Fever

This slide contains detailed information about the types, pathogenesis and presentation of fever.

1. FEVER PRESENTED BY : ANSHUMAN BAG B.D.S 3 RD YEA R .

2. It is an elevation of body temperature above the normal circadian variation as a result of the change in the thermoregulatory centre, located in the hypothalamus. Maximal Normal Oral Temperature At 6.00 AM : 37⁰C (98.6⁰F) At 6.00 PM : 37.6⁰C (99.6⁰F) The normal body temperature is more towards the evening because of increased BMR and increased skeletal muscle activity. Rectal temperature is 0.6⁰C(1⁰F) higher than oral temperature. Oral temperature is 0.6⁰C(1⁰F) higher than temperature recorded in axilla. FEVER

3. Physiological Variation of Temperature Chill is a sensation of cold that occurs in most fevers . Rigor is a profound chill with piloerection associated with teeth chattering and severe shivering. Chills or rigors occur when the thermostat , situated in the hypothalamus, is suddenly reset to a higher temperature due to presence of pyrogens. The body temperature then tends to rise to the newly reset level in the thermostat by conserving heat in the body by cutaneous vasoconstriction and involuntary contraction of skeletal muscles, experienced as chills or rigors. Chills or rigors may be commonly seen with bacterial, rickettsial, protozoal, influenzal infections. With every 1⁰F rise of temperature, above 100 ⁰F, the pulse rate increases by 10, the respiratory rate by 4, and BMR by 7.

4. PATHOGENESIS OF FEVER

5. Fever with Relative Bradycardia Typhoid Fever Meningitis Viral fever(Influenza) Brucellosis Leptospirosis Drug induced fever. Fever with Exanthems Rash appear on the following day of fever: First Day - Chicken Pox Second Day - Scarlet Fever Third Day – Pox(Small Pox) Fourth Day - Measles

6. Fifth Day – Typhus Sixth Day – Dengue Seventh Day – Enteric Fever MNEMONICS: Very – V aricella(Chicken Pox) Sick – S carlet Fever Person – Small P ox Must - M easles Take - T yph us Double - D engue Eggs – E nteric Fever

7. Febrile Convulsions It occurs in infants and children less than 5 years old. Convulsions are common at temperatures more than 40 ⁰C. It may not be a sign of cerebral disease. Normal 37⁰C to 37.6⁰C(98.6⁰F to 99.6⁰F) Febrile Above 37.8 ⁰C Hyperpyrexia >41⁰C(> 106⁰F) Hypothermia < 35⁰C(<95⁰F)

8. Continuous Fever The temperature remains elevated above the normal without touching the baseline and the fluctuation does not exceed 0.6⁰C, e.g. lobar pneumonia, infective endocarditis , enteric fever. Remittent Fever The temperature fluctuation exceeds 0.6⁰C, but without touching the baseline. Intermittent Fever The elevated temperature touches the baseline in between. In hectic or septic type of intermittent fever, the diurnal variation is extremely large, as occurs in septicaemia. Quotidian fever is a hectic fever occurring daily. Patterns of Fever

9. Relapsing Fever Febrile episodes are separated by normal temperature for more than one day, e.g. Borrelia infection, rat bite fever.

10. Drug Fever It is prolonged fever and may belong to any febrile pattern. There is relative bradycardia and hypotension. Pruritis, skin rash and arthralgia may occur. It begins 1 to 3 weeks after the start of the drugs and persists 2 to 3 days after the drug is withdrawn. Eosinophilia may be present. Important commonly used drugs producing fever are Sulphonamide, Penicillins, Iodides, Anti-TB Drugs, Anticonvulsants ,etc. Digoxin does not cause drug fever.

11. Hyperpyrexia It is an elevation of body core temperature, above 41⁰C(106⁰F),due to inadequate dissipation of heat. It is a medical emergency, since they are prone for sudden cardio respiratory arrest. Causes of Hyperpyrexia: Pontine hemorrhage Rheumatic Fever Meningococcal meningitis Septicaemia Cerebral malaria It is treated with parenteral anti- pyretics to set the elevated thermostat set point to a lower level. Chlorpromazine is sometimes helpful in reducing the body temperature.

12. Causes of Hyperthermia without Elevated Resetting of Thermostat Hyperthermia is characterised by an unchanged setting of the thermoregulatory centre with an uncontrolled increase in body temperature that exceeds body’s ability to lose heat. The causes are: Heat Stroke Malignant Hyperthermia Neuroleptic Malignant Syndrome Drug induced: Amphetamines, MAO inhibitors, Tricyclic antidepressants, Atropine Thyrotoxicosis Pheochromocytoma Hypothalamic Fever Serotonin Syndrome Central nervous system damage

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