What are the causes of hyperthermia (elevated body temperature)?

From the Guidelines

Elevated body temperatures, or fevers, in the context of acute ischemic stroke are primarily caused by infections, inflammatory conditions, or complications such as pneumonia, urinary tract infections, or sepsis, and the source of any fever should be ascertained and treated accordingly. The management of temperature in patients with acute ischemic stroke is crucial, as hyperthermia is associated with poor neurological outcome, possibly secondary to increased metabolic demands, enhanced release of neurotransmitters, and increased free radical production 1.

Causes of Elevated Temperature

• Infections such as viral illnesses, bacterial infections, and parasitic diseases
• Inflammatory conditions like rheumatoid arthritis and inflammatory bowel disease
• Complications such as pneumonia, urinary tract infections, or sepsis
• Certain medications may cause drug fevers as a side effect
• Heat-related illnesses such as heat exhaustion or heat stroke

Management of Elevated Temperature

• Seeking and treating the source of fever is reasonable, as stated in the guidelines for the early management of adults with ischemic stroke 1
• Administration of antipyretic medication can still be a reasonable approach to relieve the symptom of discomfort associated with hyperthermia, although the evidence for its benefit in improving functional outcome and/or survival is limited 1
• Measures to achieve normothermia or prevent hyperthermia include both pharmacological and mechanical interventions, but the current evidence does not support routine prevention of hyperthermia with antipyretics in normothermic patients 1

Treatment

• For most mild fevers, treatment includes rest, hydration, and over-the-counter medications like acetaminophen or ibuprofen
• However, fevers above 103°F (39.4°C), lasting more than three days, or accompanied by severe headache, stiff neck, breathing difficulty, or confusion warrant immediate medical attention to identify and treat the underlying cause 1

From the Research

Causes of Elevated Temperatures

• Elevated body temperature, or fever, can be caused by a wide range of disease conditions and is a common finding in intensive care, affecting up to 70% of patients in the intensive care unit (ICU) 2
• The causes of fever in the ICU are multifactorial, and it can be due to a number of infective and noninfective etiologies 2
• 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 2

Effects of Fever

• Fever is associated with a wide range of cellular, local, and systemic effects, including multiorgan dysfunction, systemic inflammation, poor neurological recovery, and an increased risk of mortality 2
• Elevated temperatures can exert profound effects on cell signaling and gene expression patterns, which have important consequences for innate immune function and cell injury, apoptosis, and recovery 3

Management of Fever

• The use of antipyretic drugs to suppress fever during infection remains a controversial topic within the literature 4
• Some studies have demonstrated improved patient outcomes following antipyretic administration, while others have demonstrated increased mortality risk associated with antipyretics and/or demonstrated fever's benefits during infection 4
• The combination of acetaminophen and ibuprofen has been shown to produce significantly greater fever control than acetaminophen alone, with trends favoring the combination over ibuprofen alone and ibuprofen over acetaminophen alone 5