Background: The use of pneumatic tube system (PTS) transport has gained considerable popularity in modern hospitals but is also associated with sample hemolysis. The potential contribution of PTS-associated acceleration forces to high hemolysis rates observed in the emergency department (ED) has not been investigated before and can be easily examined nowadays using smartphone applications. The first aim of our study was to investigate whether our PTS induces hemolysis of patient samples obtained from our ED. We also explored a potential correlation between hemolysis index (HI) on the one hand and acceleration forces during PTS transport or other potential causes of hemolysis related to patient characteristics on the other for two different blood sampling techniques.
Methods: Blood samples from 100 ED patients were collected in one Sarstedt S-Monovette® serum tube (PTStransported to laboratory) and two BD Vacutainer® serum tubes (one PTS-transported and one hand-carried). For all serum samples HI was measured. A smartphone was sent along with the samples in order to register accelerations during transport. Patient’s erythrocyte sedimentation rate (ESR), mean corpuscular volume (MCV), hematocrit, total cholesterol, low density lipoprotein (LDL), and high-density lipoprotein (HDL) concentration were determined as well.
Results: Hemolysis rate was only 1 - 4% and 5% for PTS and hand-carried transport, respectively. Calculated acceleration vector sums for PTS transport from the ED to laboratory reached up to 131.49 m/second2 (13.40 g). No correlation could be demonstrated between HI on the one hand and acceleration forces acting on the samples during PTS transport or ESR, MCV, hematocrit, and HDL concentration on the other. However, an inverse correlation was noted between HI and cholesterol (total and LDL) concentration in serum tubes transported via PTS, though not in those carried by hand.
Conclusions: We demonstrated that our PTS does not induce or contribute to hemolysis of ED patient samples, even at high acceleration vector sums up to 13 g. Technological advancements such as the development of smartphone applications offer the ability to regularly monitor acceleration forces during PTS transport of patient samples. Low total cholesterol and LDL concentrations may affect the erythrocyte membrane fluidity, making erythrocytes more prone to hemolysis.