Pulmonary Rehabilitation

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Chapter 34 Pulmonary Rehabilitation

Principles

The most common form of lung disease in the United States is chronic obstructive pulmonary disease (COPD), primarily because of its link to smoking. In 2007 the American Cancer Society reported that 19.8% of adults 18 years of age or older were current smokers compared with 41.9% in 1965. Unfortunately, in 2006 it was reported that 20% of high school and 6.3% of middle school students smoked. COPD is very rare in nonsmokers, and the vast majority of the deaths from this disease can be attributed to cigarette smoking. Statistics regarding COPD are shown in Box 34-1.66

Restrictive pulmonary disease is most commonly caused by neuromuscular and orthopedic disorders, such as spinal cord injury (SCI) and scoliosis. According to statistics available from the National Spinal Cord Injury Association Resource Center, as of March 2009 there are an estimated 250,000 to 400,000 persons with an SCI or spinal cord dysfunction in the United States. Of these patients, 82% are male, 17.5% have complete tetraplegia, and 31.2% have incomplete tetraplegia. Duchenne muscular dystrophy (DMD) is one of the more common neuromuscular diseases that cause restrictive pulmonary dysfunction, with an incidence of 1 per 3600 male infants in the United States.

Pulmonary rehabilitation is defined as a multidisciplinary program that provides persons with the ability to adapt to their chronic lung disease.13 It includes physical conditioning, ongoing medical management, training in coping skills, and psychosocial support. Fear of dyspnea can lead to panic, which increases the work of breathing. Dyspnea also causes progressive inactivity, which further weakens the individual. Pulmonary rehabilitation addresses this fear and uses a greater tolerance of dyspnea to increase strength, endurance, and quality of life.

When advanced pulmonary impairment occurs, other treatment options, including mechanical ventilation, can be used. If the impairment is caused by intrinsic lung disease, partial lung resection (lung volume reduction surgery [LVRS]) and lung transplant might be helpful.

Treatment Options in Pulmonary Rehabilitation

Several treatment modalities are used in pulmonary rehabilitation. These include general medical management, oxygen therapy, chest physical therapy, exercise training, and nutritional and psychosocial support.

Oxygen Therapy

Long-term oxygen therapy (LTOT), provided more than 15 hr/day, improves survival and quality of life in COPD if hypoxemia is present with arterial oxygen saturation (SaO2) less than 88%. It can also increase exercise tolerance and cognitive outcomes.14 LTOT is also needed if the patient’s SaO2 is less than 89% and there is evidence of pulmonary hypertension or peripheral edema, suggesting congestive cardiac failure, or polycythemia.29

Oxygen concentrators have become the most popular method of providing oxygen in the home. Portable models are readily available and can be used with an AC or a DC inverter. Some models are as light as 6 lb, with the average weight ranging between 6 and 20 lb. Most models have batteries that can be recharged in as little as 2 hours and have battery running times as long as 6 hours. Portable concentrators can easily be carried on a pull cart or on the body with a shoulder strap or waist harness. Most units are able to deliver 1 to 6 L/min. Some companies have produced models that provide up to 8 L/min of oxygen and have two flowmeters so that two persons can use oxygen from the same concentrator if the total use is no more than 8 L/min. Other systems incorporate a refill station as part of the concentrator, so that portable oxygen cylinders can be filled over a couple of hours. An oxygen-conserving regulator allows the oxygen to last 4 times as long. An oxygen cylinder can now be safely mounted on a motorized wheelchair if the motors and batteries are sealed and both are covered by a rigid housing.

Chest Physical Therapy

A good understanding of pulmonary function tests (Table 34-1 and Figure 34-1), as well as the mechanics and work of breathing in normal and diseased states, is essential in planning an effective therapy program for persons with pulmonary disease.32 Breathing exercises begin with relaxation techniques, which then become the foundation for breathing retraining. Retraining techniques for persons with COPD include pursed lip breathing, head down and bending forward postures, slow deep breathing, and localized expansion exercises or segmental breathing. These techniques maintain positive airway pressure during exhalation and help reduce overinflation. Although diaphragmatic breathing is widely taught, it has been shown to increase the work of breathing and dyspnea compared with the natural pattern of breathing in the patient with COPD.13 The other component occasionally used to reduce fatigue is respiratory muscle endurance training, which usually concentrates on inspiratory resistance training. Training of the expiratory muscles, however, has also been found to be of some value.43

Airway clearance strategies are indicated for persons with (1) abnormal cough mechanics (e.g., muscle weakness), (2) altered mucus rheology (e.g., cystic fibrosis), (3) structural airway defects (e.g., bronchiectasis), and (4) altered mucociliary clearance (e.g., primary ciliary dyskinesia).42 Clearance of secretions is mandatory to reduce the work of breathing, improve gas exchange, and limit infection and atelectasis. For chest physical therapy to be effective, mucoactive medications must be given.62 These include expectorants, mucolytics, bronchodilators, surfactants, and mucoregulatory agents that reduce the volume of mucus secretion. Antitussives must be used for uncontrolled coughing, which can precipitate dynamic airway collapse, bronchospasm, or syncope.

Techniques for clearing secretions include postural drainage, manual or device-induced chest percussion and vibration, device-induced airway oscillation, incentive spirometry, and other devices and measures that improve the ability to cough. Head-down tilt positions for postural drainage should be used with caution in persons with severe heart disease.47 In a manually assisted cough, the patient’s abdomen is compressed while the patient controls the depth of inspiration and the timing of opening and closing the upper airway. Noninvasive intermittent positive-pressure ventilation (NIPPV) with air stacking or glossopharyngeal breathing (GPB) is used to increase the depth of inspiration when inspiratory muscles are too weak to produce a deep breath. Air stacking is holding a portion of two or more breaths to fully inflate the lungs before exhalation. In GPB, the person uses the tongue to breathe. The technique is described more fully later in this chapter. When an upper motor neuron lesion above the midthoracic level has paralyzed the abdominal muscles, functional electrical stimulation of these muscles can produce a cough.34

Positive expiratory pressure mask therapy followed by “huff coughing” is a useful technique when other methods of mobilizing secretions are not tolerated.39 Autogenic drainage is a secretion clearance technique that combines variable tidal breathing at three distinct lung volume levels, controlled expiratory airflow, and huff coughing. The CoughAssist Mechanical In-Exsufflator cough machine (Figure 34-2), manufactured by the Philips HealthCare Respironics (Murraysville, PA) provides deep inspiration through a face mask or mouthpiece, or with an adapter, to a patient’s endotracheal or tracheostomy tube, followed rapidly by controlled suction. It has been shown to provide highly effective secretion removal.4 The device must be used with caution and is contraindicated in patients with bullous emphysema or a history of pneumothorax or pneumomediastinum in the recent past, especially if they are the result of barotrauma.

Exercise Conditioning: General Considerations

Aerobic exercise is the backbone of any pulmonary rehabilitation program. The inclusion criteria for exercise in pulmonary rehabilitation are straightforward. A candidate must demonstrate a decrease in functional exercise capacity as a result of pulmonary disease and be able to participate safely in a rigorous cardiorespiratory endurance training program. Cardiopulmonary exercise testing is necessary for the selection and evaluation of individuals in several circumstances before exercise conditioning. Indications for cardiopulmonary exercise testing have been adopted by the American Thoracic Society and the American College of Chest Physicians (Box 34-2).77 The pulmonary disease should be relatively stable. Medical comorbidities that contraindicate exercise should be absent. Patients should not have orthopedic or cognitive disabilities that prevent exercise. Patients must be motivated to exercise on a consistent basis. Finally, patients should abstain from tobacco products.

Exercise Prescription for Pulmonary Rehabilitation

Exercise prescription guidelines are largely based on programs in which the majority of participants are patients with COPD. These guidelines, however, appear to be appropriate for patients who have other pulmonary diseases as well. Exertional dyspnea is among the most frequently experienced symptoms of pulmonary diseases and leads to physical disability and functional impairment. Cardiorespiratory exercise training is often effective for decreasing exertional dyspnea. Provided the cardiovascular, respiratory, and neuromuscular systems have adequate reserve to undergo a program of progressive exercise, skeletal muscles can develop an increased ability to sustain physical activity. After training, muscle oxygenation might be improved, which lowers blood lactate levels at any given level of strenuous exercise. The confluence of increased oxygen extraction by the muscles and lower blood lactate lessens carbon dioxide production and the ventilatory requirement for a given workload.

The American Thoracic Society,48 the American College of Chest Physicians,60 and the American College of Sports Medicine78 have provided recommendations for pulmonary rehabilitation exercise. In general, pulmonary rehabilitation exercise programs should include cardiorespiratory endurance training of larger muscle groups. Over-ground or treadmill walking is generally the preferred method because walking is a functional activity. Leg-cycling is an acceptable alternative. Arm-cycling can also be incorporated. Many patients, however, might have difficulty tolerating arm-cycling because of an increased ventilatory drive that could worsen the patient’s dyspnea during the activity. Resistance and flexibility exercises might also improve functional capacity in patients with pulmonary diseases. The most specific exercise prescription guidelines have been provided by the American College of Sports Medicine (Table 34-2).

Table 34-2 Summary of ACSM Guidelines for Exercise Prescription

Component Cardiorespiratory Endurance Training
Activity Dynamic exercise of large muscle groups
Mode Over-ground or treadmill walking
  Stationary leg-cycling or outdoor bicycling
  Stair climbing
Frequency 3-5 days/wk
Duration 20-60 min/session
Intensity 50%-85% heart rate reserve
  65%-90% maximum heart rate
  RPE = 12-16 (category scale)
  RPE = 4-8 (category-ratio scale)
Component Strength and Muscle Endurance Training
Activity Resistance training: low resistance with high repetition
Mode Variable resistance or hydraulic weight machines
  Isotonic weight machines
  Free weights
Frequency 2-3 days/wk
Duration One set of 3-20 repetitions on 8-10 exercises that include all of the major muscle groups
Intensity Volitional exhaustion on each set, or
  Stop two to three reps before volitional exhaustion
Component Flexibility
Activity Static stretching of all major muscle groups
Frequency Minimum of 2-3 days/wk
  Ideally 5-7 days/wk
Duration 15-30 s/exercise, 2-4 stretching exercise sets
Intensity Stretch to tightness at the end of the range of motion but not to pain

RPE, Rate of perceived exertion.

Warburton et al., 2006.76

Modified from Whaley MH, Brubaker PH, Otto RM, editors: ACSM’s guidelines for exercise testing and prescription, ed 7, Philadelphia, 2006, Lippincott Williams & Wilkins.

It is imperative that the personnel supervising the exercise program be appropriately trained in the implementation of exercise prescriptions in people with chronic illnesses and special needs. The American College of Sports Medicine offers certification programs to those with appropriate backgrounds such as exercise science or kinesiology, nursing, occupational therapy, physical therapy, and respiratory therapy. In the initial exercise sessions, the individuals supervising the exercise program should monitor patients closely and adjust the intensity or duration of the session according to the appearance of exertional symptoms. After the patient is established at an appropriate intensity and duration, the progression of the patient must be monitored and evaluated to adjust the prescription for optimal effectiveness. The goal of the program should be a safe, effective, and enjoyable exercise regimen. Although beneficial results have been observed with exercise programs of 8 to 12 weeks in healthy individuals, those with pulmonary diseases might require longer periods of participation to show substantial results.

Exercise in Chronic Obstructive Pulmonary Disease

All studies of exercise in COPD take into account the severity of the respiratory disability (Table 34-3).40 Numerous studies have been carried out on the effects of exercise on patients with COPD over the past quarter century (Box 34-3). In patients with COPD, cardiorespiratory endurance exercise therapy has been shown to improve maximum or symptom-limited aerobic capacity, timed walk distance, and health-related quality of life. Adding resistance training to the rehabilitative regimen can provide additional benefits such as increased fat-free mass and muscle strength.

Table 34-3 Classification Scheme for Chronic Obstructive Pulmonary Disease Severity: National Heart, Lung, and Blood Institute–World Health Organization Global Initiative for Chronic Obstructive Lung Disease Criteria

Stage Criterion
0 Normal lung function
1 (Mild) FEV1 ≥80% of predicted
2 (Moderate) 50%-79% of predicted
3 (Severe) 30%-49% of predicted
4 (Very severe) FEV1 <30% of predicted or presence of respiratory failure or clinical signs of right-sided heart failure

In the presence of FEV1/FVC ratio less than 70%.

Several adjunct modalities might reduce the extreme breathlessness and peripheral muscle fatigue that prevent patients with severe COPD from exercising at higher intensities.1 Continuous positive airway pressure and NIPPV during exercise might reduce the perception of dyspnea. Taking part of the work of breathing away from the respiratory muscles and reducing intrinsic positive end-expiratory pressure are considered two mechanisms by which these techniques relieve dyspnea. Nocturnal NIPPV in selected patients can improve their ability to exercise during the day. Adding electrical stimulation to strength exercises for peripheral muscles has been shown to further improve muscle strength in patients with COPD. Interval training with rest periods is capable of producing training effects in those who cannot tolerate a sustained period of exercise. Oxygen supplementation, even in patients who do not desaturate during exercise, allows for higher exercise intensities and produces a superior training effect. High-intensity physical group training in water can produce significant benefits as well.75

After an initial exercise rehabilitation program, patients must continue to participate in routine exercise to prevent the positive effects of exercise from being lost. Continuous outpatient exercise training, home-based or community-based exercise programs, or exercise training in groups of persons with COPD is necessary to sustain the benefits acquired during the initial rehabilitation program.67

Exercise in Asthma

Asthma severity guidelines published in 1997 and updated in 2002 by the National Heart, Lung, and Blood Institute are based on clinical symptoms during the day and at night, and on the results of pulmonary function testing.17 The two major categories of asthma patients are those who have it intermittently and those with persistent asthma. Bronchial biopsies in patients with intermittent asthma show evidence of ongoing airway inflammation. Studies have shown that aerobic exercise improves overall fitness and health of asthmatic patients.

A mouse model of asthma has been developed in which the effects of exercise have been studied.53

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