fever İstanbul university cerrahpaşa medical faculty department of pediatrics prof. dr. ayşe...
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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.