Effect of attitudes and beliefs on exercise tolerance in chronic bronchitis.

In 50 patients with chronic bronchitis the relation was assessed between exercise tolerance and pulmonary function and psychological factors, including subjective perception of exertion, mood, general psychiatric disturbance, and the attitudes and beliefs held by patients concerning themselves, their illness, and its treatment. Ventilatory capacity was significantly correlated with but a poor predictor of exercise tolerance. Subjective perception of exertion was most closely correlated with exercise tolerance. The distance walked in a 12-minute exercise test was significantly correlated with measurements of mood and with several attitudes and beliefs. Attitudes and beliefs greatly outweighed measurements of mood and ventilatory capacity as components in a multiple regression predicting distance walked in 12 minutes. This method of psychological assessment emphasises the importance of attitudes and beliefs in respiratory disability and may have useful applications in rehabilitation in other chronic diseases.     

Ozone and high ventilation effects on pulmonary function and endurance performance

Ozone (O3) toxicity is potentiated by exercise-induced expired minute ventilation (VE) for a given exposure, which may also impair endurance performance. Ten healthy, well-trained long-distance runners were exposed on six occasions for 1 h to O3 concentrations of 0, 0.20, or 0.35 parts per million (ppm), during exercise simulating either training or competition, with mean VE = 77.5 1 X min -1. Standard pulmonary function tests, subjective symptoms, and periodic observations of exercise ventilatory response and respiratory metabolism were obtained. Statistical analyses revealed no significant exercise mode effect for pulmonary function, but a significant O3 effect for forced vital capacity and expiratory volume at 1 s was observed. Altered exercise ventilatory pattern response was noted, but there was no significant O3 effect on exercise oxygen uptake, heart rate, VE, or alveolar ventilation. Subjective symptoms increased with O3 concentration. Statistically significant pulmonary function impairment observed at 0.20 ppm O3 suggests that endurance athletes may be more susceptible to the effects of a given O3 concentration than normal young adult males as a result of sustained high mean VE incurred during training and competition. Three subjects were unable to complete both the training and competitive simulations at 0.35 ppm O3. Performance decrements appeared to be the result of physiologically induced respiratory discomfort rather than decrements in pulmonary gas exchange and/or oxygen transport and delivery.     

Carbon monoxide and exercise tolerance in chronic bronchitis and emphysema.

The effects of carbon monoxide on exercise tolerance as assessed by the distance walked in 12 minutes were studied in 15 patients with severe chronic bronchitis and emphysema (mean forced expiratory volume in one second 0.56 1, mean forced vital capacity 1.54 1). Each subject walked breathing air and oxygen before and after exposure to sufficient carbon monoxide to raise their venous carboxyhaemoglobin concentration by 9%. There was a significant reduction in the walking distance when the patients breathed air after exposure to carbon monoxide (p less than 0.01), and the significant increase in walking distance seen after exercise when breathing oxygen at 2 1/minute via nasal cannulae was abolished if carbon monoxide has previously been administered. Thus concentrations of carboxyhaemoglobin frequently found in bronchitic patients who smoke may reduce their tolerance of everyday exercise, possibly by interfering with the transport of oxygen to exercising muscles.     

Effects of NO2 alone and in combination with O3 on young men and women

Previous studies of 2 h of exposure to NO2 at high urban atmospheric levels (i.e., 0.50-1.0 ppm), utilizing light-to-moderate exercise for up to 1 h have failed to demonstrate significant pulmonary dysfunction in healthy humans. To test the hypothesis that heavy sustained exercise would elicit pulmonary dysfunction on exposure to 0.60 ppm NO2 and/or enhance the effects of exposure to 0.30 ppm O3, 40 aerobically trained young adults (20 males and 20 females) completed 1 h of continuous exercise at work rates eliciting a mean minute ventilation of 70 and 50 l/min for the males and females, respectively. Exposures to filtered air, 0.60 ppm NO2, 0.30 ppm O3, and 0.60 ppm NO2 plus 0.30 ppm O3 were randomly delivered via an obligatory mouthpiece inhalation system. Treatment effects were assessed by standard pulmonary function tests and exercise ventilatory and subjective symptoms response. Two-way analysis of variance with repeated measures and post hoc analyses revealed a statistically significant (P less than 0.05) effect of O3 on forced expiratory parameters, specific airway resistance, exercise ventilatory response, and reported subjective symptoms of respiratory discomfort. In contrast, no significant effect of NO2 was observed nor was there any significant interaction of NO2 and O3 in combination. There were no significant differences between male and female responses to gas mixture treatments. It was concluded that inhalation of 0.60 ppm NO2 for 1 h while engaged in heavy sustained exercise does not elicit effects evidenced by measurement techniques used in this study nor evoke additive effects beyond those induced by 0.30 ppm O3 in healthy young adults.     

Sensory-mechanical relationships during high-intensity, constant-work-rate exercise in COPD.

During constant-work-rate exercise in chronic obstructive pulmonary disease, dyspnea increases steeply once inspiratory reserve volume (IRV) falls to a critical level that prevents further expansion of tidal volume (Vt). We studied the effects of this mechanical restriction on the quality and intensity of exertional dyspnea and examined the impact of an anticholinergic bronchodilator. In a randomized, double-blind, crossover study, 18 patients with chronic obstructive pulmonary disease (forced expiratory volume in 1 s = 40 +/- 3%predicted; mean +/- SE) inhaled tiotropium 18 mug or placebo once daily for 7-10 days each. Pulmonary function tests and symptom-limited cycle exercise at 75% of each patient's maximal work capacity were performed 2 h after dosing. Dyspnea intensity (Borg scale), operating lung volumes, breathing pattern, and esophageal pressure (n = 11) were measured during exercise. Dynamic hyperinflation reached its maximal value early in exercise and was associated with only mild increases in dyspnea intensity and the effort-displacement ratio, which is defined as the ratio between tidal swings of esophageal pressure (expressed relative to maximum inspiratory pressure) and Vt (expressed relative to predicted vital capacity). After a minimal IRV of 0.5 +/- 0.1 liter was reached, both dyspnea and the effort-displacement ratio rose steeply until an intolerable level was reached. Tiotropium did not alter dyspnea-IRV relationships, but the increase in resting and exercise inspiratory capacity was associated with an improved effort-displacement ratio throughout exercise. Once a critically low IRV was reached during exercise, dyspnea rose with the disparity between respiratory effort and the Vt response. Changes in dyspnea intensity after tiotropium were positively correlated with changes in this index of neuromechanical coupling.     

Ozone inhalation effects consequent to continuous exercise in females: comparison to males

Exposure to ozone (O3) at ambient photochemical smog alert levels has been shown to cause alteration in pulmonary function and exercise response in humans, but there is a paucity of data on females. The initial purpose of the present investigation was to study the effects of O3 inhalation on pulmonary function and selected exercise respiratory metabolism and breathing pattern responses in young adult females. Six female subjects exercised continuously on a bicycle ergometer for 1 h on 10 occasions at one of three intensities, while exposed to 0.0, 0.20, 0.30, or 0.40 ppm O3. Forced expiratory volume and flow rates and residual volume (RV) were measured before and immediately following each protocol. During exercise, expired minute ventilation (VE), respiratory frequency (fR), tidal volume, O2 uptake (VO2), and heart rate (HR) were measured every 10 min. O3 dose-dependent decrements were observed for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), and forced expiratory flow rate during the middle half of FVC, coupled with an increase in RV and altered exercise ventilatory pattern. There was also an increased VE but no significant O3 effect on VO2 or HR. Comparison of the females' responses to those of a group of young adult males (previously studied) at the same total O3 effective dose (i.e., expressed as the simple product of O3 concentration, VE, and exposure time) revealed significantly greater effects on FVC, FEV1.0, and fR for the females. With VE reduced for females as a function of exercise intensity at the same percent of maximum VO2, these differences were considerably attenuated, although not negated.(ABSTRACT TRUNCATED AT 250 WORDS)     

八段锦联合肺功能康复训练对慢性阻塞性肺病稳定期患者肺功能、运动耐力及生活质量的影响

摘要 目的：观察肺功能康复训练联合八段锦对慢性阻塞性肺病（COPD）稳定期患者运动耐力、肺功能及生活质量的影响。方法：选取80例COPD稳定期患者,纳入病例时间：2018年1月~2020年7月,采用随机数字表法分为观察组（肺功能康复训练联合八段锦,40例）、对照组（肺功能康复训练,40例）,干预6个月。对比两组干预前、干预6个月后的肺功能[用力肺活量（FVC）、1秒用力呼气容积（FEV₁）]、运动耐力[6 min步行距离（6MWD）]及生活质量[世界卫生组织生存质量量表简表（WHOQOL-BREF）评分]、症状评分[改良英国医学研究学会呼吸困难量表（mMRC）评分、慢阻肺综合评估测试（CAT）评分]。结果：两组干预6个月后FVC、6MWD、FEV₁均较干预前升高,且观察组高于对照组（P<0.05）。两组干预6个月后WHOQOL-BREF各维度评分较干预前升高,且观察组高于对照组（P<0.05）。干预6个月后, 两组mMRC评分、CAT评分较干预前下降,且观察组低于对照组（P<0.05）。结论：肺功能康复训练联合八段锦干预COPD稳定期患者,可缓解其临床症状,提高肺部适应性,进而改善患者运动耐力及生活质量。     

二十四式简化太极拳联合呼吸功能训练对中老年COPD患者肺功能、运动耐力及心理状态的影响

摘要 目的：探讨二十四式简化太极拳联合呼吸功能训练对中老年慢性阻塞性肺疾病（COPD）患者肺功能、运动耐力及心理状态的影响。方法：选取2019年4月~2020年8月期间我院收治的中老年COPD患者81例,按照信封抽签法分为对照组（40例,给予呼吸功能训练干预）和观察组（41例,给予二十四式简化太极拳联合呼吸功能训练干预）,均干预6个月。对比两组干预前、干预6个月后的肺功能、运动耐力、心理状态及生活质量。结果：两组干预6个月后用力肺活量（FVC）、1 秒用力呼气容积( FEV1)、FEV1/FVC升高,且观察组高于对照组（P<0.05）。两组干预6个月后呼吸症状、疾病影响、活动受限评分降低,且观察组低于对照组（P<0.05）。两组干预6个月后6 min步行试验（6MWT）距离延长,且观察组长于对照组（P<0.05）。两组干预6个月后人际关系、抑郁、偏执、敌对、焦虑、恐惧评分降低,且观察组低于对照组（P<0.05）。结论：中老年COPD患者经二十四式简化太极拳联合呼吸功能训练干预后,肺功能、运动耐力、生活质量及心理状态均得到显著改善,提示该康复训练方案可用于辅助中老年COPD患者的治疗。     

Combined effects of ozone exposure and ambient heat on exercising females

Ten aerobically trained young adult females exercised continuously at 66% of maximum O2 uptake for 1 h while exposed orally to filtered air and 0.15 and 0.30 parts per million (ppm) ozone (O3) in both moderate (24 degrees C) and hot (35 degrees C) ambient conditions. Exposure to 0.30 ppm O3 induced significant impairment in forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), and other pulmonary function variables. Exercise respiratory frequency (fR) increased, whereas tidal volume and alveolar volume (VA) decreased with 0.30 ppm O3 exposure. Significant interactions of O3 and ambient heat were obtained for fR and VA, whereas FVC and FEV1.0 displayed a trend toward an O3-temperature interaction. Although expired ventilation increased, the interactions could not be ascribed to a greater O3 effective dose in the 35 degrees C exposures. However, subjective discomfort increased with both O3 and heat exposure such that three subjects ceased exercise prematurely when O3 and ambient heat were combined. We conclude that accentuation of subjective limitations and certain physiological alterations by ambient heat coinciding with photochemical oxidant episodes is likely to result in more severe impairment of exercise performance, although the mechanisms remain unclear.     

布地格福与布地奈德福莫特罗粉对COPD缓解期患者肺功能、运动耐力的影响对比

摘要 目的：探讨布地格福与布地奈德福莫特罗粉对慢性阻塞性肺疾病（COPD）缓解期患者肺功能、运动耐力的影响。方法：选取2020年1月至2022年12月本院收治的300例COPD缓解期患者,将其随机分为A组（n=150）和B组（n=150）,A组予以布地格福吸入治疗,B组予以布地奈德莫特罗粉吸入治疗。连续治疗3个月后,比较两组疗效及用药安全性;比较两组肺功能、血气水平、运动耐力和生活质量、炎症指标变化。结果：连续治疗3个月后,A组治疗总有效率为96.00 %,高于对照组的90.00 %（P＜0.05）;治疗后两组第1 s用力呼气容积（FEV₁）、FEV₁/用力肺活量、FEV₁占预计值百分数、血氧分压、6 min步行距离较治疗前均有提升,且A组高于B组（P＜0.05）;治疗后两组残气容积/肺总量、二氧化碳分压、白细胞介素-17、基质金属蛋白酶-9、圣乔治呼吸问卷评分较治疗前均有降低,且A组低于B组（P＜0.05）;治疗期间两组均未发生严重的不良反应（P＞0.05）。结论：相较于布地奈德福莫特罗,布地格福对COPD缓解期的治疗效果更佳,能有效减低气道炎症损伤,改善其肺功能及血气水平,提升患者运动耐力及生活质量。     

Relation of pressure and flow of pulmonary circulation in patients with chronic obstructive pulmonary disease

A series of 31 patients with various degrees of chronic obstructive pulmonary disease underwent right heart catheterization using flow-directed thermodilution catheters. Both rest and supine exercise values were obtained. The patients were divided into two groups on the basis of their reduction in forced expiratory volume in 1 s (FEV1). In patients with FEV1 values of greater than or equal to 1,300 ml (group 1), the arterial oxygen partial pressure (PaO2) did not significantly change with exercise, while in patients with FEV1 of less than or equal to 1,200 ml (group 2) PaO2 significantly (p less than 0.05) fell in response to exercise. In group 2, a significant increase of total pulmonary resistance (TPR) with exercise was found (p less than 0.01). Pulmonary vascular resistance (PVR) remained unchanged in both subgroups. It is suggested that the value of PVR for subgroup 2 is artificially low because an important variable, namely pulmonary artery wedge pressure, is influenced by alveolar pressure in patients with an uneven distribution of perfusion and ventilation at pulmonary venous pressures lower than alveolar pressure. The steeper slope of the pressure-flow relationship in these patients is probably due to an increased vascular tone caused by chronic hypoxia at rest and further fall of PaO2 and rise of arterial CO2 partial pressure in response to exercise.     

Effect of aerobic training on forced expiratory airflow in exercising asthmatic humans

Pulmonary function after exercise was evaluated in 22 asthmatic subjects before and after a 36-session training sequence of aerobic exercise. Training did not change pulmonary function values, except for a small increase in maximal voluntary ventilation (P less than 0.02), which was attributed to respiratory muscle training. After aerobic training, both external work at a given heart rate and peak O2 consumption increased by 30 and 15%, respectively. At the same minute ventilation (VE), immediate postexercise forced expiratory airflow was higher after training (P less than 0.02), and reduction in forced expiratory airflow during the first 9 min postexercise was less after training (P less than 0.01). The posttraining airflow response to the pretraining work load was, as expected, less than the pretraining response (P less than 0.02). Although the difference in maximal-to-minimal airflow at the same VE was similar before and after training, the airflow increase accounted for 50% of the response after training compared with 16% of the pretraining response. Furthermore the strong negative correlation (P less than 0.01) between maximal and minimal airflow both pre- and posttraining indicates that exercise-induced bronchospasm (EIB) severity is, in part, determined by the degree of exercise-induced bronchodilation. We conclude that aerobic training significantly increases exercise-induced bronchodilation and diminishes EIB.     

Effects of exercise on young and adult cattle at low and high altitude

Nine calves and nine oxen walked on a treadmill in a climatized low pressure chamber for one hour each day, 2 weeks at 400 m and 4 weeks at 3,500 m. The overall effects of walking were: increases in heart rate, pulmonary arterial pressure, rectal temperature, respiratory rate, blood-pH and lactate/pyruvate ratio. Haemoglobin, haematocrit, blood specific gravity and blood viscosity increased in the oxen but decreased in the calves. Blood lactate and blood pyruvate declined in both age groups, plasma viscosity only in the calves. The exercise effects were more pronounced at 3,500 m than at 400 m as exemplified by the following percentile differences (3,500-400 m): in heart rate 26%, mean pulmonary arterial pressure: 22%, respiratory rate: 11%, blood pH: 0.3%, blood lactate: 39%, blood pyruvate: 56%, haemoglobin: 4%, blood viscosity: 5%. Compared with the calves, the oxen experienced larger increases in heart rate and respiratory rate in response to exercise, suggesting a greater rise in metabolic rate: they also showed a more pronounced respiratory alkalosis. Thus, exercise seems to have strained the oxen more than the calves. In the oxen, there was a training effect as judged by reductions in exercising heart rate, respiratory rate and rectal temperature.     

Effects of ozone exposure on four consecutive days on work performance and VO2max

The effects of 4 consecutive days of 1-h exposure to 0.35 ppm ozone (O3) on maximal O2 uptake (VO2max), performance time, pulmonary function, and subjective symptom responses were studied in eight aerobically trained males. Each subject was first exposed in random order to filtered air (FA) and 0.35 ppm O3 while exercising on a bicycle ergometer for 50 min at a work load eliciting minute ventilation of approximately 60 1/min. A rapidly incremented VO2max test to volitional fatigue was completed within 10 min following each of these exposures, as well as on day 4 of the consecutive daily exposures to O3. Initial exposure to O3 induced the occurrence of subjective symptoms, as well as significant pulmonary function impairment and decrements in maximal exercise performance time (from 253 to 211 s) and VO2max (from 3.85 to 3.62 l/min). Following the fourth consecutive day of exposure to O3, pulmonary function impairment was not significantly different from initial exposure to O3, although subjective symptom severity was significantly reduced. Exercise performance time (239 s) and VO2max (3.79 l/min) on the fourth consecutive daily exposure to O3 were not significantly different from FA values. These data indicate no significant adaptation to initial O3 exposure-induced pulmonary function impairment following four consecutive daily exposures to O3, although reduced subjective symptom severity and enhanced exercise performance time on day 4 suggest an habituation effect. Our results also suggest that O3 adaptation may be a more complex phenomena than identified previously.     

Effect of mild-to-moderate airflow limitation on exercise capacity

To determine the effect of mild-to-moderate airflow limitation on exercise tolerance and end-expiratory lung volume (EELV), we studied 9 control subjects with normal pulmonary function [forced expired volume in 1 s (FEV1) 105% pred; % of forced vital capacity expired in 1 s (FEV1/FVC%) 81] and 12 patients with mild-to-moderate airflow limitation (FEV1 72% pred; FEV1/FVC % 58) during progressive cycle ergometry. Maximal exercise capacity was reduced in patients [69% of pred maximal O2 uptake (VO2max)] compared with controls (104% pred VO2max, P less than 0.01); however, maximal expired minute ventilation-to-maximum voluntary ventilation ratio and maximal heart rate were not significantly different between controls and patients. Overall, there was a close relationship between VO2max and FEV1 (r2 = 0.62). Resting EELV was similar between controls and patients [53% of total lung capacity (TLC)], but at maximal exercise the controls decreased EELV to 45% of TLC (P less than 0.01), whereas the patients increased EELV to 58% of TLC (P less than 0.05). Overall, EELV was significantly correlated to both VO2max (r = -0.71, P less than 0.001) and FEV1 (r = -0.68, P less than 0.001). This relationship suggests a ventilatory influence on exercise capacity; however, the increased EELV and associated pleural pressures could influence cardiovascular function during exercise. We suggest that the increase in EELV should be considered a response reflective of the effect of airflow limitation on the ventilatory response to exercise.     

Ozone inhalation effects in females varying widely in lung size: comparison with males

It has been suggested that lung size accounts for observed gender differences in responsiveness to the same total inhaled dose of O3. To test the hypothesis that lung size is a determinant of magnitude of response within a gender, two groups of 14 healthy young adult females differing significantly in forced vital capacity [FVC; i.e., small-lung group mean = 3.74 liters (range 3.2-4.0) and large-lung group mean = 5.11 liters (range 4.5-6.2] were exposed for 1 h to filtered air (FA) and to 0.18 and 0.30 ppm O3. On each occasion, subjects exercised continuously on a cycle ergometer at a work rate that elicited a mean minute ventilation of approximately 47 l/min. For the small-lung group [mean total lung capacity (TLC) = 4.52 liters] exercise O2 uptake was 67% of maximal O2 uptake (VO2max), and that for the large-lung group (TLC 6.37 liters) was 61% of VO2max. Statistical analysis revealed significant decrements for both groups in FVC, forced expiratory volume in 1 s (FEV1.0), and forced expiratory flow rate in the middle half of FVC on exposure to 0.18 and 0.30 ppm O3. Exercise respiratory frequency increased, and tidal volume decreased significantly in both groups in response to 0.18 and 0.30 ppm O3 exposure. On exposure to 0.30 ppm O3, the number of individual subjective symptoms reported and their severity were significantly greater for both groups than those reported for the FA and 0.18 ppm O3 exposures. Both groups evidenced similar percent changes in pulmonary function and exercise ventilation response, and in subjective symptom response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of reduction mammaplasty on pulmonary function and symptoms of macromastia

A number of studies have documented subjective improvement in somatic and psychological symptoms following breast reduction surgery. Objective data demonstrating improved postoperative function have been more difficult to assess, and particularly with respect to pulmonary function, the results have been contradictory. In this prospective study, patients completed a comprehensive preoperative questionnaire modified from the American Thoracic Society Division of Lung Diseases Epidemiology Standardization Project (1978). This questionnaire noted subjective pulmonary symptoms and pulmonary medical history. In addition, subjective symptoms related to breast size, including back and neck pain and shoulder pain and grooving, and a subjective evaluation of body image, were evaluated. All subjects received preoperative pulmonary function testing, including spirometry, lung volume measurements, and measurement of peak inspiratory and expiratory flow rates and pressures. Eight weeks after breast reduction, a repeat questionnaire and pulmonary function testing were administered. Preoperative and postoperative pulmonary function values were compared using Cochran-Mantel-Haenszel tests, and correlations were tested between changes in pulmonary function test values and subjective symptom improvement. Forty-four patients underwent an average of 2228-g bilateral reduction. All of these patients had their surgical procedures preauthorized as medically necessary by their insurance carriers. All subjective parameters examined were statistically significantly improved following breast reduction (p < 0.001). Of the 17 patients with preoperative complaints of shortness of breath, all noted significant improvement following breast reduction surgery (p < 0.001). Of the objective pulmonary criteria evaluated, inspiratory capacity, peak expiratory flow rate, and maximal voluntary ventilation showed a statistically significant improvement following surgery (p < 0.05). These changes correlated with body mass index; the greater the index, the greater the change in maximal voluntary ventilation and peak expiratory flow rate. Smokers in this group had the largest change in maximal voluntary ventilation (p < 0.008). No correlation could be found between preoperative pulmonary symptoms, a single subjective symptom, or grams of breast weight reduction and changes in pulmonary function tests. The results show that pulmonary parameters, related primarily to work of breathing (inspiratory capacity, maximal voluntary ventilation, peak expiratory flow rate), were statistically improved following breast reduction surgery, and these changes correlated with body mass index.     

Dose response relation to oral theophylline in severe chronic obstructive airways disease.

OBJECTIVE--To evaluate measurement of the trapped gas volume as a measure of respiratory function in patients with chronic obstructive airways disease and their response to treatment with theophylline. DESIGN--Patients able to produce consistent results on testing of respiratory function spent two weeks having dosage of theophylline adjusted to give individual pharmacokinetic data. This was followed by random assignment to four consecutive two month treatment periods--placebo and low, medium, and high dose, as assessed by serum concentrations of theophylline. Respiratory function and exercise performance was assessed at the end of each two month period. SETTING--Chest unit in district hospital. PATIENTS--Thirty eight patients with chronic bronchitis and moderate to severe chronic obstruction to airflow were recruited; 33 aged 53-73 years completed the study. INTERVENTIONS--Dosage of oral theophylline increased during two week optimisation period to 800 mg daily unless toxicity was predicted, when 400 mg was given. Targets for the steady state serum theophylline concentrations were 5-10 mg/l in the low dose period, 10-15 mg/l in the medium dose, and 15-20 mg/l in the high dose period. ENDPOINTS--Respiratory function as measured by forced expiratory volume in one second, forced vital capacity, peak expiratory flow rate, slow vital capacity, and static lung volumes using helium dilution and body plethysmography from which trapped gas volume was derived. Exercise performance assessed by six minute walking test and diary cards using visual analogue scale. MEASUREMENTS AND MAIN RESULTS--The forced expiratory volume in one second, forced vital capacity, and peak expiratory flow rate changed only slightly (about 13%) over the range of doses. There was a linear dose dependent fall of trapped gas volume from 1.84 l (SE 0.157) to 1.42 l (0.152), 1.05 l (0.128), and 0.67 l (0.102) during the placebo and low, medium, and high dose treatment periods. Mean walking distance increased by up to 55.6 m (20%). There was a modest improvement in dyspnoea as the dose of theophylline was increased. Side effects were mostly minor but they became more frequent as the dose was increased. CONCLUSION--The fall in trapped gas volume may reflect an improvement in peripheral ventilation (associated with treatment with theophylline) which is less apparent in the more common tests of lung function used in patients with chronic obstructive airways disease.     

Are "pink puffers" more breathless than "blue bloaters"?

Breathlessness, disability, and exercise tolerance were assessed in 26 patients with severe chronic airflow limitation (forced expiratory volume in one second (FEV1) less than or equal to 1 litre) divided into two groups--15 patients who were normocapnic (pressure of arterial carbon dioxide (Paco2) less than 5.5 kPa (less than 41.4 mm Hg)), and 11 patients who were hypercapnic (Paco2 greater than 6 kPa (greater than than 45.1 mm Hg)). The two groups were well matched for spirometric values (FEV1 0.59 1 and 0.62 1, respectively). All of the hypercapnic patients could improve blood gas tensions towards normal by hyperventilation. There were no significant differences in visual analogue scores of breathlessness during treadmill exercise, disability (oxygen-cost diagram, dyspnoea grade), or exercise tolerance (six-minute walk, maximal consumption of oxygen during bicycle ergometry, distance walked to exhaustion in progressive treadmill test). The findings show that the "fight" to maintain normal blood gas tensions in the face of severe airflow limitation does not have an appreciable cost in terms of disability.     

O.35 ppm O3 exposure induces hyperresponsiveness on 24-h reexposure to 0.20 ppm O3

Pulmonary function hyperresponsiveness, defined as enhanced response on reexposure to O3, compared with initial O3 exposure, has been previously noted in consecutive day exposures to high ambient O3 concentrations (i.e., 0.32-0.42 ppm). Effects of consecutive-day exposure to lower O3 concentrations (0.20-0.25 ppm) have yielded equivocal results. To examine the occurrence of hyperresponsiveness at two levels of O3 exposure, 15 aerobically trained males completed seven 1-h exposures of continuous exercise at work rates eliciting a mean minute ventilation of 60 1/min. Three sets of consecutive-day exposures, involving day 1/day 2 exposures to 0.20/0.20 ppm O3, 0.35/0.20 ppm O3, and 0.35/0.35 ppm O3, were randomly delivered via an obligatory mouthpiece inhalation system. A filtered-air exposure was randomly placed 24 h before one of the three sets. Treatment effects were assessed by standard pulmonary function tests, exercise ventilatory pattern (i.e., respiratory frequency, f; and tidal volume, VT) changes and subjective symptom (SS) response. Initial O3 exposures to 0.35 and 0.20 ppm had a statistically significant effect, compared with filtered air, on all measurements. On reexposure to 0.35 ppm O3 24 h after an initial 0.35 ppm O3 exposure, significant hyperresponsiveness was demonstrated for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), f, VT, and total SS score. Exposure to 0.20 ppm O3 24 h after 0.35 ppm O3 exposure, however, resulted in significantly enhanced responses (compared with initial 0.20 ppm O3 exposure) only for FEV1, f, and VT.(ABSTRACT TRUNCATED AT 250 WORDS)