Dynamic Hyperinflation Correlates with Exertional Oxygen Desaturation in Patients with Chronic Obstructive Pulmonary Disease

Background

Dynamic hyperinflation (DH) causes exercise limitation and exertional dyspnea in patients with chronic obstructive pulmonary disease (COPD). Exertional desaturation (ED) also occurs commonly in COPD but neither routine physiologic parameters nor imaging predict ED accurately. In this study we evaluated the relationship between DH and ED during 6-min walk testing (6MWT).

Methods

We measured ED and DH in patients with stable COPD. SpO₂ was measured by continuous pulse oximetry during 6MWT. ED was defined as a decline in SpO₂ (ΔSpO₂) ≥4 %. DH was determined by measuring inspiratory capacity (IC) before and after the 6MWT using a handheld spirometer. DH was defined as ΔIC >0.0 L. We correlated DH and ED with clinical and pulmonary physiologic variables by regression analysis, χ ², and receiver operator curve (ROC) analysis.

Results

Thirty males [age = 65 ± 9.4 years, FEV₁ % predicted = 48 ± 14 %, and DLCO % predicted = 50 ± 21 % (mean ± SD)] were studied. ΔSpO₂ correlated with ΔIC (r = 0.49, p = 0.005) and age (r = 0.39, p = 0.03) by univariate analysis; however, only ΔIC correlated on multivariate regression analysis (p = 0.01). ΔSpO₂ did not correlate with FEV₁, FVC, FEF_25–75, RV, DLCO % predicted, BMI, smoking, BORG score, or distance covered in 6MWT. DH strongly correlated with ED (p = 0.001). On ROC analysis, DH had an area under the curve of 0.92 for the presence of ED (sensitivity = 90 %; specificity = 77 %, p < 0.001).

Conclusion

Routine pulmonary function test results and clinical variables did not correlate with ED in patients with stable COPD. Dynamic hyperinflation strongly correlates with exertional desaturation and could be a reason for this desaturation.     

慢性阻塞性肺疾病评估测试与深吸气量相关性研究

目的探讨COPD评估测试（CAT）应用于我国COPD患者生活质量的价值及深吸气量等肺功能指标与生命质量的关系。方法选择稳定期COPD患者62例,均进行功能检查,并进行CAT、SGRQ评分,采用Pearson直线相关分析CAT的评分与肺功能指标和SGRQ总分之间的相关性。结果 62例COPD稳定期患者的CAT评分为（20.5±7.4）分,肺功能检查结果中第1秒用力呼气容积占预计值（FEV1%pred）为（43.4±5.8）%,FEV1/FVC为（51.1±12.3）%,深吸气量占预计值%（IC%pred）为（73.2±19.4）%,SGRQ总分为（39.4±19.0）分。CAT与IC%pred、FEV1/FVC、SGRQ总分,均有相关性,CAT与FEV1%pred相关性差。结论 CAT是评价我国COPD生活质量的简易、有效、可行、标准化测量方法。CAT可与IC和FEV1联合作为临床评价COPD患者的客观指标。     

Chronic Exertional Dyspnea and Respiratory Muscle Function in Patients with Chronic Obstructive Pulmonary Disease

The symptom of breathlessness is an important outcome measure in the management of patients with chronic obstructive pulmonary disease (COPD). Clinical ratings of dyspnea and routine lung function are weakly related to each other. However, in the clinical setting breathlessness in COPD is encountered under conditions of increased respiratory effort, impeded respiratory muscle action, or functional weakness. Thus, the present study was carried out to determine whether and to what extent clinical ratings of dyspnea and respiratory muscle dysfunction relate to each other. In 21 patients with COPD two methods were used to rate dyspnea: a modified Medical Research Council Scale (MRC) and the Baseline Dyspnea Index (BDI), which is a multidimensional instrument for measuring dyspnea based on three components: magnitude of task, magnitude of effort, and functional impairment. A baseline focal score was obtained as the sum of the three components. Measures were: pulmonary volumes; arterial blood gases; maximal voluntary ventilation (MVV); maximal inspiratory and expiratory pressures (MIP and MEP, respectively); and breathing patterns ventilation (V_E), tidal volume (V_T), and respiratory frequency (Rf). In 15 patients pleural pressure was also measured during both quiet breathing (Ppl_sw) and maximal inspiratory sniff maneuver at FRC (Pplsn). BDI and MRC ratings related to each other and showed comparable weak associations with standard parameters (FEV₁, Paco ₂, V _T), MIP, and MEP. In contrast, MVV closely and similarly related to both ratings. Ppl_sw (%Ppl_sn), a measure of respiratory effort, and Ppl_sw (%Ppl_sn)/V _T(%VC), an index of neuroventilatory dissociation, related significantly to both the BDI (r ²=−0.77 and r ²=−0.75, respectively) and the MRC (r ²= 0.81 and r ²= 0.74, respectively). Using MVV, Ppl_sw (%Ppl_sn), and Ppl_sw (%Ppl_sn)/V _T(%VC) in a stepwise multiple regression as independent variables with BDI rating as dependent variable, MVV explained an additional 14.5% of the variance of the BDI over the 67.8% predicted by Ppl_sw (%Ppl_sn). Our results demonstrate that the level of chronic exertional dyspnea in COPD increases as the ventilatory muscle derangement increases. The level of the relationships among dyspnea ratings and MVV and respiratory effort helps to explain some of the mechanisms of chronic dyspnea of COPD. These measures should be considered for therapeutic intervention to reduce dyspnea. Accepted for publication: 30 December 1996     

Effect of Dynamic Hyperinflation on Cardiac Response to Exercise of Patients With Chronic Obstructive Pulmonary Disease

IntroductionAlthough the major limitation to exercise performance in patients with COPD is dynamic hyperinflation (DH), little is known about its relation with cardiac response to exercise. Our objectives were to compare the exercise response of stroke volume (SV) and cardiac output (CO) between COPD patients with or without DH and control subjects, and to assess the main determinants.MethodsFifty-seven stable COPD patients without cardiac comorbidity and 25 healthy subjects were recruited. Clinical evaluation, baseline function tests, computed tomography and echocardiography were conducted in all subjects. Patients performed consecutive incremental exercise tests with measurement of operating lung volumes and non-invasive measurement of SV, CO and oxygen uptake (VO₂) by an inert gas rebreathing method. Biomarkers of systemic inflammation and oxidative stress, tissue damage/repair, cardiac involvement and airway inflammation were measured.ResultsCOPD patients showed a lower SV/VO₂ slope than control subjects, while CO response was compensated by a higher heart rate increase. COPD patients with DH experienced a reduction of SV/VO₂ and CO/VO₂ compared to those without DH. In COPD patients, the end-expiratory lung volume (EELV) increase was related to SV/VO₂ and CO/VO₂ slopes, and it was the only independent predictor of cardiac response to exercise. However, in the regression models without EELV, plasma IL-1β and high-sensitivity cardiac troponin T were also retained as independent predictors of SV/VO₂ slope.ConclusionDynamic hyperinflation decreases the cardiac response to exercise of COPD patients. This effect is related to systemic inflammation and myocardial stress but not with left ventricle diastolic dysfunction.     

Peptic Ulceration in Patients with Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is frequently accompanied by peptic ulceration. Recent studies strongly suggest that the major cause is hypersecretion of gastric juice induced by hypoxemia or hypercapnia. To determine the incidence of peptic ulcers in COPD, we surveyed 267 patients with COPD seen at our hospital as inpatients or outpatients between 1984 and 1988. There were 90 patients with pulmonary emphysema, 93 with chronic bronchitis, and 84 with bronchiectasis. The prevalence of gastric ulcer in the patients with COPD was 23 out of the 267 patients (8.6%) surveyed. These included 13 patients with pulmonary emphysema, 6 with chronic bronchitis, and 4 with bronchiectasis. One-half of the patients with pulmonary emphysema had hypoxemia and hypercapnia: These observations suggest it is necessary to improve the abnormal blood gas concentration in patients with COPD in order to promote the healing of the peptic ulcer.     

Venous Thromboembolism in Patients with Chronic Obstructive Pulmonary Disease

ObjectiveOur aim was to compare the clinical characteristics, prophylaxis, treatment, and outcomes of venous thromboembolism in patients with and without previously diagnosed chronic obstructive pulmonary disease.MethodsWe analyzed the population-based Worcester Venous Thromboembolism Study of 2488 consecutive patients with validated venous thromboembolism to compare clinical characteristics, prophylaxis, treatment, and outcomes in patients with and without chronic obstructive pulmonary disease.ResultsOf 2488 patients with venous thromboembolism, 484 (19.5%) had a history of clinical chronic obstructive pulmonary disease and 2004 (80.5%) did not. Patients with chronic obstructive pulmonary disease were older (mean age 68 vs 63 years) and had a higher frequency of heart failure (35.5% vs 12.9%) and immobility (53.5% vs 43.3%) than patients without chronic obstructive pulmonary disease (all P < .0001). Patients with chronic obstructive pulmonary disease were more likely to die in hospital (6.8% vs 4%, P = .01) and within 30 days of venous thromboembolism diagnosis (12.6% vs 6.5%, P < .0001). Patients with chronic obstructive pulmonary disease demonstrated increased mortality despite a higher frequency of venous thromboembolism prophylaxis. Immobility doubled the risk of in-hospital death (adjusted odds ratio, 2.21; 95% confidence interval, 1.35-3.62) and death within 30 days of venous thromboembolism diagnosis (adjusted odds ratio, 2.04; 95% confidence interval, 1.43-2.91).ConclusionPatients with chronic obstructive pulmonary disease have an increased risk of dying during hospitalization and within 30 days of venous thromboembolism diagnosis. Immobility in patients with chronic obstructive pulmonary disease is an ominous risk factor for adverse outcomes.     

Difference Between Slow and Forced Vital Capacity and Its Relationship with Dynamic Hyperinflation in Patients with Chronic Obstructive Pulmonary Disease

The aim of the study was to investigate the relationship between slow and forced vital capacity (SVC–FVC) difference with dynamic lung hyperinflation (DH) during the 6-min walking test (6MWT) in subjects with chronic obstructive pulmonary disease (COPD). Twenty-four subjects with COPD (12 males; 67 ± 6 years; forced expiratory volume in first second [FEV₁] 56 ± 18% predicted) performed lung function tests by spirometry and plethysmography. DH was assessed by serial measurements of inspiratory capacity (IC) performed during the 6MWT and defined as ∆IC ≥ 150 mL or 10%. IC decrease significantly during the 6MWT (ΔCI: − 0.48 ± − 0.40 L; P < 0.0001), and 18 individuals (75%) presented DH. There was significant difference when comparing IC measured at rest with the other serial IC measurements (P < 0.0001). Correlation between the SVC–FVC difference and DH during the 6MWT was r = − 0.38; P = 0.06. The SVC–FVC difference presented only weak correlation with the development of DH during the 6MWT in patients with COPD.

     

Electrocardiographic Characteristics of Patients with Chronic Obstructive Pulmonary Disease

Abstract

Patients with chronic obstructive pulmonary disease (COPD) are at increased risk of cardiovascular disease. Electrocardiography (ECG) carries information about cardiac disease and prognosis, but studies comparing ECG characteristics between patients with and without COPD are lacking. We related ECG characteristics of patients with COPD, to ECG characteristics of patients without COPD, and determined whether ECG abnormalities are related to COPD severity. A cross-sectional study was conducted within a cohort of 243 COPD patients, aged 65 years or older. All patients underwent extensive examinations, including resting 12-lead ECG and pulmonary function tests. The reference group (n = 293) was a sample from the general population, also aged 65 or older, without COPD. Abnormal ECGs were more prevalent in COPD patients (50%) than in patients without COPD (36%, p = 0.054). Conduction abnormalities were the most common ECG abnormality in COPD patients (28%) being significantly more prevalent than in patients without COPD (11%, p < 0.001). The mean heart rate was higher in COPD patients (72 bpm (SD 14)) compared to controls (65 bpm (SD 13), p < 0.001), and QTc prolongation was less frequent in COPD patients (9% versus 14%, p = 0.01). The prevalence of ECG abnormalities increased with severity of pulmonary obstruction. ECG abnormalities, especially conduction abnormalities are common in COPD patients, and the prevalence of ECG abnormalities increases with severity of COPD. This underlines the importance of an integrated-care approach for COPD patients, paying attention to early detection of unrecognized coexisting cardiac disorders.     

Sleep Disordered Breathing in Patients with Chronic Obstructive Pulmonary Disease

Sleep-related disordered breathing (SDB) and its influence on desaturation were examined in stable COPD patients with waking SpO₂ > 90%. With respiratory inductance plethysmography, thoracic-abdominal respiratory movements for all events with more than 4% desaturation were analyzed in 26 patients. Types of SDB were confirmed by full polysomnography. Irregular breathing induced desaturation, while stable respiration continued during some desaturation events. Three types of altered ventilation were observed: hypoventilation, paradoxical movement and periodic breathing. An unusual type of paradoxical movement, with normal airflow despite progressive desaturation, was observed in REM sleep. Patients were divided into desaturation (15 patients) and non-desaturation (11 patients) groups. Daytime arterial blood gas, lung function values, and 6-min walking distance did not differ. Awake, mode, maximum and minimum nocturnal SpO₂ were lower in the desaturation group. SDB-induced desaturation events in the desaturation group were more frequent (9.2 ± 3.5 vs. 1.8 ± 2.2 times), a greater SpO₂ decrease (11.4 ± 7.1% vs. 5.2 ± 2.1%) and longer duration (73.2 ± 34.8 vs. 18.8 ± 39.0 min). Patterns of SDB in the desaturation group were hypoventilation (74.4 ± 23.4%), paradoxical movement (10.2 ± 14.5%), periodic breathing (12.1 ± 18.3%) and unclassified (5.8 ± 11.2%). These results reveal that lower SpO₂ and SDB influence nocturnal desaturation in stable COPD patients.     

Paraoxonase 1 Activity in Patients with Chronic Obstructive Pulmonary Disease

Introduction: Paraoxonase 1 (PON1) is an antioxidative enzyme manly associated with high density lipoproteins (HDL) in the peripheral blood. The aim of this study was to determine the PON1 paraoxonase and arylesterase activities in patients with chronic obstructive pulmonary disease (COPD). We also aimed to determine the concentration of reduced thiol groups as a marker of protein oxidation. Materials and methods: The study included 105 patients with stable COPD and 44 healthy controls. PON1 activities and thiols concentration were assayed in sera by spectrophotometry. Results: PON1 basal (POX) and salt-stimulated paraoxonase activity (POX1) as well as arylesterase activity (ARE) were significantly reduced in COPD patients. In addition, concentration of reduced thiol groups was significantly decreased in COPD group. PON1 activities were similar in patients with different disease severity (GOLD stages). However, a significant reduction in POX, POX1 and ARE was observed already in GOLD II stage when compared to controls. POX and POX1 showed modest while ARE yielded very good power for discrimination between healthy subjects and COPD patients. Univariate and multivariate logistic regression analysis indicated that ARE is a good COPD predictor. Conclusion: Reduction of PON1 activity observed in COPD patients could be partly caused by oxidative environment. Lower concentrations of reduced thiol groups in COPD patients suggest that a decrease in PON1 activity could reflect oxidative changes of enzyme free cysteine residues. Furthermore, decreased PON1 arylesterase activity might indicate a down-regulation of PON1 concentration. Our results suggest that ARE could be considered as potential biomarker for COPD diagnosis.     

Rehabilitation and supportive therapy in elderly patients with Chronic Obstructive Pulmonary Disease

Chronic Obstructive Pulmonary Disease (COPD) very often coexists with cardiovascular, musculoskeletal and metabolic comorbidities. This condition significantly impact on the general health, function, frailty and disability of such patients, and consequently on their prognosis. Indeed, complex and recurrent symptoms of general dysfunction are commonly present and burden on the health status.Symptomatic COPD patients, even with chronic and complex comorbidities or with different degree of severity, may benefit from rehabilitation including exercise and maintenance of physical activity, in order to reducing symptoms and restoring the highest possible level of independent function.This review will focus on the associated and relevant clinical problems of these patients at the onset of disability, methods of assessment and useful non-pharmacological treatments for caring and supporting them.     

Effects of Pulmonary Hypertension on Exercise Capacity in Patients With Chronic Obstructive Pulmonary Disease

IntroductionThe impact of pulmonary hypertension (PH) on exercise tolerance in chronic obstructive pulmonary disease (COPD) has not been fully elucidated. It is necessary to characterize pulmonary hemodynamics in patients with moderate to severe COPD in order to improve their management. The aim of the study was to determine whether in COPD the presence of PH is associated with reduced exercise tolerance in a cohort of stable COPD patients.MethodsCross-sectional analysis of 174 COPD patients clinically stable: 109 without PH and 65 with PH (COPD-PH). We assessed socio-demographic data, lung function, quality of life, dyspnea, cardiopulmonary exercise testing (CPET), constant workload endurance time (CWET), and six-minute walk test (6MWT). We elaborated a logistic regression model to explore the impact of PH on exercise capacity in COPD patients.ResultsCOPD-PH patients showed lower exercise capacity both at maximal (CPET) (43(20) versus 68(27) Watts and 50(19)% versus 71(18)% predicted peak oxygen consumption (VO₂peak), COPD-PH and COPD, respectively), and at submaximal tests (6MWT) (382(94) versus 486(95) m). In addition, the COPD-PH group had lower endurance time than the non-PH COPD group (265(113) s and 295(164) s, respectively).ConclusionsThe presence of PH is an independent factor that impairs exercise capacity in COPD.     

Social Determinants of Adherence to Pulmonary Rehabilitation for Chronic Obstructive Pulmonary Disease

Adherence to pulmonary rehabilitation (PR) is low. Previous studies have focused on clinical predictors of PR completion. We aimed to identify social determinants of adherence to PR. A cross-sectional analysis of a database of COPD patients (N = 455) in an outpatient PR program was performed. Adherence, a ratio of attended-to-prescribed sessions, was coded as low (<35%), moderate (35–85%), and high (>85%). Individual-level measures included age, sex, race, BMI, smoking status, pack-years, baseline 6-minute walk distance (6MWD: <150, 150–249, ≥250), co-morbidities, depression, and prescribed PR sessions (≤20, 21–30, >30). Fifteen area-level measures aggregated to Census tracts were obtained from the U.S. Census after geocoding patients' addresses. Using exploratory factor analysis, a neighborhood socioeconomic disadvantage index was constructed, which included variables with factor loading >0.5: poverty, public assistance, households without vehicles, cost burden, unemployment, and minority population. Multivariate regression models were adjusted for clustering on Census tracts. Twenty-six percent of patients had low adherence, 23% were moderately adherent, 51% were highly adherent. In the best fitted full model, each decile increase in neighborhood socioeconomic disadvantage increased the risk of moderate vs high adherence by 14% (p < 0.01). Smoking tripled the relative risk of low adherence (p < 0.01), while each increase in 6MWD category decreased that risk by 72% (p < 0.01) and 84% (p < 0.001), respectively. These findings show that, relative to high adherence, low adherence is associated with limited functional capacity and current smoking, while moderate adherence is associated with socioeconomic disadvantage. The distinction highlights different pathways to suboptimal adherence and calls for tailored intervention approaches.