(P-PB-18) Impacts Of Preanalytical Blood Collection And Storage Variables On Quantra® QPlus

The Quantra® Hemostasis Analyzer is an in vitro point-of-care viscoelastic test (VET) device that measures a series of coagulation and clot lysis parameters using a citrated whole blood (WB) sample. The effects of pre-analytical variables are crucial for the correct utilization and interpretation of these devices. Herein, the effects of WB anticoagulation, anticoagulant species, sample temperature, and sample age were assessed on Quantra® QPlus results.

Study

Design/Methods:

Anticoagulation Extent

Blood:Citrate ratios (9:1, 7:1, 5:1, 3:1 and 2:1) that vary from standard blue top evacuated tubes (9:1) were created in sample tubes and tested in duplicate (n=2) at one-hour post-venipuncture, both at room temperature and under refrigerated conditions (2-8°C).

Anticoagulant Species

CPDA volume was varied in S-Monovette® tubes to create Blood:CPDA ratios (9:1, 7:1, and 5:1) that vary from standard blood donation bags (7:1) and were tested in duplicate (n=2) at one-hour post-venipuncture.

Sample Age

A 7:1 Blood:CPDA volume ratio was used for collection. Samples were stored upright, refrigerated at 2-8°C and tested in duplicate (n=2) immediately and at several timepoints. A platelet count was retrieved at each timepoint.

Results/Findings:

With increasing citrate, clot time (CT) and clot time with heparinase (CTH) increased, and clot stiffness (CS), platelet contribution to clot stiffness (PCS), and fibrinogen contribution to clot stiffness (FCS) oscillated minimally. Only at a 3:1 Blood:Citrate volume ratio, or lower, were CT and CTH either prolonged or non-reportable (results fell outside of the Quantra’s reportable range), while CS, PCS, and FCS distinctly decreased from their 9:1 counterpart.

Cold storage for one hour increased CT and CTH at approximately half the magnitude of their room temperature analogs. Cold-stored and room temperature CS, PCS, and FCS both minimally oscillated.

CPDA anticoagulation followed similar trends to citrate, except that CPDA CS, PCS, and FCS showed a greater decrease.

One-week cold storage in CPDA showed a steady decline in platelet count, CS , PCS, and FCS, whereas CT and CTH trended inconsistently. Stiffness trendlines modeled with an exponential fit showed the greatest correlation coefficients, pointing to a likely negative feedback loop in coagulation capacity as metabolic products accumulate and platelets lose function over time.
 

Conclusions:

Samples became hypo coagulable as anticoagulant content, sample age, and time spent unrefrigerated increased. These findings demonstrate the impact of blood collection and sample handling variables on VET results.