The American Thoracic Society (ATS) has updated its official statement on pulmonary rehabilitation in patients with chronic respiratory impairment. The report, an update of the 1981 ATS statement, outlines the scope of pulmonary rehabilitation and provides data on its benefits, patient assessment and the essential components of a pulmonary rehabilitation program. It concludes with an overview of the areas in which future research is needed. The report appears in the May 1999 issue of American Journal of Respiratory and Critical Care Medicine. The document is available on the World Wide Web to subscribers of ATS Journals Online (http://www.atsjournals.org).
According to the ATS report, the goals of pulmonary rehabilitation are to reduce symptoms, decrease the degree of disability, increase the patient's participation in physical and social activities and improve the patient's quality of life. In addition to exercise training, pulmonary rehabilitation encompasses patient education, psychosocial and behavioral intervention and outcome assessment. The following is a summary of the ATS statement.
Benefits of Pulmonary Rehabilitation
According to the report, studies have shown that pulmonary rehabilitation increases the level of exercise a patient can perform and decreases the degree of dyspnea for a given level of exercise. For example, one study that compared the effects of standard medical therapy and a home-based program demonstrated a 21 percent increase in the maximal work rate after 18 months of participation in the home-based program.
The effects of pulmonary rehabilitation on exercise endurance can be sizable. A controlled study of eight weeks of outpatient pulmonary rehabilitation revealed that the endurance time on the treadmill increased 10.5 minutes in the rehabilitation group. This change represented an 85 percent increase over baseline. Improvements in dyspnea and quality of life are other benefits of pulmonary rehabilitation.
According to the report, controlled trials have also shown that pulmonary rehabilitation is associated with a trend toward a decrease in the use of health care resources, including a reduction in the number and duration of hospitalizations.
Patient Selection and Assessment
The report states that pulmonary rehabilitation is indicated for patients with chronic respiratory impairment who are dyspneic, have reduced exercise tolerance or experience a restriction in activities. The patient's symptoms, disability and handicap, not the severity of lung impairment, dictate the need for pulmonary rehabilitation. Thus, the statement emphasizes that there are no pulmonary function criteria for determining the need for pulmonary rehabilitation. Exclusion criteria for rehabilitation may include the presence of comorbid conditions, such as severe arthritis and unstable angina, that prohibit exercise training.
Assessment of the patient's suitability for pulmonary rehabilitation should include a determination of the severity of the respiratory impairment and morbidity. An assessment to ascertain the patient's knowledge base and learning needs is also helpful. Baseline exercise testing is important for assessing the patient's exercise capacity and for formulating exercise training that meets the patient's needs. Measurement of respiratory muscle strength and peripheral muscle strength may be useful, as may an assessment of the patient's ability to perform activities of daily living, cognitive function, emotional state and nutritional status.
Essential Components of Pulmonary Rehabilitation
According to the report, the four major components of pulmonary rehabilitation include exercise training, education, psychosocial and behavioral intervention and outcome assessment.
Exercise training. The report indicates that studies have shown a high level of exercise training (i.e., 60 percent of the maximal work rate, above the anaerobic threshold) produces greater improvement in maximal and submaximal exercise responses in patients with chronic obstructive pulmonary disease than does a low level of exercise training. According to the ATS statement, pulmonary rehabilitation programs usually emphasize endurance training, with periods of exercise lasting for about 20 to 30 minutes two to five times a week. The heart rate is cited as a reasonable parameter for measuring training intensity.
In patients who cannot train at 60 percent of their maximal work load for a prolonged period, interval training in the form of two to three minutes of high-intensity (60 to 80 percent of maximal exercise capacity) exercise is recommended. The periods of intense exercise can be alternated with periods of rest. Studies have shown that interval training in healthy subjects produces effects similar to those of endurance training.
Endurance training of the upper extremities is recommended in addition to endurance training of the lower extremities. Most pulmonary rehabilitation programs use, alone or in combination, a stationary cycle or walking for building endurance in the legs.
Strength training is also recommended, although the report notes that few studies have evaluated the effectiveness of this activity in patients with pulmonary disease. Two randomized controlled studies suggest that it may be important. Respiratory muscle training is another component of the exercise program.
The optimal frequency and intensity of exercises needed to maintain the fitness achieved with rehabilitation have not yet been determined. In addition, the role of brief periods of supervised training after an exacerbation of respiratory disease has not been delineated by clinical studies.
Patient education. According to the ATS statement, patient education is an integral component of a pulmonary rehabilitation program. Important subject areas include breathing retraining (such as pursed-lip breathing and diaphragmatic breathing), techniques for energy conservation and the proper use of medications. Education and discussions about end-of-life issues, such as intubation and mechanical ventilation, are also often incorporated into a pulmonary rehabilitation program.
Psychosocial and behavioral intervention. Problems such as anxiety, depression and difficulties coping with chronic pulmonary disease can be addressed during pulmonary rehabilitation. Educational sessions and support groups are useful for helping the patient learn coping skills for managing stress.
Outcome assessment. According to the ATS statement, measurement of the patient's change in performance can help reinforce the gains made during pulmonary rehabilitation. The degree of improvement may be assessed by the use of incremental exercise testing on a stationary bicycle or treadmill. Such factors as dyspnea and leg fatigue during exertion can be rated. Changes in endurance capacity may also be measured. Walking tests are a useful tool for evaluating the results of training. For example, patients can be instructed to walk as far as possible in a corridor or large room at their own pace during a specified period of time. Another walking test involves having patients repeatedly walk the same distance at gradually increasing speeds.
Future Directions for Pulmonary Rehabilitation
The ATS statement concludes with a section on areas that need further study or research. These include research on the essential components of a pulmonary rehabilitation program; information on the intensity, duration and optimal form of exercise training for patients with pulmonary disease; methods for improving long-term adherence to exercise training; and the role of preoperative pulmonary rehabilitation in patients preparing for a major surgical procedure.