fever-发热英语课件

1、Fever Zhou YunThe Affiliated Hospital of Medical College of Ningbo UniversityEmergency DepartmentObjective Definition Pathophysiology Pathogenesis Etiology and classification Clinical manifestationDefinition Definition of fever: A temperature above the normal range Normal body temperature 36-37 (set

2、 point) Circadian variation： Oral T 0. 5 Axillary TFeverPyrogens Elevated set-pointMaintaining an abnormally elevated TemperatureBMR(basal metabolic rate) increasesT = Elevated set-pointBMR 10% = T 0.6oC Hyperthermia Fever due to a disturbance of thermal regulatory controlExcessive heat production (

3、e.g. status epilepticus, hyperthyroidism)Decreased dissipation of heat (e.g. extensive skin disease) Loss of regulation(e.g. injury of the hypothalamic regulatory center)HyperthermiaExcessive heat productionT Decreased dissipationLoss of regulationPathophysiology Heat production Shivering Basal meta

4、bolic rate Heat is producted by tissues Absorbed from the environment Dermal vasoconstriction Heat loss The volume of blood flowing to skins surface Vaporization (sweating) Transfer the heat to the surrounding medium Dermal vasodilation Pathophysiology Regulated by the central nervous system The bod

5、y temperature is under control of the Preoptic area of the anterior hypothalamus370C390CHeat ProductionHeat LossHeat ProductionHeat LossShiveringMetabolic activityvasoconstrictionSweatingVasodilationSet -pointcoolingelevatingPathophysiology Hypothalamic thermostat Inherent Set Point: 37oC Lowest: 4

6、a.m; Peak: 810 p.m Fever follow this pattern Factors affect body temperature Exercise Menstrual cycle Environmental temperaturePathogenesis of feverWhat will make the hypothalamus change the set point?Pyrogens Substances that can cause fever Either exogenous or endogenous Exogenous Pyrogens From out

7、side the host Most of them are with high molecule weight Could not penetrate blood-brain barrier Stimulating monocytes and macrophages to induce the formation of endogenous pyrogenExogenous PyrogensMajority are microorganism, their products or toxinsGram-: Endotoxin (lipopolysaccaride ,LPS)Gram+: Li

8、poteichoic acidPeptidoglycanExotoxins and enterotoxinsExogenous PyrogensOthers Steroid hormone metabolites Antigen-antibody complex Endogenous Pyrogens In response to invasive stimuli: Exogenous pyrogen Chemical agents (amphotericin and other drug) Produced by cells of immune system of the host (mac

9、rophages, lymphocytes) Proteins designated monokines and lymphokines CytokinesEndogenous Pyrogens Cytokines IL (interleukin) TNF (tumor necrosis factors) IFN (interferon) Phagocytes and lymphocytes: major source of pyrogenic cytokines It may also released through autonomous production and secretionP

10、athogenesis of fever Bacteria provoke release of IL-1 Viral proteins stimulate IFN Combined production of several cytokines cause feverEtiology and classification Infective fever Non-infective feverInfective fever Metabolites from organism cause fever Most common causes of fever (50%60%) Bacteria py

11、rogens: Common cause of infective fever (43%) Viral pyrogens: (6%)Non-infective fever Absorption of necrotic substances Injury Ischemic necrosis Cell necrosis Allergy Antibiotics (penicillin-based) Endocrine and metabolic disturbances Hyperthyroidism DehydrationNon-infective fever Decreased eliminat

12、ion of heat from skinHeart failure Extensive dermatitis Antigen antibody reaction Rheumatic fever Serum disease Connective tissue diseaseNon-infective fever Dysfunction of central heat regulation Physical: heat stroke Chemical: barbiturate poisoning Mechanical: cerebral hemorrhage Dysfunction of veg

13、etative nervous system Sympathetic overactivity Clinical manifestation The grade of fever Low grade fever: 37.338 Middle grade fever: 3839 High grade fever: 39.141 Hyperthermia fever: 41Clinical manifestation Clinical course of fever Onset Sudden onset Pneumonia Gradual onset Typhoid Persistence Var

14、ies pattern Subsidence Crisis LysisCharacter of fever Continuous Fever T: kept at 3940 constantly Circadian variation: 39 Circadian variation 2 Rheumatic fever Tuberculosis Septicaemia Acute infectious endocarditisCharacter of fever Intermittent Fever T: sudden rising (few hours) and sudden decreasi

15、ng Malaria Acute pyelonephritis Character of fever Recurrent Fever T: abruptly rising to the peak, lasting for several days, suddenly decreasing to the normal Hodgkin disease Character of fever Undulant Fever T: Rising gradually to the peak (39) decreasing gradually to the normal, repeating for seve

16、ral times Brucellosis Character of fever Irregular Fever Tuberculosis Rheumatic fever BronchopneumoniaFever pattern as diagnostic clues Fever Pattern Cause Alternate-day fever Plasmodium vivax, P. Ovale fever every third day P. Malaria Relapsing fever daily for 36 days Borrelia sp fever-free interva

17、l rat bite fever for about 1 week Continuous “undulating” Brucellosis, typhoid Periodic pyrexia Hodgkins disease (Pel-Ebstein Phenomenon) with variable cyclesAssociated symptoms Chills or rigor Septicaemia Acute infections Congestion of conjunctiva Hemorrhage fever Herpes simplex Herpes virus (lobar

18、 pneumonia) Bleeding tendency In severe infection (hepatitis) Blood dyscrasia (leukemia)Associated symptoms LymphadenopathyLymphoma Cancer metastasis Enlargement of liver and spleenHepatitis RashDrug rash Measles Associated symptoms ArthralgiaGout Rheumatic disease ComaBarbiturate posioning Cerebral hemorrhageDiagnostic points Other symptoms Duration and magnitude Contacts with similar illness Occupational, travel, recreational exposure History of diseases Current medication AllergyFever of Unknown Origin (FUO) FUO defined by Petersdorf and Beeson (1961) Temperature 38.3 Repeatedly Duratio