fever ppt.pptx

definition of fever,approach to fever and hyperthermia

1. FEVER AND HYPERTHERMIA Dr.G.VENKATA RAMANA MBBS DNB FAMILY MEDICINE

2. DEFINITIONS FEVER E levation in core body temperature that exceeds the normal daily variation and occurs in conjunction with an increase in the hypothalamic set point CHILL Sensation of cold RIGOR Profound chill with piloerection (goose flesh) associated with teeth chattering and severe shivering Normal core body temperature in the range of 36.5–37.5°C (97.7–99.5°F ) An a.m. oral temperature of >37.2°C (>98.9°F) or a p.m. temperature of >37.7°C (>99.9°F) defines a fever However,in practice,a general threshold of Temp >37.8 °C (100 ° F) or 38°C(100.4 ° F) is often used Normal daily temperature variation is typically 0.5°C ( 0.9°F) The normal body temperature is more towards the evening because of increased BMR and increased skeletal muscle activity

3. HYPERPYREXIA Fever >41.5°C (>106.7°F) Causes: S evere infections CNS hemorrhages HYPOTHALAMIC FEVER E levated temperature caused by abnormal hypothalamic function However, the majority of patients with hypothalamic damage have hypothermia not hyperthermia HYPERTHERMIA Uncontrolled increase in body temperature that exceeds the body's ability to lose heat The setting of the hypothalamic thermoregulatory center is unchanged Newborns , elderly patients, patients with chronic liver or kidney failure, and patients taking glucocorticoids , fever may not be present despite infection.

4. DRUG FEVER Fever that coincides with administration of a drug and disappears after the discontinuation of the drug, when no other cause for the fever is evident after a careful history, physical examination, and laboratory investigation FACTITIOUS FEVER Usually encountered in hospitalised patients attempting to malinger The situation is usually suspected when: A series of high temperatures is recorded to form an atypical pattern of fl uctuationthere is excessively high temperature (41.1°C) and above A recorded high temperature is unaccompanied by warm skin, tachycardia and other signs of fever such as a fl ushed face and sweating There is an absence of diurnal variation The patient may have surreptitiously dipped the thermometer in warm water, placed it in contact with a heat source or heated the bulb by friction with bedclothes or even mucous membranes of the mouth

5. Body temperature is controlled by the hypothalamus Neurons in both the preoptic anterior hypothalamus and the posterior hypothalamus receive two kinds of signals: one from peripheral nerves that transmit information from warmth/cold receptors in the skin and the other from the temperature of the blood bathing the region These two types of signals are integrated by the thermoregulatory center of the hypothalamus to maintain normal temperature

6. Once the hypothalamic set point is raised, neurons in the vasomotor center are activated and vasoconstriction Commences in the hands and feet Shunting of blood away from the periphery to the internal organs essentially decreases heat loss from the skin, and the person feels cold (Heat conservation) For most this is sufficient to raise body temperature by 1–2°C Shivering , which increases heat production from the muscles, may begin at this time; however, shivering is not required if mechanisms of heat conservation raise blood temperature sufficiently (Heat production) Nonshivering heat production from the liver also contributes to increasing core temperature (Heat production) Behavioral adjustments (e.g., putting on more clothing or bedding ) help raise body temperature by decreasing heat loss

7. The processes of heat conservation (vasoconstriction) and heat production (shivering and increased nonshivering thermogenesis) continue until the temperature of the blood bathing the hypothalamic neurons matches the new “thermostat setting ” Once that point is reached, the hypothalamus maintains the temperature at the febrile level by the same mechanisms of heat balance that function in the afebrile state When the hypothalamic set point is again reset downward (in response to either a reduction in the concentration of pyrogens or the use of antipyretics), the processes of heat loss through vasodilation and sweating are initiated Loss of heat by sweating and vasodilation continues until the blood temperature at the hypothalamic level matches the lower setting Behavioral changes (e.g., removal of clothing) facilitate heat loss

8. FEVER WITH RELATIVE BRADYCARDIA Typhoid fever Meningitis Viral fever (Influenza) Brucellosis Leptospirosis Drug induced fever Factitious fever FEVER WITH EXANTHEMS Rash appearing on first day of fever— Chicken pox Rash appearing on fourth day of fever— Measles Rash appearing on seventh day of fever— Typhoid FEBRILE CONVULSIONS It occurs in infants and children less than 5 years old Convulsions are common at temperatures more than 40°C It may not be a sign of cerebral disease

9. FEVER WITH RIGORS: This occurs in: Malaria Kala azar Filariasis Urinary tract infection, pyelonephritis Cholangitis Septicemia Infective endocarditis Abscesses,any site Lobar pneumonia

10. FEVER WITH JAUNDICE Malaria Hepatitis Leptospirosis Viral fevers Hepatoma FEVER AND GENERALISED LYMPHADENOPATHY Leukemia Lymphoma HIV infection Disseminated tuberculosis Brucellosis Toxoplasmosis FEVER AND EPITROCHLEAR LYMPHNODES Milary TB Lymphoma HIV infection Syphilis Local infections

11. FEVER WITH HEPATOSPLENOMEGALY Malaria Typhoid Lymphoma Leukemia Brucellosis Disseminated TB Infective endocarditis Kala azar FEVER WITH ALTERED SENSORIUM Meningitis Encephalitis Meningism -Typhoid HIV Brain abscess Brucellosis Sepsis CNS neoplasms

12. FEVER AND NIGHT SWEATS TB Lymphoma Brucellosis Abscess Infective endocarditis Alcohol withdrawl syndrome FEVER WITH HIGH ESR TB Temporal arteritis Carcinoma Lymphomas Abscess Myeloproliferative disorder

13. TEMPERATURE MEASUREMENT

14. TEMPERATURE MEASUREMENT RECTAL TEMPERATURE TYMPANIC TEMPERATURE

15. TYPES OF THERMOMETER

16. Rectal temperatures are generally 0.4°C (0.7°F) higher than oral readings In women who menstruate, the a.m. temperature is generally lower during the 2 weeks before ovulation; it then rises by ~0.6°C (1°F) with ovulation and stays at that level until menses occur During the luteal phase , the amplitude of the circadian rhythm remains the same Body temperature can be elevated in the postprandial state

17. HISTORY Onset Duration Continuous/remittent/intermittent Any evening rise in temperature Associated with rash Chills/rigors Subsides on medication Associated symptoms cold/cough/headache/ bodypains /sweating/ throat pain/vomiting/pain abdomen/ loose stools/ burning micturition

18. LABORATORY TESTS CBC/Peripheral smear MP Urine routine Dengue NS1 antigen Dengue IGM/IGG antibody LFT Lactate Blood culture Urine culture Weil felix Scrub typhus IGM/IGG antibody Brucella agglutination Leptospira IGM/IGG antibody HIV Sputum CBNAAT/Culture

19. MANAGEMENT OF FEVER Treatment of the cause Tepid sponging Anti pyretic agents Oral aspirin and NSAIDs effectively reduce fever but can adversely affect platelets and the gastrointestinal tract . Therefore, acetaminophen is preferred as an antipyretic . In children, acetaminophen or oral ibuprofen must be used because aspirin increases the risk of Reye’s syndrome . If the patient cannot take oral antipyretics, parenteral preparations of NSAIDs and rectal suppositories of various antipyretics can be used In hyperpyrexia, the use of cooling blankets facilitates the reduction of temperature

20. Mechanism of antipyretic agents Inhibitors of cyclooxygenase The synthesis of PGE2 depends on the constitutively expressed enzyme cyclooxygenase The substrate for cyclooxygenase is arachidonic acid released from the cell membrane Glucocorticoids act at two levels First, similar to the cyclooxygenase inhibitors, glucocorticoids reduce PGE2 synthesis by inhibiting the activity of phospholipase A2, which is needed to release arachidonic acid from the cell membrane Second, glucocorticoids block the transcription of the mRNA for the pyrogenic cytokines

21. Causes of Hyperthermia Syndromes Heat Stroke   Exertional : Exercise in higher than normal heat and/or humidity Nonexertional : Anticholinergics , including antihistamines; antiparkinsonian drugs; diuretics; phenothiazines Drug-Induced Hyperthermia  Amphetamines, cocaine, phencyclidine (PCP), methylenedioxymethamphetamine (MDMA; "ecstasy"), lysergic acid diethylamide (LSD), salicylates, lithium, anticholinergics , sympathomimetics Neuroleptic Malignant Syndrome   Phenothiazines ; butyrophenones , including haloperidol and bromperidol ; fluoxetine; loxapine ; tricyclic dibenzodiazepines ; metoclopramide; domperidone ; thiothixene ; molindone ; withdrawal of dopaminergic agents Serotonin Syndrome   Selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants Malignant Hyperthermia   Inhalational anesthetics, succinylcholine Endocrinopathy Thyrotoxicosis , pheochromocytoma Central Nervous System Damage   Cerebral hemorrhage, status epilepticus , hypothalamic injury

22. Heat stroke Exertional heat stroke Typically occurs in individuals exercising at elevated ambient temperatures and/or humidity. In a dry environment and at maximal efficiency, sweating can dissipate 600 kcal/h, requiring the production of >1 L of sweat. Even in healthy individuals, dehydration or the use of common medications (e.g., over-the-counter antihistamines with anticholinergic side effects) may precipitate exertional heat stroke Nonexertional heat stroke T ypically occurs in either very young or elderly individuals, particularly during heat waves The elderly, the bedridden, persons taking anticholinergic or antiparkinsonian drugs or diuretics, and individuals confined to poorly ventilated and non-air-conditioned environments are most susceptible

23. The serotonin syndrome Seen with selective serotonin uptake inhibitors (SSRIs), MAOIs, and other serotonergic medications, has many features that overlap with those of the neuroleptic malignant syndrome (including hyperthermia) but may be distinguished by the presence of diarrhea, tremor, and myoclonus rather than lead-pipe rigidity Malignant hyperthermia Occurs in individuals with an inherited abnormality of skeletal-muscle sarcoplasmic reticulum that causes a rapid increase in intracellular calcium levels in response to halothane and other inhalational anesthetics or to succinylcholine Elevated temperature, increased muscle metabolism, muscle rigidity, rhabdomyolysis , acidosis, and cardiovascular instability develop within minutes This rare condition is often fatal

24. The neuroleptic malignant syndrome Occurs in the setting of the use of neuroleptic agents (antipsychotic phenothiazines , haloperidol, prochlorperazine , metoclopramide) or the withdrawal of dopaminergic drugs and is characterized by "lead-pipe" muscle rigidity, extrapyramidal side effects, autonomic dysregulation , and hyperthermia This disorder appears to be caused by the inhibition of central dopamine receptors in the hypothalamus, which results in increased heat generation and decreased heat dissipation

25. Treatment of hyperthermia Physical cooling with sponging, fans, cooling blankets, and even ice baths should be initiated immediately in conjunction with the administration of IV fluids and appropriate pharmacologic agents If sufficient cooling is not achieved by external means, internal cooling can be achieved by gastric or peritoneal lavage with iced saline In extreme circumstances, hemodialysis or even cardiopulmonary bypass with cooling of blood may be performed Malignant hyperthermia should be treated immediately with cessation of anesthesia and IV administration of dantrolene sodium Dose 1–2.5 mg/kg given intravenously every 6 h for at least 24–48 h until oral dantrolene can be administered, if needed

26. Dantrolene at similar doses is indicated in the neuroleptic malignant syndrome and in drug-induced hyperthermia and may even be useful in the hyperthermia of the serotonin syndrome and thyrotoxicosis. The neuroleptic malignant syndrome also may be treated with bromocriptine , levodopa, amantadine, or nifedipine or by induction of muscle paralysis with curare and pancuronium . Tricyclic antidepressant overdose may be treated with physostigmine