Factors that may impact a specimen sent through a pneumatic tube system:
(1) excessive air pressure
(2) excessive vibration
(3) excessive G forces
(4) exposure to temperature along the tubing route (should have a minimal effect unless the carrier gets stopped for a period)
The effects of pneumatic transport should be minimal if:
(1) the carrier is pressure sealed
(2) the outer shell of the carrier is not defective
(3) the specimens are properly loaded with adequate foam padding
(4) the pneumatic tube system has been installed and is operating properly
(5) the tube has not become lost in the system
(6) the specimen tubes are filled completely
A pneumatic tube system may have been installed properly only to become problematic when there is new construction or a modification is made.
Tests that may be affected by transport in a pneumatic tube system:
(1) higher PaO2 in a blood gas specimen (absent if sent in a pressure sealed tube)
(2) shortening of the PT and aPTT (because of platelet activation)
(3) increases in LDH and potassium (because of red cell hemolysis)
A problem can be detected by analyzing a split sample with one part transported by the pneumatic tube and the other transported by hand to the laboratory. Both samples should be run on the same instrument, ideally at the same time and in replicate.
