Low vacuum (3 mL) rapid serum tubes offer better protection from hemolysis than plasma separator tubes collected in the emergency department

Introduction

Hemolysis is a major source of interference with laboratory testing, especially for the emergency department (ED), leading to longer turnaround times for test results, repeated blood draws, delay in care delivery, and increased hospital costs. Rapid serum tubes (RST) can reduce transport-induced hemolysis, especially for samples sent via the pneumatic tube system, as compared with plasma separator tubes (PST). Previously, studies testing the efficacy of RST used larger volume 5 mL tubes to compare to 4.5 mL PST tubes. In this study, a lower vacuum RST (3 mL) is compared to PST (3.5 mL) for hemolysis reduction.

Methods

Paired PST and RST blood samples from 47 ED patients were included in this study. RST and PST samples were sent via the pneumatic tube system and inspected for degree of clotting prior to centrifugation. All samples were tested within the hour for high-sensitivity troponin (hs-cTnT), hemolysis, lactate dehydrogenase, and potassium.

Results

Degree of hemolysis was significantly lower in fully clotted RSTs compared to PSTs (p = 0.0005). In RSTs that only partially clotted and PSTs, differences in hemolysis rates were non-significant (p = 0.273). The hs-cTnT levels in RST and PST are concordant with a slope of 0.96, an intercept of 1.01 ng/L and an R-squared value of 0.9318.

Conclusion

Fully clotted low-vacuum RSTs provide improved protection from transport-induced hemolysis compared to low-vacuum PSTs or partially clotted RSTs. Low-vacuum RSTs also provided more hemolysis protection than larger volume RSTs previously studied. Clot formation prior to transport is key to the protective mechanism of RST. Blood device manufacturers are encouraged to develop low vacuum RST for use by the ED and other areas with high hemolysis rates.