Fever in the ICU

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Fever in the ICU

• J V Peter MD, DNB (Med), FRACP, Medical ICU
• Christian Medical College Hospital

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Introduction
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Introduction

• Fever is a common problem in the ICU
• Could be due to infectious and non-infectious
  causes
• Objective is to review a rational approach to the
  management of fever in ICU patients

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What is fever?

• Fever is a co-ordinated neuro endocrine,
  autonomic and behavioral response that is
  adaptive, and an essential part of the
  acute-phase response to immune stimulus or tissue
  injury
• Co-ordinated by the hypothalamus
• Neural input from peripheral thermoreceptors
• Humoral cues from inflammation or infection

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Benefits of fever

• Enhances parameters of immune function
• Improves antibody production
• Activates T-cells
• Produces cytokines
• Enhances neutrophil and macrophage function

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Benefits of fever - translated?

• Hot baths for malaria fever for treatment of
  syphilis
• Positive correlation between maximum temperature
  on the day of bacteremia and survival
• Temperature gt 38 C improved survival in patients
  with SBP
• In children with chicken pox, treatment with
  acetaminophen increased time to crusting of skin
  lesions

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The downside of fever

• Increased cardiac output
• Increased oxygen consumption
• Increased carbon-di-oxide production
• Increased basal metabolic rate

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The downside of fever-translated

• Poorer neurological outcomes in patients with
  stroke and traumatic brain injury who manifest
  temperature
• Fever poorly tolerated in patients with reduced
  cardio-respiratory reserve
• Maternal fever cause of fetal malformations as
  well as spontaneous abortions

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How to measure temperature in the critically ill
patient?
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With a thermometer of course !
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Measurement of temperature

• Peripheral temperature measurements
• Measured in the outer 1.6 mm of skin or mucus
  membranes
• Considered unreliable as influenced by
  environmental temperatures, mouth breathing etc.
• Examples oral temperature, axillary, skin
  temperature
• Core temperature measurements
• Not influenced by external factors
• More accurately reflects temperature in the
  internal organs
• Examples pulmonary, rectal, esophageal,
  urinary, tympanic

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Measurement of temperature

• Optimal site
• Pulmonary but invasive, need equipment
• Alternatives
• Tympanic easy but can be off by even 2O
• Urinary good alternative
• Rectal uncomfortable
• Oesophageal

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When do we say fever in the ICU patient?
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What is normal?

• Normal temperature
• 98.2O F (36.8OC)
• Diurnal variations of temperature with evening
  rise up to 100O F (37.8O C)

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So when do we get worried in the ICU?

• Society of Critical Care Medicine (SCCM) and
  Infectious diseases society of America recommend
  investigations in the ICU if temperature is
  above
• 101O F (38.3OC)

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Approach to fever in the ICU
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Approach to fever in ICU

• What are the causes of fever in ICU
• How do I act when I am see a temperature spike?
• What investigations do I send?
• How do I treat the fever?

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Approach to fever

• Patient who comes in with a febrile illness
• Cause of fever need to be ascertained

Patient in the ICU develops fever What is
causing this fever?
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Patient presenting to ICU with fever

• Patient with an obvious focus of infection
• Where is the focus?

Acute un-differentiated fever What is causing
this fever?
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The obvious focus

• Community acquired pneumonia
• Acute CNS infection
• Urinary tract infection
• Abdominal focus of infection
• Wound infection / Pus collections
• Trauma with infection

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The obvious focus

• And why do they come to the ICU
• Ventilatory support respiratory failure
  pneumonia
• Hemodynamic support shock
• Renal replacement therapy renal failure, severe
  acidosis
• Monitoring, Neurological dysfunction, Hematologic

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Approach to fever

• Patients presenting with a febrile illness

Patient developing fever in the ICU
Is there a focus of infection?
Acute undifferentiated fever
v
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Acute undifferentiated fever

• Where no specific focus identified
• Look for specific clues to guide in the diagnosis

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Acute undifferentiated fever

• Fever with thrombocytopenia
• Fever with hepato-renal dysfunction
• Fever with pulmonary renal syndrome
• Fever with altered sensorium

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Fever with thrombocytopenia

• Fever with thrombocytopenia
• Malaria (notably falciparum)
• Dengue
• Leptospirosis
• Rickettsial infections
• Viral fevers

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Fever with hepato-renal dysfunction

• Fever with hepato-renal dysfunction
• Malaria (falciparum)
• Leptospirosis
• Scrub typhus
• Fulminant hepatic failure with hepatorenal

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Fever with pulmonary-renal dysfunction

• Fever with pulmonary-renal dysfunction
• Malaria (falciparum)
• Leptospirosis
• Scrub typhus
• Hantavirus infection
• Severe legionella / pneumococcal pneumonia

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Fever with altered sensorium

• Fever with altered sensorium
• Malaria cerebral malaria
• Encephalitis
• Meningitis
• Typhoid fever
• Septic encephalopathy
• Brain abscess

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Approach to fever

• Patients presenting with a febrile illness

Patient developing fever in the ICU
Is there a focus of infection?

• Acute undifferentiated
• fever

v
v
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Patient developing fever in the ICU

• Infectious causes
• Where is the focus?

Non-infective causes What is causing this
fever?
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Infectious causes of fever whilst in ICU

• Ventilator associated pneumonia
• Catheter related blood stream infections
• Urosepsis
• Intra-abdominal infections
• Sinus infections
• Diarrhoea

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Infectious causes of fever whilst in ICU

• Fungal infections including candidemia
• Surgical wound infections
• Acalculous cholecystitis
• Endocarditis
• Meningitis

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Non-infectious causes of fever in ICU
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Summary of approach to fever in ICU

• Patients presenting with a febrile illness

Patient developing fever in the ICU
Is there a focus of infection?
Infective Causes

• Acute undifferentiated
• fever

Non-infective Causes
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Approach to fever in ICU

• What are the causes of fever in ICU v
• How do I act when I am see a temperature spike?

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How do I act when there is a temperature spike?
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One temperature spike

• Should I be worried?

• YES
• In an immunocompromised patient
• If hemodynamic instability
• Decreasing UOP
• Increasing lactate
• Worsening conscious state
• Falling platelet counts
• Worsening coagulopathy
• NO
• Small spike
• No hemodynamic instability
• Carefully examine clinically for an obvious focus
  of infection

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What investigations to send?
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What investigations should I send?

• 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

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What investigations should I send?

• 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

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What investigations should I send?

• Do not forget about non-infective causes
• Acute Lung injury/ARDS, Aspiration
• Deep venous thrombosis, thrombophlebitis
• Drug fever
• Decubitus ulceration

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How do I treat the fever?
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With respect ?
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How do I treat?

• Difficult question
• Do I use antipyretics?
• When to administer or change antibiotics?

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How do I treat?

• Do I use antipyretics?
• Yes in patients with Neurological disorders
• Poor cardio- respiratory reserve

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How do I treat?

• When to administer or change antibiotics?
• Generally in an unstable patient choose to
  treat with broad spectrum antibiotics and pull
  back depending on cultures clinical response

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Summarizing
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Recap

• Enumerated causes of fever in the ICU
• Useful to have a systematic approach to fever
• Investigate treat appropriately

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