Exercise for COPD: take it without a grain of salt.

Hyperosmolar saline has been used for many years for sputum induction as an aid to diagnosing lower respiratory infections, especially tuberculosis.1 More recently 7% saline has been used as a therapeutic aerosol to assist airways clearance in persons with cystic fibrosis (CF) and non-CF bronchiectasis. Studies have shown that the regular, twice daily inhalation of 7% saline aerosol is safe for persons with CF and helps promote mucus clearance, with improvement in pulmonary function and a decrease in respiratory tract exacerbations.2,3 Long-term studies in CF have established the role of hyperosmolar saline as a therapeutic agent, and it is now recommended as part of the treatment regimen for this disease. As a result of these encouraging findings, there has been a rush to consider using hyperosmolar saline for variety of other pulmonary diseases, including chronic obstructive pulmonary disease (COPD) and asthma. In contrast to CF, there are few data that show benefit of hyperosmolar saline therapy in these conditions, but compelling data showing an adverse response to the inhalation of 3% saline in persons with moderate to severe COPD.4 Despite this, the relatively low cost of hyperosmolar saline and its safety profile when used to treat CF have led to its use for the treatment of COPD. In contrast to the paucity of data related to the effectiveness of hyperosmolar saline, it is clear that structured exercise rehabilitation programs are of great benefit to patients with COPD. A Cochrane review concluded that exercise rehabilitation “relieves dyspnea and fatigue, improves emotional function, and enhances patients’ sense of control over their condition. These improvements are moderately large and clinically important. Rehabilitation forms an important component of the management of COPD”.5 Exercise improves functional exercise capacity, as measured by shuttle walking or the standardized 6-min walk distance, it improves strength and nutritional status, and it promotes airway clearance. Although exercise programs are less expensive than even the cheapest of drugs, for exercise to be beneficial it requires a greater time and effort commitment on the part of patients. In this issue of RESPIRATORY CARE, Valderramas and colleagues present results of a study where they asked the question, “If we enroll subjects with COPD in an exercise rehabilitation program, will they obtain additional benefit if they also inhale hypertonic saline?” The answer to this question was a resounding “No”.6 Although all subjects were enrolled in exercise rehabilitation and had significant improvement in 6-min-walk test distance and a decrease in dyspnea, the improvement, particularly in functional exercise capacity, was greater in those who inhaled iso-osmolar saline, as compared to 3% hyperosmolar saline.