Chronic obstructive pulmonary disease (COPD) is a progressive and irreversible decline in lung function attributed to cigarette smoke exposure,1 numerous other respiratory irritants, oxidant overload,2 and chronic inflammation.3,4 COPD includes emphysema (a permanent destructive enlargement of the airspaces within the lung and destruction of the vascularity); chronic bronchitis (inflammation of the bronchi and secretions); asthma (although many pulmonary authorities separate asthma from COPD—ed); and bronchiectasis (abnormal stretching and enlarging of the respiratory passages caused by mucus blockage). Bronchiectasis is an under/misdiagnosed obstructive lung disease.5 The National Center for Health Statistics notes that morbidity and mortality for COPD are escalating, as are associated health care expenditures.6 COPD often presents as a comorbid condition complicating medical care delivery, outcomes, and medical costs. When emphysema and bronchitis are considered only, mortality ranks fourth overall and is projected to increase to third by 2020; also, it is the only major disease with an escalating death rate. The National Heart, Lung, and Blood Institute (NHLBI) estimates that 12.1 million adults 25 years and older were diagnosed in 2001; moreover, 16 million may now be diagnosed—with an additional 14 million awaiting diagnosis. In 2002, the associated direct medical care costs exceeded $32 billion with another $14+ billion estimated for indirect costs. Thus, COPD is a significant chronic disease process that is exerting its toll on human life and suffering with increasing incidence and prevalence rates, yet only modest NIH research dollars are allocated.7
Medical treatment for COPD is aimed at eliminating exposure to the causative agent(s), reducing the imposed airflow limitation and air trapping in the lung, improving gas exchange, minimizing or eliminating inflammation, and addressing associated comorbidities. Ongoing maintenance therapies are required to ensure that lung function is optimized, given the degree of lung and airway disease present. Following stabilization of the disease process and ensuring optimization of medical therapies, patients should be considered for pulmonary rehabilitation—a medical delivery strategy that enhances patient knowledge and improves understanding of the disease process, optimization of medications and oxygen, nutritional status, and rapid action plans is necessary for enhancing quality of life and outcomes. Pulmonary rehabilitation and disease management have achieved variable levels of success,8-12 yet many clinicians do not fully appreciate the potential outcomes possible for patients with mild to advanced lung disease who participate in a pulmonary rehabilitation program. Using a multidimensional delivery process, the goals and objectives for improving function and enhancing medical delivery for patients with COPD can be achieved. While many delivery models have been used, no single model has emerged as the gold standard; however, one universal finding is that exercise training does improve function and this improved function is associated with an enhanced quality of life.13-15 This paper reviews our present understanding of exercise interventions for patients with COPD and associated outcomes while suggesting a transition to a more comprehensive disease management process.
A large, convincing body of knowledge has demonstrated significant benefits of pulmonary rehabilitation in patients with COPD. The data is very limited for patients with other lung diseases. Prior to entering a pulmonary rehabilitation program, a detailed medical, physiologic, and quality-of-life assessment is necessary to tailor the program for optimal impact and safety. The assessment process will help identify areas of greatest need and will document baseline values. Following careful review, a treatment plan will be devised with specific goals outlined. Goals should be established with patient input and preferences and, where possible, tailored to afford maximal patient and family involvement and understanding.
Comorbid conditions should be identified and considered in the treatment plan. For example, patients with orthopedic problems limiting exercise, significant cardiovascular disease, or cognitive impairment may be limited in their ability to exercise or comprehend the care plan. The need for supplemental oxygen while exercising should be established. Even in the absence of arterial oxygen desaturation, supplemental oxygen may improve exercise capacity and accelerate the training process by reducing the drive to breathe and lessening dyspnea at any given work rate; this enables the patient to exercise at a higher intensity and facilitates the training process.16-19
Patients who are active smokers have been excluded from pulmonary rehabilitation programs. Smoking is considered to be a primary disorder that should always be addressed. There is no evidence that present smokers will not benefit from rehabilitation, however. In fact, smokers without lung disease can benefit from exercise training albeit perhaps to a lesser degree than the nonsmoker. Further, evidence suggests that participation in exercise may aid in the smoking cessation process.
The success of rehabilitation programs can be attributed to the team of professionals, the patient and family, establishment of realistic goals and timelines, and the ongoing practice of rehabilitation/exercise techniques away from the formal setting. From the onset of rehabilitation, patients and care providers should focus on the long-term process and selecting exercise practices that can be incorporated into patients’ lifestyles for the rest of their lives. After establishing a high-quality medical treatment plan and oxygen prescription for the stabilized patient, training should commence using a variety of exercises targeted to the needs of the individual patient. The patient should be instructed to use their short-acting bronchodilator medication(s) about 20 minutes prior to exercise to ensure optimal bronchodilation during exercise training. Nutritional status also should be evaluated and optimized.20-23
Aerobic exercise involving large muscle groups is used to enhance cardiopulmonary performance. Consideration should be given to intensity, duration, frequency, and mode of exercise. New and exciting data regarding intensity of exercise have emerged in the past decade. Because COPD patients are limited by airflow obstruction, pushing patients to the peak of their airflow limitation should be advocated, provided that no comorbid contraindications exist. This intensity of exercise will create an unpleasant sensation of dyspnea, yet will improve the likelihood for a training response. This intensity level should be phased in over a 2- to 3-week period or as tolerated by the patient. We suggest that patients initiate training for 15 to 20 minutes per session and progressively increase their training to 40 to 50 minutes per session, two to three times per week in the formal setting. At the onset of training, patients may need to complete many small exercise periods (eg, 4 minutes exercise; 1 minute rest) to reach the 15- to 20-minute continuous training level commonly recommended. Exercise training should be supplemented with daily home exercise of varying intensity and duration, depending on formal program participation that day.
To counter dyspnea for hypoxemic, as well as nonhypoxemic, patients, supplemental oxygen is advocated. COPD patients are limited by airflow obstruction, dyspnea, and increasing end-expiratory lung volume (EELV) or dynamic hyperinflation as ventilatory demand increases.24,25 Dynamic hyperinflation places the respiratory muscles at a mechanical disadvantage, forcing the operating range of tidal breathing near total lung capacity, which is at the upper portion of the thoracic compliance curve. This increases the energy cost of breathing. Supplemental oxygen meets the metabolic demands for oxygen and alters the breathing pattern by reducing tidal volume and respiratory rate at submaximal exercise levels. Thus, exercise tolerance can be increased at constant load exercise, and patients will be able to train at higher work rates with supplemental oxygen administration, even in the absence of hypoxemia.26-28 Since training reduces exertional dyspnea, perceived dyspnea ratings may be used to assist in selecting the training work rates and determining exercise intensity throughout the training period. Commonly used dyspnea assessment instruments include Borg scores and Visual Analogue Scales.29
Resistance training is advocated and should become part of the normal training protocol for all patients.30 As we age, we lose muscle mass and strength. For COPD patients, this process is accelerated, especially when they are on long-term systemic corticosteroids combined with a sedentary lifestyle. Resistive training should be initiated at about 30% to 40% of a peak single movement effort, and the number of repetitions performed during a single bout should be increased to 10 to 12 repetitions gradually over a 2- to 3-week period or as tolerated. Thereafter, the resistance can be increased as tolerated based on the therapeutic goal. Patients are instructed to maintain a normal breathing pattern and to use supplemental oxygen as required. While many strategies for resistive training have emerged, no single strategy is superior. To build maximal strength, heavier resistances and fewer repetitions (three to four repetitions) should be used. For strength and conditioning, lighter resistances (% of maximal effort) and eight to 12 repetitions per session should be used while alternating between large muscle groups; this will heighten the training response and avert fatiguing any specific muscle group.31
For COPD patients, inspiratory muscle strength and endurance may be reduced. Maximal inspiratory and expiratory pressures can be measured at the mouth and reflect the strength of the respiratory muscles.32 Respiratory muscle endurance can be assessed using the maximal voluntary ventilatory capacity or other respiratory endurance measures.33 Respiratory muscle training can improve strength, yet this training is task specific and the benefits tend not to generalize to other muscle groups.34,35 A number of respiratory muscle-training studies have been performed that provide encouraging results; however, information on intensity, duration, and frequency of training is not well documented, although overall improvements in exercise capacity, respiratory muscle function, and dyspnea support the use of specific respiratory muscle training.36 Furthermore, for patients with COPD, a respiratory muscle trained state may already exist due to shifting tidal volumes operating within the patient’s flow-volume loop (dynamic hyperinflation). For these individuals, periodically resting the respiratory muscles may be helpful in increasing the patient’s ability to perform exercise, lessen dyspnea, and improve quality of life.37,38
Numerous positive benefits from participation in a pulmonary exercise program have been documented using a diverse set of experimental designs, a wide array of patients with varying degrees of airway obstruction, and many training intervention approaches. It is becoming evident that patients who train at higher intensities reap the greatest benefits and that these intensities are far less than those possible for normal age-matched controls due to airflow limitation and dyspnea.39 Clearly, submaximal exercise capacity is enhanced, and this enhanced capacity is typically associated with an improved quality of life.12, 40-42 Recent studies44,45 suggest that a clinically important gain in distance walked should exceed 50 meters.
COPD predisposes the patient to changes in body composition, including decreased muscle cross-sectional area, a loss of free-fat mass, and decreased fat mass. These negative changes can be reversed/improved through exercise training. Strength training and good nutrition can promote increases in muscle strength, increased free fat mass, and improved muscle function.45,46 The addition of testosterone and anabolic steroids, in carefully selected patients, may enhance this response.47 Also, aerobic exercise training increases muscle oxidative capacities while improving overall muscle performance.45,46 Exercise training will reduce lactic acid production, improve blood gases, alter muscle energetics, and, thus, extend exercise capacity.48,49 There is some indication in normal individuals that exercise training may reduce inflammation, but we lack quality studies in patients with COPD to confirm this speculated potential.50 Redox states may be enhanced as exemplified by higher levels of antioxidants such as glutathione or other radical scavengers.1,51 The overall significance of changes in redox state is unknown, yet less inflammation and improved cell function are suggested.
The positive benefits noted above represent the most consistent findings in the literature. Additionally, quality of life as assessed by generic as well as disease-specific instruments demonstrates positive outcomes in the presence of improved physical function and dyspnea reduction is commonly experienced.10,43,52-55
Pulmonary rehabilitation with exercise training represents a partial exploration toward a comprehensive disease management process for patients with COPD. Disease management has been implemented for other chronic diseases, including congestive heart failure, diabetes, arthritis, hypertension, obesity, and asthma, with good success. It is time to move the management of COPD patients to a higher level as well. Not only would this include a rehabilitation and maintenance program, it will incorporate an ongoing dialogue between the physician and patient to monitor and react to patient needs in a timely and effective manner. The management process will include all stakeholders (patient, family, physician, respiratory therapist, nurse, dietician, pharmacist, exercise specialist, home health personnel, payors, and others) to collectively integrate disease management as an ongoing and immediate care delivery process. Prevention of exacerbations and immediate response action plans may be effectively utilized to minimize respiratory insults and prevent hospitalizations. Function in all dimensions will be maximized, thereby enhancing exercise performance and quality of life and minimizing dyspnea. Using a disease management process, the benefits of pulmonary rehabilitation may be extended and optimized,56 patient success extended, quality of life enhanced, and medical care costs contained, while patient understanding and knowledge are improved.
Rick Carter, PhD, MBA, is professor of exercise physiology and physiology; Anna Tacon, PhD, is associate professor of health sciences; Jim Williams, PhD, is associate professor of exercise physiology and physiology, Texas Tech University and Texas Tech University Health Sciences Center, Lubbock. Brian Tiep, MD, is medical director of the Respiratory Disease Management Institute, and associate professor of family medicine, Western University of Health Sciences, Pomona, Calif.
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