Physical activity and health: COPD - Essay Example

?Physical Activity and Health: COPD Introduction It is a well known fact that health is influenced by physical activity. While appropriate physical activity is essential for prevention of certain diseases like diabetes, hypertension and ischemic heart disease, it is also essential in the management and prevention of progression of certain diseases like chronic obstructive pulmonary disease (Sharma, 2006). Chronic obstructive pulmonary disease or COPD is a devastating medical illness which causes a great degree of human suffering (Sharma, 2006). It is not only a major health issue but also a significant source of economic (Sullivan et al, 2000) and social burden (Fromer and Cooper, 2008). The condition is frequently under diagnosed contributing to increased mortality and morbidity. It cannot be cured; however, appropriate and timely treatment can reduce symptoms, increase the quality of life and decrease mortality and morbidity (GOLD, 2008). The critical strategy for prevention of frequent and distressing exacerbations of COPD is appropriate physical activity and physical therapy. The role of physical activity in improving the health of patients with COPD will be discussed in this essay. An overview of the disease, diagnosis and management will be included in the essay to enhance the understanding of the topic. COPD COPD is defined as "a disease state characterized by the presence of airflow obstruction due to chronic bronchitis or emphysema" (Sharma, 200; pg.1). Clinically, chronic bronchitis is defined as the presence of chronic cough with no other etiology and which is productive for at least 3 months during each of the two consecutive years. Emphysema is damage of the air spaces distal to the terminal bronchioles, the damage being irreversible, abnormal and associated with destruction of the air space walls with no obvious fibrosis (Fromer and Cooper, 2008). The global prevalence of COPD is about 7.5% of which 6.4% is due to chronic bronchitis and only 1.8% due to emphysema (Sharma, 2006). In adults above 40 years of age, the prevalence is estimated to be about 9-10% (Sharma, 2006). Men are most commonly affected by this disease (Sharma, 2006). However, the incidence in women is increasing due to increased smoking (Sharma, 2006). COPD is associated with certain mortality and morbidity. The most common cause of COPD is cigarette smoking (Silvermann and Speizer, 1996). This condition affects about 15% of cigarette smokers (NICE, 2004). Other risk factors for the development of COPD are air pollution especially due to solid cooking fuels, presence of airway hyperresponsiveness (Sharma, 2006). The characteristic pathophysiological changes in COPD are seen in the central airways, the peripheral airways and also the lung parenchyma (Thurlbeck, 1990). Diverse mechanisms are implicated in the pathophysiology of COPD (Thurlbeck, 1990). Primary offenders like oxidative stress due to free radicals from cigarette smoke and oxidants from phagocytes and polymorphonuclear leukocytes trigger the release of certain enzymes like leukocyte elastase in such proportions that they cannot be counteracted effectively by anti-proteases, resulting in destruction of the lung tissues (Thurlbeck, 1990) leading to necrosis or apoptosis of the lung tissue. Due to these mechanisms, certain pathological changes occur in the airways and the lung tissue like inflammation and globlet cell hyperplasia in chronic bronchitis and loss of elastic recoil in emphysema (Thurlbeck, 1990). Other changes include ciliary abnormalities, airway smooth muscle hyperplasia, bronchial wall thickening and sometimes atrophy (Sharma, 2006). These pathophysiological changes contribute to airway flow obstruction, airway hyperresponsiveness and mucus accumulation leading to poor ventilation and oxygenation, breathlessness, cough and infection. A patient may have either emphysema or chronic bronchitis or both. The clinical presentation depends on which pathology is more dominant. When emphysema dominates, features due to loss of elastic recoil is more obvious than bronchiolar disease and when chronic bronchitis dominates, bronchiolar abnormalities contribute to the lung function deficits. Airflow obstruction in emphysema is not reversible at all. However, in chronic bronchitis, the obstruction is due to inflammation and hence is partially reversible (Sharma, 2006). The most common clinical presentation of COPD is productive cough or acute chest infection. However, as the disease progresses, breathlessness ensues and it becomes the most predominant symptom. Along with breathlessness easy fatigability and exercise intolerance also develop making the life of the patient miserable. Breathlessness occurs because of the poor oxygenation and ventilation occurring mainly due to airflow obstruction and partly due to impaired mucus clearance. The degree of breathlessness can vary and it can be measured using The Medical Research Council (MRC) Dyspnea Scale (NICE, 2004). Some patients may present with wheezing, especially during exacerbations and exertion. As the disease progresses, the frequency of exacerbations increases, cyanosis develops and right heart failure may ensue which further worsens breathlessness (Sharma, 2006). The diagnosis of COPD is mainly on the basis of clinical presentation and exclusion of other causes of cough and breathlessness. According to NICE (2004), "diagnosis of COPD should be considered in patients over the age of 35 who have a risk factor (generally smoking) and who present with exertional breathlessness, chronic cough, regular sputum production, frequent winter ‘bronchitis’ or wheeze." Complete blood picture, chest X-ray and body-mass index are evaluated in all patients soon after the establishment of the diagnosis. Pulmonary functions tests are important because they help in the assessment of the severity of lung pathology and also in monitoring response to treatment. The most common index of obstruction of air flow is FEV1 (Fromer and Cooper, 2008). NICE (2004) recommends confirmation of airflow obstruction by spirometry in all patients with COPD. Serial domiciliary peak flow measurements are useful to rule out asthma (Fromer and Cooper, 2008). ECG and ECHO are useful in advanced stages to assess the cardiac status (NICE, 2004). Assessment of cardiac status is essential not only to institute proper treatment but also to set limits for exercise training and other physical therapies. Before starting treatment in COPD, the severity of the disease must be estimated. Since COPD is heterogeneous, there is no single measure which can ascertain the severity of the condition in any patient. However, assessment of severity is important for deciding treatment. The assessment can be made using 3 important aspects which include degree of airflow obstruction, frequency of exacerbations and also certain prognostic factors. The severity of airflow obstruction can be assessed based on the reduction in FEV1. The main prognostic factors are FEV1, MRC scale of breathlessness, exercise capacity, BMI, etc (NICE, 2004). The main goals of treatment of COPD are symptom relief, amelioration of disease progression, increase in exercise tolerance, improvements in health status, prevention of exacerbations and decrease in the risk of death due to COPD (Fromer and Cooper, 2008). There is no cure for COPD. However, the symptoms can be controlled effectively by prompt treatment and diligent follow-up. The first and foremost step in the management of COPD is smoking cessation. Smoking history along with pack years smoked should be elicited and documented in the records of every COPD patient. Every COPD patient must be encouraged to give up smoking. Appropriate support programs and if necessary nicotine replacement therapy should be instituted to bring about cessation of smoking (NICE, 2004). Cessation of smoking prevents further progression of the disease, decreases exacerbations and thus decreases symptoms including breathlessness. The next step in treatment is aimed at reducing the severity of breathlessness and also in decreasing cough. This is done by either pharmacotherapy or physiotherapy or a combination of both. Most experts use a combination of medicines and physical therapy to decrease breathlessness (Sharma, 2006). Research has shown that combination therapy with physical therapy and drug therapy is more effective than only drug-therapy in the management of breathlessness in COPD (Cambach et al, 1997). Medical therapy involves usage of drugs like bronchodilators, steroids and other drugs. The bronchodilators which are useful in COPD are anticholinergics, methylxanthines and beta-2 adrenergic receptors (Fromer and Cooper, 2008). The initial empirical treatment for relief of breathlessness and limitation of exercise should be short-acting bronchodilators. When the patient starts, the effectiveness of the medications should be evaluated based on improvement in exercise capacity, day-to-day activities and the rapidity of symptom relief. In case there is no proper response to these medicines, then either long-acting bronchodilators or a combination of short-acting anticholinergic should be switched over to. In patients who have 2 or more exacerbations in one year, long-acting bronchodilators must be the first line of treatment for breathlessness (NICE, 2004). Oral Corticosteroids have a role during exacerbations. Inhaled corticosteroids are prescribed in those with an FEV1 of 50% or less than 50% of predicted and also in those who are suffering from more than 1 exacerbation in a year which requires oral corticosteroids or antibiotics (NICE, 2004). Combination therapies should be started if patients continue to be breathless when on monotherapy. Some of the effective combinations are beta2-agonist and anticholinergic, beta2 agonist and theophylline, (NICE, 2004). Mucolytics like N-acetyl cysteine can decrease the number of exacerbations (Poole and Black, 2001) and thus decrease breathlessness. Cough syrups have no role in the management of breathlessness in COPD (ATS, 2005). Pulmonary rehabilitation in COPD In most COPD patients with breathlessness, pulmonary rehabilitation programme is advocated. Pulmonary rehabilitation is defined as “a multidisciplinary programme of care for patients with chronic respiratory impairment that is individually tailored and designed to optimize physical and social performance and autonomy” (ATS, 1999). This program should be offered to all patients with breathlessness of grade 3 or above but are not suffering from unstable angina, recent attack of myocardial infarction or inability to walk (NICE, 2004). The program must incorporate disease education, physical training, nutritional intervention, psychological support and behavioural therapy. Pulmonary rehabilitation program improves the quality of life of the patient, increases exertional and exercise tolerance, decreases breathlessness, increases autonomy and coping skills, decreases exacerbations and prevents complications (Brooks et al, 2002). Pulmonary rehabilitation plays an important role in the management of COPD. Research has shown that comprehensive pulmonary management significantly improves exercise performance and decreases the amount of breathlessness. Ries et al (1995) evaluated the effects of comprehensive pulmonary rehabilitation programmes in COPD patients and opined that these interventions significantly decrease the symptoms and the benefits can be partially maintained for atleast a period of one year. The benefits of rehabilitation programme are further emphasized by a randomized case-control study by Toshima et al (1990) in which the researchers found better outcomes in those subjected to rehabilitation programme than who were treated with drugs alone. Education is important in the program because it enhances active participation in health care, increases coping skills, enhances the understanding of the disease, assists in self-management and increases adherence to treatment plan (Neish and Hopp, 1988). The type of exercises to be included is aerobic and resistance exercises (Bendsrup et al, 1997). Aerobic or endurance exercise training should be performed atleast 3-4 times a week for about 20-30 min per session. The intensity of exercise must be at least 50% of maximal oxygen consumption. The mainstay of endurance training is lower extremity training. Strength training or resistance exercises improve respiratory muscle strength (ATS, 2004). Many COPD patients suffer from anxiety and depression which decrease the coping ability of the patient. Psychological and behavioural interventions which include stress management, progressive muscle relaxation and panic control increase the coping skills of the patient (Renfroe, 1988). Nutritional advice is essential because both underweight and obesity can contribute to increased morbidity and mortality in COPD (Chailleux et al, 2005). Nutritional advice is based on the BMI. Nutritional intervention should be considered in all patients with BMI less than 21 kg per meter square, involuntary weight loss of >10% in the previous 6 months or >5% in the past one month, and also in cases where there is depletion in FFM (ATS, 2004). Nutrition advice consists of adaptation of patient's dietary habits supplemented by energy-dense supplements. The nutrition advised should avoid loss of appetite and at the same time prevent adverse metabolic and ventilatory efforts. Some research has questioned the benefits of nutritional supplements in COPD (Ferreira et al, 2000). According to Casaburi et al (2005), introduction of a bronchodilator like tiotropium can add to the benefits of the program. Physiotherapy Physiotherapy helps control of breathlessness by means of certain breathing techniques, relaxation and airway clearance. According to the NICE guidelines (2004), physiotherapy must be instituted to reduce work of breathing associated with COPD, to restore the maximum function of the patient and to improve respiratory and peripheral muscle weakness. Whether to administer physiotherapy at home or in the hospital/clinic is based on the severity of the disease and the ability to perform alone at home (Moore et al, 2009). Clinic-based physiotherapy is costly and often non-compliant. Hence many experts advise home-based exercise protocol for physical rehabilitation. Moore et al (2009) compared the benefits of home-based physiotherapy over clinic-based physiotherapy and reported that the benefits were similar in both when the proper protocol was followed. There are many techniques in physiotherapy which help to manage breathlessness. Positioning of body, control of breathing, chest clearance, exercise training and chest physiotherapy are some of the methods which are commonly employed to reduce breathlessness in COPD patients. Exercise trains the body to deliver more oxygen to the muscles so that day-to-day activities can be carried out without causing breathlessness and fatigue. Exercise must be started with small amounts and then gradually increased. Other benefits of exercise are relaxation, weight control and increased efficiency of heart. Exercise not only improves the stamina of respiratory muscles in COPD patients, but also improves the autonomic nervous control, thus decreasing heart rate variability during stress. Aerobic exercises also increase oxygen consumption and cause improvements in blood lactate, dyspnea at peak exercise, parasympathetic and sympathetic activities, and minute ventilation. This is evident from the study by Borghi-Silva et al (2009) in which a 6-week aerobic exercise training in moderate-severe COPD patients showed improvements in suboptimal performances. While imparting physical training, both upper extremity and lower extremity exercises must be included. Upper extremity training is important to help improvement of breathlessness and fatigue when activities which involve the accessory muscles of ventilation are involved. Some researchers do not see any added benefits with upper extremity exercises. Costi et al (2009) conducted a systematic review on the benefits of upper-extremity exercise in COPD patients and reported that there is not much evidence to support the definite need to include upper extremity exercise training in the rehabilitation regimen of COPD patients with breathlessness. Inspiratory muscle training which involves breathing at graded increase in resistance improves the strength of the inspiratory muscles, thus improving exercise performance and dysnea in day-to-day activities. This form of training is essential because in COPD, respiratory muscles need to work more and are actually compromised due to airway collapse and low elastic recoil. An improvement in the respiratory muscle performance is associated with decreased perception of breathlessness (Patessio et al, 1989). Whether interval physical training or continuous physical training is effective in COPD is often a brooded topic. Varga et al (2007) conducted a comparative study between 3 types of exercise training in patients with COPD, by allocating them into 3 groups. While the first group or 'C' group received supervised continuous training, 'I' group received intermittent training and 'S' group received self-paced training. Patients were allocated to the groups based on their travel convenience. 22 patients were allocated in the C-group, 17 in the I-group and 32 in the S-group. The training period was for 8 weeks. In the continuous group, exercise intensity of peak work rate of 80 percent was achieved through incremental exercise test. The patients were subjected to 45 minutes of cycling at this work rate, 3 times a week. Those in I-group were subjected to cycling for 30 minutes, during which time, the patients were asked to exercise at peak work rate of 90 percent for 2 minutes followed by work rate of 50 percent for one minute. 7.5 minutes prior to and also after this cycling exercise time, the patients were subjected to exercises of 50 percent work rate. The S-group performed unsupervised exercise in their home environment at their own pace for 45 minutes. Exercise intensity in both the supervised groups was held constant during the training program to enable effective comparison between the two types of training, continuous and intermittent. Pulmonary function tests, incremental exercise tests , pulmonary ventilation, gas exchange, carbon-di-oxide out put, lactic acidosis threshold, heart rate, oxygen saturation, 12-lead ECG and blood gas analysis were done before and after the study period in all the groups. The participant patients were also asked to answer an activity questionnaire. Statistical analysis using ANOVA was done and from the analysis it was evident that both the supervised groups, continuous and intermittent achieved similar exercise endurance. The third group, the self-pace training group had much inferior benefits. The study supported supervised high intensity rehabilitation, either intermittent or continuous, for improvement in breathlessness and work performance (Varga et al, 2007). In another similar study by Arnardottir et al (2006), the researchers conducted a randomized controlled trial to compare and ascertain the benefits of the effects of 3-minute interval training as against continuous training on various physiological and symptomatological aspects of patients with moderate to severe COPD, like physiological response, peak exercise capacity, dyspnea, functional capacity, health related quality of life and mental health. The study included 60 patients who were allocated to either interval training group (I) or continuous training group (c), after randomization. The participants exercised twice a week for 16 weeks. In the I-group, the target intensity was more than 80 percent and that in the study group was more than 65 percent. The tests used for evaluation were ergometer cycle test, spirometry, 12-minute walk test and cardiopulmonary test. Chronic Obstructive Disease Questionnaire (CODQ) was used to measure dyspnoea. Statistical analysis was done using ANOVA and student's t-test. The study demonstrated that training using 3 minute interval is efficient in the management of COPD. As far as work peak, VO2 and VCO2 were concerned, equal improvement was noted in both continuous and intermittent training. VE improved in continuous training only, but this the researchers attributed to decreased isotime frequency in the interval group. Other than these differences, dyspnoea, quality of life, mental health and functional capacity were similar in both the groups proving that both forms of exercise training are equally effective (Amadottir et al, 2006). Puhan et al (2005) conducted a systematic review of randomised controlled trials retrieved from various electronic databases and also through manual hand searches. The inclusion criteria for the study were randomised controlled trials which compared different modalities and intensities of exercise or a combination of these for patients suffering from COPD. Only standardised exercise protocol were included in the study because of scope for replication in practice clinically. The study also included only if patients with a definite diagnosis of COPD were included in their study. The main outcomes measures looked in the study were health-related quality of life, functional exercise capacity, maximum exercise capacity, exercise tolerance and physiological parameters like anerobic threshold and lactate. Data from all studies was reviewed and scrutinised by 2 separate reviewers independently. 15 articles were included in the study. The data was analysed using suitable statistical software and 95 percent confidence limits for differences between the studies was calculated. As far as continuous vs interval exercise was concerned, it was found that 3 studies compared these attributes, one of which, found increased oxygen consumption and lower lactate levels with continuous exercise as against interval exercise. However, interval exercise led to decrease in leg pain and increased maximum exercise capacity in that study. Another study showed that interval exercise improved 6 minute walking distance when compared to continuous exercise. The third trial showed similar improvement with respect to HRQL and peak oxygen consumption with respect to both the groups. The researchers opined that both types of exercise had similar outcomes. Beauchamp et al (2010) conducted a systematic review to compare interval exercise training against continuous exercise training and ascertain the effects of these two types of training on peak power, peak oxygen uptake, 6-minute walk test and quality of life related to health. The study included 8 randomised controlled trials from 6 databases. The total number of COPD patients included thus in the study were 388 patients. data from the studies was subjected to statistical analysis. From the results of the study it was evident that as far as peak power, peak oxygen uptake and 6- minute walk distance was concerned, no difference was noted between those who under went interval training and those who were subjected to continuous training. The authors concluded that since the effects of interval training are similar to continuous exercise training, interval training may be considered as an alternative to continuous training for patients suffering with varying degress of COPD. Coppoolse et al (1999) conducted a randomised controlled trial to evaluate various physiological responses to training at peak loads of 60 percent and also to compare the effects of interval training as against continuous training in the management of COPD. The study enrolled 21 patients with COPD, who were alloted to continuous training or interval training groups through randomisation. The participants were subjected to exercise training on cycle ergometer 5 days a week for minimum 30 minutes each day for total of 8 weeks. This study included only male patients for the purpose of homogeneity. Only stable patients were recruited into the inpatient pulmonary rehabilitation program after referral by respective pulmonary physician. Those exhibiting excellent response to bronchodilator therapy, patients with other health problems like neurological, coronary, endocrine and orthopedic problems and those with low arterial oxygen tensions were excluded in the study. The main outcomes measured in the study were physiological parameters like carbondioxide and oxygen tensions, lactate levels, lung function, Wmax and Vo2 max. Statistical analysis was used to analyse the data. Mann-Whitney U-test, Student's t-test and Wilcoxon log-rank test were used to analyse the data. From the results of the study, it was evident that continuous training led to increase in oxygen consumption, decrease in minute ventilation and decrease in carbon-di-oxide production during peak exercise activity. No change with regards to these parameters were seen in interval training. Also, decrease in lactic acid during submaximal exercise was seen more prominently in continuous training when compared to interval exercise training. However, peak work load increased only in the interval training group. maximal inspiratory mouth pressure increased in both the groups significantly. The results of the study are thus inconclusive and the authors opined that the physiological changes are a result of the various pathways used in the training and that more studies are warranted to ascertain as to which is a better form of exercise training for pulmonary rehabilitation in patients with COPD (Coppoolse et al, 1999). In yet another randomised controlled trial by Vogiatzis et al (2002), the researchers investigated and compared the impact of interval and continuous training on physiological response, exercise tolerance and quality of life. The study included 36 patients with COPD who were randomly assigned to either interval training group or continuous group. The continuous training group participants were subjected to exercise at 50 percent peak work rate by cycling ergometer for 40 minutes a day for 2 days a week for 12 weeks. Whereas, the interval training group participants were subjected to 100 percent peak work rate for 30 seconds, alternated by 30 seconds rest, for 40 minutes a day, for 2 days week for 12 weeks. The results of the study were analysed statistically and it was found that exercise tolerance and quality of life scores were similar in both the groups. the authors concluded that the benefits of both the types of training are similar in patients with COPD (Vogiatzis et al, 2002). Mador et al (2009) conducted a randomised control trial to compare continuous and interval training in COPD patients. 21 patients were recruited who were assigned to continuous and interval groups through random assigning. The main outcomes measured in the study were maximal work capacity, 6-minute walk distance, endurance exercise capacity and health-related quality of life. Both groups exercised 3 times a week for 8 week. Data from the two groups was analysed using statistical soft ware and results from the analysis proved that while exercise training significantly improved the outcomes in the patients, there was no difference in the improvement noted in both the groups. The authors opined that since interval training was better tolerated, it must be used as an alternative to those who did not tolerate continuous training. Thus, it is evident that exercise endurance training in COPD is very essential and it does not matter whether the training is delivered through interval exercise training or continuous exercise training. Results of the studies described above show that overall benefits to the patients with COPD in terms of exercise tolerance, health related quality of life, decrease in lactic acidosis, increase in percentage of work performance, increase in oxygen consumption and decrease in cardon-di-oxide retention are similar and hence any form of training can be instituted to the patients. Yoga is another intervention that improves gas exchange in moderate to severe COPD patients. This aspect has been studied by Pomidori et al (2009) who reported improvement in breathlessness in patients with COPD after short term yoga training. Physical training in the form of exercise within the context of pulmonary rehabilitation can improve exercise capacity, health-related quality of life and breathlessness in COPD patients. However, the intensity and duration of exercise that can be performed is limited by breathlessness and easy fatigability. The exercising capacity can be increased by several interventions like oxygen therapy and addition of titropium. Some experts recommend helium-hyperoxia during pulmonary rehabilitation to increase the intensity and duration of exercise training, thus improving the constant-load exercise time. (EVES et al, 2009). However, many researchers add little value to the benefits of these interventions. Exertional dysnea limits the usefulness of physiotherapy. Hence currently, researchers are looking into other modalities of managing breathlessness like transcutaneous neuromuscular electrical stimulation or NMES. Sillen et al (2007) conducted an extensive literature review pertaining to the usefulness of NMES in managing breathlessness in COPD. According to the literature review, NMES improves muscle strength, health status and exercise capacity significantly enough to be considered as a good means of rehabilitation in COPD patients. Conclusion COPD is a chronic incurable illness that causes intense suffering and affects quality of life. However, appropriate treatment and interventions can decrease the amount of suffering and help the patient lead a good health-related quality of life. The most progressive and frightening symptom of COPD is breathlessness which poses a challenge to the health professionals as far as management is concerned. The main forms of treatment for breathlessness are medical therapy and physical therapy. While medical therapy alone is useful in initial stages, introduction of physical therapy becomes essential as the disease progresses. Many experts prefer combination of pharmacological and physical interventions for effective management of breathlessness. Comprehensive pulmonary rehabilitation programme, along with bronchodilator therapy can decrease dyspnea, improve exercise tolerance, enhance quality of life and prevent complications and exacerbations. Exercise endurance training in COPD is very essential and it does not matter whether the training is delivered through interval exercise training or continuous exercise training. Results of the studies described above show that overall benefits to the patients with COPD in terms of exercise tolerance, health related quality of life, decrease in lactic acidosis, increase in percentage of work performance, increase in oxygen consumption and decrease in cardon-di-oxide retention are similar and hence any form of training can be instituted to the patients. References Arnardottir, R.H., Boman, G., Larsson, K., Hedenstrom, H., and Emtner, M. (2007). Interval training compared with continuous training in patients with COPD. Respiratory Medicine, 101, 1196–1204. American Thoracic Society/European Respiratory Society Task Force or ATS. (2004). Standards for the Diagnosis and Management of Patients with COPD. Retrieved on 22nd March, 2011 from http://www.thoracic.org/go/copd Borghi-Silva, A., Arena, R., Castello, V., Simoes, R.P., Martins, L.E., Catai, A.M., Costa, D. (2009). Aerobic exercise training improves autonomic nervous control in patients with COPD. Respiratory Medicine. Retrieved on 22nd March, 2011 from http://www.ncbi.nlm.nih.gov/pubmed/19464865?ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum Bendstrup, K.E., Ingemann, J. J., Holm, S., Bengtsson, B. (1997). Out-patient rehabilitation improves activities of daily living, quality of life and exercise tolerance in chronic obstructive pulmonary disease. Eur Respir J, 10, 2801–2806. Beauchamp, M.K., Nonoyama, M., Goldstein, R.S., et al. (2010). Interval versus continuous training in individuals with chronic obstructive pulmonary disease--a systematic review. Thorax, 65(2), 157-64. Brochard, L., Isabey, D., Piquet, J. et al. (1990). Reversal of acute exacerbations of chronic obstructive lung disease by inspiratory assistance with a face mask. N Engl J Med, 323, 1523–30. Brooks, D., Krip, B., Mangovski-Alzamora, S., Goldstein, R.S. (2002). The effect of postrehabilitation programmes among individuals with chronic obstructive pulmonary disease. Eur Respir J, 20, 20–29. Cambach, W., Chadwick-Straver, R.V., Wagenaar, R.C., van Keimpema, A.R., Kemper, H.C. (1997). The effects of a community-based pulmonary rehabilitation programme on exercise tolerance and quality of life: a randomized controlled trial. Eur Respir J.,10(1), 104-13. Coppoolse, R., Schols, A.M.W.J, Baarends, E.M., et al. (1999). Interval versus continuous training in patients with severe COPD: a randomized clinical trial. Eur Respir J., 14, 258±263. Casaburi, R., Kukafka, D., Cooper, C.B., et al. (2005). Improvement in exercise tolerance with the combination of tiotropium and pulmonary rehabilitation in patients with COPD. Chest, 127, 809–17. Chailleux, E., Laaban, J.P., Veale, D. (2003). Prognostic value of nutritional depletion in patients with COPD treated by long-term oxygen therapy: data from the ANTADIR observatory. Chest, 123, 1460–6. Costi, S., Di Bari, M., Pillastrini, P. (2009). Short-term efficacy of upper-extremity exercise training in patients with chronic airway obstruction: a systematic review. Phys Ther. , 89(5), 443-55. Dirksen, A., Dijkman, J.H., Madsen, F., et al. (1999). A randomized clinical trial of ?(1)-antitrypsin augmentation therapy. Am J Respir Crit Care Med, 160, 1468-1472. Eves, N.D., Sandmeyer, L.C., Wong, E.Y. (2009). Helium-hyperoxia: a novel intervention to improve the benefits of pulmonary rehabilitation for patients with COPD. Chest., 135(3), 609-18 Fromer, L., and Cooper, C.B. (2008). A Review of the GOLD Guidelines for the Diagnosis and Treatment of Patients With COPD. Medscape CME. Retrieved on 22nd March, 2011 from http://cme.medscape.com/viewarticle/582762 Ferreira, I.M., Brooks, D., Lacasse, Y., Goldstein, R.S. (2000). Nutritional support for individuals with COPD: a meta-analysis. Chest, 117, 672–678. Global Initiative for Chronic Obstructive Lung Disease (GOLD). (2006). Global Strategy for the Diagnosis, Management, and Prevention of Chronic Obstructive Pulmonary Disease. Retrieved on 22nd March, 2011 from http://www.goldcopd.com/Guidelineitem.asp?l1=2&l2=1&intId=989 Kramer, N., Meyer, T.J., Meharg, J. et al. (1999). Randomized, prospective trial of noninvasive positive pressure ventilation in acute respiratory failure. Am J Respir Crit Care Med., 151, 1799–806. Moore, J., Fiddler, H., Seymour, J., Grant, A., Jolley, C., Johnson, L., Moxham, J. (2009). Effect of a home exercise video programme in patients with chronic obstructive pulmonary disease. J Rehabil Med., 41(3), 195-200. Neish, C.M., and Hopp, J.W. (1988). The role of education in pulmonary rehabilitation. J Cardiopulm Rehabil, 11, 439–441. NICE Guidelines. (2004). Chronic Obstructive Pulmonary Disease. Retrieved on 22nd March, 2011 from http://www.nice.org.uk/nicemedia/pdf/CG012_niceguideline.pdf Nichol, K.L., Baken, L., Nelson, A. (1999). Relation between influenza vaccination and outpatient visits, hospitalization, and mortality in elderly persons with chronic lung disease. Ann Intern Med., 130, 397–403. Official statement of the American Thoracic Society. (1999). Pulmonary rehabilitation. Am J Respir Crit Care Med., 159, 1666–1682 Patessio, A., Rampulla, C., Fracchia, C., et al. Relationship between the perception of breathlessness and inspiratory resistive loading: report on a clinical trial. Eur Respir J., 2, 587–91. Pomidori, L., Campigotto, F., Amatya, T.M., Bernardi, L., Cogo, A. (2009). Efficacy and tolerability of yoga breathing in patients with chronic obstructive pulmonary disease: a pilot study. J Cardiopulm Rehabil Prev., 29(2), 133-7. Puhan, M.A., Schunemann, H.J., Frey, M., et al. (2005). How should COPD patients exercise during respiratory rehabilitation? Comparison of exercise modalities and intensities to treat skeletal muscle dysfunction. Thorax, 60, 367–375. Renfroe, K.L. (1988). Effect of progressive relaxation on dyspnea and state anxiety in patients with chronic obstructive pulmonary disease. Heart Lung, 17, 408–413. Ries, A.L., Kaplan, R.M., Limberg, T.M., Prewitt, L.M. (1995). Effects of pulmonary rehabilitation on physiologic and psychosocial outcomes in patients with chronic obstructive pulmonary disease. Ann Intern Med., 122(11), 823-32 Sharma, S. (2006). Chronic Obstructive Pulmonary Disease. Emedicine from WebMD. Retrieved on 22nd March, 2011 from http://emedicine.medscape.com/article/297664-overview Silverman, E.K., and Speizer, F.E. (1996). Risk factors for the development of chronic obstructive pulmonary disease. Med Clin North Am., 80, 501–522. Snider, G.L. (1996). Reduction pneumoplasty for giant bullous emphysema. Implications for surgical treatment of nonbullous emphysema. Chest, 109, 540–548. Sillen, M.J., Speksnijder, C.M., Eterman, R.M.., et al. (2009). Effects of Neuromuscular Electrical Stimulation of Muscles of Ambulation in Patients With Chronic Heart Failure or COPD: A Systematic Review of the English-Language Literature.Chest, 42(1), 22-44. Shahin, B., Germain, M., Kazem, A., and Annat, G. (2008). Benefits of short inspiratory muscle training on exercise capacity, dyspnea, and inspiratory fraction in COPD patients. Int J Chron Obstruct Pulmon Dis., 3(3), 423–427. Sullivan, S.D., Ramsey, S.D., Lee, T.A. (2000). The economic burden of COPD. Chest, 117, 5S–9S. Thurlbeck, W.M.(1990). Pathophysiology of chronic obstructive pulmonary disease. Clin Chest Med., 11(3), 389-403. Toshima, M.T., Kaplan, R.M., Ries, A.L. (1990). Experimental evaluation of rehabilitation in chronic obstructive pulmonary disease: short-term effects on exercise endurance and health status. Health Psychol., 9(3), 237-52. Varga, J., Porszasz, J., Boda, K., Casaburi, R., and Somfay, A. (2007). Supervised high intensity continuous and interval training vs. self-paced training in COPD. Respiratory Medicine, 101, 2297–2304. Vogiatzis, I., Nanas, S., and Roussos, C. (2002). Interval training as an alternative modality to continuous exercise in patients with COPD. Eur Respir J., 20, 12–19. Weitzenblum, E., Sautegeau, A., Ehrhart, M., Mammosser, M., Pelletier, A. (1985). Long-term oxygen therapy can reverse the progression of pulmonary hypertension in patients with chronic obstructive pulmonary disease. Am Rev Respir Dis., 131, 493–498. Williams, T.J., Grossman, R.F., Maurer, J.R. (1990). Long-term functional follow-up of lung transplant recipients. Clin Chest Med., 11, 347–358. Zielinski J. (1999). Effects of long-term oxygen therapy in patients with chronic obstructive pulmonary disease. Curr Opin Pulm Med., 5, 81–87. Read More