Effects of a pneumatic tube system on the hemolysis of blood samples: a PRISMA-compliant meta-analysis

Effects of centrifugation prior to pneumatic tube system transport on routine biochemical and immunological tests of susceptibility to hemolysis

BACKGROUND

Pneumatic tube system (PTS) may be associated with preanalytical hemolysis. The objective of this study was to evaluate the effects of PTS on biochemical and immunological tests susceptible to hemolysis and try to find ways to reduce the result bias caused by PTS.

METHODS

Laboratory parameters were compared between PTS without centrifuging group, PTS after centrifuging group, PTS with serum group, and hand-delivered (HD) group. Studies were performed to access the influence of different PTS transport frequencies on laboratory assays.

RESULTS

PTS transportation resulted in obviously increase in LDH (lactate dehydrogenase) and NSE (neuron-specific enolase) results (LDH: Bias = 17.95%, 95% confidence interval (CI) = -3.13-39.02; p < 0.001; NSE: Bias = 64.26%, 95% CI = -21.29-149.82; p < 0.001; respectively). After pre-centrifugation, no statistical difference was observed in LDH results (Bias = 2.83%, 95% CI = -13.00-18.65; p = 0.737). However, the bias of NSE still reach 19.16% (95% CI = -41.78-80.11), which exceeded the clinical acceptable range (p = 0.017). Both LDH(p = 0.931) and NSE(p > 0.999) show no statistical difference between PTS with serum group and HD group (LDH: Bias = -1.60%, 95% CI = -6.00-2.81; NSE: Bias = -3.68%, 95% CI = -11.35-3.99).

CONCLUSION

PTS can lead to falsely increased LDH and NSE test results. Only loading the centrifuged upper serum in new tubes during PTS transport can eliminate the results bias of NSE.

Investigation of the effects of pneumatic tube transport system on routine biochemistry, hematology, and coagulation tests in Ankara City Hospital

OBJECTIVES

Academics are far from a consensus regarding the effects of pneumatic tube system (PTS) delivery on sample integrity and laboratory test results. As for the reasons for conflicting opinions, each PTS is uniquely designed, sample tubes and patient characteristics differ among studies. This study aims to validate the PTS utilized in Ankara City Hospital for routine chemistry, coagulation, and hematology tests by comparing samples delivered via PTS and porter.

METHODS

The study comprises 50 healthy volunteers. Blood samples were drawn into three biochemistry, two coagulation, and two hemogram tubes from each participant. Each of the duplicate samples was transferred to the emergency laboratory via Swiss log PTS (aka PTS-immediately) or by a porter. The last of the biochemistry tubes were delivered via the PTS, upon completion of coagulation of the blood (aka PTS-after). The results of the analysis in these groups were compared with multiple statistical analyses.

RESULTS

The study did not reveal any correlation between the PTS and serum hemolysis index. There were statistically significant differences in several biochemistry tests. However, none of them reached the clinical significance threshold. Basophil and large unidentified cell (LUC) tests had poor correlations (r=0.47 and r=0.60; respectively) and reached clinical significance threshold (the average percentages of bias, 10.2%, and 15.4%, respectively). The remainder of the hematology and coagulation parameters did not reach clinical significance level either.

CONCLUSIONS

The modern PTS validated in this study is safe for sample transportation for routine chemistry, coagulation, and hematology tests frequently requested in healthy individuals except for basophil and LUC.