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1 대한내과학회지 : 제 76 권제 5 호 2009 만성폐쇄성폐질환의폐기능검사와운동검사의비교 건양대학교의과대학내과학교실, 명곡의과학연구소 나운태 박주호 이고은 권선중손지웅 나문준 최유진 Comparison of spirometry with cardiopulmonary exercise test of chronic obstructive pulmonary disease Woon-Tae Na, M.D., Joo-Ho Park, M.D., Go-Eun Lee, M.D., Sun-Jung Kwon, M.D., Ji-Woong Son, M.D., Moon-Jun Na, M.D. and Eu-Gene Choi, M.D. Department of Internal Medicine, College of Medicine, Konyang University, Konyang University Myunggok Research, Daejon, Korea Background/Aims: Chronic obstructive pulmonary disease (COPD) is characterized by an incompletely reversible airflow limitation. Pulmonary function test (PFT) has been considered the gold standard test for diagnosis and severity evaluation in COPD. However, PFT by spirometry does not provide information about exercise performance in COPD patients. Therefore, the present study was performed to compare pulmonary function determined by spirometry with exercise function determined by cardiopulmonary exercise test (CPET) for grading of COPD. Methods: A total of 105 patients with airway obstruction were examined. The patients mean age was 65 years, and the mean smoking history was 27 pack-years. The patients underwent spirometry and CPET. The results were analyzed by categorical statistical comparison, based on the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and American Thoracic Society guidelines. Results: The two methods agreed on the classification of only 44 patients (42%). Of the remaining patients, 21 (20%) were found to be less severe according to CPET than according to PFT, whereas 40 (38%) were more severe. Those who were more severe according to CPET had significantly low maximal minute ventilation, low anaerobic threshold, low oxygen pulse, and high breathing reserve. Conclusions: The present study revealed the large disagreement between the results of resting and exercise pulmonary function tests, and therefore suggests the need for a novel approach or guideline. Additional cardiological evaluation may be needed in patients classified as more severe according to CPET, who are assumed to have a greater degree of impairment of cardiovascular function. (Korean J Med 76: , 2009) Key Words: Chronic obstructive pulmonary disease; Exercise test; Spirometry Received: Accepted: Correspondence to Eu-Gene Choi, M.D., Department of Internal Medicine, Konyang University Hospital, 685 Gasoowon-dong, Seo-gu, Daejon , Korea eugene@kyuh.co.kr * This work was supported by Konyang University Myunggok Research Fund of

2 - The Korean Journal of Medicine: Vol. 76, No. 5, 서 론 대상및방법 COPD의장애정도와질병의중증도 (severity) 를평가하고결정하는것은의학적인영역뿐만아니라사회적, 경제적그리고보건행정상의많은영역과연관되어있는중요한문제이다. 또한그평가는환자가병원밖실생활을영위해나가는데있어서의기능제한에초점을맞추어야할필요성도있다. COPD의중증도를평가하기위해서일반흉부사진, 일반폐기능검사, 동맥혈가스분석, 흉부전산화단층촬영및운동부하심폐기능검사등의방법들이이용되어왔다. 이중에서안정상태에서폐활량계 (spirometer) 를이용하여시행되는폐활량검사가호흡기능의손상과장애정도를평가하고질병의중증도를결정하는데일반적으로가장많이시행되는표준적인검사로서자리매김해왔다. ATS (American Thoracic society) 의진료지침 (guideline) 이나최근발표된 GOLD (Global Initiative for Chronic Obstructive Lung Disease) 진료지침도이를기준으로삼고있다 1,2). 하지만이러한안정시의폐활량계를이용한일반폐기능검사만으로는환자가실생활에서겪는활동시의장애 (disability) 정도와운동내성 (exercise capacity) 의한계등을평가하고예측하는데는무리가있다 3-5). 운동내성이반영되는폐기능검사도구중에서널리사용되는방법중하나가운동부하심폐기능검사이다. 운동부하심폐기능검사는호흡기계를포함하여순환기계, 조혈계, 신경정신계, 근골격계의운동에대한반응을종합적으로평가할수있는도구이다 6). 이는최근 COPD가폐에국한된질환이아닌전신적인질환임이강조되고있으며, 그에대한평가도이를반영해야할필요성이있다는데에서도그의미가있다 7-9). 또한휴식상태의폐기능이같은환자들일지라도, 생활방식이나직업의특성, 환자의일중활동량등의개인차로인해, 실생활영역에서보일수있는호흡능력은차이가있기때문에운동역량에대한정량적인자료를이용하여신체의가스교환능력을평가하는운동부하심폐기능검사가 COPD 환자의전신상태를반영하고평가하는데있어여러장점도있다 7-9). 이에본저자들은 COPD 환자들의중증도를운동부하심폐기능검사와폐활량계를이용한일반폐기능검사를이용하여분류하고, 그결과를비교분석하였다. 대상환자는과거 COPD를진단받은환자중보행가능한 105명을대상으로하였다. COPD 의진단은 GOLD 진료지침에근거하여폐활량계를이용하여 1초간노력성호기량과강제호기용적의비 (FEV1/FVC) 가 70% 미만인경우로하였으며, 기관지확장증, 폐결핵, 천식환자는제외하였다. 대상환자중에서명백한심혈관계질환을진단받은과거력이있는환자나또는전신질환을가지고있는경우도연구대상에서제외하였다. 모든환자에게운동부하심폐기능검사당일에도평소와같은투약을하였다. 이들은일반폐기능검사를먼저시행받았고, 운동부하심폐기능검사는일반폐기능검사시행일로부터 14일이내에시행하였다. 검사시행일전후 1개월이내에입원치료를받은환자는대상에서제외하였다. 두가지검사는환자가앉은상태에서대기중 (room air) 에서시행하였다. 단순폐기능검사는 JAEGER사의 Master- Screen PFT (JAEGER company, Germany) 를이용하였다. 점진적운동부하검사는 Ramp protocol을이용해서전자식으로제어되는 cycle egometer (Ergometrics 800, Germany) 를이용하였다. 처음 3분간부하가없는상태에서패달을밟는연습후에일분당 5~10 watts 씩부하를상승시켰다. 모든대상은호흡곤란과같은불편감을심하게느끼거나, 근육이나전신의피로감같은탈진증상을보일때까지검사를진행하도록하였고, 심전도에서이상소견이나타나거나, 생체징후에이상이발생하면즉시검사를중단하도록하였다. 최대심박동수 (Maximal heart rate; HRmax), 분당환기량 (minute ventilation; VE), 산소섭취량 (Oxygen consumption; VO 2), 이산화탄소생산량 (Carbon dioxide production; VCO 2) 그리고 Oxygen pulse (VO 2/HR) 등의항목이측정되었으며, 맥박산소측정기를이용한동맥혈혈색소의산소포화도도측정되었다. 각평가항목에대한예측치는 Karlman 등의저서를참고하였다 10). 호흡예비능 (Breathing reserve) 은최대자발호흡 (MVV) 과최대운동시얻어지는분당환기량 (VE) 의차이 (MVV-VE) 로정의하였다. 혐기성역치는 (Anaerobic threshold; AT) 는 V-slope method로결정하였다 11). 가스분석기의점검은각각의검사이전에수행되었고, 이는제조사의표준점검양식을이용하였다. 모든기류와가스측정치는주위공기의온도와기압, 수증기에대해서보정되었다. 일반폐기능검사와운동부하심폐기능검사의결과는각각독립적으로분류되었고, 분류단계는 Grade I (mild), Grade II (moderate), Grade III (severe), Grade IV (very severe) 의 4단계로나누었다. 분류의기준은

3 - Woon-Tae Na, et al. Comparison of spirometry with CPET of COPD - Table 1. Classification of patients with chronic obstructive pulmonary disease by pulmonary function and cardiopulmonary exercise tests Degree of severity FEV 1 of PFT (% pred)-gold FEV 1 of PFT (% pred)-ats VO 2max of CPET (ml/kg/min) Grade I 80% 80% 25 ml/kg/min Grade II 50-79% 60-79% ml/kg/min Grade III 30-49% 40-59% ml/kg/min Grade IV <30% <40% <15 ml/kg/min % pred, percentage of predicted value; ATS, American Thoracic Society; CPET, cardiopulmonary exercise test; FEV 1, forced expiratory volume in the first second; GOLD, Global initiative for Chronic Obstructive Lung Disease; PFT, pulmonary function test; VO 2max, maximal oxygen consumption. Table 2. Demographic data in 105 ambulatory patients with chronic obstructive pulmonary disease Variable Mean±SD Age (years) 65.4±7.9 Height (cm) 161.9±8.1 Weight (kg) 56.5±9.2 BMI (kg/m 2 ) 1.58±0.14 Smoking (n, %) Smoking (pack-years) BMI, body mass index. 86 (81.9%) 27± 년발표된 ATS 진료지침과 GOLD 진료지침을참고하였다 1,2,12). 일반폐기능검사결과에서는 GOLD 진료지침에의한경우는 1초간노력성호기량이예측치의 80% 이상인경우에는 Grade I로, 50~79% 인경우에는 Grade II, 30~49% 인경우에는 Grade III, 30% 미만인경우에는 Grade IV로분류하였다 ( 표 1). 운동부하심폐기능검사결과에서는최대산소섭취량 (VO 2Max) 가 25 ml/kg/min 이상인경우는 Grade I, 20~25 ml/kg/min 인경우는 Grade II, 15~20 ml/kg/min 인경우는 Grade III, 15 ml/kg/min 미만인경우는 Grade IV로분류하였다 ( 표 1). 통계학적분석은 SPSS version 12.0K를이용하였다. 일반폐기능검사결과와운동부하심폐기능검사의결과는평균 ±1 표준편차로표시하였다. 두가지검사에서연속변수의평균비교는 t-test를이용하였다. p<0.05 인값을보이는경우에통계적으로유의한것으로정의하였다. 결 COPD로진단되어포함된대상환자총 105명의평균나이는 65.4±7.9세였고, 평균체질량지수는 1.58±0.14였으며, 과거또는현재흡연자는 86명 (81.9%) 이었는데평균 27갑년 과 Table 3. Pulmonary function and cardiopulmonary exercise test results of 105 ambulatory patients with chronic obstructive pulmonary disease Variable Mean±SD FEV 1 (%) 58.3±17.4 MVV (L/min) 51.0±16.8 DLCO (%) 53.7±18.4 VO 2max (% pred) 68.4±22.8 VO 2max (ml/kg/min) 17.6±6.04 O 2 pulse (% pred) 82.1±25.0 VE (L/min) 38.1±14.1 BR (L/min) 12.9±14.8 SaO 2 (%) 90.5±9.72 BR, breathing reserve; DLCO, diffusion capacity for carbon monoxide; FEV 1, forced expiratory volume in the first second; MVV, maximal voluntary ventilation; O 2 pulse, oxygen pulse; SaO 2, arterial hemoglobin oxygen saturation; VE, maximal minute ventilation; VO 2max, maximal oxygen consumption. 의흡연력이있었다 ( 표 2). 이들의평균일반폐기능검사는 1 초간노력성호기량 (FEV1) 은 58.3±17.4% 로분류상 Grade II 에속하였으며, 운동부하심폐기능검사상으로도 VO 2max는 17.6±6.04 ml/kg/min 으로 Grade II에속하였다 ( 표 3). 그외평균 MVV는 51.0±16.8 L/min, VO 2max (% pred.) 는 68.4± 22.8%, maximal minute ventilation은 38.1±14.1 L/min, Breathing reserve는 12.9±14.8 L/min였다 ( 표 3). 각각의장애등급으로나누어진환자들에대해서각각중증도별비교에서는 GOLD 진료지침에따른분류상 Grade I 으로판정된환자수는 16명이었고, Grade II는 54명, Grade III은 31명, Grade IV는 4명이었다 ( 표 4). ATS 진료지침에따른분류상 Grade I로판정된환자수는 16명이었고, Grade II 는 33명, Grade III은 35명, Grade IV는 21명이었다 ( 표 5). 운

4 - 대한내과학회지 : 제 76 권제 5 호통권제 585 호 Table 4. Degree of impairment by pulmonary function test and cardiopulmonary exercise testing according to GOLD guideline Severity by PFT Severity by CPET Grade I Grade II Grade III Grade IV Total Grade I Grade II Grade III Grade IV total CPET, cardiopulmonary exercise test; GOLD, Global initiative for Chronic Obstructive Lung Disease PFT, pulmonary function test. Table 5. Degree of impairment by pulmonary function test and cardiopulmonary exercise testing according to ATS guideline Severity by PFT Severity by CPET Grade I Grade II Grade III Grade IV Total Grade I Grade II Grade III Grade IV total ATS, American Thoracic Society; CPET, cardiopulmonary exercise test; PFT, pulmonary function test. Table 6. Cardiopulmonary data for patients classified as more and less severe on cardiopulmonary exercise test than pulmonary function test Variable Less severe (Mean±SD) More severe (Mean±SD) p-value VE (L) 50.7± ± 9.70 <0.001 HRmax (%) 86.5± ± VO 2_AT (% VO 2max) 89.6± ± 23.3 <0.001 O 2 pulse (% pred) 103.8± ±18.5 <0.001 FEV 1 (% pred) 51.7± ± VO 2max (% pred) 91.2± ±15.5 <0.001 AT appearance (n, %) 15 (72.3%) 18 (35.2%) <0.001 BR (L/min) 0.40± ±16.4 < BMI, body mass index; BR, breathing reserve; FEV 1, forced expiratory volume in the first second; HRmax, maximal heart rate; O 2 pulse; oxygen pulse; VE, maximal minute ventilation; VO 2_AT, oxygen consumption at anaerobic threshold; VO 2max, maximal oxygen consumption. 동부하심폐기능검사상의중증도분류에서는 Grade I 환자수는 23명, Grade II는 34명, Grade III은 25명, Grade IV는 23 명이었다 ( 표 4, 5). GOLD 진료지침과 ATS 진료지침에의해분류된환자를비교하면 1초간노력성호기량이예측치의 60~50% 사이의환자 21명이 ATS 분류상은 Grade III로 GOLD 분류상은 Grade II로분류되었으며, 또한 40~30% 사이의환자 17명이 ATS 분류상은 Grade IV로 GOLD 분류상은 Grade III에포함되었다. GOLD 분류상중간의중증도 (II, III) 로분류된그룹은일반폐기능검사에서는 85명이었고, 운동부하심폐기능검사에서는 59명이었다. Grade IV로평가된환자수는일반폐기능검사상 4명이었지만, 운동부하심폐기능검사상에서는 23명으로큰차이를보였다 ( 표 4). 일반폐기능검사와운동부하심폐기능검사결과상, 두가지검사에따른분류의일치율은 42% 였다. 불일치를보이는경우는 GOLD 진료지침기준상분류에서 105명중에서 61명으로전체의 58% 였으며, 이러한불일치한결과중일반폐기

5 - 나운태외 6 인. COPD 의폐기능검사와 CPET 비교 - 능검사보다운동부하심폐기능검사에서좀더경한판정을받은사람은 21명 (20%) 이었고, 반대로더심한판정을받은사람은 40명 (38%) 이었다. ATS 진료지침을따른경우도 105 명중 46명이두검사상불일치를보였으며이는전체의 43.8% 에해당하였다 ( 표 5). 일반폐기능검사와운동부하심폐기능검사상중증도가불일치한환자들에서각각의운동부하심폐기능검사항목을비교한결과, 분당환기량, 혐기성역치의발생률, 혐기성역치도달시기, 최대산소섭취량, oxygen pulse, 호흡예비능에서두군간에통계적으로유의한차이를보였다 ( 표 6). 그러나최대심박동수는두군간에서큰차이를보이지않았다. 혐기성역치가나타난경우에는역치도달이일찍일어날수록, oxygen pulse가작을수록, 호흡예비능가많을수록더심한판정을받았다. 경한판정을받은군에서의혐기성역치발현율은 72.3% 인데반하여운동부하검사상심한판정을받은군은 35.2% 에서발현되었다 ( 표 6). 또한더심한판정을받은군에서는혐기성역치가나타나는경우가훨씬적었다 ( 표 6). 고찰 COPD은현재세계인구의사망원인들중네번째로흔하며, 점차그빈도가증가하고있는질환이다 1,2). 이러한 COPD 질환의중요성을인식시키고이를효과적으로진단, 치료및관리하기위해서 US National Heart, Lung, and Blood Institute (NHLBI) 와세계보건기구 (World Health Organization) 가 COPD 의관리지침을설정한것이 Global Initiative for Chronic Obstructive Lung Disease (GOLD) 이다 1,2). 그러나 GOLD guideline에서기준이되는일반폐기능검사만으로는환자가실생활에서겪는장애 (disability) 정도와운동내성 (exercise capacity) 의한계를예측하는데는어려움이있다 3-5). COPD 환자들은안정시보다는주로활동시호흡곤란과일상생활의제약을호소하고, 호흡곤란과함께환기능감소에의한운동능력의저하를보이는것이특징이어서, 이를안정시의일반폐기능검사만으로는평가하는데는한계가있다. 그러므로 COPD 환자를평가하는데있어서운동시환자상태평가가중요하며, 나아가안정시일반폐기능검사치와운동시폐기능검사간의상호연관성과차이에대한이해가필요하다. 운동부하심폐기능검사는 COPD 환자의예후를예측할수있다는여러전향적연구가보고된이래, COPD 환자에서운동부하심폐기능검사를이용하여예후에대한평가자료로 사용하는경우가많아지고있다 13). COPD 에서는매우다양한운동역량을보이며이는기도폐쇄정도와항상비례하지는않는다는것은잘알려진사실이다 14,15). 본연구는 COPD 환자에서일반폐기능검사와운동부하심폐기능검사를시행하고, 그결과를 ATS 진료지침과 GOLD 진료지침을참고하여 COPD를중증도별로분류하여두가지검사결과를비교하였다. 검사결과상두가지검사에따른분류에있어서일치율은 42% 밖에되지않았다. 불일치를보이는경우가 GOLD 진료지침기준상분류에서 105명중에서 61명으로전체의 58% 에해당하였으며, 이러한불일치한결과중일반폐기능검사보다운동부하심폐기능검사에서좀더경한판정을받은사람은 21(20%) 명이었고, 반대로더심한판정을받은사람은 40(38%) 명이었다. ATS 진료지침을따른경우도 105명중 46명이두검사상불일치를보였으며이는전체의 43.8% 에해당하였다 ( 표 5). 즉, 두분류모두안정시폐기능검사와운동부하심폐기능검사상높은불일치율을보였다. 이는안정시폐기능검사로환자의운동능력을예측하는데는한계가있음을보여주는결과이다. 안정시에시행하는일반폐기능검사만으로환자의운동역량을예상하는것은어려우며, 같은 1초간노력성호기량값을보인환자라도운동역량은심한차이를보일수있는데, 이는병태생리가개인마다차이가있고, 운동하는동안에이루어지는호흡생리또한각개인마다차이가있기때문이다 4). 이러한이유또한일반폐기능검사뿐만아니라운동부하심폐기능검사가호흡능력손상정도를평가하는데유용할수있다. 폐기능검사결과와운동부하심폐기능검사결과가단지 42% 에서만일치하고있고나머지 58% 는더심하거나, 더경한판정을운동부하심폐기능검사에서받았다. 그리고운동부하심폐기능검사는안정시폐기능검사에비해서중간영역 ( 중등도, 중증 ) 에속하는환자의비율이상대적으로낮은경향을보였으며 (81% vs. 56%), 좀더고른분포를보였다. 향후이러한차이가예후예측에어떠한영향을미치는지관찰이필요하겠다. GOLD 진료지침과 ATS 진료지침에의해분류된환자를비교하면 1초간노력성호기량이예측치의 60~50% 사이의환자 21명이 GOLD 진료지침에서는 Grade II로, ATS 진료지침에서는 Grade III으로분류되고, 또한 40~30% 사이의환자 17명이 ATS 분류상은 Grade IV로 GOLD 분류상은 Grade III 으로포함된차이를나타냈다. 이러한차이가 ATS 진료지침에따른분류가 GOLD 진료지침에따른분류에비해서운동

6 - The Korean Journal of Medicine: Vol. 76, No. 5, 부하심폐기능검사와의일치율을높여주었다 (42% vs. 56.2%). COPD 환자에서운동부하심폐기능검사중에운동중단원인으로호흡기계의요인뿐아니라, 심혈관계의기능제한도주된운동제한요소로작용할수있다 16). 본연구에서도운동부하검사분류상더심한판정을받은환자들은분당환기량, 혐기성역치시의산소섭취량, 최대산소섭취량, oxygen pulse, 호흡예비능에있어서그반대의경우의그룹에비해통계적으로유의한차이를보여주었다 ( 표 5). 이들은 1초간노력성호기량은오히려많은반면에 oxygen pulse는작았고, 호흡예비능은매우많이남아있는경향을보였다 ( 표 5). 물론최대심박동수에있어서는커다란차이는없었지만, 이러한결과로미루어보아이들은심혈관계의기능제한이주된운동중단의원인으로작용하였음을판단할수있고, 더나아가심혈관계의기능이좀더감소되어있음을추정할수있다. 그러므로운동부하심폐기능검사에서더심한판정을받는환자들에대해서는심혈관계병력이없을지라도, 심혈관계기능을평가해보고, 심혈관계위험인자에대해점검해보는것이바람직할것으로생각된다. 이러한결과들로미루어운동부하심폐기능검사는일반폐기능검사와더불어환자의호흡기능의장애와함께전신상태를평가함에있어추가적인유용한정보를제공하며, 더나아가환자의임상경과및예후와의연관성에대한연구도필요하리라생각된다. 특히두가지검사상에서운동부하심폐기능검사결과가일반폐기능검사보다더심한결과를보이는경우에는심혈관계질환에대한추가적평가를시행해보는것이바람직하리라고생각되며, 이에대한추가적인연구가필요하리라생각된다. 요약목적 : 일반폐기능검사만으로는 COPD 환자가실생활에서겪는장애정도와운동내성의한계를예측하는데는한계가있어, 일반폐기능검사와운동부하심폐기능검사를이용하여 COPD 환자를중증도별로하여각각분류하고그결과를비교하여, 운동부하폐기능검사의유용성을알아보고자하였다. 방법 : COPD 환자 105명을대상으로안정시폐기능검사와운동부하심폐기능검사를시행하였고, 결과는표준의학중증도분류에의해 categorical statistical comparison으로분석하였다. 결과 : 두검사에서 COPD 환자 105명중오직 44명 (42%) 의환자가일치된결과를보였다. 나머지환자들중 21명 (20%) 은일반폐기능검사보다운동부하심폐기능검사에서경한판정을받았고, 40명 (38%) 은운동부하심폐기능검사에서더심한판정을받았다. 운동부하심폐기능검사에서더심한판정을받은환자들은운동부하검사심혈관계지표들이보다감소되어있었다. 결론 : COPD 환자의운동능력은일반폐기능검사만으로는예측하는데는한계가있으며, 전신질환으로서의 COPD 질환을이해하고예측하는데있어운동부하폐기능검사도일부도움을주리라생각되나, 앞으로좀더많은연구가필요하리라사료된다. 중심단어 : 만성폐쇄성폐질환 ; 운동검사 ; 폐기능검사 REFERENCES 1) National Institutes of Health, National Heart, Lung and Blood Institute. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. NHLBI/WHO Workshop Report. Publication number 2701, ) National Institutes of Health, National Heart, Lung and Blood Institute. Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. NHLBI/WHO Workshop Report. Update 2007 GOLD guideline. 3) Fink G, Moshe S, Goshen J, Klainman E, Lebzelter J, Spitzer S, Kramer MR. Functional evaluation in patients with chronic obstructive pulmonary disease: pulmonary function test versus cardiopulmonary exercise test. J Occup Environ Med 44:54-58, ) Pineda H, Haas F, Axen K, Hass A. Accuracy of pulmonary function tests in predicting exercise tolerance in chronic obstructive pulmonary disease. Chest 86: , ) Mahler DA, Harver A. Prediction of peak oxygen consumption in obstructive airway disease. Med Sci Sports Exerc 20: , ) American Thoracic Society, American College of Chest Physicians. ATS/ACCP statement on cardiopulmonary exercise testing. Am J Respir Crit Care Med 167: , ) Wasserman K, Hanes JE, Sue DY, Whipp BJ. Principles of exercise determination and interpretation. Philadelphia, Lea and Febriger, ) Cotes JE, Zejda J, King B. Lung function impairment as a guide to exercise limitation in work-related lung disorders. Am Rev Respir Dis 137: , ) Ries AL, Farrow JT, Clausen JL. Pulmonary function tests cannot predict exercise-induced hypoxemia in chronic obstructive pulmonary disease. Chest 93: , ) Karlman W, James EH, Darryl YS, Brian JW. Principles of exercise test and interpretation. Philadelphia, Lea and Febgier,

7 - Woon-Tae Na, et al. Comparison of spirometry with CPET of COPD - 11) Beaver WL, Wasserman K, Whipp BJ. A new method for detecting the anaerobic threshold by gas exchange. J Appl Physiol 60: , ) American Thoracic Society. Evaluation of impairment/disability secondary to respiratory disorder. Am Rev Respir Dis 133: , ) Tojo N, Ichioka M, Chida M, Miyazato I, Yoshizawa Y, Miyasaka N. Pulmonary exercise testing predicts prognosis in patients with chronic obstructive pulmonary disease. Intern Med 44:20-25, ) Killian KH, Campbell EJ, Summers E, Jones NL. Relationship between pulmonary impairment, exercise capacity and intensity of dyspnea. Eur Respir J 6(Suppl 17):571S, ) Cotes J, Posner V, Reed JW. Estimation of maximal exercise ventilation and oxygen uptakes in patients with chronic lung disease. Bull Eur Physiopathol Respir 18(Suppl 4): , ) Oren A, Sue DY, Hansen JE, Torrance DJ, Wasserman K. The role of exercise testing in impairment evaluation. Am Rev Respir Dis 135: ,

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012임수진 Received : 2012. 11. 27 Reviewed : 2012. 12. 10 Accepted : 2012. 12. 12 A Clinical Study on Effect of Electro-acupuncture Treatment for Low Back Pain and Radicular Pain in Patients Diagnosed with Lumbar