fever, HUO, & hyperthermia lecture

clin med 1

measuring temperature methods

peri

fever definition

an elevation of body temp of .37.2 C/98.9 F in the morning and >37.7 C/00.9F in the evening in conjunction w/ an increase in the hypothalamic set point due to pyrogenic cytokines

fever of unknown origin

temperatures > 38.3⁰C/101⁰F on two or
more occasions and an illness duration of > 3 weeks, with no known
immunocompromised state and no evidence of cause on diagnostic testing

hyperpyrexia

fever > 41.5⁰C/106.7⁰F, very uncommon

hyperthermia

an uncontrolled increase in body temperature that exceeds the body’s ability to lose heat without a change in the hypothalamic set
point

etiology of fevers

viral illness and self-limiting

common causes of FUO

• atypical presentation of common infections

• neoplasms

• non-infectious inflammatory disease

hyperthermia is always caused by

Exogenous heat exposure (heat stroke)
• Endogenous heat production (drug-induced, thyroid storm)

how to distinguish b/t fever & fuo

history of

• heat exposure

• certain drugs

• med history

• relief w/ antipyretics

degree of temp

skin examination

malignant hyperthermia

Inherited autosomal dominant genetic mutation of ion channels on skeletal
muscle that results in unregulated calcium release
• Upon administration of general anesthesia and/or succinylcholine acute,
uncontrolled metabolism of skeletal muscle occurs due to prolonged contraction
• Life-threatening condition
• Occurs across all ethnic groups, more common in males and children

tx for malignant hyperthermia

dantrolene

• interferes w/ calcium release w/in skeletal muscle cells

common infectious causes of fever

• viral/bacterial Gastroenteritis
  • Acute appendicitis
  • Acute diverticulitis
  • Acute cholecystitis
  • Acute pancreatitis
  • Acute cystitis
  • Acute pyelonephritis
  • Acute bacterial prostatitis
  • Acute epididymitis
  • PID

• Acute otitis media
  • URI
  • Acute bacterial sinusitis
  • Pharyngitis
  • Viral (rhinoviruses, coronaviruses, EBV)
  • Bacterial (GABHS)
  • Tonsillitis
  • Influenza
  • Pneumonia
  • Viral
  • Bacterial
  • COVID-19
  • Meningitis
  • Bacterial
  • viral

  
  

tx of fever

Antipyretics for relief of fever symptoms
• NSAIDs, acetaminophen
• Aspirin should be AVOIDED in pediatric population due to risk of Reye’s syndrome
• Other conservative measures
• Fluids
• Rest
• Reassurance
• Further treatment, if indicated, is dependent on the source
• Antibiotics or antivirals
• Should be tailored when possible to avoid drug resistance
• Steroids
• Surgical procedure

FUO work up

A thorough H&P is essential
• Ensure that the fever is “real”
• Associated symptoms will guide you in the right direction
• Labs
• Diagnostic Imaging
• Eliminate meds that are associated with drug fever
• Specialty involvement: ID, Rheum, Heme-Onc, Pharm

tx of hyperthermia

Requires emergent treatment to avoid complications
• Must discontinue the causative agent
• Continuous core temperature monitoring
• Rectal probe
• IV fluids
• Initiate cooling

complications of fever and hyperthermia

Febrile seizure
• Mental status changes
• Irreversible protein denaturation and resultant brain damage can
occur when temperature exceeds 41.1⁰C/106⁰F