Sleep architecture of short sleep time in patients with obstructive sleep apnea: a retrospective single-facility study.

PURPOSE: Sleep architecture consists of rapid eye movement (REM) sleep and non-REM sleep time. Non-REM sleep time is further classified into three stages by depth (stage N1-N3). Some studies have reported that short sleep time predicts all-cause mortality. Short sleep time can have characteristics of sleep architecture which contribute to poor prognosis. Obstructive sleep apnea (OSA) is a disease which causes cessation or decline of ventilation during sleep due to upper airway stenosis and affects sleep architecture. Few studies have reported on the sleep architecture of short sleep time in patients with OSA. Therefore, we aimed to observe this phenomenon. METHODS: From May 2008 to September 2021, patients diagnosed with OSA at our facility were assessed for clinical history and underwent full-night polysomnography (PSG). These patients were classified into two groups: total sleep time (TST) recorded on PSG consisting of a short TST (< 7 h) group and a not short TST (≥ 7 h) group. RESULTS: Of 266 patients with OSA, compared to the not short TST group (n = 131), the short TST group (n = 135) had a lower REM sleep time (%) and a higher stage N1 sleep time (%). There was a significant difference in age between the two groups, so sub-analyses classified the patients by age: non-elderly patients (< 65 years) and elderly patients (≥ 65 years) to adjust for age. Both sub-analyses showed similar results to the analysis for the combined ages regarding sleep architecture. CONCLUSION: Patients with OSA who had short sleep time had disordered sleep architecture with a lower REM sleep time (%) and more stage N1 sleep time.

Prognosis of patients with acute exacerbation of combined pulmonary fibrosis and emphysema: a retrospective single-centre study.

BACKGROUND: Previous analyses of combined pulmonary fibrosis and emphysema (CPFE) cohorts have provided conflicting data on the survival of patients with CPFE. Therefore, the aim of this study was to investigate the clinical prognosis of acute exacerbations (AE) of CPFE. METHODS: We retrospectively reviewed the medical records of patients who had been treated at the Shinshu University Hospital (Matsumoto, Japan) between 2003 and 2017. We identified 21 patients with AE of CPFE and 41 patients with AE of idiopathic pulmonary fibrosis (IPF) and estimated their prognoses using the Kaplan-Meier method. RESULTS: Treatment content and respiratory management were not significantly different between the two groups before and after exacerbation. At the time of AE, the median serum Krebs von den Lungen-6 level was significantly lower in the CPFE group (Krebs von den Lungen-6: 966 U/µL; white blood cell count: 8810 /µL) than that in the IPF group (Krebs von den Lungen-6: 2130 U/µL, p < 0.001; white blood cells: 10809/µL, p = 0.0096). The baseline Gender-Age-Physiology scores were not significantly different between the two groups (CPFE, 4.5 points; IPF, 4.7 points; p = 0.58). Kaplan-Meier curves revealed that the survival time after AE for patients with CPFE was longer than that for patients with IPF (p < 0.001, log-rank test). CONCLUSIONS: Survival prognoses after AE were significantly better for patients with CPFE than that for those with IPF. Our findings may improve the medical treatment and respiratory management of patients with AE-CPFE.

Virtual bronchoscopic navigation as an aid to CT-guided transbronchial biopsy improves the diagnostic yield for small peripheral pulmonary lesions.

BACKGROUND AND OBJECTIVE: Virtual bronchoscopic navigation (VBN) entails the provision of a virtual display of the bronchial routes that lead to small peripheral pulmonary lesions (PPL). It has been predicted that a combination of computed tomography (CT)-guided transbronchial biopsy (CT-TBB) with VBN might improve the diagnostic yield for small PPL. This study sought to investigate that prediction. METHODS: A total of 100 patients with small PPL (<20 mm) were enrolled for CT-TBB and randomly allocated to either a VBN+ or VBN- group (50 subjects per group). Group results were then compared in terms of diagnostic yield, whole procedure time, times at which the first CT scan and biopsy were taken and the number of lung biopsy specimens retrieved. RESULTS: The diagnostic yield for small PPL was significantly higher in the VBN+ group versus VBN- group (84% vs 58%, respectively (P = 0.013)), with no significant difference in (whole) examination time between groups (VBN+: 32:53 (32 min and 53 s) ± 12:01 vs VBN-: 33:06 ± 10:08 (P = NS)). However, the time periods between commencing the examination and either the first CT scan or first biopsy were significantly shorter for the VBN+ group, while the net biopsy time tended to be longer for this group with a significantly higher number of specimens collected (VBN+: 3.54 ± 1.07 specimens vs VBN-: 2.98 ± 1.06 specimens (P = 0.01)). CONCLUSION: Combining VBN with CT-TBB significantly improved the diagnostic yield for small PPL.

Bevacizumab-induced tracheoesophageal fistula in a patient suffering from lung cancer with bulky subcarinal lymph node: a case report.

A 66-year-old male with advanced non-small-cell lung cancer (NSCLC) who was previously treated with carboplatin, pemetrexed, and bevacizumab consequently suffered from severe coughing during deglutition. Chest computed tomography (CT) revealed a tracheoesophageal fistula (TEF) between the left main bronchus and esophagus through a subcarinal metastatic lymph node. Given the extreme swelling of the lymph node due to metastatic cancer, it was determined that the walls of the bronchus and esophagus had been injured simultaneously. Delayed and dysfunctional wound healing due to bevacizumab resulted in necrosis of the contact region leading to fistula formation. This case suggests that using bevacizumab for NSCLC in patients with bulky subcarinal lymphadenopathy may increase the risk for TEF.

The positional characteristics of patients with obstructive sleep apnea: a single institute retrospective study in Japan.

Obstructive sleep apnea (OSA) causes sleep-disordered breathing (SDB) due to upper airway obstruction. The severity of OSA changes with position during sleep. Patients with marked significant improvement in apnea-hypopnea index (AHI) level by sleep position change are defined as ''positional patients'' (PP), while those without improvement are defined as ''non-positional patients'' (NPP). We aimed to verify their clinical characteristics. Between May 2008 and May 2020, 237 patients with OSA were registered retrospectively and classified into two groups: PP (n = 158) and NPP (n = 79). The differences in clinical background and full-night polysomnography (PSG) between the two groups were observed. A logistic regression analysis was conducted to identify the risk factors for severe AHI (≥ 30 events/h) in the PP group. Moreover, confounding factor-adjusted sub-analysis by a propensity score matching method was performed, and the PSG results were compared between the two groups. The PP group was older than the NPP group. Furthermore, the PP group had lower body mass index (BMI) and AHI levels compared with the NPP group. The independent risk factors for severe AHI in the PP group were BMI and being in the supine position during sleep. The PP group had a significantly milder nocturnal hypoxemia despite having no significant difference in AHI levels between the two groups. The characteristics of PP were old age, low BMI, and low AHI associated with milder nocturnal hypoxemia. Moreover, they were less likely to worsen with nocturnal hypoxemia compared with NPP having similar severity.

Characteristics of airway resistance in obstructive sleep apnea patients with asthma on oscillometry.

BACKGROUND: Asthma and obstructive sleep apnea (OSA) are prevalent chronic respiratory disorders with a high tendency to coexist. Both diseases involve increased airway resistance in the upright position because of narrow upper or lower airways. Moreover, there is a marked increase in airway resistance in the supine position in patients with OSA. We verified the characteristics of OSA in combination with asthma. METHODS: Airway resistance was measured by oscillometry in the upright and supine position in 11 healthy participants (control), 59 patients with OSA alone, and 33 OSA patients with asthma (coexistence) in the hospital between April 2014 and July 2020. We compared the differences in airway resistance between the upright and supine positions among the three groups. In addition, we performed cephalometry to evaluate the upper airway structure in patients with OSA alone and in patients with both OSA and asthma. RESULTS: A marked increase in airway resistance due to postural change was observed in the "OSA alone" group compared to that in the control group. However, this was not observed in the "coexistence" and control groups. Moreover, the "coexistence" group had fewer structural abnormalities in the upper airway than the "OSA alone" group on cephalometry. CONCLUSIONS: The airway resistance of patients with OSA alone markedly increased with posture change because of upper airway abnormalities. However, there was a smaller increase with postural changes in OSA patients with asthma, suggesting the possibility of a smaller degree of upper airway abnormality compared to patients with OSA alone. CLINICAL TRIAL REGISTRATION NUMBER: This study is approved by the research ethics committee of the Shinshu University School of Medicine (permission number: 4272).

Usual Interstitial Pneumonia Pattern Interstitial Lung Disease Developed in a Patient with IgG4-related Chronic Sclerosing Sialadenitis.

A 69-year-old man was diagnosed with immunoglobulin (Ig) G4-related disease (IgG4-RD) at 62 years old. At that time, he had high serum IgG4 levels and bilateral submandibular gland swelling on CT; thus, a gland biopsy was performed. Because a reticular shadow was found on chest CT, a lung surgical biopsy was also performed. The specimens revealed usual interstitial pneumonia (UIP) pattern interstitial pneumonia with some IgG4-positive cells. The patient was subsequently followed up without treatment. His forced vital capacity and radiological findings progressively deteriorated, consistent with UIP pattern interstitial lung disease but different from a lung lesion of IgG4-RD.

Successful salvage chemotherapy with gemcitabine and vinorelbine in a malignant pleural mesothelioma patient previously treated with pemetrexed.

The role of second-line and salvage chemotherapy in malignant pleural mesothelioma treatment is not yet established. We report a case of relapsed malignant pleural mesothelioma in which the patient failed to respond to pemetrexed-based chemotherapy but was successfully treated with gemcitabine and vinorelbine. The patient underwent a left extrapleural pneumonectomy. Three years later she developed anterior chest wall and retroperitoneal masses. Histological findings revealed metastases from the malignant pleural mesothelioma. Although two cycles of carboplatin plus pemetrexed chemotherapy were administered, she had progressive disease. Then, 1000 mg/m(2) gemcitabine and 25 mg/m(2) vinorelbine were administered every 2 weeks. The chemotherapy regimen was tolerated well, and the tumors were remarkably reduced. She was treated with 12 cycles of gemcitabine plus vinorelbine, and 8.5 months of progression-free survival was observed. Gemcitabine plus vinorelbine chemotherapy may be a candidate regimen for salvage chemotherapy against malignant pleural mesotheliomas.

Iodine-123 metaiodobenzylguanidine scintigraphic assessment of pulmonary vascular status in patients with chronic obstructive pulmonary disease.

BACKGROUND AND OBJECTIVE: Lung uptake of iodine-123 metaiodobenzylguanidine (¹²³I-MIBG) is used as an indicator of pulmonary endothelial function. Decreased lung uptake of ¹²³I-MIBG has been demonstrated in patients with COPD as compared with normal subjects. The present study was performed to examine the relationship between lung uptake of ¹²³I-MIBG and pulmonary artery pressure (Ppa) at rest and during exercise, in patients with COPD. METHODS: ¹²³I-MIBG scintigraphy was performed in 19 patients with COPD. Anterior planar images were acquired 15 min after the injection of ¹²³I-MIBG, and the total lung to upper mediastinum ratio (LMR) was calculated for both lungs. Right heart catheters were used to monitor Ppa continuously at rest and during exercise. Exercise was performed on an electrically braked bicycle ergometer at a constant workload of 25 W for 3 min. RESULTS: In COPD patients the LMR were not correlated with the pulmonary function parameters measured before exercise, including FEV1, PaO2, DL(CO), or Ppa at rest. However, the percentage increase in Ppa during exercise was significantly correlated with LMR. CONCLUSIONS: Evaluation of the kinetics of lung uptake of ¹²³I-MIBG may be a novel scintigraphic tool for the assessment of exercise-induced pulmonary hypertension in patients with COPD.

Successful recovery from critical COVID-19 pneumonia with extracorporeal membrane oxygenation: A case report.

A public health emergency of current international concern is the outbreak of a severe respiratory illness, that is, coronavirus disease (COVID-19). The disease initially started in Wuhan, China, and it rapidly spread to most regions of the world. Herein, we report a case of critical COVID-19 pneumonia treated with extracorporeal membrane oxygenation from symptom onset day 19 (SOD#19) to SOD#30. We describe the patient's clinical course, from mild symptoms at the time of illness onset to symptoms of severe pneumonia as the illness progressed. We provide important information regarding our clinical experience for further understanding of management discrepancies, as treatment with extracorporeal membrane oxygenation or pharmacotherapy (e.g., antivirals, immunomodulators, and glucocorticoids) is often dependent on the severity of symptoms.

Airway hyper-responsiveness in young adults with asthma that remitted either during or before adolescence.

BACKGROUND AND OBJECTIVE: More than 50% of patients with childhood asthma enter clinical remission by puberty, although 40-50% of these people will probably develop asthma symptoms during early adulthood. The mechanism of relapsing asthma in early adulthood remains unclear. This study determined the characteristics of young adults whose asthma remitted either during or before adolescence. METHODS: A comparative study was performed on 24 students whose childhood asthma had gone into clinical remission by puberty (remission group), 25 atopic students with no history of asthma (atopy group) and 19 non-atopic students without allergic diseases (control group). Examinations included spirometry, levels of serum-specific IgE-antibodies, airway responsiveness to methacholine, exhaled nitric oxide (eNO) and evidence of airway inflammation in induced sputum. RESULTS: Airway responsiveness (P < 0.01), eosinophil counts in sputum (P < 0.05) and the prevalence of sensitization to Dermatophagoides forinae (P < 0.01) were significantly higher, and FEF(25-75%) and FEF(75%) (P < 0.01) were significantly lower in the remission group than in the atopy and control groups. Furthermore, 50% and 33% of the remission group had airway hyper-responsiveness (AHR) and sputum eosinophilia, respectively. The eNO levels in the remission (P < 0.01) and atopy (P < 0.05) groups were significantly higher than in controls. Remission group members with AHR had a significantly longer period of childhood asthma, a shorter period of remission and greater airway eosinophilic inflammation than those without AHR (P < 0.05). CONCLUSION: One half of young adults with childhood asthma that remitted either during or before adolescence continued to have evidence of AHR and airway eosinophilic inflammation, and might be at risk of future relapse.

A novel device (SD-101) with high accuracy for screening sleep apnoea-hypopnoea syndrome.

BACKGROUND AND OBJECTIVE: The SD-101 is a non-restrictive, sheet-like medical device with an array of pressure sensors, to detect sleep-disordered breathing by sensing gravitational alterations in the body corresponding to respiratory movements. This study evaluated the accuracy of the SD-101 for screening sleep apnoea-hypopnoea syndrome (SAHS) by comparison with polysomnography. METHODS: Nocturnal polysomnography and SD-101 monitoring were conducted simultaneously and compared in 201 patients with suspected SAHS (suspected SAHS group) and 165 male employees of a transport company (screening group). RESULTS: Polysomnography revealed an AHI of <5, 5 < or = AHI < 15, 15 < or = AHI < 30, 30 < or = AHI < 60 and AHI > or = 60 events/h in 39, 35, 38, 68 and 21 subjects in the suspected SAHS group and 103, 34, 12, 12 and four subjects in the screening group, respectively. Central SAHS and obstructive SAHS were subsequently diagnosed in 11 (5.5%) and 135 (67.2%) of subjects in the suspected SAHS group and five (3.0%) and 39 (23.6%) of subjects in the screening group, respectively. Significant correlations were apparent between AHI and the respiratory disturbance index (RDI) measured with the SD-101 in both the suspected SAHS group (r = 0.88) and screening group (r = 0.92). Receiver operating characteristic curve analysis revealed 89.5% sensitivity and 85.8% specificity in identifying SAHS, using an RDI of 14.0 events/h. CONCLUSIONS: These findings suggest that the SD-101 is a useful device for screening SAHS.

[A squamous cell lung cancer patient who developed immune hemolytic anemia after gemcitabine and docetaxel administration].

A 76-year-old man with squamous cell lung cancer underwent right lower lobectomy in November, 2005. He was diagnosed with pT2N0M0, stage I B, and tegafur/uracil (UFT) was administered. On July, 2007, right hilar lymphadenopathy was detected and considered to be a recurrence. UFT was discontinued, and gemcitabine (GEM) and docetaxel (DOC) combination chemotherapy was initiated on August 21. He began to complain of fatigue, palpitation and dizziness since the fifth day of the administration, and anemia (hemoglobin: Hb 8.7 g/dL) was detected on the fifteenth day. On the twenty-second day of the administration, he was admitted to our hospital because of aggravation of anemia (Hb 6.5 g/dL). His anemia was diagnosed as immune hemolytic anemia based on the laboratory findings including a positive Coombs' test. He showed improvement with prednisolone therapy. The anemia was considered to be drug-induced. This case was extremely rare, and there are no reports on immune hemolytic anemia related to GEM and/or DOC.

Twenty-year Follow-up of the First Bilateral Living-donor Lobar Lung Transplantation in Japan.

Patients with end-stage lung disease can undergo living-donor lobar lung transplantation (LDLLT), with survival rates improving every year. We herein report the 20-year follow-up findings of the first patient who underwent LDLLT in Japan. A 24-year-old woman with primary ciliary dyskinesia became ventilator-dependent after severe respiratory failure and right-sided heart failure following repeated respiratory infections. In 1998, she underwent LDLLT and received her sister's right lower lobe and her mother's left lower lobe. Although the patient required 21 hospitalizations and developed unilateral bronchiolitis obliterans syndrome, she is in good physical condition and lives without restriction at 20 years after undergoing LDLLT.

Leptin and leptin receptor gene polymorphisms in obstructive sleep apnea syndrome.

BACKGROUND: Obstructive sleep apnea is common in obese people. Leptin is an adipocyte-derived signaling factor that has an important role in metabolic control. There is growing evidence that leptin regulation is altered in obstructive sleep apnea syndrome (OSAS). The aim of this study was to investigate the relation between polymorphisms of the leptin and leptin receptor (LEPR) genes and OSAS. METHODS: The study population consisted of 130 patients with OSAS and 50 healthy control subjects. All the subjects were Japanese. Diagnostic polysomnography was performed in all patients and control subjects. A highly polymorphic tetranucleotide repeat polymorphism in the 3'-flanking region of the leptin gene and three single nucleotide polymorphisms (SNPs) [Lys109Arg (A/G) in exon 4, Gln223Arg (A/G) in exon 6, and Lys656Asn (G/C) in exon 14] in the LEPR gene were examined. RESULTS: There were no significant differences in allelic frequencies and genotype distributions of the examined polymorphisms of the leptin and LEPR genes between OSAS patients and control subjects. For the LEPR gene, the wild-type alleles of the Gln223Arg and Lys656Asn SNPs had a marginally significant effect on mild OSAS, which was defined as an apnea-hypopnea index from 10 and 20 events/h in the dominant model. CONCLUSIONS: The tetranucleotide repeat polymorphism of the leptin gene and the Lys109Arg, Gln223Arg, and Lys656Asn SNPs in the LEPR gene were not associated with OSAS in the Japanese population. Further studies are required to confirm the association of the wild types of Gln223Arg and Lys656Asn SNPs with the severity of OSAS.

Reduced lung uptake of iodine-123 metaiodobenzylguanidine in high-altitude pulmonary oedema.

BACKGROUND AND OBJECTIVE: Iodine-123 metaiodobenzylguanidine ((123)I-MIBG) uptake in the lungs is a potentially suitable marker of pulmonary endothelial function because MIBG behaviour in the pulmonary circulation is quantitatively similar to that of norepinephrine. In addition, hypoxia reduces (123)I-MIBG transport in pulmonary endothelial cells in vitro. The present study was undertaken to evaluate (123)I-MIBG uptake in the lungs of patients with high-altitude pulmonary oedema (HAPE). METHODS: (123)I-MIBG scintigraphy was performed in eight patients with HAPE. The findings were compared with those in 24 patients with congestive heart failure due to idiopathic dilated cardiomyopathy (DCM) and in 13 normal control subjects. In patients with HAPE, the (123)I-MIBG examination was performed 7-14 days after admission. Anterior planar images were acquired 15 min after injection of (123)I-MIBG and the total lung to upper mediastinum ratio (L/M ratio) was calculated for both lungs. RESULTS: The L/M ratio in patients with HAPE (1.39 +/- 0.15, mean +/- SD) was significantly lower than in those with congestive heart failure/DCM (1.66 +/- 0.16) or in normal controls (1.53 +/- 0.14). There were no significant differences among the groups in (123)I-MIBG accumulation in the heart. CONCLUSIONS: Although the mechanism of altered (123)I-MIBG kinetics in HAPE remains obscure, decreased (123)I-MIBG uptake in the lungs may potentially be a suitable technique for the assessment of pathological conditions associated with the pulmonary endothelium.

Pulmonary haemodynamic changes in patients with severe COPD.

Worsening gas exchange during exercise and during exacerbations of COPD contributes to systemic hypoxaemia and reduces quality of life. However, pulmonary haemodynamic changes under such conditions are not well understood. Right heart catheterization was performed in six patients with severe COPD (%FEV(1) < 50%) during rest, exercise and during an exacerbation. Pulmonary artery pressure (Ppa) was slightly elevated at rest. The Ppa, as well as pulmonary artery wedge pressure (Pawp) and cardiac index were significantly increased during bicycle ergometer exercise. In contrast, pulmonary vascular resistance increased significantly during an exacerbation accompanied by a slightly increased Ppa. Supplemental oxygen resulted in significant decreases in Ppa and Pawp during exercise and Ppa during exacerbations. In patients with COPD, haemodynamic changes in the pulmonary circulation may differ during exercise and with exacerbations. Supplementary oxygen is beneficial and associated with reductions in pulmonary arterial pressures.

Usefulness of the forced oscillation technique in assessing the therapeutic result of tracheobronchial central airway obstruction.

BACKGROUND: Pulmonary function tests (PFTs) comprise the traditional method for detecting central airway obstruction (CAO) and evaluating therapeutic effects, but are effort-dependent. By contrast, the forced oscillation technique (FOT) is performed during tidal breathing in an effort-independent mode and is universally used to assess respiratory function in patients with chronic obstructive pulmonary disease (COPD) and asthma. We used the FOT to measure airway resistance and reactance in patients with CAO before and after interventional bronchoscopy and compared the results to data obtained using PFTs. METHODS: Twelve patients with CAO were recruited from December 2013 to July 2016. The FOT, PFTs, chest computed tomography (CT), COPD Assessment Test (CAT), and the modified Medical Research Council (mMRC) dyspnea scale were employed before and after interventional bronchoscopy. The minimum airway cross-sectional area (MACSA) was calculated using a CT image calculator. RESULTS: Of the 12 patients, 6 had tracheal obstruction and 6 had bronchial obstruction. All FOT measurements, except ΔX5, were significantly improved after interventional bronchoscopy in all cases. The significance of the improvement was greater with the FOT than PFTs. The MACSA, CAT, and mMRC dyspnea scale scores also significantly improved in all cases. Furthermore, only alteration of resistance at 20 Hz (R20) significantly correlated with the alteration of the MACSA after intervention. No significant correlations were found for PFTs. CONCLUSIONS: The FOT is suitable and convenient for assessing therapeutic results in patients with tracheobronchial CAO. The alteration of R20 is useful for estimating the airway dilation of CAO after interventional bronchoscopy.

Second-line chemotherapy of platinum compound plus CPT-11 following ADOC chemotherapy in advanced thymic carcinoma: analysis of seven cases.

BACKGROUND: Optimal chemotherapeutic regimen in thymic carcinoma remains uncertain and the efficacy of second line chemotherapy has not been established either. PATIENTS AND METHODS: We retrospectively evaluated the efficacy of an irinotecan plus cisplatin or carboplatin (IP) regimen as a salvage treatment for patients with unresectable thymic carcinoma that progressed after cisplatin, doxorubicin, vincristine and cyclophosphamide (ADOC) chemotherapy. Seven patients with histologically confirmed thymic carcinoma that was resistant to or who had relapsed after initial chemotherapy with ADOC were treated with IP. The treatment consisted of irinotecan (CPT-11, 60 mg/m2, days 1, 8 and 15) and cisplatin (80 mg/m2, day 1) or carboplatin (AUC 4) intravenously every 4 weeks, for at least 2 cycles. RESULT: Two patients achieved partial responses. Although another two patients showed a significant reduction of the primary thoracic lesion, the appearance of a new lesion was found in one and a metastatic lesion was unchanged in the other. Neutropenia over grade 3 was observed in all patients but none of the patients developed serious infections. There were no severe non-hematological toxicities, including diarrhea. CONCLUSION: We conclude that salvage chemotherapy may be useful in certain patients with thymic carcinoma and irinotecan may be a novel and alternative agent for relapsed thymic carcinoma.

Associations between the distance covered in the incremental shuttle walk test and lung function and health status in patients with chronic obstructive pulmonary disease.

BACKGROUND: Field walk tests such as the incremental shuttle walk test (ISWT) are simple tests for assessing the degree of disability in individuals with chronic obstructive pulmonary disease (COPD). In the present study, the correlations between exercise performance in the ISWT, lung function, and health status were examined in patients with COPD of varying severities. METHODS: A retrospective examination of 277 COPD patients was performed using the ISWT and lung function tests along with assessment of health status using St. George׳s Respiratory Questionnaire (SGRQ). In addition, we assessed the correlations between the walking distance, lung function parameters, and SGRQ scores. RESULTS: ISWT distances were poorly correlated with lung function parameters and SGRQ scores in mild COPD patients. In contrast, ISWT distances were significantly correlated with pulmonary function parameters, such as vital capacity (%predicted) and forced expiratory volume in one second, and SGRQ scores in moderate and severe COPD patients. CONCLUSIONS: The ISWT is more independent of health status and pulmonary function in patients with mild COPD compared to moderate or severe cases. Therefore, the exercise capacity of patients with mild COPD should be estimated by the ISWT.