Korean J Lab Med.  2006 Dec;26(6):400-407. 10.3343/kjlm.2006.26.6.400.

Evaluation of Fixed Quality Control Range of Bayer Rapidpoint 400 Blood Gas and Electrolyte Analyzer with Six Sigma Metrics

• Kim Y
• Min WK
• Park H

• KMID: 1889817
• DOI: http://doi.org/10.3343/kjlm.2006.26.6.400

Abstract

BACKGROUND: Bayer Rapidpoint 400 analyzer for point of care testing (POCT) uses fixed quality control (QC) range even when the lot number of a cartridge for quality control changes. To evaluate the fixed QC range recommended by the manufacturer, we analyzed internal QC data of 9 analyzers with Six Sigma metrics.
MATERIALS AND METHODS
We investigated QC data of 9 analyzers over 5 months from May to September, 2004 for 8 parameters (pH, pCO2, pO2, Na+, K+, iCa++, Cl-, and glucose). One hundred eighty six groups of QC data were analyzed with capability index (C(p)=total allowable error (TEa)/3 standard deviation (SD)) and capability index considering bias (C(pk),=(TEa-bias)/3 SD). Acceptability was evaluated with criteria of 1.33 C(pk), 4 sigma level or quality criteria of the Clinical Laboratory Improvement Amendments of 1988 (CLIA'88).
RESULTS
In 80.7% (150 of 186 groups), both C(p) and C(pk) were at or above 1.33, which indicated that the use of fixed QC range was adequate. In 19.3% (36 of 186 groups), C(pk) was below 1.33, which indicated the inadequacy of fixed QC range. Among them 14.5% (27 of 186 groups) showed C(p) below 1.33, indicating that the errors had a random factor and 4.8% (9 of 186 groups) had C(p) at or above 1.33, indicating that the errors had a systematic factor.
CONCLUSIONS
The quality criteria mandated by CLIA '88 was satisfied in about 80% of study groups using fixed QC ranges, but in about 20%, more strict instrument maintenance and specimen handling by operators, and quality improvement of QC materials by manufacturer was required.

Keyword

Blood gas and electrolyte analyzer; Capability index; Capability index considering bias; Point of care testing; Quality control; Six Sigma

MeSH Terms

Bias (Epidemiology)
Quality Control*
Quality Improvement
Specimen Handling

Reference

References

1. Handorf CR. Background-setting the stage for alternate-site laboratory testing. Clin Lab Med. 1994; 14:451–8.

2. Sands VM, Auerbach PS, Birnbaum J, Green M. Evaluation of a portable clinical blood analyzer in the emergency department. Acad Emerg Med. 1995; 2:172–8.

3. Aduen J, Bernstein WK, Khastgir T, Miller J, Kerzner R, Bhatiani A, et al. The use and clinical importance of a substrate-specific electrode for rapid determination of blood lactate concentrations. JAMA. 1994; 272:1678–85.

4. Salem M, Chernow B, Burke R, Stacey JA, Slogoff M, Sood S. Bedside diagnostic testing: its accuracy, rapidity, and utility in blood conservation. JAMA. 1991; 266:382–9.

5. Laessig RH, Ehrmeyer SS. Automatic quality control: the rapid-point 400 approach to QA/AQC. Bayer Diagnostics.

6. Westgard JO, Klee GG. Quality management. Burtis CA, Ashwood ER, Bruns DE, editors. Tietz textbook of clinical chemistry and molecular diagnostics. 4th ed.Philadelphia: Elsevier Saunders;2006. p. 488–9.

7. Burnett L, Hegedus G, Chesher D, Burnett J, Costagnanna G. Application of process capability indices to quality control in a clinical chemistry laboratory. Clin Chem. 1996; 42:2035–7.

8. Westgard JO, Seehafer JJ, Barry PL. European specifications for imprecision and inaccuracy compared with operating specifications that assure the quality required by US CLIA proficiency-testing criteria. Clin Chem. 1994; 40:1228–32.