Dyspnea (Case 8)

Chapter 14
Dyspnea (Case 8)

Esaïe Carisma DO and Christina Migliore MD

Case: The patient is a 57-year-old forklift driver in a local warehouse. He has noticed progressive shortness of breath with exertion for the past 2 weeks. He is unable to climb one flight of stairs or walk one block on level ground without becoming short of breath. He denies any recent chest pain or lower extremity edema, but admits to a nonproductive cough. He is able to lie flat while sleeping, and he snores at night. He has a 20-year history of smoking one pack of cigarettes per day, but recently has reduced his smoking to fewer than five cigarettes daily. On physical exam, he is an obese man who does not appear short of breath or in any acute distress at rest. His respiratory rate is 18 breaths per minute, and there is no use of accessory muscles of respiration. He has a crowded oropharynx. His breath sounds are reduced bilaterally, but the chest is clear to auscultation. He has neither digital clubbing nor cyanosis. There is trace pitting edema observed at both ankles.

Differential Diagnosis

Emphysema or chronic obstructive pulmonary disease (COPD)	Pulmonary embolism	Pneumothorax
Asthma	Sleep apnea	Interstitial lung disease
Pulmonary edema	Pleural effusion	Interstitial lung disease

Speaking Intelligently

Dyspnea is a common symptom encountered in both the inpatient and outpatient settings. It is a subjective uncomfortable sensation of breathlessness, or running out of air, that varies in intensity. Similar to patients who present with pain, it is often difficult to quantify. In certain circumstances such as during exercise or at high altitudes, dyspnea is a normal sensation. However, it is abnormal when it occurs at rest or during usual levels of activity. Cardiac and pulmonary disorders are the most common causes of dyspnea, although noncardiopulmonary causes (e.g., anemia) must be considered.

PATIENT CARE

Clinical Thinking

• Determine the onset, duration, and severity of the symptom.

• Abrupt onset of dyspnea is usually of a cardiac or pulmonary origin that requires urgent diagnosis and treatment.

• Chronic dyspnea can generally be evaluated in an ambulatory setting.

History

A detailed history should focus on:

• The timing of the symptom

• Precipitating factors

• Associated symptoms

• Environmental irritant exposure (e.g., smoke from a building fire)

• Tobacco exposure history (active or passive smoking)

• Illicit substance abuse and use of specific medications

• Past medical, occupational, and travel history

Physical Examination

• General appearance: Severity of dyspnea may be evaluated by observing the patient’s respiratory effort, accessory muscles use, and mental status.

• Neck: Inspect for stridor, vein distension, and goiter.

• Chest and lungs: Include observation of respiratory excursion for symmetry. Observe configuration of the chest, and palpate for tenderness and subcutaneous emphysema. Absence of breath sounds may suggest pneumothorax or pleural effusion; these conditions are distinguished by percussion, in which hyper-resonance is demonstrated in patients with pneumothorax and dullness in patients with pleural effusion. Auscultation of the lungs may reveal wheezing, crackles, or rhonchi.

• Heart: Auscultation of the heart may reveal cardiac murmurs and/or extra heart sounds.

• Extremities: Examination of the digits is important to evaluate for clubbing and cyanosis. The lower extremities should be assessed for pitting edema, which may indicate volume overload or cor pulmonale (or both).

Tests for Consideration

• Pulse oximetry measures the patient’s level of oxygenation; however, normal values do not exclude anemia or certain hemoglobinopathies, which may limit oxygen delivery.	$3
• Complete blood count (CBC) may reveal anemia; severe dyspnea usually occurs at a hemoglobin level of 7 g/dL or below. Erythrocytosis may be seen in patients with severe COPD.	$11
• Electrocardiogram (ECG) may demonstrate myocardial ischemia or arrhythmia.	$27
• Peak flow meter assessment in a patient with suspected asthma may help determine the severity of the exacerbation.	$22
• Arterial blood gas (ABG) is useful in the hospital setting and selected outpatient situations. It assesses arterial pH and partial pressures of carbon dioxide and oxygen, and allows determination as to whether the condition is primarily respiratory or metabolic.	$27
• Brain natriuretic peptide (BNP) concentrations measured in the serum may help differentiate cardiac from noncardiac causes of dyspnea; patients with concentrations less than 100 pg/mL are unlikely to have acute heart failure.	$48
• Thyroid function testing may determine a systemic cause of dyspnea, such as hyperthyroidism or hypothyroidism.	$24
• D-dimer testing in serum is useful when pulmonary embolism is suspected. It has a high sensitivity but limited specificity. A negative test will essentially exclude pulmonary embolism as a cause of dyspnea.	$14
• Spirometry is essential in the evaluation of chronic dyspnea. It distinguishes patients with airway obstruction from those with restrictive lung disease and provides an objective measurement of lung impairment and an estimate of diffusing capacity.	$52

IMAGING CONSIDERATIONS

→ Plain chest radiographs (posteroanterior [PA] and lateral) may help to exclude conditions such as pneumonia, pulmonary edema, pneumothorax, emphysema, and pleural effusion.	$45
→ High-resolution computed tomography (CT) scan is recommended if interstitial lung disease is suspected and to further evaluate other abnormalities found on plain chest radiography.	$334
→ Echocardiogram is the initial test of choice if heart failure is suspected. Elevated right ventricular pressure may suggest pulmonary embolism or pulmonary hypertension.	$393
→ Venous Doppler of the lower extremities should be ordered to evaluate for deep vein thrombosis when pulmonary embolism is suspected.	$107