Impact of Endogenous and Exogenous Interferences on Clinical Chemistry Parameters Measured on Blood Gas Analyzers.

BACKGROUND: The prevalence of hemolysis, icterus, and lipemia (HIL) was determined for residual whole blood specimens analyzed for clinical chemistry parameters on blood gas analyzers. The frequency and potential impact of exogenous interference from iodide, salicylate, and thiocyanate (metabolite of sodium nitroprusside) on analysis of whole blood chloride was also assessed. METHODS: Over an approximately two month period at an academic medical center, indices for HIL were determined on Roche cobas c502 analyzers for 1,986 residual whole blood specimens that had been previously analyzed for clinical chemistry parameters on Radiometer ABL90 FLEX blood gas analyzers. To examine exogenous interferences, retrospective analysis was performed over multiple years to ascertain whether patient samples analyzed for whole blood chloride were potentially affected by interference from iodide, salicylate, or thiocyanate. RESULTS: Some degree of hemolysis (defined as hemolysis index of greater than 60) was present in 9.7% of the whole blood specimens. Increasing rates of hemolysis were associated with higher whole blood potassium concentrations. Nearly 60% of specimens with potassium concentrations between 6.0 and 6.9 mEq/L had hemolysis indices of 100 or greater, and 75% of specimens with a potassium concentration of 7.0 mEq/L or greater were severely hemolyzed (hemolysis index of 300 or greater). In contrast to the hemolysis results, icterus and lipemia were determined to have minimal impact on patient results. For the exogenous interferences, we did not identify any patient samples where elevated salicylate levels or pharmaceutical iodide administration overlapped with whole blood chloride analysis (out of 75,887 and 169,229 total chloride measurements, respectively). We did, however, find that for patients receiving nitroprusside therapy in the inpatient setting, whole blood chloride concentrations were significantly higher during nitroprusside therapy [106.7 +/- 6.2 mEq/L (mean, SD)] compared to before or after nitroprusside therapy (103.1 +/- 7.7 mEq/L). CONCLUSIONS: In this analysis of whole blood specimens, hemolysis is a common interference and likely to introduce meaningful biases, as illustrated with potassium analysis. Icterus, lipemia, salicylate, and iodide appear unlikely to cause clinically significant bias. Nitroprusside therapy introduced a slight rise in whole blood chloride concentrations that probably has minimal clinical significance.

Impact of add-on laboratory testing at an academic medical center: a five year retrospective study.

BACKGROUND: Clinical laboratories frequently receive orders to perform additional tests on existing specimens ('add-ons'). Previous studies have examined add-on ordering patterns over short periods of time. The objective of this study was to analyze add-on ordering patterns over an extended time period. We also analyzed the impact of a robotic specimen archival/retrieval system on add-on testing procedure and manual effort. METHODS: In this retrospective study at an academic medical center, electronic health records from were searched to obtain all add-on orders that were placed in the time period of May 2, 2009 to December 31, 2014. RESULTS: During the time period of retrospective study, 880,359 add-on tests were ordered on 96,244 different patients. Add-on testing comprised 3.3 % of total test volumes. There were 443,411 unique ordering instances, leading to an average of 1.99 add-on tests per instance. Some patients had multiple episodes of add-on test orders at different points in time, leading to an average of 9.15 add-on tests per patient. The majority of add-on orders were for chemistry tests (78.8 % of total add-ons) with the next most frequent being hematology and coagulation tests (11.2 % of total add-ons). Inpatient orders accounted for 66.8 % of total add-on orders, while the emergency department and outpatient clinics had 14.8 % and 18.4 % of total add-on orders, respectively. The majority of add-ons were placed within 8 hours (87.3 %) and nearly all by 24 hours (96.8 %). Nearly 100 % of add-on orders within the emergency department were placed within 8 hours. The introduction of a robotic specimen archival/retrieval unit saved an average of 2.75 minutes of laboratory staff manual time per unique add-on order. This translates to 24.1 hours/day less manual effort in dealing with add-on orders. CONCLUSION: Our study reflects the previous literature in showing that add-on orders significantly impact the workload of the clinical laboratory. The majority of add-on orders are clinical chemistry tests, and most add-on orders occur within 24 hours of original specimen collection. Robotic specimen archival/retrieval units can reduce manual effort in the clinical laboratory associated with add-on orders.

Positive hepatitis B surface antigen tests due to recent vaccination: a persistent problem.

BACKGROUND: Hepatitis B virus (HBV) is a common cause of viral hepatitis with significant health complications including cirrhosis and hepatocellular carcinoma. Assays for hepatitis B surface antigen (HBsAg) are the most frequently used tests to detect HBV infection. Vaccination for HBV can produce transiently detectable levels of HBsAg in patients. However, the time course and duration of this effect is unclear. The objective of this retrospective study was to clarify the frequency and duration of transient HBsAg positivity following vaccination against HBV. METHODS: The electronic medical record at an academic tertiary care medical center was searched to identify all orders for HBsAg within a 17 month time period. Detailed chart review was performed to identify all patients who were administered HBV vaccine within 180 days prior to HBsAg testing and also to ascertain likely cause of weakly positive (grayzone) results. RESULTS: During the 17 month study period, 11,719 HBsAg tests were ordered on 9,930 patients. There were 34 tests performed on 34 patients who received HBV vaccine 14 days or less prior to HBsAg testing. Of these 34 patients, 11 had grayzone results for HBsAg that could be attributed to recent vaccination. Ten of the 11 patients were renal dialysis patients who were receiving HBsAg testing as part of routine and ongoing monitoring. Beyond 14 days, there were no reactive or grayzone HBsAg tests that could be attributed to recent HBV vaccination. HBsAg results reached a peak COI two to three days following vaccination before decaying. Further analysis of all the grayzone results within the 17 month study period (43 results out of 11,719 tests) revealed that only 4 of 43 were the result of true HBV infection as verified by confirmatory testing. CONCLUSIONS: Our study confirms that transient HBsAg positivity can occur in patients following HBV vaccination. The results suggest this positivity is unlikely to persist beyond 14 days post-vaccination. Our study also demonstrates that weakly positive HBsAg results often do not reflect actual HBV infection, underscoring the importance of confirmatory testing. This study also emphasizes that vaccination-induced HBsAg positives occur most commonly in hemodialysis patients.

Impact of Interfacing Near Point of Care Clinical Chemistry and Hematology Analyzers at Urgent Care Clinics at an Academic Health System.

BACKGROUND: Point-of-care (POC) testing equipment is commonly utilized in outpatient clinics. Our institution recently interfaced POC chemistry and hematology devices at two outpatient clinics via middleware software to the central electronic health record (EHR), facilitating a comparison of manual transcription versus automatic reporting via interface. This allowed for estimation of serious/obvious error rates and manual time savings. Additional goals were to develop autoverification rules and analyze broad trends of results in response to common clinician complaints on the POC testing. MATERIAL AND METHODS: Data were obtained from two satellite clinic sites providing both primary and urgent care within an academic health system. Interface of devices was accomplished via Instrument Manager middleware software and occurred approximately halfway through the 38 month retrospective timeframe. Laboratory results for three testing POC chemistry and hematology panels were extracted with EHR tools. RESULTS: Nearly 100,000 lab values were analyzed and revealed that the rate of laboratory values outside reference range was essentially unchanged before and after interface of POC testing devices (2.0-2.1%). Serious/obvious errors, while rare overall, declined significantly, with none recorded after the interface with autoverified results and only three related to manual edits of results that failed autoverification. Fewer duplicated test results were identified after the interface, most notably with the hematology testing. Anion gap values of less than zero were observed more frequently in POC device tests when compared to central laboratory tests and are attributed to a higher proportion of Cl values greater than 110 mEq/L and CO2 values greater than 30 mEq/L with POC results. Time savings of eliminating manual data entry were calculated to be 21.6 employee hours per month. CONCLUSIONS: In a switch from manual entry to automatic interface for POC chemistry and hematology, the most notable changes were reduction of serious/obvious errors and duplicate results. Significant time employee time savings highlight an additional benefit of instrument interfacing. Lastly, a difference between POC and central laboratory instruments is a higher rate of high Cl and CO2 values relative to the central laboratory.

Use of Middleware Data to Dissect and Optimize Hematology Autoverification.

BACKGROUND: Hematology analysis comprises some of the highest volume tests run in clinical laboratories. Autoverification of hematology results using computer-based rules reduces turnaround time for many specimens, while strategically targeting specimen review by technologist or pathologist. METHODS: Autoverification rules had been developed over a decade at an 800-bed tertiary/quarternary care academic medical central laboratory serving both adult and pediatric populations. In the process of migrating to newer hematology instruments, we analyzed the rates of the autoverification rules/flags most commonly associated with triggering manual review. We were particularly interested in rules that on their own often led to manual review in the absence of other flags. Prior to the study, autoverification rates were 87.8% (out of 16,073 orders) for complete blood count (CBC) if ordered as a panel and 85.8% (out of 1,940 orders) for CBC components ordered individually (not as the panel). RESULTS: Detailed analysis of rules/flags that frequently triggered indicated that the immature granulocyte (IG) flag (an instrument parameter) and rules that reflexed platelet by impedance method (PLT-I) to platelet by fluorescent method (PLT-F) represented the two biggest opportunities to increase autoverification. The IG flag threshold had previously been validated at 2%, a setting that resulted in this flag alone preventing autoverification in 6.0% of all samples. The IG flag threshold was raised to 5% after detailed chart review; this was also the instrument vendor's default recommendation for the newer hematology analyzers. Analysis also supported switching to PLT-F for all platelet analysis. Autoverification rates increased to 93.5% (out of 91,692 orders) for CBC as a panel and 89.8% (out of 11,982 orders) for individual components after changes in rules and laboratory practice. CONCLUSIONS: Detailed analysis of autoverification of hematology testing at an academic medical center clinical laboratory that had been using a set of autoverification rules for over a decade revealed opportunities to optimize the parameters. The data analysis was challenging and time-consuming, highlighting opportunities for improvement in software tools that allow for more rapid and routine evaluation of autoverification parameters.

Data on length of parathyroidectomy surgery and intraoperative parathyroid hormone (PTH) assay turnaround times following a switch in the location for intraoperative PTH testing from near point-of-care to central laboratory.

Intraoperative monitoring of parathyroid hormone (PTH) is commonly used during parathyroidectomies. There are a number of practical challenges in achieving rapid turnaround time (TAT) for intraoperative PTH testing, whether the testing is performed point-of-care, near point-of-care, or in a central clinical laboratory. In the related research article, we analyzed a decade of data from 3025 intraoperative PTH tests on 897 unique patients. Of these, 1787 tests on 514 unique patients (375 female, 139 male) occurred while intraoperative PTH measurement was done as near point-of-care testing; the remaining 1238 tests on 383 unique patients (282 female, 101 male) occurred after a switch to intraoperative PTH measurement by the hospital central laboratory. The data in this article provides the patient age, gender, location of surgery (main operating rooms vs. ambulatory surgery center), incision to close time for surgery, and operation start to end times. For the central laboratory testing, additional data are provided for the intraoperative PTH TAT. The analyzed data is provided in the supplementary tables included in this article. Plots of operation start and end times are also included. The dataset reported is related to the research article entitled "Evaluation of Switch from Satellite Laboratory to Central Laboratory for Testing of Intraoperative Parathyroid Hormone" [D. Jacob, G. Lal, D.R. Voss, T. Bebber, S.R. David, J. Kulhavy, S.L. Sugg, A.E. Merrill, M.D. Krasowski, Evaluation of Switch from Satellite Laboratory to Central Laboratory for Testing of Intraoperative Parathyroid Hormone, Pract. Lab. Med. (2020) 22: e00176] [1].

Evaluation of switch from satellite laboratory to central laboratory for testing of intraoperative parathyroid hormone.

OBJECTIVES: The aim of this study was to evaluate testing turnaround time (TAT) and incision to close time in parathyroid surgeries before and after switching intraoperative parathyroid hormone (PTH) testing from a near point of care location to a central clinical laboratory. DESIGN AND METHODS: This retrospective study covered a ten-year period. Both testing locations used the same Roche Diagnostics PTH immunoassay but on different analyzers. The predominant site for surgeries was the main operating rooms (ORs) in an adjacent building, with a limited number of parathyroid surgeries performed at a more distant ambulatory surgery center (ASC). Under ideal conditions, TAT for near point-of-care testing was 20 â€‹min, although multiple factors could increase TAT. Incision to close time from the electronic health record was used to define time of surgery. RESULTS: A total of 897 unique patients were identified for which 3031 orders for intraoperative PTH were placed (383 unique patients and 1244 orders after switch in testing site). The average total TAT times for testing (mean â€‹± â€‹SD) in the central laboratory were 23.9 â€‹± â€‹16.0 â€‹min (median, 22 â€‹min) for all specimens, 22.8 â€‹± â€‹7.9 â€‹min (median, 21 â€‹min) for main OR specimens, and 26.4 â€‹± â€‹7.1 â€‹min (median, 25 â€‹min) for ASC specimens. Incision to close time for parathyroidectomies showed decreases in mean, median, and standard deviation following testing change. CONCLUSIONS: Surgery time for parathyroidectomies may remain consistent or decrease if intraoperative PTH testing is moved from a near point of care to a central laboratory.

Impact of Daylight Saving Time on the Clinical Laboratory.

Daylight saving time is a practice in some countries and local regions to set clocks forward (typically 1 hour) during the longer days of summer and back again in autumn. Time changes resulting from daylight saving time have the potential to impact clinical laboratory instruments, computer interfaces, and information systems. We analyzed turnaround time data for an academic medical center clinical laboratories (chemistry, hematology, blood gas analyzer, and transfusion medicine), examining how turnaround time was impacted by the daylight saving time shifts in 2017. We also determined whether the daylight saving time shift on November 5, 2017 ("fall back" by 1 hour) resulted in any "absurd" time combinations such as a receipt time occurring "before" a normally later time such as final result. We also describe challenges resulting from daylight saving time changes over a 5-year period. The only significant impact on turnaround time was for clinical chemistry samples during the autumn daylight saving time change, but the overall impact was low. Four instances of absurd time combinations occurred in the autumn time change with only a transfusion medicine example resulting in an interface error (a Type and Screen resulted "before" receipt in laboratory). Over a 5-year period, other daylight saving time impacts included problems of reestablishing interface to instruments, inadvertent discrepancies in manual time changes at different points of the core laboratory automation line, and time change errors in instruments with older operating systems lacking patches that updated daylight saving time rules after 2007. Clinical laboratories should be aware that rare problems may occur due to issues with daylight saving time changes.

Frequency and causes of lipemia interference of clinical chemistry laboratory tests.

OBJECTIVES: The aims of this study were to identify the causes of severe lipemia in an academic medical center patient population and to determine the relationship between lipemia and hemolysis. DESIGN AND METHODS: Retrospective study was done on the data from the core clinical laboratory at an academic medical center. Lipemic indices were available for all chemistry specimens analyzed over a 16-month period (n=552,029 specimens) and for serum/plasma triglycerides concentrations ordered for clinical purposes over a 16-year period (n=393,085 specimens). Analysis was performed on Roche Diagnostics cobas 8000 analyzers. Extensive chart review was done for all specimens with lipemic index greater than 500 (severely lipemic) and for all specimens with serum/plasma triglycerides greater than 2000 mg/dL. We also determined the relationship between lipemia and hemolysis. RESULTS: The most frequent suspected causes of very high lipemic index (>500) were found to be lipid-containing intravenous infusions (54.4% of total; fat emulsions for parenteral nutrition - 47%; propofol -7.4%) and diabetes mellitus (25% of total, mainly type 2). The most frequent suspected causes of very elevated serum/plasma triglycerides (>2000 mg/dL) was diabetes mellitus (64%, mainly type 2) and hyperlipidemia (16.9%). The frequency of hemolysis increased with increasing lipemic index. CONCLUSIONS: Intravenous lipid infusions and type 2 diabetes were the most common causes of severe lipemia in this study at an academic medical center. Given that iatrogenic factors are the most common cause of severe lipemia, education and intervention may be helpful in reducing frequency of severe lipemia in patient specimens.

Use of a Rapid Ethylene Glycol Assay: a 4-Year Retrospective Study at an Academic Medical Center.

Ethylene glycol (EG) is a common cause of toxic ingestions. Gas chromatography (GC)-based laboratory assays are the gold standard for diagnosing EG intoxication. However, GC requires specialized instrumentation and technical expertise that limits feasibility for many clinical laboratories. The objective of this retrospective study was to determine the utility of incorporating a rapid EG assay for management of cases with suspected EG poisoning. The University of Iowa Hospitals and Clinics core clinical laboratory adapted a veterinary EG assay (Catachem, Inc.) for the Roche Diagnostics cobas 8000 c502 analyzer and incorporated this assay in an osmolal gap-based algorithm for potential toxic alcohol/glycol ingestions. The main limitation is that high concentrations of propylene glycol (PG), while readily identifiable by reaction rate kinetics, can interfere with EG measurement. The clinical laboratory had the ability to perform GC for EG and PG, if needed. A total of 222 rapid EG and 24 EG/PG GC analyses were documented in 106 patient encounters. Of ten confirmed EG ingestions, eight cases were managed entirely with the rapid EG assay. PG interference was evident in 25 samples, leading to 8 GC analyses to rule out the presence of EG. Chart review of cases with negative rapid EG assay results showed no evidence of false negatives. The results of this study highlight the use of incorporating a rapid EG assay for the diagnosis and management of suspected EG toxicity by decreasing the reliance on GC. Future improvements would involve rapid EG assays that completely avoid interference by PG.

Prevalence and Clinical Utility of "Incidental" Critical Values Resulting From Critical Care Laboratory Testing.

OBJECTIVE: Panels of clinical laboratory testing may generate "incidental" critical values from unordered parameters. Existing regulations do not clearly delineate guidelines for handling incidental critical values. The objective of this study was to examine the patterns and clinical utility of incidental critical values at 2 critical care laboratories within an academic medical center. METHODS: In this retrospective study, the electronic health record and laboratory information system were reviewed for incidental critical results obtained from blood gas analyzer analysis of whole blood specimens between November 2010 and August 2014. RESULTS: Within the retrospective time period, 9,092 incidental critical results were documented, of which only 11.8% were added to the "parent" order following clinical notification. Incidental critical results frequently occurred in patients who had recent critical values for the same parameter. CONCLUSION: In this study, at an academic medical center, incidental critical values associated with blood gas analyzers were added on at a low rate and often provided redundant information. Relative to the manual effort involved in care providers' notification and documentation of results, incidental critical values appear to have low clinical utility.

Implementation of Epic Beaker Clinical Pathology at an academic medical center.

BACKGROUND: Epic Beaker Clinical Pathology (CP) is a relatively new laboratory information system (LIS) operating within the Epic suite of software applications. To date, there have not been any publications describing implementation of Beaker CP. In this report, we describe our experience in implementing Beaker CP version 2012 at a state academic medical center with a go-live of August 2014 and a subsequent upgrade to Beaker version 2014 in May 2015. The implementation of Beaker CP was concurrent with implementations of Epic modules for revenue cycle, patient scheduling, and patient registration. METHODS: Our analysis covers approximately 3 years of time (2 years preimplementation of Beaker CP and roughly 1 year after) using data summarized from pre- and post-implementation meetings, debriefings, and the closure document for the project. RESULTS: We summarize positive aspects of, and key factors leading to, a successful implementation of Beaker CP. The early inclusion of subject matter experts in the design and validation of Beaker workflows was very helpful. Since Beaker CP does not directly interface with laboratory instrumentation, the clinical laboratories spent extensive preimplementation effort establishing middleware interfaces. Immediate challenges postimplementation included bar code scanning and nursing adaptation to Beaker CP specimen collection. The most substantial changes in laboratory workflow occurred with microbiology orders. This posed a considerable challenge with microbiology orders from the operating rooms and required intensive interventions in the weeks following go-live. In postimplementation surveys, pathology staff, informatics staff, and end-users expressed satisfaction with the new LIS. CONCLUSIONS: Beaker CP can serve as an effective LIS for an academic medical center. Careful planning and preparation aid the transition to this LIS.

Autoverification in a core clinical chemistry laboratory at an academic medical center.

BACKGROUND: Autoverification is a process of using computer-based rules to verify clinical laboratory test results without manual intervention. To date, there is little published data on the use of autoverification over the course of years in a clinical laboratory. We describe the evolution and application of autoverification in an academic medical center clinical chemistry core laboratory. SUBJECTS AND METHODS: At the institution of the study, autoverification developed from rudimentary rules in the laboratory information system (LIS) to extensive and sophisticated rules mostly in middleware software. Rules incorporated decisions based on instrument error flags, interference indices, analytical measurement ranges (AMRs), delta checks, dilution protocols, results suggestive of compromised or contaminated specimens, and 'absurd' (physiologically improbable) values. RESULTS: The autoverification rate for tests performed in the core clinical chemistry laboratory has increased over the course of 13 years from 40% to the current overall rate of 99.5%. A high percentage of critical values now autoverify. The highest rates of autoverification occurred with the most frequently ordered tests such as the basic metabolic panel (sodium, potassium, chloride, carbon dioxide, creatinine, blood urea nitrogen, calcium, glucose; 99.6%), albumin (99.8%), and alanine aminotransferase (99.7%). The lowest rates of autoverification occurred with some therapeutic drug levels (gentamicin, lithium, and methotrexate) and with serum free light chains (kappa/lambda), mostly due to need for offline dilution and manual filing of results. Rules also caught very rare occurrences such as plasma albumin exceeding total protein (usually indicative of an error such as short sample or bubble that evaded detection) and marked discrepancy between total bilirubin and the spectrophotometric icteric index (usually due to interference of the bilirubin assay by immunoglobulin (Ig) M monoclonal gammopathy). CONCLUSIONS: Our results suggest that a high rate of autoverification is possible with modern clinical chemistry analyzers. The ability to autoverify a high percentage of results increases productivity and allows clinical laboratory staff to focus attention on the small number of specimens and results that require manual review and investigation.