FEVERİstanbul University Cerrahpaşa Medical Faculty

Department of Pediatrics

Prof. Dr. Ayşe Güler EROĞLU

The purpose of the lesson Learning

The definition of fever The control mechanisms of body

temperature The circadian rhythm of body temperature Physiological factors that may increase body

temperature The pathogenesis of fever Normal and abnormal body temperature Etiologic classifications of fever Treatment of the fever (in high–risk patients)

Definition of fever

Fever is an elevation of body temperature mediated by an increase of the hypothalamic heat regulatory set-point.

Control mechanisms of body temperature

Hypothalamic thermoregulatory center controls body temperature by Peripheral cold and warm neuronal

receptors Temperature of blood circulating in

the hypothalamus

Control mechanisms of body temperature  Heat generation

Increased cell metabolism Muscle activity Involuntary shivering

Heat conservation Vasoconstriction

Heat loss Obligate heat loss (evaporation,

radiation, convection, conduction) Vasodilation Sweating

Human is “homoioterm” (has constant temperature)

Normal core body temperature 37o

C within a narrow range of 1-1.5o

C. Axillary temperature may be 1o C

lower than core temperature -cutaneous vasoconstriction

Oral temperature may be falsely lowered owing to rapid respirations.

Circadian rhythm of body temperature Early morning temperature is low Highest level occurs at 4.00-6.00

PM

Physiological factors may increase body temperature

Physical activity (maximum 1.1o C) Digestion Changes in environmental

temperature After ovulation in women First three months of gestation Exicement

Important The body temperature should be

measured at bed rest or physically inactive

for 30 minutes before the temperature is taken

within one hour after a meal prior intake of cold or hot foods

Before 6 years old - rectal or axillary After 6 years old - oral temperature

measurement

Pathogenesis of fever

Various infectious, immunologic or toxin-related agents (exogenous pyrogens) induced the production of endogenous pyrogens by host inflammatory cells.

These endogenous pyrogens are cytokines, such as interleukins (IL-1, IL-1, IL-6), tumor necrosis factors (TNF-, TNF-), and interferon- (INF).

Pathogenesis of fever

Endogenous pyrogenic cytokines directly stimulate to hypothalamus to produce prostoglandin E2, which then resets the temperature regulatory set point

Endogenous pyrogens induce fever within 10-15 min. Whereas the febril response to exogenous pyrogens has a delayed onset requiring the synthesis and release of pyrogenic cytokines (60-90 min).

Normal Low grade

fever

High grade

fever

Rectal 36.1-37.8oC 38-38.9oC 39oC

Axillary 35-37.4oC 37.5-38.4oC 38.5oC

Etiologic classification

Most common cause infections of the upper respiratory tract.

A.     Respiratory infections 1.      Common cold 2.      Sinusitis 3.      Pharyngitis: most frequent cause of

fever in childhood. 4.      Otitis media, mastoiditis 5.      Pneumonia 6.      Pulmonary tuberculosis

Etiologic classification

B.     Urinary tract infections C.     Exanthemes In the prodromal phase of exanthmatous

diseases. D.     Enteric infections 1.      Salmonellosis 2.      Campylobacter enteritis 3.      Ascariasis 4.      Amebiazis

Etiologic classification

E.    Infections of the central neural system

1.      Meningitis 2.      Encephalitis 3.      Poliomyelitis F.    Infections of the liver and biliary tract 1.      Infectious hepatitis 2.      Cholangitis 3.      Liver abscess 4.  Granulamatous hepatitis due to

sarcoidosis,tuberculosis,hystoplasmosis, brucellosis.

Etiologic classification

G.     Infectıons involving the heart 1.      Rheumatic fever 2.      Infective endocarditis 3.      Myocarditis H.     Systemic infections 1.      Bacteremia 2.      Infective endocarditis 3.      Infectiosus mononucleosus 4. Epidemic influenza

Etiologic classification

5.      Enterovirus infections 6.      Cytomegalovirus infection 7.      Psittacosis 8.      Epidemic myalgia 9.      Malaria 10.    Toxoplazmosis 11.   Tuberculosis in nonpulmonary form 12.     Brucellosis 13. Others

Etiologic classification

I.     Abscesses, localized infections 1.      Osteomyelitis 2.      Intracranıal abscess 3.      Lung abscess 4.      Retropharyngeal abscess 5.      Alveolar abscess 6.      Perinephritic abscess 7.      Appendiceal abscess 8.      Pelvic abscess

Etiologic classification

9.      Mediastinitis 10.    Liver abscess 11.    Subpherenic abscess 12.   Spinal epidural infection 13.   Purulant pericarditis 14.   Empyema 15.    Immunodeficiency diseases 16.    Thrombophlebitis

Etiologic classification

II. Collagen-vascular or connective tissue disease

A.     Rheumatic fever B.     Serum sickness C.     Dermatomyositis D.     Periarteritis nodosa E.      Polyarteritis nodosa F.      Lupus erythematosus G.     Juvenile romatoid artritis H. Mixed connective tissue disease

Etiologic classification

III. Neoplastic diseases A.     Leukemia B.     Hodkin’s disease C.     Ewing tumor D.   Neuroblastoma with bone metastasis IV. Dehydration A.     Especially in newborn and young

infants B.     Hypertonic dehydration C.     Diabetes insipitus

Etiologic classification

V. Drugs, immunization A.   Disappears after 72 hours (after the

drug is stopped) B.     Immunuzation reactions VI. Blood diseases A.    Hemolytic anemia, especially during

a crisis B.     Transfusion reactions

Etiologic classification

VII. Hemorrhage A.   If bleeding occurs into a viscus or

other body tissue in hemorhagic disorders

B. Intracranial hemorrhage in the newborn

C.     Adrenal hemorrhage in the newborn D.     Hemorrhage into a tumor

Etiologic classification

VIII. Miscallenous causes A.     Kawasaki disease B.     Familial mediterranean fever C.     Takayasu’ arteritis D.     Virilizing adrenal hyperplasia E.      Inflammatory bowel disease (Crohn

disease) F.      Others

Treatment

Other than providing symptomatic relief, antipyretic therapy does not alter the course of common infectious diseases in normal children, and thus its use is controversial in these patients.

Antipyretic therapy is beneficial in high-risk patients Chronic cardiopulmonary diseases Metabolic disorders Neurologic diseases Febrile seizures

Treatment

Acetaminophen Aspirin Nonsteroidal anti-inflammatory

agents (e.g., ibuprofen) Aspirin - Reye syndrome High dose acetaminophen - renal injury

and hepatic failure Ibuprofen - dyspepsi, gatrointestinal

bleeding, reduced renal blood flow, and rarely aseptic meningitis, hepatic toxicity, or aplastic anemia

Bathing in warm water (not alcohol)

Hyperthermia

High body temperature not caused by hypothalamic thermoregulatory mechanisms

Increased heat production Vigorous exercise Malignant hyperthermia Neuroleptic malignant syndrome Hyperthyroidism

Decreased heat loss Wrapping in multiple blanket layers Atropine intoxication Prolonged exposure to high

environmental temperatures(heat stroke)

Malignant hyperthermia

Autosomal dominant disorder A history of drug exposure Previously affected family members Exposure the high environmental

temperatue Absence of the hypothalamic

regulated circadian rhythm It also occurs in patients with various

myopathic disorders.

Neuroleptic malignant syndrome Occurs following exposure to

phenothiazine-like agents and is indistinguishable from malignant hyperthermia.