The Medico-Legal and Ethical Problems of Withholding / Withdrawing of Futile Life-Sustaining Mechanical Respirator treatment / 결핵및호흡기질환

The first and the longest criminal indictment case of Korean medico-legal battle, so called BORAMAE Hospital Incident, was finally on its end by Korean Supreme Court's decision on June 24, 2004, after 7 years long legal dispute via Seoul District Court and Seoul Superior Appeal Court's decision. Boramae Hospital case was the first Korean legal case of Withdrawing Life-sustaining treatment of mechanical respirator on 58 years old Extradural Hematoma victim who was on Respirator under Coma after multi-organ failure postoperatively(APACHE II score: 34-39). Two physicians who have involved patient's care and had helped to make discharge the Near-death patient to home after repeated demand of patient's wife, due to economic reason, were sentenced as homicidal crime. This review article will discuss the following items with the review of US cases, Quinlan(1976), Nancy Cruzan(1990), Barber (1983), Helen Wanglie(1990), Baby K (1994) and Baby L cases, along with Official Statement of ATS and other Academic dignitaries of US and World.: [1] Details of Boramae Hospital incident, medical facts description and legal language of homicidal crime sentence. [2] The medical dispute about the legal misinterpretation of patient's clinical status, regarding the severity of the victim with multi-organs failure on Respirator under coma with least chance of recovery, less than 10% probability. [3] Case study of US, of similar situation. [4] Introduction of ATS official Statement on Withdrawing/ Withholding Life sustaining treatment. [5] Patient Autonomy as basic principle. [6] The procedural formality in Medical practise for keeping the legitimacy. [7] The definition of Medical Futility and its dispute. [8] Dying in Dignity and PAS(Physician Assisted Suicide)/and/or Euthanasia [9] The Korean version of "Dying in Dignity", based on the Supreme Court's decision of Boramae Hospital incident (2004.6.24.) [10] Summary and Author's Note for future prospects.

Chronic Necrotizing Bronchopulmonary Aspergillosis With Elements of Bronchocentric Granulomatosis

Chronic necrotizing pulmonary aspergillosis (CNPA) is an unusual form of pulmonary aspergillosis arising in the setting of mildly immune compromised state or altered local defense system. CNPA rarely shows histological findings mimicking bronchocentric granulomatosis (BCG), which is characterized by peribronchiolar granulomatous destruction. We describe a case representing CNPA with elements of BCG. A-64 year-old woman was admitted because of atypical pneumonia with multi-focal variable sized consolidations and cavitary lesions on high-resolution computed tomography (HRCT). The open lung biopsy specimen showed large areas of necrotizing pneumonia with some scattered aspergillus hyphae within the lung parenchyma. Some terminal bronchioles were found to be destroyed and were replaced by peribronchiolar granulomatous inflammation. There was no evidence of angioinvasion by aspergillus or aspergillous emboli. Despite vigorous antifungal agent and steroid treatment, she died of acute airway obstruction by bronchial casts on the thirty-fourth hospital day.

The Correlation between HRCT Emphysema Score and Exercise Pulmonary Testing Parameters / 결핵

BACKGROUND: The correlation between the high resolution computed tomography(HRCT) emphysema score and the physiologic parameters including resting and exercise pulmonary function test was investingated in 14 patients(60.6±10.3 years) with pulmonary emphysema. METHODS: The patients underwent a HRCT, a resting pulmonary function test, and incremental exercise testing(cycle ergometer, 10 W/min). Computed tomography scans were obtained on a GE highlight at 10 mm intervals using 10 mm collimation, from the apex to the base after a full inspiration. The emphysema scores wer determined by a CT program 'Density mask' outlining the areas with attenuation values less than -900 HU, indicating the emphysema areas, and providing an overall percentage of lung involvement by emphysema. RESULTS: Among the resing PFT parameters, only the diffusing capacity(r=-0.75) and PaO2 (r=-0.66) correlated with the emphysema score(p<0.05). Among the exercise test parameers, the emphysema score correlated significantly with the maximum power(r=-0.74), maximum oxygen consumption(r=-0.68), anaerobic threshold(V-slope method : r=-0.69), maximal O2-pulse(r=-0.73), and the physiologic dead space ratio at the maximum workload(r=-0.80)(p<0.01). CONCLUSION: We could find that exercise testing parameters showed a much better correlation with the HRCT emphysema score, which is known to have a good correlation with the pathologic severity than the resting PFT parameters. Therefore it is suggested that exercise testing is superior to resting PFT for estimating in the estimation of the physiologic disturbance in emphysema patients.

A Case of Mediastinal Angiomyolipoma

Angiomyolipoma is a common tumor of the kidney but has rarely been found in the mediastinum. We report a case of angiomyolipoma of the posterior mediastinum in a 62-year-old woman. She experienced exertional dyspnea and intermittent cough at admission. Computed tomography indicated a tumor located at the left paravertebral and upper posterior mediastinum and MRI imaging demonstrated a mass with low signal intensity in T1-weighted image at T4-5 level. Thoracotomy was done for surgical removal of the tumor and histologic examination revealed a mesenchymal tumor composed of mature fat, capillaries and smooth muscle fibers. The tumor was immunohistochemically positive for CD34 and factor-VIII (for vascular component) smooth muscle actin (for smooth muscle component) and S-100 protein (for fat component). There have been four case reports about mediastinal angiomyolipoma, namely three Japanese cases and one French case. It is suggested that angiomyolipoma could be considered for the differential diagnosis of mediastinal tumors.

A Case of Mediastinal Pancreatic Pseudocyst / 결핵

A pancreatic pseudocyst with a mediastinal extension is a rare clinical entity. Intrathoracic symptoms such as dysphagia or dyspnea due to compression or associated pleural effusions are quite common. The pseudocysts transverse the diaphragm via the esophageal hiatus or aortic hiatus or by eroding directly through the diaphragm. Here, we report a case of a pancreatic pseudocyst with a mediastinal extension presenting as dysphagia and dyspnea. The diagnosis was confirmed by computerized axial tomography of the chest and abdomen. Usually, the proper management of a larger pseducocyst includes percutaneous or surgical internal drainage, but in this case the mediastinal components disappeared with conservative medical treatment.

NF-κB Dependent IL-8 Secretion from Lung Epithelial Cells Induced by Peripheral Blood Monocytes Phagocytosing Mycobacterium Tuberculosis / 결핵

BACKGROUND: IL-8 is a potent chemotactic cytokine that plays an important role in the host defense mechanism against M. tuberculosis by recruiting inflammatory cells to the site of the infection. Lung epithelial cells, as well as alveolar macrophages are known to preduce IL-8 in response to M. tuberculosis. IL-8 gene expression is mainly regulated on the level of transcription by NF-κB. This study investigated whether or not A549 cells produce IL-8 in NF-κB dependent mechanism in response to macrophages phagocytosing M. tubersulosis. METHODS: Peripheral blood monocytes that were obtained from healthy donors were cultured for 24 h with M. tuberculosis and a conditioned medium(CoMTB) was obtained. As a negative control, the conditioned medium without M. tuberculosis (CoMCont) was used. A549 cells were stimulated with M. tuberculosis, CoMCont and CoMTB and the IL-8 concentration in the culture media was measured by ELISA. The CoMTB induced IL-8 mRNA expression in the A549 cells was evaluated using RT-PCR, and CoMTB induced IκBα degradation was measured using western blot analysis. CoMTB induced nuclear translocation and DNA binding of NF-κB was also examined using an electrophoretic mobility shift assay(EMSA), and the CoMTB induced NF-κB dependent IL-8 transcriptional activity was measured using a luciferase reporter gene assay. RESULTS: CoMTB induced IL-8 production by A549 cells(46.8±4.8 ng/ml) was higher than with direct stimulation with M. tuberculosis (6.8±2.9 ng/ml). CoMTB induced IL-8 mRNA expression increased after 2 h of stimulation and was sustained for 24 h. IκBα was degraded after 10 min of CoMTB stimulation and reappeared by 60 min. CoMTB stimulated the nuclear translocation and DNA binding of NF-κB. The CoMTB induced NF-κB dependent IL-8 transcriptional activity(13.6±4.3 times control) was higher than either CoMCont(2.0±0.6 times control) or M. tuberculosis (1.4±0.6 times control). CONCLUSION: A conditioned medium of peripheral blood monocytes phagocytosing M. tuberculosis stimulates NF-κB dependent IL-8 production by the lung epithelial cells.

The Immunohistochemical analysis for the expression of survivin, an inhibitor of apoptosis protein, in non-small cell lung cancer / 결핵

BACKGROUND: Defects in apoptotic signaling pathways play important role in tumor initiation, progression, metastasis and resistance to treatment. Several proteins which may promote tumorigenesis by inhibiting apoptosis were identified. The survivin protein is the member of inhibitor of apoptosis protein(IAPs) family which inhibits apoptosis. Unlike other IAPs, it is expressed in during the fetal period but not in adult differentiated tissues. Many reports have stated that survivin is selectively expressed in many cancer cell lines and cancer tissues. We performed immunohistochemical analysis for survivin expression in non-small cell lung cancer to get evaluate its clinical implication. METHODS: Twenty nine surgically resected lung cancers were examined. Immunohistochemical staining were performed by immuno-peroxidase technique using avidin-biotinylated horseradish peroxidase complex in the formalin-fixed, paraffin-embedded tissue 4 µm section. Anti-survivin polyclonal antibody was used for primary antibody and anti-p53 monoclonal antibody was also used to analyze the correlation between survivin and p53 expression. The survivin expression scores were determined by as the sum of the stained area and intensity. RESULTS: Immunohistochemical analysis showed cancer specific expression of survivin in 20 of 29 cases (69.0%). Western blot analysis also showed the selective survivin expression in turmor tissue. There was no correlation between survivin expression and clinicopathological parameters and prognosis. We analyzed the correlated between survivin expression and p53 expression, but found none. CONCLUSION: We confirmed the tumor specific expression of survivin in non-small cell lung cancer But this pression was not correlated with clinical parameters as well as histlogy, tumor stage recurrence, and sur rate. Also it ws not statistically correlated with the expression of p53.

Inhibitory mechanism on NF-kB transactivation by dexamethasone in pulmonary epithelial cells / 결핵

Glucocorticoid receptor (GR) functions as a suppressor of inflammation by inhibiting the expression of many cytokine gene activated by NF-κB. The goal of this study is to investigate the mechanism by which GR repress NF-κB activation in lung epithelial cells. We used A549 and BEAS-2B lung epithelial cell lines. Using IgGκ-NF-κB luciferase reporter gene construct, we found that dexamethasone significantly suppressed TNF-α-induced NF-κB activation and the overexpression of GR showed dose-dependent reduction of TNF-α-induced NF-κB activity in both cell lines. However, DNA binding of NF-κB induced by TNF-α in electromobility shift assay was not inhibited by dexamethasone. Super shift assay with anti-p65 antibody demonstrated the existence of p65 in NF-κB complex induced by TNF-α Western blot showed that IκBα degradation induced by TNF-α was not affected by dexamethasone and IκBκ was not induced by dexamethasone, neither. To evaluate p65 specific transactivation, we adopted co-transfection study of Ga14-p65TA1 or TA2 fusion protein expression system together with 5xGa14-luciferase vector. Co-transfection of GR with Ga14-p65TA1 or TA2 repressed luciferase activity profoundly to the level of 10-20% of p65TA1- or TA2-induced transcriptional activity. And this transrepressional effect was abolished by co-transfection of CBP or SRC-1 expression vectors. These results suggest that Gr-mediated transrepression of NF-κB in lung epithelial cells is through competing for binding to limiting amount of transcriptional coactivators, CBP or SRC-1.

Cervical tuberculous lymphadenitis : Clinicopathological reatures and AFB positivity / 결핵

BACKGROUND: Histological analysis of tuberculosis shows a spectrum of findings, from well formed granulmatous inflammation with few bacilli in patient with normal immune response to M. tuberculosis to poorly formed granulomatous inflammation with many bacilli in patient with defective immune response. To evaluate the degree of immune response to M. tuberculosis, we studied the histologic features, including the presence of acid fast bacilli(AFB) in lymph node of patients with cervical tuberculous lymphadenitis, and compared them with clinical characteristics. METHODS: We reviewed the histologic features of 33 cases of cervical tuberculous lymphadenitis and processed the excised nodes for auramine-rhodamine staining to detect AFB. The AFB positivity in tissue was compared with the histologic features(degree of granuloma formation, presence of caseation necrosis, presence of neutrophilic infiltration) and clinical characteristics (lymph node size, duration of symptom, presence of local symptom or radiologic evidence of pulmonary tuberculosis). RESULTS: 1) The mean age at diagnosis was 42.4 years, and male to female ratio was 1 : 45. 2) Histologically, all cases showed well formed granuloma and variable degrees of caseation necrosis, and 39% of the cases showed neutrophilic infiltration in the granulomatous inflammation. 3) AFB were confirmed in 52% of the cases, and they were found extracellularly and at the periphery of caseation necrosis. 4) There was no association between AFB Positivity and histological features or clinical characteristics. CONCLUSION: Cervical tuberculous lymphadenitis showed well formed granulomatous inflammation with caseation necrosis, and there was no association between AFB positivity in the tissue and histological or clinical characteristics.

A case of hypersensitivity pneumonitis with positive precipitin antibody to Trichosporon cutaneum / 천식및알레르기

A 25-year-old woman complaining of dyspnea on exertion, coughing, fever and chills was admitted in January, 1998. Her clinical, radiological, and pathological findings were compatible with hypersensitivity pneumonitis and precipitin antibody to Trichosporon cutaneum was detected in her serum. Although some cases of T. cutaneum-induced hypersensitivity pneumonitis developed during the winter season were reported in Japan, there had been no report of such a case in Korea. This case suggests that T. cutaneum-induced hypersensitivity pneumonitis can develop beyond the summer season in certain environments.

A case of Tetranychus urticae - induced asthma in an inhabitant around pear orchard / 천식및알레르기

There have been a few reports of occupational asthma caused by Tetranychus urticae in fruit farmers or greenhouse workers. We report a case of bronchial asthma induced by Tetranychus urticae from a pear orchard in Cheonan city. An 18-year-old female student living around a pear orchard suffered from intermittent cough, rhinorrhea, and dyspnea for the 3 years. Her PC20 -methacholine was 0.15mg/ml, and skin prick test done with 55 inhalant allergens showed negative responses except Tetranychus urticae extract which was prepared with highly parasitized pear leaves. Bronchial provocation test with Tetranychus urticae extract showed a dual asthmatic response. These findings indicate that Tetranychus urticae, which include parasites in fruit trees, herba,ceous plants, and greenhouse cultures, can cause IgE-mediated bronchoconstriction in Korea.

A case of tuberculous pericarditis presenting as pericardial mass compressing pulmonary artery / 대한내과학회지

Tuberculous pericarditis is a rare form of tuberculosis usually presenting as pericardial effusion or constrictive pericarditis. But rarely it may present as pericardial mass. We experienced a case of tuberculous pericarditis presenting as pericardial mass which was confirmed by open thoracotomy. The patient was 34-year-old female, who was previously treated for tuberculous pleurisy. She admitted for dyspnea on exertion and imaging study including chest CT and echocardiography showed pericardial mass. Open thoracotomy showed hard adhesive mass lesion around pulmonary artery and pathology showed chronic granulomatous inflammation with caseation necrosis. We report a rare case of tuberculous pericarditis presenting as pericardial mass.

A case of tuberculous pericarditis presenting as pericardial mass compressing pulmonary artery / 대한내과학회지

Tuberculous pericarditis is a rare form of tuberculosis usually presenting as pericardial effusion or constrictive pericarditis. But rarely it may present as pericardial mass. We experienced a case of tuberculous pericarditis presenting as pericardial mass which was confirmed by open thoracotomy. The patient was 34-year-old female, who was previously treated for tuberculous pleurisy. She admitted for dyspnea on exertion and imaging study including chest CT and echocardiography showed pericardial mass. Open thoracotomy showed hard adhesive mass lesion around pulmonary artery and pathology showed chronic granulomatous inflammation with caseation necrosis. We report a rare case of tuberculous pericarditis presenting as pericardial mass.

A Case of allergic angitis and granulomatosis with manifestation of pleuritis and pericarditis / 천식및알레르기

Allergic angitis and granulomatosis is a kind of rare systemic vasculitis, with various manifestations of disease of lung, heart, skin, musculoskeletal system, nervous system and hepatobiliary tract. There was no report of a case with manifestation of pleuritis and pericarditis, while several cases had been reported in Korea. So we here report a case of allergic angitis and granulomatosis with manifestations of pleuritis and pericarditis. The case also showed clinical manifestations of hypereosinophilia, asthma, rhinitis, pulmonary infilterates with eosinophilia and nephritis. Open lung biopsy showed arteritis with heavy infilteration of activated eosinophil in lung, pleura and pericardium. The involvement of heart might cause critical complication leading death. The patients who are supposed as allergic angitis and granulomatosis should be examined for the involvement of heart.

A Case of Visceral Botryomycosis Accompanied by Early Lung Cancer / 대한내과학회지

Botryomycosis is a rare, chronic and suppurative di- sease that is often mistaken clinically and histologically for a fungal infection, because the histologic feature shows a cluster of bacteria found within an eosinophilic matrix or capsule, giving the appearance of granules mimicking the sulfur granules of actinomycosis. Staphy- lococcus aureus is the most common organism cultured from lesions of botryomycosis, but other bacteria have also been isolated and implicated, including Psudomonas aeruginosa, E. coli, Proteus spp., Bacillus spp.. In some case, multiple pathogenic bacteria were found on cul ture. This disease has two patterns of organ involve ment. The more common type is cutaneous type, which involves the skin, subcutaneous soft tissue, muscle and bone. The other is visceral type which involves the lungs, liver, tongue, orbit, bowel, brain, kidney or pros tate. We report a case of brain and pulmonary botry omycosis in a 60 year-old man, who have early lung cancer. Botryomycosis was diagnosed by brain mass removal, PCNA and bronchoscopy, and lung cancer was detected incidentally by bronchoscope. The patient was treated with the Penicillin G after operation of brain mass, and right pneumonectomy was done.

Effect of Exercise on Pulmonary Function / 결핵

BACKGROUND: The effects of exercise on pulmonary function are complex and have been the subject of many investigations. But, there has been disputes about the effect of exercise on spirometric parameters and there is no study about the effect of exercise on IOS(Impulse Oscillometry)parameters. lOS, a new method of pulmonary funtion test, is based on the relationship between the pressure and flow oscillation which is produced by applying sinusoidal pressure oscillation to the respiratory system via the mouth. METHOD: Fifty-nine young adults without respiratory symptoms were divided into three groups according to degree of exercise(hard exercise group: mean exercise time is over three hours per week at least for the last one month, light exercise group: between thirty minutes to three hours, nonexercise group : less than thirty minutes) and undertaken pulmonary function test(simple spirometry and IOS). RESULTS: The effects of exercise on spirometric parameters ; percentage of predictive value of forced vital capacity(FVC % pred) was higher in hard exercise group than nonexercise group(hard exercise group:102.4+/-14.8, nonexercise group: 93.7+/-9.9, p= 0.017), but there was no significant diffetence in percentage of predicted value of forced expiratory volume in one second(FEV 1% prod) and percentage of predicted value of forced expiratory flow 50% (FEF 50% pred) between groups. The effects of exercise on LOS parameters : Reactance at 5Hz(X5) was significantly lower in hard exercise group than nonexercise group(hard exercise group: -0.166+/-0.123hPa/1/s, nonexercise group: 0.093+/-0.036hPa/1/s, p= 0.006) but there was no significant difference in central resistance(Rc), peripheral resistance(Rp), resonance frequency(RF) and resistance at 5Hz, 20Hz between groups. CONCLUSION: Hard exercise increased FVC % pred on spirometric parameters and decreased reactance at 5Hz (X5) on lOS parameters.

Common Cold

No abstract available.

Diagnostic Value of Adenosine Deaminase(ADA) and its Isoenzyme in Pleural Effusion / 결핵

BACKGROUND: Etiologic diagnosis of pleural effusion is usually made by clinical characteristics, pleural fluid analysis and pleural biopsy. But, despite careful diagnostic study, the cause of pleural effusion cannot be found in about 20 percent of patients, especially in loculated pleural effusions. Tuberculous pleurisy is one of the most common cause of pleural effusion in Korea. But, pleural fluid culture for Mycobacterium tuberculosis are positive in only 20 to 30 percent of patients and typical pleural biopsy finding in less than 50 percent of patients with this disease. In recent studies, adenosine deaminse(ADA) and its isoenzymes were proposed to be a useful diagnostic tool for differential diagnosis of pleural effusion We investigated the pattern of ADA and its isoenzyme activities in various cause of pleural effusions to evaluate the diagnostic value of measuring ADA and its isoenzymes. METHOD: We measured total ADA and its isoenzyme activities in pleural fluid and serum from 54 patients with pleural effusion(25 tuberculous pleural effusion, 10 parapneumonic effusion, 14 malignant pleural effusion, 5 transudative pleural effusion), including 5 loculated tuberculous pleural effusions and 6 loculated parapneumonic effusions. Total ADA activity was measured by the spectrophotometric method and ADA2 isoenzyme activity was measured with same method using EHNA, potent inhibitor of ADA1 isoenzyme activity. RESULT: Total ADA activity of tuberculous pleural effusion was higher than malignant pleural effusion(p<0.01), but no significant difference was found between tuberculous pleural effusion and parapneumonic effusion (tuberculous pleural effusion:148.9+/-9.91U/L, parapneumonic effusion:129.0+/-119.41U/L, malignant pleural effusion 48.7+/-9.71U/L). Percentage of ADA2 activity to total ADA activity(ADA2%) of pleural effusion of tuberculous pleurisy was higher than parapneumonic effusion(p<0.05), but no significant difference was found between tuberculous pleural effusion and malignant pleural effusion(tuberculous pleural effusion: 57.2+/-10.7%, parapneumonic effusion: 35.9+/-17.8%, malignant pleural effusion: 60.7+/-4.1%). In loculated pleural effusion, ADA2% of tuberculous pleural effusion was higher than parapneumoriic effusion(tuberculous pleural effusion: 53.3+/-3.9%, parapneumonic effusion: 27.8+/-7.9%). CONCLUSION: Measurement of ADA isoenzyme activity is useful for differentiating tuberculous pleural effusion from parapneumonic effusion, especially in loculated pleural effusion.

The Application of Impulse Oscillometry(IOS) in the Detection of Smoking Induced Early Airway Obstruction / 결핵

BACKGROUND: Impulse Oscillometry is a noninvasive and effort-independent test used to characterize the mechanical impedance of the respiratory system. The clinical potential of the 105 is rapid and demands only passive cooperation which makes it especially appealing for children, for epidemiologic surveys and for conditions in which quiet breathig instead of forced expiratory maneuvers are preferred. However, several studies have shown conflicting results that the role of 108 about detection of smoking induced small airway diseases or early airway obstruction METHODS: Study was to evaluate the clinical ability of the 108 to detect about smoking induced early airway obstruction in persons with normal spirometry test. Respiratory asymptomatic study groups were formed that one is non-smoking group, another is smoking group. RESULTS: The parameters of spirometry were not significantly differences between non-smoking group and smoking group. Among the parameters of 108, total resistance(non-smoking group: smoking group= 2.22 +/-1.20 : 2.58 +/-1.71), peripheral resistance( 1.25 +/-0.62 : 1.47 +/-0.10), bronchial compliance(0.44 +/-0.12: 0.47 +/-0.16) were not statistically significant different (p<0.05), but central resistance and lung compliance were not statistically significant different (unit ; resistance= hPa/l/s, compliance= 1/hPa). Resistance(Rrs) was not statistically significant different with changes of frequences(5, 10, 15, 20, 25, 30, 35Hz), but Reactance(Xrs) was statistically significant differenct with low frequences that X5(non-smoking group : smoking group= -0.62 +/-0.28 : - 0.76 +/-0.48, p<0.001) and X10(-0.06 +/-0.19 : -0.15 +/-0.33, p<0.013) (unit; hPa/l/s, hPa=cmH2O) CONCLUSION: Impulse oscillometer(IOS) is clinically available method to detect about smoking induced early airway obstruction. And clinically potential parameters of IOS were considers that total resistance, peripheral resistance, bronchial resistance, and reactance of low frequency at 5Hz, 10Hz.

The Changes of Breathing Pattern Observed During Maximal Exercise Testing in the Patients with Chronic Airflow Obstruction: the Correlation Between the Change of Inspiratory Duty Cycle and the Degree of Airflow Obstruction / 결핵

BACKGROUND: Normal humans meet the increased ventilatory need during exercise initially by the increase of tidal volume (TV) and later by the increase of respiratory frequency (Rf). And the inspiratory duty cycle (Ti/Ttot) is also increased more than 50% for the compensation of the decrease of respiratory cycle provoked by the increase of respiratory frequency. The patients with chronic airflow obstruction show rapid and shallow breathing pattern during exorcise because of the degreased ventilatory capacity and the increased dead space ventilation. However, the studies about the change of inspiratory duty cycle are only a few and there is no literature about the relationship between the change of inspiratory duty cycle and the degree of airflow obstruction. METHODS: The subjects were the twelve patients with chronic airflow obstruction (CAO) and ten normal people. The incremental exercise test was done. The increase of work load was 10 Win CAO group and 25 Win normal control group. The analysis of the results was done by the comparison of the parameters such as minute ventilation (VE), TV, Rf, physiologic dead space (Vd/vt), and inspiratory duty cycle between the two groups. Each parameters were compared after transformation into % control duration base that means dividing the total exercise time into five fractons and % control duration data were obtained at rest, 20%, 40%, 60%, 80%, and max. Statistical analysis was done by repeated measure ANOVA using SAS program. RESULTS: The changes of VE and TV were significantly different between two groups while the change of Rf was not significant. The decrease of Vd/vt was significantly low in CAO group. Ti/Ttot was markedly increased from 38.4+3.0% at rest to 48.6+4.5% at max in normal control group while Ti/Ttot showed little change from 40.5+2.2% at rest to 42.6+3.5% at max. And the change of inspiratory duty cycle showed highly good correlation with the degree of airflow obstruction (FEVl%). (r=0.8151, p<0.05) CONCLUSIONS: The increase of Ti/Ttot during exercise observed in normal humans is absent in the patients with CAO and the change of Ti/TtDt is well correlated with the degree of airflow obstruction.