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Diagnostic value of the physical examination in patients with dyspnea

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Consider pneumonia signs in combination

These physical examination maneuvers are time-honored and part of the rite of training for medical students and residents. As we have shown, they are not extremely helpful as individual tests in diagnosing pneumonia; however, they may be useful when used in combination as a clinical prediction rule or diagnostic algorithm. These rules often have higher diagnostic accuracy but drawbacks of taking more time and not being easily reproducible.

Signs of pneumonia
None of these physical findings has a very low (clinically significant) negative likelihood ratio; therefore, their absence is not useful in ruling out pneumonia. The positive and negative likelihood ratios for these physical signs are summarized in Table 3.6,9–14

PLEURAL EFFUSION

Pleural effusion commonly occurs in patients with congestive heart failure, pneumonia, and malignancies. The following are signs of effusion.

Dullness to percussion had a positive likelihood ratio of 5.7 from pooled data from 3 studies analyzed by Wong et al.13

Asymmetric chest expansion, in a study by Kalantri et al,14 had a positive likelihood ratio of 8.1 and a negative likelihood ratio of 0.29, the latter making it a reasonably good test to help rule out a pleural effusion.

Negative signs. Since a pleural effusion is an abnormal fluid collection in the pleural space and not the lung parenchyma, one would not expect it to cause loud breath sounds, adventitious sounds, or vocal resonance. Since these 3 findings emanate from the lung, their absence would be expected to support the presence of a pleural effusion.

Tactile fremitus, also known as vocal fremitus, is the vibration felt on the chest wall while the patient is speaking. Traditionally, the patient says “ninety-nine” as the examiner feels for asymmetry in vibration. A consolidation such as pneumonia increases the vibration, while fluid in a pleural effusion diminishes it.

Signs of pleural effusion
To summarize, diminished breath sounds, diminished tactile fremitus, and diminished vocal resonance (either egophony or bronchophony) should support a diagnosis of a pleural effusion. As expected, the evidence supports these tests, which have very good negative likelihood ratios (Table 4).14 Tactile fremitus, loud breath sounds, or vocal resonance, if present, make pleural effusion very unlikely.

DIAGNOSTIC ALGORITHM FOR PNEUMONIA OR PLEURAL EFFUSION

Patients presenting with cough or dyspnea will most likely be evaluated for pneumonia and pleural effusion, among other diagnoses. We propose the following physical examination strategy in this setting.

First, evaluate the patient for asymmetric chest expansion. The positive likelihood ratio for this sign is excellent for pneumonia (44.1) and moderate for pleural effusion (8.1); therefore, both conditions are possible with a positive test.

Second, percuss the chest. Dullness to percussion has a low positive likelihood ratio for pneumonia but a moderate one for pleural effusion.13 The absence of this sign is only modest in excluding a pleural effusion (negative likelihood ratio 0.31 in pooled data analyzed by Wong et al).13

Third, auscultate the chest to elicit normal, diminished, or adventitious breath sounds. Diminished breath sounds may be noted in both conditions, but vocal resonance (egophony or bronchophony) and tactile fremitus should not be present directly over a pleural effusion. Either vocal resonance or tactile fremitus in a patient with asymmetric chest expansion would strongly support the diagnosis of pneumonia.

Algorithmic approach to physical examination for suspected pneumonia vs pleural effusion.
Figure 2. Algorithmic approach to physical examination for suspected pneumonia vs pleural effusion.
In a parapneumonic effusion or pneumonia with a concomitant empyema, a combination of findings may be present. In this case the pneumonia will be superior to the effusion and the characteristic findings for each should be present over the areas of disease in the lung.

Figure 2 summarizes our proposed diagnostic algorithm for pneumonia and pleural effusion.

CHRONIC OBSTRUCTIVE PULMONARY DISEASE

COPD imposes a heavy burden on public health worldwide in terms of cost and mortality. It is the third leading cause of death in the United States, after heart disease and cancer.15

Spirometry remains the gold standard for diagnosis. The Global Initiative for Chronic Obstructive Lung Disease standard for diagnosing COPD was the better of 2 spirometry test results, showing a forced expiratory volume in 1 second (FEV1) and FEV1/forced vital capacity ratio less than 70%.16

Unfortunately, there is little evidence that physical signs aid in the early diagnosis of COPD, as physical signs of airflow limitation may not manifest until lung function is substantially impaired.17,18

Early inspiratory crackles had a positive likelihood ratio of 14.6 based on 2 small studies.19,20

Percussion dullness over the left sternal border in the fifth intercostal space should be present in the normal situation and is known as cardiac dullness. Absent cardiac dullness had a positive likelihood ratio of 16 and a negative likelihood ratio of 0.8 for diagnosing COPD in a study in 92 patients with a history of smoking or self-reported COPD.21 The kappa score was 0.49, signifying moderate interobserver agreement.

A combined strategy using the history and physical examination may have the highest diagnostic accuracy. Many of these combinations are too cumbersome for practical clinical use. However, 1 of them is based on only 3 questions21:

  • Has the patient smoked for more than 70-pack years?
  • Has the patient been previously diagnosed with chronic bronchitis or emphysema?
  • Are breath sounds diminished in intensity?

Answering yes to 2 of these questions gives a positive likelihood ratio of a diagnosis of COPD of 33.5.

Early detection of COPD may improve outcomes and lower healthcare costs and thus would be clinically useful. Unfortunately, a diagnostic approach using the history and physical in the early diagnosis of COPD remains uncertain at this time.

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