Differential Diagnosis: Pulmonary

1. Airway Obstruction

• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Mechanical obstruction (foreign body, tumore)
• Obstructive sleep apnea

2. Infection

• Upper respiratory infection
• Sinusitis
• Lower respiratory (bronchitis, pneumonia)
• Viral
• Atypical organisms
• Myobacteria
• Fungal
• Other Opportunistic

3. Cardiac

• Ischemia
• Congestive heart failure
• Valvular heart disease
• Congential heart abnormalities (i.e., atrial septal defect)

4. Thromboembolic

• Pulmonary embolism
• Septic emboli

5. Tumors

• Malignant
• Primary lung cancer
• Metastatic to the lung
• Benign
• Carcinoid
• Hamartoma
• Other

6. Injury or Toxin-related

• Tobacco
• Inhalation injury (i.e., fire smoke)
• Injection drug use (ritalin, others)
• Asbestosis
• Silicosis
• Other

7. Interstital Lung Disease

• Infections
• Radiation exposure
• Aspiration
• Medications
• Lymphangitic spread of malignancy
• Immunologic/ Inflammatory arthridities (i.e., Goodpasture's syndrome, Rheumatoid arthritis, lupus, sarcoidosis)
• Systemic disorders (i.e., scleroderma, collagen vascular disorders)

8. Abnormal Breathing Patterns

• Obstructed breathing: In the presence of airway obstruction, the work of breathing is minimized by maintaining a slow rate and increased tidal volume. Either inspiration or expiration may be prolonged and labored and is often associated with audible wheezing or stridor.
• Kussmaul's breathing: Regular pattern, moderate or slightly rapid rate, an abnormally large tidal volume and usually little apparent effort. This is the pattern seen at rest in patients with metabolic acidosis, and is the pattern adopted automatically by individuals during exercise.
• Restricted breathing: Small tidal volume and a rapid rate; seen in patients with decreased distensibility of the lung or chest wall or with reduction of vital capacity from other causes.
• Gasping respirations: This pattern consists of irregular quick inspirations associated with extension of the neck, followed by a long expiratory pause. It is characteristic of severe cerebral hypoxia, and is also seen in cardiovascular shock or other conditions with severely reduced cardiac output.
• Cheyne-Stokes respiration: Periodic breathing pattern characterized by alternating periods of hypoventilation and hyperventilation. Typically an apneic phase will last for 15-60 seconds followed by a phase of increasing tidal volume with each breath and then decreasing progressively to the apneic phase. This pattern is seen at times in normal infants and healthy elderly individuals, and normal persons at high altitude. Disease states associated with cheyne-stokes respiration include increased intracranial pressure, uremia, coma, and after administration of a respiratory depressant such as morphine.
• Sighing respirations: Markedly irregular pattern of frequent, deep, sighing inspirations, seen during severe anxiety.

(Source: Fishman)

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