3. Introduction
Fever is a common problem in the ICU
It could be infections, non-infectious or mixed
4. Definition
It is defined as a coordinated neuro-endocrine,
autonomic and behavioral response that is adaptive
and an essential part of acute-phase response to
immune stimulus or tissue injury.
5. Definition
It is coordinated by the Hypothalamus (Thermostat).
Neural input from peripheral thermoreceptors.
Humoral stimulus from inflammation or infection.
Hypothalamic set point – 37 °C. Varies through the
course of the day. Rises up by 0.5 as the day goes by
(evening).
6. What is a fever?
Society of Critical Care Medicine(SCCM) and
Infectious disease society of America(IDSA):
Normal : 98.2 °F (36.8 °C)
Elevation in body temperature above normal range
from increase in temperature regulatory set point :
99.5 - 100.9 °F (37.5 – 38.2 °C)
Hyperpyrexia:
104 - 106.7 °F (40 – 41.5 °C).
Hyperthermia (Set point not affected).
Hypothermia 95 °F (35 °C)
7. Fever of Unknown Origin (FUO)
Fever on several occasions, persisting without
diagnosis for at least 3 weeks in spite of at least 1
week’s investigation in hospital.
8. Introduction
30% of medical patients will be febrile during their
stay in ICU.
90% of critically ill patients with severe sepsis will
experience fever during their stay in ICU.
The acquisition of fever in the ICU is associated with
adverse outcomes.
10. Epidemiology
The incidence of fever in the ICU ranges from 28%
to 70%.
Infectious as well as noninfectious etiologies
contribute almost equally to the causation of febrile
episodes.
35-55% are infectious.
At least 50% of febrile episodes are non-infectious.
11. Merits of Fever
It helps to rid of the host from invading pathogens:
e.g. Plasmodium species, Spirochaetes, Bacteria such
as Streptococcus pneumoniae and Treponema
pallidum.
Enhances parameters of immune function
Improves antibody production
Activates T-cell
Produces cytokines
Enhances neutrophil and macrophage function
12. Demerits of Fever
Increase in cardiac output
Increase oxygen consumption (10% per 1°C)
Increase carbon dioxide production
Poor neurological outcomes in patients with stroke
and traumatic brain injury
Increase basal metabolic rate
Fever is poorly tolerated in patients with reduced
cardio-respiratory reserve
13. Fever versus hyperthermia
Fever: resetting of the thermostatic set-point in the
anterior hypothalamus and the resultant initiation of
heat-conserving mechanisms until the internal
temperature reaches the new level
If acute (and less commonly chronic), infection unless
proven otherwise
Hyperthermia: an elevation in body temperature that
occurs in the absence of resetting of the hypothalamic
thermoregulatory center
Usually not mediated by infectious diseases
14. Pathogenesis
Pyrogens (endogenous and exogenous) trigger fevers
via release of prostaglandin E2 hypothalamic
stimulation vasoconstriction, then shivering
temp rise
Endogenous: IL1, 6,8, TNF, IFNa,b,g arachidonic
acid pathway activated
Can be released in collagen vascular, malignancy
Exogenous: i.e. LPS binds to lipopolysaccharide
binding protein release of IL-1
Typically infectious
15. Causes
Infectious, Non – Infectious or Both.
Most noninfectious disorders usually do not lead to a
fever >38.9°C (102°F)
19. Non Infectious causes - Drugs
Remember to always document drug related fever as
an allergy!
20. Fever Associated With Drug Withdrawal
Fever may occur several hours or days after
discontinuation of a medication.
Patient will have Fever, Tachycardia, Diaphoresis,
Hyperreflexia.
Offenders are Alcohol, Opiates, Barbiturates
Benzodiazepines.
21. Febrile Transfusion Reactions
Complicate about 0.5% of blood transfusions.
It is more common following platelet transfusion.
It usually begin within 30 mins to 2 hrs. after a blood
product transfusion.
The fever generally lasts between 2 to 24 hrs. and
may be preceded by chills.
22. Other Non – Infectious causes
ICU Environment
Specialized Mattresses
Hot Lights
Cardiopulmonary Bypass
Peritoneal Lavage
Dialysis
Post Op fever
29. Ventilator Associated Pneumonia
Pneumonia in a patient who has been on ventilator
for >48 hours
Risk of VAP highest early in the course of hospital
stay
3%/day for first 5 days
2%/day from 5 to 10 days &
1%/day thereafter
Mortality in Pt with VAP twice than pts without VAP
(33 and 50%).
33. Evaluation
Is this a complication of the underlying reason for
admission?
Untreated, relapsed, or metastatic focus of infection •
Post-surgical infection (surgical site infection, intra-
abdominal abscess)
Is this a separate nosocomial process? • Hospital-
acquired (VAP, aspiration) • CA-UTI • Catheter-
Related Bloodstream Infection (CRBSI) • Clostridium
Is this non-infectious? • Drug fever • Others
37. Evaluation
Bloods –counts, procalcitonin
Imaging – CXR scans as indicated
(abdomen, sinus, CT brain)
Cultures as appropriate- ETA, BAL,
Urine, Blood cultures (peripheral
and through lines), cultures from
pus, wound etc., Stool for
clostridium
38. Evaluation
Assess if lines are “old” and if there is
any evidence of line sepsis – re-site line
if indicated
Change urinary catheter
May need NG change- if sinus infection
suspected
39. Procalcitonin
Procalcitonin can be used as an adjunctive to
microbiological tests for identifying infective diseases.
SIRS 0.6 to 2.0 ng/mL
Severe sepsis 2 to10 ng/mL
Septic shock ≥10 ng/mL
Viral infections, recent surgery, and chronic
inflammatory states are not associated with any
increment
40. C-Reactive Protein
Originally named for its ability to bind the C
polysaccharide of Streptococcus pneumoniae
CRP is mostly synthesized by hepatocytes in response
to IL-6, IL-1 and TGF-ß. The plasma level of CRP
rises within 6 hrs., double every 8 hrs. and peak at
50 hrs. in systemic inflammatory stimulus
41. C-Reactive Protein
Normal level in healthy adults is <10 mg/L.
May rise up to a 1000-fold in response to an
inflammatory stimulus.
42. Management
Relative risk-benefits should be evaluated in
individual patient.
Treat with acetaminophen if: Temperature > 38°C
External cooling useful in cases of hyperthermia
rather than fever.
44. Conclusion
Prompt and adequate evaluation and treatment is
key in critically ill patients with fever to avoid further
deterioration and adverse outcomes.