Resistive breathing training in patients with chronic obstructive pulmonary disease

In order to investigate the effect of resistive breathing training on ventilatory muscular endurance, we examined the maximal sustained ventilatory capacity in ten patients with chronic obstructive pulmonary disease (COPD) before and after a six-week program of resistive breathing training. In addition, we investigated the effect of altered breathing strategy on resistive breathing performance. The patients performed two 15-minute sessions of resistive breathing daily for six weeks using an inspiratory resistive device (Pflex). Before and after the training, we found no significant change in spirometric data, pulmonary volumes, maximal inspiratory pressure, and maximal expiratory pressure. Of the ten patients, seven failed to show an improvement in their performance of resistive breathing. Furthermore, the maximal sustained ventilatory capacity was unchanged after the resistive breathing training. After the completion of the training program, seven of the patients participated in an additional experiment in which they were instructed to take long slow inspirations while breathing through the resistive device. With this change in breathing pattern, five of the seven were able to improve their performance of resistive breathing. Analysis of the breathing strategy showed that a reduction in the peak mouth pressure, breathing frequency, and external resistive work with a longer inspiratory time was beneficial. We conclude that neither resistive breathing performance nor ventilatory muscular endurance, as measured by sustained hyperpnea, is improved by resistive breathing training performed according to the current instructions with the resistive device, and alterations in breathing strategy have a profound effect on the performance of resistive breathing. The lack of details of breathing strategy in previous studies of resistive breathing makes it difficult to determine if previously demonstrated improvements were due to a real enhancement of ventilatory muscular performance or merely secondary to a different strategy.     

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.     

Efficacy of diaphragmatic breathing in patients with chronic obstructive pulmonary disease

This study investigated the effects of diaphragmatic breathing (DB) on ventilation and breathing pattern, seeking to identify predictors of its efficacy in patients with chronic obstructive pulmonary disease (COPD). Twenty-nine patients with moderate and severe COPD were monitored using respiratory inductance plethysmography and metabolic gas analysis. After 4 minutes of natural breathing, subjects completed 2 minutes of DB followed by 4 minutes of natural breathing. Dyspnea was measured using a visual analogue scale. Diaphragmatic mobility was assessed using chest radiography. DB was associated with a significant increase in tidal volume and reduction in breathing frequency, leading to higher ventilation and oxygen saturation, with a reduction in dead space ventilation and ventilatory equivalent for carbon dioxide. A total of 10 subjects with moderate (5) and severe (5) COPD performed DB with asynchronous thoracoabdominal motion, worsening the dyspnea, and decreasing the gain of tidal volume. Diaphragmatic mobility, inspiratory muscular strength, lower scores for dyspnea and hypoxemia as well as coordinated thoracoabdominal motion are associated with effective DB. In patients with COPD, DB can improve breathing pattern and ventilatory efficiency without causing dyspnea in patients whose respiratory muscular system is preserved.     

Diaphragm length during tidal breathing in patients with chronic obstructive pulmonary disease

Diaphragm function is compromised in severe chronic obstructive pulmonary disease (COPD) by hyperinflation, but its ability to shorten and contribute to tidal volume is uncertain. We estimated coronal diaphragm length by measuring zone of apposition length with ultrasound and rib cage diameters with magnetometers, in 10 male patients with severe COPD and 10 age- and sex-matched control subjects. Diaphragm length was 20% shorter in patients at residual volume (413 and 536 mm in patients and control subjects, respectively) and FRC (381 and 456 mm, respectively), but was not different at total lung capacity (312 and 336 mm, respectively). Zone of apposition length was reduced 50% at residual volume and FRC in patients, but was larger at a given absolute lung volume than in control subjects. There were no differences in tidal volume (0.8 L), tidal changes in zone of apposition length (20 mm) and diaphragm length (38 and 42 mm), and tidal volume displaced by the diaphragm (0.6 L), even though mean FRC in patients was similar to predicted total lung capacity. Although the diaphragm is shorter at FRC in patients with COPD, its motion and change in length during tidal breathing is similar to that in control subjects.     

Augmented heart rate response to hypoxia in patients with chronic obstructive pulmonary disease.

Effects of acute, progressive isocapnic hypoxia on heart rate (HR) and ventilation were determined in 31 patients with chronic obstructive pulmonary disease (COPD) and in 24 normal control subjects. There was an inverse linear relationship between heart rate and SaO2 in each subject. The slope factor (delta HR/delta SaO2) obtained from the regression line was significantly higher in the patients with COPD than in the normal control subjects (0.888 +/- 0.309 SD beats/min/% fall in SaO2 versus 0.693 +/- 0.287; p less than 0.05), whereas the ventilatory response (delta VE/delta SaO2) was not significantly different between the two groups. To elucidate factors responsible for the augmented heart rate response to hypoxia in the patients with COPD, we examined the relationships of delta HR/delta SaO2 with age, physical characteristics, pulmonary function data, and arterial blood gas data in all the subjects. A weak but significant relationship was found only between delta HR/delta SaO2 and FEV1/VC, %FEV1, RV/TLC, and %RV. Because the HR response to hypoxia correlates only with parameters that reflect the grade of airway obstruction, we believe that the enhanced HR response seen in patients with COPD is a result of the disease process in the airway and tissue, although the precise mechanism was not specified in this study.     

Failure of resistive breathing training to improve pulmonary function tests in patients with chronic obstructive pulmonary disease

The effects on pulmonary function tests and exercise tolerance of resistive breathing training (RBT) were assessed in 16 subjects with stable chronic obstructive pulmonary disease (COPD) who had received no benefit from previous programs of breathing retraining (BR) and medical therapy (MT). 16 male patients with mild degree stable COPD underwent detailed evaluation of pulmonary function tests, blood gas analysis and exercise tolerance test before and after a monthly program of RBT. The patients had received no physiological effects from previous monthly programs of BR and MT. No change in pulmonary function tests, blood gas analysis and exercise tolerance test was observed after RBT. Only maximal static expiratory pressure increased significantly after RBT. We conclude that RBT does not improve pulmonary function tests in subjects who received no physiological benefit from BR.     

Work of breathing in patients with chronic obstructive pulmonary disease in acute respiratory failure

In 11 spontaneously breathing patients with chronic obstructive pulmonary disease (COPD) in acute ventilatory failure, we measured the total inspiratory (WItot) and total resistive (WI + Eres) work rate of breathing, together with lung mechanics (dynamic pulmonary elastance and inspiratory and expiratory pulmonary flow resistance). All variables were markedly increased compared with those in normal subjects. No significant correlation was found between WItot and WI + Eres with lung mechanics data. However, when WItot and WI + Eres were expressed per liter of ventilation, a significant positive correlation was found with all lung mechanics data. These results indicate that although in patients acutely ill with COPD, work rate and work per liter of ventilation are increased, only the latter is related to the severity of pulmonary mechanical impairment, and it could be used as one of the criteria for extubation. In addition, our results indicate that at end-expiration the alveolar pressure was positive (range, 6 to 13 cm H2O) in all patients (intrinsic PEEP), a fact that must necessarily affect hemodynamics; furthermore, it imposes an extra burden on the inspiratory muscles.     

Systemic inflammatory response to exhaustive exercise in patients with chronic obstructive pulmonary disease

Systemic inflammation may be present in patients with chronic obstructive pulmonary disease (COPD). Exercise is known to elicit an inflammatory response. We hypothesized that the systemic inflammatory response to exercise might be exaggerated in COPD patients compared to healthy subjects. Sixteen COPD patients and 11 healthy subjects performed a maximal incremental bicycle test. Before and at maximal exercise arterial blood samples were taken to determine circulating catecholamines, (subsets of) leukocytes, acute phase proteins, creatine kinase and myoglobin. At rest, increased levels of norepinephrine and systemic inflammation were present in COPD. The response of catecholamines to exercise was lower in COPD patients (P<0.01), which in part was due to the lower maximal exercise capacity of these patients (P<0.01). Exercise-induced leukocytosis showed similar responses in both groups, but occurred at higher levels in COPD. Although patients had increased levels of CRP at rest (P<0.001), exercise did not affect acute phase proteins. No systemic signs of muscle damage were found. The present study shows that COPD patients are exposed to systemic inflammation that is intensified by exhaustive exercise. The inflammatory response in COPD is not exaggerated compared to healthy subjects but occurs at a higher level and is observed at lower external workload.     

Control of breathing in chronic obstructive pulmonary disease patients at rest and after beta-2 agonist inhalation.

Ventilatory function tests, ventilatory cycle analysis, mouth occlusion pressure (P0.1) and effective inspiratory impedance (P0.1/Vt/Ti) were measured in 11 healthy subjects and in 26 patients with chronic obstructive pulmonary disease (COPD). In COPD patients these measurements were repeated 20 min after inhalation of 400 micrograms of fenoterol. In patients we observed an increase of mean inspiratory flow (Vt/Ti), and a decrease of inspiratory time (Ti) and inspiratory duty cycle (Ti/Ttot). P0.1 and effective inspiratory impedance were significantly increased. Moreover, we found a direct correlation between forced expiratory volume in 1 s (FEV1) and ventilatory cycle components (Ti/Ttot, Ti) and an indirect correlation between FEV1 and Vt/Ti.P0.1 was directly correlated with Vt/Ti and indirectly correlated with ventilatory cycle components. These observations lead us to speculate on the possible role of two opposite mechanisms acting on the control of breathing of COPD patients. While the 'intensity' component of the ventilatory cycle would be set to maintain the tidal volume at a constant level, the 'timing' component would act in order to prevent inspiratory muscle fatigue. Furthermore, in patients responsive to beta 2-agonist drugs, fenoterol inhalation would act in synergy with the timing component of ventilatory cycle, lowering P0.1 and the effective inspiratory impedance.     

慢性阻塞性肺疾病患者睡眠呼吸紊乱类型及其与呼吸中枢反应性的关系

目的分析重叠综合征[慢性阻塞性肺疾病（COPD）合并睡眠呼吸暂停低通气综合征（SAHS）]患者睡眠呼吸紊乱的特点，并探讨其与呼吸中枢反应性的关系。方法对300例稳定期COPD患者经问卷、Epworth嗜睡量表及家庭血氧饱和度监测，对氧减饱和指数〉5次／h或嗜睡评分≥10分的患者进行多导生理记录仪睡眠呼吸监测，其中呼吸暂停低通气指数（AHI）≥10次／h的患者有79例（重叠综合征组）。选择年龄、性别及体重指数与其相匹配的118例单纯SAHS患者（SAHS组），对比分析其睡眠呼吸紊乱的特点。另外测定重叠综合征组22例患者的呼吸中枢高CO2反应性和低氧反应性，并与300例COPD患者中17例和SAILS组中17例的相应检测结果进行比较。结果40％（32／79）的重叠综合征患者在睡眠过程中出现延续时间〉1min的持续肺泡通气不足，但单纯SAHS患者此种现象很少见。重叠综合征组的低通气指数占AHI百分比[（69±30）％]、总低通气时间占总睡眠时间百分比[（15±12）％]均较单纯SAHS组[（52±31）％、（12±10）％]明显增高。重叠综合征患者在清醒状态下的△呼气流量／△动脉血氧饱和度[（-0．11±0．05）L·min^-1·％^-1]和△呼气流量／△动脉血二氧化碳分压[（1．1±0．8）L·min^-1·mmHg^-1（1mmHg=0．133kPa）]均明显低于单纯SAHS患者[（-0．35±0．24）L·min^-1·％^-1和（1．6±0．8）L·min^-1·mmHg^-1]。结论重叠综合征患者的睡眠呼吸紊乱模式以低通气为主，其清醒时呼吸中枢的低氧反应性降低。     

Alteration in breathing pattern with progression of chronic obstructive pulmonary disease

We examined the relationship between breathing pattern and severity of disease in patients with chronic obstructive pulmonary disease (COPD). Resting breathing pattern was recorded for 45 min using the respiratory inductance plethysmograph (RIP) in 22 patients with stable COPD. Six subjects (moderate group) had FEV1 25 to 50% predicted, 8 subjects (severe group) had FEV1 less than 25% predicted, and 8 subjects (respiratory failure group) had FEV1 less than 25% predicted and were hypoxemic. Seven of the subjects with respiratory failure were also hypercapnic. Subjects with respiratory failure were studied with and without supplemental O2. All subjects were studied in the seated position. There were no significant differences in breathing pattern between the moderate and severe groups. Tidal volume (VT) was 120 ml lower in the severe group, but breathing frequency (f) was slightly elevated, allowing minute ventilation (VI) to be maintained. The respiratory failure group demonstrated a significant decrease in VT compared with that in the moderate group and a significant decrease in VT/TI as compared with both moderate and severe groups; TI was unchanged in subjects with respiratory failure, and, as f did not increase significantly, VI was decreased. Acute relief of hypoxemia had no effect on breathing pattern in respiratory failure. Variability was assessed by comparing the coefficients of variation for each timing component. There was no difference in intraindividual variability of breathing pattern between all groups. These results suggest that changes in ventilatory control as reflected by breathing pattern are to some extent independent of mechanical abnormalities.     

Nocturnal pulmonary hypertension in patients with chronic obstructive pulmonary disease.

Oxygen desaturation occurs during sleep in some patients with COPD. To investigate the effects of these hypoxemic episodes on the pulmonary vasculature, we studied four patients with our routine polysomnographic techniques and simultaneously recorded pulmonary artery pressure. In all four subjects, nocturnal episodes of desaturation were accompanied by elevations in the pulmonary artery pressure. Low flow oxygen abolished the drops in arterial oxygen saturation (but not the breathing abnormalities) and no elevations in the PA pressure were observed. We postulate that in some COPD patients these initially transient events may lead to sustained pulmonary hypertension and cor pulmonale. Nocturnal oxygen therapy may be indicated in more patients than previously suspected and may prevent the development of cor pulmonale.     

Invasive pulmonary aspergillosis in patients with chronic obstructive pulmonary disease.

Aspergillus spp. cultured in specimens from the airways of chronic obstructive pulmonary disease (COPD) patients are frequently considered as a contaminant. However, growing evidence suggests that severe COPD patients are at higher risk of developing invasive pulmonary aspergillosis (IPA), although IPA incidence in this population is poorly documented. Some data report that COPD is the underlying disease in 1% of patients with IPA. Definitive diagnosis of IPA in COPD patients is often difficult as tissue samples are rarely obtained before death. Diagnosis is therefore usually based on a combination of clinical features, radiological findings (mostly thoracic computed tomography scans), microbiological results and, sometimes, serological information. Of 56 patients with IPA reported in the literature, 43 (77%) were receiving corticosteroids on admission to hospital. Breathlessness was always a feature of disease and excess wheezing was present in 79% of patients. Fever (>38 degrees C) was present in only 38.5%. Chest pain and haemoptysis were uncommon. Six out of 33 (18%) patients had tracheobronchitis observed during bronchoscopy. The median delay between symptoms and diagnosis was 8.5 days. The mortality rate was high: 53 out of 56 (95%) patients died despite invasive ventilation and antifungal treatment in 43 (77%) of them. In chronic obstructive pulmonary disease patients, invasive pulmonary aspergillosis currently carries a very poor prognosis. Outcome could perhaps be improved by more rapid diagnosis and prompt therapy with voriconazole.     

Effect of theophylline on sleep and sleep-disordered breathing in patients with chronic obstructive pulmonary disease

To investigate the effect of theophylline on sleep and sleep-disordered breathing in patients with chronic obstructive pulmonary disease (COPD), we studied 12 male nonhypercapnic subjects with a mean +/- SEM age of 62.8 +/- 2.5 yr and a FEV1 of 1.36 +/- 0.11 L using a randomized double-blind crossover protocol. Sustained-action theophylline (250 mg three times or four times a day) or placebo was administered for 2 days, and the alternate drug was administered on the following 2 days. Sleep studies were performed on Nights 2 and 4 with spirometry at 9:00P.M. and 7:00A.M. Two puffs of metaproterenol or albuterol were administered at 10:00P.M. on both study nights. A theophylline level, drawn at bedtime (10:00 to 11:00P.M.), was 14.2 +/- 0.78 micrograms/ml on the theophylline nights and less than 2 on placebo nights. The morning FEV1 was significantly better during theophylline administration (1.27 +/- 0.12 versus 1.00 +/- 0.11 L, p less than 0.001). The mean arterial oxygen saturation (SaO2) and transcutaneous carbon dioxide pressure (PCO2) were also better during NREM sleep on theophylline nights. Neither the mean SaO2 and transcutaneous PCO2 during REM sleep nor the apnea plus hypopnea index (events per hour of sleep) differed between placebo and theophylline nights. Theophylline administration did not impair the amount or architecture of sleep as neither total sleep time nor the fraction of time spent in Stages 1, 2, and 3/4 and REM differed between the two regimens. The number of arousals per hour of sleep was slightly less on theophylline nights (19.9 +/- 1.7 versus 24.9 +/- 2.7, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Course of pulmonary hemodynamics in patients with chronic obstructive pulmonary disease.

Eighty-five patients with chronic obstructive pulmonary disease, mainly chronic bronchitis (71 patients), who had arterial hypoxemia and moderate to severe obstruction of the airways underwent at least two right cardiac catheterizations in a clinical steady state, with a delay of three years or more between the first and the last catheterization. The average delay was 60 +/- 19 months (range, 36 to 119 months). Patients were regularly examined (quarterly clinical and functional checkups). The changes in pulmonary hemodynamic data were small. In the group of 53 patients with an initial mean pulmonary arterial pressure of 20 mm Hg or less, this pressure varied from 15.4 +/- 3.1 to 18.3 +/- 6.6 mm Hg (P less than 0.001); in the group of 32 patients with an initial mean pulmonary arterial pressure greater than 20 mm Hg, this pressure varied from 27.7 +/- 6.0 to 31.0 +/- 9.3 mm Hg (P less than 0.05). The mean pulmonary arterial pressure increased by 5 mm Hg or more in only 28 patients. In these patients with hemodynamic "worsening," the final arterial oxygen pressure (PaO2) was lower and the final arterial carbon dioxide tension was higher than in the remaining patients. A significant negative correlation (r = -0.39; P less than 0.001) was observed between changes in PaO2 and mean pulmonary arterial pressure. There was a generally good agreement between the course of pulmonary hemodynamics (mean pulmonary arterial pressure), on the one hand, and the clinical, radiologic (transverse diameter of the heart), and electrocardiographic evolution, on the other hand. In the 33 patients who died, a relatively long survival was observed after the first episode of right-sided heart failure or after ascertaining pulmonary hypertension.     

Factors associated with improvement in breathing capacity during exercise in patients with chronic obstructive pulmonary disease

OBJECTIVES: The aim of this study was to explore the relationship between resting pulmonary function indices and the ratio of minute ventilation at peak exercise to the maximal voluntary ventilation (VEmax/MVV) and to determine whether an improvement in breathing capacity during exercise (i.e. VEmax/MVV > 1) is associated with greater exercise capacity in patients with COPD. METHODOLOGY: The results of pulmonary function tests and incremental, symptom-limited cardiopulmonary exercise testing in 84 patients with predominantly moderate to severe COPD were reviewed. Multiple linear regression analysis was applied to determine the relationship of VEmax/MVV with selected independent variables at rest. Multiple logistic regression was used to determine significant predictors of VEmax/MVV 1. RESULTS: FEV1/FVC and inspiratory capacity (IC) were the only variables among resting pulmonary function indices that were significant independent determinants of VEmax/MVV and the stepwise analysis generated the following equation: VEmax/MVV = (-1.05E-02 x FEV1/FVC) + (0.15 x IC) + 1.28; r= 0.701, P < 0.001. Using multiple logistic regression with VEmax/MVV 1 as a dependent categorical variable, FEV1/FVC was the only significant predictor among resting pulmonary indices of a VEmax/MVV ratio of > 1 (Odds ratio 0.93, 95%CI 0.89, 0.97). There was a significant association between VEmax/MVV and peak oxygen uptake (VO2max) after adjusting for FEV1 (r = 0.66, P < 0.001). If the categorical variable of VEmax/MVV ( 1) was used instead of a continuous variable, a significant association with VO2max remained after adjusting for FEV1 (r = 0.60, P < 0.001). CONCLUSIONS: Among resting pulmonary function indices, the FEV1/FVC ratio is the best determinant of an improvement in breathing capacity during exercise in COPD patients. After adjusting for FEV1, an improvement in breathing capacity during exercise is associated with significantly higher exercise capacity.