Pneumatic Tube System Research Articles

How Telephone Calls Optimized Our Pneumatic Tube System

How Telephone Calls Optimized Our Pneumatic Tube System

Validation of the Pneumatic Tube System and its Impact on Troponin I Turnaround Time in a Level I Trauma Center

Validation of the Pneumatic Tube System and its Impact on Troponin I Turnaround Time in a Level I Trauma Center

Random variation and systematic error caused by various preanalytical variables, estimated by linear mixed-effects models

BackgroundWe wanted to determine whether specific, preanalytical sample handling increases preanalytical variation and bias test results compared with optimal handling. MethodsBlood was collected into 4 serum-separation tubes from each arm of 60 outpatients. In 30 of the patients, half of the tubes were transported in the pneumatic tube system, while the other half were manually delivered. In the remaining patients, the blood samples were collected using 21-gauge straight needles (green needles) and 23-gauge butterfly needles. Half of the tubes were mixed by inverting 5–6 times, and the other half by one inversion. Linear mixed-effects models were used as statistical method. ResultsTransporting samples in the pneumatic tube system caused a significant bias to the results for LD (4.5U/L, p<0.001) and magnesium (0.0021mmol/L, p=0.003). For CK and glucose, the preanalytical variation was significantly higher for samples transported in the pneumatic tube system vs manual delivery. Using butterfly needles resulted in lower values (p<0.05) for calcium (−0.0072mmol/L), CK (−0.75U/L) and LD (−1.6U/L) compared with 21-gauge needles. The preanalytical variation for ALP was significantly higher with butterfly needles. ConclusionsThe specific sample handling had significant but small random and systematic effects on results for some analytes.

Dispositif pneumatique pour le transport des produits sanguins labiles

Blood product transport from blood bank to the patient care areas of hospitals is a key step in the transfusion process. The pneumatic tube system is now widely used in hospitals. Strict performance specifications must be respected to guarantee blood safety: robustness, easy to use and respect the constraints imposed to blood products. To secure the disposal of blood products ordered to a carrier (delivery step), a security device must be deployed (video camera, barcode reading, fax, chip), allowing in particular to limit the risk of addressing error when sending (in the case of device with several arrival stations) or picked up by the wrong carrier.

Alterations in rotation thromboelastometry (ROTEM®) parameters: point-of-care testing vs analysis after pneumatic tube system transport

Thromboelastometry as point-of-care (POC) testing enables the analysis of the clotting process at the bedside, providing rapid results to guide haemostatic therapy. However, POC testing utilizes medical staff who are managing critically ill patients, as non-laboratory personnel may not be sufficiently trained to run the devices. To resolve these problems, thromboelastometry can be performed in the central laboratory and rapid transport of samples can be accomplished via a pneumatic tube system (PTS). This study compares thromboelastometry parameters of blood samples analysed immediately with those analysed after PTS transport. In patients with normal haemostasis, two arterial blood samples were collected from each patient (n=92) in citrated plastic tubes to investigate the assays INTEM (n=35), EXTEM (n=27), and FIBTEM (n=30). One blood sample was analysed immediately, the other sample after PTS transport. Thromboelastometry was performed using a single ROTEM(®) device. The mean clot firmness values were significantly lower for PTS samples in both the INTEM (-0.7 mm cf. -1.1 mm) and EXTEM (-1.4 cf. -1.7 mm) assays. INTEM coagulation time (CT) was significantly lower in PTS samples with a mean difference of -13 s. EXTEM CT was significantly higher in PTS samples with a mean difference of +3.9 s. Thromboelastometry parameters of blood samples analysed after PTS transport are significantly altered compared with those analysed immediately. However, in patients with normal haemostasis, the alterations were small and without clinical consequence, implying that analysis after PTS transport is an acceptable alternative to prompt analysis at the bedside. Further studies should focus on patients with impaired haemostasis.

Sample transport by pneumatic tube system alters results of multiple electrode aggregometry but not rotational thromboelastometry

Pneumatic tube systems (PTS) present a convenient way for blood sample transport in medical facilities. Associated preanalytical interference in various tests is largely unknown. Implementing point-of-care coagulation management at our institution, we investigated multiple electrode aggregometry (MEA) and rotational thromboelastometry (ROTEM) after PTS transportation. Whole blood samples from patients undergoing general or trauma surgery were analysed by MEA after collection (baseline, ‘0 × PTS’) and sent on a predefined PTS track (n = 12). MEA was repeated after samples travelled the track 4 (‘4 × PTS’), 8 (‘8 × PTS’) and 12 times (‘12 × PTS’) and compared with stationary controls analysed at the same time. Samples for ROTEM (n = 6) were analysed after collection and travelling the track 12 times. An acceleration detector recorded g-forces on the PTS track. At ‘0 × PTS’ no significant differences in MEA results were detected. Values were significantly lower for transported samples compared with controls (‘4 × PTS’ to ‘12 × PTS’, p < 0.001). Furthermore, MEA results of PTS samples were significantly decreased for ‘4 × PTS’ to ‘12 × PTS’ compared to baseline (p < 0.001). Except for the clotting time in EXTEM PTS transport did not significantly alter results for investigated ROTEM parameters, compared with baseline and stationary controls. Acceleration detector readout revealed alternating g-forces between −6.3 and +5.9 during transport. PTS transport caused invalid results in MEA while only one ROTEM parameter was found to be affected in this study. Variable acceleration during transport provides a potential reason for platelet activation. The authors recommend sample transport by hand or the device to be placed patient-side when MEA is performed.

Early recognition of reverse pseudohyperkalemia in heparin plasma samples during leukemic hyperleukocytosis can prevent iatrogenic hypokalemia

ObjectivesTo investigate the cause of apparent hyperkalemia in leukemic heparin plasma. Design and methodsLithium heparin plasma and serum samples from a patient with chronic lymphocytic leukemia (CLL) with hyperleukocytosis were transported by either a pneumatic tube system or manual transport and analyzed either immediately or after 4h. ResultsPneumatic tube transported samples resulted in higher plasma potassium levels than manually transported samples. Serum potassium was lower than plasma potassium, confirming the suspicion of “reverse” pseudohyperkalemia. Letting the pneumatic tube transported samples stand on the bench for 4h before centrifugation surprisingly resulted in decreased or unchanged plasma potassium. ConclusionsThe reverse pseudohyperkalemia in heparin plasma samples from a CLL patient was caused by pneumatic tube transport. Our results suggest extracellular leakage of potassium, followed by active transport of potassium into intact leukemic cells. This is the first Swedish case of reverse pseudohyperkalemia in a CLL patient, where clinical suspicion of false hyperkalemia and awareness of the phenomenon lead to a rapid laboratory diagnosis. The demonstration of reverse pseudohyperkalemia prevented potentially dangerous medical interventions, such as potassium lowering treatment.

A Comprehensive Validation of the Pneumatic Tube System for Transporting Blood Products

A Comprehensive Validation of the Pneumatic Tube System for Transporting Blood Products

Effect of blood collection tubes on the incidence of artifactual hyperkalemia on patient samples from an outreach clinic

BackgroundAn offsite satellite clinic of the University of Chicago Medical Center (UCMC) requested an investigation by the Clinical Chemistry Laboratory (CCL) into several cases of possible falsely elevated potassium (K+) values in their patients. Bloods for K+ and chemistry profiles are routinely collected in mint-green, heparinized plasma separator tubes (PST), centrifuged, and transported by courier from satellite clinic to CCL within several hours. Samples from on-site phlebotomy areas are similarly collected but sent uncentrifuged to CCL via a pneumatic tube system within minutes of collection. MethodsOur investigations included extensive QC and QA review of UCMC onsite and offsite outpatient clinics, reference range studies using PST and serum separator tubes (SST), assessment of pre-analytic handling of specimens, including transportation simulation study, and comparison of K+ results for samples collected simultaneously using PST and SST tubes at an offsite clinic. ResultsOur transportation simulation demonstrated elevations in K+ concentrations following sample jostling and perturbations. We also observed RBC escape across the gel barrier further contributing to K+ elevations. ConclusionSerum is preferred sample type for an offsite clinic.

The effects of pneumatic tube system transport on ROTEM analysis and contact activation assessed by thrombin generation test

Thromboelastometry (ROTEM) is a popular point-of-care test. It generates results quickly and may benefit individualised guided haemostatic therapy. However, processing of specimens by non-technicians might decrease the quality and reproducibility of results. Centralised laboratory equipment receiving specimens through a pneumatic tube system (PTS) could avoid this. This study aimed to evaluate the influence of PTS transport on ROTEM results and its contribution to contact activation assessed by thrombin generation (TG). MethodsSpecimens from 44 patients were drawn immediately after arterial puncture. Two were anticoagulated by citrate and two by citrate/corn trypsin inhibitor, a Factor XIIa pathway inhibitor. Both types of samples were transported by walking and PTS. Subsequently, analysis was performed: ROTEM on citrated blood, and TG on citrated and corn trypsin inhibitor (CTI) blood using either 0 or 1 pM tissue factor (TF). ResultsIn ROTEM analysis the NATEM assay showed significant differences. The EXTEM assay revealed small significant differences for clot formation time: 65seconds (SD±20) versus 67seconds (SD±17), and alpha angle 79° (SD±3) versus 77° (SD±3). The results remained within reference range. TG was not significantly affected by the type of tube transport, independent of the amount of TF. ConclusionPTS for ROTEM analysis is feasible except for NATEM assays. The amount of contact activation via Factor XIIa in terms of TG is independent of transport type. However, due to the different characteristics of pneumatic systems, hospitals should check its impact on the results before introducing this route of transport.

The effect of pneumatic tube system on complete blood count parameters and thrombocyte donation in healthy donors

This paper is the first report whether or not pneumatic tube system affects the selection of apheresis donors according to the results of complete blood count. According to the apheresis guidelines, hemoglobin level must be ⩾12.5g/dL and platelet level ⩾150/μL to be a donor. Paired blood samples of 26 healthy volunteers were transported by either hand delivered or a pneumatic tube system to the laboratory. No statistically significant differences were observed in order to mean values of routine complete blood cell count and white cell differential parameters that were send for selection of apheresis donor before the procedure. Therefore, all healthy volunteers decided as a donor according to the laboratory results independent from transport method.

Assessing Pneumatic Tube Systems with Patient-Specific Populations and Laboratory-Derived Criteria

To the Editor: The October 2011 issue of Clinical Chemistry highlights the importance of monitoring pneumatic tube systems (PTSs) to control preanalytical factors that may affect laboratory results (1, 2). Two important themes emerge: ( a ) the possible requirement of more-frequent monitoring if the PTS produces changes in the 3-axis acceleration (i.e., forces) and ( b ) consideration for specific populations of patients (i.e., hematology and/or oncology patients) whose blood samples may be more susceptible to PTS. As Felder noted, the work by Streichert et al. may usher in a new practice for monitoring PTS by means of data loggers (1, 2); however, in the interim, laboratories will be required to monitor PTSs with split-sample testing. In this regard, the number of studies and approaches that have assessed the impact of PTSs on the quality of samples has been surprisingly limited (3). Moreover, the available guidelines have mainly suggested that PTSs be evaluated and that certain analytes may be affected by the automated system (e.g., lactate dehydrogenase), whereas others (e.g., aspartate aminotransferase) may not (4). Additional questions arising from the study of Streichert et al. are whether samples from healthy …

Pseudohyperkalaemia associated with leukaemic cell lysis during pneumatic tube transport of blood samples

Pseudohyperkalaemia is relatively uncommon in children, but needs to be considered in cases where extreme hyperkalaemia is associated with normal renal function. A previously well 12 year-old boy presented with new onset T cell acute lymphoblastic leukaemia associated with a high peripheral blood white cell count. Plasma biochemistry tests on a blood sample sent to the laboratory using a pneumatic tube system showed a high plasma potassium level of 16.6 mmol/l, with otherwise normal electrolytes and renal function. A 12-lead electrocardiogram was normal, with no changes suggestive of hyperkalaemia. Pseudohyperkalaemia was suspected, and further samples transported to the laboratory by foot showed normal plasma potassium levels. It was subsequently demonstrated that the pseudohyperkalemia was due to the lysis of leukaemic white cells during the transport of blood samples from the ward to the laboratory within the pneumatic tube system. Paediatricians caring for children with haematological malignancies need to be aware of this cause of pseudohyperkalaemia so that unnecessary treatment, including the commencement of acute dialysis, is avoided. We recommend that blood samples collected from children with high white cell count malignancies are transported to the laboratory by foot rather than in pneumatic tube systems.

Effect of Pneumatic Tube Delivery System Rate and Distance on Hemolysis of Blood Specimens

We evaluated the effects of pneumatic tube system (PTS) transport rates and distances on routine hematology and coagulation analysis. PTS effects on centrifuged blood samples were also examined. The study was completed at Dicle University Hospital, which has the longest pneumatic tube system in Turkey. Blood samples were collected at three different locations within the hospital and an emergency department, and delivered to the central laboratory by the PTS or a human carrier. Samples were transported at different rates and over varying distances. Each specimen's potassium (K) and lactic dehydrogenase (LDH) levels, in both the serum and plasma, were tracked to monitor hemolysis. Measurements of LDH and K were obtained using heparin or citrate. A positive correlation was observed between distance and hemolysis in serum samples transported at 4.2 m/sec, and at 3.1 m/sec for more than 2200 m (r = 0.774 and r = 0.766, respectively). Distance and hemolysis were also correlated in non-centrifuged samples (r = 0.871). The alterations in plasma LDH and K levels at different rates and PTS lengths were not statistically significant. The rate of hemolysis in PTS transported samples, dependent on PTS length and rate, may seriously affect routine tests of non-centrifuged samples.

Platelet concentrate transport in pneumatic tube systems – does it work?

Blood sample transport via pneumatic tube systems (PTS) reduces the turnaround time of laboratories, but it might influence analysis results. Its effect on platelet concentrates (PCs) is not known. Platelet function was investigated after single and multiple PTS transport in comparison with storage and irradiation. Optical and impedance aggregation, CD-62, and microparticles changed as a result of storage, but not due to transport. Irradiation lowered platelet function independently. Multiple transport impaired thrombin receptor-activating peptide-induced aggregation. This investigation demonstrates the feasibility of PTS transport. As platelet function depends on storage, it may be more important to transfuse fresh PCs.

Effect of acceleration forces during transport through a pneumatic tube system on ROTEM® analysis

ROTEM® is considered a helpful point-of-care device to monitor blood coagulation in emergency situations. Centrally performed analysis is desirable but rapid transport of blood samples is an important prerequisite. The effect of acceleration forces on sample transport through a pneumatic tube system on ROTEM® should be tested at each institution to exclude a pre-analytical influence. The aims of the present work were: (i) to investigate the effect of pneumatic tube transport on ROTEM® parameters; (ii) to compare blood sample transport via pneumatic tube vs. manual transportation; and (iii) to determine the effect of acceleration forces on ROTEM® parameters. This is a single centre study with 20 healthy volunteers. Five whole blood samples were transferred to the central haematology laboratory by either normal transport or pneumatic delivery with different speed and acceleration forces. EXTEM, INTEM, FIBTEM and APTEM were analysed in parallel with two ROTEM® devices and compared. Acceleration forces were measured during transport with two different instruments. Increment of transport time, speed and distance resulted in an augmentation of acceleration forces and peaks. All results of the ROTEM® analysis after manual transport or pneumatic delivery were within normal range. However, increase in acceleration forces resulted in minimally but statistically significant changes in multiple ROTEM® parameters. The higher the acceleration forces, the more ROTEM® parameters are influenced. Acceleration forces during transport through a pneumatic tube system have an influence on ROTEM® parameters. Prior to transfer blood samples via pneumatic tube system these influences should be tested to exclude clinically relevant blood coagulation activation in vitro.

Speed of sample transportation by a pneumatic tube system can influence the degree of hemolysis

The objective of the study was to find the incidence of hemolysis in samples transported through a pneumatic tube system (PTS) at different speeds. This prospective observational study was done in three phases: "short distance and high speed (115 m at 3 m/s)", "long distance and high speed (225 m at 3 m/s)" and "short distance and slow speed (115 at 2 m/s)". Fifty-two, 215 and 45 serum tube pairs, respectively, were evaluated in these three phases. A set of tubes was sent by PTS while the other was hand-carried. Samples were analyzed for supernatant hemoglobin (Hb), potassium (K+) and lactate dehydrogenase (LD). Mean transit time of samples through the PTS was much shorter as compared to human courier in all three phases. LD was elevated in PTS arm in the "short distance and high speed" phase and in the "long distance and high speed" phase, all three indices of hemolysis - Hb, K+ and LD - showed elevation in the PTS arm. However, at "short distance and slow speed" phase, there was no hemolysis in the PTS arm. Hospitals should validate their PTS before use and, by altering speed of sample transportation, hemolysis may be obliterated.

Determination of Hemolysis Thresholds by the Use of Data Loggers in Pneumatic Tube Systems

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. 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. 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. 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.

Agreement between paired blood gas values in samples transported either by a pneumatic system or by human courier

Rapid accurate assessment of metabolic derangements is crucial in the critically ill. We evaluated if arterial blood gas (ABG) samples transported through a pneumatic tube system (PTS) agreed with values transported by a human courier. In this prospective study of 50-paired ABG samples, the couriered reference ABG was compared with those transported by PTS. Agreement was summarised by the mean difference with 95% limits of agreement (LOA) and Lin's concordance correlation (pc). The mean (±SD) time from sampling to analysis was 35.7±23.2 (courier) and 38.6±22.1 (PTS) minutes. Agreement was good between courier and PTS for pH, PaCO(2), bicarbonate, oxygen saturation and PaO(2) values (pc>0.97). Although the mean difference in PaO(2) values between PTS and courier was small (-0.9 mm Hg) and the agreement was good, individual differences were clinically significant (95% LOA -40.8 to 39.0). For PaO(2) <160 mm Hg, analysis of PTS samples yielded erroneously high PaO(2) values and vice versa for PaO(2)>160 mm Hg compared to manual courier. This suggested exaggerated oxygen movement between the blood sample and air in the PTS. In this study, analysis of samples transported through the PTS resulted in clinically unacceptable PaO(2) values. Delay in transport and analysis of ABG samples should be avoided and samples transported manually if they cannot be assessed on-site.

Laboratory-based ROTEM® analysis: implementing pneumatic tube transport and real-time graphic transmission

ROTEM(®) is considered a helpful point-of-care device to monitor blood coagulation. Centrally performed analysis is desirable but rapid transport of blood samples and real-time transmission of graphic results are an important prerequisite. The effect of sample transport through a pneumatic tube system on ROTEM(®) results is unknown. The aims of the present work were (i) to determine the influence of blood sample transport through a pneumatic tube system on ROTEM(®) parameters compared to manual transportation, and (ii) to verify whether graphic results can be transmitted on line via virtual network computing using local area network to the physician in charge of the patient. Single centre study with 30 normal volunteers. Two whole blood samples were transferred to the central haematology laboratory by either normal transport or pneumatic delivery. EXTEM, INTEM, FIBTEM and APTEM were analysed in parallel with two ROTEM(®) devices and compared. Connection between central laboratory, emergency and operating rooms was established using local area network. All collected ROTEM(®) parameters were within normal limits. No statistically significant differences between normal transport and pneumatic delivery were observed. Real-time transmission of the original ROTEM(®) curves using local area network is feasible and easy to establish. At our institution, transport of blood samples by pneumatic delivery does not influence ROTEM(®) parameters. Blood samples can be analysed centrally, and results transmitted live via virtual network computing to emergency or operating rooms. Prior to analyse blood samples centrally, the type of sample transport should be tested to exclude in vitro blood activation by local pneumatic transport system.