• 1.

    O'Brien MA. Diabetic emergencies in small animals. Vet Clin North Am Small Anim Pract 2010;40:317333.

  • 2.

    Schaer M. Therapeutic approach to electrolyte emergencies. Vet Clin North Am Small Anim Pract 2008;38:513533.

  • 3.

    Gonzalez AL, Waddell LS. Blood gas analyzers. Top Companion Anim Med 2016;31:2734.

  • 4.

    Flatland B, Freeman KP, Vap LM, et al. ASVCP guidelines: quality assurance for point-of-care testing in veterinary medicine. Vet Clin Pathol 2013;42:405423.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5.

    Stat Profile Prime Plus VET Critical Care Analyzer. Available at: www.novabio.us/prime-plus-vet/index.php. Accessed Jun 27, 2019.

  • 6.

    Flatland B, Freeman KP, Friedrichs KR, et al. ASVCP quality assurance guidelines: control of general analytical factors in veterinary laboratories. Vet Clin Pathol 2010;39:264277.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7.

    Tate JR, Sikaris KA, Jones GRD, et al. Harmonising adult and paediatric reference intervals in Australia and New Zealand: an evidence-based approach for establishing a first panel of chemistry analytes. Clin Biochem Rev 2014;35:213235.

    • Search Google Scholar
    • Export Citation
  • 8.

    Langston C. Managing fluid and electrolyte disorders in kidney disease. Vet Clin North Am Small Anim Pract 2017;47:471490.

  • 9.

    Tate JR, Yen T, Jones GRD. Transference and validation of reference intervals. Clin Chem 2015;61:10121015.

  • 10.

    Friedrichs KR, Harr KE, Freeman KP, et al. ASVCP reference interval guidelines: determination of de novo reference intervals in veterinary species and other related topics. Vet Clin Pathol 2012;41:441453.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11.

    Bell R, Harr K, Rishniw M, et al. Survey of point-of-care instrumentation, analysis, and quality assurance in veterinary practice. Vet Clin Pathol 2014;43:185192.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 12.

    Harr KE, Flatland B, Nabity M, et al. ASVCP guidelines: allowable total error guidelines for biochemistry. Vet Clin Pathol 2013;42:424436.

  • 13.

    Budak YU, Huysal K, Polat M. Use of a blood gas analyzer and a laboratory autoanalyzer in routine practice to measure electrolytes in intensive care unit patients. BMC Anesthesiol 2012;12:17.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14.

    Jain A, Subhan I, Joshi M. Comparison of the point-of-care blood gas analyzer versus the laboratory auto-analyzer for the measurement of electrolytes. Int J Emerg Med 2009;2:117120.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15.

    Uyanik M, Sertoglu E, Kayadibi H, et al. Comparison of blood gas, electrolyte and metabolite results measured with two different blood gas analyzers and a core laboratory analyzer. Scand J Clin Lab Invest 2015;75:97105.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16.

    Dimeski G, Morgan TJ, Presneill JJ, et al. Disagreement between ion selective electrode direct and indirect sodium measurements: estimation of the problem in a tertiary referral hospital. J Crit Care 2012;27:326.e9326.e16.

    • Search Google Scholar
    • Export Citation
  • 17.

    Thoresen SI, Havre GN, Morberg H, et al. Effects of storage time on chemistry results from canine whole blood, heparinized whole blood, serum and heparinized plasma. Vet Clin Pathol 1992;21:8894.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18.

    Flatland B, Camus MS, Baral RM. Analytical quality goals—a review. Vet Clin Pathol 2018;47:527538.

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Evaluation of two benchtop blood gas analyzers for measurement of electrolyte concentrations in venous blood samples from dogs

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  • 1 From the Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biological Sciences, Texas A&M University, College Station, TX 77843
  • | 2 From the Department of Veterinary Patho-biology, College of Veterinary Medicine and Biological Sciences, Texas A&M University, College Station, TX 77843

Abstract

OBJECTIVE

To assess agreement between 2 benchtop blood gas analyzers developed by 1 manufacturer (BGA 1 and BGA 2 [a newer model with reduced maintenance requirements]) and a reference chemistry analyzer for measurement of electrolyte (sodium, chloride, and potassium) in blood samples from dogs.

ANIMALS

17 healthy staff- and student-owned dogs and 23 client-owned dogs admitted to an emergency and intensive care service.

PROCEDURES

Blood collected by venipuncture was placed in lithium heparin–containing tubes. Aliquots were analyzed immediately with each BGA. Samples were centrifuged, and plasma was analyzed with the reference analyzer. Results for each BGA were compared with results for the reference analyzer by Passing-Bablok regression analysis. Percentage differences between BGA and reference analyzer results were compared with published guidelines for total allowable error.

RESULTS

Proportional bias was detected for measurement of chloride concentration (slope, 0.7; 95% CI, 0.7 to 0.8), and constant positive bias was detected for measurement of chloride (y-intercept, 34, mmol/L; 95% CI, 16.9 to 38 mmol/L) and potassium (y-intercept, 0.1 mmol/L; 95% CI, 0.1 to 0.2 mmol/L) concentrations with BGA 1. There was no significant bias for measurement of potassium or chloride concentration with BGA 2 or sodium concentration with either BGA. Differences from the reference analyzer result exceeded total allowable error guidelines for ≥ 1 sample/analyte/BGA, but median observed measurement differences between each BGA and the reference analyzer did not.

CONCLUSIONS AND CLINICAL RELEVANCE

Good agreement with reference analyzer results was found for measurement of the selected electrolyte concentrations in canine blood samples with each BGA.

Abstract

OBJECTIVE

To assess agreement between 2 benchtop blood gas analyzers developed by 1 manufacturer (BGA 1 and BGA 2 [a newer model with reduced maintenance requirements]) and a reference chemistry analyzer for measurement of electrolyte (sodium, chloride, and potassium) in blood samples from dogs.

ANIMALS

17 healthy staff- and student-owned dogs and 23 client-owned dogs admitted to an emergency and intensive care service.

PROCEDURES

Blood collected by venipuncture was placed in lithium heparin–containing tubes. Aliquots were analyzed immediately with each BGA. Samples were centrifuged, and plasma was analyzed with the reference analyzer. Results for each BGA were compared with results for the reference analyzer by Passing-Bablok regression analysis. Percentage differences between BGA and reference analyzer results were compared with published guidelines for total allowable error.

RESULTS

Proportional bias was detected for measurement of chloride concentration (slope, 0.7; 95% CI, 0.7 to 0.8), and constant positive bias was detected for measurement of chloride (y-intercept, 34, mmol/L; 95% CI, 16.9 to 38 mmol/L) and potassium (y-intercept, 0.1 mmol/L; 95% CI, 0.1 to 0.2 mmol/L) concentrations with BGA 1. There was no significant bias for measurement of potassium or chloride concentration with BGA 2 or sodium concentration with either BGA. Differences from the reference analyzer result exceeded total allowable error guidelines for ≥ 1 sample/analyte/BGA, but median observed measurement differences between each BGA and the reference analyzer did not.

CONCLUSIONS AND CLINICAL RELEVANCE

Good agreement with reference analyzer results was found for measurement of the selected electrolyte concentrations in canine blood samples with each BGA.

Introduction

Point-of-care testing is invaluable when submitting samples to a reference laboratory would create an unacceptable delay, as is the case for detection and monitoring of life-threatening electrolyte disturbances.1,2 In a veterinary primary care or emergency setting, resources to support in-house testing are often limited, and portable instruments that rely on single-use cartridges are popular, as they are perceived as easy to use and maintain.3 Unfortunately, the fixed cost per cartridge means there is no economy of scale, so for hospitals where clinicopathologic tests are performed frequently, larger BGAs with multiuse reagents can improve cost-effectiveness.3

Benchtop instruments typically require more maintenance and quality-assurance protocols than cartridge-based analyzers, increasing demands on the clinical team.3,4 One manufacturer provides 2 veterinary benchtop BGAs that analyze multiple samples in a single run; the newer of these 2 analyzers has reduced maintenance requirements, owing in part to the sensors for 18 analytes being combined into a single disposable sensor card that is replaced once every 28 to 30 days.5 The newer product also uses a multiwavelength optical system to generate cooximetry results without erythrocyte lysis, thus avoiding the cleaning and deproteinizing requirements associated with sample lysis.5

Before relying on a new analyzer for assessment of patient samples, it is important to determine agreement for analyte measurements with those obtained by use of a reference method.6 Such method agreement studies quantify bias, defined as a systematic error that may occur consistently across the analytic range (ie, constant bias) or may alter with analyte concentration (ie, proportional bias).6 Evaluation of bias is particularly important when published decision limits are used to guide diagnostic and therapeutic decisions, as is common in the management of electrolyte disturbances, or when it is desirable to use a common reference interval across multiple analyzers.1,2,7,8 De novo reference interval generation is a complex and expensive process rarely performed by veterinary practitioners, but when methods agree well, it is likely that a more straightforward transference study will be sufficient to confirm that an already established reference interval can be used for the new analyzer.9,10,11 At its simplest, a transference study involves comparing results for 20 healthy animals with a reference interval established in another population for the same species or by use of another instrument or method. If ≤ 2 results are outside the established reference interval, the new instrument is considered valid for use in the setting for which it was tested.9

The purpose of the study reported here was to assess agreement for measurement of sodium, potassium, and chloride concentrations in canine blood samples between 2 benchtop BGAs and a reference chemistry analyzer. These 3 analytes were chosen for investigation because changes in sodium, potassium, and chloride concentrations help to guide IV fluid therapy in an emergency setting and can be readily measured by both blood gas and reference chemistry analyzers. We aimed to compare the results provided by each device with results provided by a reference laboratory analyzer for analysis of plasma derived from the same samples.

Materials and Methods

Animals

A sample of 17 healthy dogs owned by Texas A&M University Veterinary Medical Teaching Hospital staff or veterinary students and 23 client-owned dogs that were admitted to the emergency and intensive care service of the same facility between May 17, 2018, and March 1, 2019, were included in the study. The total sample size of 40 dogs was selected because this is the minimum number of animals recommended for method comparison studies by the ASVCP.6

Healthy dogs were recruited by invitation from the study investigators. These dogs were deemed healthy on the basis of complete physical examination. For client-owned dogs admitted to the hospital, enrollment in the study was at the discretion of the attending clinician. No dogs were excluded because of disease process or treatment regimen. All dog owners provided informed consent for study enrollment. The study protocol was approved by the Institutional Animal Care and Use Committee of Texas A&M University.

Sample collection and analysis

Purpose-drawn blood samples (3 mL) were obtained by routine venipuncture, with collection site and needle gauge at the discretion of the veterinarian or technician who collected the sample. Immediately after collection, blood was transferred to a lithium heparin–containing tubea and briefly mixed by inverting several times.

Immediately after transfer to the tube, whole blood was analyzed with 2 benchtop BGAs designed for veterinary use (BGA 1b [a benchtop analyzer already in use at the authors' facility] and BGA 2c). Envelope draw was used to randomly determine the order of BGA use for each sample. Within 20 minutes after collection, samples were centrifuged, and heparinized plasma was collected. Sodium, chloride, and potassium concentrations in plasma were immediately analyzed with an in-house reference chemistry analyzer.d Both BGAs and the reference analyzer used direct potentiometry for measurement of electrolyte concentrations. Throughout the study period, all instruments underwent regular quality control and routine maintenance as directed by the respective manufacturers.

Statistical analysis

Passing-Bablok regression was used to investigate whether systematic error was present in measurements obtained with either BGA by comparing the results for BGA 1 and BGA 2 with the results obtained by use of the reference chemistry analyzer. Significant proportional bias was considered present if the 95% CI for the slope of the regression line did not include 1, and significant constant bias was considered present if the 95% CI for the y-intercept did not overlap 0.6

To estimate the clinical relevance of bias, the investigators considered the range of concentrations for each analyte likely to be encountered in canine patients and selected 3 concentrations, including a concentration within, above, and below the in-house reference intervals for both BGA 1 and the reference chemistry analyzer. Estimated (predicted) results at these concentrations were calculated from the regression equation for each BGA versus the reference analyzer, and the percentage difference between the theoretical and predicted result was determined with the following equation: ([Predicted BGA result − theoretical reference analyzer result]/theoretical reference analyzer result) × 100.

Additionally, for each sample, observed percentage differences between the BGA and reference analyzer were calculated with the following equation: ([BGA result − reference analyzer result]/reference analyzer result) × 100. Observed and predicted percentage differences were compared with the ASVCP guidelines for TEa,12 and the proportion of samples for which the observed differences exceeded TEa was calculated. Agreement was considered good if the median difference was less than the TEa for the analyte. Statistical analysis was performed with commercially available statistical software.e

Results

The median age of the 40 dogs in the study was 4 years (range, 1 to 14 years). Thirteen dogs were spayed females, 3 were sexually intact females, 21 were neutered males, and 3 were sexually intact males. There were 14 mixed-breed dogs, 6 Golden Retrievers, 4 Labrador Retrievers, 2 Bassett Hounds, 2 American Pit Bull Terriers, and 1 each of the following breeds: American Eskimo Dog, Chihuahua, Dachshund, Fox Terrier, German Shorthaired Pointer, Miniature Schnauzer, Pomeranian, Great Pyrenees, Shetland Sheepdog, Shih Tzu, Standard Poodle, and Weimaraner. For the 23 clinical patients, diagnoses were gastrointestinal disease (n = 6), toxicosis or envenomation (3), bacterial infection or sepsis (2), cardiac disease (2), renal disease (2), trauma or orthopedic injury (4), diabetes mellitus (1), hemangiosarcoma (1), heatstroke (1), and meningoencephalitis of unknown origin (1). All results were within the reportable range for all 3 analyzers.

The results of Passing-Bablok regression analysis indicated that BGA 1 had proportional bias for measurement of chloride concentration and constant positive bias for measurement of chloride and potassium concentrations (Table 1); the regression plots are provided (Supplementary Figure S1, available at: avmajournals.avma.org/doi/suppl/10.2460/ajvr.82.2.105). No constant or proportional biases were detected for BGA 2.

Table 1

Analyzer data and results of Passing-Bablok regression analysis for detection of systematic error (bias) in a study to assess agreement between each of 2 benchtop BGAs (BGA 1b and BGA 2c) and a reference chemistry analyzerd for measurement of selected electrolyte concentrations in blood samples from dogs.

ElectrolyteReference intervalAnalyzerMeasurement (median [range])Passing-Bablok regression analysis
Reference analyzerBGA 1Slope (95% CI)y-intercept (95% CI)
Chloride (mmol/L)107 to 116110 to 116Reference analyzer114 (87 to 125)
BGA 1114 (96 to 121)0.7 (0.7 to 0.8)*34 (16.9 to 38)
BGA 2113 (93 to 120)0.8 (0.6 to 1.0)28 (−1.0 to 43)
Potassium (mmol/L)3.3 to 4.63.9 to 4.4Reference analyzer4.1 (3.6 to 5.0)
BGA 14.3 (3.7 to 5.3)1.0 (1.0 to 1.0)0.1 (0.1 to 0.2)
BGA 24.2 (3.4 to 4.9)1.0 (0.9 to 1.0)0.1 (0.0 to 0.6)
Sodium (mmol/L)139 to 147146 to 153Reference analyzer145 (129 to 157)
BGA 1146 (132 to 156)0.9 (0.7 to 1.0)17 (0.0 to 45)
BGA 2148 (130 to 157)1.0 (0.8 to 1.3)2.0 (−47 to 30)

Venous blood samples were collected from 40 animals (17 healthy dogs and 23 client-owned dogs admitted to an intensive care service) at 1 facility and transferred into lithium heparin–containing tubes; each sample was mixed and immediately tested with each BGA (in randomly assigned order), then plasma was collected for immediate testing with the reference analyzer. Previously established reference analyzer and BGA 1 reference intervals at the institution where the study was performed are shown to aid assessment of the clinical relevance of the range of concentrations analyzed.

Proportional bias is present (95% CI for the slope does not include 1).

Constant bias is present (95% CI for the y-intercept does not include 0).

— = Not applicable.

On the basis of regression equations, the predicted percentage differences from reference analyzer values were small for both BGAs at selected theoretical concentrations within, below, and above the reference chemistry analyzer and BGA 1 reference intervals for each electrolyte (Table 2). The observed median measurement differences between each BGA and the reference analyzer were smaller than the ASVCP TEa for all 3 electrolytes, meeting our requirement for good agreement (Table 3). However, this difference exceeded the TEa for ≥ 1 sample/analyte/BGA (range, 1 to 9).

Table 2

Predicted percentage differences in measurements between each BGA and the reference analyzer in Table 1 at theoretical concentrations of each electrolyte above, within, and below the previously established reference intervals for BGA 1 and the reference chemistry analyzer.

Result classification for theoretical sampleElectrolyteTheoretical reference analyzer result (mmol/L)Predicted difference (%)
BGA 1BGA 2
Below reference intervalChloride10043
Potassium 3.033
Sodium13022
Within reference intervalChloride11200
Potassium 4.033
Sodium14711
Above reference intervalChloride120−2−2
Potassium 6.022
Sodium160−0.61

Predicted differences from the reference analyzer result were calculated from the Passing-Bablok regression equation. The theoretical reference analyzer values were selected by the investigators on the basis of the range of values likely to be encountered clinically.

Table 3

Median (range) observed percentage differences in measurements between each BGA and the reference analyzer in Table 1, compared with the ASVCP TEa12 for the electrolytes of interest.

ElectrolyteTEa (%%)AnalyzerObserved difference (%)Proportion with observed exceeding TEa
Chloride5%BGA 11 (−6 to 7)2/40
BGA 2−1 (−5 to 10)1/40
Potassium10% (below reference interval)BGA 13 (3)0/2
BGA 23 (3)0/3
5% (within or above reference interval)BGA 10 (−13 to 5)3/38
BGA 22 (−2 to 9)9/37
Sodium5%BGA 11 (−5 to 7)2/40
BGA 21 (−3 to 7)1/40

Discussion

The present study found no significant proportional or constant biases for measurements of chloride, potassium, or sodium concentrations in canine blood samples with BGA 2, compared with measurements of these electrolyte concentrations in plasma from the same samples by use of a reference chemistry analyzer. In contrast, BGA 1, an earlier model of benchtop analyzer produced by the same manufacturer, had significant constant and proportional biases for measurement of chloride concentration and significant constant bias for measurement of potassium concentration. However, for both analyzers, predicted differences between the BGA and reference chemistry results as calculated from the regression equation were small and unlikely to be clinically relevant. This suggested that BGA 2 is an acceptable alternative to BGA 1 for diagnosis and monitoring of electrolyte disorders in dogs.

Good agreement between each BGA and the reference analyzer for measurement of electrolyte concentrations was expected, as all 3 devices used the direct potentiometry method for these measurements. In previous studies13,14,15 that found poor agreement between BGAs and a reference method for electrolyte measurements, investigators generally compared point-of-care analyzers that use direct potentiometry with reference analyzers that use an indirect method. Although there may be differences in the performance of, for example, the specific electrodes used in different instruments that employ direct potentiometry, it is predictable that there will be greater differences between direct and indirect potentiometry methods.16 Indirect potentiometry, which involves sample dilution, is susceptible to interferences from nonaqueous plasma components such as proteins and lipids.16 Nonaqueous components do not influence direct potentiometry; therefore, conditions such as hyperproteinemia will not cause pseudohyponatremia results in samples analyzed by any of the devices used in the present study.16 It is important to note that the number of samples with marked electrolyte imbalances in the present study was small. Results predicted on the basis of the regression analysis should therefore be interpreted with caution when these were extrapolated beyond the range of values found for the study sample, as for assessment of predicted differences at our selected low potassium and high potassium and sodium concentrations. Future studies that focus on samples with markedly abnormal concentrations of these electrolytes would provide a more accurate assessment of systematic error at the extremes of the analytic ranges.

It should also be emphasized that the present study was focused on agreement between results generated by the BGAs and reference analyzer. Our regression analysis results therefore provide estimates of bias (also termed systematic error).6 Evaluation of bias is important for determining whether reference intervals, clinical decision limits, and critical values can be transferred between instruments.7,9 However, random error, sometimes termed imprecision, also contributes to analytic error.12 For each electrolyte measured with the 2 BGAs, there was a small number of samples for which observed differences between the BGA and reference analyzer exceeded the ASVCP TEa guidelines.12 Considering that imprecision creates sporadic, unpredictable errors, it is likely to have contributed to these occasional larger errors. Preanalytic problems, such as delayed plasma separation, sample contamination (eg, from K2EDTA), or interferences (eg, hemolysis in certain breeds), could also have contributed to sporadic errors, although our sample-handling protocol was designed to minimize such effects.17 Ideally, sample analysis would have been repeated to verify the results, but because the BGAs required whole blood and the reference chemistry analyzer required plasma, this was not feasible.

When discussing TEa, it is important to consider that in a veterinary context, these are guidelines rather than regulatory requirements. The ASVCP guidelines were developed by an expert panel of veterinary clinical pathologists and clinicians, and the TEas reflect the maximum error considered clinically acceptable in most veterinary settings.12 However, it is recognized that quality goals may need to be modified in some situations.18 Point-of-care testing is often employed in a triage setting to allow rapid identification of abnormalities that need to be rapidly addressed. Quickly recognizing electrolyte disturbances before initiating fluid therapy may be more clinically important than measuring concentrations to the level of accuracy achievable in a reference laboratory. For many clinicians who use point-of-care devices, some relaxation of TEa targets may be acceptable, particularly if abnormal results can alter plans for resuscitative treatment or trigger confirmatory testing with a reference method.

Acknowledgments

Nova Biomedical provided consumables, trained the investigators, performed maintenance, and loaned the Stat Profile Prime+ Vet instrument for the duration of the study and funded clinical pathology testing. The manufacturer approved a study protocol before the initiation of the study and viewed but did not edit the manuscript prior to submission.

Results were presented in abstract form at the 25th International Veterinary Emergency and Critical Care Symposium, Washington, DC, September 2019.

Abbreviations

ASVCP

American Society for Veterinary Clinical Pathology

BGA

Blood gas analyzer

TEa

Total allowable error

Footnotes

a.

Plasma tube, Becton, Dickinson and Company, Franklin Lakes, NJ.

b.

Stat Profile pHOx Ultra, Nova Biomedical, Waltham, Mass.

c.

Stat Profile Prime Plus Vet, Nova Biomedical, Waltham, Mass.

d.

Vitros 4600, Ortho Clinical Diagnostics, Raritan, NJ.

e.

MedCalc statistical software, version 18.11.6, MedCalc Software Ltd, Ostend, Belgium.

References

  • 1.

    O'Brien MA. Diabetic emergencies in small animals. Vet Clin North Am Small Anim Pract 2010;40:317333.

  • 2.

    Schaer M. Therapeutic approach to electrolyte emergencies. Vet Clin North Am Small Anim Pract 2008;38:513533.

  • 3.

    Gonzalez AL, Waddell LS. Blood gas analyzers. Top Companion Anim Med 2016;31:2734.

  • 4.

    Flatland B, Freeman KP, Vap LM, et al. ASVCP guidelines: quality assurance for point-of-care testing in veterinary medicine. Vet Clin Pathol 2013;42:405423.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 5.

    Stat Profile Prime Plus VET Critical Care Analyzer. Available at: www.novabio.us/prime-plus-vet/index.php. Accessed Jun 27, 2019.

  • 6.

    Flatland B, Freeman KP, Friedrichs KR, et al. ASVCP quality assurance guidelines: control of general analytical factors in veterinary laboratories. Vet Clin Pathol 2010;39:264277.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7.

    Tate JR, Sikaris KA, Jones GRD, et al. Harmonising adult and paediatric reference intervals in Australia and New Zealand: an evidence-based approach for establishing a first panel of chemistry analytes. Clin Biochem Rev 2014;35:213235.

    • Search Google Scholar
    • Export Citation
  • 8.

    Langston C. Managing fluid and electrolyte disorders in kidney disease. Vet Clin North Am Small Anim Pract 2017;47:471490.

  • 9.

    Tate JR, Yen T, Jones GRD. Transference and validation of reference intervals. Clin Chem 2015;61:10121015.

  • 10.

    Friedrichs KR, Harr KE, Freeman KP, et al. ASVCP reference interval guidelines: determination of de novo reference intervals in veterinary species and other related topics. Vet Clin Pathol 2012;41:441453.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11.

    Bell R, Harr K, Rishniw M, et al. Survey of point-of-care instrumentation, analysis, and quality assurance in veterinary practice. Vet Clin Pathol 2014;43:185192.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 12.

    Harr KE, Flatland B, Nabity M, et al. ASVCP guidelines: allowable total error guidelines for biochemistry. Vet Clin Pathol 2013;42:424436.

  • 13.

    Budak YU, Huysal K, Polat M. Use of a blood gas analyzer and a laboratory autoanalyzer in routine practice to measure electrolytes in intensive care unit patients. BMC Anesthesiol 2012;12:17.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14.

    Jain A, Subhan I, Joshi M. Comparison of the point-of-care blood gas analyzer versus the laboratory auto-analyzer for the measurement of electrolytes. Int J Emerg Med 2009;2:117120.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15.

    Uyanik M, Sertoglu E, Kayadibi H, et al. Comparison of blood gas, electrolyte and metabolite results measured with two different blood gas analyzers and a core laboratory analyzer. Scand J Clin Lab Invest 2015;75:97105.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16.

    Dimeski G, Morgan TJ, Presneill JJ, et al. Disagreement between ion selective electrode direct and indirect sodium measurements: estimation of the problem in a tertiary referral hospital. J Crit Care 2012;27:326.e9326.e16.

    • Search Google Scholar
    • Export Citation
  • 17.

    Thoresen SI, Havre GN, Morberg H, et al. Effects of storage time on chemistry results from canine whole blood, heparinized whole blood, serum and heparinized plasma. Vet Clin Pathol 1992;21:8894.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18.

    Flatland B, Camus MS, Baral RM. Analytical quality goals—a review. Vet Clin Pathol 2018;47:527538.

Supplementary Materials

Contributor Notes

Address correspondence to Dr. Schmitz (kschmitz2012@gmail.com).