A tube system moves a specimen in seconds instead of minutes, but the line's acceleration and vibration change some results. On one hospital line the peak acceleration reached 10 to 22 g depending on the device, day-to-day variation on the same route was 4 to 39 per cent, and two routes were predicted to raise lactate dehydrogenase (LD) by 20 per cent or more (Farnsworth et al., Clin Chem 2019).
In another hospital's system, 48 routine chemistry, haematology, coagulation and blood gas tests showed no clinically significant difference (Pupek et al., Clin Chem Lab Med 2017). Because installations differ, approval is given to a route and combination, not to a specimen type.
A combination covers the specimen tube, primary and secondary packaging, carrier capsule, sending and receiving stations and speed setting. The line has no temperature control, so for a specimen that needs the cold chain the capsule temperature is measured. Secondary packaging and absorbent material handle leaks, the line's cleaning procedure is defined and every event is recorded. A specimen not on the list goes by hand.