From the Guidelines
A fever in the ICU is defined as a core body temperature of 38.3°C (101°F) or higher, as per the Society of Critical Care Medicine and the Infectious Diseases Society of America guidelines 1. This definition is crucial in the ICU setting, where patients are often critically ill and require close monitoring of their vital signs. The threshold of 38.3°C is slightly higher than the standard definition of fever in non-ICU settings, which helps to reduce false positives in critically ill patients.
Key Considerations in Fever Management
- The presence of fever in ICU patients often indicates infection, inflammation, drug reactions, or other serious conditions, and therefore, its underlying cause should always be investigated promptly 1.
- Not all fevers require treatment with antipyretics, and the routine use of antipyretic medications for the specific purpose of reducing temperature is not recommended 1.
- However, in selected cases where patients or family members value reducing temperature for symptomatic relief, antipyretic medications such as acetaminophen 650mg every 6 hours as needed may be used 1.
- Physical cooling methods such as cooling blankets may be used for temperatures exceeding 39.5°C (103.1°F).
Importance of Investigating the Underlying Cause
- Blood cultures, urine cultures, and imaging studies should be obtained before starting empiric antimicrobial therapy to determine the underlying cause of fever 1.
- Fever in ICU patients increases metabolic demands and oxygen consumption, which can be particularly problematic for patients with limited cardiopulmonary reserve, making temperature management an important aspect of critical care 1.
From the Research
Definition of Fever in the ICU
- Fever is defined as an increase in body temperature above 38.3°C 2 or a core body temperature of >38.3 degrees C or 101 degrees F 3.
- Fever is a common finding in intensive care, affecting up to 70% of patients in the ICU 4 or up to 90% of patients admitted to the intensive care unit 2.
Key Characteristics of Fever in the ICU
- Fever can be due to a number of infective and noninfective etiologies 4.
- About 50% of fevers in the ICU are due to infectious causes 3.
- Temperatures between 102 degrees F-106 degrees F are more likely to be due to infection 3.
- Fever should be distinguished from hyperthermia as antipyretics are ineffective in the latter 3.
Clinical Implications of Fever in the ICU
- Fever is associated with increased length of stay in intensive care unit and with a worse outcome in some subgroups of patients (mainly neurocritically ill patients) 2.
- Fever can increase oxygen consumption in unstable patients, but it can also activate physiologic systems that are involved in pathogens clearance 2.
- The production of fever represents a complex physiological, adaptive host response that is beneficial for host defense and survival but can be maladaptive and harmful if left unabated 4.