Fever is a common problem in the ICU, occurring in 30-70% of patients. It can be caused by infections, non-infectious factors, or a combination. A thorough evaluation including blood tests, imaging, and cultures is important to determine the cause. Common infectious causes include ventilator-associated pneumonia, catheter-related bloodstream infections, and urinary tract infections. Non-infectious causes include drug reactions, transfusions, and environmental factors. Prompt treatment of the underlying cause is key to avoiding adverse outcomes in critically ill ICU patients experiencing fever.

1. FEVER IN ICU
Surg SLt LO Majolagbe
DEPT OF ANAESTHESIA/ICU
NNRH OJO

2. OUTLINE
 INTRODUCTION
 EPIDEMIOLOGY
 CAUSES
 EVALUATION
 MANAGEMENT

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.

9. Introduction

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)

16. Non Infectious causes

17. Non Infectious causes - Drugs

18. Non Infectious causes - Drugs

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

23. Other Non – Infectious causes
 Hyperthermic Syndromes
 Neuroleptic Malignant Syndrome
 Malignant Hyperthermia
 Environmental (heatstroke) – Tropics
 Serotonin Syndrome
 Endocrine: Thyrotoxicosis, Pheochromocytoma and
Adrenal Crisis

24. MH - NMS

25. NMS
 Neuroleptic Malignant Syndrome (3 major or 2 major
+ 4 minor)
 Major Criteria: Insidious onset of hyperthermia,
Muscle rigidity, Elevated CPK
 Minor criteria: Tachycardia, Tachypnea, Altered
sensorium, Abnormal BP, Leukocytosis.

26. Infectious causes of fever
whilst in ICU
 Ventilator associated pneumonia
 Catheter related blood stream infections
 Urosepsis
 Intra-abdominal infections
 Sinus infections
 Diarrhea

27. Infectious causes
 Community acquired pneumonia
 Acute CNS infection
 Urinary tract infection
 Abdominal focus of infection
 Wound infection/ Pus collections

28. Infectious causes
 Fungal infections including candidemia
 Surgical wound infections
 Acalculous cholecystitis
 Endocarditis
 Meningitis

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%).

30. Ventilator Associated Pneumonia

31. System

32. System

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

34. Evaluation

35. Head to Toe Approach

36. Evaluation

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.

43. External cooling techniques

44. Conclusion
 Prompt and adequate evaluation and treatment is
key in critically ill patients with fever to avoid further
deterioration and adverse outcomes.

45. THANK YOU FOR YOUR RAPT
ATTENTION