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10: Cough, Fever, and Respiratory Infections

CHIEF COMPLAINT

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Ms. L is a 22-year-old woman who comes to your office in August complaining of cough and fever. She reports that she was in her usual state of health until 3 days ago when a cough developed. Two days ago, a low-grade fever (37.8°C) developed, which increased to 38.8°C yesterday. She reports that her sputum is yellow and that she has no chest pain or shortness of breath.

CONSTRUCTING A DIFFERENTIAL DIAGNOSIS

The causes of cough and congestion vary from trivial self-limited upper respiratory viral infections to serious, imminently life-threatening forms of pneumonia. The approach to such patients focuses on 2 pivotal questions. First, does the patient have symptoms, signs, or risk factors for pneumonia that warrant a chest radiograph or other evaluation? Second, in patients with pneumonia, is it simply a community-acquired pneumonia (CAP) or another type of pneumonia that requires alternative/additional treatment (such as Pneumocystis jirovecii pneumonia [PCP] or tuberculosis [TB])?

A variety of symptoms suggest pneumonia because they are unusual in upper respiratory tract infections or bronchitis. These include dyspnea, high fever (with the exception of influenza [see below]), altered mental status, hypoxia, hypotension, dullness to percussion, crackles, decreased breath sounds, bronchophony, or egophony. Any patient with such symptoms or signs requires a minimum evaluation with a chest radiograph to rule out pneumonia. A chest radiograph should also be strongly considered in patients at increased risk for poor outcomes, including immunocompromised patients; elderly patients; and those with heart failure (HF), chronic kidney disease, or chronic obstructive pulmonary disease (COPD) (in whom abnormal lung findings are also more difficult to appreciate). Figure 10-1 shows a diagnostic algorithm illustrating the initial approach to patients with cough and congestion.

Figure 10-1.

Initial approach to the patient with cough and congestion.

1This chapter will focus on patients without known immunocompromise. For patients known to be HIV+ see Chapter 5. See Chapter 33 for patients with underlying COPD. Readers are referred elsewhere for transplant recipients, granulocytopenia, or other immunosuppressive conditions.

2Febrile patients very likely to have influenza may not require a chest radiograph. That would include patients fulfilling all of the following criteria: influenza season, unvaccinated patient, maximum fever within the first 24 hours and without dyspnea or focal lung findings. Clinical judgment is required.

3A normal chest film does not completely rule out pneumonia. Patients in whom there is a high clinical suspicion (eg, those with focal crackles and fever) should be empirically treated for pneumonia with consideration for additional radiographic imaging (eg, follow-up chest film or CT scan. See Community-acquired pneumonia, Evidence-Based Diagnosis section.)

COPD, chronic obstructive pulmonary disease; DM, diabetes mellitus; PA, posterior-anterior

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In patients with pneumonia, the next pivotal step is to determine the likely etiologic pathogen(s), which will ensure patients receive appropriate therapy. Even in ...

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