Best Dx/Best Rx: Influenza and Influenza = Pneumonia

From: Subject: Best Dx/Best Rx: Influenza and Influenza Pneumonia Date: Wed, 3 Jun 2009 21:42:13 -0700 MIME-Version: 1.0 Content-Type: multipart/related; type="text/html"; boundary="----=_NextPart_000_0214_01C9E494.27E91810" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 This is a multi-part message in MIME format. ------=_NextPart_000_0214_01C9E494.27E91810 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Content-Location: http://www.acpmedicine.com/acp/newrxdx/rxdx/dxrx0725.htm Best Dx/Best Rx: Influenza and Influenza = Pneumonia

Influ= enza and=20 Influenza Pneumonia

Acute= =20 Bronchitis

Influenza and=20 Influenza Pneumonia

Frederick G. Hayden, M.D., = F.A.C.P.
University of=20 Virginia School of Medicine
Michael = G. Ison,=20 M.D., M.S.
Northwestern University Feinberg School of=20 Medicine

Defin= ition/Key=20 Clinical Features
Diffe= rential=20 Diagnosis
Best = Tests
Best = Therapy
Best = References

Definition/Key Clinical=20 Features

Classic = Influenza=20

Abrupt onset of fever, chills, headache, = myalgia,=20 malaise, anorexia, sore throat, cough, rhinorrhea
Respiratory symptoms more apparent as systemic = symptoms=20 subside=20
- Protracted cough from viral = tracheobronchitis=20
- Airway hyperactivity and abnormal pulmonary = function=20 test results for weeks to months=20
- Severe exacerbation of chronic pulmonary = disease=20 (asthma, bronchitis)

Influenza=20 Pneumonia=20

Rapidly progressive dyspnea, severe cough, = cyanosis,=20 diffuse rales, wheezing, variable sputum production, sometimes = bloody=20
Ranges from mild to rapidly fatal
1=967 days after typical influenza = onset=20
High mortality

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Differential = Diagnosis

Classic = Influenza=20

Other acute viral and bacterial respiratory=20 diseases

Influenza = Pneumonia=20

Secondary bacterial pneumonia =

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Best=20 Tests

Rapid assays for influenza A and B=20
- Specificity good=20
- Sensitivity 50%=9690%, depending on age, = specimen type,=20 and illness duration
- Sensitivity 50%=9660% in adults =
Sputum Gram stain may show polymorphonuclear = neutrophils=20 but rarely bacteria in primary viral pneumonia=20
Chest x-ray: bilateral (diffuse interstitial)=20 infiltrates=20
Perihilar pulmonary edema or dense = opacification=20
CBC: variable WBC count (leukopenia and = lymphopenia to=20 leukocytosis with left shift); thrombocytopenia

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Best=20 Therapy

Uncomplicated=20 Influenza

Antiviral Drugs=20

Neuraminidase inhibitors=20
- Active against both A and B=20
- Effective for early treatment; reduce = symptoms and=20 functional disability by 1=963 days=20
- Reduce risk of lower respiratory tract = complications;=20 oseltamivir also reduces risk of otitis in children and = hospitalization in=20 adults=20
- Oseltamivir
  - Dosage: adults and teenagers, 75 mg b.i.d. = for 5=20 days; children ≥ 1 year, 30=9675 mg (based on body weight) = b.i.d. for 5=20 days
- Zanamivir=20
  - Dosage: in adults and children ≥ 7 = years, two puffs=20 b.i.d. for 5 days=20
  - Two doses should be taken on the first day = of=20 treatment, provided that at least 2 hr elapse between doses =
M2 inhibitors
- Activity against influenza A viruses only =
- Increasing antiviral resistance in = circulating=20 influenza strains makes these agents unreliable in absence of = susceptibility=20 data
- Currently not recommended for the routine = management=20 of influenza=20
- Consult current CDC recommendations before = using these=20 agents: http://www.cdc.gov/flu/professionals/treatment=20
- For susceptible influenza A strains=20
  - Effective for early treatment: reduce = fever and=20 symptoms by 1=962 days
- Amantadine=20
  - Dose: 100 mg b.i.d.; reduce dose for age = ≥ 65 years=20 or renal insufficiency (creatinine clearance < 50=9680 = ml/min)=20
- Rimantadine=20
  - Dose: 100 mg b.i.d. or 200 mg q.d.; reduce = dose for=20 severe hepatic dysfunction, age ≥ 65 years, or renal = insufficiency=20 (creatinine clearance < 10 ml/min) =

Influenza Pneumonia=20

Treatment primarily supportive
- Oxygen; ventilatory support sometimes = needed=20
- Antivirals often used
- Screen for bacterial superinfection=20

Prevention

Antiviral Drugs=20

Neuraminidase inhibitors=20
- Effective for influenza A and B = prophylaxis=20
- Effective as seasonal prophylaxis or for = prophylaxis=20 after an exposure=20
- For postexposure prophylaxis, start within = 48 hr after=20 exposure to influenza=20
- Oseltamivir=20
  - Dosage: adults and teenagers, 75 mg daily = for 7=9610=20 days; children ≥ 1 year, 30=9675 mg (based on body weight) = daily for 7=9610=20 days
- Zanamivir=20
  - Dosage: adults and children 5 years and = older, two=20 puffs once daily for 7=9610 days
M2 inhibitors=20
- Amantadine and rimantadine=20
- Previously 70%=9690% effective against = influenza A=20 strains=20
- Increasing resistance has made these agents=20 unreliable=20
- Currently not recommended for = prophylaxis=20
- Consult current CDC advice before using = these agents:=20 http://www.cdc.gov/flu/professionals/treatment =

Influenza Vaccines=20

IM and intranasal forms=20
- Both trivalent (2 A, 1 B); both use = egg-grown virus,=20 possible reactions in allergic patients=20
- Take several weeks to elicit immunity =
- Efficacy of IM vaccine 70%=9690% in young = and=20 middle-aged adults, lower in elderly; approved for patients 6 months = and=20 older, including high-risk groups
- Intranasal vaccine approved for previously = healthy=20 patients 5 to 49 years
- Intranasal vaccine is live-attenuated and = therefore=20 contraindicated in patients with known or suspected immune=20 deficiencies

Frederick G. Hayden, M.D., F.A.C.P., has = no=20 commercial relationships with manufacturers of products or providers of = services=20 discussed in this module. Michael G. Ison, M.D., M.S., is a consultant = for=20 Roche.=20

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Best References

Kaiser L, et al: Curr Clin Top Infect Dis 19:112, = 1999=20 [PMID 10472483]

Moscona A: N Engl J Med 353:1363, 2005 [PMID=20 16192481]

Pearson ML, et al: MMWR Recomm Rep 55:1, 2006 = [PMID=20 16498385]

Writing Committee of the World Health = Organization=20 Consultation on Human Influenza A/H5: N Engl J Med 353:1374, 2005 [PMID=20 16192482]

November=20 2006

Acute=20 Bronchitis

Frederick G. Hayden, M.D.
University of = Virginia=20 School of Medicine
Michael G. Ison, = M.D.=20
University of Virginia School of Medicine

Defin= ition/Key=20 Clinical Features
Diffe= rential=20 Diagnosis
Best = Tests
Best = Therapy
Best= =20 References

Definition/Key Clinical=20 Features

Troubling or prolonged (less than 3 wk) = cough=20
Nonproductive cough or cough with scant mucoid = sputum=20
Variable wheezing=20
Acute or subacute onset usually following = viral upper=20 respiratory illness
No fever, dyspnea, or chest pain =

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Differential = Diagnosis

Pneumonia=20
Infection=20
- Bacterial=20
- Mycoplasmal=20
- Chlamydial=20
- Pertussis
For prolonged cough, consider the = following=20
- Asthma
- Reflux=20
- Postnasal drainage =

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Best=20 Tests

History and physical exam are usually = sufficient for=20 diagnosis=20
Chest x-ray is normal or unchanged
- Best test to rule out pneumonia=20

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Best=20 Therapy

Antibiotics generally not indicated=20
Oseltamivir treatment of acute influenza = reduces=20 frequency of acute bronchitis=20
Cough suppressant with codeine or = dextromethorphan may=20 be helpful in protracted cough (use with caution in patients with = underlying=20 chronic obstructive disease)=20
Inhaled beta agonist bronchodilators (e.g., = albuterol)=20 may decrease duration of cough

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Best = References

Gonzales, et al: Ann Intern Med 133:981, = 2000

Kaiser, et al: Arch Intern Med 163:1667,=20 2003

Smucny, et al: Cochrane Database = Syst Rev=20 (4):CD000249, 2003

July=20 2004

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