Nutrition, Airway Clearance, and Immunizations
Other important facets of COPD management include nutritional support, assistance with secretion clearance (see Section 21.3.3), and vaccinations. Malnutrition is common as COPD progresses, and contributes to respiratory muscle weakness and diminished immune system reserve. Cachexia itself, dehned as BMI < 17 in men and <14 in women, has been found to be an independent predictor of mortality in patients with COPD.56 Engaging nutritional support services has been shown to be effective in improving exercise performance in malnourished COPD patients.57 Since respiratory infection is the primary cause of acute exacerbation, vaccinations against typical etiologic agents (such as influenza and pneumococcus) are encouraged (Figure 21.6).
Rehabilitation of the Older Patient with COPD
Patients with COPD experience exaggerated age-related declines in lung function and corresponding heightened increases in exertional dyspnea and exercise intolerance. These symptoms are attributable to the changes in pulmonary function described earlier: namely, decreased airway diameter, enhanced by the loss of the tethering support structures due to progression of emphysema, along with increased mucoid secretions in the airways themselves; decreased efficiency of the respiratory muscular apparatus related not only to normal age-related changes but also to excessive flattening of the diaphragm; decreased gas exchange capabilities due to destruction of alveoli and thickening of the alveolar-capillary membranes (scarring); and increased dynamic hyperinflation.
These changes disrupt the balance between respiratory load and the respiratory pump, resulting in exertional dyspnea and respiratory insufhciency. The struggle to breathe with exertion initiates a downward spiral of inactivity leading to cardiovascular deconditioning, accelerated muscle depletion, progression of dyspnea, further inactivity and, ultimately, disability. It should be mentioned that physical inactivity is not unique to advanced COPD; it is already pronounced in patients with mild
FIGURE 21.6 COPD: Key points.
FIGURE 21.7 Spiral of disability in COPD.
or moderate COPD,58 even preceding the onset of dyspnea.59 In addition, research into the nature of COPD-related disability reveals that the “nonrespiratory” realm of reduced muscle strength and lower extremity dysfunction are at least as critical as lung function impairment in causing exercise intolerance and disability.60 Indeed, the quadriceps cross-sectional area has been found to be a predictor of mortality in patients with COPD independent of lung function.61 Rehabilitation must therefore take into account not only respiratory limitations in patients with COPD, but also coexisting nonrespiratory impairments (Figure 21.7).