Key result
Discarding 1 mL of blood from EDTA-locked PICCs shows acceptable lab agreement for most analytes.
Why the study?
Optimal discard volumes for blood sampling after use of EDTA-based catheter lock solutions in vascular access devices remain uncertain.
Does discarding 1 mL of blood provide reliable laboratory testing after use of 4% tetrasodium EDTA catheter lock solution in patients with PICC?
Observational (n=10)
Does discarding 1 mL of blood provide reliable laboratory testing after use of 4% tetrasodium EDTA catheter lock solution in patients with PICC?
Discarding 1 mL of blood after using a 4% tetrasodium EDTA lock solution in PICCs appears sufficient for reliable laboratory testing, though larger studies are needed.
May support 1 mL discard for reliable PICC labs after EDTA lock; hypothesis-generating and requires larger validation before practice change.
BACKGROUND: Vascular access devices (VADs) are increasingly used for blood sampling, yet optimal discard volumes remain uncertain, particularly when EDTA-based lock solutions are used. OBJECTIVE: To evaluate whether discarding 1 mL is sufficient for reliable laboratory testing after use of 4% tetrasodium EDTA catheter lock solution (Kitelock™) in PICC. METHODS: In a prospective study, 10 patients with single-lumen peripherally inserted central catheters (polyurethane, 4F, open-ended) underwent blood sampling after flushing the catheter and discarding 1 mL, corresponding to approximately two dead spaces for the shortened catheters used. Five consecutive tubes were analyzed per sample type (biochemistry, hematology, coagulation). Agreement with the reference tube (tube 5) was assessed using Bland-Altman plots, clinically acceptable intervals (CAI), intraclass correlation coefficient (ICC), and Lin's concordance correlation coefficient (CCC). RESULTS: In the first tube, several analytes reached 10/10 comparisons within the CAI (urea, sodium, potassium, calcium, magnesium, alkaline phosphatase, erythrocytes, hematocrit, MCV, leucocytes, thrombin time). Others showed 9/10 comparisons (total protein, albumin, chloride, hemoglobin, thrombocytes, APTT, prothrombin time, fibrinogen). Only creatinine reached 8/10. CONCLUSIONS: Discarding 1 mL appeared sufficient for reliable testing after Kitelock™ use in our cohort, but confirmation in larger studies is warranted.
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Rajdl et al. (2025) conducted an observational in Patients with single-lumen peripherally inserted central catheters (n=10). Discarding 1 mL of blood after 4% tetrasodium EDTA catheter lock solution vs. Reference tube (tube 5) was evaluated on Agreement of the first tube with the reference tube within clinically acceptable intervals. Discarding 1 mL of blood after using a 4% tetrasodium EDTA lock solution in PICCs yielded acceptable agreement with reference samples for most analytes (e.g., 10/10 comparisons for sodium).
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