Respiratory muscle weakness should be considered in patients whose dyspnea cannot be explained by pulmonary disease, cardiac disease, anemia, or deconditioning. First symptoms may occur when respiratory muscles are under increased load, such as when standing in deep water, swimming, or in the supine position. A commonly prescribed drug is ipatropium bromide (Atrovent®). Bronchodilators - These drugs work by opening (or dilating) the lung passages, and offering relief of symptoms, including shortness of breath. These drugs, typically given by inhalation (aerosol), but are also available in pill form.