Fever & ICU ID

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    Fever Background

    • Regulated by anterior hypothalamus (also brain stem, spinal cord, and sympathetic ganglia)
    • Temp is lower in AM and highest in PM
    • Mechanism:
      • Interleukin 1 (IL-1), TNF-a, IL-6, and IFN-gamma are released by monocytes and macrophages in response to inflammatory stimuli (or pathogens).
      • These inflammatory mediators stimulate circumventricular organs near the optic chiasm, activing phospholipase A2
        • Phospholipase A2 --> (activates) prostaglantin E2 --> (crosses BB barrier) --> ant. hypothalamus + brain stem. --> FEVER
    • Fever is beneficial because:
      • inhibits growth of viruses, bacteria, fungi, parasites.
      • Enhances activity of macrophages, neutrophils, and cell-mediated immune function.
    • Fever is harmful because:
      • Increases O2 demand:
        • Cardiac ischemia.
        • COPD exacerbation
        • Elderly with limited mental capacity get confusion.
        • Child seizures. (no proof that reducing the Temp prevents seizure).
    • Therefore:
      • Beneficial to lower body temp if heart disease, COPD, elderly, etc..
      • Use prostaglandin E2 synthesis inhibitors:
        • ASA
          • (avoid in children- Reye syndrome - hypoglycemic, fatty liver, encephalopathy, renal changes)
        • NSAIDs
          • Avoid in cardiac - coronary artery vasoconstriction.
        • Acetaminophen

    Fever of Unknown Origin

    • Definition:
    1. Must persist >3weeks.   (otherwise may be viral fever that's impossible to prove)
    2. Fever of >38.3°C on several occasions.   (bell curve distribution)
    3. No Diagnosis after 3 days of testing.
    • Differential:
      • Differential:

        • "The Big Three"
          • Infections
          • Neoplasms
          • Autoimmune Disese
        • "The Little Six"
          • Granulomatous Disease
          • Regional enteritis
          • Familiar Mediterraneal Fever (FMF)
          • Drug Fever
          • Pulmonary emboli
          • Factitions Fever

        Diagnostic Tests:

        • History/physical guides this!!!
          • Go where the money is!
        • CBC + diff
        • Blood smears - Giemsa and Wright stain
        • LFTs
        • ANA, Rheumatoid factor
        • ESR
        • Urinalysis
        • Blood, Urine Cultures
        • PPD skin test
        • Chest and Abdo CT.

         
      • "The Big 3"
        • Infections
          • Abscesses (abdo)
          • Osteomyelitis (bone scan)
          • Subacute bacterial endocarditis (blood culture - large volumes, TEE, murmur)
          • Biliary Infections
          • Subacute pyelonephritis
          • Miliary TB
          • Leptospirosis (animal or contaminated soil)
          • Viruses
            • EBV
            • CMV
        • Neoplasms
          • Lymphoma (Hodgkin)
          • Leukemia (aleukemic or preleukemic phase)
          • Hypernephroma (high sedimation rate)
          • Hepatoma
          • Atrial Myxoma
        • Autoimmune Disease
          • Do anti-nuclera and anti-DNA
          • Still's Disease
          • SLE
          • Hypersensitivity angiitis
          • Polymyalgia rheumatica + temporal arteritis
          • Polyarteritis nodosa
          • Mixed connective tissue disease
          • Sybacute thyroiditis
      • "The LIttle Six"
        • Granulomatous disease
        • Regional enteritis
        • Familial Mediterranean Fever (FMF)
        • Drug Fever
          • Antihistamines, barbiturates, dilantin, Hydralazine, Ibuprophen, Isoniazid, nitrofurantoin, penicillins, procainamide, quinidine, Salicylates, Thiouracil, mercaptopurine.
        • Pulmonary Emboli
        • Factitions Fever
          • Mess with mercury thermometers
          • Inject self with feces or saliva (health care worker hx, hiding cyringe)
    • Specific History
      • Review of systems
      • Past history of infections and family hx.
      • Epidemiology, animal exposure, insect bites, travel to developing countries or southwest  US or Ohio river valley.
      • Medications
    • Specific Exam
      • Skin for embolic lesions
      • Palpate all lymph nodes
      • Complete joint exam
      • Listen for cardic murmurs
      • Abdo exam (liver, spleen, masses/tenderness)

    FUO in HIV

    • Most common:
      • Mycobacterial infections:   (Mycobacterial blood culture)
        • Mycobacterium tuberculosis
        • M. avium intracellulare
        • Other atypical mycobacteria
      • Other bacterial infections
      • CMV   (CMV quantitative PCR)
      • Pneumocystis
      • Toxoplasmosis
      • Cryptococcus (Cryptococcal serum antigen)
      • Histoplasmosis (hard,  if disseminated - Bone marrow culture)

     

    Fever in ICU (Surgical and Medical)

    • Would infection must be excluded
      • Look for signs of infection
      • Immediate postop period:
        • Strep pyogenes --> septic shock and severe bacteremia.
      • Later post-op:
        • S. aureus + nosocomial pathogens (Pseudomonas, Klebsiella, and E.coli)
    • CULTURE + GRAM STAIN
    • Empiric Abx: cover G+'s and G-'s.
    • Specific cases:
      • Intra-abdominal abscess  
        • need CT
      • Intubated (Chest X ray and Blood Gasses)
        • Nasopharynx bacteria --> bronchitis/pneumonia
        • Sputum sample (>10 neutrophils/HPF and single organism on gram stain)
          • CXR and Blood gasses help diff btwn colonization and infection.
      • IV catheters (usually multiple
        • Line sepsis is common.
        • If new fever --> examine all IV and art lines for erythema, warmth, exudate.
        • If new fever + shock --> replace all lines, and maybe culture.
        • Usually: S. aureus, S. epidermidis
          • Use vancomycin (For resistant B-hemolytic strep) + 3rd gen cephalosporin (G-'s)
      • If lots of antibiotics
        • Worry of Candidemia (esp if 2+ site cultures grown Candida)
          • Cover with fluconazole or an echinocandin (caspofungin, anidulafungin, or micafungin) 
          • Blood culture
        • C.difficile colitis
      • Prolongued bladder catheterization
        • Nearly all patients with Foley's develop UTIs in 30days.
        • Urinalysis + Urine culture
      • NG Tubes.
        • Sinusitis + fever
        • Need sinus films + abx.
      • Non-infectious
        • Pulmonary embolus
        • Drug Fever (see above)
        • Undrained blood collections (let them resorb)
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