American Journal of Respiratory and Critical Care Medicine

Introduction

The Scope of Pulmonary Rehabilitation

 Benefits of Pulmonary Rehabilitation

  Impairment

  Disability

  Handicap

  Survival

  Economics

 Patient Selection and Assessment

 Benefits Across Settings: Inpatient, Outpatient, and Home-    based Pulmonary Rehabilitation

The Essential Components of Pulmonary Rehabilitation

 Exercise Training

 Education

 Psychosocial and Behavioral Intervention

 Outcome Assessment

Future Directions for Pulmonary Rehabilitation

Since the last Statement by the American Thoracic Society on Pulmonary Rehabilitation in 1981 (1), the efficacy and scientific foundation of pulmonary rehabilitation have been firmly established. The belief that there is little hope for improvement in patients with advanced chronic respiratory disease has been refuted, and pulmonary rehabilitation is no longer viewed as a last-ditch effort to manage patients with severe respiratory impairment. Strategies employed by pulmonary rehabilitation programs are now an integral part of the clinical management and health maintenance of patients with chronic respiratory disease who remain symptomatic or continue to have decreased function despite standard medical management.

The principal goals of pulmonary rehabilitation are to reduce symptoms, decrease disability, increase participation in physical and social activities, and improve the overall quality of life for individuals with chronic respiratory disease (2). These goals are achieved through several processes, including exercise training, patient and family education, psychosocial and behavioral intervention, and outcome assessment. The rehabilitation intervention is geared toward the unique problems and needs of each patient and is implemented by a multidisciplinary team of health care professionals. On the basis of these concepts, the American Thoracic Society has adopted the following definition: Pulmonary rehabilitation is a multidisciplinary program of care for patients with chronic respiratory impairment that is individually tailored and designed to optimize physical and social performance and autonomy.

The purposes of this Statement are to define the scope of pulmonary rehabilitation, outline the essential components in the rehabilitation process, and make recommendations for future investigation.

Pulmonary rehabilitation reduces symptoms, increases functional ability, and improves quality of life in individuals with chronic respiratory disease, even in the face of irreversible abnormalities of lung architecture. These benefits are possible since often much of the disability and handicap result not from the respiratory disorder per se, but from secondary morbidities that are often treatable if recognized (Table 1). For example, although the degree of airway obstruction or hyperinflation of chronic obstructive pulmonary disease does not change appreciably with pulmonary rehabilitation, reversal of muscle deconditioning and better pacing enable patients to walk farther with less breathlessness. Although pulmonary rehabilitation should be beneficial in the pediatric population, controlled studies have not been performed in this group.

Table 1. CONSEQUENCES OF RESPIRATORY DISEASE

Types of Secondary MorbidityMechanism(s)
Peripheral muscle dysfunctionDeconditioning, steroid myopathy, ICU neuropathy, malnutrition, decreased lean  body mass, fatigue, effects of hypoxemia, acid-base disturbance, electrolyte  abnormalities
Respiratory muscle dysfunctionMechanical disadvantage secondary to hyperinflation, malnutrition, diaphragmatic  fatigue, steroid myopathy, electrolyte abnormalities
Nutritional abnormalityObesity, cachexia, decreased lean body mass
Cardiac impairmentDeconditioning, cor pulmonale
Skeletal diseaseOsteoporosis, kyphoscoliosis
Sensory deficits (impaired vision,  hearing, etc.)Medications (e.g., steroids, diuretics, antibiotics)
PsychosocialAnxiety, depression, guilt, panic, dependency, cognitive deficit, sleep disturbance,  sexual dysfunction

Benefits of Pulmonary Rehabilitation

Since the previous American Thoracic Statement in 1981, the clinical effectiveness of comprehensive pulmonary rehabilitation has been established. A summary of the scientific basis for the individual components of pulmonary rehabilitation have been recently outlined in a combined American College of Chest Physicians and American Association of Cardiovascular and Pulmonary Rehabilitation panel report (3). In view of this, and since pulmonary rehabilitation involves a comprehensive approach to care, only those trials involving the entire rehabilitation process are highlighted in this document (Table 2) (4-11).

Table 2. RANDOMIZED CONTROLLED TRIALS OF PULMONARY REHABILITATION

InvestigatorStudy DesignPatients (n)Patient CharacteristicsOutcomes
Goldstein,  1994 (4)8 wk. Inpatient rehabilitation  followed by 16 wk partially  supervised home training  versus control group given  conventional care 89Treatment group mean age, 66 yr;  FEV1, 35% predTreatment group had significant increase (37.9 m) in 6MWD and  submaximal cycle endurance time (4.7 min), and significant  improvements in dyspnea, emotion, and mastery components  of the CRQ or CRDQ, and dyspnea as measured by the TDI  (+2.7 units).
Reardon,  1994 (5)6 wk. Comprehensive outpatient  rehabilitation versus  untreated control group 20Treatment group mean age, 66 yr;  FEV1, 35% predNo significant change in maximal exercise testing in either group.  Rehabilitation patients had significantly lower exertional  dyspnea during exercise testing and lower overall dypsnea  measured by the TDI.
Ries,  1995 (6)8 wk. Comprehensive outpatient  rehabilitation versus  educational control group119Treatment group mean age, 61.5  yr; FEV1, 1.21 LSignificant postrehabilitation improvement in V˙ o 2max and treadmill  endurance time, and decreased exertional and overall dyspnea.  No significant postrehabilitation change in HRQL (Quality of Well-  Being score), number of hospital days, or survival.
Wijkstra,  1996 (7, 8)12 wk. Home-based multi-  disciplinary rehabilitation  versus untreated control  group 43Treatment group mean age, 64 yr;  mean FEV1, 44% predTreatment group showed a significant increase in work rate, V˙o 2max,  and 6MWD (438 to 447 m), and decreases in exertional dyspnea  and inspiratory muscle workrate during incremental cycle exercise  testing. HRQL (CRDQ) increased significantly in treatment group.
Strijbos,  1996 (9)12 wk. Hospital-based outpatient  versus 12 wk home rehabilita-  tion versus untreated control  group. Follow-up, 18 mo 45Treatment group mean ages, 61.2  and 60.0 yr; FEV1, 40.4 and  45.5% pred in outpatient and  home rehab groupsBoth outpatient and home-based rehabilitation had increases in  maximal cycle work level, 4MWD, and decreases in exertional  dyspnea compared with the control group. Gains made in the  outpatient group tended to peak after formal rehabilitation then  gradually decline. Those in home-based rehabilitation tended to  gradually increase during the 18-mo obervation period.
Bendstrup,  1997 (10)12 wk. Hospital-based outpatient  rehabilitation versus untreated  control group 32Treatment group mean age, 64 yr;  mean FEV1, 1.02 LAt 12 and 24 wk, the treatment group had a significant increase in  6MWD (113 m versus 21 m) and activities of daily living than the  control group. CRDQ scores were significantly higher at 24 wk.
Wedzicha,  1998 (11)8 wk. Exercise and education  versus education alone.  Hospital-based or home-  based depending on level  of dyspnea126Mean ages ranged from 69 to 73  yr; FEV1 from 36 to 38% predIn the group with moderate dyspnea (n = 66), exercise training and  education led to improvement in the shuttle walking distance and  health status compared with education alone. Exercise ability and  health status did not significantly change in either group with  severe dyspnea.

Definition of abbreviations: 6MWD = 6 minute walk distance; CRQ or CRDQ = Chronic Respiratory Disease Questionnaire; TDI = Transitional Dyspnea Index; V˙ o 2max = maximal minute ventilation.

Patient-specific outcomes are described according to the International Classification of Impairments, Disabilities, and Handicaps developed by the World Health Organization (12). Under this classification, respiratory impairment is a loss or abnormality of psychologic, physiologic, or anatomic structure or function resulting from respiratory disease. Impairment is the exteriorization of a pathologic state, and is usually determined by a laboratory measurement. For respiratory disease, impairment is reflected in a decreased FEV1 and airtrapping on pulmonary function testing or decreased quadriceps force on peripheral muscle function testing. Respiratory disability refers to the inability to perform an activity in the manner within the normally expected range because of lung disease. This would include reductions in dynamic function, task limitation, and physical performance. For pulmonary rehabilitation, this is often determined by field tests such as the timed walk test or questionnaire such as the Baseline and Transitional Dyspnea Indexes (13). Respiratory handicap represents the disadvantage resulting from an impairment or disability within the context of the patient's ability to perform in society or fill expected roles. For example, a reduced exercise performance during a timed walk test is disability, but the resultant inability to maintain employment is handicap. A reduction in functional performance (which focuses on activities of daily living) may be considered midway between disability and handicap.

The World Health Organization classification of impairment, disability, and handicap is suitable for categorizing much of the morbidity arising from respiratory disease. However, dyspnea, the overriding symptom of most patients referred for pulmonary rehabilitation, does not fit neatly into this schema. Because exertional dyspnea is usually rated during exercise testing and overall dyspnea is commonly assessed through its impact on daily activities, it is included under disability. Other outcomes such as survival and cost-benefit analysis will be discussed separately.

Impairment. Airflow obstruction, an impairment that is integral to the diagnosis of chronic obstructive pulmonary disease, is generally considered to be irreversible with either standard medical therapy or with pulmonary rehabilitation. Therefore, most studies evaluating the effectiveness of pulmonary rehabilitation use the FEV1 and other measures of pulmonary impairment as descriptors of the patient population rather than as outcome measures. Other impairments common to chronic respiratory disease such as weakness and dysfunction of peripheral and respiratory muscles, anxiety and depression, and abnormalities of nutrition and body composition are more responsive to treatment. These will be discussed in later sections.

Disability. Studies using exercise as an outcome measure have shown either an increase in the exercise performed or a decrease in dyspnea for a given level of exercise or both. A meta-analysis of 11 studies found a positive effect size for exercise with training (Figure 1) (14). This positive effect size for exercise is noteworthy since the course of COPD is progressively downhill.

Significant increases in maximal exercise capacity measured during incremental exercise testing have been observed after pulmonary rehabilitation. For example, a 1.5 metabolic equivalent increase (33% increase over baseline) in maximal treadmill work rate and a 0.11 L/min increase (9% increase over baseline) in maximal oxygen consumption was demonstrated in a clinical trial at the completion of 8 wk of outpatient pulmonary rehabilitation (6). Similarly, an eight watt increase in maximal workrate on cycle ergometry (11% increase over baseline) resulted after 12 wk of home-based pulmonary rehabilitation (8). In a study comparing outpatient, hospital-based rehabilitation and home-based rehabilitation with a control group receiving standard medical therapy, the outpatient program showed an initial 20% increase in maximal work rate after rehabilitation, but this improvement gradually decreased in the 18-mo follow-up period (9). The home-based rehabilitation program, on the other hand, showed a gradual increase in maximal work rate, peaking at 21% above baseline at 18 mo.

Steady-state exercise endurance also improves substantially after pulmonary rehabilitation. In an 8-wk study of inpatient pulmonary rehabilitation followed by 16 wk of outpatient supervision, stationary cycle ergometer endurance time at 60% of the symptom-limited maximal power output increased 4.7 min over that in a control group (4). This represented a 38% increase over the baseline measurement of the treatment group. Even more impressively, the controlled study evaluating outpatient rehabilitation described earlier (6) demonstrated a 10.5-min increase in treadmill endurance time in the treatment group, an 85% increase over baseline.

The 6-min walk distance as a measure of exercise performance has shown increases of 38 m in pulmonary rehabilitation patients (inpatient) compared with control subjects (4). This distance exceeds the minimum 30 m for a clinically important change for the 6-min walk test estimated by one method (15), but is below the 54-m estimate of clinical significance determined by another (16). In a more recent, controlled 12-wk study of outpatient pulmonary rehabilitation (10), the 6-min walk distance increased by 80 m at 6 wk (halfway into the program), 113 m at the end of the program, and 96 m 12 wk after the program ended. These changes were all significantly greater than those of a control group. Using a 4-min walk test, an approximately 40-m increase has been shown with outpatient hospital-based and a 30-m increase with home-care pulmonary rehabilitation (9).

Dyspnea has also been frequently included as an outcome measure for pulmonary rehabilitation. The recent Statement on Dyspnea by the American Thoracic Society summarizes the effects of exercise training on decreasing dyspnea (Figure 2) (17). The beneficial effects from exercise training affects not only dyspnea, but this effect on dyspnea appears to exceed that from bronchodilator or oxygen therapy.

Improvements in overall and exertional dyspnea have been demonstrated in controlled trials of comprehensive pulmonary rehabilitation. A clinically meaningful decrease in dyspnea was found after inpatient pulmonary rehabilitation using the Transitional Dyspnea Index (TDI). A 2.3-unit increase in the TDI (possible range, −12 to +12 units) indicated decreased dyspnea associated with day-to-day functioning in a controlled study of outpatient pulmonary rehabilitation (5). In that same study, rehabilitation was also associated with decreased exertional dyspnea measured by the visual analog scale (74 to 51% of line length) recorded at maximal work rate during incremental testing. Other studies have shown significant postrehabilitation decreases in questionnaire-rated dyspnea associated with activities of daily living (6) and decreased levels of perceived breathlessness during stationary cycle exercise at work loads similar to baseline levels (9).

Handicap. Improvements in health status (health-related quality of life) after pulmonary rehabilitation have been documented in several studies (4, 7, 10, 11). Inpatient pulmonary rehabilitation led to statistically significant improvements in the dyspnea, mastery, and emotional functioning components of the Chronic Respiratory Disease Questionnaire (CRDQ), a respiratory-specific health status instrument (4). Other studies have also demonstrated improvements in health status (measured by the CRDQ) after comprehensive outpatient (10, 11) and home-based (7) pulmonary rehabilitation.

Survival. In the only randomized, controlled trial of pulmonary rehabilitation that included survival as an outcome measure, 67% of the rehabilitation versus 56% of education-treated control patients were alive at 6 yr (Figure 3) (6). This difference, however, was not statistically significant (p = 0.3), possibly because of the lack of power to detect a survival advantage.

Economics. Controlled trials have shown a trend toward a decrease in the use of health care resources after rehabilitation (18, 19), including a reduction in the number of hospitalizations and the number of hospital days for pulmonary- related illness (6, 20-22). For example, rehabilitation groups tended to have fewer hospital days after rehabilitation (−2.4 ± 15.4 versus +1.3 ± 10.7 d at 12 mo, compared with education-only treatment (6.4 ± 12.6 versus 3.6 ± 6.6 d, p = 0.2) (6).

Patients with chronic obstructive pulmonary disease (COPD) are frequent utilizers of health care resources, and a reduction in the number of hospitalization days per patient after rehabilitation has been noted in uncontrolled studies (23, 24). Pulmonary rehabilitation may also lead to reductions in the utilization of other health care resources such as visits to the emergency department or a physician's office and phone calls to the physician's office (25, 26). Preliminary evidence suggests that these benefits may result in an ongoing decrease in the number of hospitalization days required for COPD-related causes (27).

One concern regarding these studies is that each was conducted prior to the institution of managed care. More recent evidence suggests that resource utilization for patients undergoing rehabilitation in a health maintenance organization is significantly decreased during the year after completion of the program (28). Thus, the beneficial effects of pulmonary rehabilitation, from a health care utilization viewpoint in both the inpatient and the outpatient settings, are becoming recognized in an era of managed health care. More clinical trials are necessary, however, to evaluate these benefits.

Patient Selection and Assessment

Selection criteria. Pulmonary rehabilitation is indicated for patients with chronic respiratory impairment who, despite optimal medical management, are dyspneic, have reduced exercise tolerance, or experience a restriction in activities. It should be emphasized that symptoms, disability, and handicap, not the severity of physiologic impairment of the lungs, dictate the need for pulmonary rehabilitation. Thus, there are no specific pulmonary function criteria indicating the need for pulmonary rehabilitation. Unfortunately, in the United States, referral to pulmonary rehabilitation is too often reserved for those with far-advanced lung disease. Although these patients still stand to benefit considerably from pulmonary rehabilitation (29), referral at an earlier stage would allow for earlier preventative strategies such as smoking cessation, greater latitude in the exercise prescription, and, perhaps, better long-term adherence with maintenance exercise. Common indications for pulmonary rehabilitation relate to the handicap resulting from chronic respiratory disease (Table 3).

Table 3. COMMON INDICATIONS FOR REFERRAL FOR PULMONARY REHABILITATION

Respiratory disease resulting in:
 • Anxiety engaging in activities
 • Breathlessness with activities
 • Limitations with:
  – Social activities
  – Leisure activities
  – Indoor and/or outdoor chores
  – Basic or instrumental activities of daily living
 • Loss of independence

Because pulmonary rehabilitation has traditionally dealt with patients with COPD, the effectiveness of this therapy for pulmonary conditions other than COPD has received less attention (30). Although COPD remains the major referral base, patients with other conditions (Table 4) may be appropriate candidates for pulmonary rehabilitation because the same principles of ameliorating secondary morbidity also apply. By necessity, programs for patients without COPD may differ in educational focus and exercise prescription from traditional rehabilitation for those with COPD. For instance, education for the asthmatic patient emphasizes environmental issues such as recognizing and avoiding triggers and the need for use of controller medication, whereas exercise training intensity of patients with interstitial lung disease may require modification because of exercise-induced hypoxemia.

Table 4. NON-COPD INDICATIONS FOR PULMONARY REHABILITATION

• Asthma (193, 194)
• Chest wall disease (20, 195)
• Cystic fibrosis (196, 197)
• Interstitial lung disease, including post-ARDS pulmonary fibrosis (30, 152)
• Lung cancer (198, 199)
• Selected neuromuscular diseases (152, 200, 201)
• Perioperative states (e.g., thoracic, abdominal surgery)
• Postpolio syndrome (202, 203, 204)
• Prelung and postlung transplantation (205, 206)
• Prelung and postlung volume reduction surgery (207, 208)

Exclusion criteria for pulmonary rehabilitation fall into two broad categories: (1) conditions that might interfere with the patient undergoing the rehabilitative process and (2) conditions that might place the patient at undue risk during exercise training. Co-morbidities such as advanced arthritis, the inability to learn, or disruptive behavior are examples of the former, whereas severe pulmonary hypertension, unstable angina, or recent myocardial infarction are examples of the latter. However, even in those unable to fully participate in an exercise training program, education, psychosocial, and/or nutritional interventions alone may be of benefit. Patients who are poorly motivated are not ideal candidates for pulmonary rehabilitation; however, their level of motivation may change if they attend rehabilitation sessions. Finally, although including current cigarette smokers in a pulmonary rehabilitation program remains a subject of debate, it is reasonable to consider enrolling these individuals, particularly if they are participating actively in a smoking cessation program.

Assessment. Comprehensive assessment of the rehabilitation candidate is necessary for the development of an appropriate, individualized plan of care. The clinical history, physical examination, and review of pertinent records (e.g., spirometry) are necessary to determine the severity of respiratory impairment and to assess for other significant morbidity. An educational assessment by the rehabilitation staff determines the patient's knowledge base and learning needs and helps focus the educational intervention. A determination of baseline exercise capacity using incremental exercise testing is important in formulating the initial exercise training prescription, in detecting cardiac abnormalities associated with exercise, and in evaluating for hypoxemia during exercise. Other assessments that may be performed include: measurements of respiratory muscle strength such as maximum inspiratory and expiratory pressures, measures of peripheral muscle strength, assessments of activities of daily living, health status, cognitive function, emotional and mood state, and nutritional status/ body composition.

Assessment of cognitive function should be considered in patients with suspected memory problems since a limitation might impede rehabilitation efforts by interfering with the patient's ability to follow instructions or articulate his or her health status. Cognitive deficits, which may result from aging, dementia, hypoxemia (31, 32), or substance abuse, can be evaluated using one of several easy to administer instruments (33) such as the Mini-Mental State Exam (MMSE) (34) or the Neurobehavioral Cognitive Status Examination (NCSE) (35). These questionnaires screen for general factors such as memory, alertness, attention, orientation, and reasoning. Normative values for patients with COPD are available for the MMSE (36).

Because of the prevalence of symptoms related to anxiety and depression in patients with advanced lung disease (34, 37– 40), questionnaires may be used to screen for potential pathology. Alternatively, anxiety and depression can be assessed prerehabilitation and postrehabilitation as an outcome measure. Evaluation for the presence of emotional disturbances may be included as an integral part of the program or may be implemented on a case-by-case basis. High levels of anxiety or clinically significant depression may lead to difficulty in assimilating the educational components of rehabilitation since memory and attention are affected by these disorders (41). Emotional disturbances may also limit motivation or interfere with the ability to perform exercise training. Just as physiologically unstable patients must be stabilized prior to entering the rehabilitation program, so too should those with significant emotional disorders be treated and stabilized.

Many mood questionnaires are heavily biased toward assessing activity levels and other somatic factors such as sleep, eating patterns, and energy levels—areas also affected by physiologic changes from respiratory disease (42). Therefore, questionnaires relying primarily on cognitive changes may be more appropriate for pulmonary patients. The following questionnaires are commonly used in pulmonary patients, but they vary in the degree to which they measure cognitive changes. Questionnaires commonly used to measure coping and mood include the Psychosocial Adjustment to Illness Scale-Self Report (43, 44) and the Profile of Mood States (45). Questionnaires more specific to symptoms of depression and/or anxiety include the Geriatric Depression Scale (46), the Center for Epidemiological Studies–Depression Scale (47), the Hospital Anxiety and Depression Scale (48), the Self-Rating Depression Scale (49), the Beck Depression Inventory (50), and the State and Trait Anxiety Inventory (51).

Nutritional assessment is important since disturbances in body weight, body composition, and changes in eating habits are common in patients with advanced COPD (52, 53). Body weight can be assessed as a percentage of ideal body weight (the latter often obtained from insurance tables) or as the body-mass index (in units of kilograms per meters squared). Decreased weight is associated with decreased exercise performance (54), reduced muscle aerobic capacity (55), and increased mortality, independent of lung function in patients with advanced COPD (56). Body composition can be evaluated using anthropometry or bioelectrical impedance analysis, which estimate fat-free mass, or dual energy X-ray absorptiometry (DEXA), which estimates lean mass. Substantial reductions in fat-free or lean body mass, which, in part, reflect the impact of advanced pulmonary disease on peripheral musculature, may be present in patients of normal weight (52, 57). Alterations in body composition are correlated with impaired performance on timed walk testing and poorer health status, independent of body weight (54, 57).

Benefits Across Settings: Inpatient, Outpatient, and Home-based Pulmonary Rehabilitation

Despite substantial variability in program structure, pulmonary rehabilitation performed in inpatient (4), outpatient (5, 6, 10, 11), or home settings (8, 9) has documented clinical efficacy. Although little data exist directly comparing patient outcomes in different settings, it is probably the structure and components of the program rather than the setting itself that determine the effectiveness of pulmonary rehabilitation (9).

Pulmonary rehabilitation by setting may vary considerably in staff availability, program duration, structure, and individual components. The choice of setting often depends on the prerehabilitation physical, functional and psychosocial status of the patient, the availability and distance to the program, insurance payer stipulations, and patient preference. The advantages and disadvantages of pulmonary rehabilitation in outpatient, inpatient, and home-based settings are listed in Table 5. Inpatient rehabilitation is generally best-suited for the sickest patients, reflecting its intensive rehabilitative services and specialized training of the patient and/or family. Outpatient rehabilitation, which can be hospital-based or community-based, is currently the most widely available and, as such, has the potential to benefit the most patients. A certain level of functional ability, however, must already be present for patients to physically attend outpatient sessions two to three times a week (11).

Table 5. ADVANTAGES AND DISADVANTAGES OF PULMONARY REHABILITATION IN DIFFERENT SETTINGS

AdvantagesDisadvantages
InpatientCloser medical monitoring makes it ideal  for sickest patients with the greatest  functional deficitsCost and potential difficulty with  insurance coverage
Intensive nursing care available 24 h/dNot suitable for patients with less  severe respiratory or comorbid  disease
Transportation to and from the program  is not an issue for patientTransportation potentially difficult for  family members
Allows participation and observation of  family members in therapies
Ideal setting for patients requiring  assistive devices, tracheostomy care, or  ventilator weaning
OutpatientWidely availablePotential transportation issues
Least costlyNo opportunity to observe home  activities
Efficient use of staff resources
Least intrusive to the family
Home-basedConvenience to the patientCost and potential difficulty with  insurance coverage
Transportation not an issue for patient  unless frequent trips to a health-care  provider are part of the programLack of group support
Adaptation of exercise to a familiar  environment may lead to better  adherence with long-term treatment  goalsPotential lack of full spectrum of  multidisciplinary health personnel
Limited access to exercise equipment

The concept of home-based pulmonary rehabilitation may vary considerably among programs. For example, a home-based program may provide regular supervised home exercise and education given by physiotherapists for patients too dyspneic to attend outpatient rehabilitation (11). Alternatively, a program may include daily stationary bicycle exercise at home taught by a physical therapist, combined with twice-weekly visits to a local physiotherapist for additional training, regular home visits by a nurse, and monthly visits to a general practitioner (8). Patients attending the latter type of program would be considered as candidates for outpatient pulmonary rehabilitation programs elsewhere. The principal advantages of home- based rehabilitation are convenience for the patient and family members and a familiar environment for training and the acquisition of techniques. Although not well studied, the latter may promote sustained motivation with continued exercise training after completion of the formal program (9). Despite its convenience, home-based pulmonary rehabilitation may not be the ideal site for severely disabled patients since one recent study was unable to demonstrate significant improvements in exercise ability or quality of life in patients with severe dyspnea who were given rehabilitation at home (11).

Comprehensive pulmonary rehabilitation programs generally have four major components: exercise training, education, psychosocial/behavioral intervention, and outcome assessment. These interventions are generally provided by a multidisciplinary team that varies among programs but often includes physicians, nurses, respiratory therapists, physical therapists, occupational therapists, psychologists, and social workers. Although exercise training is the only component demonstrated in controlled clinical trials to enhance outcomes, the pervasive nature of the functional deficits in the typical patient suggests that a comprehensive approach would be optimal.

Exercise Training

Exercise training is the foundation of pulmonary rehabilitation. Although exercise has to date not resulted in measurable effects on the underlying respiratory impairment, its positive effects on dyspnea (Figure 1) underscores the importance of physical deconditioning as a co-morbid factor in advanced lung disease. Exercise training is based on general principles of exercise physiology: intensity, specificity, and reversibility (58).

Training intensity. In healthy subjects, aerobic training is usually targeted at 60 to 90% of the predicted maximal heart rate or 50 to 80% of the maximal oxygen uptake. This level is sustained for 20 to 45 min and repeated three to four times a week. Training at this intensity, which is usually well above the anaerobic threshold, increases maximal exercise performance, causes physiologic adaptations in peripheral muscles, and improves cardiac function in healthy subjects (59).

Until recently, the prevailing thought has been that patients with advanced lung disease (such as COPD) have a ventilatory limitation that precludes the aerobic training levels necessary for beneficial physiologic adaptations (60). The training intensity in earlier studies, however, was often well below the level of maximal work rate. Recent studies have demonstrated that anaerobic metabolism and an early onset of lactic acidosis can be observed in exercise training of patients with COPD (61, 62). Furthermore, greater improvements in maximal and submaximal exercise responses can be obtained after exercise training at high (60% of maximal work rate, above the anaerobic threshold) compared with low (30% of maximal work rate) exercise levels (61). Increases in oxidative enzymes in the peripheral muscles have been found after strenuous (63), but not low intensity, training (60). The reduction in ventilation and lactate levels at identical submaximal work rates after high-intensity exercise training strongly suggests that aerobic metabolism is indeed attainable in many patients with COPD (61). Training respiratory patients at 60 to 75% of maximal work rate results in substantial increases in maximal exercise capacity and reductions in ventilation and lactate levels at identical exercise work rates (63, 64).

Most pulmonary rehabilitation programs emphasize endurance training, utilizing periods of sustained exercise for about 20 to 30 min two to five times a week. Although training at levels of 60% of the maximal work load for prolonged periods of time is possible for a considerable proportion of patients with severe airway obstruction (6, 61), some cannot tolerate training at this intensity (63, 64). In these patients, interval training, consisting of two to three min of high-intensity (60 to 80% maximal exercise capacity) training alternating with equal periods of rest, might be an alternative. In healthy subjects, interval training elicits training effects similar to those of endurance training (65, 66), but to date, its role in patients with lung disease is unclear (67).

On the basis of available research, the target level of exercise training intensity should be a percentage of the maximum work capacity, e.g., 60% of the maximal oxygen consumption. In many centers, a percentage of the maximum heart rate is used to estimate this training intensity. Additionally, changes in heart rate can be used to study cardiac adaptations after exercise training in patients with COPD (61, 63, 68). The relationship between heart rate and work rate, however, varies widely among subjects (69) and may be affected by cardiac and lung disease or their therapy (70). Despite these limitations, heart rate measured at a given percentage of peak work rate is a reasonable parameter to set future training intensity. Alternatively, dyspnea ratings during maximal graded exercise testing may reliably predict specific exercise intensities during training (71), making symptom-guided exercise training a possible alternative to heart rate–guided training (72, 73).

Training specificity. Training specificity refers to the observation that benefit is gained only in those activities involving the muscle groups that are specifically trained. For instance, an increase in the 6-min walk distance (6MWD) occurs with lower extremity training but not with upper extremity training (74). There is, however, some transfer effect to other activities since cycle ergometer training improves walking distance (75) and vice versa. Because of training specificity, exercise programs should provide training that parallels the desired outcome(s) as closely as possible.

Upper extremity endurance training. Endurance training of the upper extremities to improve arm function is particularly important since many activities of daily living involve use of the arms. Training can be accomplished using supported arm exercises with ergometry or unsupported arm exercises by lifting free weights, dowels and stretching elastic bands. Both methods can effectively improve arm endurance (76).

Lower extremity endurance training. Most pulmonary rehabilitation programs emphasize training of lower extremities using singly or in combination stationary cycle exercise, treadmill walking, or ground-based walking. As stated earlier, not only is there a considerable increase in submaximal endurance time with lower extremity training of patients with COPD, there is also a dose-response effect: higher intensity exercise (60 to 80% of the maximal work rate) increases endurance time more than does lower intensity exercise (30% of the maximal work rate) (61). Other studies of cycle ergometer training (77, 78), treadmill walking (4, 6, 65), or combined walking and cycling (72) have also shown improvements in maximal work rate and endurance time.

Strength training. Because peripheral muscle weakness contributes to exercise limitation in patients with lung disease (79), strength training is a rational component of exercise training during pulmonary rehabilitation. To date, relatively few studies have evaluated the effectiveness of strength training in patients with lung disease, so its role in pulmonary rehabilitation remains to be defined. However, two randomized controlled studies suggest it may be an important component to exercise training. A trial of weight lifting as an exercise for respiratory patients showed that the group that exercised with loads ranging from 50 to 85% of the one-repetition maximum had a greater increase in peripheral muscle function than did an untreated control group (80). Although there was no concomitant increase in maximal endurance exercise capacity, there was a measured improvement in quality of life.

In a trial of a low-intensity (i.e., no additional loads) leg and arm muscle conditioning compared with an untreated control group (81), the treatment group increased their walk distance and had physiologic adaptation to exercise manifested by a reduced ventilatory equivalent for oxygen and carbon dioxide. No changes in maximal exercise performance were present. These positive results are somewhat surprising since in other studies low intensity exercise was not very effective (61).

Respiratory muscle training. Inspiratory muscle function may be compromised in COPD, an impairment that may contribute to dyspnea (82), exercise limitation (83), and hypercapnia (84). Respiratory muscle strength is commonly estimated by measuring maximal negative inspiratory pressure (Pimax) (85), although this is a highly effort-dependent test. Inspiratory muscle training is generally initiated at low intensities then gradually increased to achieve 60 to 70% of Pimax. The minimal load required to achieve a training effect is 30% of the Pimax (86). Two methods of inspiratory muscle training most commonly used are threshold loading and resistive loading. With threshold loading the training load is independent of flow (87, 88), requiring the build up of negative pressure before flow occurs, and hence is inertive in nature. Threshold and resistive training effects have not been adequately compared.

Although inspiratory muscle training using adequate loads undoubtedly improves strength of the inspiratory muscles in patients with COPD (89-93), it remains unclear whether this results in decreases in symptoms, disability, or handicap. There is some evidence that improvement in inspiratory muscle strength in COPD is accompanied by decreased breathlessness and increased respiratory muscle endurance (79, 94), but the benefits of inspiratory muscle strength training are not well established (95). Further research is needed to identify optimal candidates and diseases for respiratory muscle training and clarify its benefits and role in pulmonary rehabilitation programs.

Training reversibility. The reversibility of training effects is well known (58, 96, 97). As with normal persons, the training effects in patients with chronic lung disease are maintained only so long as exercise is continued. A reduction in adherence with the maintenance exercise prescription given at the completion of the formal pulmonary rehabilitation probably explains to some degree the reductions in timed walk distance (98) and exercise endurance time (6) occurring months to years later.

In a trial evaluating the long-term effects of home rehabilitation (99), patients were randomized into three groups: a treatment group given 12 wk of pulmonary rehabilitation followed by visits to a physical therapist once a week for a total of 18 mo, another treatment group given the same formal rehabilitation but visited the physical therapist once a month for 18 mo, and a control group that received no rehabilitation at all but was followed for 18 mo. Although both rehabilitation groups showed significant increases in maximal cycle work rate and 6MWD postrehabilitation, this improvement was not sustained at 18 mo with either maintenance training frequency. There was an overall tendency for a decline in the 6MWD after 18 mo, but there were no significant differences between the two training frequencies. In another trial where patients completing formal rehabilitation were instructed to continue exercise training at home and to visit the program once a month, the gains made in treadmill exercise endurance diminished considerably by 12 mo (6).

Neither of the above studies reported details of adherence with the postrehabilitation exercise training. Thus, the optimal frequency and intensity of regular post-rehabilitation maintenance exercise training remains to be determined. Additionally, the role of short periods of supervised exercise training after exacerbations of respiratory disease with a goal of returning the patient to baseline performance is an untested alternative. Thus, although it is clear that efforts at improving long-term adherence with exercise training at home will be necessary for long-term effectiveness of pulmonary rehabilitation, further information from controlled trials is needed.

Education

Although the benefits directly attributable to the educational component of pulmonary rehabilitation have not been fully documented, education is now so integral to virtually all comprehensive pulmonary rehabilitation programs that its effect in isolation cannot be readily determined. Education encourages active participation in health care (100, 101), leads to a better understanding of the physical and psychologic changes that occur with chronic illness, and helps patients and their families explore ways to cope with those changes (102, 103). Through the educational process, patients can become more skilled at collaborative self-management and more adherent to their treatment plan (104).

Education can be provided in small groups or on an individual basis, depending on needs of the patient, the site, the resources, and the design of the rehabilitation program (105). In general, the educational needs of pulmonary rehabilitation participants are determined at the initial evaluation and are reassessed during the program. A number of standard topics are addressed in the educational sessions (Table 6) (106). Three topics frequently incorporated into pulmonary rehabilitation programs are breathing retraining, energy conservation, and proper use of medications (and treatments) will be described in further detail. The utility of including education on end-of-life planning will also be discussed because of the emerging recognition of its importance for patients with chronic lung disease.

Table 6. COMMON TOPICS ADDRESSED IN EDUCATIONAL COMPONENT

• Anatomy and physiology of the lung
• Pathophysiology of lung disease
• Airway management
• Breathing training strategies
• Energy conservation and work simplification techniques
• Medications
• Self-management skills
• Benefits of exercise and safety guidelines
• Oxygen therapy
• Environmental irritant avoidance
• Respiratory and chest therapy techniques
• Symptom management
• Psychological factors—coping, anxiety, panic control
• Stress management
• End of life planning
• Smoking cessation
• Travel/leisure/sexuality
• Nutrition

Breathing strategies. Some patients may benefit from the breathing strategies of pursed-lip and diaphragmatic breathing. Pursed-lip breathing involves a nasal inspiration followed by expiratory blowing against partially closed lips, avoiding forceful exhalation. This strategy is often unconsciously used by patients with COPD to enhance exercise tolerance during periods of dyspnea and increased ventilatory demand. Pursed- lip breathing does reduce respiratory rate, minute ventilation, and carbon dioxide level, and increases tidal volume, arterial oxygen pressure, and oxygen saturation (107-109). Despite these physiologic actions, the effectiveness of pursed-lip breathing in reducing dyspnea in COPD is controversial, with some studies actually demonstrating an increase in breathlessness at rest (110) and during exercise (111).

The strategy of diaphragmatic breathing is to consciously expand the abdominal wall during inspiratory diaphragm descent (112). In theory, this would increase the efficiency of the diaphragm while reducing the ineffective movements of the upper rib cage during ventilation of patients with COPD (113, 114). Despite an early study reporting an increase in diaphragm excursion with diaphragmatic breathing (115), later studies showed increases in overall chest wall motion asynchrony, abdominal paradox, reduced mechanical efficiency of the chest wall, and increased work of breathing with this maneuver (116-118) without improvement in the distribution of ventilation to the lung bases (119). Finally, diaphragmatic breathing was found to increase rather than decrease the level of dyspnea (118). In view of these results, the routine use of diaphragmatic breathing training in pulmonary rehabilitation is not recommended.

Energy conservation and work simplification. Principles of energy conservation and work simplification assist patients in maintaining activities of daily living such as self-care, home management, shopping, and performance of job-related tasks. Methods include paced breathing, which is based on principles of reducing breathholding and timing the respiratory cycle with physical activities, optimizing body mechanics, advanced planning, prioritization of activities, and the use of assistive devices. These techniques might help the patient conserve energy from basic daily activities to be used for leisure activities and socialization. In combination with exercise training, energy conservation techniques may make it possible for some patients with advanced disease to continue or even resume employment.

Medication and other therapies. Education in the types of medications, action, side effects, dosage, frequency, and proper use of all oral and inhaled respiratory medications should be provided in a comprehensive pulmonary rehabilitation program. Instruction in metered dose inhaler technique and spacer devices are particularly important since new modes of administration such as dry-powder inhalers evolve and deficiencies in technique are common in patients with chronic lung disease (120, 121). Not uncommonly, supplemental oxygen therapy is instituted at about the time patients are referred for pulmonary rehabilitation. Instruction on the indications and appropriate use of oxygen is often invaluable for both patients requiring oxygen as well as in preparation for those who may eventually require its use.

End-of-life education. The progressive nature of airflow limitation in patients with COPD presents a risk for respiratory failure that increases over time. Patients faced with an episode of respiratory failure need to decide (along with their families and clinician) if intubation and mechanical ventilation will provide life-saving support for a remedial episode of respiratory failure or will only delay the dying process at the terminal phase of their disease. Unfortunately, clinical factors assessable at the onset of respiratory failure caused by COPD are poor predictors of outcome from mechanical ventilation (122-125). The decision to initiate life-support, therefore, is not purely medical in nature. It requires patients to determine the acceptability of life-sustaining care by blending their physician's uncertain estimates of a meaningful recovery with their own personal values and life goals (126, 127). Unfortunately, most patients with chronic lung disease are poorly prepared to participate in this decision-making process because they have not discussed these issues with their health care provider during periods of stable health (129). Delaying these discussions until the terminal hospitalization provides a limited opportunity for patients to make informed decisions (129).

End-of-life education during pulmonary rehabilitation offers an opportunity to provide patients with an understanding of life-sustaining interventions and the importance of advance planning. Recent data indicate that 99% of patients enrolled in pulmonary rehabilitation desire a greater understanding of end-of-life care and they consider nonphysician educators within pulmonary rehabilitation to be as acceptable as physicians as sources for this information (129). Also, most patients prefer to receive advance planning information during periods of stable health in outpatient settings when their decision-making capacity is not impaired by acute complications of their disease (129). No investigations have examined the effectiveness of different curricular techniques within pulmonary rehabilitation for advance planning education, but one study indicates that video presentations, brochures, and group discussions that require minimal educator time can promote the adoption of advance directives and more frequent patient-physician communication on end-of-life care (130). Considering the high interest among pulmonary patients for advance planning information, greater incorporation of this topic within pulmonary rehabilitation curricula is needed considering that only 8% of programs in the United States now provide end-of-life education to their patients (131).

Psychosocial and Behavioral Intervention

Psychologic and behavioral problems such as anxiety, depression, difficulties in coping with chronic lung disease, and reductions in self-efficacy (the ability to cope with illness) contribute to the handicap of advanced respiratory disease (6, 132-134). Dyspnea has a prominent affective component (135), and fear of dyspnea-producing activities may further limit the patient's ability to participate in activities of daily living. Furthermore, the anxiety and decreased energy levels associated with chronic lung disease may affect the patient's self-efficacy. Reduced self-efficacy of the patient may also burden the spouse or caregivers with new or increased responsibility for bathing, dressing, and meal preparation (136).

Psychosocial and behavioral intervention in comprehensive pulmonary rehabilitation programs can be in the form of regular patient educational sessions or support groups focusing on specific problems such as stress management. Instruction in progressive muscle relaxation, stress reduction, and panic control may help reduce dyspnea and anxiety (137). Because of the effects of chronic respiratory disease on the family, participation of family members or friends in pulmonary rehabilitation support groups is encouraged. Informal discussions of common symptoms, concerns, and problems during rehabilitation sessions may lend emotional support to patients. Group therapy, which is occasionally offered in pulmonary rehabilitation programs, integrates many of the principles of coping and role transition. The usefulness of group therapy in pulmonary rehabilitation, however, is not established (138).

The effect of pulmonary rehabilitation on psychologic outcomes has not been clearly defined. Significant reductions in symptoms of depression and anxiety one month after pulmonary rehabilitation were observed in one noncontrolled study of pulmonary rehabilitation that, in addition to exercise training and educational topics five days a week, included group psychologic counseling and stress management sessions twice-weekly (139). On the other hand, no significant changes in depression were noted in a controlled, randomized trial of outpatient pulmonary rehabilitation (6). These studies, however, used different measures for evaluating depressive symptoms. Self-efficacy, which can be measured before and after pulmonary rehabilitation as an outcome variable (140-143), may increase with exercise training (144). Increases in self-efficacy for walking have been demonstrated after pulmonary rehabilitation (6).

Outcome Assessment

Outcome assessment has become an important component of comprehensive pulmonary rehabilitation both for determining individual patient responses and for evaluating the overall effectiveness of the program. Measurement of the individual's change in performance serves to reinforce the importance and magnitude of the gains made through the hard work of the patient, family, and staff. Evaluation of the program through standardized outcome measures determines the overall effectiveness of the program and serves as a tool for quality improvement. A variety of tests exist for measuring the disability and handicap (Table 7). Questionnaire measures of functional status, which fall somewhere between disability and handicap, are listed under handicap. Not listed are measures of psychological status, which are described earlier in this paper.

Table 7. COMMONLY USED OUTCOME MEASURES IN PULMONARY REHABILITATION

Outcome MeasuresImpairmentDisabilityHandicapSymptoms*
Exercise ability
 Incremental exercise tests
 Submaximal exercise tests
 Walking tests
General health status
 Sickness Impact Profile (SIP)
 Quality of Well Being Scale (QWB)
 Medical Outcomes Study, Short-Form 36 (SF-36)P
Respiratory-specific health status
 St. George's Respiratory Questionnaire (SGRQ)D
 Chronic Respiratory Disease Questionnaire (CRQ or CRDQ)F
Respiratory-specific functional status
 Pulmonary Functional Status and Dyspnea Questionnaire (PFSDQ) or D
  modified version (PFSDQ-M)D/F
 Pulmonary Functional Status Scale (PFSS)
Exertional dyspnea
 Visual analog scale rating during exercise testing (VAS)D/F/P
 Category rating (Borg) during exercise testingD/F/P
Overall dyspnea
 Medical Research Council Scale (MRC)
 Baseline and Transitional Dyspnea Indexes (BDI and TDI)

* Symptoms independently evaluated from activities designated as follows: D = dyspnea; F = fatigue; P = pain.

Measures of disability

Incremental exercise tests. Incremental exercise testing on a stationary bicycle or treadmill involves increasing work rate at regular intervals to maximal tolerance or to a heart rate of 85% of predicted maximum. Routine measurements include heart rate, respiratory rate, blood pressure, electrocardiogram, and oxygen saturation. Analysis of exhaled gases, available in some exercise laboratories, allows for the determination or calculation of minute ventilation, oxygen consumption, carbon dioxide production, anaerobic threshold, and dead space. Dyspnea or leg fatigue during exertion can be rated using a category scale or a visual analog scale. The effect of training on physiologic variables can be determined by measures such as the V˙e at maximum work rate or at identical submaximal levels before and after intervention. Incremental exercise testing, although often symptom-limited in chronic lung disease, is reproducible (145-148) and sensitive to improvements from pulmonary rehabilitation.

Submaximal exercise tests. Stationary cycle or treadmill exercise testing at a constant fraction of maximal work rate is frequently used to measure exercise endurance capacity in pulmonary rehabilitation (1, 3, 149). A longer exercise time on the cycle ergometer or treadmill indicates greater exercise endurance. This test, which is more effort-dependent than incremental exercise testing, is often extraordinarily responsive to pulmonary rehabilitation intervention, with postrehabilitation exercise endurance times considerably longer than corresponding baseline values (6). Endurance testing can also be used to show a reduction in ventilatory requirements for exercise after a period of exercise conditioning by demonstrating a decrease in minute ventilation at a given work rate (150).

Walking tests. Physical tests of disability may assess the patient's ability to perform specific activities of daily living such as walking. In the pulmonary rehabilitation setting, the six- and 12-min walking tests and the Shuttle Walking Test are conducted for this purpose. The timed walk tests are typically conducted under field testing conditions and are less reproducible than tests conducted under more highly controlled conditions (151). For the timed walk tests, patients are instructed to walk as far as possible in a corridor or large room at his/her own pace during the allotted period of time. These tests are simple to perform, well-tolerated, and relevant to many daily activities. Patients with COPD demonstrate significant learning effects for both of the timed walk tests, especially when they are repeated over relatively short intervals (152-157). Timed walk tests correlate with peak exercise performance on graded exercise tests (119, 158, 159) and self-reported data on functional status questionnaires (124, 160). One study has suggested that the minimal clinically meaningful increase in the 6MWD is about 54 m (16). As with other tests of physical performance, the testing conditions must be standardized. Encouragement and coaching strategies can significantly influence performance and should be standardized from test to test (155).

The progressive 10-m Shuttle Walking Test is an externally paced measure of exercise capacity designed for individuals with COPD. The patient must walk up and down a 10-m distance (shuttle) at gradually increasing speeds. Walking speed, dictated by a beeping signal, is increased after every minute of walking by shortening the time between signals. The Shuttle Walking test is similar to the timed walk test in that it is a field test where distance walked is the outcome measure (161); however, it differs in two aspects. First, it is incremental in nature and therefore more a measure of exercise capacity than of endurance. Second, since the external signal sets the pace, self-pacing (which is of considerable importance to the timed walk) is eliminated. The shuttle walk is reproducible (162) and correlates well with maximum oxygen consumption during incremental treadmill exercise (r = 0.88) (163). However, it has not yet been extensively used as an outcome measure for pulmonary rehabilitation. A recent study has suggested it is highly responsive to therapeutic intervention (11).

Exertional and overall dyspnea. Dyspnea is the most common symptom of individuals with chronic pulmonary disease, and is frequently the major reason for seeking emergent care (164). Exertional dyspnea can be directly rated during a specific activity such as treadmill exercise or timed walking tests. Overall, dyspnea can be assessed by determining its effects on day-to-day activities.

Dyspnea during exercise is usually measured with a category scale such as the Borg scale (165) of perceived exertion or a visual analog scale (VAS) (166). Using the Borg scale, breathlessness is rated by selecting a number corresponding to a verbal descriptor. Descriptors usually range from no breathlessness (zero) to maximal breathlessness (10). The VAS measures breathlessness by having the patient point along a vertical line, which is 100 mm in length and anchored at either end with descriptors such as “greatest breathlessness” and “no breathlessness.” The distance from the beginning of the line to the point noted by the patient represents the level of dyspnea.

The effect of dyspnea on functional status or daily activities can be measured with instruments such as the Medical Research Council (MRC) dyspnea questionnaire, the University of California San Diego Shortness of Breath Questionnaire (UCSD-SOBQ) (167, 168), the dyspnea component of the Chronic Respiratory Disease Questionnaire (4, 169), the Baseline and Transitional Dyspnea Indexes (BDI and TDI) (13), and the Pulmonary Functional Status and Dyspnea Questionnaire (PFSDQ) (170) and its modified version (PFSDQ-M) (171). The dyspnea component of the Chronic Respiratory Disease Questionnaire evaluates the impact of dyspnea on five activities chosen by the patient to be important. The BDI measures disturbances in function, effort, and task resulting from dyspnea, whereas the TDI measures changes in these areas over time. The PFSDQ and PFSDQ-M evaluate general dyspnea as well as dyspnea related to specific functional activities.

A study evaluating the impact of exercise training on dyspnea of individuals with COPD illustrates the usefulness of exertional and general dyspnea ratings as outcome measures (72). Thirty patients given 6 wk of supervised multimodality exercise training were compared with an equal number of untreated control subjects. Dyspnea and fatigue, measured with a Borg scale during graded cycle exercise, decreased significantly in the treatment group. The relief in dyspnea correlated with a fall in ventilatory demand during exercise, indicating a training effect from the exercise. The exercise training group also had decreased chronic dyspnea, with the TDI increasing by 2.8 units compared with no change in the untreated control group.

Measures of handicap

Health status (health-related quality of life). Pulmonary rehabilitation incorporates a variety of interventions to produce improvements in symptoms, disability, and handicap. Although it is possible to make specific measurements of each of these domains, there is a need for an overall summary measure of benefit. Health status instruments can provide such a measure (172). There is evidence that the correlation between improved physiologic functioning and the patient's perception of improved overall health is very weak (173), thus gains in health must be measured directly and not inferred from other measures. After rehabilitation, the improvement in the patients' sense of mastery is equal to the improvement in their dyspnea associated with daily activities (14). It is necessary, therefore, to quantify the psychologic improvement as well as the physical function gains after rehabilitation.

Quality of life has been described as a person's satisfaction or happiness with life in domains he or she considers important (174, 175). Given this framework, quality of life may be thought of as a balance between that which is desired in life and that which is achieved or achievable. This applies very well to an individual, but valid measurements of an individual's quality of life are difficult to make and have limited utility since, by definition, measures cannot be standardized and applied to all populations of patients. Despite difficulties in measurement, the concept of quality of life is very useful because it fits with an approach to rehabilitation in which areas of impaired life may be identified for each patient.

Health status, or health-related quality of life, has a more restricted measurement focus than quality of life. It pertains only to the domains of life insofar as they affect (or are affected) by “health.” Three main types of health status measurement have been used in pulmonary rehabilitation: utility scales such as the Quality of Well Being Scale (176), general health questionnaires such as the Sickness Impact Profile and the Medical Outcomes Study Short Form-36 (SF-36) (177, 178), and disease-specific scales such as the Chronic Respiratory Disease Questionnaire (CRDQ) (169) and the St. George's Respiratory Questionnaire (SGRQ) (172). The reader is referred to the American Thoracic Society's Web page for a description of these instruments in greater detail (175). There is evidence that all three types of measures have the ability to discriminate between different levels of impaired health among patients. However, the disease-specific measures have better evaluative properties, i.e., demonstrate greater sensitivity to change from baseline after rehabilitation intervention (3, 7, 11).

Health status measures have two major applications in the context of pulmonary rehabilitation: quantifying the benefit of programs (4) and measuring the effectiveness of new methodologies in clinical trials (179). Currently, there is little experience in the use of such measures to assess the benefits in individual patients.

Respiratory-specific functional status. Functional status can be described as having four dimensions: capacity, performance, reserve, and capacity utilization (180). Functional capacity is what the patient is capable of doing, whereas functional performance is what the patient actually does on a day-to-day basis. Functional reserve is the difference between capacity and performance, called upon in time of need. Treatment of pulmonary patients (including rehabilitation) serves to increase this reserve, allowing patients greater ability to engage in daily activities. Whether the patient takes advantage of this “reserve” is an individual choice, which may account for the variability in performance among patients postrehabilitation. Functional capacity utilization refers to how closely performance approaches the patient's functional capacity.

Functional performance evaluation in respiratory disease focuses on the individual's ability to perform activities of daily living (181). Activities of daily living can be divided into basic activities such as eating, bathing, or dressing, and instrumental (higher level) activities, which are needed to adapt independently to the environment such as walking outdoors, or shopping (182). The impact of respiratory disease on these activities varies. Dyspnea may be associated with otherwise normal levels of activities, the activity may be limited because of dyspnea or fatigue, or the activity may be eliminated altogether because of these symptoms.

Functional status is usually measured by a questionnaire and, thus, is a self-report of functional performance. Several questionnaires have been used successfully in pulmonary rehabilitation (Table 7) (170, 171, 183). These provide an estimate of the impact of the program on various activities, recognizing that the results are limited by patient motivation, recall, and perception of improvement.

Which outcome measures to choose and when to measure them. Measurement of outcomes should be incorporated into every comprehensive pulmonary rehabilitation program. The extent of assessment will depend on the purpose of the measurement, the goals of the program, and the resources and level of clinician expertise. Minimal requirements include prerehabilitation and postrehabilitation assessment of: (1) dyspnea, (2) exercise ability, (3) health status, and (4) activity levels (if this is not sufficiently evaluated by the health status questionnaire). The zeal to capture all outcome areas must be tempered by the realization that these assessments require considerable staff time and can be burdensome to the patient. Although prerehabilitation to immediately postrehabilitation changes are of importance, the long-term maintenance of the gains in the various outcome areas should also be a concern. Accordingly, consideration should be given to follow-up measurements at longer periods of time such as 6 and/or 12 mo, if feasible.

Despite the progress made in understanding pulmonary rehabilitation as outlined in this document, more information is needed to ensure appropriate treatment for the ever-increasing number of patients with chronic respiratory disease. The following are several areas recommended for study or research as the field of pulmonary rehabilitation continues to evolve.

A Consensus on Terminology

Unfortunately, there is confusion in the terminology used in pulmonary rehabilitation for patient outcomes, and a more unified phraseology would be of benefit. This Committee has adopted the World Health Organization's International Classification of Impairments, Disabilities, and Handicaps. Although this classification is by no means perfectly suited to respiratory disease and pulmonary rehabilitation, use of these terms would place pulmonary rehabilitation in line with other rehabilitation disciplines.

The Effect of Pulmonary Rehabilitation on Health Care Cost and Survival

Although pulmonary rehabilitation makes patients exercise more and feel better, two important outcomes lacking study are the impact on health care costs and survival. As described earlier, much of the current evidence is based on historical data. Scientifically sound, controlled studies in both areas are needed.

The Essential Components of the Pulmonary Rehabilitation Program

Is the whole of rehabilitation greater than the sum of its parts? There is no question that exercise training is an important component of pulmonary rehabilitation. However, little is known about the additional benefit of education, breathing retraining strategies, psychosocial support, and group therapy. Knowledge of the effectiveness of individual components would be beneficial for patients who cannot exercise because of their medical condition. This would include patients requiring mechanical ventilation, experiencing physical limitations, or severe systemic illness.

The Exercise Prescription

More remains to be learned regarding the intensity, duration, and optimum form of exercise training for individuals with lung disease, if indeed one exists for this heterogeneous population. The effect of exercise training is dose-dependent with high intensity training causing greater physiologic adaptation than low-intensity training. But does grueling exercise at 80% or so of maximum work load translate into better quality of life? Might this impact negatively on long-term adherence with exercise? Is the relatively little-studied strength training approach a reasonable alternative? Likewise, the best type of upper extremity training is unknown. The best application of ventilatory muscle training, if one exists, also is an area where additional research is warranted.

Respiratory Muscle Rest

The training of athletes incorporates both periods of increased physical load and periods of relative rest. This concept has not been fully explored in patients with respiratory diseases. We know that patients with ventilatory failure of neuromuscular origin are helped by noninvasive positive-pressure (NPPV) mechanical ventilation. We have also learned that patients with COPD who develop acute-on-chronic respiratory decompensation may benefit from NPPV (184-186). Even though the results have not been totally encouraging, there remains an interesting hypothesis that needs exploration. Perhaps selected patients with stable, but advanced COPD, NPPV could be used to help patients exercise more.

Methods of Improving Long-term Adherence with Exercise Training

Pulmonary rehabilitation has been viewed as having three phases: gains made during the formal program, the transfer of these gains into physical performance, and maintenance of these gains over time (187). Studies evaluating the long-term effectiveness of pulmonary rehabilitation have generally shown a gradual decrease in gains made in disability and handicap over time. Some of this decline undoubtedly reflects the progression of the underlying respiratory disease or co-morbidity; however, can this progression be slowed with maintenance exercise programs?

Pulmonary Rehabilitation and Surgery

Lung volume reduction surgery has been shown to be useful for selected patients with pulmonary emphysema. Pulmonary rehabilitation is commonly offered before lung volume reduction surgery and, indeed, has been established as the standard of care for participants in the National Emphysema Treatment Trials (188). Additionally, its application is universal in lung transplantation programs. A valid extrapolation would be that preoperative pulmonary rehabilitation might benefit patients with lung disease preparing for any major surgical procedure.

Simplifying Outcomes

It has been traditional to rely on physiologic measures such as pulmonary function to monitor the effect of medical therapy. Although this has served us well in asthma and in measuring the effects of lung surgery, pulmonary function is poorly correlated with dyspnea, health status, or health care utilization. As described in this document, questionnaires have been developed to evaluate these outcomes. Too often, the questionnaires are long, difficult to administer, or complex to score. In today's era of cost containment and increased productivity, it is difficult and perhaps unfair to ask health care providers to incorporate these tools into the everyday management of patients. Simplifying or minimizing the current tools without losing their discriminative capability or ability to detect change with intervention would be most beneficial.

Patients Not Selected for Pulmonary Rehabilitation

By necessity, the outcomes measured in pulmonary rehabilitation are those of patients attending the programs. Very little is known about potential candidates who were either rejected for rehabilitation or for other reasons did not participate in the program. For example, one study reported screening 235 patients to eventually recruit approximately 80 participants (4). In other words, more patients failed to participate than completed the program. Who are these patients? What were the reasons for their exclusion from pulmonary rehabilitation? Do the findings presented in this Statement extend to all patients? How do we select the best candidates so that patient and staff time is best utilized?

Rehabilitation of the non-COPD and Pediatric Patient

Although anecdotal information supports its use, little scientific information is available on the effectiveness of pulmonary rehabilitation in diseases other than COPD and asthma, and little experience is available in the pediatric patient. Do patients with pulmonary fibrosis or chest wall disease improve with pulmonary rehabilitation? What special interventions are necessary for these patients? What components of standard programs would benefit the pediatric patient? How does family support affect the rehabilitation of pediatric patients?

Should Cigarette Smokers be Enrolled in Pulmonary Rehabilitation Programs?

Patients with COPD who continue to smoke cigarettes are often most in need of pulmonary rehabilitation, but there is no consensus on whether they should be included in pulmonary rehabilitation programs. Is their inability or unwillingness to quit smoking a predictor of failure in rehabilitation or is it simply another aspect of co-morbidity that must be addressed?

Which Factors Predict Improvement with Pulmonary Rehabilitation?

A review of the controlled studies of pulmonary rehabilitation would indicate that the degree of improvement with this intervention varies considerably among patients. Furthermore, improvements in health status do not necessarily follow increases in exercise ability (189). Might it be possible from the initial assessment to predict which patients are likely to improve with therapy?

Summary

The evidence presented in this and previous position papers (190-192) show that comprehensive pulmonary rehabilitation is an improvement over standard medical management or educational intervention alone in several outcome areas. The benefits achieved extend beyond increases in exercise ability and include decreases in dyspnea and improvements in health status.

Committee Members developing the Statement on Pulmonary Rehabilitation were:

Suzanne C. Lareau, R.N., M.S. (Co-chair)

Richard ZuWallack, M.D. (Co-chair)

Brian Carlin, M.D.

Bartolome Celli, M.D.

Bonnie Fahy, R.N., M.N.

Rik Gosselink, Ph.D., P.T.

Paul Jones, Ph.D., M.D.

Janet L. Larson, R.N., Ph.D.

Paula Meek, R.N., Ph.D.

Carolyn Rochester, M.D.

Dawn Sassi-Dambron, R.N., B.S.N.

David Stubbing, M.B., B.S.

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