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Physical Exam Clues to Infectious Diseases
and Their Mimics in Critical Care
Yehia Y. Mishriki
Department of Medicine, Lehigh Valley Hospital Network, Allentown, Pennsylvania, U.S.A.“Life is short, art long, opportunity fleeting, experience treacherous, judgment difficult.”
—Hippocrates(460 to 400 B.C.)
Under the best of circumstances, the physical examination (PE) of an ICU patient is quite
challenging. To make matters more difficult, many physical findings are neither specific nor
sensitive. What have been touted as “pathognomonic” findings are rarely, if ever, so. The astute
physician must always consider that a given physical examination finding may be due to more
than one disease entity. Premature closure and availability bias can further trip up the unwary
clinician. As with various clinical syndromes, physical examination findings in infected patients
can be mimicked by a variety of infectious and noninfectious diseases. The table that follows lists
many of the physical examination findings one may encounter in the infected ICU patient along
with their noninfectious mimics and hints to help distinguish them apart.
System PE ID findings Noninfectious mimics Diagnostic features
Fever 1. Usually the sine
qua non of
infection
l Drug/drug withdrawal fever
l Central fever/subarachnoid
hemorrhage
l Periodic fever syndromes
l Sarcoidosis
l Neoplasms (lymphoma,
renal cell center)
l Autoimmune diseases
(i.e., SLE)
l Neuroleptic malignant
syndrome
l Malignant hyperthermia
l Immune reconstitution in HIV
l Reaction to blood products
l Jarisch–Herxheimer reaction
l Tumor lysis syndrome
l Pancreatitis
l Organ transplant rejection
l Venous thrombosis/pulmonary
embolism/fat embolism
l Gout
l Myocardial infection
l Stroke
l Adrenal insufficiency
l Acalculous cholecystitis
l Postoperative
l Aspiration syndromes
l Atrial myxomaNoninfectious causes of fever
must always be considered
in a patient with fever and no
obvious source of infection,
especially in the proper
clinical setting.
Rash and/or eosinophilia
suggest a drug fever.
Relative bradycardia may be
present, but this may be
found in infectious causes
as well.