Fever

FEVER

DEFINITION OF FEVER
Fever is an elevation of body temperature that exceeds the normal daily variation, in conjunction with an increase in hypothalamic set point

NORMAL BODY TEMPERATURE

Maximum normal oral temperature At 6 AM : 37.2 At 4 PM : 37.7


Temperature ClassificationHypothermia<35.0 °C Normal36.5–37.5 °C Fever>37.5–38.3 °C Hyperthermia>37.5–38.3 °C Hyperpyrexia>40.0–41.5 °C Note: The difference between fever and hyperthermia is the mechanism

PATHOGENESIS OF FEVER

Infection Tissue injury - infarction, trauma Malignancy Drugs Immune-mediated disorders Other inflammatory disorders Endocrine disorders Factitious of self-induced fever
CAUSES OF FEVER


without localizing signs or symptoms
Viral Rhinovirus, adenovirus, parainfluenza Enterovirus Influenza
Bacterial Staphylococcus aureus Salmonella thyphi, S. parathyphi Streptococci
Post animal exposure Coxiella burneti (Q fever) Leptospira interrogans Brucella species
Granulomatous infection Mycobacterium tuberculosis Histoplasma capsulatum
Infections presenting as fever


Viral Measles,Rubella Bacterial Brucellosis,Tuberculosis,Syphilis (regional) Pyogenic infection Sta. aureus, Stre. Tuberculosis Scrofula (tbc. Cervical adenitis) Inguinal lymphadenopathy Syphilis, herpes Plague Yersinia pestis

Infections with Fever and Lymphadenomegaly(generalized)

DISCOMFORT DUE TO FEVER

HYPERTHERMIA

Heat production exceeds heat loss, and the temperature exceeds the individuals set point. Heat stroke ,drugs

TREATMENT OF FEVER

Most fevers are associated with self-limited infections, most commonly of viral origin. Treatment of underlying cause


Treatment Strategies
Acetaminophen is generally a first-line antipyretic due to being well tolerated with minimal side effects. Pediatric dose: 10-15mg/kg q4-6h (2400mg/day); adult: 650mg q 4 h(4000mg) Can be hepatotoxic in high doses; can upset stomach

Clinical Pearls

Don’t give aspirin to children under 18 years (Reye’s Syndrome)Try water sponge bath; remove blankets and heavy clothing; keep room at comfortable temp

DRUG FEVER

PATHOGENEGIS Contamination of the drug with a pyrogen or microorganism Pharmacologic action of the drug itself Allergic (hypersensitivity) reaction to the drug

DRUG FEVER

Onset and duration: Onset: 1-3 weeks after the start of therapy Duration: remits 2-3 days after therapy is stoped

DRUG FEVER

Fever out of proportion to clinical picture Associated findings: Rigor (43%), Myalgia (25%), Rash (18%), Headache (18%), Leukocytosis (22%), Eosinophilia (22%), Serum sickness,Proteinuria Abnormal liver function test

APPROACH TO THE PATIENT WITH FEVER

ACUTE FEBRILE ILLNESS

APPROACH TO FEVER

Personal History: Age Occupation Place of origin,Travel History Habits Sexual Practices Injection Drug Abuse Excessive Alcohol Use Consumption of Unpasteurized Dairy Products


APPROACH TO FEVER
Underlying Diseases: Splenectomy Surgical Implantation of Prosthesis Immunodeficiency Chronic Diseases: Cirrhosis Chronic Heart Diseases Chronic Lung Diseases

APPROACH TO FEVER

Drug History: Antipyretics Immunosuppressants Antibiotics Family History: TB in the Family Recent Infection in the Family

APPROACH TO FEVER

Associated Symptoms: Shaking chills Ear pain,Ear drainage,Hearing loss Visual and Eye Symptoms Sore Throat Chest and Pulmonary Symptoms Abdominal Symptoms Back pain, Joint or Skeletal pain

APPROACH TO FEVER

Physical Examination: Vital Signs Neurological Exam. Skin Lesions,Mucous Membrane Eyes ENT Lymphadenopathy Lungs and Heart Abdominal Region (Hepatomegaly,Splenomegaly) Musculoskeletal

LABORATORY STUDY IN PATIENT WITH FEBRILE ILLNESS

Assess the extent and severity of the inflammatory response to infection Determine the site(s) and complications of organ involvement by the process Determine the etiology of the infectious disease

FUO

FEVER OF UNKNOWN ORIGIN



FUO
Classic FUO Nosocomial FUO Neutropenic FUO HIV-Associated FUO

Classic FUO

Definition: Fever of 38.3 C or higher on several occasions Fever of more than 3 weeks duration Diagnosis uncertain, despite appropriate investigations after at least 3 outpatient visits or at least 3 days in hospital

Nosocomial FUO

Definition: Fever of 38.3 or higher on several occasions Infection was not manifest or incubating on admission Failure to reach a diagnosis despite 3 days of appropriate investigation in hospitalized patient

Neutropenic FUO

Definition: Fever of 38.3 or higher on several occasions Neutrophil count is <500/mm3 or is expected to fall to that level in 1 to 2 days Failure to reach a diagnosis despite 3 days of appropriate investigation

HIV-Associated FUO

Definition: Fever of 38.3 or higher on several occasions Fever of more than 3 weeks for outpatients or more than 3 days for hospitalized patients with HIV infection Failure to reach a diagnosis despite 3days of appropriate investigation



Causes of classical FUO
Infections
22-58%
Neoplasms
up to 30%
Noninfectiouse inflammatory diseases
up to 25%
Miscellaneous causes
up to 25%
Undiagnosed
up to 30%

Infections commonly associated with FUO

Localized pyogenic infectionsIntravascular infectionsSystemic bacterial infections (Tuberculosis, Brucellosis,…)Fungal infectionsViral infectionsParasitic infections

Malignancies commonly associated with FUO

Hodgkin’s diseaseNon-hodgkin’s lymphomaLeukemiaRenal cell carcinomaHepatomaColon carcinomaAtrial myxoma

Noninfectious inflammatory diseases with FUO

Collagen vascular/ hypersensitivity diseasesLupusStill’s diseaseTemporal arteritis (Giant cell arteritis) Granulomatouse diseasesCrohn’s diseaseSarcoidosisIdiopathic granulomatouse disease


Miscellaneous causes of FUO
Drug fever Factitious fever FMF Recurrent pulmonary emboli Subacute thyroiditis

FACTITIOUS FEVER

Diagnosis should be considered in any FUO, especially in: Young women Persons with medical training If the patients clinically well Disparity between temperature and pulse Absence of the normal diurnal pattern

Causes of FUO lasting > 6 month

Undiagnosed
19%
Miscellaneous
13%
Factitious
9%
Granulomatouse hepatitis
8%
Neoplasm
7%
Infection
6%
No fever
27%

Approach to FUO

Determine whether the patient has a true FUO Workup of true FUO: Careful history Serial follow-up histories Careful physical examination Physical examination should be repeated

Laboratory examination:

CBC(diff) PBS ESR U/A S/E
Culture of blood, urine,…Skin testSerologyANA

Imaging:

CXR Ultrasonography Radiographic contrast study Radioneuclide scan CT or MRI

Invasive Procedures

Biopsies: Bone marrow Skin lesion Lymph node Liver Temporal artery