원저 Lab Med Online Vol. 5, No. 2: 57-62, April 2015 임상화학 현장검사화학분석기기인 Abbott i-stat CHEM8+ 의성능평가 Evaluation of i-stat CHEM8+ Point-of-Care Chemistry Analyzer 김도균 신화춘 김병광 정순호 임종백 Do-kyun Kim, M.D., Hwachoon Shin, M.T., Byungkwang Kim, M.T., Soon-Ho Jeong, M.T., Jong-Baeck Lim, M.D. 연세대학교의과대학부속강남세브란스병원진단검사의학과 Department of Laboratory Medicine, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea 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. Key Words: Clinical chemistry tests, Evaluation studies, Point of care systems, Verification 서론 현장검사 (point of care testing, POCT) 란진료현장에서시행되 는신속검사로, 병실, 응급실, 중환자실, 신생아중환자실등에서 시행되는혈당검사, 동맥혈가스검사, 빌리루빈검사등이이에포 함된다. 현장검사는대형장비를이용한검사보다신속하게결과를 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, E-mail: jlim@yuhs.ac Received: June 21, 2014 Revision received: October 10, 2014 Accepted: October 13, 2014 This article is available from http://www.labmedonline.org 2015, Laboratory Medicine Online 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. 얻을수있으며, 이를통해빠르게질병의진단및처치가가능하다 [1, 2]. 현장검사는그적용범위가점점증가하여 2007년에는전세계적으로매출이 70억불이상되었으며, 최근에도그비율이점점증가하여, 매년 9% 정도의성장률을보이고있다 [3]. Abbott i-stat CHEM8+ (Abbott, Abbott Park, IL, USA) 로측정되는나트륨 (sodium, Na + ), 칼륨 (potassium, K + ), 염소 (chloride, Cl ), 총이산화탄소 (total CO 2, tco 2), 혈액요소질소 (blood urea nitrogen, BUN), 크레아티닌 (creatinine), 혈당 (glucose), 이온화칼슘 (ionized calcium, ica) 은환자가병원에내원하였을때기본적으로시행되는임상화학검사들이며, 이러한항목들은환자의전해질상태, 산-염기평형상태등의초기환자상태를평가하기위해꼭시행되어야되는항목들이다. 따라서, 이러한기본임상화학검사를시행하는현장검사기기가임상현장에서사용되기위해서는그측정성능의평가및기존대형장비와의비교평가가필수적이다 [4]. 하지만, 현재까지국내외에서 Abbott i-stat CHEM8+ 의기본적인성능평가에대한학술적보고는매우드물다. 그러므로, 본연구에서는 Abbott i-stat CHEM8+ 가측정하는 8가지항목인 eissn 2093-6338 www.labmedonline.org 57
Na +, K +, Cl, tco 2, BUN, Creatinine, Glucose, ica에대하여 Clinical and Laboratory Standards Institute (CLSI) 의기준에따라정밀도, 직선성, 상관성등의성능평가를시행하였다. 재료및방법 후, 원심분리후본원의기준장비 Hitachi Clinical analyzer 7600 (Hitachi, Tokyo, Japan) 으로 ica를제외한 7가지항목에대해검사를시행하였다. 수집된검체중 57개의검체는전혈검체의상태로 i-stat CHEM8+ 와 NOVA Critical Care Xpress (CCX) (Nova Biomedical corporation, Miami, USA) 로 ica을측정하여비교하였다. 1. 장비와검체 Abbott i-stat Clinical Chemistry Analyzer (Abbott, Abbott Park, IL, USA) 는전혈검체를카트리지에넣은후기계에삽입하면 2분이내에검사결과를얻을수있으며, 카트리지의종류에따라서전해질, 동맥혈가스, 심근표지자, 기본적인화학검사등의 1-13개항목들을전위차분석법 (Potentiometry) 으로측정하는장비이다. 본연구에서사용한카트리지는 i-stat CHEM8+ 로 Na +, K +, Cl, tco 2, BUN, Creatinine, Glucose, ica의 8가지항목을측정한다. 본장비의크기는 7.69 23.48 7.24 cm이며, 무게도 635 g으로손쉽게이동가능하다. 각항목들의측정가능범위는 Na + 는 100-180 mmol/l, K + 는 2.0-9.0 mmol/l, Cl 는 65-140 mmol/l, tco 2 는 5-50 mmol/l, BUN 은 3-140 mg/dl, Creatinine은 0.2-20 mg/dl, glucose는 20-700 mg/dl, ica은 0.25-2.50 mmol/l로임상적으로필요한범위를충분히포함하고있다. 2. 정밀도 (Precision) 평가정밀도평가는 CLSI EP15-A [5] 에따라제조사에서제공하는고농도및저농도의 2가지정도관리물질 i-stat CHEM8+ Calibration Verification Set Level 2, Level 4 (Abbott Point of care Inc., Abbott Park, IL, USA) 를이용하여총 5일간하루에 2회, 매검사마다 2회씩반복측정하여시행하였으며, 하루에시행되는 2회의검사는최소한 2시간이상의간격을두고측정하였다. 3. 직선성 (Linearity) 평가직선성평가는 CLSI EP6-A[6] 에준하여제조사에서제공하는고농도에서저농도를포함하는 5가지의정도관리물질 i-stat CHEM8+ Calibration Verification Set Level 1, Level 2, Level 3, Level 4, Level 5 (Abbott Point of care Inc., Abbott Park, IL, USA) 를이용하여시행하였다. 4. 상관성 (Method comparison) 평가상관성평가는 CLSI EP9-A2 [7] 에준하여 40개이상의검체를대상으로시행하였다. 2013년 12월부터 2014년 4월까지리튬헤파린관에수집된환자검체 113개를대상으로하였으며, 검체를수집한즉시전혈검체의상태로 i-stat CHEM8+ 를이용하여측정한 5. 통계분석통계분석은 Microsoft Excel (Microsoft Corporation, WA, USA) 과 Analyse-it (Analyse-it Software Ltd., Leeds, UK) 을사용하여시행하였다. 정밀도평가는표준편차 (standard deviation, SD) 와변이계수 (coefficient variant, CV) 를이용하였다. 검사차례내정밀도와총정밀도는제조사에서제시한표준편차 (claimed SD) 와측정된표준편차를비교하여평가하였으며, 변이계수도함께평가하였다. 직선성은선형회귀분석을통하여회귀방정식과결정계수, 그리고비직선성 % 를구하여평가하였다. 상관성은상관계수를평가하였으며, Deming 회귀분석을시행하여기울기와 y절편을구한후, 각항목에대한 Statland [8] 가제시하는두가지또는세가지농도의임상적중요농도 (medical decision level) 를설정하여, 각항목의상관성방정식을통해임상적중요농도에서 i-stat CHEM8+ 의측정예측치를구한후, 그측정예측치가 CLIA88에서제시한허용오차범위 (acceptable performance) 의기준내에포함되는지를평가하였다. 결과 1. 정밀도평가저농도와고농도의 2가지표준물질을이용하여측정한 Na +, K +, Cl -, tco 2, BUN, Creatinine, Glucose, ica의검사차례내정밀도및총정밀도의표준편차와변이계수를 Table 1에정리하였다. 검사차례내정밀도의표준편차는저농도와고농도에서각각 Na + 는 0.34 mmol/l, 0.50 mmol/l, K + 는 0.00 mmol/l, 0.02 mmol/l, Cl 는 0.74 mmol/l, 0.79 mmol/l, tco 2 는 0.00 mg/dl, 0.52 mg/dl, BUN 은 0.00 mg/dl, 0.76 mg/dl, Creatinine은 0.05 mg/dl, 0.09 mg/dl, Glucose는 0.41 mg/dl, 0.89 mg/dl, ica은 0.00 mmol/l, 0.01 mmol/l였다. 총정밀도의표준편차는저농도와고농도에서각각 Na + 의경우 0.54 mmol/l, 0.49 mmol/l, K + 의경우 0.00 mmol/l, 0.02 mmol/l, Cl 의경우 0.97 mmol/l, 0.79 mmol/l, tco 2 의경우 0.00 mg/dl, 0.46 mg/dl, BUN의경우 0.00 mg/dl, 0.87 mg/dl, Creatinine의경우 0.05 mg/dl, 0.12 mg/dl, Glucose 의경우 0.52 mg/dl, 1.34 mg/dl, ica의경우 0.00 mmol/l, 0.01 mmol/l였다. 검사차례내정밀도의표준편차는 Cl - 의고농도의경우와 Creatinine 의저농도의경우를제외한모든항목에서제조사에서제시한표 58 www.labmedonline.org
준편차보다낮았다. 총정밀도의표준편차는 Na + 의저농도의경우와 Cl - 의저농도와고농도의경우, Creatinine의저농도의경우, 그리고 BUN의고농도의경우에서제조사에서제시한표준편차보다높은값을보였으나, 검증값 (verification value) 을구하여비교하였을때, Cl - 의저농도와고농도의경우를제외한모든항목에서검증값보다낮아우수한정밀도를보였다. 총정밀도의변이계수는저농도와고농도에서각각 Na + 는 0.45%, 0.30%, K + 는 0.00%, 0.35%, Cl - 는 1.28%, 0.72%, tco 2 는 0.00%, 1.37%, Creatinine은 7.77%, 2.91%, BUN은 1.36%, 0.00%, ica는 0.98%, 0.64%, Glucose 는 1.25%, 0.46% 로, Creatinine의저농도와고농도의경우를제외한모든항목에서 2% 이내로우수한결과를보였다 [1]. 2. 직선성 5가지농도의정도관리물질을이용하여시행한직선성평가에서 Na +, K +, Cl, tco 2, BUN, Creatinine, Glucose, ica의결정계수 (R 2 ) 는각각 0.99986, 0.99988, 0.99952, 0.99253, 0.99997, 0.99253, 0.99995, 0.99991로모두 0.99 이상으로우수한결과를보였으며 (Table 2), 각항목들의측정치를가장잘반영하는방정식은 Na +, Cl, tco 2, BUN, Creatinine, Glucose, ica 항목에서 1차함수로좋은직선성을보였으며, Glucose 는 2차함수, K +, tco 2 는 3차함수가적합한것으로계산되었다. Glucose의 5가지농도 (27.2 mg/dl, 40.9 mg/dl, 124.1 mg/dl, 286.6 mg/dl, 618.1 mg/dl) 에서의비직선성 % (Nonlinearity%) 는각각 -4.9%, -2.3%, 0.7%, 0.9%, -0.2% 로모두 10% 미만으로 1차함수와통계적으로유의미한차이를보이지않았다. K + 의 5가지농도 (2.08 mmol/l, 2.84 mmol/l, 3.75 mmol/l, 6.42 mmol/l, 7.86 mmol/l) 에서의비직선성 % 는각각 1.4%, -0.6%, -0.8%, 0.4%, -0.1% 이고, tco 2 는 5가지농도 (13.3 mg/ dl, 19.2 mg/dl, 22.6 mg/dl, 32.4 mg/dl, 46.0 mg/dl) 에서의비직선성 % 는각각 -4.8%, -1.6%, 1.0%, 5.4%, -2.2% 로, 모두 10% 미만으로우수하였다 (Table 3). 직선성을평가하는데사용한 5가지농도의정도관리물질이포함하는범위는측정가능범위를모두포함하 Table 1. Precision of i-stat CHEM8+ 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) - - Table 2. Linearity of i-stat CHEM8+ Analytes Unit Range Slope Intercept R 2 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 www.labmedonline.org 59
Table 3. 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=-0.004x 3 +0.062x 2 2.1 1.4% Creatinine mg/dl y=1.018x-0.0586 0.36 - +0.6985x+0.411 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=-0.001x 2 +1.025x 27.2-4.9% 75.5 - -0.3584 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=0.001x 3 +0.042x 2 13.3-4.8% ica mmol/l y=0.999x+0.0060 0.253 - +0.115x+5.316 19.2-1.6% 0.773-22.6 1.0% 1.264-46.0-2.2% 1.475-32.4 5.4% 2.209 - Table 4. Range of value and correlation coefficient of comparison between i-stat CHEM8+ and main chemistry analyzer Range of value Analyte n Comparison method Comparison i-stat r 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 지는못하였지만, 임상검체에서일반적으로측정되는값들을충분히포함하는범위였다. 3. 상관성평가임상검체 113개를이용하여 i-stat CHEM8+ 와검사실표준장비 (Hitachi Clinical Analyzer 7600와 NOVA CCX) 의상관성평가를실시하였다. 각기기들의결과값들의상관계수 (r) 를구하였고 (Table 4), Deming 회귀분석을통하여두기기간의결과값의상관성방정식을구하였다 (Table 5). 상관계수는 K + 와 BUN, Glucose에서각각 0.964, 0.991, 0.981로 0.95 이상이었으며 [1], Na +, Cl, tco 2, Creatinine, Glucose에서는각각 0.845, 0.855, 0.710, 0.889, 0.906으로 0.95보다낮았다. 또한, CLIA에서제시하는허용오차범위를만족시키지못하는검체의비율은 Na +, K +, Cl, tco 2, BUN, Creatinine, Glucose, ica에서각각 0.00%, 0.88%, 0.00%, 19.47%, 8.85%, 5.31%, 6.19%, 21.05% 였다 [9]. 그리고, Deming 회귀분석을통해구한상관성방정식을이용하여임상적중요농도에서예측되는값은, Na + 의경우 135 mmol/l, 150 mmol/l에서각각 135.99 mmol/ L, 148.37 mmol/l였으며, K + 는 3 mmol/l, 6 mmol/l에서각각 2.87 mmol/l, 6.16 mmol/l, Cl 는 90 mmol/l, 112 mmol/l에서각각 86.67 mmol/l, 113.35 mmol/l, tco 2 는 20 mmol/l, 33 mg/dl에서각각 21.55 mg/dl, 34.54 mg/dl, BUN은 6 mg/dl, 27 mg/dl, 에서각각 4.37 mg/dl, 29.46 mg/dl, Creatinine은 0.8 mg/dl, 1.6 mg/ dl, 6.0 mg/dl에서각각 0.92 mg/dl, 1.69 mg/dl, 5.95 mg/dl, Glucose는 45 mg/dl, 120 mg/dl, 180 mg/dl에서각각 46.55 mg/dl, 119.15 mg/dl, 177.23 mg/dl, ica은 1.10 mmol/l, 1.30 mmol/l에서 1.15 mmol/l, 1.32 mmol/l였다. 60 www.labmedonline.org
Table 5. 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 고찰 현장검사는기존의대형장비검사에비해정확도는낮지만, 신속하게검사결과를보고할수있으므로, 보다빠른임상적판단및처치를가능하게한다. 본연구에서평가한 i-stat CHEM8+ 는전혈검체를이용하여기본적인 8가지임상화학검사종목에대하여 2분안에결과보고가가능한장비로써신속한산-염기평형과전해질균형, glucose, creatinine 결과가필요한응급실, 수술실, 혈액투석실등에서유용하게사용될수있다 [10, 11]. 95 μl의적은검체만으로결과를얻을수있기때문에, 많은양의검체를채혈하기힘든신생아를대상으로한검사에도사용될수있다 [12]. 그리고, 대형검사장비가갖추어져있지않은야외진료실이나 1차또는 2차병원에서신속하게환자의응급한정도를판단할수있게해줄수있을것으로생각된다 [13]. 저농도와고농도의두가지정도관리물질을이용한 i-stat CHEM8+ 의정밀도평가에서, 총정밀도의표준편차 (SD) 와변이계수 (CV) 는 Cl 와 Creatinine을제외한 6가지임상화학검사에서우수한정밀도를보였다. Cl 의총정밀도표준편차는저농도와고농도각각에서 0.97 mmol/l, 0.79 mmol/l로제조사에서제시한표준편차인 0.54 mmol/l, 0.56 mmol/l보다높았으며검증값인 0.76, 0.74 mmol/l보다높아기준을충족하지못하였다. 하지만, Cl 의변이계수는저농도와고농도에서각각 1.28%, 0.72% 로, 대형장비를평가하는기준이되는 Ricos 등 [14] 이제시하는 Cl - 의 Imprecision (%) 인 0.6% 와비교하였을때, 현장검사장비의한계를고려한다면비교적좋은정밀도를보였다. i-stat CHEM8+ 의직선성평가에서 8가지항목모두에서결정계수가 0.99 이상으로우수한결과를보였으며, Analyse-it을통해얻어진함수역시 Na +, Cl, tco 2, BUN, Creatinine, Glucose, ica에서 1차함수로우수한직선성으로보였으며, Glucose는 2차함수, K + 와 tco 2 는 3차함수가적합한것으로계산되었지만이항목들에서도비직선성 % 가모두 10% 미만으로 1차함수와통계적으로유의한차이를보이지않아임상적으로적용가능한직선성을보였다. 본원에서사용한대형검사장비 (Hitachi Clinical Analyzer 7600 와 NOVA CCX) 와의상관성평가에서는 K +, BUN, Glucose의경우상관계수 0.95 이상으로우수한상관성을보였다. 상관계수 0.95 이하인 5가지항목중 Na +, Cl, Creatinine의경우 CLIA88에서제시하는허용오차범위를넘어서는검체는각각 0.00%, 0.00%, 5.31% 이며, Statland [8] 와 CLIA88에서제시하는임상적중요농도와허용오차범위를이용하였을때우수한상관성을보였다. 하지만, tco 2 와 ica의경우검사실장비와비교하였을때, CLIA88의허용오차범위를넘어서는검체는각각 19.47%, 21.05% 로임상에서사용할경우주의를기울여야할것이다. 결론적으로 i-stat CHEM8+ 는정밀도와직선성평가에서우수한성적을보였으며, 기존검사실의대형장비와의비교평가에서도비교적우수한상관성을보여실제임상현장에서사용하기에적합한현장검사화학분석기라판단된다. 또한 95 μl의적은양으로 www.labmedonline.org 61
도 2분이내에결과보고가가능하므로특히응급실, 중환자실등신속한결과가필요한임상현장과신생아중환자실과같이많은양의채혈이어려운곳에서그유용성이클것으로판단된다. 요약 배경 : 본연구에서는임상화학검사현장검사기기인 Abbot사의 i-stat CHEM8+ 를이용하여 Na +, K +, Cl, tco 2, BUN, Creatinine, Glucose, ica를포함하는 8가지기본화학검사항목에대한측정능력을평가하였다. 방법 : 상기 8가지항목에대하여 CLSI의기준을이용하여정밀도, 직선성을평가하였고, 대형검사기기 (Hitachi Clinical Analyzer 7600과 NOVA CCX) 와 i-stat CHEM8+ 간의기기간상관성평가를실시하였다. 통계분석은 Microsoft excel과 Analyse-it을통하여시행하였다. 결과 : 검사차례내정밀도와총정밀도의표준편차는 Cl 를제외한 7가지항목에서제조사에서제시한표준편차또는 verification value 내로우수한결과를보였다. 총정밀도는변이계수가 creatinine을제외한 7가지항목에서 2% 내로우수한결과를보였다. 직선성평가에서모든 8가지항목에서 1차함수또는적어도 1차함수와통계적으로유의한차이를보이지않는결과를보여우수한직선성을보였다. 기존대형장비와의상관성에서도모든항목에서상관계수가 0.95 이상이거나, 임상적중요농도에서의예측치가허용오차범위내로우수한결과를보여주었다. 결론 : Abbott i-stat CHEM8+ 는 8가지항목을측정하는장비이며, 정밀도, 직선성, 상관성을포함하는측정능력은임상적으로사용하기에충분한결과를보였다. 본장비는현장에서전혈검체를바로이용하여 2분이내에비교적정확한결과를알수있기때문에응급실이나중환자실과같은즉각적인검사결과가필요한부서에서유용성이있을것으로생각된다. REFERENCES 1. Park H, Ko DH, Kim JQ, Song SH. Performance evaluation of the Piccolo xpress Point-of-care Chemistry Analyzer. Korean J Lab Med 2009;29:430-8. 2. St John A. The Evidence to Support Point-of-Care Testing. Clin Biochem Rev 2010;31:111-9. 3. Nichols JH. Point of care testing. Clin Lab Med 2007;27:893-908. 4. Matteucci E, Della Bartola L, Rossi L, Pellegrini G, Giampietro O. Improving CardioCheck PA analytical performance: three-year study. Clin Chem Lab Med 2014 ;52:1291-6. 5. Clinical and Laboratory Standards Institute. User Demonstration of Performance for Precision and Accuracy; Approved Guideline. Document EP15-A. Wayne, PA: Clinical and Laboratory Standards Institute, 2001:67. 6. Clinical and Laboratory Standards Institute. Evaluation of the linearity of quantitative measurement procedure: a statistical approach; Approved guideline. Document EP6-A. Wayne, PA: Clinical and Laboratory Standards Institute, 2003:23. 7 Clinical and Laboratory Standards Institute. Method comparison and bias estimation using patient samples; Approved guideline-2nd edition. Document EP9-A2. Wayne, PA: Clinical and Laboratory Standard Institute, 2002:22. 8. Statland BE. Clinical Decision Levels for Laboratory Tests, Second Edition, Oradell, NJ, 1987. 9. Centers for Disease Control and prevention, Clinical Laboratory Improvement Amendments Regulation, Standards and Certification: Laboratory Requirements (42 CFR 493) http://wwwn.cdc.gov/clia/regulatory/default.aspx (uptated on OCT 2003). 10. Rhee AJ and Khan RA. Laboratory point-of-care monitoring in the operating room. Curr Opin Anaesthesiol 2010;23:741-8. 11. Gault MH and Harding CE. Evaluation of i-stat portable clinical analyzer in a hemodialysis unit. Clin Biochem 1996;29:117-24. 12. Tendl KA, Christoph J, Bohn A, Herkner KR, Pollak A, Prusa AR. Two site evaluation of the performance of a new generation point-of-care glucose meter for use in a neonatal intensive care unit. Clin Chem Lab Med 2013;51:1747-54. 13. Tortella BJ, Lavery RF, Lavery RF, Siegel JH. Precision, accuracy, and managed care implications of a hand-held whole blood analyzer in the prehospital setting. Am J Clin Pathol 1996;106:124-7. 14 Ricós C, Alvarez V, Cava F, García-Lario JV, Hernández A, Jiménez CV, et al. Current databases on biological variation: pros, cons and progress. Scand J Clin Lab Invest 1999;59:491-500. 62 www.labmedonline.org