Pneumonia

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Pneumonia is defined as "inflammation of the lungs."^[1]

Classification[edit]

Pneumonia can be classified along various dimensions including clinical setting, underlying etiology, and its gross appearance (bronchopneumonia versus lobar pneumonia).

Aspiration pneumonia[edit]

Community acquired pneumonia[edit]

The most common cause, streptococcus pneumonia, causes about a third of episodes.^[2]

Atypical pneumonia[edit]

Nosocomial pneumonia[edit]

Ventilator associated pneumonia[edit]

Diagnosis[edit]

Community acquired pneumonia[edit]

History and physical examination[edit]

A clinical prediction rule found the five following signs from the medical history and physical examination best predicted infiltrates on the chest radiograph of 1134 patients presenting to an emergency room:^[3]

• Temperature > 100 degrees F (37.8 degrees C)
• Pulse > 100 beats/min
• Crackles
• Decreased breath sounds
• Absence of asthma

• 5 findings - 84% to 91% probability
• 4 findings - 58% to 85%
• 3 findings - 35% to 51%
• 2 findings - 14% to 24%
• 1 findings - 5% to 9%
• 0 findings - 2% to 3%

A subsequent study^[5] comparing four clinical prediction rules to physician judgment found that two clinical prediction rules, the one above^[3] and another^[6] were more accurate than physician judgment because of the increased specificity of the prediction rules.

Blood tests[edit]

Some, but not all^[7] experts recommend prompt blood cultures.

Procalcitonin levels may help prognosticate.

Diagnostic imaging[edit]

Ultrasonography can diagnose community acquired pneumonia in one study with accuracy of:^[8]

• Sensitivity 93%
• Specificity 98%

Nosocomial pneumonia[edit]

Bronchoalveolar lavage with quantitative culture of the bronchoalveolar-lavage fluid or endotracheal aspiration with nonquantitative culture of the aspirate can help diagnose ventilator-associated pneumonia.^[10]

Treatment[edit]

Clinical practice guidelines are available.^[11]

Antibiotics[edit]

Some, but not all^[7] experts recommend prompt antibiotics.

Corticosteroids[edit]

In a randomized controlled trial of adults with community-acquired pneumonia, the relative risk ratio of prednisone 50 mg daily for 7 days, as compared to placebo, reduced the time to median time to clinical stability from 4.4 to to 1.3 days. ^[12]

In another randomized controlled trial of adults with community-acquired pneumonia, dexamethasone can reduce length of hospital stay. ^[13]

One trial reported increase in late-failures.^[14]

Aspiration pneumonia[edit]

Community acquired pneumonia[edit]

The 'respiratory quinolones' (levofloxacin, moxifloxacin, gemifloxacin) may be the best choices^[15] although the evidence is not clear^[16] and some studies show macrolides may be better^[17].

The optimal duration of antibiotic treatment for community acquired pneumonia is not clear.^[18]

Ventilator associated pneumonia[edit]

Treatments that are ineffective[edit]

Chest physiotherapy includes postural drainage, percussion, and vibration and has been call the 'ketchup-bottle method'^[19] of treating pneumonia. Chest physiotherapy and intermittent positive-pressure breathing have been shown not to help in a small randomized controlled trial.^[20] A subsequent systematic review did not find benefit.^[21]

Prognosis[edit]

Short term prognosis and the decision to hospitalize[edit]

The prognosis of community acquired pneumonia can be estimated with several clinical prediction rules of similar accuracy:^[22][23]

• Pneumonia severity index (PSI) - the PSI may^[24] or may not^[23] be more accurate than the CURB-65 and is available online (Pneumonia Severity Index Calculator).
  • Patients with PSI Risk groups I-III can usually be treated as an outpatient.^[25]
• CURB-65
• SMART-COP is a new clinical prediction rule that may be better according to a single study.^[26] Patients are high risk if they have three or more points from the following:
  • systolic blood pressure < 90 (2 points)
  • multilobar chest radiography involvement (1 point)
  • albumin level < 3.5 mg/dl (1 point)
  • high respiratory rate. 25 or more breaths per minute if less than 50 years old, else 30 or more breaths per minute (1 point)
  • tachycardia of 125 or more bpm (1 point)
  • confusion, new onset (1 point)
  • poor oxygenation. Either of the following adds 2 points:
    • PaO₂ < 70 mm Hg if less than 50 years old, else < 60 mm Hg
    • PaO₂/FiO₂ < 333 if less than 50 years old, else if less than 250.
  • arterial pH < 7.35 (2 points)
• SCAP score is a new clinical prediction rule that may be better than the Pneumonia severity index and CURB-65^[27]
• PIRO is another clinical prediction rule specifically for severe pneumonia.^[28]

C-reactive protein and procalcitonin[edit]

Several studies have compared the c-reactive protein and procalcitonin in the prognosis of pneumonia.^{[29][30][31][32]} The procalcitonin may^{[33][32][30][31]} or may not^[29] be more accurate.

Prognosis at the time of discharge[edit]

Abnormal medical signs at discharge are associated with higher mortality with 30 days.^[34]

Long term prognosis[edit]

Prevention[edit]

For more information, see: Pneumococcal vaccine.

Clinical practice guidelines are available for administering vaccines for pneumonia at http://www.cdc.gov/vaccines/.

References[edit]