Sample transport by pneumatic tube system alters results of multiple electrode aggregometry but not rotational thromboelastometry

Abstract

Pneumatic tube systems (PTS) present a convenient way for blood sample transport in medical facilities. Associated preanalytical interference in various tests is largely unknown. Implementing point-of-care coagulation management at our institution, we investigated multiple electrode aggregometry (MEA) and rotational thromboelastometry (ROTEM) after PTS transportation. Whole blood samples from patients undergoing general or trauma surgery were analysed by MEA after collection (baseline, '0 × PTS') and sent on a predefined PTS track (n = 12). MEA was repeated after samples travelled the track 4 ('4 × PTS'), 8 ('8 × PTS') and 12 times ('12 × PTS') and compared with stationary controls analysed at the same time. Samples for ROTEM (n = 6) were analysed after collection and travelling the track 12 times. An acceleration detector recorded g-forces on the PTS track. At '0 × PTS' no significant differences in MEA results were detected. Values were significantly lower for transported samples compared with controls ('4 × PTS' to '12 × PTS', p < 0.001). Furthermore, MEA results of PTS samples were significantly decreased for '4 × PTS' to '12 × PTS' compared to baseline (p < 0.001). Except for the clotting time in EXTEM PTS transport did not significantly alter results for investigated ROTEM parameters, compared with baseline and stationary controls. Acceleration detector readout revealed alternating g-forces between -6.3 and +5.9 during transport. PTS transport caused invalid results in MEA while only one ROTEM parameter was found to be affected in this study. Variable acceleration during transport provides a potential reason for platelet activation. The authors recommend sample transport by hand or the device to be placed patient-side when MEA is performed.

Platelet Function Determined by Flow Cytometry: New Perspectives?

“…After that, vigorous shaking (e.g., pneumatic tube transport) or temperature shifts during transportation to the laboratory have to be avoided, as these procedures have been shown to cause platelet preactivation. 23,24 By including a sample checking for spontaneous platelet preactivation in the flow cytometry panel, it will be possible to find and potentially discard data that are unreliable due to preanalytical activation of the collected platelets (discussed further below). Blood samples should be kept at room temperature prior to analysis, 22 and actions taken to prevent temperature fluctuations.…”

Preanalytical Variables in Coagulation Testing: Setting the Stage for Accurate Results

“…90 Pneumatic tube systems can generally be used to move anticoagulated whole blood specimens from the hospital patient floors to the laboratory for coagulation tests and standard TEG or ROTEM studies, but not for platelet function analysis, including POC platelet function testing, platelet aggregation studies, or THEG platelet function testing (e.g., TEG platelet mapping). [91][92][93] Citrated whole blood tubes to be used for platelet function studies ("platelet aggregation") and associated TEG, ROTEM, and Multiplate whole blood aggregometry studies should be collected as described above, but must sit at room temperature for 30 minutes to allow reequilibration and return of normal platelet function, but no longer than 2 to 4 hours, after which platelet function deteriorates. 94,95 Specimen Processing and Storage…”

“…If only citrate collections tubes are being collected, no discard tube is necessary (unless using butterfly syringe method directly into collection tube) 84 Patients with elevated hematocrits (> 55%) require reduced volume of citrate prior to collection Pneumatic transport systems should not be used for samples that require platelet function testing [91][92][93] For samples that are collected outside the confines of the hospital (e.g., home health and remote facilities), the samples should be transported in containers (e.g., insulated Styrofoam) that assure ambient room temperature (21-24°C)…”

Point of Care Testing in Cardiac Surgery: Diagnostic Modalities to Assess Coagulation and Platelet Function

“…An additional strength of the ROTEM system is that it is a relatively stable platform, with results generally insensitive to collection or transport method [Glas et al, 2013]. The system has also been validated for use in pediatric cardiac cases [Andreasen et al, 2011].…”