Validating a point of care lactate meter in adult patients with sepsis presenting to the emergency department of a tertiary care hospital of a low- to middle-income country

BACKGROUND: Timely identification of high blood lactate levels in septic patients may allow faster detection of those patients requiring immediate resuscitation. Point-of-care (POC) testing is being increasingly utilized in the emergency department (ED). We examined the accuracy and time-saving effect of a handheld POC lactate device for the measurement of fingertip and whole blood lactate as compared with reference laboratory blood testing in septic ED patients.     

Assuring quality in laboratory testing at the point of care

The science of laboratory medicine has undergone much change during recent years. Despite more recent emphasis on quality improvement, there has not been sufficient attention paid to effective quality management of new approaches to laboratory testing such as point of care testing. It is important that appropriate resources be allocated to quality management, so that waste is minimized and that resources which are expended may be demonstrated to affect the quality of patient care in a positive way. Older quality management tools such as process quality control and proficiency testing are vital to the success of point of care testing programs, however, new ways of looking at the use of these tools are required. Newer approaches such as electronic quality control of point of care devices and an expanded role of total quality management strategies will enhance rather than supplant the more traditional quality improvement mechanisms.     

POCT血糖仪的性能分析

目的比对5个品牌9款床边检测（POCT）血糖仪的主要分析性能。方法用高、中、低3个浓度的质控品在9款POCT血糖仪上进行检测,连续测试30d,计算变异系数（CV）。取高、中、低3种不同葡萄糖浓度的患者样本,同一样本取2份。一份为新鲜全血[乙二胺四乙酸（EDTA）抗凝],在9款POCT血糖仪上进行检测,计算同一样本在9款POCT血糖仪上检测所得结果的均值（x）、标准差（s）、CV;另一份为新鲜血清样本,用日立7060全自动生化分析仪进行检测,评价日立7060全自动生化仪与POCT血糖仪测定结果的相关性。结果质控品在9款POCT血糖仪上所测结果的CV在2．62％～5．86％之间,符合国家对血糖检测系统的测量重复性要求（CV不超过7．5％）。高浓度血糖用POCT血糖仪所测结果的CV在10％左右,中、低浓度血糖用POCT血糖仪所测结果的CV均〉10％,与美国临床实验室标准化委员会（NCCLS）对葡萄糖POCT的管理要求（总误差≤10％）不符。Johnson Ultra和ArkRay GT-1810 2款POCT血糖仪与日立7060全自动生化仪所测结果的相关系数（r）〈0．95,相关性略差;其他几款POCT血糖仪与日立7060全自动生化仪所测结果的r均t〉0．95,相关性较好。KBCT-X10、Roche Integra、Advantage和Johnson Ultra POCT血糖仪的斜率（b）超出1．0±0．05。结论POCT血糖仪仅可用于患者空腹血糖的监测或血糖过筛试验,不能代替实验室血糖的检测结果作为确诊试验。同时在选择POCT血糖仪时,不能仅一味追求其检测的快速,应该对血糖仪的分析性能进行综合评价。     

Quality assurance practices for point of care testing programs: Recommendations by the Canadian society of clinical chemists point of care testing interest group

Point of Care Testing (POCT) refers to clinical laboratory testing performed outside the central laboratory, nearer to the patient and sometimes at the patient bedside. The testing is usually performed by clinical staff, such as physicians or nurses, who are not laboratory trained. This document was developed by the POCT Interest group of the Canadian Society of Clinical Chemists (CSCC) as practical guidance for quality assurance practices related to POCT performed in hospital and outside hospital environments. The aspects of quality assurance addressed in this document include: (1) device selection, (2) initial device verification, (3) ongoing device verification, (4) ongoing quality assurance including reagent and quality control (QC) lot changes, and (5) quality management including operator and document management.     

POCT血糖仪的性能分析

目的比对5个品牌9款床边检测(POCT)血糖仪的主要分析性能。方法用高、中、低3个浓度的质控品在9款POCT血糖仪上进行检测,连续测试30 d,计算变异系数(CV)。取高、中、低3种不同葡萄糖浓度的患者样本,同一样本取2份。一份为新鲜全血[乙二胺四乙酸(EDTA)抗凝],在9款POCT血糖仪上进行检测,计算同一样本在9款POCT血糖仪上检测所得结果的均值(x-)、标准差(s)、CV;另一份为新鲜血清样本,用日立7060全自动生化分析仪进行检测,评价日立7060全自动生化仪与POCT血糖仪测定结果的相关性。结果质控品在9款POCT血糖仪上所测结果的CV在2.62%~5.86%之间,符合国家对血糖检测系统的测量重复性要求(CV不超过7.5%)。高浓度血糖用POCT血糖仪所测结果的CV在10%左右,中、低浓度血糖用POCT血糖仪所测结果的CV均>10%,与美国临床实验室标准化委员会(NCCLS)对葡萄糖POCT的管理要求(总误差≤10%)不符。Johnson Ultra和ArkRay GT-1810 2款POCT血糖仪与日立7060全自动生化仪所测结果的相关系数(r)<0.95,相关性略差;其他几款POCT血糖仪与...     

Base excess and lactate as prognostic indicators for patients admitted to intensive care

Objective: To examine whether values of arterial base excess or lactate taken on admission to a general intensive care unit indicate prognosis, and whether this can be used as a screening tool for future intensive care admissions. Design: Observational study. Setting: University teaching hospital general adult intensive care unit. Patients: 148 consecutive patients admitted to the intensive care unit. Interventions: Arterial blood samples were obtained on admission to the intensive care unit and 24 h following admission. Measurements and results: Arterial base excess and lactate concentrations were measured from the blood samples. Both base excess and arterial lactate samples on admission have good prognostic abilities (area under the curve on receiver operator characteristic analysis of 0.73, 0.78, respectively). The value of base excess on admission with the best predictive ability was a base excess more negative than –4 mmol/l, and the corresponding value for lactate was greater than 1.5 mmol/l. The combination of these two markers on admission to the intensive care unit led to a sensitivity of 80.3 % and a specificity of 58.7 % for mortality. The achievement of this combination was associated with an increased mortality (50.6 % vs. 15 %, p < 0.0001), older age (70 vs. 61.5 years, p < 0.05), a greater requirement for inotropic support (30.9 % vs. 4.5 %, p < 0.0001) and higher organ failure scores both on admission and for the subsequent 24 h. Conclusions: Both base excess and lactate, or the combination of the two, can be used to predict outcome in patients admitted to the intensive care unit. These variables could be utilized to identify patients who have a high risk for mortality and thus who should be admitted to the intensive care unit. Received: 18 April 2000 Final revision received: 15 May 2000 Accepted: 15 May 2000     

Point of care testing in the emergency department

Point of care (POC) testing in the Emergency Department (ED) is becoming more common. The implementation and maintenance of POC testing in the ED, however, is a complex issue. We performed a systematic review of the English language literature published between 1985 and June 2001 with a focus on POC testing and ED application. Articles that addressed the following were included in the review: implementation of POC testing, maintenance and regulation of POC testing, and application of POC testing. Current POC technology has been found to be reliable in various patient care settings, including the ED. Cost and connectivity issues are complex and difficult to assess, making these the greatest barriers to the full acceptance of POC testing in the ED. Patient care issues must be weighed against the cost of implementing POC testing and supporting the infrastructure needed to maintain this technology in the ED.     

21台床旁检验血糖仪与生化分析仪血糖检测结果比对

目的定期监测新疆医科大学第一附属医院21台床旁检验血糖仪（以下简称POCT血糖仪）检测结果与贝克曼生化分析仪血糖测定结果的一致性,全面了解医院血糖测定值之间的差异。方法挑选10例空腹血糖在3.76～19.84mmol/L（生化分析仪血糖检测结果）的患者,分别抽取乙二胺四乙酸（EDTA）抗凝全血和未抗凝血。EDTA抗凝血在POCT血糖仪测定血糖;不抗凝血在贝克曼DXC800生化分析仪测定血糖,每份标本测定3次,取均值。对合格的19台仪器按使用年限编号排序,随机抽样5台,用新疆维吾尔自治区临床检验中心POCT血糖室间质评物测定血糖,与靶值比对,计算偏倚。结果 POCT血糖仪测定结果与生化分析仪测定结果比对,19台偏倚在0.93%～11.49%范围,2台仪器测定值偏倚大于20%,19台POCT血糖仪测定值变异系数（CV%）为3.14%～10.82%。抽样的5台POCT血糖仪与新疆维吾尔自治区临床检验中心POCT血糖室间质评靶值（以下简称＂靶值＂）的偏倚为0%～6.87%。结论 21台POCT血糖仪中19台与生化分析仪血糖检测结果比对具有一致性,2台比对差异大。生化分析仪比POCT血糖仪检测结果偏高约0.94%～12.98%。抽样的5台POCT血糖仪与靶值之间的偏倚符合新疆维吾尔自治区临床检验中心质评判定标准。     

Ultrasonic measurement of fetal blood velocity wave form as a secondary diagnostic test in screening for intrauterine growth retardation

Based on routine fetometry screening at 32 weeks of gestation, 80 out of 3226 singleton pregnancies were suspected of intrauterine growth retardation (IUGR) and 72 of them were subjected to repeated fetal blood flow measurements by Doppler ultrasound for evaluation of the fetal condition. The maximum blood velocity wave form recorded from the fetal descending aorta and umbilical artery was classified as normal or abnormal depending on the presence or absence of positive end-diastolic blood flow. Compared to the pregnancies with normal fetal blood flow, the group of 30 pregnancies with abnormal blood flow patterns had significantly more pregnancy complications and more operative deliveries for fetal distress. In the latter group, all newborns but one were small-for-gestational age and had low 1-min Apgar scores more frequently. Fetal blood flow measurements have a good capacity for predicting unfavorable fetal outcomes and can be recommended for clinical use. The combination of ultrasound screening and Doppler blood flow measurement has reduced the number of pregnancies requiring intensive surveillance.     

Utility of common bile duct measurement in ED point of care ultrasound: A prospective study

Background

Measurement of the common bile duct (CBD) is considered a fundamental component of biliary point-of-care ultrasound (POCUS), but can be technically challenging.

Comparison of 3 different multianalyte point-of-care devices during clinical routine on a medical intensive care unit

Purpose

Multianalyte point-of-care (POC) devices are important to guide clinical decisions in critical care. However, the use of different devices in one hospital might cause problems. Therefore, we evaluated 3 commonly used POC devices and analyzed accuracy, reliability, and bias.

Methods

Seventy-four arterial blood samples were analyzed by 3 POC devices (Cobas, Roche Diagnostics, Mannheim, Germany; ABL800 Flex, Radiometer GmbH, Germany; Gem Premiere, Instrumentation Laboratory, Germany). For selected parameters, samples were also analyzed in the central laboratory. pCO2, pO2, SO2, bicarbonate and standard bicarbonate, sodium, potassium, calcium, pH, lactate, base excess (BE[B] and BEecf), glucose, hemoglobin, and hematocrit were compared.

Results

For most parameters, only minor, although statistically significant, changes were observed between the POC devices. For pO2, BE(B), hemoglobin, and hematocrit, clinically significant differences were found.

Conclusion

Although POC devices are of high standard and overall comparability between devices is high, there might be a clinically relevant bias between devices, as found in our study for pO2, BE(B), hemoglobin, and hematocrit. This can be of importance when interpreting results of the same patient obtained from different POC devices, as it could happen when a patient is transferred within a hospital where different devices are used.     

Lactate measurements in critically ill patients with a hand-held analyser

Objective: To compare a recently introduced hand-held lactate analyser to a reference point of care analyser (POCI) and the hospital laboratory in a critical care setting. Setting: 10-bed surgical/medical intensive care unit in a teaching hospital. Patients and methods: In 39 critically ill patients, 50 convenience measurement cycles consisting of three paired measurements at 30-min intervals were carried out with a hand-held analyser, reference POCI and hospital laboratory using arterial blood samples. Duplicate measurements with the hand-held analyser were done in 129 blood samples. Results: Lactate levels ranged from 1.1 to 21.0 mmol/l. Regression analysis of the hand-held analyser and laboratory showed a slope of 1.01, bias of –0.38 mmol/l, R ² = 0.97 and mean error of 14.9 %. Reference POCI versus laboratory: slope = 1.07, bias = –0.29 mmol/l, R ² = 0.98 and mean error of 6.4 %. Hand-held analyser versus reference POCI: slope = 0.90, bias = 0.09 mmol/l and R ² = 0.92. The hand-held analyser showed acceptable precision. Conclusion: The hand-held lactate analyser can reliably measure arterial blood lactate levels in critically ill patients. Received: 19 January 1999 Accepted: 18 June 1999     

Comparison of three methods for detection of the lactate threshold

The lactate threshold (LT) represents the onset of a metabolic acidosis during graded exercise testing (GXT). It is a valuable measurement in clinical exercise testing and correlates well with endurance performance. Our purpose was to compare three LT detection methods, namely, Inspection (work rate at onset of a systematic increase in blood lactate concentration determined by inspection of blood lactate versus work rate plot), 0.5 mM (work rate which just precedes a rise in blood lactate concentration of >0.5 mM) and log-log (work rate at the intersection of two linear lines in plot of log lactate versus log work rate where the residual sum of squares for both lines added together is minimized). Fourteen subjects underwent cycle ergometer GXT with blood samples obtained at the end of each 3-min work rate increment and analysed for lactate concentration. The mean +/- 95% confidence limits of work rates at LT for the Inspection, 0.5 mM and log-log methods were 104.5 +/- 28.0, 103.2 +/- 28.1 and 105.1 +/- 27.3 W, respectively. Repeated-measures analysis of variance yielded a non-significant F ratio. The Bland-Altman bias +/- 95% limits of agreement for Inspection versus 0.5 mM, Inspection versus log-log and 0.5 mM versus log-log were 1.3 +/- 20.6, -0.6 +/- 12.5 and -1.9 +/- 20.5 W, respectively. The intraclass correlation coefficients for Inspection versus 0.5 mM, Inspection versus log-log and 0.5 mM versus log-log were 0.978, 0.992 and 0.977, respectively. The results of this study suggest that all three methods detect the LT at the same work rate.     

2种血糖仪检测方法与生化仪血糖检测的比对

目的对2种血糖仪检测方法与生化仪血糖检测进行比对,对结果、临床可操作性及影响因素进行评估。方法选取糖尿病和非糖尿病患者共61例,早晨抽取空腹静脉血2mL置于含有EDTA-K2的抗凝管中颠倒混匀。取1滴静脉血用血糖仪测静脉全血血糖(VBG),剩余标本离心取血浆用生化仪(日立7600)检测静脉血浆葡萄糖浓度(VPG)。抽取静脉血后5min内用同一血糖仪检测指尖毛细血管血糖(CBG)。以VPG为参考标准,分别计算血糖仪VBG和CBG的偏差;用统计软件分别进行VBG或CBG与VPG的相关性分析;针对VBG和CBG绘制Parkes误差网格图,判断数据的临床接受程度。结果使用罗氏公司的Accu-Chek Performa血糖仪检测静脉血糖或毛细血管血糖与生化方法血糖比对,结果呈线性相关(r分别为0.991和0.989),偏差范围均能达到国家标准,所有数据在临床可接受区。结论便携式血糖仪检测静脉血糖与生化血糖结果比对,因标本来源一致、操作流程简单、可人为制造过高或过低血糖样本,故建议医疗机构采用该方案进行定期比对实验。     

Analytical performance of three point of care methods for pleural fluid pH analysis

Objective

The performance of three point of care methods for pleural fluid pH analysis was compared to a currently validated blood gas analyzer.

Design and methods

An ABL 725 (Radiometer America, Westlake, OH) was used as the reference method to evaluate three cartridge-based assays: ABL 90 FLEX (Radiometer), and i-STAT 1 (Abbott Point of Care, Abbott Park, IL) CG4 + and G3 + cartridges for pleural fluid pH analysis. Pooled residual pleural fluid samples and quality control material were analyzed to determine intra- and inter-assay precision. Method comparison was performed with spiked (n = 40) and clinically-ordered (n = 10) pleural fluid samples across the analytical measuring range.

Results

All methods demonstrated inter-assay CVs < 0.1% at pH values of 7.1 and 7.6, and intra-assay CVs < 0.3% at pH values of 7.2 and 7.7. Bland–Altman plots demonstrated clinically significant bias between ABL 725 and each cartridge-based method only at pH > 7.6. For samples with pH < 7.6 mean bias vs. ABL 725 was − 0.01 for ABL 90 FLEX and 0.03 for i-STAT 1 CG4 + and G3 + cartridges. Clinical concordance using a decision limit of pH 7.2 was 96–98% for the three methods.

Conclusions

Analytical and clinical performance of the three cartridge-based methods was comparable to a validated blood gas analyzer for pleural fluid pH analysis. Cartridge-based pH methods offer the advantage of easier troubleshooting for clots and clogs as they use disposable electrodes. However cartridge-based methods are not currently FDA-approved for pleural fluid samples, such that additional validation would be required for this specimen type.     

The time-distance recorder as a means of improving the accuracy of fetal blood flow measurements

The influence of pulsatile diameter changes on calculation of volume flow has been studied. In vitro studies and an animal study were carried out with a real-time imaging and pulsed Doppler velocity measurement system. For precise pulsatile diameter information a wall motion tracking device was incorporated. Whereas in vitro a high degree of accuracy was found for the measurements of volume flow, this could not be substantiated in the descending aorta of the fetal lamb, in which Doppler volume flow differed between -7.5 and 17% from magnetic volume flow. In a clinical study the relative influence of various diameter approximations on calculated fetal aortic volume flow was assessed in 16 normal third trimester pregnancies. Depending on the selected diameter approximation method it appeared that differences from 19% underestimation to 9% overestimation in calculated volume flow could be obtained when reference was made to volume flow derived from diameter and velocity information.     

重症监护室常用血糖测量方法的一致性研究

目的 评价目前重症监护室(intensive care unit,ICU)常用的4种血糖测量方法与静脉血/血生化仪法的一致性,并分析可能的影响因素.方法 前瞻性序贯纳入2007年11月至2008年1月期间收入北京协和医院内科ICU病房且预期ICU住院时间＞48 h的患者49例,共检测血糖130组,每组均采用毛细血管血/血糖仪法、动脉血/血糖仪法、动脉血/血气分析仪法和动脉血/血生化仪法测量血糖,分别计算上述4种方法与静脉血/血生化仪法(标准法)所测血糖值的差值、相关系数、偏倚校正因子及不一致率,并采用Logistic回归分析影响一致性的因素.结果 毛细血管血/血糖仪法、动脉血/血糖仪法、动脉血/血气分析仪法、动脉血/血生化仪法所测血糖值与标准法所测血糖值的差值分别为:(1.7±1.4)mmol/L,(1.6±1.4)mmol/L,(1.1±1.2)mmol/L,(0.5±1.2)mmol/L,不一致率分别为66.9%,63.8%,40.0%,23.8%.相关系数分别为0.844,0.845,0.895和0.896,偏倚校正因子分别为0.821,0.831,0.914和0.979.红细胞比积减低是毛细血管血/血糖仪法(OR=0.923,P=0.03)和动脉血/血糖仪法(OR=0.921,P=0.014)血糖测量值与标准法不一致的独立危险因素.结论 在重症监护病房,采用血糖仪测量血糖的方法与标准法的一致性均较差,而血气分析仪法则是一致性较好的床旁血糖检测方法.红细胞比积减低可影响血糖仪测量的准确性.

Abstract：

Objective To evaluate the accuracy of five blood glucose measurements commonly used in ICU and to determine the potential factors interfering the accuracy. Method This prospective study carried out in consecutively enrolled 49 patients stayed more than 48 hours in the medical ICU of Peking Union Medical College Hospital from November 2007 to January 2008. A total of 130 blood samples were measured to determine blood glucose with five different methods, and the biochemistry analyzer in central laboratory was regarded as reference method for comparison with other four methods, ( 1 ) capillary blood/glucometer;(2) arterial blood/glucometer; (3) arterial blood/blood gas analyzer; and (4) arterial blood/biochemistry analyzer. The accuracy of a method tested was judged by the difference in level of blood glucose between it and reference method, correlation coefficient, bias correction factor and discrepancy. The independent factors for the discrepancies were identified by multivariate logistic regression. Results The values of differences in level of blood glucose between above four methods and the reference were ( 1.7 ± 1.4) mmol/L,( 1.6 ± 1.4 ) mmol/L, ( 1.1 ± 1.2) mmol/L, and (0.5 ± 1.2 ) mmol/L, respectively. The rates of discrepancy were 66.9%, 63.8%, 40.0% and 23.8%. The correlation coefficients were 0. 844, 0. 845, 0. 895and 0. 896. The bias correction factors were 0. 821,0.831,0.914 and 0. 979. Decrease in hematocrit was statistically associated with the discrepancy between glucometer analysis methods and the reference, with OR of 0.923 for capillary blood ( P = 0.03 ) and 0. 912 for arterial blood( P = 0.014), respectively. Conclusions Glucometer analysis poorly correlated with reference method and blood gas analysis in ICU patients. Decrease in hematocrit significantly increased the degree of discrepancy in glucose measurements between glucometer analysis and the reference.