Influence of pneumatic tube delivery system on laboratory results

Introduction: The pneumatic tube system (PTS) is an automated and fast modality of transportation of biological samples, but it has been reported to induce preanalytical errors. Aim: To study the influence of transportation by PTS on biochemistry tests which are particularly sensitive to haemolysis and atmospheric pressure variation. Materials and methods: We compared laboratory results of arterial blood gas, sodium, potassium, chloride, lactate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, glucose and haemolysis index of samples conveyed simultaneously by PTS and by courier. Results: We recruited 30 patients from the sampling roomand 40 patients from the intensive care unit. Transport through PTS resulted in a significant increase in aspartate aminotransferase and potassium without exceeding the limits of acceptability. Potassium was significantly more increased for samples transported in a higher speed line (p =.048) but without exceeding the limits of acceptability. No significant impact was noted on haemolysis indices. The pO(2) variations due to PTS transportation exceeded the limit of acceptability with significant intra-individual variations. Conclusion: Our PTS is validated for biochemistry tests results. It reduces turnaround times without affecting sample quality. However, the interpretation of arterial blood gas results should be careful for samples transported by PTS.