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Journal of Esthetic and Restorative... 2003Tooth whitening has become a popular and routine dental procedure, and its efficacy and safety have been well documented. However, the measurement of tooth color,...
UNLABELLED
Tooth whitening has become a popular and routine dental procedure, and its efficacy and safety have been well documented. However, the measurement of tooth color, particularly in the evaluation of the efficacy of a system intended to enhance tooth whiteness, remains a challenge. One of the instruments used for assessing tooth color in clinical whitening studies is the Minolta Chroma Meter CR-321 (Minolta Corporation USA, Ramsey, NJ, USA). This article describes the instrument and discusses various measuring procedures and the Chroma Meter's advantages, limitations, and disadvantages. The available information indicates that, although Minolta Chroma Meter CR-321 provides quantitative and objective measurements of tooth color, it can be tedious to use with a custom alignment device. The Chroma Meter data are inconsistent with the commonly used visual instruments such as Vitapan Classical Shade Guide (Vita Zahnfabrik, Bad Säckingen, Germany), although in many cases the general trends are similar. It is also questionable whether the small area measured adequately represents the color of the whole tooth. A more critical challenge is the lack of methods for interpreting the Chroma Meter data regarding tooth color change in studies evaluating the efficacy of whitening systems. Consequently, at present the Chroma Meter data alone do not appear to be adequate for determining tooth color change in whitening research, although the quantitative measurements may be useful as supplemental or supportive data. Research is needed to develop and improve the instrument and technique for quantitative measurement of tooth color and interpretation of the data for evaluating tooth color change.
CLINICAL SIGNIFICANCE
This paper will help readers to understand the advantages and limitations of the Minolta Chroma Meter used for evaluating the efficacy of tooth-whitening systems so that proper judgment can be made in the interpretation of the results of clinical studies.
Topics: Color; Colorimetry; Equipment Design; Humans; Surface Properties; Tooth; Tooth Bleaching
PubMed: 15000903
DOI: 10.1111/j.1708-8240.2003.tb00316.x -
Journal of Diabetes Science and... Jul 2012Most 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... (Comparative Study)
Comparative Study
BACKGROUND
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.
METHODOLOGY/PRINCIPAL FINDINGS
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.
CONCLUSIONS
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.
Topics: Aircraft; Altitude; Atmospheric Pressure; Blood Glucose; Blood Glucose Self-Monitoring; Computer Simulation; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Efficiency; Equipment Design; Humans; Reference Standards; Travel
PubMed: 22920813
DOI: 10.1177/193229681200600418 -
The Medical Journal of Australia Apr 1990This study was designed to evaluate the Breath-Taker peak flow meter, recently released by the Asthma Foundation of Victoria. The performance characteristics of five... (Clinical Trial)
Clinical Trial Randomized Controlled Trial
This study was designed to evaluate the Breath-Taker peak flow meter, recently released by the Asthma Foundation of Victoria. The performance characteristics of five Breath-Taker units were compared with those of five Wright and five mini-Wright peak flow meters. The between-unit reproducibility of each type of peak flow meter was measured using an explosive decompression device with a peak flow reproducibility of better than 1%. Each individual meter was used to measure the peak flow delivered by the decompression device three times for each of six flow rates (97-622 L/min). The coefficient of variation (CV) was lowest for the Wright meters (mean CV, 4.8%) and, similarly to the Breath-Taker units (mean CV, 8.4%), this decreased with increasing flow. The CV of the mini-Wright meters, however, increased as flow increased (mean CV, 7.5%). The Breath-Taker meter had less inter-unit variability than the mini-Wright meter at peak flows above 200 L/min. The accuracy of the three meter types was assessed by comparing measurements of peak expiratory flow rate (PEFR) made with each type and also with a computerized pneumotachograph system in 30 subjects with various degrees of irreversible airflow obstruction. Each subject performed at least three reproducible PEFR manoeuvres on the pneumotachograph and on each type of meter, in randomized order. The results showed that in comparison with the pneumotachograph system the Breath-Taker meter underestimated PEFRs by a mean of 27 L/min and the mini-Wright meter overestimated PEFRs by a mean of 45 L/min, whereas the Wright meter was not significantly different. Since the differences between the Breath-Taker meter and the pneumotachograph were independent of flow rate, a scale offset would suffice to "correct" the Breath-Taker readings.
Topics: Adolescent; Adult; Aged; Evaluation Studies as Topic; Humans; Middle Aged; Peak Expiratory Flow Rate; Respiratory Function Tests
PubMed: 2093803
DOI: 10.5694/j.1326-5377.1990.tb125184.x -
International Ophthalmology Oct 2015To assess the accuracy of standard clinical grading of aqueous flare in uveitis according to the Standardization of Uveitis Nomenclature consensus, and compare the... (Comparative Study)
Comparative Study
To assess the accuracy of standard clinical grading of aqueous flare in uveitis according to the Standardization of Uveitis Nomenclature consensus, and compare the results with the readings of the laser flare meter, Kowa 500. Two examiners clinically graded the flare in 110 eyes. The flare was then measured using the Kowa laser flare meter. Twenty-nine eyes were graded as anterior chamber flare +2; for 18 of these, the clinicians were in agreement, the rest differed by the order of one grade. The range of the laser flare meter for these eyes was 5.2-899.1 photons/ms. The median value was 41.4. Seventy-four eyes were graded with flare +1. Agreement was established in 51 of these eyes. Disagreement for the rest was again by the order of 1, and the flare meter range was 1.1-169.9 photons/ms, median value 18.4. For the clinical measure of flare 0, the clinicians disagreed on three out of five eyes. The flare meter readings ranged from 2.5 to 14.1 photons/ms, median value 9.9. Only two eyes were graded with flare +3 and there was one step disagreement on both of them. We found little evidence of association between the flare readings and intraocular pressure or age. Our findings suggest that clinical evaluation of aqueous flare is subjective. Compared with the Kowa laser flare meter's numeric readings, the discrepancies observed indicate that clinical grading is an approximate science. The laser flare meter provides an accurate, reproducible, non-invasive assessment of aqueous flare that can prove valuable in research and clinical decisions.
Topics: Adult; Anterior Chamber; Aqueous Humor; Blood-Aqueous Barrier; Female; Humans; Intraocular Pressure; Male; Middle Aged; Uveitis
PubMed: 22855363
DOI: 10.1007/s10792-012-9616-3 -
Diabetes Technology & Therapeutics Apr 2008This study compared the accuracy and precision of five blood glucose (BG) meters. (Comparative Study)
Comparative Study Randomized Controlled Trial
BACKGROUND
This study compared the accuracy and precision of five blood glucose (BG) meters.
METHODS
Diabetes patients undergoing venipuncture for glucose testing were randomized to one of two groups consisting of three meters: FreeStyle Flash (Abbott Diabetes Care, Alameda, CA), Accu-Chek Advantage (Roche Diagnostics Corp., Indianapolis, IN), and Accu-Chek Compact Plus (Roche Diagnostics) or FreeStyle Flash, Ascensia Contour (Bayer Healthcare, Diagnostic Division, Tarrytown, NY), and BD Logic (BD Diabetes Care, Franklin Lake, NJ). Within 5 min following venipuncture, duplicate finger BG measurements from three ipsilateral fingers were taken. Finger glucose measurements were compared with laboratory reference values. Accuracy was assessed by a Clarke error grid analysis (EGA) and within 10% of the laboratory value criteria. Meter precision was determined by calculating the absolute mean differences in glucose values between duplicate samples.
RESULTS
Finger sticks were obtained from 202 patients. Mean venipuncture BG was 148 mg/dL (SD +/- mg/64 dL; range 25-439 mg/dL). Accuracy by Clarke EGA (Zone A results) was demonstrated in 69% of Advantage samples, 75% of Compact Plus, and 96% of the first group of Flash versus 88% of the Contour, 67% of the Logic, and 91% of the second Flash samples (P < 0.05 for both Flash and Contour). Meter accuracy using the 10% criteria was demonstrated in 30%, 38%, 70%, 46%, 48%, and 68% of the samples, respectively (P < 0.05 for both Flash groups compared to each of the other meters). There were no differences in meter precision.
CONCLUSIONS
No statistically significant differences in accuracy were evident using the Clarke EGA criteria (pooled results of Zone A and B), though the more strict 20% accuracy criteria (Zone A results only) found the Flash and Contour to have significantly greater accuracy compared to the Advantage, Compact Plus, and the Logic. Using the 10% accuracy criteria found the Flash to have significantly greater accuracy than each of the other four meters. All five meters demonstrated similar precision.
Topics: Aged; Blood Glucose; Blood Glucose Self-Monitoring; Diabetes Mellitus; Female; Humans; Insulin; Male; Middle Aged; Postprandial Period; Reproducibility of Results
PubMed: 18260773
DOI: 10.1089/dia.2007.0244 -
Journal of Diabetes Science and... Jul 2009Glucose meters are universally utilized in the management of hypoglycemic and hyperglycemic disorders in a variety of healthcare settings. Establishing the accuracy of... (Review)
Review
Glucose meters are universally utilized in the management of hypoglycemic and hyperglycemic disorders in a variety of healthcare settings. Establishing the accuracy of glucose meters, however, is challenging. Glucose meters can only analyze whole blood, and glucose is unstable in whole blood. Technical accuracy is defined as the closeness of agreement between a test result and the true value of that analyte. Truth for glucose is analysis by isotope dilution mass spectrometry, and frozen serum standards analyzed by this method are available from the National Institute of Standards and Technology. Truth for whole blood has not been established, and cells must be separated from the whole blood matrix before analysis by a method like isotope dilution mass spectrometry. Serum cannot be analyzed by glucose meters, and isotope dilution mass spectrometry is not commonly available in most hospitals and diabetes clinics to evaluate glucose meter accuracy. Consensus standards recommend comparing whole blood analysis on a glucose meter against plasma/serum centrifuged from a capillary specimen and analyzed by a clinical laboratory comparative method. Yet capillary samples may not provide sufficient volume to test by both methods, and venous samples may be used as an alternative when differences between venous and capillary blood are considered. There are thus multiple complexities involved in defining technical accuracy and no clear consensus among standards agencies and professional societies on accuracy criteria. Clinicians, however, are more concerned with clinical agreement of the glucose meter with a serum/plasma laboratory result. Acceptance criteria for clinical agreement vary across the range of glucose concentrations and depend on how the result will be used in screening or management of the patient. A variety of factors can affect glucose meter results, including operator technique, environmental exposure, and patient factors, such as medication, oxygen therapy, anemia, hypotension, and other disease states. This article reviews the challenges involved in obtaining accurate glucose meter results.
Topics: Blood Glucose; Blood Glucose Self-Monitoring; Humans; Reproducibility of Results
PubMed: 20144348
DOI: 10.1177/193229680900300446 -
Critical Care Medicine Sep 2017Due to accuracy concerns, the Food and Drug Administration issued guidances to manufacturers that resulted in Center for Medicare and Medicaid Services stating that the...
OBJECTIVE
Due to accuracy concerns, the Food and Drug Administration issued guidances to manufacturers that resulted in Center for Medicare and Medicaid Services stating that the use of meters in critically ill patients is "off-label" and constitutes "high complexity" testing. This is causing significant workflow problems in ICUs nationally. We wished to determine whether real-world accuracy of modern glucose meters is worse in ICU patients compared with non-ICU inpatients.
DESIGN
We reviewed glucose results over the preceding 3 years, comparing results from paired glucose meter and central laboratory tests performed within 60 minutes of each other in ICU versus non-ICU settings.
SETTING
Seven ICU and 30 non-ICU wards at a 1,300-bed academic hospital in the United States.
SUBJECTS
A total of 14,763 general medicine/surgery inpatients and 20,970 ICU inpatients.
INTERVENTIONS
None.
MEASUREMENTS AND MAIN RESULTS
Compared meter results with near simultaneously performed laboratory results from the same patient by applying the 2016 U.S. Food and Drug Administration accuracy criteria, determining mean absolute relative difference and examining where paired results fell within the Parkes consensus error grid zones. A higher percentage of glucose meter results from ICUs than from non-ICUs passed 2016 Food and Drug Administration accuracy criteria (p < 10) when comparing meter results with laboratory results. At 1 minute, no meter result from ICUs posed dangerous or significant risk by error grid analysis, whereas at 10 minutes, less than 0.1% of ICU meter results did, which was not statistically different from non-ICU results.
CONCLUSIONS
Real-world accuracy of modern glucose meters is at least as accurate in the ICU setting as in the non-ICU setting at our institution.
Topics: Academic Medical Centers; Blood Glucose; Humans; Intensive Care Units; Point-of-Care Systems; Reference Standards; United States; United States Food and Drug Administration
PubMed: 28640025
DOI: 10.1097/CCM.0000000000002572 -
The Review of Scientific Instruments Apr 2011The power measurement of high-power continuous-wave laser beams typically calls for the use of water-cooled thermopile power meters. Large thermopile meters have slow...
The power measurement of high-power continuous-wave laser beams typically calls for the use of water-cooled thermopile power meters. Large thermopile meters have slow response times that can prove insufficient to conduct certain tests, such as determining the influence of atmospheric turbulence on transmitted beam power. To achieve faster response times, we calibrated a digital camera to measure the power level as the optical beam is projected onto a white surface. This scattered-light radiometric power meter saves the expense of purchasing a large area power meter and the required water cooling. In addition, the system can report the power distribution, changes in the position, and the spot size of the beam. This paper presents the theory of the scattered-light radiometric power meter and demonstrates its use during a field test at a 2.2 km optical range.
PubMed: 21528989
DOI: 10.1063/1.3574218 -
Medical Physics Dec 2013Liquid crystal displays used to interpret medical images are often equipped with built-in luminance meters to evaluate luminance response and Grayscale Standard Display...
PURPOSE
Liquid crystal displays used to interpret medical images are often equipped with built-in luminance meters to evaluate luminance response and Grayscale Standard Display Function conformance. This work evaluates agreement between luminance reported by the built-in meters and external measurements.
METHODS
The white level luminance was measured using a built-in meter and an external meter for 93 primary review workstations (Models MFGD 3420 and MDCG 3120-CB) with between 117 and 49,336 backlight hours (BLH). Measured luminance values were compared via t-test for displays with less than 25,000 BLH and those with more than 25,000 BLH. Bias between meters was also evaluated. Changes in luminance uniformity with increasing backlight hours were explored by determining the maximum luminance deviation (MLD) for subsets of these displays with less than 800 BLH and greater than 35,000 BLH.
RESULTS
The mean difference between built-in and external luminance measurements was 5.84% and 38.92% for displays with less than 25,000 and greater than 25,000 BLH, respectively, with a statistically significant difference in the means (p < 0.001). For displays with low BLH, a statistically significant bias was observed (p < 0.001) between built-in and external measurements. A high degree of correlation was observed between measurements made with two separate external meters (r = 0.999). The mean MLD was 9.5% and 11.2% for MDCG 3120-CB displays with less than 800 and greater than 35,000 BLH, respectively. The difference in the mean values was not statistically significant (p < 0.001).
CONCLUSIONS
Disagreement between the white level luminance measured using the built-in and external meter increased with BLH. Consequently, reliance on values reported by the built-in luminance meter may result in a reduction in image contrast with time. Recommendations have been proposed regarding luminance response testing and corrective action for failing displays.
Topics: Diagnostic Imaging; Image Processing, Computer-Assisted; Light; Liquid Crystals; Time Factors
PubMed: 24320513
DOI: 10.1118/1.4829497 -
The Journal of the Acoustical Society... Aug 2017Transit-time flow meters based on guided ultrasonic wave propagation in the pipe spool have several advantages compared to traditional inline ultrasonic flow metering....
Transit-time flow meters based on guided ultrasonic wave propagation in the pipe spool have several advantages compared to traditional inline ultrasonic flow metering. The extended interrogation field, obtained by continuous leakage from guided waves traveling in the pipe wall, increases robustness toward entrained particles or gas in the flow. In reflective-path guided-wave ultrasonic flow meters (GW-UFMs), the flow equations are derived from signals propagating solely in the pipe wall and from signals passing twice through the fluid. In addition to the time-of-flight (TOF) through the fluid, the fluid path experiences an additional time delay upon reflection at the opposite pipe wall due to specular and non-specular reflections. The present work investigates the influence of these reflections on the TOF in a reflective-path GW-UFM as a function of transducer separation distance at zero flow conditions. Two models are used to describe the signal propagation through the system: (i) a transient full-wave finite element model, and (ii) a combined plane-wave and ray-tracing model. The study shows that a range-dependent time delay is associated with the reflection of the fluid path, introducing transmitter-receiver distance dependence. Based on these results, the applicability of the flow equations derived using model (ii) is discussed.
PubMed: 28863617
DOI: 10.1121/1.4996851