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Fever Of Unknown Origin
 

Fever Of Unknown Origin

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    Fever Of Unknown Origin Fever Of Unknown Origin Presentation Transcript

    • FEVER OF UNKNOWN ORIGIN Anupama Gowda Medical Student, 3 rd year Medical University of the Americas, Belize campus Internal Medicine Rotation Jackson Park Hospital
    • THE BASICS OF FEVER
      • PRESENTATION
      • Definition
      • Differentiation from hyperthermia
      • Mechanism
      • Measurement
      • Classifications
      • Importance of fever
      • Fever of Unknown Origin (FUO)
    • DEFINITION
      • Increase in body temperature to levels that are above normal
      • Normal = 37.0C or 98.6F
      • Temporary elevation in the body’s thermo-regulatory set point (usually 1-2 degrees)
      • Most frequent medical symptom
    • Differentiation from Hyperthermia
      • Increase in body temperature over the body’s thermoregulatory set point
      • Due to excessive heat production or insufficient thermoregulatory or both
    • OUTCOMES from HYPERTHERMIA
      • Previous “normal” body temperature now considered hypothermia
      • Effector mechanisms “kick” into action
      • Patient will experience the following: cold sensation, increased heart rate and muscle tone, and shivering (an attempt by the body to counteract the perceived hypothermia and in reaching the “new” thermoregulatory set point.
    • EFFECTOR MECHANISMS
      • Increased heat production causes increased muscle tone, shivering, hormones such as epinephrine and from thyroid to be released
      • Prevention of heat loss (e.g. vasoconstriction or crawling under the blanket)
      • Brown adipose tissue (mainly in babies)
      • Increased blood pressure (from the increased heart rate and vasoconstriction)
    • MECHANISM
      • Regulated by hypothalamus
      • Pyrogens induce fever—two types—endogenous and exogenous
      • (1) Exogenous—from outside sources of the body’s system (bacterial substance, LPS)
      • (2) Endogenous—from the body (IL-1)
    • MEASUREMENT
      • Instrument used: thermometer
      • Routes to measure: oral, axilla, rectal, and tympanic
      • Oral route is the most common route
      • Rectal is considered the most accurate and is one degree difference from the oral temperature
      • Axilla is 0.5 degrees difference from the oral temperature
    • Measurement
      • A person has fever if s/he has:
      • (1) Rectal >/= 38.0C or 100.4F
      • (2) Oral >/= 37.5C or 99.5F
      • (3) Axilla >/= 37.2C or 99.0F
    • Measurement
      • Fluctuations in body temperature can be due to:
      • (1) temperature changes throughout day
      • lowest at 4:00am, highest at 6:00pm
      • (2) individual differences
      • (3) women: various points in the menustrual cycles and used in
      • fertility planning
      • (4) fever can be increased after meals
      • (5) Psychological factors
      • (6) children have higher temperatures with
      • activity
      • (7) elderly have a decreased ability to generate body
      • heat during fever therefore a low-grade fever can be
      • serious
    • FOUR CLASSIFICATIONS
      • Low-grade: 38.0-39.0C (99.5-102.2F)
      • Moderate: 39.0-40.0C (102.2-104.0F)
      • High grade: >40.0C (>104.0F)
      • Hyperpyrexia: >42.0C (>107.6F)
    • IS FEVER GOOD OR BAD? Fever is GOOD….. and BAD…
    • Right Shift : increase in pCO2, temp, 2,3-BPG, altitude, exercise; decrease in pH Left Shift : decrease in pCO2, temp, 2,3-BPG, HbF; increase in pH Hemogloblin-oxygen dissociation curve
    • Oxygen-Dependent Myeloperoxidase System
    • SO WHEN IS FEVER “BAD”?
      • >/= 103.0F
      • Duration >/= one to three weeks
      • If this is only symptom….
    • FEVER OF UNKNOWN ORIGIN
      • Two Definitions:
      • Persdorf and Beeson (1961):
      • (1) Temperature >/= 38.3C (>101.0F) on
      • several occasions
      • (2) Duration > 3 weeks
      • (3) Failure to reach a diagnosis despite
      • one week of inpatient investigation
      • Duraek and Street modified the definition:
      • (1) Dividing into four categories (Classic, Nosocomial,
      • Neutropenic, HIV-Associated)
      • (2) Differentiating the categories by three features: patient’s
      • situation, duration of illness while under investigation, and the
      • cause
    • MAI (Mycobacterium avium/intercellulare), Tuberculosis, Non-Hodgkin’s, drug fever* Perianal infection, aspergillosis, candidemia, drug fever* Septic thrombophlebitis, sinusitis, C-diff, drug fever* Infections, malignancy, inflammatory diseases, drug fever* Causes (few examples) 3 days or 4 weeks as outpatient 3 days 3 days 3 days or 3 outpatient visits Duration of illness while under investigation Confirmed HIV + 1. Neutrophil count less than 500/ul OR 2. Expected to reach that in 1-2 days 1. Hospitalized 2. Acute care 3. No infection when admitted ALL others with fevers greater than/equal to three weeks Patient’s situation HIV-ASSOCIATED NEUTROPENIC NOSOCOMIAL CLASSIC FEATURE
    • DRUG FEVER
      • Cause common in all categories
      • Any febrile pattern which may be elevated by a drug
      • Can include any drug BUT pay attention to: anti-microbials (especially Beta lactams), cardiovascular (Quinidine), anti-neoplastic, and those that act on the central nervous system (phenytoin)
      • Other symptoms include:
      • (1) Bradycardia and hypotension (seen but not
      • common
      • (2) Eosinophilia and/or rash either:
      • --one to three weeks after the start of therapy
      • --two to three days after therapy has been stopped
    • Neutropenic
      • Most susceptible to bacterial and fungal infections (focal), bacteremic infections, infections involving catheters (sepsis and thrombophlebitis), and perianal infections
      • Most common: Candida and Aspergillus
      • Treatment:
      • (1) Vancomycin + Ceftazidime
      • (2) Cefepime
      • (3) Cabapenem with or without aminoglycoside
      • (4) Empirical coverage for bacterial sepsis
    • HIV-Associated
      • Caused by either HIV by itself or combined with one of the following:
      • (1) Mycobacterium avium/intracellulare
      • (2) TB
      • (3) Pneumocystis
      • (4) Salmonellosis
      • (5) Cryptococcosis
      • (6) Histoplasmosis
      • (7) Non-Hodgkin’s Lymphoma
      • (8) Drug Fever
      • Diagnosis:
      • (1) Mycobacterial infections—blood cultures, biopsies from liver,
      • bone marrow, and lymph nodes
      • (2) CT scan—identify large/mediastinal nodes
      • (3) Serological studies—identify the cryptococcal antigen
      • (4) Ga-67—pneumocysitis pulmonary infection
      • Treatment will be dependent on what is suspected.
    • NOSOCOMIAL
      • Two “KEY” Points to remember:
      • (1) Underlying susceptibility of the patient
      • (2) What are the potential complications
      • that this patient might concur during the
      • hospitalization? (Most Important)
      • Then the investigation begins….
    • NOSOCOMIAL-INVESTIGATION
      • Physical and/or lab exam:
      • (1) Focus—sites where the occult infections might be—original surgical or procedural field, abscesses, hematomas, or infected foreign bodies..
      • (2) Other sites—sinuses of intubated patients, prostatic abscesses in a man with a urinary catheter, suspicion of IV lines, septic phlebitis, and prostheses
      • Causes—variety—including:
      • (1) Clostridium difficile colitis especially associated with fever and leukocytosis before the onset of diarrhea
      • (2) Non-infectious—25% of cases—acalculous cholecystitis, DVT, pulmonary embolism
      • (3) Other causes include: drug fever, transfusion rxns, alcohol/drug withdrawal, adrenal insufficiency, thyroiditis, pancreatitis, gout, and pseudogout
      • Diagnosis made from:
      • (1) physical exams (Be Meticulous!)—repeat if necessary
      • (2) “focused” diagnostic techniques
      • (3) “speed up” the diagnostic tests
      • (4) multiple blood, wound, and fluid cultures
      • Treatment should be *SWIFT AND DECISIVE*
      • (1) Change IV lines and culture
      • (2) Stop the drugs for 72 hours
      • (3) Start empirical therapy ONLY IF you suspect bacteremia (e.g. Vancomycin for MRSA, broad- spectrum antibiotics for Gram (-) bacteria—pipercillin/tazobactam, ticarcillin, or clavulanate, imipenem, or meropenem)
    • CLASSIC
      • Does not “fit” into any of the three categories, then it’s “Classic”
      • Includes various causes BUT the leading cause is Infections especially extrapulmonary TB.
      • Second most common cause is neoplasms (decrease in malignancies due to the improvement of diagnostic technologies)
      • Diagnosis:
      • (1) Technologies have made it easy to detect such as CT Scan, MRI, radionuclide scanning, PET scans (increased detections of neoplasms and lymphomas)
      • (2) Broad-spectrum antibiotics have decreased the number of infections leading to FUO
      • (3) Highly specific and sensitive immunologic testing have decreased the number of undetected SLE and other autoimmune diseases
      • (4) There are certain diseases still difficult to diagnose…. WHY?
    • CLASSIC
      • Delayed antibody responses leading to mononucleosis syndromes (caused by EBV), CMV, or HIV
      • Urinary tract infections extending to kidney such as renal malacoplakia with submucosal plaques or nodules
      • Diagnoses such as intra-abdominal abscesses that are poorly localized, abscesses involving either the renal, retroperitoneal, and/or para-spinal areas
    • CLASSIC
      • Top Ten Leading Causes:
      • (1) lymphomas
      • (2) Collagen Vascular Disease
      • (3) Abscesses
      • (4) Undiagnosed cause
      • (5) Solid tumor
      • (6) Thrombosis or hematoma
      • (7) Granulomatous disease (non-mycobacterial)
      • (8) Endocarditis
      • (9) Mycobacterial disease
      • (10) Viral disease
      • (11) Any other remaining cause
    • CLASSIC
      • The three most common causes within the elderly include:
      • (1) Multisystem disease (most common or frequent—giant cell arteritis)
      • (2) TB (most common infection)
      • (3) Colon cancer (most important with a malignancy)
    • CLASSIC
      • Treatment is dependent on the cause
      • Harrison’s Principles of Internal Medicine, figure 18-5.
    • WHAT HAPPENS…?
      • If the duration of fever lasts for more than six months.. Infectious cause decreases, and the cause could be:
      • (1) Factitious disease—false deviation of temperature or self-induced disease
      • (2) Granulomatous hepatitis
      • (3) Neoplasm
      • (4) Still’s disease
      • (5) Collagen Vascular Disease
      • (6) Familiar Mediterranean Fever
      • (7) No fever
      • (8) Exaggerated circadian temperature rhythm without chills
      • (9) Increased pulse
      • (10) Nothing identified
      • (11) Other abnormalities
      • Treatment dependent on the cause.
    • SUMMARY
    • THANK YOU