Shortness of breath, air hunger, breathlessness, or the medical term dyspnea—all terms trying to capture one of the most unsettling feelings that a person can have. That feeling that you are under water and need a snorkel. The sensation of tightness in the chest and anxiety all wrapped up together. That feeling of being “too aware” of your own breathing. Dyspnea is the medical term for this symptom, and for simplicity’s sake, I will use that word to encompass all the different terms. For patients with cancer, this symptom occurs commonly but is difficult to treat and has gotten far too little attention than cancer-related pain. It has been estimated to occur in 80% of patients who have an advanced cancer and in up to 20% of all cancer patients regardless of the stage of their disease.
What causes shortness of breath?
Ultimately, this sensation is a complicated one and still not completely understood. Dyspnea happens because of a mismatch of breathing effort with the body’s signals for breath. There are several different types of signals that are at play in dyspnea—chemical, such as levels of carbon dioxide and oxygen in the blood; mechanical, such as the stretch of chest muscles; and neural or vagal, related to the nervous system of the lungs. On a more operational level, there are three major mechanisms for dyspnea that create a mismatch: 1) an increased workload requiring more effort; 2) an increase in the amount of lung muscle needed to achieve a normal workload; and 3) an increase in the need to ventilate unrelated to the lungs. While it is not entirely understood, anxiety and depression both are associated with higher frequency of dyspnea as well, presumably through mechanisms in the brain related to mood.
In patients with lung cancer, there are multiple reasons dyspnea occurs:
Treatment should start with a thorough evaluation for the underlying cause; this could mean imaging (chest X-ray, CT scan, etc) and laboratory tests (blood counts, chemistries, etc) in addition to a doctor’s visit. The primary approach should be as follows:
This could mean blood transfusion in the case of symptomatic anemia or drainage of pleural fluid, for example. Then, if that is not working, there are some additional approaches to take.
Pulmonary rehabilitation and exercise have therapeutic benefit by decreasing dyspnea for patients with lung cancer but most of the studies have demonstrated this effect in patients who are functioning well and have disease that can be controlled with surgery. This does make some intuitive sense in that you are training the respiratory muscles to do more work through aerobic exercise.
There has been some evidence to suggest that oxygen therapy can help treat dyspnea in patients with cancer. However, the effectiveness of oxygen for dyspnea is proportional to how low the blood oxygen levels are and tend to be most helpful when the oxygen levels are very low. In general, to qualify for coverage of home oxygen, a patient’s oxygen levels have to go below a certain number. There was a recent study out of Duke that compared oxygen therapy versus regular air for patients who had dyspnea but whose oxygen levels were not low enough to qualify for oxygen. This study found no difference in the effect of oxygen versus air, but interestingly, patients had the same improvement in their dyspnea whether they had oxygen or air.
Opioids: Opioids have long been used in the treatment of dyspnea. Why do they work? Chemical opioid receptors, when triggered, dampen the feeling of dyspnea. There is a fear that opioids will cause someone to stop breathing. However, given in moderate doses for dyspnea, they have proven to be efficacious and safe to the point that the American College of Chest Physicians came out with a consensus statement in 2010 on dyspnea in patients with advanced lung or heart disease, recommending that physicians “titrate opioids…for the relief of dyspnea.” Sometimes, treating the underlying cause does not resolve the dyspnea, so usage of opioids can be certainly used alongside other treatments targeting the cause.
Anti-anxiety medications such as the benzodiazepines (Ativan (lorazepam) or Xanax (alprazolam)), as well as selective serotonin reuptake inhibitors (SSRIs) like Paxil (paroxetine) have been used in the treatment of dyspnea. This is based on the fact that patients who have anxiety report more dyspnea than other patients. In light of the “brain component” modulating the sensation of dyspnea, it makes sense that treating the anxiety would reduce the amount of dyspnea experienced, though this has not played out consistently in studies.
Integrative medicine therapies
Heliox: This is a mixture of oxygen and helium and has demonstrated some modest benefit in patients with lung cancer to decrease dyspnea. It’s expensive and relatively limited in its availability, so it has not been used very much yet. More trials are definitely needed to see if this is worth pursuing further.
Acupuncture has been shown in a few small trials to improve dyspnea in patients with lung cancer as well as patients with emphysema, but not much further than that. Recent reviews have not demonstrated evidence to recommend it routinely.
I hope this summary provides a helpful summary of this common and challenging symptom, along with some useful treatment ideas. Your questions and comments are always very welcome.