# Navigating preanalytical challenges: a real-world study on single-tube pneumatic tube systems

## TL;DR

A new single-tube pneumatic system for labs was tested, showing that delays before transport can affect blood test results.

## Contribution

A novel single-tube pneumatic tube system with LIS integration was developed and evaluated for preanalytical effects.

## Key findings

- LDH levels increased significantly in PTS groups compared to manual delivery, with bias exceeding acceptable limits after delays.
- Glucose showed clinically acceptable variations despite significant changes.
- Hemolysis index remained negative for all tested groups.

## Abstract

Pneumatic tube systems (PTS) accelerate the transport of samples in the laboratory but may lead to preanalytical hemolysis. Samples may rest before transport during busy times, but the effect on test accuracy is unclear. This study presents a novel single-tube PTS with a secondary deceleration device and LIS integration, evaluating its impact on routine biochemical parameters and examining the effects of prolonged sample resting times before PTS transport.

In a prospective study of 34 outpatients, four blood samples per participant were collected in silica-clot activator tubes. Samples were randomly allocated to: immediate PTS transport (Group A), PTS after 15-min rest (B), PTS after 30-min rest (C), or manual delivery (Group D). All samples from each subject were centrifuged and analyzed simultaneously upon arrival. Twenty-two biochemical parameters were measured; results for PTS groups were compared to the manual control, with bias assessed against ±1/2 total allowable error (±1/2TEa).

The hemolysis index (HI) was negative for both PTS and HD groups. Lactate dehydrogenase (LDH) levels were significantly elevated in all PTS groups versus manual delivery (p < 0.001). The bias for LDH was clinically acceptable only for immediate transport (Group A: +3.2%) but exceeded limits after 15- and 30-min rests (Group B: +5.8%; Group C: +10.7%). Glucose showed significant yet clinically acceptable variations. Other parameters remained within acceptable limits.

The single-tube PTS is suitable for transporting blood specimens for biochemical analysis. To maintain the reliability of biochemical results from silica-clot activator tubes, laboratories should minimize pre-transport delays and include resting time as a critical variable in PTS validation protocols.