Fever in ICU

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