대한진단검사의학회지제 29 권제 5 호 29 Korean J Lab Med 29;29:43-8 DOI.3343/kjlm.29.29.5.43 Original Article Clinical Chemistry 현장검사화학분석장비 Piccolo xpress Chemistry Analyzer 성능평가 박현웅,2 고대현,2 김진규,3 송상훈,2 서울대학교의과대학검사의학교실, 분당서울대학교병원진단검사의학과 2, 서울대학교병원진단검사의학과 3 Performance Evaluation of the Piccolo xpress Point-of-care Chemistry Analyzer Hyunwoong Park, M.D.,2, Dae-Hyun Ko, M.D.,2, Jin Q Kim, M.D.,3, and Sang Hoon Song, M.D.,2 Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul; Department of Laboratory Medicine 2, Seoul National University Bundang Hospital, Seongnam; Department of Laboratory Medicine 3, Seoul National University Hospital, Seoul, Korea Background : Point-of-care (POC) tests are used increasingly due to fast results and simple test procedures, which enables rapid diagnosis and therapeutic monitoring. We evaluated the performance of the Piccolo xpress Chemistry Analyzer (Abaxis, USA) a POC chemistry analyzer. Methods : Fourteen analytes, Na +, K +, Cl -, Ca 2+, total carbon dioxide, AST, ALT, total bilirubin, alkaline phosphatase, blood urea nitrogen, creatinine, albumin, total protein, and glucose; were measured simultaneously with a μl of whole blood sample using a Comprehensive Metabolic Reagent disk. Within-run and total precision and linearity were evaluated according to CLSI EP5-A and EP6-A guidelines, respectively. Comparison with a central laboratory chemistry analyzer was performed using 44 patient samples. Results : The coefficients of variations of within-run and total precision were all within 5% for three levels except for total carbon dioxide, ALT, alkaline phosphatase, total bilirubin, and creatinine in low level, and creatinine in middle level. The results of 4 analytes were linear within a commonly encountered range in clinical samples (r 2.98). More than % of samples in Na +, AST, ALT, glucose, BUN did not satisfy CLIA analytical quality requirement. Conclusions : The Piccolo xpress Chemistry Analyzer can analyze multiple analytes with a minimal amount of whole blood in a short time. It showed an acceptable performance for precision, linearity and comparison with central laboratory analyzer. It can be useful as a screening tests modality in mobile clinics, ambulances, and field clinics for military use, and for pediatric patients from whom enough sample volume is difficult to obtain. (Korean J Lab Med 29;29:43-8) Key Words : Point-of-care systems, Analytical chemistry, Evaluation studies 서 론 현장검사 (Point of care testing, POCT) 란중앙검사실을벗 Received : June 29, 29 Manuscript No : KJLM9-82 Revision received : August, 29 Accepted : September 8, 29 Corresponding author : Sang Hoon Song, M.D. Department of Laboratory Medicine, Seoul National University Bundang Hospital, 3 Gumi-dong, Bundang-gu, Seongnam 463-77, Korea Tel : +82-3-787-7693, Fax : +82-3-787-45 E-mail : cloak2@snu.ac.kr 어나진료가이루어지는장소에서시행되는진단검사로지난 2년동안그적용범위가늘어나고있다 []. 신속하게결과를보고할수있는현장검사는환자의진단과치료에빠르게적용할수있으며, 채혈량을줄임으로써환자들의만족도향상에기여하며, 더많은환자를진료하여야하는임상의사들의신속한검사결과의요구에도부합한다. 현장검사는여러장점들로인하여세계체외검사시장의약 3분의 을차지하고있으며매년 9% 씩성장하고있다 []. 또한국내에서는 22년한해동안에진단검사시장의 7.8% 를현장검사가차지하였다 [2]. 진단검사 43
Evaluation of Piccolo xpress Chemistry Analyzer 43 의학과에서실시하는검사중약 6-7% 를차지하는분야가임상화학검사이며, 이중전해질검사와간기능검사, 신기능검사, 혈당검사는대부분의의료환경에서기본적인환자의상태를알수있는검사로매우중요하다 [2]. 그러나혈당측정기를이용한혈당검사와동맥혈가스분석기에포함된전해질등의검사이외에포괄적으로임상화학검사가가능한현장검사장비는거의소개된적이없다. 본연구에서는임상화학현장검사장비인 Piccolo xpress Chemistry Analyzer (Abaxis, Union city, CA, USA) 를이용하여나트륨 (Na + ), 칼륨 (K + ), 염소 (Cl - ), 칼슘 (Ca 2+ ), 총이산화탄소 (total carbon dioxide, tco 2 ), AST, ALT, 알칼리인산분해효소 (alkaline phosphatase, ALP), 총빌리루빈 (total bilirubin), 알부민 (albumin), 총단백질 (total protein), 혈액요소질소 (blood urea nitrogen, BUN), 크레아티닌 (Cr), 혈당 (glucose) 농도를측정하여수행능을평가하였다. 재료및방법. 장비및시약 Piccolo xpress Chemistry Analyzer는전혈, 혈장, 혈청검체에대하여 2분이내에 24종의화학검사항목의패널에대하여검사를시행한다. 원심분리를할필요가없이원하는검사항목의패널에 μl 의검체를넣어준후기계에삽입하면자동으로모든검사가이루어지며, 매검사시마다기계의화학적, 광학적, 전자적인성능이적합한지확인하며, 검체량이적합한지, 검체의용혈, 황달혈, 지질혈여부를확인한다. Piccolo xpress Chemistry Analyzer는사용되는패널디스크의종류에따라서 2가지에서 4가지항목의검사를시행할수있다. 약 32 2 5 cm 의크기로이동이가능하며 5 volt 전원의공급으로작동이가능하다. 검체는 μl 의전혈, 혈장, 혈청모두가능하며약 2 분이내에결과를확인할수있다. 각항목의측정가능범 A B C D E Fig.. Measuring sequence of Piccolo xpress Chemistry Analyzer. (A) Blood sample is applied and diluent container is opened. (B) Diluent and blood sample enter the quality control cuvettes and blood sample enters the centrifugal chamber. (C) Centrifuge is performed. (D) Centrifuged sample and diluent are mixed. (E) The assay cuvettes are filled and analysis is performed (This schematic diagram was permitted from Abaxis system).
432 박현웅 고대현 김진규외 인 위는 Na + 7 mmol/l, K +.5-8.5 mmol/ L, Cl - 835 mmol/l, Ca 2+ 4.6. mg/dl, tco 2 5-4 mmol/l, AST 5-2, U/L, ALT 5-2, U/L, ALP 5-2,4 U/L, total bilirubin.-3 mg/dl, glucose -7 mg/dl, BUN 2-8 mg/dl, Cr.2-2 mg/dl, albumin -6.5 g/dl, total protein 24 g/dl로임상적으로충분한범위를포함하고있다. Piccolo xpress Chemistry Analyzer의검사순서는 μl 의검체를디스크에삽입하면검체의일부와반응희석시약의일부가큐벳 (cuvette) 에서검체의용혈, 황달혈, 지질혈여부를확인하며반응시약에대한적절성평가가이루어진다. 그후, 검체는원심분리가이루어지며, 반응희석시약과혼합되며, 각반응큐벳으로이동하여각검사항목에대하여측정이이루어진다 (Fig. ). 각항목별측정원리는 Table 과같다. 본연구에서는 4종의 Comprehensive Metabolic Panel 디스크를사용하였다. 2. 정밀도 (Precision) 정밀도의평가는 Clinical and Laboratory Standards Institute (CLSI) EP5-A2에준하여정도관리물질 Liquid Unassayed Multiqual (Bio-Rad Laboratories, Irvine, CA, USA) 을이용하여 5일간하루에 2회씩매검사마다 2회씩반복측정하여검사차례내정밀도와총정밀도를구하였다 [3]. Cl - 의경우상기정도관리물질의저농도가 Piccolo xpress Chemistry Analyzer의측정가능범위보다낮았기때문에저농도와중간농도를 3:2로혼합한물질을제조하여저농도로사용하였다. 또한 Table. Principles of procedures of Piccolo xpress Chemistry Analyzer Analyte Albumin ALP ALT AST BUN Ca 2+ Cl - Creatinine Glucose K + Na + tco2 Total bilirubin Total Protein Principle Dye-Binding BCP PNPP, AMP buffer UV without P5P UV without P5P Urease with GLDH (coupled enzyme) Arsenazo III Dye Enzymatic Reaction (activation of α-amylase) Enzymatic Reaction (creatinine amidohydrolase/ Sarcosine oxidase) Hexokinase, Colorimetry Enzymatic Reaction (activation of pyruvate kinase) Enzymatic Reaction (activation of β-galactosidase) Enzymatic Reaction (PEPC) Enzymatic bilirubin oxidase Biuret Abbreviations: ALP, alkaline phosphatase; BUN, blood urea nitrogen; tco2, total carbon dioxide. 실제환자검체 개를임의로선택하여 회반복측정을실시하여전혈에서의검사차례내정밀도를평가하였다. 3. 직선성 (Linearity) 직선성의평가는 CLSI EP6-A에준하여평가하였다 [4]. 저농도로사용할물질은상기 4 종목의저농도의환자검체를선별하였으며, AST, ALT, ALP, total bilirubin, tco 2, BUN, Cr 의항목은고농도의환자검체를선별하였다. Na +, K +, Cl -, Ca 2+, glucose, albumin, total protein은 Piccolo xpress Chemistry Analyzer의측정상한값에이르는환자검체를선별할수없었기때문에환자혈청에측정상한값보다조금낮도록 NaCl (Sigma-Adrich Co., St. Louis, MO, USA), KHCO 3 (Samchun pure chemical Co., Ltd., Pyeongtaek, Korea), calcium gluconate (Daehan Pharm Co., Ltd., Seoul, Korea), D-(+)-glucose (Sigma-Aldrich Co., St. Louis, MO, USA), albumin (Sigma-Aldrich Co., St. Louis, MO, USA) 을적당량첨가하여 Na + 6 mmol/l, Cl - 25 mmol/l, K + 8.3 mmol/l, Ca 2+ 6. mg/dl, glucose 495 mg/dl, albumin 6.2 g/dl, total protein 9.3 g/dl의고농도혈청을제조하였다. 준비된저농도고농도의혈청에각각 O형적혈구를헤마토크릿이 32-34% 가되도록혼합하여전혈을제조하였다. 그후저농도와고농도의전혈을각각 4:, 3:, 2:2, :3, :4 의비율로혼합한 5가지단계물질을제조한후각각의단계에대하여 TBA 2-FR (Toshiba Co., Tokyo, Japan) 으로농도를측정하였으며, Piccolo xpress Chemistry Analyzer로 4회씩반복측정하여직선성의범위를확인하였다. 4. 상관성 (Method comparison) 상관성의평가는 CLSI EP9-A2에준하였다 [5]. 기준장비인 TBA 2-FR로측정한결과를기준으로 44개의리튬헤파린관에환자검체를수집하였다. 같은날동시에채혈된검체에대하여 TBA 2-FR에측정할검체는혈청분리관에운반하였고, Piccolo xpress Chemistry Analyzer에측정할검체는리튬헤파린관으로운반하여전혈상태로측정하였다. 5. 통계처리통계처리는 Excel 23 (Microsoft Corporation, Redmond, WA, USA) 와 EP evaluator 8 (David G. Rhoads Associates,
Evaluation of Piccolo xpress Chemistry Analyzer 433 Inc., Kennett square, PA, USA) 프로그램을이용하였다. 직선성의평가에는선형회귀분석을이용하였고회귀방정식과결정계수를구하였다. 상관성의평가에는 Deming 회귀분석을시행하여회귀선의기울기, 절편, 상관계수를구하고 TBA 2- FR을기준으로한오차의평균과표준편차를구하였다. 결과. 정밀도저농도, 중간농도, 고농도의정도관리물질에대한 Na +, K +, Cl -, Ca 2+, tco 2, AST, ALT, ALP, total bilirubin, albumin, total protein, BUN, Cr, glucose 항목의검사차례내및총변 Table 2. Precision of the Piccolo xpress Chemistry Analyzer by Liquid Unassayed Multiqual Analytes (unit) Cases N Mean Within-run SD CV (%) Total SD CV (%) Na + (mmol/l) Low 2.6.44.3.33.2 Middle 2 38.7.53. 2.22.6 High 2 57.9.74. 2.5.3 K + (mmol/l) Low 2 2..8 3.9.7 3.5 Middle 2 3.8.9 2.4. 2.5 High 2 7..6 2.3.6 2.2 Cl - (mmol/l) Low 2 85.5.95..7.25 Middle 2 98.27.3.76.8 High 2 4.3.7.5.7.5 Ca 2+ (mg/dl) Low 2 5.8.27 4.6.26 4.5 Middle 2 9.4.25 2.7.23 2.4 High 2.7.46 3.9.43 3.7 tco2 (mmol/l) Low 2 7.5. 5.7.98 5.6 Middle 2 23.8.98 4..9 4.6 High 2 29.2.34 4.6.3 4.5 AST (U/L) Low 2 4.94 2.3.5 2.8 Middle 2.4.3.3.2.2 High 2 28.9.75.8 2.63.2 ALT (U/L) Low 2 28.9 3.9.7 3.5 2. Middle 2 77.9 2. 2.7 2.65 3.4 High 2 63.4 3.27 2 3.43 2. ALP (U/L) Low 2 34 3.47.2 3.9 9. Middle 2 8.7 4.36 2.4 4.8 2.3 High 2 39.7 5.86.5 5.8.3 Total bilirubin Low 2.6.5 7.8.5 8 (mg/dl) Middle 2 2.8.4.3.7 2.5 High 2 6.3.8.2..7 Albumin (g/dl) Low 2 2.8.9 3.2. 3.5 Middle 2 3.7. 2.9. 2.9 High 2 4.5.7.5. 2.2 Total protein Low 2 4.2.9 2..8 2 (g/dl) Middle 2 5.6.5.9.5.9 High 2 7..9.2.9.3 BUN (mg/dl) Low 2 4.5.52 3.6.52 3.6 Middle 2 35.9.93 2.6.9 2.5 High 2 66.5.67.6.6 Creatinine Low 2.7. 5..9 3.3 (mg/dl) Middle 2.9. 5.9. 5.6 High 2 6.4.2.8..6 Glucose Low 2 66.7.53 2.3.87 2.8 (mg/dl) Middle 2 26..88.7.3.9 High 2 359.2 2.5.7 2.87.8 Abbreviations: tco2, total carbon dioxide; ALP, alkaline phosphatase; BUN, blood urea nitrogen.
434 박현웅 고대현 김진규외 인 이계수는대부분우수하였다 (Table 2). 저농도에서는 tco 2, ALT, ALP, total bilirubin, Cr의검사차례내및총변이계수가 5% 를넘었으며, 나머지 9개의항목에서는 5% 미만이었다. 중간농도에서는 Cr만이검사차례내및총변이계수가 5% 정도였으며, 나머지 3개의항목모두 5% 미만이었다. 고농도에서 는모든항목의변이계수가 5% 미만으로우수하였다. 모든항목에서의검사차례내변이계수와총변이계수는차이가없었다. 실제환자검체를이용하여 회반복측정하였을때에도검사차례내변이계수는정도관리물질을사용하였을때와비교하여유의한차이를보여주지는않았다. Table 3. Linearity of the Piccolo xpress Chemistry Analyzer Analytes Unit Range Slope Intercept R 2 Analytes Unit Range Slope Intercept R 2 Na + mmol/l 32.262.3. <..99 K + mmol/l 4.3-8.3. <..982 Cl - mmol/l.323.. <..9759 Ca 2+ mg/dl 9.34.8. <..9955 tco2 mmol/l 9.3-3.5. <..9829 AST U/L 25.8,93.3. <..9998 ALT U/L 2.,93.8. <..9999 ALP U/L 29.5-827.5. <..9997 Total bilirubin mg/dl.6-5.. <..9995 Glucose g/dl 74.-495.8. <..9999 BUN g/dl 8.3-5.5. <..9987 Creatinine mg/dl.6-8.9. <..9988 Albumin mg/dl 3.7-5.7. <..9933 Total protein mg/dl 7.-9.. <..995 Abbreviations: tco2, total carbon dioxide; ALP, alkaline phosphatase; BUN, blood urea nitrogen. Table 4. Correlations between Piccolo xpress Chemistry Analyzer and TBA 2-FR Analytes Unit Range Slope (95% CI) Intercept (95% CI) (Mean±SD) P value* % (Mean±SD) CLIA requirement Percent of samples not satisfying CLIA requirement R Na + mmol/l 7.977 6. 2.9±4. <. 2.±3.2 Target±4 34.7.9355 (.99.36) (-2.4.2) K + mmol/l 2.9-8.5.968.9.±.2.98.8±5. Target±.5.4.9874 (.942-.993) (.5-.33) Cl - mmol/l 833.943 4.8.4±2.8 <..3±2.6 Target±5% 4.2.9748 (.97-.978) (.-8.7) Ca 2+ mg/dl 6.46..955.75.3±.5 <. 3.4±5.5 Target±. 3.5.9879 (.93-.98) (.49.) tco2 mmol/l -37.696 9.4 2.3±3.5 <..9±6.5 NA NA.6534 (.592-.799) (7..9) AST U/L 6-269.889.8 8.±5. <. 4.9±28.2 Target±2%.5.9966 (.877-.92) (.22.4) ALT U/L 8-56.846.2 5.5±.9 <. 47.6±56. Target±2% 42.7.9965 (.834-.858) (.42.) ALP U/L 3-6.798 5.4 9.4±25.4 <. 3.4±7. Target±3%.996 (.786-.8) (3.4-7.4) Total mg/dl.43.4.92.7.±.23.6 9.5±26.8 Target±.4 or.4.9973 bilirubin (.89-.93) (.5-.2) ±2% (greater) Glucose g/dl 44-45.938 -.5-7.9±9.4 <..9±58.2 Target±6 or 25..995 (.96-.96) (-3.5-2.5) ±% (greater) BUN g/dl 5.982 -.9.3±.4 <. -6.3±.8 Target±2 or 4.7.9963 (.968-.997) (.3~-.6) ±9% (greater) Creatinine mg/dl.2.8.45 -.26 -.2±.2 <. -2.±5.9 Target±.3 or 2.2.9978 (.33.57) (-.28~-.23) ±5% (greater) Albumin mg/dl.6-4.9.58 -.6 -.4±.2 <..±6.9 Target±% 3.5.9646 (..5) (-.8~-.42) Total mg/dl 4.3-9.5.8 -.34.2±.3 <. 3.±4. Target±% 2.8.952 protein (.24.36) (-.72-.4) *P values were determined by using the paired t-test. Percentage of the samples which does not satisfy CLIA requirement derived from the regression equation. Abbreviations: tco2, total carbon dioxide; ALP, alkaline phosphatase; BUN, blood urea nitrogen.
Evaluation of Piccolo xpress Chemistry Analyzer 435 2. 직선성 3. 상관성 상기 4 항목은임상검체에서흔하게측정되는범위에서대체적으로만족할만한직선성을나타냈다 (Table 3). 결정계수는 K + 의r 2 =.98, Cl - 의r 2 =.98, tco 2 의r 2 =.98인것을제외하고 항목모두의 r 2 =.99 이상이었다. Piccolo xpress Chemistry Analyzer와 TBA 2-FR과의상관성평가결과 Na + 과 tco 2 를제외하고 2개항목의상관계수가모두.95 이상이었다 (Table 4, Fig. 2). Na + 과 tco 2 의상관계수는각각.94,.65이었다. 4개항목의회귀곡선의기 Na + K + CI - Ca 2+.5 (mmol/l) 5-5 (mmol/l).5 -.5 (mmol/l) 5-5 (mg/dl).5 -.5 2 4 6 8 Toshiba (mmol/dl) 2 3 4 5 6 7 8 Toshiba (mmol/dl) 8 9 2 3 4 Toshiba (mmol/dl).5 5 7.5 2.5 5 5 TCO2 3 AST ALT ALP 5 (mmol/l) 5-5 5 2 3 4 Toshiba (mmol/l) (U/L) 2-2 -3 5 5 2 25 3 Toshiba (U/L) (U/L) 5-5 2 4 6 Toshiba (U/L) (U/L) 5-5 5 2 4 6 8 Toshiba (U/L).5 Total Bilirubin Glucose BUN Creatinine 4 (mg/dl).5 -.5 (mg/dl) 2-2 (mg/dl) 5-5 (mg/dl).5 -.5.5 5 5-4 2 3 4 5 25 5 75 2.5 5 7.5 Albumin Protein (g/dl).5 -.5 2 3 4 5 Toshiba (g/dl) (g/dl).5 -.5 4 5 6 7 8 9 Toshiba (g/dl) Fig. 2. Correlations of 4 analytes of Comprehensive Metabolic Reagent disk between Piccolo xpress Chemistry Analyzer and TBA 2-FR. Dashed line indicates mean bias. Abbreviations: tco2, total carbon dioxide; ALP, alkaline phosphatase; BUN, blood urea nitrogen.
436 박현웅 고대현 김진규외 인 울기는.7에서.8이었으며, 평균오차와그통계적의미는 Table 4와같았다. 고찰전혈을이용한현장검사를이용하면임상진료진이응급상황에서빠른결과를도출할수있으므로즉각적인판단과치료에도움이된다 [6]. 특히응급상황에서검체운반시간과검체가바뀌는등의검사전오류를최소화할수있다. 대부분의현장검사장비들이소량의검체로도검사가가능하기때문에환자의혈액을낭비하지않는점에도도움이된다 [7]. 현장검사기기의장점들로인하여응급실, 중환자실, 수술실, 외래진료실, 가정등에서혈액가스분석기, 임신반응검사키트, 휴대용혈당측정기, 심장효소검사, 감염진단기기의사용이증가하는추세이다 []. 특히가장기본이되는화학검사결과는병원에도착하기전의구급차혹은야외진료소에서환자의응급한정도를구별하는데크게기여할수있다 [8]. Piccolo xpress Chemistry Analyzer의분석능력평가결과, 정도관리물질을이용한정밀도평가의경우낮은농도에서의 tco 2, ALT, ALP, total bilirubin, Cr, 중간농도의 Cr을제외한모든항목의검사차례내및총변이계수가 5% 미만이었다. 각검사항목별정밀도변이계수의목표값은저농도와중간농도, 고농도에서의값을각각모두설정할수는없었으나 Na +.3-.4%, K + 2.2-3.7%, Cl -.3.6%, Ca 2+.8-.86%, tco 2 3.2-4.%, AST 6.%, ALT.32.7%, ALP 3.2%, total bilirubin 6..5%, glucose 2.7-3.2%, BUN 6.2%, Cr 4.- 5.4%, albumin 3.5-3.7%, total protein 2.-2.9% 로설정하였다 [9]. 이에따라서각항목을평가해보면, 저농도, 중간농도, 고농도에서 Na +, K +, Cl -, AST, ALT, total bilirubin, glucose, BUN, Cr, albumin, total protein의 가지항목에서정밀도변이계수가목표값내에있었다. 그러나 Ca 2+ 의변이계수가 2.7-4.6%, tco 2 4.-5.7%, ALP의저농도에서변이계수가.2% 로정밀도변이계수의목표값보다약간높았기때문에임상에서적용시주의가필요할것이다. 정밀도변이계수의목표값으로설정에는포함되었으나저농도에서 5.% 의변이계수를보인 Cr의경우본기기의검사법 (creatinine amiodohydrolase/sarcosine oxidase 반응후생성된 H 2 O 2 을 peroxidase로 dye를측정 ) 과유사한 (creatinine amiodohydrolase/ sarcosine oxidase 반응후생성된 H 2 O 2 을전극에서전압을측정 ) 현장검사기기로측정한결과총변이계수가저농도에서 3.8%, 고농도에서 9.5% 이었다는보고가있다 [6]. 또다른현장 검사기기의연구에서도 Cr의변이계수는 4개의연구센터에서측정한결과총변이계수가 4.7-9.4% 이었다는보고가있다 [2]. Cr의경우임상적으로문제가되는경우는대부분높은농도이고선별검사를위해서주로사용한다면실제사용하는데에는큰문제는없을것으로생각된다. 환자의전혈을이용하여 회반복측정한정밀도평가에서도정도관리물질을이용하여측정한결과와거의차이가없었다. Cr의경우에변이계수가 9.6% 이었으나이는농도가낮기때문으로평균은.58 mg/dl, 표준편차는. mg/dl이었다. 직선성평가에서 4항목모두에서넓은측정범위에서결정계수 (R 2 ) 가.98 이상으로우수하였다. 특히 K +, Cl -, tco 2 를제외한 가지항목에서는모두결정계수가.99 이상으로매우우수하였다. 또한중앙검사실의 TBA 2-FR과의비교평가에서 Na +, tco 2 를제외한 2가지항목에서상관계수가모두.95 이상으로높은상관성을보여주었다. 상관계수에대하여 Zady의평가기준에따르면, tco 2 의항목은 moderate correlation, 나머지 3항목은 very high correlation으로분류할수있었다 [3]. 또한K + 항목을제외한 3항목에서유의확률이 <.로유의한관계를보였다. Na + 과 tco 2 의항목에서상관계수가.94와.65 로낮은이유로는중앙검사실의방법과측정원리가다르거나측정한값의범위가좁기때문일것으로생각된다. 각항목을회귀방정식을구한결과에맞추어값을변경한후, CLIA에서요구하는수행능에맞춰평가한결과 Na +, AST, ALT, glucose, BUN의경우 CLIA의요구조건에부합하지않는검체가 % 이상인점은임상에서의사용시에주의가필요할것으로생각된다 [4]. 본연구에서사용한장비는임상에서가장흔하게의뢰하는검사들을패널디스크로구성하여동시에여러항목을측정할수있는장점이있다. 특히소량의검체를사용하기때문에상대적으로혈액량이적고혈액을채취하기어려운신생아검사에서유용하게사용할수있다. 신생아의소량의검체로검사가가능한장비로는 i-stat (i-stat Corporation, Princeton, NJ, USA), Stat Profile Critical Care Xpress analyzer (STP CCX; Nova Biomedical, Waltham, MA, USA) 등이있으나검사가능한화학검사항목이본장비보다많지않다 [5, 6]. 본장비에서 EDTA, 헤파린나트륨, 구연산등의항응고제는 Na +, K +, Ca 2+ 의결과에영향을미치기때문에각패널에포함된검사항목을고려하여항응고제를선택해야한다. 전혈을이용한검사에서미국식품의약국에서검사실밖에서도측정가능한 POCT 장비용으로승인받은항응고제가리튬헤파린인데상기검사항목들에대한영향을최소화시키기위한것으로생각된다. 국내에
Evaluation of Piccolo xpress Chemistry Analyzer 437 서리튬헤파린을항응고제로사용하는기관이많지않기때문에 EDTA 검체를사용하는것을고려해볼수있다. 저자들이예비실험한바에의하면 AST, ALT, albumin, total protein, BUN, Cr, glucose은차이가 5% 미만이었다. 그러나 Na +, K + 에서는평균 9. mmol/l, 2.3 mmol/l 이상으로일관되게높게측정되었고, Ca 2+, ALP에서는거의대부분의검체에서검출한계미만으로측정되었다. Ca 2+ 이낮게측정되는것은 EDTA 의킬레이트효과로쉽게예측할수있고, K + 이높게측정되는것도 EDTA가칼륨염의형태로첨가되어있기때문으로생각된다. 그리고 EDTA는금속이온을킬레이션하여여러효소에억제제로작용할수있음이알려져있는데, ALP에도역시억제작용을해그측정값을떨어뜨리는것으로알려져있다 [7]. Na + 이높게측정되는원인은명확하지않으며이에관해서는좀더연구가필요할것으로생각된다. 이런결과들로보아, 임상현장에서위의항목들을제외한 항목중에서만필요한검사항목이있을경우, EDTA 채혈관으로도무리없이검사를수행할수있을것으로보인다. 정맥혈뿐만아니라모세혈관혈액도 μl 이상을채혈할수있으면측정이가능한데최근에출시되는대부분의혈당측정기에서 μl 이하의혈액을채취하므로바늘형태의천자도구보다는란셋형태의천자도구를사용하는것을고려해볼수있으며이러한접근법의가능성에관한검증이필요하다. 내부정도관리는적절한정도관리물질을사용할수있으며검사실밖에서도측정가능한 POCT 장비용으로사용할경우에는최소 3일이내에한번, 검사실환경에서사용할경우에는검사실의방침에따라시행하도록권장하고있다. 장비의기본적인화학적, 광학적, 전자적인기능은매검사가시작될때에자동으로확인하는 intelligent quality control (iqc) 기능이내장되어있으므로별도의관리가필요없기때문에검사실밖에서도유용하게사용할수있다. Piccolo xpress Chemistry Analyzer는정밀도, 방법간비교, 직선성평가에서대체적으로우수한성능을보였다. μl 의소량의전혈을이용하여원심분리할필요가없이 2분이내의빠르고신뢰성있는 4종의화학분석결과를제공함으로써이동식진료실, 응급후송차, 군대의야전진료소와많은양의채혈이어려운소아환자검사등에서유용할것으로생각한다. 요약배경 : 현장검사는신속하고간편하여환자의진단과치료효과판정에빠르게적용할수있기때문에점차그적용범위가늘 어나고있다. 저자들은현장검사화학분석장비인 Piccolo xpress Chemistry Analyzer (Abaxis, USA) 의성능을평가하였다. 방법 : Comprehensive Metabolic Reagent 디스크에 mcl의검체를이용하여 4가지항목 ( 나트륨, 칼륨, 염소, 칼슘, 총이산화탄소, AST, ALT, 알칼리인산분해효소, 총빌리루빈, 혈당, 혈액요소질소, 크레아티닌, 알부민, 총단백질 ) 을동시에측정하였다. 검사차례내정밀도와총정밀도는 CLSI EP5-A 에준하여평가하였으며, 직선성은 CLSI EP6-A에준하여평가하였다. 중앙검사실장비와의상관성은 44개의환자검체를이용하여평가하였다. 결과 : 검사차례내정밀도와총정밀도의변이계수 (CV) 는낮은농도의총이산화탄소, ALT, 알칼리인산분해효소, 총빌리루빈, 크레아티닌과중간농도의크레아티닌을제외하고모두 5% 미만이었다. 4가지항목의측정값은임상검체에서흔하게나타나는범위에서직선성을유지하였다 (r 2.98). 그러나나트륨, AST, ALT, 혈당, 혈액요소질소의경우 CLIA의수행능평가요구조건에부합하지않는검체가 % 이상인점은임상환경에서사용시주의가필요하다. 결론 : Piccolo xpress Chemistry Analyzer는소량의전혈로짧은시간에여러항목을측정할수있다. 정밀도, 직선성, 중앙검사실장비와의상관성은수용할만하였다. Piccolo xpress Chemistry Analyzer는이동식진료실, 응급후송차, 군대의야전진료소와많은양의채혈이어려운소아환자검사등에서유용할것으로생각한다. 참고문헌. Nichols JM. Point of care testing. Clin Lab Med 27;27:893-98. 2. Min WK. The trend of clinical chemistry. Medical Postgraduates 23;3:25-4. ( 민원기. 임상화학의현황. 녹십자의보 23;3:25-4.) 3. Clinical and Laboratory Standards Institute. User verification of performance for precision and trueness; Approved guideline-2nd edi. Document EP5-A2. Wayne, PA: Clinical and Laboratory Standards Institute, 25;25. 4. Clinical and Laboratory Standards Institute. Evaluation of the linearity of quantitative measurement procedures: a statistical approach; Approved guideline. Document EP6-A. Wayne, PA: Clinical and Laboratory Standards Institute, 23;23. 5. Clinical and Laboratory Standards Institute. Method comparison and bias estimation using patient samples; Approved guideline- 2nd edi. Document EP9-A2. Wayne, PA: Clinical and Laboratory
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