Fever in the ICU Christopher Kia. Outline Definition of fever Why fever in the ICU is important Temperature measurement Etiology - infectious and noninfectious.

Fever in the ICUFever in the ICU

Christopher KiaChristopher Kia

OutlineOutline

•Definition of fever

•Why fever in the ICU is important

•Temperature measurement

•Etiology - infectious and noninfectious causes

•Diagnostic approach

•Definition of fever

•Why fever in the ICU is important

•Temperature measurement

•Etiology - infectious and noninfectious causes

•Diagnostic approach

Definition of FeverDefinition of Fever

•Normal body temperature = 37.0°C, varying with the time of day and measurement method

•Definition of fever is arbitrary

•Fever = body temperature of 38.3°C or higher, while acknowledging that this threshold may need to be lowered in immunocompromised patients (ACCCM/IDSA joint task force definition)

•Normal body temperature = 37.0°C, varying with the time of day and measurement method

•Definition of fever is arbitrary

•Fever = body temperature of 38.3°C or higher, while acknowledging that this threshold may need to be lowered in immunocompromised patients (ACCCM/IDSA joint task force definition)

Why Fever in the ICU is Important (1)

Why Fever in the ICU is Important (1)

•Fever complicates 70% of all ICU admissions

•Often represents a serious underlying condition, but may propagate a series of unnecessary investigations and lead to inappropriate antibiotic use

•Fever is associated with increased length of stay in ICU, increased cost of care, poorer outcomes in certain patient groups e.g. traumatic head injury, SAH, pancreatitis

•Fever complicates 70% of all ICU admissions

•Often represents a serious underlying condition, but may propagate a series of unnecessary investigations and lead to inappropriate antibiotic use

•Fever is associated with increased length of stay in ICU, increased cost of care, poorer outcomes in certain patient groups e.g. traumatic head injury, SAH, pancreatitis

Why Fever in the ICU is Important (11)

Why Fever in the ICU is Important (11)

•In one observational study of 24,204 adult ICU admissions, high fever (≥39.5°C) alone was associated with a significant increase in mortality (20% vs 12%)

•Clinical assessment of ICU patients is often hampered by invasive medical technology e.g. CRRT and ECMO can modify the febrile response or mask it completely

•In one observational study of 24,204 adult ICU admissions, high fever (≥39.5°C) alone was associated with a significant increase in mortality (20% vs 12%)

•Clinical assessment of ICU patients is often hampered by invasive medical technology e.g. CRRT and ECMO can modify the febrile response or mask it completely

Temperature MeasurementTemperature Measurement

•Conventional: intravascular, intravesical, rectal, oral, cutaneous, tympanic

•Axillary, temporal artery, tympanic and chemical dot monitors are inaccurate in critically ill patients

•Gold standard: thermistor on a pulmonary artery catheter (infrequently placed and may be unreliable if PAC used for rapid volume administration)

•Conventional: intravascular, intravesical, rectal, oral, cutaneous, tympanic

•Axillary, temporal artery, tympanic and chemical dot monitors are inaccurate in critically ill patients

•Gold standard: thermistor on a pulmonary artery catheter (infrequently placed and may be unreliable if PAC used for rapid volume administration)

EtiologyEtiology•Infectious and Noninfectious causes

•Distinguishing between both causes can be challenging, requires careful clinical assessment, both causes may coexist

•Fever ≥41.1°C usually noninfectious in origin

•Temperatures between 38.9 and 41.0°C can be assumed to be infectious in origin

•Infectious and Noninfectious causes

•Distinguishing between both causes can be challenging, requires careful clinical assessment, both causes may coexist

•Fever ≥41.1°C usually noninfectious in origin

•Temperatures between 38.9 and 41.0°C can be assumed to be infectious in origin

Infectious causes of fever

Infectious causes of fever

Common causes Other causesBacteraemia

Intravascular catheter-related

infection

Surgical site infection

Ventilator-associated

pneumonia (VAP)

CellulitisCholangitis

DiverticulitisEmpyema

EndocarditisIntra-abdominal abscess

MeningitisMyonecrosis

Necrotising fasciitisPseudomembranous colitis

Septic arthritisSinusitis

ThrombophlebitisUrinary tract infection

Viral

Noninfectious causes of fever

Noninfectious causes of fever

Important causes Other causes

Acalculous cholecystitis

Adrenal insufficiency

Benign post-operative fever

Drug fever

Pancreatitis

Thyroid storm

Transfusion reaction

Acute respiratory distress syndrome (late)Burns

Drug overdose (e.g. aspirin, anticholinergic drugs)

Drug withdrawalGout

Heat strokeIntracranial haemorrhage

Ischaemic colitisMalignancy

Malignant hyperthermiaMyocardial infarction

Neuroleptic malignant syndromePheochromocytoma

SeizuresSerotonin syndrome

Thromboembolic diseaseVasculitis

Diagnostic Approach to New

Onset of Fever in

ICU

Diagnostic Approach to New

Onset of Fever in

ICU

Serum markers (1)Serum markers (1)•CRP: Acute phase protein secreted by liver,

marker of inflammation, can be affected by significant liver disease, more sensitive marker of sepsis than either body temperature or WCC but lacks specificity

•Procalcitonin: More specific marker of bacterial infection than CRP, levels rise earlier than CRP and correlate more closely to severity of disease, however its utility in distinguishing infection from other causes of SIRS in older patients conflict in studies

•CRP: Acute phase protein secreted by liver, marker of inflammation, can be affected by significant liver disease, more sensitive marker of sepsis than either body temperature or WCC but lacks specificity

•Procalcitonin: More specific marker of bacterial infection than CRP, levels rise earlier than CRP and correlate more closely to severity of disease, however its utility in distinguishing infection from other causes of SIRS in older patients conflict in studies

Serum markers (11)Serum markers (11)•An endotoxin activity assay has shown

encouraging results, excluding Gram-negative infections with a 98.6% negative predictive value in one observational study

•Use of both procalcitonin and this endotoxin activity assay are supported by American College of Critical Care Medicine and Infectious Diseases Society of America as adjunctive tools in discriminating infection from other causes of SIRS

•An endotoxin activity assay has shown encouraging results, excluding Gram-negative infections with a 98.6% negative predictive value in one observational study

•Use of both procalcitonin and this endotoxin activity assay are supported by American College of Critical Care Medicine and Infectious Diseases Society of America as adjunctive tools in discriminating infection from other causes of SIRS

RecapRecap

•Definition of fever

•Why fever in the ICU is important

•Temperature measurement

•Etiology - infectious and noninfectious causes

•Diagnostic approach and management

•Definition of fever

•Why fever in the ICU is important

•Temperature measurement

•Etiology - infectious and noninfectious causes

•Diagnostic approach and management

QUESTIONS?QUESTIONS?