HOUSTON--More than half of the patients who present to M.D. Anderson Cancer Center’s emergency room have a complaint of dyspnea, Sandra Henke, RN, a thoracic oncology nurse at M.D. Anderson, said at the Center’s 2nd Annual Nursing Conference. "Even when there are other emergency symptoms, breathing difficulties are the most pronounced because they cause the most distress for the patient," Ms. Henke said.

Dyspnea can also be problematic for the medical staff because it is difficult to determine its direct cause. "The mechanisms that cause dyspnea are complex, which may prevent us from immediately determining its underlying cause," she said.

The cancer patients most likely to present with dyspnea are those with lung cancer, though often not until the later stages of the disease.

"There is a prevailing but false assumption that patients with lung cancer instantly suffer from shortness of breath, hemoptysis, and coughing," Ms. Henke said. "In fact, patients rarely complain of breathing problems in the early stages of lung cancer, because at this point, the lesions are peripheral and not near a major airway, so there is no blockage that would cause breathlessness."

Dyspnea is more often a symptom of later-stage lung cancer. Studies have shown that when patients with lung cancer begin to complain of dyspnea that is severe enough to require medical evaluation, they usually have a life expectancy of only 2 to 3 weeks. "These are cases in which there is clearly an obstruction to the airway," Ms. Henke said.

The second tumor group in which dyspnea most commonly occurs is breast cancer. In this group, breathing problems are caused by pleural effusions rather than by a blockage in the lungs.

Possible Causes

"When determining the cause of dyspnea in the cancer setting, it is important to consider which cancer treatments the patient has undergone," Ms. Henke stressed. Chemotherapy drugs can cause pulmonary toxicity and produce dyspnea. Bleomycin (Blenoxane) may be particularly harmful because it can infiltrate interstitial tissues and lead to pulmonary fibrosis.

Biologic response modifiers (such as interleukin-2) can cause a shift in the pulmonary fluids, which can lead to dyspnea.

Radiation delivered to the chest can cause pulmonary compromise, which is most problematic for patients with lung cancer. Surgical dissection for lung cancer places patients at substantial risk for dyspnea, particularly when it is performed on patients with other risk factors.

"Patients with a long-term smoking history, for example, will likely present with preexisting pulmonary compromise," Ms. Henke said. "When a smoker undergoes lung resection, the risk of dyspnea is increased."

Another common cause of dyspnea is pulmonary embolism, she said. This condition can be the result of surgery or long-term immobility and is characterized by a slow, gradual collection of fluid. These patients report feeling like they are choking or smothering.

Patients with adenocarcinoma of the lung very often present with thrombosis, which can result from pulmonary embolism. Because it is difficult to detect, pulmonary embolism is commonly missed on diagnosis. "Clinical findings are inclusive for pulmonary embolism," Ms. Henke said. "You really need a ventilation scan for a more accurate diagnosis."

Stepwise Assessment

The first steps in assessing the cause of dyspnea are the physical examination and medical history. "In the cancer setting, it is particularly important to document the tumor history and cancer treatment background," Ms. Henke said.

The next step is the pulmonary assessment. "Make a visual inspection to see if the chest is rising and falling symmetrically," she suggested. "If it is not, there may be a blockage in a major airway."

Also, because the heart and lungs work so closely together, a complete pulmonary and cardiac evaluation is recommended. In many cases, these evaluations may point to a problem other than dyspnea. "If jugular vein distention is detected, the problem may be congestive heart failure rather than dyspnea," Ms. Henke said.

The third step is evaluation of the patient’s breathing sounds. Some breathing disorders are noticeable without a stethoscope because they are characterized by marked distress or unnatural breathing patterns.

"The patient may be struggling to catch his or her breath, or normal breaths may be replaced by a wheezing or crackling sound," Ms. Henke said. "These are clear signs of an obstruction in the trachea, main bronchus, or another airway."

The final and key step in determining the cause of dyspnea is the chest x-ray. "Ninety percent of cases of dyspnea are confirmed on chest x-ray," she said. "The x-ray helps us determine whether we are dealing with some other ailment that could cause breathlessness."

Treating Dyspnea

Dyspnea is typically treated with medications, such as albuterol, administered through a bronchial dilator. "Albuterol can cause agitation and irritability, however, so patients who receive this prescription should be monitored closely," Ms. Henke warned.

Steroids are the easiest to use and most effective drugs for relieving dyspnea, and have been used extensively in terminal patients and patients who have undergone radiotherapy, but there are long-term complications associated with this family of drugs. Other drugs that may be used include cough medicines, certain pain medications, diazepam, hydromor-phone, morphine, and oxygen.

It is important to remember that dyspnea is a complex symptom and that in assessing this problem, the care team must take into consideration more than the physical symptoms, Ms. Henke said. "Just because a person reports shortness of breath, it is not an immediate sign that their oxygen level is low. A chest x-ray is vital, and other scans may be needed," she said.

Also, the care team must remember that dyspnea may have a psychological component. Breathlessness can induce anxiety, and the more anxious patients become, the more breathless they will become, she said, "so a manageable situation can easily and quickly evolve into an emergency."