Speed of sample transportation by a pneumatic tube system can influence the degree of hemolysis

Background: The objective of the study was to find the incidence of hemolysis in samples transported through a pneumatic tube system (PTS) at different speeds. Methods: This prospective observational study was done in three phases: "short distance and high speed (115 m at 3 m/s)", "long distance and high speed (225 m at 3 m/s)" and "short distance and slow speed (115 at 2 m/s)". Fifty-two, 215 and 45 serum tube pairs, respectively, were evaluated in these three phases. A set of tubes was sent by PTS while the other was hand-carried. Samples were analyzed for supernatant hemoglobin (Hb), potassium (K+) and lactate dehydrogenase (LD). Results: Mean transit time of samples through the PTS was much shorter as compared to human courier in all three phases. LD was elevated in PTS arm in the "short distance and high speed" phase and in the "long distance and high speed" phase, all three indices of hemolysis - Hb, K+ and LD - showed elevation in the PTS arm. However, at "short distance and slow speed" phase, there was no hemolysis in the PTS arm. Conclusions: Hospitals should validate their PTS before use and, by altering speed of sample transportation, hemolysis may be obliterated.