Determination of hemolysis thresholds by the use of data loggers in pneumatic tube systems.

BACKGROUND Pneumatic tube systems (PTSs) for the transport of blood samples are regaining popularity in medical centers after earlier reports that their use could introduce preanalytical distortions such as hemolysis and changes in blood gases. METHODS We drew duplicate blood samples from 30 volunteers. One sample was hand transported, and the other sample was transported through a PTS together with a mini-data logger that provided continuous measurements of temperature, humidity, pressure, and acceleration. After transport the samples were analyzed at the same time. We looked for possible relationships of the transport method and the parameters measured by the data loggers with differences in hematological parameters, standard clinical chemistry analyses, blood coagulation, erythrocyte sedimentation rate, and blood gas analysis. RESULTS There were no significant differences in temperature, humidity, and pressure between the methods of transport, but we observed significant differences in 3-axis accelerations. The combined effect of these forces could be described by the right-tailed area under the vector sum acceleration distribution. Our data show that this area correlated with PTS speed and that PTS speed and the area under the curve exhibited a direct relation to the degree of hemolysis. CONCLUSIONS Assessment of 3-axis acceleration by use of data loggers can be used to identify preanalytical deviations that result from the transportation of blood samples in PTSs. Our approach could be used for the evaluation and regular control of PTSs without the need for repeated blood drawing and laboratory analyses.