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Chapter 26. Pneumonia

Russell T. Attridge

  • Pneumonia: acute infection of pulmonary parenchyma
  • Route of entry: aspiration of oropharyngeal contents, inhalation of aerosolized particles, hematogenous spread from extrapulmonary site
  • Alteration in host defenses: ↓ alveolar macrophage function, ↓ mucociliary clearance

Table 26-1 Pneumonia Definitions (Am J Respir Crit Care Med 2005;171:338)
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Table 26-1 Pneumonia Definitions (Am J Respir Crit Care Med 2005;171:338)

Community-acquired pneumonia (CAP)

Community-dwelling outpatient, or inpatient if diagnosis w/in 48h of admission

Healthcare-associated pneumonia (HCAP)

Community-dwelling patient admitted w/recent healthcare contact, recent hospitalization (≥2d in previous 90d), residence in a nursing home or LTCF, home infusion therapy or wound care, or chronic dialysis

Hospital-acquired pneumonia (HAP)

≥48h after hospital admission

Ventilator-associated pneumonia (VAP)

48–72h after endotracheal intubation

Diagnosis & Evaluation

(JAMA 1997;278:1440)

  • Required: acute infiltrate on chest radiography
  • Signs & symptoms of acute infection (↑ temp, ↑ WBCs), respiratory complaints (productive cough, dyspnea, pleuritic chest pain), systemic complaints (fatigue, anorexia, myalgias); auscultatory findings (dullness to percussion, Δ in breath sounds, wheezes, crackles, egophony)

Microbiological Diagnosis

  • Blood cultures (preantibiotics) = low positive yield (5–14%)—obtain if severe CAP/ICU admission & selected hospitalized patients (cavitary infiltrates, leukopenia, active EtOH abuse, severe liver disease, asplenia, pleural effusion)
  • Gram stain & sputum culture: variable yield, influenced by quality; in intubated patients: collect endotracheal aspirate
  • Urinary antigen tests → S. pneumoniae: sensitivity 50–80%, specificity >90% (Arch Intern Med 2011;171:166); L. pneumophila serogroup 1: sensitivity 70–90%, specificity 99%

Table 26-2 Prognostic Scoring Systems in CAP
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Table 26-2 Prognostic Scoring Systems in CAP

PSI (N Engl J Med 1997;336:243)

PSI Interpretation

Age

Objective Findings

Score

Class

Death, %

Men

Women

NH resident

Comorbidities

Neoplastic

Liver

CHF

Cerebrovascular

Renal

+ # of y

+ # of y

–10

+10

+30

+20

+10

+10

+10

AMS

RR ≥30

SBP <90

T <95 or ≥104°F

HR ≥125

Arterial pH <7.35

BUN ≥30

Na <130

Glucose ≥250

Hct <30

PaO2 <60

Pleural effusion

+20

+20

+20

+15

+10

+30

+20

+20

+10

+10

+10

+10

n/a*

≤70

71–90

91–130

>130

I

II

III

IV

V

<0.5

<1

1–3

∼9

∼30

Class

I–II

II–III

IV–V

Point of Care

Assess for outpt

Assess for inpt

Assess for ICU

CURB-65 (Thorax 2003;58:377)

CURB-65 Interpretation

Confusion

+1

Score

0–1

2

≥3

Death, %

1.5

∼9

22

Point of Care

Assess for outpt

Assess for inpt

Assess for ICU

Uremia (BUN ≥20)

>

+1

Respiratory rate ≥30

+1

Blood pressure (<90/60)

+1

Age ≥65

+1

*Risk class I: age <50y without any PSI comorbidities, AMS, or qualifying HR, RR, SBP, or temp.

Table 26-3 Criteria for Severe CAP
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Table 26-3 Criteria for Severe CAP

Major Criteria

Minor Criteria

Invasive mechanical ventilation

Septic shock with need for vasopressors

Note...

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