Dyspnea and ventilatory muscle function during exercise on air and oxygen breathing in patients with chronic obstructive pulmonary disease (COPD)]

Exercise performance and dyspnea in COPD patients have been shown to be improved with supplemental oxygen, although the exact mechanisms resulting in the improvement are still unclear. The purpose of the present study was to investigate a possible relationship between ventilatory muscle function and sensation of dyspnea (modified Borg Scale) during exercise on 20% O2 and 30% O2. Eight patients with COPD (FEV1 1.06 L +/- 0.30 L) exercised on a treadmill two times breathing compressed air or 30% oxygen with a one hour rest in between. The electrical activity of the diaphragm (EMGdi) was recorded with esophageal electrodes, and that of the sternomastoid muscle (EMGsm) was recorded from the fine wire electrodes. The ratio of high frequency (150 to 350 Hz) to low frequency (20 to 47 Hz) power (H/L) of EMGdi was analyzed to assess diaphragmatic fatigue, which was defined as a 20% fall of H/L ratio from the control value. Flow, volume, O2 Saturation (SaO2), esophageal pressure (Pes) and transdiaphragmatic pressure (Pdi) were measured. Tension time index (TTdi) was calculated from Pdi and the ratio of inspiratory time to total time for one cycle (Ti/Ttot). At rest, we measured maximal esophageal pressure (Pesmax), maximal transdiaphragmatic pressure (Pdimax), maximal integrated EMGdi (EMGdimax) and EMGsm (EMGsmmax). Incremental exercise was discontinued by dyspnea. The walking distance achieved was increased in all patients on 30% O2. Dyspnea and desaturation were significantly improved on 30% O2 breathing, and the onset of diaphragmatic fatigue was delayed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ventricular performance during exercise in patients with chronic obstructive pulmonary disease (COPD)]

We assessed ventricular performance during exercise in 16 COPD patients and 8 normal control subjects by means of radionuclide equilibrium angiography using technetium-99m as a tracer. Supine exercise on a bicycle ergometer was performed until symptom-limited exhaustion. Data were accumulated for 300 heart beats at rest and 150 heart beats during exercise. We used the standard voxel count method to calculate the ventricular volumes. Age, FEV1.0%, %VC, PaO2 and PaCO2 of the COPD patients were 63 +/- 8 yr, 46 +/- 11%, 69 +/- 18%, 68 +/- 11 Torr and 44 +/- 7 Torr (mean +/- SD), respectively. Systolic dysfunction of both the left and right ventricles was well confirmed in the present study. In 12 patients who also underwent hemodynamic studies, resting total pulmonary vascular resistance index (TPVRI) and mean pulmonary artery pressure (Ppa) significantly correlated with right ventricular end-systolic volume index (RVESVI) obtained by RI angiography; gamma = 0.769 (p less than 0.01) and gamma = 0.631 (p less than 0.05), respectively. A significant relationship was also observed between left ventricular dysfunction and the degree of hypercapnia. In response to exercise testing, 10 of 16 patients exhibited insufficient augmentation of stroke volume, and both left and right end-diastolic volumes decreased in half of 10 patients. It is suggested that cardiac function may be disturbed by mechanical factors such as pulmonary hyperinflation in COPD patients.     

Cardiac arrhythmias during exercise in severe chronic obstructive pulmonary disease

We studied the effect of maximal exercise on the prevalence of arrhythmias in 122 subjects with severe COPD. At rest, ten subjects had supraventricular arrhythmias while 13 had unifocal VPB greater than or equal to 6/min or ventricular bigeminy. At peak exercise, six subjects had supraventricular arrhythmias while 24 had VAs. Univariate and multivariate analysis with logistic regression did not show relationships between exercise-related cardiac arrhythmias and the severity of pulmonary disease, oxyhemoglobin desaturation or ECG evidence of chronic lung disease. Exercise-related arrhythmias were significantly associated with the presence of arrhythmias at rest and 87 percent of subjects who had no arrhythmias at rest did not have any during exercise. In patients with COPD, the development of potentially serious arrhythmias during exercise is uncommon without clinically apparent CAD or arrhythmias at rest. However, routine cardiac monitoring during exercise testing should not be abandoned in this population since VAs can occur despite their absence at rest.     

慢性阻塞性肺疾病的呼吸困难

呼吸困难是慢性阻塞性肺疾病(chronic obstructive pulmonary disease,COPD)的首要症状,也是COPD患者最痛苦的症状.COPD诊断、处理和预防全球策略2011年报告推荐采用修订版呼吸困难分级(the modified Medical Research Council Dyspnea Scale,mMRC)评估COPD患者的呼吸困难,对mMRC达到和(或)超过2分的患者积极进行药物干预,以缓解呼吸困难.指南建议转化到临床实践的过程中,医师需要认识COPD呼吸困难的发生机制;理解呼吸困难测量工具的测定原理,包括信度、效度、对呼吸困难变化的敏感度;各种新老药物缓解呼吸困难的疗效.这篇文章从呼吸困难发生机制、呼吸困难测量、呼吸困难治疗三方面,综述COPD呼吸困难的最新进展.     

Maximum inspiratory muscle endurance capacity during resistive loading in chronic obstructive pulmonary disease

In 10 patients with stable severe chronic obstructive pulmonary disease (COPD) we evaluated the relationship between the degree of airway obstruction and hyperinflation, and the maximum inspiratory muscle endurance capacity during added inspiratory resistive loading. We measured the ratio of forced expiratory volume in 1 s to forced vital capacity (FEV1/FVC) and airway resistance (Raw) as indices of airway obstruction, and the ratio of functional residual capacity to total lung capacity (FRC/TLC) as an index of hyperinflation. The mean resting transdiaphragmatic pressure to its maximum (Pdi/Pdimax), the tension time index of the diaphragm, and the maximum transdiaphragmatic pressure (Pdimax) were also determined. Following 15 min of resting breathing, the patients breathed through added inspiratory resistances which were progressively increased every 3 min until exhaustion. Maximum endurance capacity (ECmax) was defined as the product of the esophageal pressure - time integral and frequency at the maximum load sustainable for 3 min. ECmax correlated significantly with Raw (r = -0.67, p less than 0.04). The addition of FRC/TLC to the analysis resulted in a significant increase in the correlation coefficient (r = 0.86, p less than 0.01). ECmax did not correlate with FEV1/FVC. Both resting Pdi/Pdimax and Pdimax independently influenced ECmax. In addition, Pdimax correlated significantly with FRC/TLC, and resting Pdi/Pdimax with Raw. We conclude that in stable patients with severe COPD, both airway obstruction and hyperinflation affect maximum inspiratory muscle endurance capacity during inspiratory resistive loading.     

Low body mass index and exercise capacity in patients with chronic obstructive pulmonary disease (COPD)]

This study examined retrospectively the relationships between body weight and exercise capacity in patients with chronic obstructive pulmonary disease (COPD). Seventeen patients with a %FEV1 less than 55% (mean +/- SD 36% +/- 8.8%) and minimum body weights of the body mass index (BMI) less than 20 (17.3 +/- 1.7) performed incremental exercise testing using a treadmill. Seventeen %FEV1-matched control patients with normal body weights were selected. There were no significant differences in the patients' characteristics or their pulmonary function tests (including vital capacity, carbon monoxide diffusing capacity, and arterial blood gases). Low BMI patients Is this the weaning of (67.8 +/- 6.3 years old) were younger than the control patients (73.1 +/- 8.5 years old), but the difference was not statistically significant. The exercise capacities of low BMI patients were significantly superior to those of the control patients (316.5 +/- 171.5 seconds vs 204.1 +/- 116.3 seconds, p = 0.038) and total walking distance without statistical significance (194.9 +/- 117.0 m vs 125.7 +/- 98.0 m, p = 0.071). Also, low BMI patients achieved higher maximal minute ventilation volume during exercise than the controls. The major factor limiting exercise in patients with low BMI was ventilation. Moderately low body weight may not be a risk factor in Japanese COPD patients.     

The effects of pulmonary rehabilitation with chronic obstructive pulmonary disease (COPD)]

It is controversial whether pulmonary rehabilitation is effective in patients with chronic obstructive pulmonary disease (COPD). To test the effect of pulmonary rehabilitation, 7 patients with COPD (aged 76.0 +/- 2.6 years) were enrolled in pulmonary rehabilitation program for 6 weeks. The program consisted of relaxation, pursed lip breathing, diaphragmatic breathing, panic control, muscle stretch gymnastics, and exercise training. The distance of the 6-minute walking test increased significantly from 246.4 +/- 38.0 (m) to 304.3 +/- 28.4 (m) (p < 0.05). The minimum SpO2 during the 6-minute walking test increased from 86.0 +/- 2.8 (%) to 90.1 +/- 1.3 (%) and dyspnea as measured with Borg scale decreased from 5.6 +/- 1.1 to 4.6 +/- 0.5, although they were not significantly different. These results suggest that pulmonary rehabilitation might improve exercise tolerance in elderly patients with COPD.     

High-intensity inspiratory muscle training in patients with chronic obstructive pulmonary disease and severely reduced function

PURPOSE: This study examined the effects of inspiratory muscle training (IMT) with high-intensity inspiratory pressure loads on respiratory muscle performance and exertional dyspnea. METHODS: This was a randomized single-blind clinical trial. Twenty-seven patients with chronic obstructive pulmonary disease (18 men, 9 women) with severe to very severe airflow obstruction and severely limited functional performance were assigned randomly to an IMT group (n = 12) or an educational control group (n = 15). The IMT group trained with a threshold loaded device for 30 minutes a day for 16 weeks using interval training techniques. Training was initiated with inspiratory pressure loads equal to 30% of maximal inspiratory pressure (Plmax) and increased as tolerated to 60% of Plmax. Dependent variables were measured before and after 4 months of IMT: inspiratory muscle strength (Plmax), respiratory muscle endurance (discontinuous incremental threshold loading test [DC-ITL]), dyspnea (Chronic Respiratory Disease Questionnaire [CRQ]), and the Borg Category-Ratio Scale ratings of perceived breathing difficulty (RPBD) at equal loads during the DC-ITL. RESULTS: In the IMT group, Plmax increased from 64 +/- 15 to 75 +/- 17 cm H2O (P < .05), performance on the DC-ITL test increased from a maximal load of 37 +/- 12 to 53 +/- 13 cm H2O (P < .05), RPBD decreased from 5.5 +/- 2.5 to 3.8 +/- 2.6 for equal loads on the DC-ITL (P < .05) and the CRQ Dyspnea Scale improved from 18.1 +/- 5.1 to 22.4 +/- 5.2 (P < .05). CONCLUSIONS: Inspiratory muscle training at high-intensity loads significantly improved inspiratory muscle strength, respiratory muscle endurance, and respiratory symptoms during daily activities and respiratory exertion.     

Correlates of arterial oxygenation during exercise in severe chronic obstructive pulmonary disease

In the present study, we have undertaken a detailed analysis of the respiratory physiologic correlates of SaO2 during mild constant-load exercise in 38 patients with severe but stable COPD. Several respiratory physiologic variables that would be expected to influence exercise SaO2 were entered into a stepwise multiple linear regression analysis with mean exercise SaO2 as the dependent variable. Two variables (Dco and resting SaO2) were found to correlate strongly with mean exercise SaO2 (multiple r = 0.80; p less than 0.00001) and accounted for 65 percent of the variability among patients. The PaCO2 influenced resting SaO2 but had no independent influence on exercise SaO2. Subsequently, the model of mean exercise SaO2 derived in the present analysis was found to accurately predict mean exercise SaO2 in a group of 19 similar patients (r = 0.85; p less than 0.0001). While these findings do not establish a cause-and-effect relationship, they may provide clinicians with further insight as to which patients are likely to desaturate during exercise.     

Cycle ergometer and inspiratory muscle training in chronic obstructive pulmonary disease.

In patients with chronic obstructive pulmonary disease (COPD) the intensity of aerobic training is limited by dyspnea. Improving strength of the inspiratory muscles could enhance aerobic exercise training by reducing exercise-related dyspnea. We examined effects of home-based inspiratory muscle training (IMT) and cycle ergometry training (CET) in 53 patients with moderate to severe COPD (FEV(1)% pred, 50 +/- 17 [mean +/- SD]). Patients were randomly assigned to 4 mo of training in one of four groups: IMT, CET, CET + IMT, or health education (ED). Patients were encouraged to train to the limits of their dyspnea. Inspiratory muscle strength and endurance increased in IMT and CET + IMT groups compared with CET and ED groups (p < 0. 01). Peak oxygen uptake increased and heart rate, minute ventilation, dyspnea, and leg fatigue decreased at submaximal work rates in the CET and CET + IMT groups compared with the IMT and ED groups (p < 0. 01). There were no differences between the CET and CET + IMT groups. Home-based CET produced a physiological training effect and reduced exercise-related symptoms while IMT increased respiratory muscle strength and endurance. The combination of CET and IMT did not produce additional benefits in exercise performance and exercise-related symptoms. This is the first study to demonstrate a physiological training effect with home-based exercise training.     

Targeted inspiratory muscle training improves respiratory muscle function and reduces dyspnea in patients with chronic obstructive pulmonary disease

STUDY OBJECTIVE: To examine the effects of targeted inspiratory muscle training on respiratory muscle function, clinical ratings of dyspnea, and perception of resistive loads in symptomatic patients with chronic obstructive pulmonary disease. DESIGN: Randomized, placebo-controlled trial with an 8-week treatment period. SETTING: Outpatient pulmonary clinic and pulmonary function laboratory. PARTICIPANTS: We studied 19 patients with moderate to severe chronic obstructive pulmonary disease, assigning 10 patients to an experimental group and 9 to a control group. INTERVENTIONS: Patients in both groups trained for 15 minutes twice each day using a device that provided breath-to-breath visual feedback of training intensity. Patients in the experimental group trained at six increasing levels of inspiratory resistance, whereas the patients in the control group trained at a constant, nominal level of resistance. MEASUREMENTS AND RESULTS: Although there was no statistically discernible difference in the effects of targeted muscle training on the mean difference in maximal inspiratory pressures between the two groups (9.83 cm H2O; 95% CI, -7.37 to 27.03), patients in the experimental group did show a significant increase in inspiratory muscle strength (15.03 cm H2O; P = 0.01). Experimental subjects also had decreased dyspnea after 8 weeks of training compared with control subjects (P = 0.003). Improvements in physiologic values and in dyspnea ratings were correlated. The perception of added resistive loads was not affected by inspiratory muscle training. CONCLUSIONS: Targeted inspiratory muscle training may enhance respiratory muscle function and reduce dyspnea in symptomatic patients with moderate to severe chronic obstructive pulmonary disease.     

慢性阻塞性肺疾病的呼吸肌功能

慢性阻塞性肺疾病患者常存在呼吸肌收缩力和(或)耐力下降,引起呼吸困难,限制患者活动能力,使患者的运动量减少,日常生活质量降低;如果病情得不到控制,可以导致高碳酸性呼吸衰竭,严重者造成患者死亡.呼吸肌功能评价在慢性阻塞性肺疾病患者临床病情评估和预后判断方面很有应用价值.最大吸气压和最大呼气压测定是临床最常用的、可信的、非创伤性的评价呼吸肌功能的指标.研究结果显示最大吸气压较一秒量敏感.呼吸肌本身的病理改变和肺过度充气导致膈肌的收缩初长度缩短等原因可以引起呼吸肌功能障碍.可以应用抗胆碱药物、β2-受体激动剂、运动训练、营养支持及同化激素、心理支持、患者教育等治疗慢性阻塞性肺疾病呼吸肌功能障碍.蛋白酶抑制剂、过氧化物酶体增殖物激活受体、硫酸镁有希望成为治疗慢性阻塞性肺疾病呼吸肌功能障碍的方法.     

慢性阻塞性肺疾病患者运动负荷初期血流动力学应答的探究

目的实验通过恒定运动负荷试验观测慢性阻塞性肺疾病（ＣＯＰＤ）及正常人于室内空气和吸氧时运动负荷初期（运动负荷后１～３分钟）血流动力学变化，探究运动负荷初期血流动力学应答检测对ＣＯＰＤ肺动脉高压诊断及疗效评价的可行性。方法采用右心导管动态观测其肺动脉平均压（ｍＰＡＰ），心排血量（ＣＯ）及混合静脉血氧饱和度（ＳｖＯ２）。结果与对照组比较，ＣＯＰＤ组于室内空气和吸氧时运动负荷初期ＰＡＭＰ均明显增高，ＳｖＯ２明显降低，ＣＯ呈逐渐增加趋势，且运动负荷３分钟时血流动力学变化与１５分钟时差异无显著性。ＣＯＰＤ组ｍＰＡＰ及ＳｖＯ２于运动负荷后达到相对恒定明显迟于对照组，但吸氧可缩短ＣＯＰＤ组ｍＰＡＰ和ＳｖＯ２到达相对恒定的时间，且接近对照组。结论检测ＣＯＰＤ运动负荷初期血流动力学应答对ＣＯＰＤ肺动脉高压诊断及疗效判定有重要的临床意义。     

Hemodynamics of patients with severe chronic obstructive pulmonary disease during progressive upright exercise

This study evaluated the relationship between the oxygen consumption (VO2) and cardiac output and heart rate during progressive exercise in the upright position in 26 patients with severe chronic obstructive pulmonary disease. Forced expiratory volume in one second (FEV1) was 0.82 +/- 0.21 L, and single-breath carbon monoxide diffusing capacity was 39 +/- 20% predicted. Cardiac outputs were measured by the direct Fick method. The patients as a group had a normal cardiac output for the level of VO2. The mean pulmonary artery pressure in our patients (22.5 +/- 10.1 mmHg) was increased at rest; during exercise, it increased abnormally to 45.5 +/- 18.9 mmHg. The heart rates were increased both at rest and during exercise, and the increase in heart rate for an increase in VO2 was higher than normal. The relative tachycardia observed was probably related to a combination of abnormal arterial blood gases, concomitant bronchodilator administration, deconditioning, and right ventricular dysfunction. The relative tachycardia did not appear to have an adverse effect on exercise tolerance because the ratio of maximal exercise ventilation to the FEV1 exceeded 35 in those patients with observed maximal heart rates above 90% of predicted. The results of this study suggest that improvements in the exercise tolerance of these patients is dependent upon improving their ventilatory capabilities or the efficacy of their ventilation.     

Diaphragm activation during exercise in chronic obstructive pulmonary disease

Although it has been postulated that central inhibition of respiratory drive may prevent development of diaphragm fatigue in patients with chronic obstructive pulmonary disease (COPD) during exercise, this premise has not been validated. We evaluated diaphragm electrical activation (EAdi) relative to maximum in 10 patients with moderately severe COPD at rest and during incremental exhaustive bicycle exercise. Flow was measured with a pneumotachograph and volume by integration of flow. EAdi and transdiaphragmatic pressures (Pdi) were measured using an esophageal catheter. End-expiratory lung volume (EELV) was assessed by inspiratory capacity (IC) maneuvers, and maximal voluntary EAdi was obtained during these maneuvers. Minute ventilation (V E) was 12.2 +/- 1.9 L/min (mean +/- SD) at rest, and increased progressively (p < 0.001) to 31.0 +/- 7.8 L/min at end-exercise. EELV increased during exercise (p < 0.001) causing end-inspiratory lung volume to attain 97 +/- 3% of TLC at end-exercise. Pdi at rest was 9.4 +/- 3.2 cm H(2)O and increased during the first two thirds of exercise (p < 0.001) to plateau at about 13 cm H(2)O. EAdi was 24 +/- 6% of voluntary maximal at rest and increased progressively during exercise (p < 0.001) to reach 81 +/- 7% at end-exercise. In conclusion, dynamic hyperinflation during exhaustive exercise in patients with COPD reduces diaphragm pressure-generating capacity, promoting high levels of diaphragm activation.     

Pulmonary hemodynamics during exercise in anesthetized dogs with inspiratory loading and in patients with chronic obstructive pulmonary disease

We studied 1) the effects of inspiratory elastic loading on pulmonary hemodynamics and pulmonary gas exchange with and without electrically induced hindlimb exercise in 8 anesthetized dogs, 2) pulmonary hemodynamics at rest and during single stage exercise on a supine cycle ergometer in 6 patients with chronic obstructive pulmonary disease (COPD) and 3) changes in P wave height in lead II of electrocardiogram during progressive exercise on a treadmill in 9 COPD patients. The pulmonary arterial pressure-flow relationship from resting to exercise was not affected by inspiratory elastic loading, but elastic loading accompanied by exercise increased alveolar-arterial O2 tension difference (AaDO2). The pulmonary arterial pressure-flow relationship in COPD from rest to exercise showed higher pulmonary vascular resistance than that in control group. Moreover, we found a greater increase in P wave height during exercise in COPD with decrease in PaO2 during exercise than in COPD without decrease in PaO2 during exercise. This increase in P wave height during exercise was inhibited by oxygen inhalation. We speculated that 1) increased AaDO2 during exercise with elastic loading may be due to increased shunt effects with low ventilation-perfusion ratio and 2) increased P wave height during exercise in COPD may be correlated with hypoxia during exercise and may be useful to detect latent cor pulmonale in COPD.     

Repeated waon therapy improves pulmonary hypertension during exercise in patients with severe chronic obstructive pulmonary disease

OBJECTIVES: Repeated Waon therapy, which uses a far infrared-ray dry sauna system, improved the vascular endothelial function and the cardiac function in patients with chronic heart failure. In patients with chronic obstructive pulmonary disease (COPD), pulmonary hypertension (PH) is associated with a poor prognosis. We investigated whether repeated Waon therapy improves PH, cardiac function, exercise tolerance, and the quality of life (QOL) in patients with COPD. METHODS: Consecutive 13 patients with COPD, who met the Global Initiative for Chronic Obstructive Lung Disease criteria and had breathlessness despite receiving conventional treatments, were recruited for this study. They underwent Waon therapy at 60 degrees C in sauna for 15 min following 30 min warmth with blankets outside of the sauna room. This therapy was performed once a day, for 4 weeks. Cardiac function, exercise tolerance, and St. George's Respiratory Questionnaire (SGRQ) were assessed before and 4 weeks after Waon therapy. RESULTS: Right ventricular positive dP/dt at rest elevated significantly from 397 +/- 266 to 512 +/- 320 mmHg/s (p = 0.024) after the therapy. While the PH at rest did not significantly decrease, the PH during exercise decreased significantly from 64 +/- 18 to 51 +/- 13 mmHg (p = 0.028) after Waon therapy. Furthermore, the therapy prolonged the mean exercise time of the constant load of cycle ergometer exercise test from 360 +/- 107 to 392 +/- 97 s (p = 0.032). The total scores of SGRQ improved from 59.7 +/- 16.9 to 55.3 +/- 17.2 (p = 0.002). In addition, no adverse effects were observed related to Waon therapy. CONCLUSIONS: Repeated Waon therapy improved right ventricular positive dP/dt, PH during exercise, exercise tolerance and the QOL in patients with severe COPD.