaining extra waste and discarding blood needlessly.

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