Fever

Li Shuang

Definition

An elevation of core body temperature

above the normal range

Normal temperature

• Normal temperature 36~37℃

• Core body temperature varies throughout the day

<1 ℃

• Fever:

Oral>37.3 Rectal> 37.6 difference>1.2℃ ℃ ℃

Pathogenesis

Anterorhypothalamus

thermostat

Heat gain effector system

Heat loss effector system

Organ:skin

Organ: skeletal muscle, liver

Set-point theory

pathogenesis

Endogenous pyrogens

Exogenous pyrogensBacteria ,viruses,

immune complexes

Interleukin ,TNFInterferon

Fever

Hypothalamic set point

Disruption of hypo-thalamic thermostat

Production of heat↑ Loss of heat↓

Failure of body`s temperature-regulating mechanisms

•CNS disease•Inherited malignant• hyperthermia

•Strenous exercise or other stress•Chills•Thyrotoxicosis

•Heat stroke•Heart failure•Skin conditions

Etiology and classification

• Infective fever

various microorganisms , such as bacteria ,

virus, mycoplasma, fungus

• None-infective fever

Absorption of necrotic substances: injury; ischemic necrosis;

Endocrine and metabolic disturbances: hyperthyroidism and dehydration

Decreased elimination of heat from skin: heat failure

Dysfunction of central heat regulation:

a: Physical, as heat stroke;

b: chemical , as barbiturate poisoning;

c: Mechanical, as cerebral hemorrhage.

Dysfunction of vegetative nervous system; as the cases of sympathetic

overactivity.

Etiology and classification

The effects of Fever

• Enhanced neutrophil migration

• Increased production of antibacterial substances by

neutrophils

• Increased production of interferon

• Increased antiviral and antitumor activity of

interferon

• Increased T-cell proliferation

• Decrased growth of microorganisms in iron-poor

environment

Clinical manifestation

• Grade of fever

Hyperthermia fever: over 41 ℃

High fever: 39.1~41 ℃

Moderate fever: 38~39 ℃

Low grade fever: 37.3~38℃ 37℃

38℃

39℃

40℃

41℃

• The clinical course and character of fever

Clinical manifestation

37℃

onset

persistence

subsidence

Patterns of FeverContinued Fever

•Above normal throughout the day

•Fluctuate less than 1 in 24 hours℃

•Lobar pneumonia , typhoid

• Remittent Fever

Patterns of Fever

Temperature above 39℃

Fluctuate more than 2 in 24 hours℃

Sapraemia , acute infectious endocarditis

• Intermittent Fever

Patterns of Fever

•Episodes of fever separated by days of normal temperature

•Malaria

• Undulant Fever

Patterns of Fever

•Increase to 39 in several days and then slowly return to the ℃

normal

•Brucellosis , tumor

• Irregular Fever

Patterns of Fever

•No regular pattern

•tuberclosis

Caution

• Using Antibiotic

• Using antipyretic or glucocorticoid

• Individual difference. e.g. medically frail

elderly people with pneumonia

Associated symptoms

• Chills or rigor

acute infective disease, transfusion reaction

• Lymph node enlargement

infectious mononucleosis , lymphoma , leukemia

• Enlargement of liver and spleen

infectious mononucleosis . lymphoma. Leukemia .hepatitis

• Coma

cerebritis . Cerebral hemorrhage

Associated symptoms

Associated symptoms

• Rash

measles . Connective tissue diseases . Drug fever

History taking

• When, acute or chronic, fever grade, pattern

• Chilly, sweating

• Systemic symptoms: respiratory system, digestive system, urinary system

• General condition

• Treatment course (antibiotic? antipyretic?)

Diagnostic points

• Other symptoms besides Fever

• Duration and magnitude of Fever

• Close contact with similar illness

• Occupational , travel , recreational exposure

• History of disease

• Current medication

• Allergy

Case

Repeated chill then fever

bacteremia

Local infectionSeek for Infection site

History taking and examination

Case 2Patient with hepatitisChill and feverleukocytosis

Local infection

abdominal infection?

ultrasonic testing 1st normal

1week, hiccup ,position change aggravation

diaphragm subphrenic abscess

Summary

• Definition

• Pathogeneses

• Etiology

• Clinical course

• Patterns

• Associated symptoms

• Diagnosis points

Thanks !