APPROACH TO FEBRILE PATIENT.ppt

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Approach To The Febrile Patient Dr. Awadh Al-Anazi

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FEVER Is an elevation of body temperature above the normal circadian range as the result of a change in the thermoregulatory center located in the anterior hypothalamus and pre-optic area

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ThermoregulationBody heat is generated by: a) basal metabolic activity b) muscle movement Lost by: Conduction Convection (which is increased by wind or fanning) Evaporation which is increased by sweating

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Body temperature is controlled in the hypothalamus, which is directly sensitive to changes in core temperature The normal 'set-point' of core temperature is tightly regulated within 37 ± 0.5°C, as required to preserve normal function of many enzymes and other metabolic processes.

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In a hot environment, Sweating is the main mechanism for increasing heat loss. This usually occurs when the ambient temperature rises above 32.5°C or during exercise

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Febrile ResponseThe initiation of fever begins when exogenous or endogenous stimuli are presented to specialized host cells, principally monocytes and macrophages ,they will stimulates the synthesis and release of various pyrogenic cytokines including: 1)interleukin-1, interleukin-6 2)TNF-α, and 3)IFN-γ.

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1) Exogenous : stimuli from out side the host Like : microorganism, their products, or toxins and it is called Endotoxin Endotoxin : lipopolysaccharide ( LPS) LPS: is found in the outer membrane of all gram negative organism Action : 1) through stimulation of monocytes and macrophages 2) direct on endothelial cell of the brain to produce fever

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2) Endogenous pyrogens: Polypeptides that are produced by the body ( by monocytes and macrophages ) in response to stimuli that is usually triggered by infection or inflammation stimuli

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Pyrogens: Substances that cause fever are called pyrogens What are these pyrogens: Cytokines: Definition: Cytokines are regulatory polypeptides that are produced by 1) monocytes / macrophages 2) lymphocytes 3) endothelial and epithelial cell and hepatocytes

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The most important ones are : Interleukin 1 and 1 - :The most pyrogenic Tumor necrosis factor  Interferon Interleukin 6 ……………The least pyrogenic cytokines>fever develop within 1h of injection

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Mechanism of Action Cytokine-receptor interactions in the pre-optic region of the anterior hypothalamus activate phospholipase A. This enzyme liberates plasma membrane arachidonic acid as substrate for the cyclo-oxygenase pathway. The resulting mediator, prostaglandin E2, then modifies the responsiveness of thermosensitive neurons in the thermoregulatory centre.

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Diurnal variation 6 am : 37.2 &4pm : 37.7 Rectal temperature>0.6oC oral temperature Fever: Morning : AM >37.2o C Evening : PM >37.7o C

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Presentation of FeverFeeling hot A feeling of heat does not necessarily imply fever Rigors. profound chills accompanied by chattering of the teeth and severe shivering and implies a rapid rise in body temperature. Can be produced by : 1) brucellosis and malaria 2) sepsis with abscess 3) lymphoma Excessive sweating. Night sweats are characteristic of tuberculosis, but sweating from any cause is usually worse at night.

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Presentation of FeverHeadache Fever from any cause may provoke headache. Severe headache and photophobia, may suggests meningitis Delirium Mental confusion during fever is well described and relatively more common in extreme of age. Muscle pain Myalgia is characteristic of Viral infections such as influenza Malaria and brucellosis

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Hyperthermia Is an elevation of core temperature without elevation of the hypothalamic set point. Cause: inadequate heat loss Examples: 1) Heat stroke 2) Drug induced such as tricyclic antidepressant 3) Malignant hyperthermia. associated with psychiatric drugs

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Fever: Beneficial/Dangerous?Elevation of body temperature increases chance for survival Temperatures appear to increase 1) The phagocytic and Bactericidal activity of neurtrophils, and 2) The cytotoxic effects of lymphocytes 3)Thus:the growth and virulence of several bacterial species are impaired at high temperature .

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Fever PatternsIntermittent fever Remittent fever Hectic fever Sustained fever Relapsing

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Intermittent fever: exaggeration of the normal circadian rhythm,& temp. falls daily to normal, when the variation is large it is called hectic Cause: a) Deep seated infection b) Malignancy c) Drug fever Quotidian fever: hectic fever that occur daily. Remittent fever: Temperature falls daily but not to normal. Causes: a) tuberculosis b) viral infection c) many bacterial infections

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Relapsing fever: febrile episodes are separated by intervals of normal temperature a) Malaria fever every 3days (tertian).plasm. falciparam. or every 4 days (quartan) ..plasm .vivax b) Borrelia ..Days of fever followed by days of no fever.

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Fever Pattern Pel-Ebstein fever : fever for 3 to 10 days followed by no fever for 3 to 10 days Causes : a) Hodgkin lymphoma b) Tuberculosis

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Fever PatternFever pattern cannot be considered diagnostic for a particular infection or disease and the typical pattern is not usually seen because of use of : 1) Antipyretics 2) Steroids 3) Antibiotics

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Temperature – pulse dissociation ( Relative bradicardia ) is seen in A) Typhoid fever B) Brucellosis C) leptospirosis D) factitious fever E) acute rheumatic fever with cardiac conduction abnormality F) Viral myocarditis G) Endocarditis with valve ring abscess affecting conduction .

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Fever Patterns..DegreeFever with extreme degree: gram-negative bacteremia, Legionnaires‘ disease, and bacteremic pyelonephritis Noninfectious cause of extreme pyrexia: heat stroke, intracerebral hemorrhage

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Physical ExaminationFever may sometimes be absent: Seriously ill newborns Elderly patients, Uremic patient, Significantly malnourished individuals, Receiving corticosteroids or Continuous treatment with anti-inflammatory or antipyretic agents

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Approach to the Febrile Patient The most important step is Meticulous detailed history

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Approach to Fever Rule out common infection REMEMBER: UNCOMMON MANIFESTATIONS OF COMMON DISEASES ARE COMMONER THAN COMMON MANIFESTATIONS OF UNCOMMON ONES Careful history: 1) chronology of symptoms Detailed complain of the patient with the symotoms arranged chronologically

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Last Updated: 8th March 2018

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