International Organization For Standardization Criteria Research Articles

Evaluation of several routine methods for fosfomycin and mecillinam susceptibility testing of Enterobacterales urine isolates.

Performance evaluation of routine laboratory methods to determine the susceptibility of Enterobacterales urinary isolates to fosfomycin (oral administration) and mecillinam. We collected 347 Enterobacterales isolates from monomicrobial midstream urine samples from women with significant bacteriuria and leukocyturia. Mostly non-Escherichia coli isolates (i.e. Klebsiella spp., Citrobacter koseri, Enterobacter cloacae complex and Proteus mirabilis) were included (n = 298). Performance of VITEK®2, ETEST®, and disc diffusion to determine fosfomycin and mecillinam susceptibility was evaluated following International Organization for Standardization (ISO) 20776-2:2021 (or 20776-2:2007 for disc diffusion) in comparison with the agar dilution reference method. For fosfomycin testing, VITEK®2 and ETEST® were close to reaching ISO requirements (essential agreement ≥ 90%; bias ±30%) for C. koseri, E. coli and P. mirabilis. Categorical agreement (CA) and major error rates were acceptable for disc diffusion. Fosfomycin displayed lower activity against E. cloacae complex and Klebsiella spp., with MIC50 (minimum inhibitory concentration required to inhibit the growth of 50% of tested isolates) equal to the E. coli EUCAST breakpoint (8 mg/L). For these species, the three alternative techniques overestimated MICs and resistance, and did not meet performance criteria. For mecillinam testing of Enterobacterales isolates, apart from P. mirabilis, ETEST® nearly fulfilled ISO requirements, and CA rates were acceptable for disc diffusion. ISO criteria were reached for C. koseri and E. coli testing with VITEK®2, apart from too high rates of very major errors. For P. mirabilis, performances were unacceptable, whatever the routine method used. Commercially available tests may serve as alternatives to agar dilution to assess fosfomycin (oral) and mecillinam susceptibility of Enterobacterales urinary isolates, with important interspecies variabilities. Additional studies comprising more fosfomycin- and mecillinam-resistant isolates are needed to strengthen our conclusions.

Validating the Accuracy of Omron HEM-1026 (HCR-1901T2/HCR-1902T2): Blood Pressure Monitoring Device at Home, According to the Universal Protocol.

The performance of Omron HEM-1026 (HCR-1901T2 / HCR-1902T2) for monitoring blood pressure (BP) in the upper arm was validated in accordance with the International Organization for Standardization (ISO) 81060-2:2018+amendment (Amd)1:2020 protocol. The device was assessed in 101 participants who fulfilled the inclusion criteria, including arm circumference range and systolic and diastolic BP provided by the protocol. Data validation and analysis were performed according to the manufacturer's instructions. In the ISO 81060-2:2018+Amd 1:2020 validation procedure (criterion 1), the mean ± standard deviation (SD) of the differences between the test device and reference BP was -2.1 ± 7.24/-0.6 ± 5.63 mmHg (systolic/diastolic). These data fulfilled the ISO81060-2:2018+Amd1:2020 requirement of ≤5±≤8 mmHg. The mean differences between the two observers and Omron HEM-1026 were -2.1 ± 5.71 mmHg for systolic BP and -0.6 ± 4.81 mmHg for diastolic BP, fulfilling criterion 2 with an SD of ≤ 6.62 for systolic BP and ≤ 6.91 for diastolic BP. The two ISO criteria were fulfilled. The Omron HEM-1026 BP monitor fulfilled the requirements of the ISO 81060-2:2018+Amd 1:2020 validation standard and can be recommended for home BP measurements in the general population.

Validating the accuracy of Omron HEM-7372T1-AZAZ (BP5460) in monitoring blood pressure according to the ISO 81060-2:2018+Amd 1:2020 protocol in the general population.

The performance of the Omron HEM-7372T1-AZAZ (BP5460) in monitoring blood pressure (BP) in the upper arm was validated in accordance with the International Organization for Standardization (ISO) 81060-2:2018 (E) and amendment (Amd)1:2020 protocol. The device was used to assess 98 participants who fulfilled the inclusion criteria, including the range of arm circumference and systolic and diastolic BP, in accordance with the protocol. Data validation and analysis were performed according to the manufacturer's instructions. In the ISO validation procedure (criterion 1), the mean ± SD of the differences between test device readings and reference BP was 0.3 ± 6.17/3.6 ± 5.26 mmHg (systolic/diastolic). These data fulfilled the ISO requirements of ≤5±≤8 mmHg. The mean differences between the observer measurements and Omron HEM-7372T1-AZAZ (BP5460) readings were 0.3 ± 4.82 mmHg for systolic BP and 3.6 ± 4.78 mmHg for diastolic BP, fulfilling criterion 2 with SD values of ≤6.95 for SBP and ≤5.89 for DBP. Therefore, two ISO criteria were fulfilled. The Omron HEM-7372T1-AZAZ BP monitor fulfilled the requirements of the ISO validation standard. This device can be recommended for home BP measurements in the general population.

Comparison of an intermittently scanned (flash) continuous glucose monitoring system to standard self-monitoring of capillary blood glucose in gestational diabetes mellitus.

Objective Gestational diabetes mellitus (GDM) requires close surveillance of blood glucose to prevent perinatal morbidity. Self-monitoring of capillary blood glucose (BGM) comes with considerable psychosocial burden. Intermittently scanned CGM (isCGM) devices are discreet and could considerably impact the lifestyle of the patient. They are designed to replace BGM testing in nonpregnant patients. Data on this technology in pregnancy is scant. The aim of this study was to assess concordance of BGM with isCGM in GDM. Methods IRB approved prospective single arm study evaluating agreement of isCGM (Freestyle Libre 14 day system) compared to BGM when determining glucose levels fasting and 2 hours postprandial for 14 days. This was documented as percentage of results within Zone A (clinically accurate measurements with no effect on clinical action) or Zone B (values that deviate from reference by >20% but would lead to benign/no treatment) of the Parkes Error Grid (developed for non-pregnant patients with diabetes). Per International Organization for Standardization (ISO) criteria, agreement was defined as >95% within Zone A or B. Analytical agreement was evaluated using mean and median absolute relative difference (ARD), mean and median absolute difference (AD). Results There were 1604 pairs of BGM/isCGM observations for 41 patients. Mean glucose values were 102.0 (SD 20.5) mg/dL and 89.4 (SD 20.1) mg/dL for BGM and isCGM, respectively. Mean and median AD were 15.9 and 13.0 mg/dL, respectively. Mean and median ARD were 15.9% and 12.5%, respectively. Zones A and B contained 76.9% and 22.9% of values, respectively, in the Parkes Error Grid, for a total of 99.8%. Conclusions BGM and isCGM demonstrate clinical agreement. However, glucose values with isCGM trended lower, with greater mean and median ARD than prior studies. Given the strict glycemic control required during pregnancy, physicians should be aware of these differences and their possible clinical implications.

An Evaluation of a Language Processor for an African Native Language-based Programming Language

Abstract The design and prototype implementation of a subset of an African indigenous language-based programming language has been carried out and reported. In this study, an evaluation of the processor developed for the native language-based programming language was carried out in order to assess its level of conformance to the characteristics required of a good software product as set by the international organization for standardization (ISO). The developed language processor was evaluated using some metrics for evaluating the quality of software systems including structural and time complexity. A usability test was also conducted to assess users’ perception of the system concerning its relevance and ease of use. The result of system evaluation indicated that the system contains 1558 lines of code, its cyclomatic complexity is 14 and its asymptotic time complexity is of order big oh O (n3), where n is the size of the input to the system. Over 86% of the participants in the usability test attested to the system’s relevance while the usability rating was 86%. The developed system can be inferred to be of good quality as the results of its evaluation are positively on the high side for satisfying most of the ISO criteria for adjudging a software product as being of good quality. Furthermore, the high usability rating for the system indicates that the programming language whose compiler was evaluated satisfies most of the criteria set by the Department of Defense (DOD) for assessing the ‘goodness’ or otherwise of a programming language.

Accuracy of Two CE-Marked Blood Glucose Monitoring System Based on EN ISO 15197:2015

Blood glucose monitoring systems (BGMS) are essential for the management of diabetic patients. Although International Organization for Standardization (ISO) 15197:2015 criteria require rigorous monitoring of BGMS devices before commercialization, manufacturing quality standards may decline after FDA or EU approval. This work aimed to demonstrate the accuracy and precision of two BGMS devices currently available on the market. A laboratory study was conducted from June to August 2021 using two BGMS devices. One hundred samples were collected and evaluated according to ISO 15197:2015 guidelines. Over 95% accuracy was achieved by both devices using stricter ISO criteria (at least 95% of values within ±10 mg/dL or ±10% of the results of the reference measurement procedure). Analysis of the error grid showed that 99.5% of the results were in zone A. Surveillance of the accuracy and precision of BGMS devices after FDA and EU approval is an essential procedure to help patients and physicians manage glycemia and determine an appropriate outcome and personalized approach to diabetes treatment.

The physical properties and anticariogenic effect of experimental resin cement containing ursolic acid.

The aim was to evaluate the physical properties and anti-bacterial activity of resin cement containing ursolic acid (UA) and determine the optimal concentration of UA. Five types of experimental resin cement were prepared according to UA concentration (0, 0.1, 0.5, 1.0, and 2.0 wt%). Flexural strength, film thickness and in vitro cytotoxicity were measured to confirm whether the resin was appropriate under International Organization for Standardization (ISO) criteria. Fifty extracted human molars were prepared, and indirect resin inlays were cemented with experimental resins. Acid-resistant nail varnish was applied, except for the 2-mm area around the restoration. Artificial caries were induced for 6 days through Streptococcus (S.) mutans (ATCC25175). Quantitative light-induced fluorescence (QLF) was used to evaluate the caries progression. One-way analysis of variance (ANOVA) followed by the Dunnett correction were used to statistically analyze the data. In all groups, the physical property of flexural strength, film thickness, and cytotoxicity were satisfied for ISO criteria (p > 0.05). On ∆F (-%) and ∆Q (-%⋅Px) values as QLF parameters, there was a tendency of being lower in groups of resin cement containing higher concentration of UA. Resin cement containing UA of greater than or equal to 0.5% significantly inhibited caries in the area around restoration (p < 0.05). There was no difference between the groups containing UA of greater than or equal to 0.5%. Resin cement containing 0.5% or more UA showed anti-carious effect in the limited range of 2% and satisfied the ISO criteria for flexural strength, film thickness and cytotoxicity.

Accuracy and User Performance of a New Blood Glucose Monitoring System.

Self-monitoring of blood glucose (BG) is important in diabetes management, allowing people with diabetes (PWD) to assess responses to diabetes therapy and to inform if they are attaining their glycemic targets. This study assessed the accuracy and user performance (UP) of a new blood glucose monitoring system (BGMS), CONTOUR®PLUS ELITE, according to International Organization for Standardization (ISO) 15197:2013 criteria and also more stringent criteria. In laboratory Study 1, capillary fingertip blood samples from 100 PWD were evaluated using the new BGMS. In clinical Study 2, 130 PWD had Yellow Springs Instrument (YSI) analyzer reference measurements against subject-obtained fingertip and palm blood, and trial staff-obtained venous blood. The new BGMS was tested with test strips from three different lots. A UP questionnaire assessed ease of use. Study 1: 100% of combined accuracy results fulfilled ISO criteria (±15 mg/dL at BG <100 mg/dL; ±15% at BG ≥100 mg/dL); 99.8% fulfilled more stringent criteria (±10 mg/dL at BG <100 mg/dL; ±10% at BG ≥100 mg/dL). Error grid analysis showed that 100% of results were within zone A. Study 2: >98% of subject- and 100% of trial staff-obtained performance results met ISO criteria. Most subjects (>96%) found the BGMS easy to use. The new BGMS exceeded minimum ISO 15197:2013-specified standards for both accuracy and UP criteria, along with the more stringent accuracy criteria. These data show that this new BGMS can be a useful tool in managing glycemic control for PWD.

In vitro and in vivo evaluation of the safety and efficacy of a novel liquid fiducial marker for image-guided radiotherapy.

The true extent of a tumor is difficult to visualize, during radiotherapy, using current modalities. In the present study, the safety and feasibility of a mixture of N-butyl cyanoacrylate and lipiodol (NBCA/Lip) was evaluated in order to investigate the optimal combination for application as a fiducial marker for radiotherapy. Four combinations of NBCA/Lip injection (1:1–0.1, 1:1–0.15, 1:3–0.1 and 1:3–0.15 ml) were injected into the subcutaneous tissue of BALB/c mice. The changes in gross histopathology, body weight, skin score, marker volume, neutrophil and macrophage counts were observed to analyze the effects of the different mixing ratios and injection volumes, in order to identify the best combination. Evaluation according to the International Organization for Standardization criteria was further conducted in order to test the biocompatibility of the mixture, including an acute systematic assay with mice, cytotoxicity with L929 fibroblasts and delayed-type hypersensitivity tests with guinea pigs and an intradermal test with rabbits. The results revealed that at the seventh week, 42 markers (42/48; 87.5%) were still visible using computed tomography (CT) imaging. No serious adverse effects were observed throughout the study period; however, the combination of 1:1–0.1 ml had the lowest body weight and worst skin score. A review of the histopathological reaction to NBCA/Lip revealed a combination of acute inflammation, chronic inflammation, granulation tissue, foreign-body reaction and fibrous capsule formation. The 1:1 NBCA combination ratio resulted in the most intense tissue repair reaction and a slower degradation rate of markers. In general, the combination of 1:3–0.15 ml had a better fusion with local tissue, maintained a stable imaging nodule on CT images for 7 weeks and the final biocompatibility test demonstrated its safety. Overall, the findings of the present study demonstrated NBCA/Lip as a safe and feasible fiducial marker, when using the 1:3–0.15 ml combination.

Assessment of factors that determine the mean absolute relative difference in flash glucose monitoring with reference to plasma glucose levels in Japanese subjects without diabetes

The Abbott FreeStyle Libre flash glucose monitoring system (FGM) is a recently introduced, but widespread continuous glucose monitoring system. While its mean absolute relative difference (MARD) value indicating its accuracy is acceptable with reference to the self-monitoring of blood glucose (SMBG) levels, few reports have examined the MARD in sensor glucose values of FGM (FGM-SG) with reference to plasma glucose (PG) levels and the factors determining it. We performed oral glucose tolerance tests (OGTTs) in 25 Japanese subjects without diabetes. Parkes error grid analyses showed that FGM-SG with either SMBG or PG levels as a reference met International Organization for Standardization criteria. The MARD in FGM-SG with reference to SMBG levels was 10.9 ± 4.1% during OGTTs. Surprisingly, the MARD in FGM-SG with reference to PG levels was 20.3 ± 10.3% during OGTTs, revealing a discrepancy in the accuracy of FGM-SG compared with that of PG levels; moreover, the MARD showed negative correlations with fasting blood sugar level, homeostasis model assessment insulin resistance index, and body mass index (BMI). Multiple regression analyses revealed that BMI contributed the most to the MARD when FGM-SG and PG level were compared, as lean individuals have a greater MARD regardless of glucose levels. Inaccurate FGM data could potentially increase the risk of inappropriate treatment; consideration of such factors is critical to ensure reliable FGM values.

Non-invasive blood pressure monitoring with an oscillometric brachial cuff: impact of arrhythmia.

Arrhythmia-induced beat-to-beat variability of blood pressure (BP) is deemed to hinder the reliability of non-invasive oscillometric measurements (NIBP) but few data support this belief. We assessed the impact of arrhythmia on a NIBP device never tested for this purpose. We compared, in intensive care unit patients with and without arrhythmia, the agreement between three pairs of NIBP (Infinity™ Delta monitor, Dräger medical systems) and invasive readings. For systolic, diastolic and mean BP, the mean bias between NIBP and invasive measurements was not higher, in 89 patients with arrhythmia, than that observed in 127 patients with regular rhythm (p = 0.93 for mean BP). Averaging three measurements overcame the higher within-subject variability of NIBP measurements during arrhythmia, and yielded similar agreement between the two techniques in patients with arrhythmia and with regular rhythm. The international organization for standardization criteria (mean bias < 5 and SD < 8mmHg) were satisfied neither during arrhythmia nor during regular rhythm: for mean BP, mean bias of - 8.0 ± 6.5 and - 7.5 ± 6.1mmHg, respectively. The detection of hypotension (systolic invasive BP < 90mmHg or mean invasive BP < 65mmHg) or hypertension (systolic invasive BP > 140mmHg) by NIBP was similar during arrhythmia and regular rhythm [areas under the receiver operating characteristic curves (AUCROC) of 0.88-0.92, p > 0.13]. The detection of a 10% increase in mean invasive BP after cardiovascular intervention was also associated with similar AUCROCs between the two groups. Provided that triplicates are averaged, the agreement between NIBP measured with the tested device and invasive measurements was not worse during arrhythmia than during regular rhythm.

The CNAP™ Finger Cuff for Noninvasive Beat-To-Beat Monitoring of Arterial Blood Pressure: An Evaluation in Intensive Care Unit Patients and a Comparison with 2 Intermittent Devices

Continuous and intermittent noninvasive measurements of arterial blood pressure (BP) have not been compared in the same population. In a large panel of intensive care unit patients, we assessed the agreement between CNAP™ (Continuous Noninvasive Arterial Pressure) finger cuff beat-to-beat monitoring of BP and reference intraarterial measurements. Two automated oscillometric brachial cuff devices were also tested: CNAP brachial cuff (used for CNAP finger cuff calibration) and an alternative device. The performance for detecting hypotension (intraarterial mean BP <65 mm Hg or systolic BP <90 mm Hg), response to therapy (therapy-induced increase in mean BP >10%), and hypertension (intraarterial systolic BP >140 mm Hg) was evaluated. We also assessed the between-calibration drift of CNAP finger cuff BP in specific situations: cardiovascular intervention or no intervention. With each device, 3 pairs of noninvasive and intraarterial measurements were prospectively collected and analyzed according to current guidelines, the International Organization for Standardization (ISO) standard. The trending ability and drift of the CNAP finger cuff BP were assessed over a 15-minute observation period. In 182 patients, CNAP finger cuff and CNAP brachial cuff readings did not conform to ISO standard requirements (mean bias ± SD exceeding the maximum tolerated 5 ± 8 mm Hg), whereas the alternative automated brachial cuff succeeded for mean and diastolic BP. CNAP finger cuff trending ability was poor (concordance rate <70% over a 15-minute period) owing to a significant drift since calibration, especially if a cardiovascular intervention was performed (n = 75, -7.5 ± 10.2 mm Hg at the 14th minute, ie, before recalibration, versus -2.9 ± 7.9 mm Hg if no cardiovascular intervention occurred, n = 103, P = 0.0008). However, a similar and reliable performance was observed for the detection of hypotension with the CNAP finger cuff (within 4 minutes after calibration) and with the 2 automated brachial cuffs (area under the receiver operating characteristic curve ≥0.91, positive and negative likelihood ratios ≥5 and ≤0.20, respectively). The performance for the detection of response to therapy or of hypertension was slightly lower. In a large population of intensive care unit patients, CNAP did not fulfill the ISO criteria and exhibited a relevant between-calibration drift. However, CNAP measurements collected within 4 minutes after calibration were reliable for detecting hypotension, as were oscillometric devices, while providing beat-to-beat measurements. Interestingly, an alternative automated brachial cuff was more reliable than the native one, used for calibration. This information is important to clinicians using those devices and for further development of the CNAP technology.

Accuracy of Continuous Glucose Monitoring During Three Closed-Loop Home Studies Under Free-Living Conditions.

Objectives: Closed-loop (CL) systems modulate insulin delivery based on glucose levels measured by a continuous glucose monitor (CGM). Accuracy of the CGM affects CL performance and safety. We evaluated the accuracy of the Freestyle Navigator® II CGM (Abbott Diabetes Care, Alameda, CA) during three unsupervised, randomized, open-label, crossover home CL studies.Materials and Methods: Paired CGM and capillary glucose values (10,597 pairs) were collected from 57 participants with type 1 diabetes (41 adults [mean±SD age, 39±12 years; mean±SD hemoglobin A1c, 7.9±0.8%] recruited at five centers and 16 adolescents [mean±SD age, 15.6±3.6 years; mean±SD hemoglobin A1c, 8.1±0.8%] recruited at two centers). Numerical accuracy was assessed by absolute relative difference (ARD) and International Organization for Standardization (ISO) 15197:2013 15/15% limits, and clinical accuracy was assessed by Clarke error grid analysis.Results: Total duration of sensor use was 2,002 days (48,052 h). Overall sensor accuracy for the capillary glucose range (1.1–27.8 mmol/L) showed mean±SD and median (interquartile range) ARD of 14.2±15.5% and 10.0% (4.5%, 18.4%), respectively. Lowest mean ARD was observed in the hyperglycemic range (9.8±8.8%). Over 95% of pairs were in combined Clarke error grid Zones A and B (A, 80.1%, B, 16.2%). Overall, 70.0% of the sensor readings satisfied ISO criteria. Mean ARD was consistent (12.3%; 95% of the values fall within ±3.7%) and not different between participants (P=0.06) within the euglycemic and hyperglycemic range, when CL is actively modulating insulin delivery.Conclusions: Consistent accuracy of the CGM within the euglycemic–hyperglycemic range using the Freestyle Navigator II was observed and supports its use in home CL studies. Our results may contribute toward establishing normative CGM performance criteria for unsupervised home use of CL.

Accuracy of a Simplified Glucose Measurement Device--The HemoCue Glucose 201RT.

Easily available, accurate glucose recordings are important when screening for and managing people with diabetes. The photometric HemoCue(®) (Ängelholm, Sweden) Glucose 201+ system, which delivers lab-comparable glucose recordings, has the drawback that its microcuvettes must be delivered and stored at 4-8°C. A newly developed system, HemoCue Glucose 201RT, has microcuvettes that can be stored at room temperature. Participants (n=444; 18-80 years old) in the EUROASPIRE IV survey, all with coronary artery disease, some with known diabetes, were investigated. Plasma glucose recordings, fasting in all participants and postprandial in the majority, were simultaneously recorded with both pieces of equipment. Congruence was expressed as median absolute difference and median absolute relative difference between the two sets of equipment and also compared according to the International Organization for Standardization (ISO) 15197:2013 criteria. Clinical accuracy was calculated with Clarke error grid analysis and cross-tabulated while considering different glucose categories (normal, impaired glucose tolerance, and diabetes). The median absolute difference between the two devices was +0.1 mmol/L, and the median absolute relative difference was +5.4%. This also corresponded with the ISO criteria. In the Clarke error grid, 99.8% ended up in Zones A and B, and 90% of the glucose values in the cross-table allocated the participant to the same glucose category. The HemoCue Glucose 201RT system is accurate, with small nonsystematic deviations, when compared with the commonly used HemoCue Glucose 201+. It is predicted that the HemoCue Glucose 201RT, which is more user friendly, will be a preferred alternative to the HemoCue Glucose 201+.

Accuracy evaluation of blood glucose monitoring systems in children on overnight closed-loop control.

This pilot study evaluated the difference in accuracy between the Bayer Contour® Next (CN) and HemoCue® (HC) glucose monitoring systems in children with type 1 diabetes participating in overnight closed-loop studies. Subjects aged 10-18 years old were admitted to a clinical research center and glucose values were obtained every 30 minutes overnight. Glucose values were measured using whole blood samples for CN and HC readings and results were compared to Yellow Springs Instrument (YSI) reference values obtained with plasma from the same sample. System accuracy was compared using mean absolute relative difference (MARD) and International Organization for Standardization (ISO) accuracy standards. A total of 28 subjects were enrolled in the study. Glucose measurements were evaluated at 457 time points. CN performed better than HC with an average MARD of 3.13% compared to 10.73% for HC (P < .001). With a limited sample size, CN met ISO criteria (2003 and 2013) at all glucose ranges while HC did not. CN performed very well, and would make an excellent meter for future closed-loop studies outside of a research center.

Performance Variability of Seven Commonly Used Self-Monitoring of Blood Glucose Systems: Clinical Considerations for Patients and Providers

Blood glucose data are frequently used in clinical decision making, thus it is critical that self-monitoring of blood glucose (SMBG) systems consistently provide accurate results. Concerns about SMBG accuracy have prompted the development of newly proposed International Organization for Standardization (ISO) standards: ≥ 95% of individual glucose results shall fall within ± 15 mg/dl of the results of the manufacturer's reference procedure at glucose concentrations <100 mg/dl and within ± 15% for values ≥ 100 mg/dl. We evaluated seven marketed systems against the current and proposed ISO criteria (criterion A). Capillary blood samples were collected from 100 subjects and tested on seven systems: Accu-Chek Aviva Plus, Advocate Redi-Code, Element, Embrace, Prodigy Voice, TRUEbalance, and WaveSense Presto. Results were compared with manufacturer's documented reference system, YSI or perchloric acid hexokinase; three different strip lots from each system were tested on each subject, in duplicate. Compared against current ISO criteria (≥ 95% within ± 15 mg/dl for values <75 mg/dl and ± 20% for values ≥ 75 mg/dl) the Accu-Chek Aviva Plus, Element, and WaveSense Presto systems met accuracy criteria. However, only the Accu-Chek Aviva Plus met the proposed ISO criteria (criterion A) in all three lots. The other six systems failed to meet the criteria in at least two of the three lots, showing lot-to-lot variability, high/low bias, and variations due to hematocrit. Inaccurate SMBG readings can potentially adversely impact clinical decision making and outcomes. Clinicians can reduce controllable variables by prescribing accurate SMBG systems. Adherence to the proposed ISO criteria should enhance patient safety by improving the accuracy of SMBG systems.

Accuracy of blood-glucose measurements using glucose meters and arterial blood gas analyzers in critically ill adult patients: systematic review

IntroductionGlucose control to prevent both hyperglycemia and hypoglycemia is important in an intensive care unit. Arterial blood gas analyzers and glucose meters are commonly used to measure blood-glucose concentration in an intensive care unit; however, their accuracies are still unclear.MethodsWe performed a systematic literature search (January 1, 2001, to August 31, 2012) to find clinical studies comparing blood-glucose values measured with glucose meters and/or arterial blood gas analyzers with those simultaneously measured with a central laboratory machine in critically ill adult patients.ResultsWe reviewed 879 articles and found 21 studies in which the accuracy of blood-glucose monitoring by arterial blood gas analyzers and/or glucometers by using central laboratory methods as references was assessed in critically ill adult patients. Of those 21 studies, 11 studies in which International Organization for Standardization criteria, error-grid method, or percentage of values within 20% of the error of a reference were used were selected for evaluation. The accuracy of blood-glucose measurements by arterial blood gas analyzers and glucose meters by using arterial blood was significantly higher than that of measurements with glucose meters by using capillary blood (odds ratios for error: 0.04, P < 0.001; and 0.36, P < 0.001). The accuracy of blood-glucose measurements with arterial blood gas analyzers tended to be higher than that of measurements with glucose meters by using arterial blood (P = 0.20). In the hypoglycemic range (defined as < 81 mg/dl), the incidence of errors using these devices was higher than that in the nonhypoglycemic range (odds ratios for error: arterial blood gas analyzers, 1.86, P = 0.15; glucose meters with capillary blood, 1.84, P = 0.03; glucose meters with arterial blood, 2.33, P = 0.02). Unstable hemodynamics (edema and use of a vasopressor) and use of insulin were associated with increased error of blood glucose monitoring with glucose meters.ConclusionsOur literature review showed that the accuracy of blood-glucose measurements with arterial blood gas analyzers was significantly higher than that of measurements with glucose meters by using capillary blood and tended to be higher than that of measurements with glucose meters by using arterial blood. These results should be interpreted with caution because of the large variation of accuracy among devices. Because blood-glucose monitoring was less accurate within or near the hypoglycemic range, especially in patients with unstable hemodynamics or receiving insulin infusion, we should be aware that current blood glucose-monitoring technology has not reached a high enough degree of accuracy and reliability to lead to appropriate glucose control in critically ill patients.

Evaluation of a Continuous Blood Glucose Monitoring System Using a Central Venous Catheter with an Integrated Microdialysis Function

Glycemic control in critically ill patients has been the topic of an interesting debate during the last decade. An accurate continuous glucose monitoring system is essential to better understand this field. This prospective study thus evaluates the accuracy and technical feasibility of a continuous glucose monitoring system using intravascular microdialysis. Thirty patients undergoing cardiac surgery were monitored using a triple-lumen central venous catheter (Eirus TLC; Eirus Medical AB, Solna, Sweden) with an integrated microdialysis function. The catheter functions as a central venous catheter, enabling blood sampling and administration of infusions and medication while simultaneously providing continuous glucose monitoring. The patients were monitored for up to 48 h postoperatively. As reference, arterial blood gas samples were taken every hour and analyzed in a blood gas analyzer. Six hundred seven paired samples were obtained for analysis. Using Clarke Error Grid analysis, 100% of the paired samples were in Zones A+B, and 97% were in Zone A. Mean difference (bias) was -0.12 mmol/L, and mean absolute relative difference was 5.6%. Of the paired samples, 97.5% were correct according to International Organization for Standardization criteria. Bland-Altman analysis showed bias ± limits of agreement were -0.12 ± 0.7 mmol/L. No hypoglycemic episodes were observed. Central venous microdialysis is an accurate and reliable method for continuous blood glucose monitoring up to 48 h in patients undergoing cardiac surgery. With the microdialysis function integrated in a central venous catheter, no extra device for the continuous glucose monitoring is required. The system may be useful in critically ill patients.

Effects of Simulated Altitude on Blood Glucose Meter Performance: Implications for In-Flight Blood Glucose Monitoring

Most manufacturers of blood glucose monitoring equipment do not give advice regarding the use of their meters and strips onboard aircraft, and some airlines have blood glucose testing equipment in the aircraft cabin medical bag. Previous studies using older blood glucose meters (BGMs) have shown conflicting results on the performance of both glucose oxidase (GOX)- and glucose dehydrogenase (GDH)-based meters at high altitude. The aim of our study was to evaluate the performance of four new-generation BGMs at sea level and at a simulated altitude equivalent to that used in the cabin of commercial aircrafts. Blood glucose measurements obtained by two GDH and two GOX BGMs at sea level and simulated altitude of 8000 feet in a hypobaric chamber were compared with measurements obtained using a YSI 2300 blood glucose analyzer as a reference method. Spiked venous blood samples of three different glucose levels were used. The accuracy of each meter was determined by calculating percentage error of each meter compared with the YSI reference and was also assessed against standard International Organization for Standardization (ISO) criteria. Clinical accuracy was evaluated using the consensus error grid method. The percentage (standard deviation) error for GDH meters at sea level and altitude was 13.36% (8.83%; for meter 1) and 12.97% (8.03%; for meter 2) with p = .784, and for GOX meters was 5.88% (7.35%; for meter 3) and 7.38% (6.20%; for meter 4) with p = .187. There was variation in the number of time individual meters met the standard ISO criteria ranging from 72-100%. Results from all four meters at both sea level and simulated altitude fell within zones A and B of the consensus error grid, using YSI as the reference. Overall, at simulated altitude, no differences were observed between the performance of GDH and GOX meters. Overestimation of blood glucose concentration was seen among individual meters evaluated, but none of the results obtained would have resulted in dangerous failure to detect and treat blood glucose errors or in giving treatment that was actually contradictory to that required.

Performance of a New Blood Glucose Monitoring System in the Hands of Intended Users

This study assessed the performance of a blood glucose monitoring system (BGMS) in development that uses a new generation of blood glucose test strips with capillary and venous blood in the hands of its intended users, people with diabetes and healthcare professionals (HCPs). In total, 93 subjects ≥ 18 years old (median age, 33 years) with type 1 (78%) or type 2 (22%) diabetes participated. Untrained subjects performed self-test fingersticks using a Microlet(®)2 lancing device (Bayer HealthCare LLC, Diabetes Care, Tarrytown, NY) followed by testing of their own capillary blood on the BGMS. HCPs performed fingersticks (using a Tenderlett(®) lancing device [International Technidyne Corp., Edison, NJ]) and venipunctures on subjects and tested both capillary and venous samples from subjects on the BGMS. All BGMS results were compared with Yellow Springs Instruments (YSI) (YSI Life Sciences, Inc., Yellow Springs, OH) laboratory results. Analytical accuracy was assessed according to International Organization for Standardization (ISO) 15197:2003 guidelines (i.e., within ± 15 mg/dL or ± 20% of the YSI results for samples with glucose concentrations < 75 mg/dL and ≥ 75 mg/dL, respectively) and more stringent criteria (i.e., within ± 15 mg/dL or ± 15% of the YSI results for samples with glucose concentrations < 100 mg/dL and ≥ 100 mg/dL, respectively). Overall, 98.9% (180/182) of subject Microlet2 capillary fingerstick results, 99.5% (182/183) of HCP Tenderlett capillary fingerstick results, and 100% (186/186) of venous results met current ISO criteria and more stringent criteria. The average hematocrit was 44%, with values ranging from 32% to 52%. Test results from both capillary fingerstick and venous samples with a new BGMS in development met current accuracy guidelines as well as proposed tighter criteria.