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A 66-year-old man with no known medical history was admitted after a fall while working at a silo on his farm. On physical examination, he had aphasia and right upper and lower extremity weakness. Computed tomography of the head revealed a large left intracerebral hemorrhage. He was intubated on hospital day 1 because of a depressed level of consciousness.

On hospital day 7, he developed fever with a temperature of 39.1°C (102.3°F), heart rate of 99 bpm, blood pressure of 146/53 mm Hg, and respiratory rate of 16 breaths/minute. He required an increase in inspired oxygen concentration from 40% to 60%. He had a moderate amount of thick, tan-colored tracheal secretions from the endotracheal tube. He did not have diarrhea. On physical examination, there were decreased breath sounds at the left lung base. There were no signs of exit-site erythema or drainage at the central venous catheter and right radial artery catheter insertion sites. A urinary catheter was in place. Peripheral blood leukocyte count was 17,600 cells/mm3. Chest imaging revealed a new left lower lung field opacity (Figure 50-1).

Figure 50-1.

Computed tomography of the chest showing left lower lobe consolidation.

What is the differential diagnosis of a new fever in an intensive care unit (ICU) patient?

The evaluation of a new fever in an ICU patient should always begin with a thorough review of the patient's history and a focused physical examination, rather than automatic ordering of microbiologic studies.1 After a differential diagnosis is formulated based on the history and physical examination, pertinent laboratory and radiologic studies should then be performed.

The differential diagnosis of a new fever in an ICU patient includes both infectious and noninfectious etiologies (Table 50-1).1, 2, 3 The most common infectious etiologies include hospital-acquired pneumonia (including ventilator-associated pneumonia), intravascular catheter-related bloodstream infection, catheter-associated urinary tract infection, surgical site infection, and Clostridium difficile infection. Infections unique to a neurologic/neurosurgical ICU include (1) superficial and deep surgical site infections that occur after neurosurgical procedures (eg, superficial wound infection after laminectomy or deep abscess after craniotomy) and (2) bacterial meningitis occurring after placement of internal and external ventricular catheters and lumbar catheters. Drug-related fever and intracranial hemorrhage are common noninfectious etiologies of fever in a neurologic/neurosurgical ICU.

Table 50-1.Common Etiologies of New Fever in a Patient in the Intensive Care Unit

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