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Fever in the
ICU
Fever, Late 1800s
◦Fever is the regulation of body
temperature at a higher level
◦Fever dangerous if too high or
prolonged
◦Antipyretic drugs should be
used only for high fevers or of
long duration
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Fever, Late 1800s
 Antipyretic
drugs widely available:
aspirin, other salicylates
 Many physicians advocated reducing
fever
 Fever considered harmful by-product
of infection, not host-defense
response
 Why? Perhaps because salicylates are
analgesic and antipyretic
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Fever
is energetically
costly
increasing
temperature 2-3ºC
increases energy
consumption 20%
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Mechanism of Protective Effect
 Enhanced
neutrophil migration
 Increased production of
antibacterial substances by
neutrophils
 Increased production of interferon
 Increased antiviral and antitumor
activity of interferon
 Increased T-cell proliferation
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Nosocomial Fevers
 Hospital-acquired
fevers
occur in one-third of all
medical inpatients
 Nosocomial fevers even
more common in the ICU
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Fever in the ICU
 ICU
patients have several underlying
medical/surgical conditions
 ICU patients undergo many invasive
diagnostic and therapeutic procedures
 Therefore, fever
in ICU patients must be
thoroughly and promptly evaluated to
discriminate infectious from noninfectious etiologies
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Diagnostic Approach
 Fever
is a non-specific sign
seen in inflammatory
processes that may be
◦infectious
◦noninfectious, including
neoplasm.
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Temp < 102º
Acute cholecystitis
 Acute MI
 Thrombophlebitis
 GI bleed

Acute pancreatitis
 Pulmonary
embolism or
infarct
 Viral hepatitis
 Uncomplicated
wound infection

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Temp 102º( Helps avoid
needless antibiotic therapy)
Cholangitis
 phlebitis
 Pericarditis
 Septic pulmonary
embolism
 Pancreatic abscess

Non-viral liver
disease: drug fever,
 Complicated wound
infection
 Bowel infarction

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Causes of Fever in the ICU




Intravenous-line
infections
Nosocomial pneumonia
Nosocomial sinusitis
Intraabdominal
infections




Urinary catheterassociated bacteriuria
Drug fever
Post-operative fever
Neurosurgical causes
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Systemic Inflammatory
Response Syndrome
 Definition
of SIRS
◦T > 38ºC or < 36ºC
◦HR > 90
◦RR > 20 or pCO2 < 32
◦WBC > 12 or < 4
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SIRS
 Often
noninfectious etiology
found:
◦ Pulmonary embolism
◦ Myocardial infarction
◦ Gastrointestinal bleed
◦ Acute pancreatitis
◦ Cardiopulmonary bypass
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Drug Fever
 Some
3-7% of fevers on an
inpatient medical service are drug
reactions
 History of atopy is a risk factor
 Patient may have been on the
“sensitizing medication” for days
to years
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Drug Fever
 On
physical patient looks
“inappropriately well” for
degree of fever
◦fever usually 102º to 104º
◦relative bradycardia
◦5-10% have rash
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Drug Fever
 Lab
tests show
◦ leukocytosis
◦ eosinophils on peripheral smear
(common)
◦ eosinophilia (low-grade)
◦ elevated ESR
◦ mildly elevated AST, ALT
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Common Causes of Drug Fever
 Antibiotics
 Antihypertensives
 Sleep
 Antidepressants
medications
 Antiepileptics
 Stool Softeners
 Diuretics
 Antiarrhythmics
 NSAIDs
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Rare Causes of Drug Fever
Digoxin
 Steroids
 Diphenhydramine
 Aspirin
 Vitamins
 Aminoglycosides
 Tetracyclines

Erythromycins
 Chloramphenicol
 Vancomycin
 Imipenim

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Postoperative Fever
Fever common post-operatively
 Most episodes noninfectious
 Probably due to intraoperative tissue
trauma with subsequent release of
endogenous pyrogens into the
bloodstream

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Postoperative Fever
72%
of fevers within the
48º after surgery are noninfectious
Wound, urinary tract, and
respiratory infections
occur later than 48º
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Postoperative Fever
 Empiric
antibiotics should be withheld
in patients with fever within 48º of
surgery if they lack a specific diagnosis
after thorough evaluation
 Continuing
perioperative prophylactic
antibiotics does not prevent infection,
only selects for resistant organisms
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Fever in Neurosurgical Patient

Most important causes are:
◦Wound infection
◦Meningitis, an infrequent
post-op complication,
especially after open-head
trauma
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Fever in Neurosurgical Patient
◦Can occur after any
intracranial procedure
◦Symptoms due to blood in
CSF
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Causes of High Fever (º)

Central fevers
◦ intracranial hemorrhage, head trauma,
infection, malignancy
◦ especially if the base of the brain or
hypothalamus affected
Infusion-related sepsis .
 Rarely, bacterial infection
 Drug fever (usually 102º to 106º)

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Causes of High Fever (º)
 Malignant
hyperthermia
◦ Rare genetic disorder, probably autosomal
dominant
◦ Incidence 1:15,000 in kids; less in adults
◦ Hypercatabolic reaction to anesthetic drugs
◦ Sustained muscle contraction .
◦ Tachycardia occurs in >90% of pts within 30
minutes
◦ Treated with dantrolene; mortality ~7%
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Causes of High Fever (º)

Malignant neuroleptic syndromes
◦ Confusion, hyperthermia, muscle
stiffness, autonomic instability
◦ Drugs implicated: phenothiazines,
thioxanthines, butyrphenones-antipsychotics, tranquilizers, and
antiemetics
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Intravenous-line Infections

Prevalence: 5% in ICU patients with triplelumen and pulmonary artery catheters*

Bloodstream infection is a serious
catheter-related complication: ~1020%
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Intravenous-line Infections
Look
for local signs of
infection: present in < 50%
Remove line if no other
source and T > 102º
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Scheduled Replacement?
 No
support for changing
lines every 3-5 days; change
only if unexplained fever or
catheter malfunction occurs
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Catheter-Associated Bacteriuria

Foley catheters
◦ Result in acquisition of bacteriuria
◦ Nearly always represents colonization, not
infection
◦ Pyuria often accompanies CAB,
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Catheter-Associated Bacteriuria
 Foley
+ high fever + bacteriuria
◦ does not necessarily mean urosepsis
◦ unless their is partial or total obstruction or
pre-existing renal disease
 Asymptomatic
CAB
◦ in normal hosts need not be treated
◦ in compromised hosts and chronically
immunosuppressed must be treated promptly
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Nosocomial Sinusitis
Bacteriology differs markedly from
community-acquired disease
 Gram-negative bacilli cause most cases in
intubated patients

Polymicrobial infection in upto 50% of cases,
reflecting ICU flora
 Paranasal sinusitis accounts for about 5% of
nosocomial ICU infections

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Nosocomial Sinusitis
Fever and leukocytosis often
present
 Purulent nasal discharge often
lacking
 Common in trauma and
neurosurgical units

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Nosocomial Sinusitis

Risk factors
◦
◦
◦
◦
◦


nasotracheal tubes
nasogastric tubes
nasal packing
facial fractures
steroid therapy
Diagnosis made easier with sinus CT,
which is more sensitive than plain films
Avoid prolonged nasotracheal intubation
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Intra-abdominal Infections

Suspect intra-abdominal abscess in
patients with prolonged post-operative
fever after abdominal surgery

cholecystitis and subsequent biliary sepsis
may complicate post-operative period
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Intra-abdominal Infections
Suspect antibiotic-associated colitis due to
Clostridium difficile in patients on broadspectrum antibiotics
 Fever and leukocytosis may be present prior
to diarrhea or abdominal symptoms
 Splenic or hepatic abscesses may complicate
other intra-abdominal infections (cholecystitis,
appendicitis) causing prolonged fevers

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Nosocomial Pneumonia
Almost all cases occur in mechanically
ventilated patients
 Signs are:

◦
◦
◦
◦
fever
leukocytosis
purulent tracheal secretions
new or worsening infiltrates on CXR
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Nosocomial Pneumonia



However, none of these are predictive of
pneumonia; nosocomial pneumonia remains
a clinical diagnosis
Can be confused with fibroproliferative
phase of ARDS, usually accompanied by lowgrade fever
Semi-quantitative BAL and protected-brush
specimen may be helpful, but not widely
available
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Summary
Fever in the ICU can have many infectious and
noninfectious etiologies
 Crucial to identify the precise cause as some of the
conditions in each groups are life-threatening, while
others require no treatment
 “Routine fever work-up” not cost-effective
 If initial evaluation shows no infection, antibiotics
should be withheld


Empiric antibiotics may be started in the unstable
patient, but stopped if infection is not evident later
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