Contamination of lithium heparin blood by K2-ethylenediaminetetraacetic acid (EDTA): an experimental evaluation

Introduction:

The contamination of serum or lithium heparin blood with ethylenediaminetetraacetic acid (EDTA) salts may affect accuracy of some critical analytes and jeopardize patient safety. The aim of this study was to evaluate the effect of lithium heparin sample contamination with different amounts of K₂EDTA.

Materials and methods:

Fifteen volunteers were enrolled among the laboratory staff. Two lithium heparin tubes and one K₂EDTA tube were collected from each subject. The lithium-heparin tubes of each subject were pooled and divided in 5 aliquots. The whole blood of K₂EDTA tube was then added in scalar amount to autologous heparinised aliquots, to obtained different degrees of K₂EDTA blood volume contamination (0%; 5%; 13%; 29%; 43%). The following clinical chemistry parameters were then measured in centrifuged aliquots: alanine aminotranspherase (ALT), bilirubin (total), calcium, chloride, creatinine, iron, lactate dehydrogenase (LD), lipase, magnesium, phosphate, potassium, sodium.

Results:

A significant variation starting from 5% K₂EDTA contamination was observed for calcium, chloride, iron, LD, magnesium (all decreased) and potassium (increased). The variation of phosphate and sodium (both increased) was significant after 13% and 29% K₂EDTA contamination, respectively. The values of ALT, bilirubin, creatinine and lipase remained unchanged up to 43% K₂EDTA contamination. When variations were compared with desirable quality specifications, the bias was significant for calcium, chloride, LD, magnesium and potassium (from 5% K₂EDTA contamination), sodium, phosphate and iron (from 29% K₂EDTA contamination).

Conclusions:

The concentration of calcium, magnesium, potassium, chloride and LD appears to be dramatically biased by even modest K₂EDTA contamination (i.e., 5%). The values of iron, phosphate, and sodium are still reliable up to 29% K₂EDTA contamination, whereas ALT, bilirubin, creatinine and lipase appear overall less vulnerable towards K₂EDTA contamination.     

几组头骨样本的形态分析和变异性检验

人体测量学常常通过观察和测量人类骨骼等来研究人类生物学特征。本文利用现代形态学的方法研究头骨样本,研究不同人种之间的差异,把每个样本的地标点笛卡尔坐标数据转换为Bookstein坐标数据,然后进行形态统计分析。本文通过正态性检验,协方差阵的齐性检验和总体均值向量的检验,来推断几组头骨样本的形状是否存在显著性差异。     

基于Budyko假设评估洮儿河流域中上游气候变化的径流影响

洮儿河流域中上游为我国东北典型生态敏感地区,近几十年来由于受到人类活动与气候变化的综合影响,一系列生态问题开始凸显。为更好的进行水资源管理,迫切需要准确评估气候变化及人类活动对径流的影响。本文基于Penman-Monteith公式计算研究区及其周边气象站点的潜在蒸散发,采用非参数Mann-Kendall检验及滑动T检验识别径流、降水及潜在蒸散发的趋势及突变点。发现作为整个研究区控制站点,洮南站年径流具有明显上升趋势并以1985年为突变点,据此将研究时段划分为基准期及变化期。然后利用降水及潜在蒸散数据,基于6种Budyko公式评估气候变化对年径流影响,结果表明气候因素约占45%。研究结论证实了人类活动对流域水文过程的确具有显著影响,增进了对该区水文水资源的认识。     

Reduction of gross hemolysis in catheter-drawn blood using Greiner Holdex? tube holder

Introduction:

Blood collection through intravenous lines frequently causes spurious hemolysis. Due to specific structure, the tube holder Holdex^® (Greiner Bio-One GmbH, Kremsmuenster, Austria) is supposed to prevent erythrocyte injury in samples collected from catheters, so that we planned a specific study to support this hypothesis.

Materials and methods:

Blood was collected from emergency department (ED) patients with 20-gauge catheter. In patients with odd order numbers, first and second tubes were collected with conventional holder (BD Vacutainer One Use Holder, Becton Dickinson, Milan, Italy) and the third with Holdex, whereas in even patients first and second tubes were drawn with Holdex and the third using BD Vacutainer One Use Holder. The first tube was discarded, whereas the second and third were centrifuged and serum was tested for potassium, lactate dehydrogenase (LD) and hemolysis index.

Results:

The final study population consisted in 60 ED patients. Concentrations of potassium (4.25 vs. 4.16 mmol/L; P = 0.031), LD (498 vs. 459 U/L; P = 0.039) and cell-free hemoglobin (0.42 vs. 0.22 g/L; P = 0.042) were higher in samples collected with BD Vacutainer One Use Holder than with Holdex. The mean bias of cell-free hemoglobin was −0.4 g/L in samples collected with Holdex. Although the frequency of samples with cell-free hemoglobin > 0.5 g/L was identical (17/60 vs. 17/60; P = 1.00), the frequency of those with concentrations >3.0 g/L was higher using BD Vacutainer One Use Holder than Holdex (4/60 vs. 0/60; P = 0.042).

Conclusions:

The use of Holdex for drawing blood from intravenous lines may be effective for reducing gross hemolysis.     

Avoidance to wipe alcohol before venipuncture is not a source of spurious hemolysis

Background

It is still uncertain whether or not avoidance to let disinfectant alcohol dry at the site of venipuncture is a source of spurious hemolysis when drawing venous blood.

Methods:

In a consecutive series of 52 outpatients referred for routine laboratory testing, venous blood was drawn by direct venipuncture with (odd group) or without (pair group) wiping 70% isopropyl alcohol at the site of venipuncture. A 3.5 mL evacuated tube with clot activator and gel separator was drawn from a vein of the upper limb, serum was immediately separated with standard centrifugation and tested for potassium, lactate dehydrogenase (LD), aspartate aminotransferase (AST) and hemolysis index (HI) on Roche Cobas.

Results:

No specimen was discarded for unsatisfactory venipuncture. No differences for age and gender were observed between groups. As regards the four parameters investigated, no significant differences could be observed between patients in whom blood was drawn with or without letting the alcohol dry. It is also noteworthy that no sample in both groups exceeded the conventional sample rejection threshold of cell-free hemoglobin.

Conclusions:

The results of our prospective, randomized study attest that failure to wipe alcohol at the site of venipuncture should not be considered as a potential source of spurious hemolysis when drawing blood.     

Incorrect order of draw could be mitigate the patient safety: a phlebotomy management case report

Procedures involving phlebotomy are critical for obtaining diagnostic blood specimens and represent a well known and recognized problem, probably among the most important issues in laboratory medicine. The aim of this report is to show spurious hyperkalemia and hypocalcemia due to inadequate phlebotomy procedure. The diagnostic blood specimens were collected from a male outpatient 45 years old, with no clinical complaints. The tubes drawing order were as follows: i) clot activator and gel separator (serum vacuum tube), ii) K₃EDTA, iii) a needleless blood gas dedicated-syringe with 80 I.U. lithium heparin, directly connected to the vacuum tube holder system. The laboratory testing results from serum vacuum tube and dedicated syringe were 4.8 and 8.5 mmol/L for potassium, 2.36 and 1.48 mmol/L for total calcium, respectively. Moreover 0.15 mmol/L of free calcium was observed in dedicated syringe. A new blood collection was performed without K₃EDTA tube. Different results were found for potassium (4.7 and 4.5 mmol/L) and total calcium (2.37 and 2.38 mmol/L) from serum vacuum tube and dedicated syringe, respectively. Also free calcium showed different concentration (1.21 mmol/L) in this new sample when compared with the first blood specimen. Based on this case we do not encourage the laboratory managers training the phlebotomists to insert the dedicated syringes in needle-holder system at the end of all vacuum tubes. To avoid double vein puncture the dedicated syringe for free calcium determination should be inserted immediately after serum tubes before EDTA vacuum tubes.     

Critical review and meta-analysis of spurious hemolysis in blood samples collected from intravenous catheters

Background:

A number of preanalytical activities strongly influence sample quality, especially those related to sample collection. Since blood drawing through intravenous catheters is reported as a potential source of erythrocyte injury, we performed a critical review and meta-analysis about the risk of catheter-related hemolysis.

Materials and methods:

We performed a systematic search on PubMed, Web of Science and Scopus to estimate the risk of spurious hemolysis in blood samples collected from intravenous catheters. A meta-analysis with calculation of Odds ratio (OR) and Relative risk (RR) along with 95% Confidence interval (95% CI) was carried out using random effect mode.

Results:

Fifteen articles including 17 studies were finally selected. The total number of patients was 14,796 in 13 studies assessing catheter and evacuated tubes versus straight needle and evacuated tubes, and 1251 in 4 studies assessing catheter and evacuated tubes versus catheter and manual aspiration. A significant risk of hemolysis was found in studies assessing catheter and evacuated tubes versus straight needle and evacuated tubes (random effect OR 3.4; 95% CI = 2.9–3.9 and random effect RR 1.07; 95% CI = 1.06–1.08), as well as in studies assessing catheter and evacuated tubes versus catheter and manual aspiration of blood (OR 3.7; 95% CI = 2.7–5.1 and RR 1.32; 95% CI = 1.24–1.40).

Conclusions:

Sample collection through intravenous catheters is associated with significant higher risk of spurious hemolysis as compared with standard blood drawn by straight needle, and this risk is further amplified when intravenous catheter are associated with primary evacuated blood tubes as compared with manual aspiration.     

Preanalytical quality improvement – in quality we trust

Background

The preanalytical phase represents the major source of variability in laboratory diagnostics. Our aim was to assess to what extent underfilling of primary blood tubes may impact upon routine coagulation testing.

Materials and methods:

Blood was drawn by syringe from 21 healthy volunteers and 6 patients on warfarin therapy, and immediately transferred into 3.6 mL vacuum tubes containing 3.2% sodium citrate (Terumo Europe N.V., Leuven, Belgium). All tubes were filled using standardized volumes of whole blood to produce scalar amounts of filling: 3.6 mL (i.e., 100%), 3.2 mL (89%), 2.8 mL (78%) and 2.4 mL (67%). Samples were mixed and centrifuged at 1300 × g for 10 min. The plasma was tested for prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen (FBG) on ACL TOP (Instrumentation Laboratory - IL, Milan, Italy), using IL reagents. A polynomial plot was derived for each parameter from interpolation of clotting values obtained with different percentages of filling, and these plots were compared with quality specifications (± 2.0 for PT, ± 2.3 for APTT and ± 4.8 for FBG) to calculate the minimal filling volume required to produce clinically acceptable results.

Results:

The equations were (PF, Percentage of filling): PT (sec) = 3.375 × PF^2–6.255 × PF + 17.806 (r = 0.980); APTT (sec) = 8.925 × PF^2–23.578 × PF + 46.356 (r = 0.979); and FBG (mg/dL) = −311.5 × PF^2 + 422.1 × PF + 147.07 (r = 0.994). According to these equations, the minimum allowed thresholds of blood tubes filling were > 61% for PT, > 87% for APTT and > 71% for FBG.

Conclusions:

Our results confirm that routine coagulation testing performed on underfilled tubes may generate biased and clinically misleading test results. This is particularly critical for APTT, wherein tubes filled at less than ∼90% generate unreliable data. The FBG and the PT seem more resistant to underfilling, clinical significant biases being observed only where blood tubes were filled at less than ∼60 and ∼70%, respectively.     

心率变异性分析及其在体育运动中的应用

心率变异性（ＨｅａｒｔＲａｔｅＶａｒｉａｂｉｌｉｔｙ，ＨＲＶ）分析可帮助判断多种心血管疾病预后，被认为是预测心梗后发生心性猝死危险性的独立而敏感的指标。笔者从ＨＲＶ的生理基础，测定方法，临床和体育运动中的应用几个方面综合评述了这一方法的研究现状。     

论泉州民俗的主要特征

民俗的特征，是民俗学的一个基本理论问题。本文通过对泉州民俗的考察，认为其主要特征表现为传播性、区域性和变异性。