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Michael W. Rabow, MD
Director, Symptom Management Service
Helen Diller Family Comprehensive Cancer Center
Associate Professor of Clinical Medicine
Department of Medicine
University of California, San Francisco
Dyspnea is a subjective sensation of difficulty breathing. It is described by many as shortness of breath, breathlessness, or not being able to get enough air. The sensation can originate from both chemical and mechanical receptors in the lungs, chest wall, muscles, brain, and face. It can be a tremendously distressing sensation and is often accompanied by a sense of anxiety. Dyspnea and dyspnea on exertion can severely impair a person's physical abilities to pursue activities of daily living and can threaten a person's quality of life. Suffocation is one of the most dreaded fears people have about the end of life.
About one-quarter of patients with advanced cancer experience dyspnea. Dyspnea is very common with pulmonary diseases that impact the lungs' ability to exchange oxygen (for example, Chronic Obstructive Pulmonary Disease, Lung Cancer, and lung metastases). In addition, dyspnea can result from fluid filling the air spaces in the lungs (as with pulmonary edema from Congestive Heart Failure or fluid overload). Similarly, infection in the air space (pneumonia) creates dyspnea. Limitation in the lungs' ability to move air (as with Asthma) or restriction in its ability to expand (as with pneumothorax or scarring from radiotherapy) also can create dyspnea. Fluid around the lung can compress it (pleural effusions can result from infection or from various cancers). Even fluid or tumor growth in the abdomen (for example, from Ovarian Cancer) can compress the pulmonary space and create dyspnea. Severe anemia (low blood count) can decrease the body's ability to carry oxygen and lead to dyspnea. Blockage of blood vessels to the lungs (from a pulmonary embolus) is not uncommon as a complication from cancer. Severe obesity, urinary retention or even constipation can interfere with the ability to expand one's lungs adequately. Deconditioning and muscle weakness or fatigue may create dyspnea due to impacts on both the lungs and the heart and are likely under-appreciated in the assessment of shortness of breath and poor exercise tolerance. Finally, anxiety and pain both can create a sensation of breathlessness.
As dyspnea is a subjective sensation, it must be identified by the person him or herself and there is no test that can definitely identify dyspnea. However, dyspnea can be evaluated through a number of means. First, asking the person who is dyspneic to rate their level of shortness of breath on a 0-10 scale can be helpful in identifying and following the symptom over time. Second, a simple fingertip monitor (pulse oximetry) can show the level of oxygen in the blood and identify people who are hypoxic (low oxygen saturation). However, it is possible to be dyspneic with normal oxygen saturation and it is possible to feel well even when hypoxic. Other simple tests helpful in the work up of dyspnea are a chest xray or CT scan, a blood count, pulmonary function testing, and an arterial blood gas analysis (to examine the level of oxygen in the blood). For patients who cannot communicate, rapid breathing (tachypnea) generally is seen as a sign of respiratory distress.
When the underlying cause of dysnpea can be corrected without undue burden, this is the first line of treatment. Medications often used include diuretics, bronchodialators, antitussives, anticholinergics, and corticosteroids. Draining even a small amount of a large pleural or peritoneal effusion can have an immediate benefit. Frequently however, these effusions re-accumulate. Avoiding excess fluids can be key when the heart is unable to function adequately (even with maximal medical treatment) to prevent pulmonary edema.
Regardless of the ability to treat the underlying cause, the symptom of dyspnea can be alleviated through a variety of pharmacologic and non-pharmacologic means. These treatments can often best be administered by a multidisciplinary team, including a physician, nurse, social worker, psychosocial counselor, and nutritionist.
- -Supplemental oxygen is helpful for many people who are hypoxic. It has not been shown to improve dyspnea for people with normal oxygen saturations. However, it is reasonable to pursue a therapeutic trial of supplemental oxygen for any patient who is dyspneic to see if it helps improve symptoms. Some caution with supplemental oxygen must be observed for patients with COPD. Supplemental oxygen is typically delivered via nasal cannula. Oxygen masks are uncomfortable for many.
-Because of sensors in the face, air from a fan or window blowing on the face can be helpful. In addition, being close to a window and not feeling claustrophobic are appreciated by most.
-Positioning can be helpful. Most dyspneic people are more comfortable sitting up, rather than lying flat in bed.
-Opioids (such as morphine, codeine, or Roxanol) are the medications of choice for treating dyspnea. Opioids help suppress the sensation of shortness of breath, and typically at half the dose used for pain treatment. Oral morphine is typically used, although parenteral dosing is appropriate for urgent and severe symptoms, and subcutaneous dosing is possible as well. Nebulized morphine does not appear effective.
-Benzodiazepines can be used to manage the anxiety associated with (or causing) shortness of breath, especially acutely.
-Support groups, therapy, relaxation techniques, education, and even simple reassurance can help people with the anxiety and fear that often accompanies dyspnea.
-Physical conditioning, exercise training, and pulmonary rehabilitation programs are designed to improve a person's ability to breathe (including muscle strengthening) and often include group support to help manage anxiety.
-Adequate nutrition is necessary to allow physical rehabilitation and muscle strengthening.
-Acupuncture has not been proven to be beneficial.
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