The American Thoracic Society (ATS) has issued a consensus statement on the mechanisms, assessment and management of dyspnea. Published in the January 1999 issue of the American Journal of Respiratory and Critical Care Medicine, the 19-page statement, developed by an 18-member expert committee, addresses mechanisms of dyspnea, assessment and treatment.
Decreases in functional status and quality of life, and disabilities are frequently consequences of dyspnea. The ATS believes that a better understanding of all aspects of dyspnea is necessary in order for physicians to appropriately treat patients with shortness of breath.
The ATS states that the underlying causes of dyspnea are chronic obstructive pulmonary disease (COPD), asthma, interstitial lung disease, neuromuscular disorders, lung cancer and coronary disease. The ATS defines dyspnea as a subjective experience of breathing discomfort consisting of qualitatively distinct sensations that vary in intensity. Physiologic, psychologic and environmental factors all may play a role. The severity varies widely among patients. Interventions discussed in the statement include exercise training, oxygen therapy, pharmacologic therapy, nutrition, positioning, continuous positive airway pressure, steroid therapy, cognitive-behavioral approaches and others.
The assessment of dyspnea is an important aspect of the evaluation and management of the disorder. Historically, the evaluation of dyspnea has emphasized the search for corresponding pathophysiology. Diagnostic testing should identify the specific nature of the disorder. Standard spirometry and lung volume measurements may be useful in assessment. Standard questionnaires are available to determine the association between levels of activity that are related to dyspnea. Tools are also available to relate the severity of symptoms with observed levels of cardiac and pulmonary responses during performance of tasks. The ATS notes that questionnaires relating dyspnea to quality of life are useful even though they are not yet a routine part of the history and physical examination.
After the physician determines the underlying cause of dyspnea, the focus should be on the symptoms of breathlessness, including trying to determine quality, intensity, duration, frequency, and the amount of distress or discomfort. The statement recommends that physicians distinguish between two broad categories: conditions associated with cardiovascular dyspnea involving inadequate oxygen delivery to the tissues; and pulmonary dyspnea. Sometimes the problem involves a combination of symptoms associated with the two major disorders. Comorbid conditions as well as psychologic status need to be considered in the evaluation of the significance of symptoms, according to the ATS.
The statement points out that the physiologic bases for the treatment of dyspnea lie in the discussion of the mechanisms underlying shortness of breath. The ATS categorizes treatments for dyspnea as related to pathophysiologic mechanisms rather than specific diseases. These categories of mechnisms are listed in the table. The ATS acknowledges that questions remain, and research is needed in this area but believes that an approach to treatment that links mechanisms and treatments will help minimize the impact of dyspnea on the patient.
Information on some of the treatments reviewed in the statement follows:
REDUCE VENTILATORY DEMAND
Exercise Training. Exertional dyspnea decreases and exercise tolerance improves in response to exercise training in patients with COPD, even in patients with advanced disease. Studies have established that for patients with COPD who remain breathless despite optimal pharmacologic therapy, exercise training can provide significant symptomatic benefits.
Pharmacologic Therapy. Two types of medications have been evaluated as a means of alleviating dyspnea: opiates and anxiolytics. Numerous studies have shown that opiates relieve dyspnea and improve exercise performance in patients with COPD, although evidence is insufficient to recommend their regular use in long-term management. Anxiolytics have the potential to relieve dyspnea by depressing hypoxis or hyercapnic ventilatory responses.
Fans. The movement of cool air with a fan has been noted to reduce dyspnea in pulmonary patients.
Altered Breathing Patterns. Breathing retraining including diaphragmatic breathing and pursed lip breathing has been advocated to relieve dyspnea in COPD patients. The effectiveness of this method is highly variable.
REDUCE VENTILATORY IMPEDANCE
Continuous Positive Airway Pressure. Continuous positive airway pressure has been demonstrated in some studies to relieve dyspnea during asthma attacks, when patients are being weaned from ventilators and during exercise sessions for patients with advanced COPD.
IMPROVE INSPIRATORY MUSCLE FUNCTION
Nutrition. Some research has shown that respiratory muscle function can be improved in response to nutritional repletion with short-term use of enteral or parenteral nutrition and in outpatient and inpatient controlled trials of oral supplementation. Others have shown the benefits of outpatient programs that provide patient education and distribute nutritional supplements.
Positioning. Body positions that increase abdominal pressure may improve overall inspiratory muscle strength and the function of the respiratory muscles.
Steroids. Use of steroids in pulmonary patients helps reduce inflammation and increases vital lung capacity in interstitial lung disease. The use of steroids for the purpose of reducing dyspnea must be weighed against the adverse effects of steroids on muscles.
ALTERED CENTRAL PERCEPTION
Cognitive-Behavioral Approaches. In patients with pain syndromes, distraction, relaxation and education about the symptom have been shown to modify the intensity of the symptom, increase tolerance and decrease distress. Relaxation training may improve symptoms in the short term. Monitoring symptoms helps patients and physicians understand the patterns of symptom intensity.
Other treatments reviewed in the statement include oxygen therapy, supplemental oxygen during exercise, vibration, ventilator settings, surgical volume reduction, desensitization, inspiratory muscle training and education.