Lab Med Online LMO Laboratory Medicine Online 2093-6338 The Korean Society for Laboratory Medicine 10.3343/lmo.2015.5.2.57 Original Article Clinical Chemistry Evaluation of i-STAT CHEM8+ Point-of-Care Chemistry Analyzer Kim Do-kyun M.D. Shin Hwachoon M.T. Kim Byungkwang M.T. Jeong Soon-Ho M.T. Lim Jong-Baeck M.D. Department of Laboratory Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea. Corresponding author: Jong-Baeck Lim. Department of Laboratory Medicine, Yonsei University College of Medicine, Gangnam Severance Hospital, 211 Unju-ro, Gangnam-gu, Seoul 135-752, Korea. Tel: +82-2-2019-3533, Fax: +82-2-2057-8926, jlim@yuhs.ac 04 2015 01 04 2015 5 2 57 62 21 06 2014 10 10 2014 13 10 2014 © 2015, Laboratory Medicine Online 2015 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Background

We evaluated the analytical performance of the Abbott i-STAT CHEM8+, a point-of-care testing system that measures 8 basic chemical analytes, namely, sodium, potassium, chloride, total carbon dioxide, BUN, creatinine, glucose, and ionized calcium.

 Methods

The precision and linearity of 8 analytes were evaluated according to the CLSI guidelines EP15-A and EP6-A, respectively, using standard material provided by the manufacturer. i-STAT CHEM8+ and other primary methods (e.g. Hitachi Clinical Analyzer 7600 for 7 analytes, Nova CCX for ionized calcium) were also compared according to the CLSI guideline EP9-A2, using 113 patient samples.

 Results

The standard deviation (SD) of within-run and total precision of 7 analytes except chloride was within the claimed SD or within the verification value. The coefficient of variation of total precision of 7 analytes except creatinine was within 2%. With regard to linearity, all 8 analytes showed first-order equation or at least no statistical difference with the first-order equation. We observed that the efficiency of i-STAT CHEM8+ was comparable to that of primary methods, and that this method has potential applications in the clinical laboratory.

 Conclusions

i-STAT CHEM8+ showed good precision and linearity, and an efficiency comparable to that shown by routine chemistry analyzers; thus, it has potential applications in the clinical laboratory. It can provide much faster results and relatively accurate value to clinicians in need of immediate results, such as in an emergency unit or in the intensive care unit.

 Clinical chemistry tests Evaluation studies Point of care systems Verification

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Analyte Unit Sample Claimed value Evaluated value Verification value
Mean Within SD Total SD Mean Within SD (CV%) Total SD (CV%) Within SD Total SD
Na+ mmol/L Low 119.40 0.46 0.46 119.45 0.34 (0.29) 0.54 (0.45) 0.62 0.94
High 160.80 0.53 0.53 161.15 0.50 (0.31) 0.49 (0.30) - -
K+ mmol/L Low 2.85 0.04 0.04 2.80 0.00 (0.00) 0.00 (0.00) - -
High 6.30 0.04 0.04 6.40 0.02 (0.35) 0.02 (0.35) - -
Cl- mmol/L Low 75.50 0.54 0.54 75.35 0.74 (0.98) 0.97 (1.28) 0.75 0.76
High 109.50 0.56 0.56 109.75 0.79 (0.72) 0.79 (0.72) 0.78 0.74
tCO2 mg/dL Low 19.20 0.62 0.62 19.00 0.00 (0.00) 0.00 (0.00) - -
High 32.40 0.62 0.62 33.70 0.52 (1.53) 0.46 (1.37) - -
Creatinine mg/dL Low 0.64 0.04 0.04 0.64 0.05 (7.33) 0.05 (7.77) 0.05 0.05
High 4.07 0.13 0.13 4.04 0.09 (2.35) 0.12 (2.91) - -
BUN mg/dL Low 4.90 0.45 0.45 5.00 0.00 (1.20) 0.00 (1.36) - -
High 62.40 0.76 0.76 63.75 0.76 (0.00) 0.87 (0.00) 1.03 1.02
iCa mmol/L Low 0.77 0.01 0.01 0.78 0.00 (0.77) 0.00 (0.98) - -
High 1.48 0.02 0.02 1.50 0.01 (0.41) 0.01 (0.64) - -
Glucose mg/dL Low 40.90 0.68 0.68 41.60 0.41 (0.98) 0.52 (1.25) - -
High 286.60 2.40 2.40 290.50 0.89 (0.31) 1.34 (0.46) - -
Linearity of i-STAT CHEM8+
Analytes Unit Range Slope Intercept R2
Na+ mmol/L 98.4-180.0 1.0170 -2.4485 0.99986
K+ mmol/L 2.08-7.86 0.9929 0.0026 0.99988
Cl- mmol/L 70.3-123.2 0.9880 1.4451 0.99952
tCO2 mg/dL 13.3-46.0 0.9757 0.6476 0.99253
BUN mg/dL 2.1-123.9 1.0009 0.1850 0.99997
Creatinine mg/dL 0.36-14.36 1.0175 -0.0586 0.99253
Glucose mg/dL 27.2-618.1 0.9943 1.7806 0.99995
iCa mmol/L 0.25-2.21 0.9993 0.0060 0.99991
Best-fit equation and non-linearity% of i-STAT CHEM8+
Analytes Unit Best-fit equation Assigned value Nonlinearity% Analytes Unit Best-fit equation Assigned value Nonlinearity%
Na+ mmol/L y = 1.017x-2.448 98.4 - BUN mg/dL y = 1.001x+0.185 2.1 -
119.4 - 4.9 -
133.4 - 10.6 -
160.8 - 62.4 -
180.0 - 123.9 -
K+ mmol/L y = -0.004x3+0.062x2+0.6985x+0.411 2.1 1.4% Creatinine mg/dL y = 1.018x-0.0586 0.36 -
2.8 -0.6% 0.64 -
3.8 -0.8% 1.84 -
6.4 0.4% 4.07 -
7.9 -0.1% 14.36 -
Cl- mmol/L y = 0.988x+1.445 70.3 - Glucose mg/dL y = -0.001x2+1.025x-0.3584 27.2 -4.9%
75.5 - 40.9 -2.3%
89.9 - 124.1 0.7%
109.5 - 286.6 0.9%
123.2 - 618.1 -0.2%
tCO2 mg/dL y = 0.001x3+0.042x2+0.115x+5.316 13.3 -4.8% iCa mmol/L y = 0.999x+0.0060 0.253 -
19.2 -1.6% 0.773 -
22.6 1.0% 1.264 -
46.0 -2.2% 1.475 -
32.4 5.4% 2.209 -
Range of value and correlation coefficient of comparison between i-STAT CHEM8+ and main chemistry analyzer
Analyte n Comparison method Range of value r
Comparison i-STAT
Na+ 113 Hitachi 7600 125-146 126-146 0.845
K+ 113 Hitachi 7600 2.50-4.65 2.40-4.80 0.964
Cl- 113 Hitachi 7600 95.0-109.7 92.0-109.0 0.855
tCO2 113 Hitachi 7600 19.2-33.2 22.0-36.0 0.710
BUN 113 Hitachi 7600 3.6-25.0 3.0-26.0 0.991
Creatinine 113 Hitachi 7600 0.26-1.36 0.30-1.70 0.889
Glucose 113 Hitachi 7600 125.0-217.0 23.0-214.0 0.981
iCa 57 Nova CCX 0.63-1.37 0.79-1.41 0.906
Comparison of i-STAT CHEM8+ with routine chemistry analyzer at the medical decision level by Deming regression
Analytes Slope (95% CI) Intercept (95% CI) Decision level Acceptable performance Low limit High limit Expected value Percent of samples not satisfying CLIA requirement
Na+ 0.825 (0.687-0.962) 24.630 (5.050-44.200) 135 ± 4 mmol/L 131 139 135.99 0.00%
150 ± 4 mmol/L 146 154 148.37
K+ 1.098 (1.038-1.158) -0.429 (-0.657--0.201) 3 ± 0.5 mmol/L 2.5 3.5 2.87 0.88%
6 ± 0.5 mmol/L 5.5 6.5 6.16
Cl- 1.213 (1.084-1.341) -22.470 (-35.690--9.249) 90 ± 5 mmol/L 85 95 86.67 0.00%
112 ± 5 mmol/L 107 117 113.35
tCO2 1.299 (1.072-1.526) -4.424 (-10.210-1.364) 20 ± 5 mg/dL 15 25 21.55 19.47%
33 ± 5 mg/dL 28 38 34.54
BUN 1.195 (1.151-1.239) 2.802 (-3.280--2.324) 6 ± 2 mg/dL 4 8 4.37 8.85%
27 ± 2 mg/dL 25 29 29.46
Creatinine 0.968 (0.849-1.087) 0.145 (0.061-0.229) 0.8 ± 0.3 mg/dL 0.2 1.1 0.92 5.31%
1.6 ± 0.3 mg/dL 1.3 1.9 1.69
6.0 ± 0.3 mg/dL 5.7 6.3 5.95
Glucose 0.974 (0.937-1.011) 2.989 (-0.653-6.631) 45 ± 6 mg/dL 44 56 46.55 6.19%
120 ± 6 mg/dL 108 132 119.15
180 ± 6 mg/dL 162 198 177.23
iCa 0.834 (0.694-0.973) 0.234 (0.066-0.401) 1.1 ± 5% 1.05 1.16 1.15 21.05%
1.3 ± 5% 1.24 1.37 1.32