Studies on the use of BD Vacutainer® SST II™ and RST™ in general practice: investigation of artefactual hyperkalaemia

Abstract

Background: Current sampling and transport conditions of samples in general practice can result in pseudohyperkalaemia. This study was undertaken to determine, in a general practice setting, whether there is any difference in haemolysis obtained when using BD Vacutainer Õ Rapid Serum Tubes (BD RST) compared with using BD Vacutainer Õ SST TM II Advance Blood Collection Tubes (BD SSTII). Methods: Blood was collected from 353 patients requiring blood sampling who were attending 31 general practitioner practices in Belgium. For each patient, two BD SSTII tubes and two BD RST tubes were drawn in a randomized order. One of each pair of tubes was inverted five times, the other was not. Serum potassium concentration, serum LDH activity and haemolysis index were measured in each sample. Results: There was no significant difference in measured potassium concentration according to tube type (P ¼ 0.16). Measured LDH activities were 1.7% higher in serum collected into BD SSTII tubes compared to BD RST tubes (P ¼ 0.02). When comparing serum from unmixed BD RST with BD SSTII tubes, there was a slight reduction in the haemolysis index but no significant difference in measured potassium concentration or LDH activity. Risk of hyperkalaemia was 4.8 times higher in serum from tubes that were incompletely filled compared to those that were filled with the correct amount of blood. Conclusion: Both types of blood tubes are suitable for the measurement of serum potassium and LDH in patients from general practice. Tube inversion does not improve the accuracy of either serum potassium or LDH measurement. Blood tubes should be filled to the level recommended by the manufacturer to avoid artefactual increases in measured serum potassium concentration and LDH activity.

Evaluation of the BD Vacutainer® RST blood collection tube for routine chemistry analytes: clinical significance of differences and stability study

“…Similarities and differences in the concentration of tested analytes measured in RST have been reported previously ( 7 , 12 , 18 ). In the study of Ng and Yeo ( 7 ), no differences in the concentrations of test analytes were observed, while study Dimeski et al .…”

“…Also, Huyghe et al . ( 18 ) observed that measured serum LD activity was significantly lower among specimens collected in RST than those collected in SST II. As the study of Parenmark and Landberg ( 19 ) showed that mixing tubes immediately after venipuncture can increase hemolysis index and that mixing blood samples after venipuncture is not mandatory for all types of tubes ( 19 , 20 ), all hemolysed samples were excluded from our study in order to prevent the influence of hemolysis, although inverting the tubes versus non inverting did not significantly affect LD activity ( 18 ).…”

Comparison of BD Vacutainer® Rapid Serum Tube and plasma for haemolysis markers in the emergency department

“…7 In our study, samples were all collected via a cannula connector valve. Other collection factors such as incompletely filled collection tubes may also contribute to spurious potassium and LD elevations 2 ; however, specimens in our study were all collected by nursing staff trained in correct blood collection technique.…”

“…This may be explained by faster clotting giving a 'more compact and robust clot, which results in less red cell disruption'. 2 Previous studies, however, were performed in settings with low rates of haemolysis (42% of samples haemolysed) 1,2 and the effect has not been evaluated where higher rates of haemolysed samples may be expected.…”

Comparison of the SST ™ II with RST tubes for biochemistry parameters in emergency laboratory

“…Adding thrombin promotes rapid clotting of the blood. An RST can be centrifuged 5 minutes after collection at 4500 rpm to provide a high-quality serum specimen, which can be sampled directly from the primary tube and can be used to measure a wide range of biochemistry parameters in routine and emergency laboratories [4,5].…”