Central Laboratory Methods Research Articles

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 the performance of urine albumin, creatinine and albumin–creatinine ratio assay on two POCT analyzers relative to a central laboratory method

BackgroundThe evaluation of microalbumin, creatinine and albumin–creatinine ratio is very important in patients with diabetes for the early detection of kidney disease and the identification of patients at risk for complications from diabetes or hypertension. MethodsA total of 88 spot urine samples previously analyzed using the Vitros 5,1 FS (creatinine) and Beckman Coulter Immage (microalbumin) located in the central laboratory and having microalbumin and creatinine values within the Afinion and DCA Vantage reportable ranges were run on 2 point of care ( POC) instruments (Siemens DCA Vantage and Axis-Shield Afinion). ResultsThe mean values for the DCA Vantage were: 42.6mg/l for albumin, 10.3mol/l for creatinine, and 5.4mg/mol for ACR. For the Afinion AS100, the mean values were: 48.5mg/l for albumin, 9.5mol/l for creatinine, and 6.7mg/mol for ACR. The mean values obtained for CL were: 40.8mg/l for albumin, 10.0mol/l for creatinine, and 5.4mg/mol for ACR. All POC analyzers showed good correlation to the central laboratory tests for microalbumin, creatinine and albumin creatinine ratio (ACR) for Afinion (R2=0.954, 0.974, and 0.964, respectively) and DCA Vantage (R2=0.989, 0.987, and 0.991, respectively). With the exception of the DCA Vantage ACR (p=0.53), the levels of microalbumin, creatinine and ACR obtained for the Afinion and DCA Vantage instruments as compared to the CL were statistically different (p<0.05). The inter and intraday imprecision for both POC instruments was <2.9% and total imprecision <8.7%. ConclusionsThe 2 instruments evaluated in this study were in good agreement with the quantitative laboratory results and thus can be used for microalbumin, creatinine and ACR assays at the POC. However, facilities using Afinion will have to use different normal range for ACR.

Investigating Interferences of a Whole-Blood Point-of-Care Creatinine Analyzer: Comparison to Plasma Enzymatic and Definitive Creatinine Methods in an Acute-Care Setting

Although measurement of whole-blood creatinine at the point of care offers rapid assessment of renal function, agreement of point-of-care (POC) results with central laboratory methods continues to be a concern. We assessed the influence of several potential interferents on POC whole-blood creatinine measurements. We compared POC creatinine (Nova StatSensor) measurements with plasma enzymatic (Roche Modular) and isotope dilution mass spectrometry (IDMS) assays in 119 hospital inpatients. We assessed assay interference by hematocrit, pH, pO(2), total and direct bilirubin, creatine, prescribed drugs, diagnosis, red blood cell water fraction, and plasma water fraction. CVs for POC creatinine were 1.5- to 6-fold greater than those for plasma methods, in part due to meter-to-meter variation. Regressioncomparison of POC creatinine to IDMS results gave a standard error (S(y|x)) of 0.61 mg/dL (54 μmol/L), whereas regression of plasma enzymatic creatinine to IDMS was S(y|x) 0.16 mg/dL (14 μmol/L). By univariate analysis, bilirubin, creatine, drugs, pO(2), pH,plasma water fraction, and hematocrit were not found to contribute to method differences. However, multivariate analysis revealed that IDMS creatinine, red blood cell and plasma water fractions, and hematocrit explained 91.8% of variance in POC creatinine results. These data suggest that whole-blood POC creatinine measurements should be used with caution. Negative interferences observed with these measurements could erroneously suggest adequate renal function near the decision threshold, particularly if estimated glomerular filtration rate is determined. Disparity between whole-blood and plasma matrices partially explains the discordance between whole-blood and plasma creatinine methods.

Evaluation of First-Draw Whole Blood, Point-of-Care Cardiac Markers in the Context of the Universal Definition of Myocardial Infarction: A Comparison of a Multimarker Panel to Troponin Alone and to Testing in the Central Laboratory

Previous studies evaluating point-of-care testing (POCT) for cardiac biomarkers did not use current recommendations for troponin cutoff values or recognize the recent universal definition of acute myocardial infarction. Traditionally, achieving optimal sensitivity for the detection of myocardial injury on initial presentation required combining cardiac troponin and/or creatine kinase isoenzyme MB with an early marker, usually myoglobin. In recent years, the performance of central laboratory combining cardiac troponin assays has improved significantly, potentially obviating the need for a multimarker panel to achieve optimum sensitivity. To compare 2 commonly used POCT strategies to a fourth generation, central laboratory cardiac troponin T assay on first-draw specimens from patients being evaluated for acute myocardial infarction in the emergency department. The 2 strategies included a traditional POCT multimarker panel and a newer POCT method using cardiac troponin I alone. Blood specimens from 204 patients presenting to the emergency department with signs and/or symptoms of myocardial ischemia were measured on the 2 POCT systems and by a central laboratory method. The diagnosis for each patient was determined by retrospective chart review. The cardiac troponin T assasy alone was more sensitive for acute myocardial infarction than the multimarker POCT panel with equal or better specificity. When compared with a POCT troponin I, the cardiac troponin T was also more sensitive, but this difference was not significant. The POCT troponin I alone also had the same sensitivity as the multimarker panel. Testing for combining cardiac troponin alone using newer, commercially available, central laboratory or POCT assays performed with equal or greater sensitivity to acute myocardial infarction as the older, traditional, multimarker panel. In the near future, high-sensitivity, central laboratory troponins will be available for routine clinical use. As a result, the quality gap between central laboratories and older POCT methods will continue to widen, unless the performance of the POCT methods is improved.

Hemoglobin A1c: Assessment of three POC analyzers relative to a central laboratory method

Background Glycosylated hemoglobin evaluation is very important for assessing the control of diabetes. Since the use of point-of-care (POC) devices for monitoring HbA1c is increasing, it is important to determine how these devices compare in relation to instrumentation used in the central laboratory (CL). Methods Eighty-eight randomly selected samples previously analyzed using the Bio-Rad Variant™ II Hemoglobin Testing System were run on three POC Analyzers (Siemens DCA Vantage™ Analyzer, Axis-Shield Afinion™ AS100 Analyzer, and Bio-Rad In2it™ Analyzer). Results All POC instruments showed good correlation to the CL method (R 2 > 0.95 for all methods). HbA1c levels obtained using Variant II (mean = 7.9; 95% CI = 7.5–8.3%) and In2it (mean = 7.9; 95% C.I. = 7.5 –8.2%) instruments were found to have no statistical mean difference ( p = 0.21), while the values obtained using DCA Vantage (mean = 7.2% C.I. = 6.9 –7.5%) and Afinion (mean = 7.3% C.I. = 7.0 –7.6%) instruments were different ( p < 0.001) from those of the CL method. The Afinion and DCA Vantage instruments increasingly underestimated the HbA1c compared to the CL as the HbA1c values increased. These differences were even more striking when the estimated average glucose is calculated. Conclusions Despite significant variation of results among the POC instruments evaluated relative to the CL method and pending resolution of HbA1c standardization issues, we conclude that all of the POC instruments can be used for HbA1c determination if clinicians are given instrument specific reference ranges.

Two different hematocrit detection methods: Different methods, different results?

BackgroundLess is known about the influence of hematocrit detection methodology on transfusion triggers. Therefore, the aim of the present study was to compare two different hematocrit-assessing methods. In a total of 50 critically ill patients hematocrit was analyzed using (1) blood gas analyzer (ABLflex 800) and (2) the central laboratory method (ADVIA® 2120) and compared.FindingsBland-Altman analysis for repeated measurements showed a good correlation with a bias of +1.39% and 2 SD of ± 3.12%. The 24%-hematocrit-group showed a correlation of r2 = 0.87. With a kappa of 0.56, 22.7% of the cases would have been transfused differently. In the-28%-hematocrit group with a similar correlation (r2 = 0.8) and a kappa of 0.58, 21% of the cases would have been transfused differently.ConclusionsDespite a good agreement between the two methods used to determine hematocrit in clinical routine, the calculated difference of 1.4% might substantially influence transfusion triggers depending on the employed method.

Implementation of a Rapid Whole Blood D-Dimer Test in the Emergency Department of an Urban Academic Medical Center

Overcrowding and prolonged patient length-of-stay (LOS) in emergency departments (EDs) are growing problems. We evaluated the impact of implementing a rapid whole blood quantitative D-dimer test (Biosite Triage, Biosite Diagnostics, San Diego, CA) in our ED satellite laboratory on 252 patients before vs 211 patients after implementation. All patients also underwent testing with the existing central laboratory method (VIDAS D-dimer, bioMérieux, Durham, NC). D-dimer turnaround time (from blood draw to result) decreased approximately 79% (approximately 2 hours vs 25 minutes). The mean ED LOS declined from 8.46 to 7.14 hours (P = .016). Hospital admissions decreased 13.8%, ED discharges increased 7.3%, and the number of patients admitted for observation increased 6.4% (P = .005). No difference in the utilization of radiologic studies was observed (P = .86). At 3 months' follow-up, none of the after-implementation patients with negative D-dimer results were admitted for subsequent venous thromboembolic disease. The rapid D-dimer test was associated with a shorter ED LOS and fewer hospital admissions.

Haemoglobin A1c: evaluation of a new HbA1c point-of-care analyser Bio-Rad in2it in comparison with the DCA 2000 and central laboratory analysers

Point-of-care-testing (POCT) of haemoglobin Alc (HbA1c) is popular due to its fast turnaround of results in the outpatient setting. The aim of this project was to evaluate the performance of a new HbA1c POCT analyser, the Bio-Rad in2it, and compare it with the Siemens DCA 2000, Bio-Rad Variant II and Roche Tina-quant HbA1c Gen 2 assay on the cobas c501. Imprecision of the four methods were compared by computing total imprecision from within-run and between-run data. A total of 80 samples were also compared and analysed by Deming regression and Altman-Bland difference test. Study of total imprecision of the in2it at HBA1c levels of 6.0% and 10.4% produced a coefficient of variation (%CV) of 3.8% and 3.7%, respectively. These results were more favourable as compared with the DCA 2000 but did not match the low imprecision of the central laboratory methods, the Bio-Rad Variant II and the Roche cobas c501. Comparison between the in2it and the central laboratory analysers, Bio-Rad variant II and cobas c501, revealed positive bias of 12% and 10%, respectively, supported by corresponding Deming regression equation slopes of +1.18 and +1.14. Comparison between the DCA 2000 and the central laboratory analysers revealed a bias that became increasingly positive with rising HbA1c concentrations with Deming regression analysis also revealing proportional and constant differences. The in2it is a suitable POCT analyser for HbA1c but its less than ideal precision performance and differences with the central laboratory analysers must be communicated to and noted by the users.

Reliability of two different bedside assays for C-reactive protein in newborn infants

Bedside tests for C-reactive protein (CRP) have been studied in pediatric patients, but not in neonates. This study compared the results of two rapid bedside tests for CRP (Quick-Read CRP, Orion Diagnostic, Espoo, Finland and NycoCard CRP-Single Test, Axis-Shield, Oslo, Norway) with those of our central laboratory method (CRP-Lab) in newborn infants. CRP concentrations were determined using 72 samples obtained from 43 infants with suspected sepsis occurring between 1 and 28 days of life. Considering positive CRP concentrations to be > or = 10 mg/L, both bedside tests had good specificity (Quick-Read 80.5%, NycoCard 83.3%) and sensitivity (Quick-Read 97.2%, NycoCard 94.4%) when compared with our CRP-Lab. The agreement of measurement with central laboratory values was high for both the bedside tests, without statistically significant differences between the methods. The Quick-Read and NycoCard methods did not show any statistically significant systematic proportional bias when compared with the central laboratory values. The accuracy of the results of both bedside tests is somewhat decreased when CRP concentrations are >100 mg/L. This study shows that both the Quick-Read and the NycoCard test can be used for serial determinations of CRP concentrations in newborn infants. They require small volumes of blood and provide reliable results in < 5 min.

Comparison of Emergency Department Patient Classification by Point-of-Care and Central Laboratory Methods for Cardiac Troponin I

For patients admitted to the emergency department (ED) with suspected acute coronary syndrome, we compared results of a rapid, point-of-care whole blood assay for cardiac troponin I (Abbott i-STAT, Abbott Point-of-Care, East Windsor, NJ) (Tn-P) with an automated central laboratory plasma assay (Siemens TnI-Ultra, Siemens Medical Solutions Diagnostics, Tarrytown, NY) (Tn-U). Clinical data were obtained during a 6-month period during which ED patients were screened by Tn-P, with retesting of elevated results by Tn-U. Of 5,909 Tn-P results, 573 (9.7%) were elevated; these and a random selection of 137 negative specimens were retested by Tn-U. Of the specimens with elevated results, 4.5% retested negative by Tn-U, even though Tn-U typically gave about 50% higher results and had a lower manufacturer-specified 99th percentile cutoff. Of the negatives, 5.8% retested as elevated by Tn-U, but with levels no higher than 0.1 ng/mL (0.1 microg/L). Rapid whole blood testing for cardiac troponin I gave generally reliable patient classifications compared with plasma testing in the central laboratory, but besides missing small elevations, produced some apparent false-positives.

Implementation of Point-of-Care Rapid Urine Testing for Drugs of Abuse in the Emergency Department of an Academic Medical Center

We evaluated the impact of implementing a point-of-care (POC) rapid urine test panel for drugs of abuse on turnaround time (TAT), emergency department length of stay (LOS), and laboratory test utilization patterns. The mean TAT from sample collection to results reporting decreased by 69.4%, from 108 to 33 minutes, the mean LOS from 11.1 to 8.1 hours (27% P < .0001), and the median LOS from 8.0 to 7.0 hours (13% P = .0017). A method crossover between the POC and central laboratory methods revealed differences in sensitivity and specificity. Overall, there was no clear preference for either method. Differences in performance for individual drug classes were reconciled by providing interpretive comments with POC results. Following implementation, use of urine testing for drugs of abuse increased by 30%, which was offset by fewer requests for extended toxicology testing in the central laboratory and more selective ordering of toxicology tests not on the POC panel (alcohols and analgesics). The implementation of a POC urine test panel for drugs of abuse decreased LOS and TAT and essentially replaced central laboratory testing for drugs of abuse. Differences in sensitivity and specificity between POC and central laboratory results require provision of interpretive comments with results.

Analytic Bias Among Certified Methods for the Measurement of Hemoglobin A1c

We studied the magnitude, significance, and origin of an analytic bias that emerged between our point-of-care (POC) and our central laboratory (CL) methods for the measurement of hemoglobin A1c (HbA1c) and evaluated the analytic accuracy of 7 commonly used HbA1c methods relative to the National Glycohemoglobin Standardization Program (NGSP) reference method. The POC and CL methods were compared by split-sample analysis of clinical specimens and time series analyses of the HbA1c results reported for a 33-month period. The relative accuracies of 7 HbA1c methods were evaluated using College of American Pathologists proficiency survey results. Long-term drifts in the CL- and POC-analyzed test results caused the median intermethod bias [(POC result)-(CL result)] to increase from -0.4% to -0.9% HbA1c. Systematic biases, drifts in analytic performance over time, and intermethod variability were frequently observed among the 7 NGSP-certified HbA1c methods. Intermethod variability is a potential source of inaccuracy whenever HbA1c results are interpreted relative to universal, fixed, clinical decision thresholds.

The Alexander Project: the benefits from a decade of surveillance

The Alexander Project, initiated in 1992 as an international, multicentre, longitudinal surveillance study of antimicrobial susceptibility among common respiratory pathogens, has been pivotal in defining the role of global surveillance. At the time, there were few studies in which data were collected in a way that allowed meaningful comparisons to be made between studies, locations or over time. The project instituted the use of a central laboratory and standardized methods for the collection of isolates and determination of susceptibility, and this was continued with the addition of two further reference laboratories. Data from the study have provided a resource for measuring trends in the susceptibility patterns of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis at country, regional and global levels. Determination and publication of quantitative MICs enabled detailed assessment of changes in susceptibility distributions and assessment of microbiological and potential clinical susceptibility using different breakpoints, including those based on pharmacokinetic/pharmacodynamic parameters. Comparisons of antimicrobial usage patterns and resistance prevalences over time allowed hypotheses to be examined with respect to the role of quantity and type of antimicrobial use in the selection and spread of resistance. The resulting collection of isolates has provided a valuable resource for molecular studies into the evolution of resistance over time and location; a substantial proportion of this collection is now in the public domain. This paper reviews the 10 years of the Alexander Project and the benefits it has brought to an understanding of the evolution of antibacterial resistance in community respiratory bacteria.

Comparison of fingerstick hemoglobin A1c levels assayed by DCA 2000 with the DCCT/EDIC central laboratory assay: results of a Diabetes Research in Children Network (DirecNet) Study

The Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) high-performance liquid chromatography (HPLC) method for measuring hemoglobin A1c (HbA1c) serves as a reference standard against which other assays are compared. The DCA 2000 + Analyzer (Bayer Inc., Tarrytown, NY, USA), which uses an immunoassay, is a very popular device for measuring HbA1c levels in pediatric diabetes practices. To determine how HbA1c values measured with the DCA 2000 in a multisite, pediatric diabetes clinic setting compare with corresponding HbA1c values measured in the DCCT/EDIC laboratory. To examine this question, the Diabetes Research in Children Network (DirecNet) used the DCA 2000 in five clinical centers to measure baseline HbA1c levels in 200 youth with type 1 diabetes mellitus (T1DM) (aged 12.5 +/- 2.8 yr) who were participating in an outpatient clinical trial. At the same visit, an additional blood sample was obtained, refrigerated, and shipped to the DCCT/EDIC central laboratory for determination of HbA1c values. The central laboratory HbA1c value averaged 8.0 +/- 0.9% (mean +/- SD), with a median (25th and 75th quartiles) of 7.8% (7.3 and 8.5%, respectively). The DCA 2000 HbA1c values were strongly correlated (r = 0.94, p < 0.001), but significantly higher than DCCT/EDIC central laboratory values with a mean difference of +0.2% (95% confidence interval +0.14 to 0.23%, p < 0.001). There was some variation in the differences between DCA 2000 and central laboratory values at the five clinical centers (p < 0.001) with mean differences ranging between 0.0 and 0.3%, but differences between the two methods did not vary significantly by age or gender. Measurements of HbA1c by the DCA 2000 compare favorably with the DCCT/EDIC central laboratory method, albeit with slightly higher values.

Evaluation of the Bayer Multistix PRO 10LS Point-of-Care Urine Test

Urine strip tests for use at the point-of-care and centralized laboratory locations are commonplace and provide clinical information on kidney function, urinary tract infections, glucose handling, and liver function. The Multistix PRO 10LS is a new strip incorporating an extra protein pad with increased specificity for urinary albumin and a pad for urinary creatinine estimation, thus allowing calculation of the urinary protein-to-creatinine ratio. In this study, freshly voided urine samples were obtained from a total of 881 patients attending a variety of outpatient clinics. Protein, creatinine, and their ratio were estimated using the Multistix PRO 10LS strip, followed by analysis within a few hours using the central laboratory methods for protein, albumin, and creatinine. More than 90% of laboratory protein and creatinine measurements agreed to within one band of the Multistix PRO 10LS estimations. Diagnostic performance for the detection of clinically relevant proteinuria (defined by urinary albumin ≥80 mg/L) demonstrated a sensitivity of 96.5% and a specificity of 94.9%. An abnormal protein-to-creatinine ratio as detected by the Multistix PRO 10LS strip agreed with the central laboratory method in 94.6% of samples. The Multistix PRO 10LS urine strip test provides useful urinalysis information, including improved renal protein handling data in the form of the protein-to-creatinine ratio. Availability of this at the point of care thus will potentially augment immediate clinical decision making while the patient is physically at the outpatient clinic.

Introduction of an Albumin-to-Creatinine Ratio Point-of-Care Device: Analytic, Clinical, and Cost-effectiveness Aspects

Diabetic nephropathy is a long-term complication of diabetes that is associated with progressive renal failure as well as an increased risk for cardiovascular disease. Microalbuminuria is an accepted predictive marker for the early detection of impending renal disease in diabetic patients. The authors carried out a prospective, pragmatic study of the analytic, clinical, and cost-effectiveness aspects of a microalbumin point-of-care (POC) device in the diabetic clinic setting in comparison with the central laboratory method of quantification. Different testing strategies and their associated costs were then evaluated. In comparison with the central laboratory quantification, POC estimations of albumin and creatinine agreed to within one detection band in 91.8% and 82.6% of results respectively. The POC albumin-to-creatinine ratio was in agreement with the laboratory estimations in 89.7% of cases. Sample turnaround time was reduced markedly, and 93% of responding clinician's found the service useful. A modeled screening strategy using the POC device to select abnormal samples for formal quantification by the central laboratory resulted in a 58% reduction in laboratory microalbumin testing workload while retaining a high sensitivity (98.4%) and maximum specificity (100%). The POC results were in good agreement with the quantitative laboratory results. This test may therefore be used as a first-line screening tool that cuts central laboratory workload and accelerates the confirmation of microalbuminuria in diabetic patients.

Urine drugs of abuse testing at the point-of-care: clinical interpretation and programmatic considerations with specific reference to the Syva Rapid Test (SRT)

We evaluated a new point-of-care (POC) device for urine drugs of abuse (DOA) screening including appropriate clinical interpretation and potential benefits in a large academic medical center. Two hundred consecutive urine samples were tested using Syva Rapid Test (SRT) and existing laboratory methods (Syva EMIT II). Agreement between methods was acceptable with some considerations. Threshold concentration differences, drug interferences, and cross-reactivity profiles of the class-specific assays resulted in performance differences between the POC and central laboratory methods. Clinical interpretation of POC results requires an understanding of these issues as well as the limitations of urine testing. While urine-based screening is used in workplace testing and in a variety of clinical applications, quantitative blood measurements of some drugs (e.g. ethanol, acetaminophen, salicylate, ±tricyclic antidepressants) will remain important in the emergent setting. Performance of the SRT method takes approximately 10 min. Consequently, the major advantage over laboratory methods is rapid turnaround time. At the Massachusetts General Hospital, the most important application is for samples from the emergency department (about 1700/year). Each institution should assess its own needs and capabilities with regard to POC versus laboratory-based testing for DOA.

Status of point-of-care testing: promise, realities, and possibilities

Point-of-care testing (POCT) has evolved from the demand for analytical information more rapidly than is available from central laboratories. By bringing the analysis closer to the patient several process steps have been eliminated, facilitating a shorter time to result and faster management response with improved outcomes. Thus benefits include better therapeutic turnaround times, decreased blood loss as a result of reduced phlebotomy secondary to clinical improvement, and diminished resource utilization. These advantages depend on acceptable analytical performance in comparison with central laboratory methods and in relation to clinical criteria. Generally these requirements are met but there are problems particularly with atypical specimens. Outcomes and cost–benefit analyses have been difficult to perform and evaluate. Given the multitude of participants, quality assurance and program management are recognized as resource intensive. However, recognition of problem areas is driving continuous improvement and we envisage expansion of this paradigm.

Central Laboratory Analyses of Intact PTH Using Intraoperative Samples

During parathyroidectomy, chemiluminescent assays of intact parathyroid hormone levels in plasma are done by point-of-care methods. A rapid central-laboratory method has been developed that might be a more convenient and less expensive alternative. The new procedure was evaluated by assaying plasma from venous blood collected in EDTA tubes and comparing the results with those obtained by an accepted method. Samples were collected during surgery, transported to the central laboratory by pneumatic tube or courier, and analyzed immediately. Results were telephoned to the operating room. Turnaround time was equivalent to that of point-of-care methods. Results were diagnostically valuable and were provided at a fraction of the cost of bedside procedures.

Prediction of Bearing Capacity of Friction Piles in Soft Louisiana Soils by Cone Penetration Test

A comparison of four different methods for predicting the axial compression capacity of single piles using cone penetration test (CPT) results is presented. Nineteen pile load tests and parallel CPT soundings conducted close to the piles were identified and documented from the Louisiana Department of Transportation and Development archives. Piles with different sizes and lengths were investigated. The four prediction methods selected were the Schmertmann method, the de Ruiter and Beringen method, the French Central Bridge and Pavement Laboratory (LCPC) method, and the Tumay and Fakhroo method. An evaluation scheme was performed using these methods to assess their capability to reliably predict the axial compression capacity of piles installed in soft Louisiana soils. The predicted pile capacities obtained by the different methods were compared with the measured pile capacities obtained from pile load tests. Analysis of the results showed that the Schmertmann, de Ruiter and Beringen, and Tumay and Fakhroo methods predicted the ultimate compression capacities of piles installed in soft Louisiana soils with a reasonable accuracy. The LCPC method underpredicted the measured capacities of these piles.