Biospecimen Integrity and Short-Term Analyte Stability after Pneumatic Tube Transport: Validation and Pressure Optimization of the TEMPUS 600 System in a Tertiary Care Hospital.

BACKGROUND

Pneumatic tube systems (PTS) reduce preanalytical delay but impose mechanical stress that can hemolyse specimens. We validated the TEMPUS 600 PTS at a tertiary hospital and sought an operating pressure that minimized transport-related hemolysis.

METHODS

Specimens were those already collected for physician-ordered testing; the routine draw was divided between two smaller evacuated tubes of the same type, so no additional blood or urine was taken. In 80 patients, one 2.5 mL serum tube was hand-carried and one was sent by PTS at 1.28 bar; later the same day, the retained whole-blood residual of the hand-carried tube was sent at 1.26 bar, and five hemolysis-sensitive markers were compared by repeated-measures ANOVA. After 1.26 bar was implemented, PTS and manual transport were compared in 120 paired serum specimens (28 analytes) and 80 paired urine specimens (6 analytes), reported as bias following CLSI EP09. Turnaround time (TAT) was compared for the year before and after implementation.

RESULTS

The hemolysis index differed across conditions (F[2,158] = 21.84, p < 0.001) PTS at 1.28 bar exceeded its contemporaneous manual control (10.20 vs. 6.22; p < 0.001), whereas at 1.26 bar, no difference from the manual baseline was detected (6.39 vs. 6.22; p = 0.79). Lactate dehydrogenase (LDH) and potassium behaved likewise. At 1.26 bar, bias was small and bidirectional (serum +6.36% to -14.64%; urine +3.90% to -6.94%). All three TAT components were shorter after implementation (p < 0.001).

CONCLUSIONS

Transport at 1.28 bar was associated with higher hemolysis index, LDH, and potassium than manual transport, and these elevations were no longer detected at 1.26 bar. Because the settings were evaluated sequentially and no equivalence margin was predefined, the findings support site-specific validation and operational optimization of PTS rather than a claim of equivalence.