3 research outputs found
Assessment of utility of daily patient results averages as adjunct quality control in a weekday-only satellite chemistry laboratory
ABSTRACT
Background:
Our department operates a weekday-only (8AM-5PM) satellite laboratory in an infusion center with a menu of 18 chemistry tests on a Roche c501 analyzer. We examined whether daily patient results averages (PRA) in this setting might be useful as a patient-based quality control (PBQC) adjunct to standard daily liquid quality control (LQC) measurements. First, we evaluated the reproducibility (coefficient of variation, CV) of daily PRAs for each analyte, and compared these to CVs of LQC. Second, for select analytes found to have relatively low PRA CVs, we evaluated the extent to which use of daily PRA measurements could improve detection of analytical errors when combined with LQC.
Methods:
Patient results data for approximately one month (21 weekdays) were obtained from the Sunquest laboratory information system. For calculation of patient results averages (PRA), qualifying results were restricted to those within the reference range for each analyte. PRA and standard deviation (S) of PRA across 21 days was calculated for each analyte. Coefficients of variation for PRA (CV-PRA) were compared to those observed for standard liquid quality control (LQC) measurements (CV-LQC). For those analytes for which CV-PRA was less than CV-LQC, we evaluated the potential advantage of addition of PRA to daily LQC. For each analyte, a presumed PRA shift was determined such that probability of detection (P) was 0.5 when using LQC alone (viz., using high LQC and low LQC measurements), according to criterion that at least one 1-2S deviation from mean was obtained. For this same PRA shift, P = 0.5 for LQC alone was compared to P obtained for LQC + PRA (viz., using high LQC, low LQC, and PRA measurements), according to the same criterion.
Results:
Across 21 days, the number of results per day per assay ranged from 23 ±4 (uric acid) to 75 ±21 (electrolytes). Qualifying results (results within the reference range) ranged from 70 ± 6 % (LDH) to 99 ± 1 % (Cl). Seven analytes had CV-PRA \u3c CV-LQC (analyte, CV%): albumin, 1.25%; Ca, 0.67%; Cl, 0.62%; CO2, 1.13%; creatinine, 3.44%; K, 1.14%; Na, 0.65%. The remainder did not meet this criterion: ALP, 3.7%; ALT, 5.2%; AST, 5.1%; BUN, 4.6%; glucose, 1.4%; LDH, 2.0%; Mg, 1.4%; P, 2.5%; protein, 0.9%; TBIL, 6.1%; uric acid, 4.3%. Among the seven analytes for which CV-PRA \u3c CV-LQC, probability (P) of shift detection by LQC for circumstances as described in Methods (LQC P = 0.5) was increased substantially by inclusion of PRA (analyte, shift in analyte concentration, P): CO2, ±1.07 mmol/L, 0.97; creatinine, ±0.099 mg/dL, 0.93; albumin, ±0.126 g/dL, 0.85; Ca, ±0.14 mg/dL, 0.80; K, ±0.097 mmol/L, 0.76; Cl, ±1.24 mmol/L, 0.74; Na, ±1.48 mmol/L, 0.68.
Conclusions:
For 7 analytes, daily PRA demonstrated CVs less than those for LQC. For these analytes, calculations demonstrated that daily PRA can increase probability of detection of small results shifts when used as an adjunct to LQC. Daily PRA is a simple and essentially cost-free form of PBQC that may be useful for certain analytes in part-time laboratory settings
Performance of Creatinine and Chloride on the epoc Analyzer
BACKGROUND
The epoc Blood Analysis System (Alere, Orlando, FL) performs blood gases, electrolytes, and metabolites using a Blood Gas Electrolyte and Metabolite (BGEM) Test Card panel on 92 uL of whole blood. The BGEM test card uses potentiometric sensors to measure sodium, potassium, ionized calcium, pH, pCO2; amperometric sensors to measure pO2, glucose, and lactate; and a conductometric sensor to measure hematocrit. Results are available in 3-10 minutes, depending upon the time between calibration and patient testing. TJUH implemented the epoc in its ICUs in 2012 to provide Point of Care (POC) results. Alere recently added creatinine and chloride sensors to its BGEM cartridge. At the request of our Emergency Department, we evaluated creatinine and chloride on the epoc.
Poster presented at: American Association for Clinical Chemistry Annual Scientific Meeting in Philadelphia PA.https://jdc.jefferson.edu/pacbposters/1005/thumbnail.jp
Activated Clotting Time (ACT): Comparison of the Hemochron Signature Elite and the Abbott i-STAT
BACKGROUND
ACT is commonly used for heparin anticoagulation monitoring during procedures including cardiopulmonary bypass surgery, coronary angioplasty, and interventional radiology. To prevent thrombosis, moderate to high levels of heparin anticoagulation are required. The Hemochron Signature Elite (HSE, Accriva Diagnostics, formerly ITC, San Diego, CA) was implemented at TJUH as a replacement for the older model Hemochron Response (Accriva/ITC Model HRS.110, San Diego, CA). Operating room (OR) perfusionists reported irreproducible high results using HSE that could not be explained clinically. In consideration of use of i-STAT analyzers (Abbott Point of Care, Princeton, NJ) as an alternative to HSE, we performed a comparison of ACT results as analyzed by HSE and i-STAT (Abbott Point of Care, Princeton, NJ) analyzers.
Poster presented at: American Association for Clinical Chemistry Annual Scientific Meeting in Philadelphia PA.https://jdc.jefferson.edu/pacbposters/1004/thumbnail.jp