Diagnostic sample transport via pneumatic tube systems: data logger and their algorithms are sensitive to transport effects

OBJECTIVES

Many hospitals use pneumatic tube systems (PTS) for transport of diagnostic samples. Continuous monitoring of PTS and evaluation prior to clinical use is recommended. Data loggers with specifically developed algorithms have been suggested as an additional tool in PTS evaluation. We compared two different data loggers.

METHODS

Transport types - courier, conventional (cPTS) and innovative PTS (iPTS) - were monitored using two data loggers (MSR145® logger, CiK Solutions GmbH, Karlsruhe, Germany, and a prototype developed at the University Medicine Greifswald). Data loggers differ in algorithm, recording frequencies and limit of acceleration detection. Samples from apparently healthy volunteers were split among the transport types and results for 37 laboratory measurands were compared.

RESULTS

For each logger specific arbitrary units were calculated. Area-under-the-curve (AUC)-values (MSR145®) were lowest for courier and highest for iPTS and increased with increasing recording frequencies. Stress (St)-values (prototype logger) were obtained in kmsu (1,000*mechanical stress unit) and were highest for iPTS as well. Statistical differences between laboratory measurement results of transport types were observed for three measurands sensitive for hemolysis.

CONCLUSIONS

The statistical, but not clinical, differences in the results for hemolysis sensitive measurands may be regarded as an early sign of preanalytical impairment. Both data loggers record this important interval of beginning mechanical stress with a high resolution indicating their potential to facilitate early detection of preanalytical impairment. Further studies should identify suitable recording frequencies. Currently, evaluation and monitoring of diagnostic sample transport should not only rely on data loggers but also include diagnostic samples.

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.

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

Many studies have explored how using a pneumatic tube system (PTS) is related to the hemolysis of blood samples, but their conclusions have been inconsistent. This meta-analysis was to clarify whether using a PTS induces the hemolysis of blood samples. The PubMed, Embase, Scopus, CNKI, CqVip, SinoMed and WanFang databases were searched for studies published between January 1970 and August 2019. The primary outcomes were the hemolysis rate and hemolysis index of blood samples after applying a PTS and manual transportation. We estimated the pooled risk ratio (RR) and the standardized mean difference (SMD), using random-effects models. This meta-analysis included 29 studies covering 3121 blood samples. No significant differences were found between the PTS and manual-transportation groups in the hemolysis rate [RR: 0.99, 95% confidence interval (CI): 0.57 to 1.70], hemolysis index (SMD: 0.19, 95% CI: -0.00 to 0.38), or level of potassium (SMD: 0.05, 95% CI: -0.03 to 0.12), alanine aminotransferase (SMD: 0.00, 95% CI: -0.10 to 0.11), or aspartate aminotransferase (SMD: 0.04, 95% CI: -0.08 to 0.17). However, lactate dehydrogenase (LDH) level was significantly higher in the PTS group than in the manual-transportation group (SMD: 0.20, 95% CI: 0.06 to 0.34). Subgroup analysis revealed that the LDH level was clearly higher in the PTS group than in the manual-transportation group only when the PTS speed was ≥6 m/s or when the PTS distance was ≥250 m. According to this meta-analysis, PTSs were associated with alterations in LDH measurements, so it is sensible that each hospital validates and monitors their PTSs.

Therapeutic turnaround times for common laboratory tests in a tertiary hospital in Kenya

METHODS

We evaluated therapeutic TAT for a tertiary hospital in Western Kenya, using a time-motion study focusing specifically on common hematology and biochemistry orders. The aim was to determine significant bottlenecks in diagnostic testing processes at the institution.

RESULTS

A total of 356 (155 hematology and 201 biochemistry) laboratory tests were fully tracked from the time of ordering to availability of results to care providers. The total therapeutic TAT for all tests was 21.5 ± 0.249 hours (95% CI). The therapeutic TAT for hematology was 20.3 ± 0.331 hours (95% CI) while that for biochemistry tests was 22.2 ± 0.346 hours (95% CI). Printing, sorting and dispatch of the printed results emerged as the most significant bottlenecks, accounting for up to 8 hours of delay (Hematology-8.3 ± 1.29 hours (95% CI), Biochemistry-8.5 ± 1.18 hours (95% CI)). Time of test orders affected TAT, with orders made early in the morning and those in the afternoon experiencing the most delays in TAT.

CONCLUSION

Significant inefficiencies exist at multiple steps in the turnaround times for routine laboratory tests at a large referral hospital within an LMIC setting. Multiple opportunities exist to improve TAT and streamline processes around diagnostic testing in this and other similar settings.

The impact of pneumatic tube system on routine laboratory parameters: a systematic review and meta-analysis

Background:

Pneumatic tube system (PTS) is a widely used method of transporting blood samples in hospitals. The aim of this study was to evaluate the effects of the PTS transport in certain routine laboratory parameters as it has been implicated with hemolysis.

Methods:

A systematic review and a meta-analysis were conducted. PubMed and Scopus databases were searched (up until November 2016) to identify prospective studies evaluating the impact of PTS transport in hematological, biochemical and coagulation measurements. The random-effects model was used in the meta-analysis utilizing the mean difference (MD). Heterogeneity was quantitatively assessed using the Cohran’s

Results:

From a total of 282 studies identified by the searching procedure, 24 were finally included in the meta-analysis. The meta-analysis yielded statistically significant results for potassium (K) [MD=0.04 mmol/L; 95% confidence interval (CI)=0.015–0.065; p=0.002], lactate dehydrogenase (LDH) (MD=10.343 U/L; 95% CI=6.132–14.554; p<10

Conclusions:

This meta-analysis suggests that PTS may be associated with alterations in K, LDH and AST measurements. Although these findings may not have any significant clinical effect on laboratory results, it is wise that each hospital validates their PTS.