The following questions can help distinguish cardiovascular (CV) from pulmonary or other causes of dyspnea:
- 1. Are there associated non-pulmonary symptoms such as palpitations, pre-syncope, and/or chest pain?
The presence of cardiac-associated symptoms should prompt evaluation for processes including exercise-induced pulmonary arterial hypertension, cardiomyopathies, and valvular abnormalities.
- 2. Does dyspnea occur suddenly and unexpectedly, or does it occur regularly and predictably with exercise?
Intrinsic pulmonary causes of excessive dyspnea with exercise should occur with nearly every episode of exertion. An exception to this statement might be a particular environmental trigger (e.g., cold air) that occurs intermittently with exercise. Truly paroxysmal episodes of excessive dyspnea should raise suspicion for nonpulmonary diseases manifesting as paroxysmal dyspnea, including cardiac arrhythmias or hyperventilation syndrome.
- 3. When does dyspnea occur during exercise?
The onset of dyspnea at peak exercise may suggest a CV-related arrhythmia or exercise-induced vocal cord dysfunction (VCD) or laryngeal spasm; symptoms often regress as exercise intensity is reduced. In contrast, exercise-induced bronchoconstriction (EIB) is reliably most intense at 10 to 15 min of maximal exercise and tends to resolve gradually over 1 h of sustained exercise. Repeat exercise bouts within 4 h of initial symptoms tend to reduce dyspnea in EIB.
- 4. Is there audible wheezing or stridor during the dyspnea episode, and does it occur with inspiration, expiration, or both?
Audible wheezing during expiration is a strong clinical clue for EIB. However, if noticed during inspiration (stridor), especially if there is no expiratory wheeze and the sounds are associated with hoarseness, VCD should be considered.
- 5. Are there environmental triggers of dyspnea beyond that of exercise?
Allergic individuals are more likely to have EIB and/or exercise-induced asthma. Typical asthmatic triggers such as pollens, cold air, molds, air pollution, animal dander, cigarette or wood smoke, and others can suggest bronchospasm as the underlying etiology.
- 6. Is there an associated cough, and is it productive?
The presence of a nonproductive cough during exercise may be a result of bronchoconstriction. However, cough occurring in the absence of exercise or when not exposed to an environmental trigger may suggest intrinsic airway disease. If coughing is productive and persistent, diagnoses such as bronchiectasis should be considered.
Inspect the chest for bony abnormalities such as kyphoscoliosis and pectus excavatum, both of which may lead to exercise limitation, and for symmetry of the posterior chest wall during a normal inspiration as deviation of the chest wall excursion may suggest advanced pleural filling process. Also, inspect the hands for clubbing and cyanosis for evidence of chronic cardiopulmonary conditions.
Auscultate for expiratory wheezing that suggests asthma. The episodic nature of asthma makes this examination finding poorly sensitive. Focal findings may indicate localized airway abnormalities such as bronchiectasis or obstruction of the airway lumen by a foreign body. Inspiratory squeaks should be differentiated from upper airway inspiratory stridor by listening over the trachea, as the former typifies bronchiolitis, while the latter, paradoxical VCD.
Case 1: An Amateur Male Cyclist
A 33-year-old cyclist presents with excessive dyspnea while exercising over the last 6 months. He notes that his symptoms have progressed since moving to a new location because of his job as an information technology consultant. He has no personal history of allergy. His symptoms are most pronounced shortly into his cycling routine but seem to plateau as he continues to ride, and his return rides are seemingly less symptomatic. Office spirometry is normal; however, exercise spirometry reveals 15% reduction in Forced Expiratory Volume (FEV1) during the first 10 min of cycling and the diagnosis of EIB is made.
Key Point: The presence of a refractory period wherein dyspnea is mitigated within 4 h of symptoms onset suggests EIB; most importantly, exercise spirometry that reveals a drop in FEV1 from a normal baseline confirms the diagnosis.
Case 2: Teenage Football Player
A 16-year-old adolescent male presents with worsening dyspnea during his football tryout routines at high school. The symptoms have been slowly progressive over the preceding years despite utilization of both an inhaled short-acting bronchodilator and inhaled corticosteroid. His symptoms are particularly pronounced at peak exercise and gradually resolve as he stands on the sidelines. His physical examination result is normal, but postexercise office spirometry exhibits and inspiratory flow “cutoff.” Referral to an otolaryngologist for direct laryngoscopy confirms the diagnosis of paradoxical vocal cord movement with inspiration.
Key Point: VCD can mimic EIB, and the diagnosis should be confirmed before using bronchodilators for extended periods. A referral to speech pathology is warranted.
Case 3: Adult Male Marathon Runner
A 43-year-old marathon runner is referred for excessive dyspnea while running. His symptoms have progressed for over 3 years; he notes following an admission for a severe pneumonia. While not exercising, he has complained of productive cough with yellow sputum but no fevers and no chills. He has attributed the cough to his severe postnasal drip that is exacerbated by seasonal allergies. Physical examination result is remarkable for right lower lobe rhonchi with localized inspiratory squeaks. A subsequent chest computerized tomography confirms an area of focal right lower lobe bronchiectasis, and he is referred to a pulmonologist for further evaluation.
Key Point: Associated productive cough with localized physical examination findings suggest focal airway disease.
Case 4: Young Female Physician Who Works Out
A 27-year-old medicine resident is referred for worsening dyspnea during her normal exercise routine along the beach. The dyspnea has worsened as the days have become short in the fall months; her inability to exercise generates a considerable amount of frustration. Her dyspnea begins almost immediately as she runs and does not abate although she notes no wheezing. She has no history of allergy. Her examination, spirometry, and exercise spirometry results are all normal. She is referred for cardiopulmonary exercise testing, and she is noted to have the onset of rapid shallow breathing in anticipation of the test, which continues throughout testing. Her minute ventilation on exercise testing is dramatically elevated. She is referred to a counselor for anxiety management.
Key Point: Anxiety can present with asthma-like symptoms.
1. Crapo RO, Casaburi R, Coates AL, et al. Guidelines for methacholine and exercise challenge testing-1999. This official statement of the American Thoracic Society was adopted by the ATS Board of Directors, July 1999. Am. J. Resp. Crit. Care. Med.
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